Subject: RE: [PATCH v2] can: xilinx CAN controller support.

Hi Marc,

> -----Original Message-----
> From: Marc Kleine-Budde [mailto:[email protected]]
> Sent: Friday, February 14, 2014 12:51 AM
> To: Appana Durga Kedareswara Rao; [email protected]; Michal Simek;
> [email protected]; [email protected]; [email protected]
> Cc: [email protected]; [email protected]; linux-
> [email protected]; [email protected]; Appana Durga
> Kedareswara Rao
> Subject: Re: [PATCH v2] can: xilinx CAN controller support.
>
> On 02/12/2014 08:10 AM, Kedareswara rao Appana wrote:
> > This patch adds xilinx CAN controller support.
> > This driver supports both ZYNQ CANPS IP and Soft IP AXI CAN
> > controller.
> >
> > Signed-off-by: Kedareswara rao Appana <[email protected]>
> > ---
> > This patch is rebased on the 3.14 rc2 kernel.
> > Changes for v2:
> > - Updated with the review comments.
> > - Removed unnecessary debug prints.
> > - included tx,rx fifo depths in ZYNQ CANPS case also.
> > ---
> > .../devicetree/bindings/net/can/xilinx_can.txt | 45 +
> > drivers/net/can/Kconfig | 7 +
> > drivers/net/can/Makefile | 1 +
> > drivers/net/can/xilinx_can.c | 1153 ++++++++++++++++++++
> > 4 files changed, 1206 insertions(+), 0 deletions(-) create mode
> > 100644 Documentation/devicetree/bindings/net/can/xilinx_can.txt
> > create mode 100644 drivers/net/can/xilinx_can.c
> >
> > diff --git a/Documentation/devicetree/bindings/net/can/xilinx_can.txt
> > b/Documentation/devicetree/bindings/net/can/xilinx_can.txt
> > new file mode 100644
> > index 0000000..0e57103
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/can/xilinx_can.txt
> > @@ -0,0 +1,45 @@
> > +Xilinx Axi CAN/Zynq CANPS controller Device Tree Bindings
> > +---------------------------------------------------------
> > +
> > +Required properties:
> > +- compatible : Should be "xlnx,zynq-can-1.00.a" for Zynq
> CAN
> > + controllers and "xlnx,axi-can-1.00.a" for Axi CAN
> > + controllers.
> > +- reg : Physical base address and size of the Axi CAN/Zynq
> > + CANPS registers map.
> > +- interrupts : Property with a value describing the interrupt
> > + number.
> > +- interrupt-parent : Must be core interrupt controller
> > +- clock-names : List of input clock names - "ref_clk",
> "aper_clk"
> > + (See clock bindings for details. Two clocks are
> > + required for Zynq CAN. For Axi CAN
> > + case it is one(ref_clk)).
> > +- clocks : Clock phandles (see clock bindings for details).
> > +- tx-fifo-depth : Can Tx fifo depth.
> > +- rx-fifo-depth : Can Rx fifo depth.
> > +
> > +
> > +Example:
> > +
> > +For Zynq CANPS Dts file:
> > + zynq_can_0: zynq-can@e0008000 {
> > + compatible = "xlnx,zynq-can-1.00.a";
> > + clocks = <&clkc 19>, <&clkc 36>;
> > + clock-names = "ref_clk", "aper_clk";
> > + reg = <0xe0008000 0x1000>;
> > + interrupts = <0 28 4>;
> > + interrupt-parent = <&intc>;
> > + tx-fifo-depth = <0x40>;
> > + rx-fifo-depth = <0x40>;
> > + };
> > +For Axi CAN Dts file:
> > + axi_can_0: axi-can@40000000 {
> > + compatible = "xlnx,axi-can-1.00.a";
> > + clocks = <&clkc 0>;
> > + clock-names = "ref_clk" ;
> > + reg = <0x40000000 0x10000>;
> > + interrupt-parent = <&intc>;
> > + interrupts = <0 59 1>;
> > + tx-fifo-depth = <0x40>;
> > + rx-fifo-depth = <0x40>;
> > + };
> > diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig index
> > 9e7d95d..b180239 100644
> > --- a/drivers/net/can/Kconfig
> > +++ b/drivers/net/can/Kconfig
> > @@ -125,6 +125,13 @@ config CAN_GRCAN
> > endian syntheses of the cores would need some modifications on
> > the hardware level to work.
> >
> > +config CAN_XILINXCAN
> > + tristate "Xilinx CAN"
> > + depends on ARCH_ZYNQ || MICROBLAZE
> > + ---help---
> > + Xilinx CAN driver. This driver supports both soft AXI CAN IP and
> > + Zynq CANPS IP.
> > +
> > source "drivers/net/can/mscan/Kconfig"
> >
> > source "drivers/net/can/sja1000/Kconfig"
> > diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile index
> > c744039..0b8e11e 100644
> > --- a/drivers/net/can/Makefile
> > +++ b/drivers/net/can/Makefile
> > @@ -25,5 +25,6 @@ obj-$(CONFIG_CAN_JANZ_ICAN3) += janz-
> ican3.o
> > obj-$(CONFIG_CAN_FLEXCAN) += flexcan.o
> > obj-$(CONFIG_PCH_CAN) += pch_can.o
> > obj-$(CONFIG_CAN_GRCAN) += grcan.o
> > +obj-$(CONFIG_CAN_XILINXCAN) += xilinx_can.o
> >
> > ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG diff --git
> > a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c new file
> > mode 100644 index 0000000..642e6b4
> > --- /dev/null
> > +++ b/drivers/net/can/xilinx_can.c
> > @@ -0,0 +1,1153 @@
> > +/* Xilinx CAN device driver
> > + *
> > + * Copyright (C) 2012 - 2014 Xilinx, Inc.
> > + * Copyright (C) 2009 PetaLogix. All rights reserved.
> > + *
> > + * Description:
> > + * This driver is developed for Axi CAN IP and for Zynq CANPS Controller.
> > + * This program is free software: you can redistribute it and/or
> > +modify
> > + * it under the terms of the GNU General Public License as published
> > +by
> > + * the Free Software Foundation, either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/errno.h>
> > +#include <linux/init.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/netdevice.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/skbuff.h>
> > +#include <linux/string.h>
> > +#include <linux/types.h>
> > +#include <linux/can/dev.h>
> > +#include <linux/can/error.h>
> > +#include <linux/can/led.h>
> > +
> > +#define DRIVER_NAME "XILINX_CAN"
> > +
> > +/* CAN registers set */
> > +#define XCAN_SRR_OFFSET 0x00 /* Software reset */
> > +#define XCAN_MSR_OFFSET 0x04 /* Mode select */
> > +#define XCAN_BRPR_OFFSET 0x08 /* Baud rate prescaler */
> > +#define XCAN_BTR_OFFSET 0x0C /* Bit timing */
> > +#define XCAN_ECR_OFFSET 0x10 /* Error counter */
> > +#define XCAN_ESR_OFFSET 0x14 /* Error status */
> > +#define XCAN_SR_OFFSET 0x18 /* Status */
> > +#define XCAN_ISR_OFFSET 0x1C /* Interrupt status */
> > +#define XCAN_IER_OFFSET 0x20 /* Interrupt enable */
> > +#define XCAN_ICR_OFFSET 0x24 /* Interrupt clear */
> > +#define XCAN_TXFIFO_ID_OFFSET 0x30 /* TX FIFO ID */
> > +#define XCAN_TXFIFO_DLC_OFFSET 0x34 /* TX FIFO DLC */
> > +#define XCAN_TXFIFO_DW1_OFFSET 0x38 /* TX FIFO Data
> Word 1 */
> > +#define XCAN_TXFIFO_DW2_OFFSET 0x3C /* TX FIFO Data
> Word 2 */
> > +#define XCAN_RXFIFO_ID_OFFSET 0x50 /* RX FIFO ID */
> > +#define XCAN_RXFIFO_DLC_OFFSET 0x54 /* RX FIFO DLC */
> > +#define XCAN_RXFIFO_DW1_OFFSET 0x58 /* RX FIFO Data
> Word 1 */
> > +#define XCAN_RXFIFO_DW2_OFFSET 0x5C /* RX FIFO Data
> Word 2 */
>
> Can you define all register offsets via an enum please.
>

Ok

> > +/* CAN register bit masks - XCAN_<REG>_<BIT>_MASK */
> > +#define XCAN_SRR_CEN_MASK 0x00000002 /* CAN enable */
> > +#define XCAN_SRR_RESET_MASK 0x00000001 /* Soft Reset the
> CAN core */
> > +#define XCAN_MSR_LBACK_MASK 0x00000002 /* Loop back
> mode select */
> > +#define XCAN_MSR_SLEEP_MASK 0x00000001 /* Sleep mode
> select */
> > +#define XCAN_BRPR_BRP_MASK 0x000000FF /* Baud rate
> prescaler */
> > +#define XCAN_BTR_SJW_MASK 0x00000180 /* Synchronous
> jump width */
> > +#define XCAN_BTR_TS2_MASK 0x00000070 /* Time segment
> 2 */
> > +#define XCAN_BTR_TS1_MASK 0x0000000F /* Time segment
> 1 */
> > +#define XCAN_ECR_REC_MASK 0x0000FF00 /* Receive error
> counter */
> > +#define XCAN_ECR_TEC_MASK 0x000000FF /* Transmit error
> counter */
> > +#define XCAN_ESR_ACKER_MASK 0x00000010 /* ACK error */
> > +#define XCAN_ESR_BERR_MASK 0x00000008 /* Bit error */
> > +#define XCAN_ESR_STER_MASK 0x00000004 /* Stuff error */
> > +#define XCAN_ESR_FMER_MASK 0x00000002 /* Form error */
> > +#define XCAN_ESR_CRCER_MASK 0x00000001 /* CRC error */
> > +#define XCAN_SR_TXFLL_MASK 0x00000400 /* TX FIFO is full
> */
> > +#define XCAN_SR_ESTAT_MASK 0x00000180 /* Error status */
> > +#define XCAN_SR_ERRWRN_MASK 0x00000040 /* Error warning
> */
> > +#define XCAN_SR_NORMAL_MASK 0x00000008 /* Normal mode
> */
> > +#define XCAN_SR_LBACK_MASK 0x00000002 /* Loop back
> mode */
> > +#define XCAN_SR_CONFIG_MASK 0x00000001 /* Configuration
> mode */
> > +#define XCAN_IXR_TXFEMP_MASK 0x00004000 /* TX FIFO Empty
> */
> > +#define XCAN_IXR_WKUP_MASK 0x00000800 /* Wake up
> interrupt */
> > +#define XCAN_IXR_SLP_MASK 0x00000400 /* Sleep
> interrupt */
> > +#define XCAN_IXR_BSOFF_MASK 0x00000200 /* Bus off
> interrupt */
> > +#define XCAN_IXR_ERROR_MASK 0x00000100 /* Error interrupt
> */
> > +#define XCAN_IXR_RXNEMP_MASK 0x00000080 /* RX FIFO
> NotEmpty intr */
> > +#define XCAN_IXR_RXOFLW_MASK 0x00000040 /* RX FIFO
> Overflow intr */
> > +#define XCAN_IXR_RXOK_MASK 0x00000010 /* Message
> received intr */
> > +#define XCAN_IXR_TXOK_MASK 0x00000002 /* TX successful
> intr */
> > +#define XCAN_IXR_ARBLST_MASK 0x00000001 /* Arbitration
> lost intr */
> > +#define XCAN_IDR_ID1_MASK 0xFFE00000 /* Standard msg
> identifier */
> > +#define XCAN_IDR_SRR_MASK 0x00100000 /* Substitute
> remote TXreq */
> > +#define XCAN_IDR_IDE_MASK 0x00080000 /* Identifier
> extension */
> > +#define XCAN_IDR_ID2_MASK 0x0007FFFE /* Extended
> message ident */
> > +#define XCAN_IDR_RTR_MASK 0x00000001 /* Remote TX
> request */
> > +#define XCAN_DLCR_DLC_MASK 0xF0000000 /* Data length
> code */
> > +

Need to use BIT() Macro for the Masks?

> > +#define XCAN_INTR_ALL (XCAN_IXR_TXOK_MASK |
> XCAN_IXR_BSOFF_MASK |\
> > + XCAN_IXR_WKUP_MASK |
> XCAN_IXR_SLP_MASK | \
> > + XCAN_IXR_RXNEMP_MASK |
> XCAN_IXR_ERROR_MASK | \
> > + XCAN_IXR_ARBLST_MASK |
> XCAN_IXR_RXOK_MASK)
> > +
> > +/* CAN register bit shift - XCAN_<REG>_<BIT>_SHIFT */
> > +#define XCAN_BTR_SJW_SHIFT 7 /* Synchronous jump width
> */
> > +#define XCAN_BTR_TS2_SHIFT 4 /* Time segment 2 */
> > +#define XCAN_IDR_ID1_SHIFT 21 /* Standard Messg
> Identifier */
> > +#define XCAN_IDR_ID2_SHIFT 1 /* Extended Message
> Identifier */
> > +#define XCAN_DLCR_DLC_SHIFT 28 /* Data length code */
> > +#define XCAN_ESR_REC_SHIFT 8 /* Rx Error Count */
> > +
> > +/* CAN frame length constants */
> > +#define XCAN_ECHO_SKB_MAX 64
> > +#define XCAN_FRAME_MAX_DATA_LEN 8
> > +#define XCAN_TIMEOUT (50 * HZ)
>
> This is 50 seconds, is this intentional?
>

Sorry will make it as 1*HZ.

> > +
> > +/**
> > + * struct xcan_priv - This definition define CAN driver instance
> > + * @can: CAN private data structure.
> > + * @open_time: For holding timeout values
>
> Please remove open_time completely from the driver.

Ok

>
> > + * @waiting_ech_skb_index: Pointer for skb
> > + * @ech_skb_next: This tell the next packet in the queue
> > + * @waiting_ech_skb_num: Gives the number of packets waiting
> > + * @xcan_echo_skb_max_tx: Maximum number packets the driver
> can send
> > + * @xcan_echo_skb_max_rx: Maximum number packets the driver
> can receive
> > + * @napi: NAPI structure
> > + * @ech_skb_lock: For spinlock purpose
> > + * @read_reg: For reading data from CAN registers
> > + * @write_reg: For writing data to CAN registers
> > + * @dev: Network device data structure
> > + * @reg_base: Ioremapped address to registers
> > + * @irq_flags: For request_irq()
> > + * @aperclk: Pointer to struct clk
> > + * @devclk: Pointer to struct clk
> > + */
> > +struct xcan_priv {
> > + struct can_priv can;
> > + int open_time;
> > + int waiting_ech_skb_index;
> > + int ech_skb_next;
>
> please make them:
>
> unsigned int tx_head;
> unsigned int tx_tail;
>
> I'll explain how to use them later. Have a look at the ti_hecc driver.

Ok
>
> > + int waiting_ech_skb_num;
> > + int xcan_echo_skb_max_tx;
> > + int xcan_echo_skb_max_rx;
> > + struct napi_struct napi;
> > + spinlock_t ech_skb_lock;
> > + u32 (*read_reg)(const struct xcan_priv *priv, int reg);
> > + void (*write_reg)(const struct xcan_priv *priv, int reg, u32 val);
>
> Please remove read_reg, write_reg, as long as there isn't any BE support in
> the driver, call them directly.
>

As per yours and Michal discussion I am keeping this here (endianess of the IP is not fixed at compile time).

> > + struct net_device *dev;
> > + void __iomem *reg_base;
> > + unsigned long irq_flags;
> > + struct clk *aperclk;
> > + struct clk *devclk;
> > +};
> > +
> > +/* CAN Bittiming constants as per Xilinx CAN specs */ static const
> > +struct can_bittiming_const xcan_bittiming_const = {
> > + .name = DRIVER_NAME,
> > + .tseg1_min = 1,
> > + .tseg1_max = 16,
> > + .tseg2_min = 1,
> > + .tseg2_max = 8,
> > + .sjw_max = 4,
> > + .brp_min = 1,
> > + .brp_max = 256,
> > + .brp_inc = 1,
> > +};
> > +
> > +/**
> > + * xcan_write_reg - Write a value to the device register
> > + * @priv: Driver private data structure
> > + * @reg: Register offset
> > + * @val: Value to write at the Register offset
> > + *
> > + * Write data to the paricular CAN register */ static void
> > +xcan_write_reg(const struct xcan_priv *priv, int reg, u32 val)
>
> Please use the enum for instead of an int for the reg.

Ok
>
> > +{
> > + writel(val, priv->reg_base + reg);
> > +}
> > +
> > +/**
> > + * xcan_read_reg - Read a value from the device register
> > + * @priv: Driver private data structure
> > + * @reg: Register offset
> > + *
> > + * Read data from the particular CAN register
> > + * Return: value read from the CAN register */ static u32
> > +xcan_read_reg(const struct xcan_priv *priv, int reg) {
>
> same here

Ok
>
> > + return readl(priv->reg_base + reg);
> > +}
> > +
> > +/**
> > + * set_reset_mode - Resets the CAN device mode
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This is the driver reset mode routine.The driver
> > + * enters into configuration mode.
> > + *
> > + * Return: 0 on success and failure value on error */ static int
> > +set_reset_mode(struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + unsigned long timeout;
> > +
> > + priv->can.state = CAN_STATE_STOPPED;
> > +
> > + timeout = jiffies + XCAN_TIMEOUT;
> > + while (!(priv->read_reg(priv, XCAN_SR_OFFSET) &
> XCAN_SR_CONFIG_MASK)) {
> > + if (time_after(jiffies, timeout)) {
> > + netdev_warn(ndev, "timedout waiting for config
> mode\n");
> > + return -ETIMEDOUT;
> > + }
> > + usleep_range(500, 10000);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_set_bittiming - CAN set bit timing routine
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This is the driver set bittiming routine.
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_set_bittiming(struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + struct can_bittiming *bt = &priv->can.bittiming;
> > + u32 btr0, btr1;
> > + u32 is_config_mode;
> > +
> > + /* Check whether Xilinx CAN is in configuration mode.
> > + * It cannot set bit timing if Xilinx CAN is not in configuration mode.
> > + */
> > + is_config_mode = priv->read_reg(priv, XCAN_SR_OFFSET) &
> > + XCAN_SR_CONFIG_MASK;
> > + if (!is_config_mode) {
> > + netdev_alert(ndev,
> > + "Cannot set bittiming can is not in config mode\n");
> > + return -EPERM;
> > + }
> > +
> > + /* Setting Baud Rate prescalar value in BRPR Register */
> > + btr0 = (bt->brp - 1) & XCAN_BRPR_BRP_MASK;
> > +
> > + /* Setting Time Segment 1 in BTR Register */
> > + btr1 = (bt->prop_seg + bt->phase_seg1 - 1) & XCAN_BTR_TS1_MASK;
> > +
> > + /* Setting Time Segment 2 in BTR Register */
> > + btr1 |= ((bt->phase_seg2 - 1) << XCAN_BTR_TS2_SHIFT) &
> > + XCAN_BTR_TS2_MASK;
> > +
> > + /* Setting Synchronous jump width in BTR Register */
> > + btr1 |= ((bt->sjw - 1) << XCAN_BTR_SJW_SHIFT) &
> XCAN_BTR_SJW_MASK;
>
> All the masking should not be needed, as the bit timing is calculated within
> the bounds you specified.

Ok
>
> > + priv->write_reg(priv, XCAN_BRPR_OFFSET, btr0);
> > + priv->write_reg(priv, XCAN_BTR_OFFSET, btr1);
> > +
> > + netdev_dbg(ndev, "BRPR=0x%08x, BTR=0x%08x\n",
> > + priv->read_reg(priv, XCAN_BRPR_OFFSET),
> > + priv->read_reg(priv, XCAN_BTR_OFFSET));
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_start - This the drivers start routine
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This is the drivers start routine.
> > + * Based on the State of the CAN device it puts
> > + * the CAN device into a proper mode.
> > + *
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_start(struct net_device *ndev)
>
> Please name the function xcan_chip_start(), to for a common naming like
> the flexcan and at91 driver.
>

OK

> > +{
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + u32 err;
> > + unsigned long timeout;
> > +
> > + /* Check if it is in reset mode */
> > + if (priv->can.state != CAN_STATE_STOPPED)
>
> Don't depend on any state here, I suggest to do a softreset (or
> equivalent) of you CAN core and configure everything.
>

Ok
> > + err = set_reset_mode(ndev);
> > + if (err < 0)
> > + return err;
> > +
> > + /* Enable interrupts */
> > + priv->write_reg(priv, XCAN_IER_OFFSET, XCAN_INTR_ALL);
> > +
> > + /* Check whether it is loopback mode or normal mode */
> > + if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
> > + /* Put device into loopback mode */
> > + priv->write_reg(priv, XCAN_MSR_OFFSET,
> XCAN_MSR_LBACK_MASK);
> > + else
> > + /* The device is in normal mode */
> > + priv->write_reg(priv, XCAN_MSR_OFFSET, 0);
> > +
> > + if (priv->can.state == CAN_STATE_STOPPED) {
> > + /* Enable Xilinx CAN */
> > + priv->write_reg(priv, XCAN_SRR_OFFSET,
> XCAN_SRR_CEN_MASK);
> > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > + timeout = jiffies + XCAN_TIMEOUT;
> > + if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
> > + while ((priv->read_reg(priv, XCAN_SR_OFFSET)
> > + & XCAN_SR_LBACK_MASK) == 0) {
> > + if (time_after(jiffies, timeout)) {
> > + netdev_warn(ndev,
> > + "timedout for loopback
> mode\n");
> > + return -ETIMEDOUT;
> > + }
> > + usleep_range(500, 10000);
> > + }
> > + } else {
> > + while ((priv->read_reg(priv, XCAN_SR_OFFSET)
> > + & XCAN_SR_NORMAL_MASK) == 0) {
> > + if (time_after(jiffies, timeout)) {
> > + netdev_warn(ndev,
> > + "timedout for normal
> mode\n");
> > + return -ETIMEDOUT;
> > + }
> > + usleep_range(500, 10000);
> > + }
> > + }
> > + netdev_dbg(ndev, "status:#x%08x\n",
> > + priv->read_reg(priv, XCAN_SR_OFFSET));
> > + }
> > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_do_set_mode - This sets the mode of the driver
> > + * @ndev: Pointer to net_device structure
> > + * @mode: Tells the mode of the driver
> > + *
> > + * This check the drivers state and calls the
> > + * the corresponding modes to set.
> > + *
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_do_set_mode(struct net_device *ndev, enum can_mode mode) {
> > + int ret;
> > +
> > + switch (mode) {
> > + case CAN_MODE_START:
> > + ret = xcan_start(ndev);
> > + if (ret < 0)
> > + netdev_err(ndev, "xcan_start failed!\n");
> > + netif_wake_queue(ndev);
> > + break;
> > + default:
> > + ret = -EOPNOTSUPP;
> > + break;
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +/**
> > + * xcan_start_xmit - Starts the transmission
> > + * @skb: sk_buff pointer that contains data to be Txed
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This function is invoked from upper layers to initiate
> > +transmission. This
> > + * function uses the next available free txbuff and populates their
> > +fields to
> > + * start the transmission.
> > + *
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_start_xmit(struct sk_buff *skb, struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + struct net_device_stats *stats = &ndev->stats;
> > + struct can_frame *cf = (struct can_frame *)skb->data;
> > + u32 id, dlc, data[2] = {0, 0}, rtr = 0;
>
> I think you can drop the rtr varibale and use cf->can_id & CAN_RTR_FLAG
> instead.
>

OK
> > + unsigned long flags;
> > +
> > + if (can_dropped_invalid_skb(ndev, skb))
> > + return NETDEV_TX_OK;
> > +
> > + /* Watch carefully on the bit sequence */
> > + if (cf->can_id & CAN_EFF_FLAG) {
> > + /* Extended CAN ID format */
> > + id = ((cf->can_id & CAN_EFF_MASK) << XCAN_IDR_ID2_SHIFT)
> &
> > + XCAN_IDR_ID2_MASK;
> > + id |= (((cf->can_id & CAN_EFF_MASK) >>
> > + (CAN_EFF_ID_BITS-CAN_SFF_ID_BITS)) <<
> > + XCAN_IDR_ID1_SHIFT) & XCAN_IDR_ID1_MASK;
> > +
> > + /* The substibute remote TX request bit should be "1"
> > + * for extended frames as in the Xilinx CAN datasheet
> > + */
> > + id |= XCAN_IDR_IDE_MASK | XCAN_IDR_SRR_MASK;
> > +
> > + if (cf->can_id & CAN_RTR_FLAG) {
> > + /* Extended frames remote TX request */
> > + id |= XCAN_IDR_RTR_MASK;
> > + rtr = 1;
> > + }
> > + } else {
> > + /* Standard CAN ID format */
> > + id = ((cf->can_id & CAN_SFF_MASK) << XCAN_IDR_ID1_SHIFT)
> &
> > + XCAN_IDR_ID1_MASK;
> > +
> > + if (cf->can_id & CAN_RTR_FLAG) {
> > + /* Extended frames remote TX request */
> > + id |= XCAN_IDR_SRR_MASK;
> > + rtr = 1;
> > + }
> > + }
> > +
> > + dlc = (cf->can_dlc & 0xf) << XCAN_DLCR_DLC_SHIFT;
>
> No need to mask dlc, it's valid.
>
OK

> > +
> > + if (dlc > 0)
>
> You've copied my speudo code :)
> But you have to use (cf->can_dlc > 0) here, as dlc is the shifted value.

Yes :) I missed it will change

>
> > + data[0] = be32_to_cpup((__be32 *)(cf->data + 0));
> > + if (dlc > 4)
> > + data[1] = be32_to_cpup((__be32 *)(cf->data + 4));
> > +
> > + can_put_echo_skb(skb, ndev, priv->ech_skb_next);
>
> can_put_echo_skb(skb, ndev,
> priv->tx_head % priv->xcan_echo_skb_max_tx);
>
> priv->tx_head++;
>

Ok
> > +
> > + /* Write the Frame to Xilinx CAN TX FIFO */
> > + priv->write_reg(priv, XCAN_TXFIFO_ID_OFFSET, id);
> > + priv->write_reg(priv, XCAN_TXFIFO_DLC_OFFSET, dlc);
> > + if (!rtr) {
> > + priv->write_reg(priv, XCAN_TXFIFO_DW1_OFFSET, data[0]);
> > + priv->write_reg(priv, XCAN_TXFIFO_DW2_OFFSET, data[1]);
> > + stats->tx_bytes += cf->can_dlc;
>
> Please add a comment which write triggers the tx. What in case of the rtr?
> Which write triggers the tx then?
>

Ok Will Add

In RTR Case the below write triggers the trasmission
priv->write_reg(priv, XCAN_TXFIFO_DLC_OFFSET, dlc);
In Normal case this write
priv->write_reg(priv, XCAN_TXFIFO_DW2_OFFSET, data[1]);
Triggers the transmission.

In Btw: Due to the limitations in the IP( Tx DLC register is a write only Register)
I can't put this stats->tx_bytes += cf->can_dlc; in the tx interrupt routine.

> > + }
> > +
> > + priv->ech_skb_next = (priv->ech_skb_next + 1) %
> > + priv->xcan_echo_skb_max_tx;
>
> Please remove, it's not needed.
>
Ok

> > +
> > + spin_lock_irqsave(&priv->ech_skb_lock, flags);
> > + priv->waiting_ech_skb_num++;
> > + spin_unlock_irqrestore(&priv->ech_skb_lock, flags);
>
> All 3 not needed.
>
Ok
> > +
> > + /* Check if the TX buffer is full */
> > + if (priv->read_reg(priv, XCAN_SR_OFFSET) & XCAN_SR_TXFLL_MASK)
> {
> > + netif_stop_queue(ndev);
> > + netdev_err(ndev, "TX register is still full!\n");
> > + return NETDEV_TX_BUSY;
>
> If this is true, there is a Bug in the flow control. It should be moved to the
> beginning of the function, see at91_can's xmit function.

Yes this Condition Becomes true.
Will put the below check in the Beginning of this function
>
> /* Check if the TX buffer is full */
> if (unlikely(priv->read_reg(priv, XCAN_SR_OFFSET) &
> XCAN_SR_TXFLL_MASK)) {
> netif_stop_queue(ndev);
> netdev_err(ndev,
> "BUG!, TX FIFO full when queue awake!\n");
> return NETDEV_TX_BUSY;
> }
>
> > + } else if (priv->waiting_ech_skb_num == priv-
> >xcan_echo_skb_max_tx) {
> > + netif_stop_queue(ndev);
> > + netdev_err(ndev, "waiting:0x%08x, max:0x%08x\n",
> > + priv->waiting_ech_skb_num, priv-
> >xcan_echo_skb_max_tx);
> > + return NETDEV_TX_BUSY;
> > + }
>
> This is a the regular flow control function and must be called before a TX
> complete interrupt can trigger. Your tx-complete interrupt is probably
> always enabled?
>

Yes. The tx-completed interrupt always enabled.

> So here you check the fill level of the FIFO:
>
> if ((priv->tx_head - priv->tx_tail) ==
> priv->xcan_echo_skb_max_tx)
> netif_stop_queue(ndev);
>
> If it's full, stop the queue. The you trigger the tx, the tx complete interrupt
> gets called and the queue will be restarted.
>

Ok
> > +
> > + return NETDEV_TX_OK;
> > +}
> > +
> > +/**
> > + * xcan_rx - Is called from CAN isr to complete the received
> > + * frame processing
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This function is invoked from the CAN isr(poll) to process the Rx
> > +frames. It
> > + * does minimal processing and invokes "netif_receive_skb" to
> > +complete further
> > + * processing.
> > + * Return: 0 on success and negative error value on error */ static
> > +int xcan_rx(struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + struct net_device_stats *stats = &ndev->stats;
> > + struct can_frame *cf;
> > + struct sk_buff *skb;
> > + u32 id_xcan, dlc, data[2] = {0, 0}, rtr = 0;
> > +
> > + skb = alloc_can_skb(ndev, &cf);
> > + if (!skb)
> > + return -ENOMEM;
> > +
> > + /* Read a frame from Xilinx zynq CANPS */
> > + id_xcan = priv->read_reg(priv, XCAN_RXFIFO_ID_OFFSET);
> > + dlc = priv->read_reg(priv, XCAN_RXFIFO_DLC_OFFSET) &
> > +XCAN_DLCR_DLC_MASK;
>
> Better do the shift to dlc.
>
Ok

> > +
> > + /* Change Xilinx CAN data length format to socketCAN data format
> */
> > + cf->can_dlc = get_can_dlc((dlc & XCAN_DLCR_DLC_MASK) >>
> > + XCAN_DLCR_DLC_SHIFT);
>
> Then it's just: get_can_dlc(dlc);

Ok
>
> > +
> > + /* Change Xilinx CAN ID format to socketCAN ID format */
> > + if (id_xcan & XCAN_IDR_IDE_MASK) {
> > + /* The received frame is an Extended format frame */
> > + cf->can_id = (id_xcan & XCAN_IDR_ID1_MASK) >> 3;
> > + cf->can_id |= (id_xcan & XCAN_IDR_ID2_MASK) >>
> > + XCAN_IDR_ID2_SHIFT;
> > + cf->can_id |= CAN_EFF_FLAG;
> > + if (id_xcan & XCAN_IDR_RTR_MASK) {
> > + cf->can_id |= CAN_RTR_FLAG;
> > + rtr = 1;
> > + }
> > + } else {
> > + /* The received frame is a standard format frame */
> > + cf->can_id = (id_xcan & XCAN_IDR_ID1_MASK) >>
> > + XCAN_IDR_ID1_SHIFT;
> > + if (id_xcan & XCAN_IDR_RTR_MASK) {
> > + cf->can_id |= CAN_RTR_FLAG;
> > + rtr = 1;
> > + }
> > + }
> > +
> > + if (!rtr) {
> > + data[0] = priv->read_reg(priv, XCAN_RXFIFO_DW1_OFFSET);
> > + data[1] = priv->read_reg(priv, XCAN_RXFIFO_DW2_OFFSET);
> > +
> > + /* Change Xilinx CAN data format to socketCAN data format
> */
> > + *(__be32 *)(cf->data) = cpu_to_be32(data[0]);
> > + if (cf->can_dlc > 4)
> > + *(__be32 *)(cf->data + 4) = cpu_to_be32(data[1]);
> > + }
> > + can_led_event(ndev, CAN_LED_EVENT_RX);
> > +
> > + netif_receive_skb(skb);
> > +
> > + stats->rx_bytes += cf->can_dlc;
> > + stats->rx_packets++;
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_err_interrupt - error frame Isr
> > + * @ndev: net_device pointer
> > + * @isr: interrupt status register value
> > + *
> > + * This is the CAN error interrupt and it will
> > + * check the the type of error and forward the error
> > + * frame to upper layers.
> > + */
> > +static void xcan_err_interrupt(struct net_device *ndev, u32 isr) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + struct net_device_stats *stats = &ndev->stats;
> > + struct can_frame *cf;
> > + struct sk_buff *skb;
> > + u32 err_status, status;
> > +
> > + skb = alloc_can_err_skb(ndev, &cf);
> > + if (!skb) {
> > + netdev_err(ndev, "alloc_can_err_skb() failed!\n");
> > + return;
> > + }
> > +
> > + err_status = priv->read_reg(priv, XCAN_ESR_OFFSET);
> > + priv->write_reg(priv, XCAN_ESR_OFFSET, err_status);
> > + status = priv->read_reg(priv, XCAN_SR_OFFSET);
> > +
> > + if (isr & XCAN_IXR_BSOFF_MASK) {
> > + priv->can.state = CAN_STATE_BUS_OFF;
> > + cf->can_id |= CAN_ERR_BUSOFF;
> > + priv->can.can_stats.bus_off++;
> > + /* Leave device in Config Mode in bus-off state */
> > + priv->write_reg(priv, XCAN_SRR_OFFSET,
> XCAN_SRR_RESET_MASK);
> > + can_bus_off(ndev);
> > + } else if ((status & XCAN_SR_ESTAT_MASK) ==
> XCAN_SR_ESTAT_MASK) {
> > + cf->can_id |= CAN_ERR_CRTL;
> > + priv->can.state = CAN_STATE_ERROR_PASSIVE;
> > + priv->can.can_stats.error_passive++;
> > + cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE |
> > + CAN_ERR_CRTL_TX_PASSIVE;
> > + } else if (status & XCAN_SR_ERRWRN_MASK) {
> > + cf->can_id |= CAN_ERR_CRTL;
> > + priv->can.state = CAN_STATE_ERROR_WARNING;
> > + priv->can.can_stats.error_warning++;
> > + cf->data[1] |= CAN_ERR_CRTL_RX_WARNING |
> > + CAN_ERR_CRTL_TX_WARNING;
> > + }
> > +
> > + /* Check for Arbitration lost interrupt */
> > + if (isr & XCAN_IXR_ARBLST_MASK) {
> > + cf->can_id |= CAN_ERR_LOSTARB;
> > + cf->data[0] = CAN_ERR_LOSTARB_UNSPEC;
> > + priv->can.can_stats.arbitration_lost++;
> > + }
> > +
> > + /* Check for RX FIFO Overflow interrupt */
> > + if (isr & XCAN_IXR_RXOFLW_MASK) {
> > + cf->can_id |= CAN_ERR_CRTL;
> > + cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
> > + stats->rx_over_errors++;
> > + stats->rx_errors++;
> > + priv->write_reg(priv, XCAN_SRR_OFFSET,
> XCAN_SRR_RESET_MASK);
> > + }
> > +
> > + /* Check for error interrupt */
> > + if (isr & XCAN_IXR_ERROR_MASK) {
> > + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> > + cf->data[2] |= CAN_ERR_PROT_UNSPEC;
> > +
> > + /* Check for Ack error interrupt */
> > + if (err_status & XCAN_ESR_ACKER_MASK) {
> > + cf->can_id |= CAN_ERR_ACK;
> > + cf->data[3] |= CAN_ERR_PROT_LOC_ACK;
> > + stats->tx_errors++;
> > + }
> > +
> > + /* Check for Bit error interrupt */
> > + if (err_status & XCAN_ESR_BERR_MASK) {
> > + cf->can_id |= CAN_ERR_PROT;
> > + cf->data[2] = CAN_ERR_PROT_BIT;
> > + stats->tx_errors++;
> > + }
> > +
> > + /* Check for Stuff error interrupt */
> > + if (err_status & XCAN_ESR_STER_MASK) {
> > + cf->can_id |= CAN_ERR_PROT;
> > + cf->data[2] = CAN_ERR_PROT_STUFF;
> > + stats->rx_errors++;
> > + }
> > +
> > + /* Check for Form error interrupt */
> > + if (err_status & XCAN_ESR_FMER_MASK) {
> > + cf->can_id |= CAN_ERR_PROT;
> > + cf->data[2] = CAN_ERR_PROT_FORM;
> > + stats->rx_errors++;
> > + }
> > +
> > + /* Check for CRC error interrupt */
> > + if (err_status & XCAN_ESR_CRCER_MASK) {
> > + cf->can_id |= CAN_ERR_PROT;
> > + cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ |
> > + CAN_ERR_PROT_LOC_CRC_DEL;
> > + stats->rx_errors++;
> > + }
> > + priv->can.can_stats.bus_error++;
> > + }
> > +
> > + netif_rx(skb);
> > + stats->rx_packets++;
> > + stats->rx_bytes += cf->can_dlc;
> > +
> > + netdev_dbg(ndev, "%s: error status register:0x%x\n",
> > + __func__, priv->read_reg(priv, XCAN_ESR_OFFSET));
> }
> > +
> > +/**
> > + * xcan_state_interrupt - It will check the state of the CAN device
> > + * @ndev: net_device pointer
> > + * @isr: interrupt status register value
> > + *
> > + * This will checks the state of the CAN device
> > + * and puts the device into appropriate state.
> > + */
> > +static void xcan_state_interrupt(struct net_device *ndev, u32 isr) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > +
> > + /* Check for Sleep interrupt if set put CAN device in sleep state */
> > + if (isr & XCAN_IXR_SLP_MASK)
> > + priv->can.state = CAN_STATE_SLEEPING;
> > +
> > + /* Check for Wake up interrupt if set put CAN device in Active state
> */
> > + if (isr & XCAN_IXR_WKUP_MASK)
> > + priv->can.state = CAN_STATE_ERROR_ACTIVE; }
> > +
> > +/**
> > + * xcan_rx_poll - Poll routine for rx packets (NAPI)
> > + * @napi: napi structure pointer
> > + * @quota: Max number of rx packets to be processed.
> > + *
> > + * This is the poll routine for rx part.
> > + * It will process the packets maximux quota value.
> > + *
> > + * Return: number of packets received */ static int
> > +xcan_rx_poll(struct napi_struct *napi, int quota) {
> > + struct net_device *ndev = napi->dev;
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + u32 isr, ier;
> > + int work_done = 0;
> > +
> > + isr = priv->read_reg(priv, XCAN_ISR_OFFSET);
> > + while ((isr & XCAN_IXR_RXNEMP_MASK) && (work_done < quota)) {
> > + if (isr & XCAN_IXR_RXOK_MASK) {
> > + priv->write_reg(priv, XCAN_ICR_OFFSET,
> > + XCAN_IXR_RXOK_MASK);
> > + if (xcan_rx(ndev) < 0)
> > + return work_done;
> > + work_done++;
> > + } else {
> > + priv->write_reg(priv, XCAN_ICR_OFFSET,
> > + XCAN_IXR_RXNEMP_MASK);
> > + break;
> > + }
>
> What does the XCAN_IXR_RXOK_MASK mean if it's send and undset?

XCAN_IXR_RXOK_MASK Means it is successfully received one packet

>
> > + priv->write_reg(priv, XCAN_ICR_OFFSET,
> XCAN_IXR_RXNEMP_MASK);
> > + isr = priv->read_reg(priv, XCAN_ISR_OFFSET);
> > + }
> > +
> > + if (work_done < quota) {
> > + napi_complete(napi);
> > + ier = priv->read_reg(priv, XCAN_IER_OFFSET);
> > + ier |= (XCAN_IXR_RXOK_MASK |
> XCAN_IXR_RXNEMP_MASK);
> > + priv->write_reg(priv, XCAN_IER_OFFSET, ier);
>
> Is this a read-modify-write register? I mean will an interrupt get disabled, if
> you write a 0-bit in the IER register? What does the ICR register?

ISR- Interrupt Status Register (Read only register)
IER- Interrupt Enable Register(R/w register)
ICR- Interrupt Clear Register.(write only register)

The Interrupt Status Register (ISR) contains bits that are set when a particular interrupt condition occurs. If
the corresponding mask bit in the Interrupt Enable Register is set, an interrupt is generated.
Interrupt bits in the ISR can be cleared by writing to the Interrupt Clear Register

>
> > + }
> > + return work_done;
> > +}
> > +
> > +/**
> > + * xcan_tx_interrupt - Tx Done Isr
> > + * @ndev: net_device pointer
> > + */
> > +static void xcan_tx_interrupt(struct net_device *ndev) {
> > + unsigned long flags;
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + struct net_device_stats *stats = &ndev->stats;
> > + u32 processed = 0, txpackets;
> > +
> > + stats->tx_packets++;
> > + netdev_dbg(ndev, "%s: waiting total:%d,current:%d\n", __func__,
> > + priv->waiting_ech_skb_num, priv-
> >waiting_ech_skb_index);
> > +
> > + txpackets = priv->waiting_ech_skb_num;
> > +
> > + if (txpackets) {
> > + can_get_echo_skb(ndev, priv->waiting_ech_skb_index);
> > + priv->waiting_ech_skb_index =
> > + (priv->waiting_ech_skb_index + 1) %
> > + priv->xcan_echo_skb_max_tx;
> > + processed++;
> > + txpackets--;
> > + }
> > +
> > + spin_lock_irqsave(&priv->ech_skb_lock, flags);
> > + priv->waiting_ech_skb_num -= processed;
> > + spin_unlock_irqrestore(&priv->ech_skb_lock, flags);
>
> This all simplyfies to a:
> can_get_echo_skb(ndev, priv->tx_tail %
> priv->xcan_echo_skb_max_tx);
> priv->tx_tail++;
>

Ok

> I think you should add some kind of loop here, it there is more than one tx-
> complete per IRQ.
>

Ok

> > +
> > + netdev_dbg(ndev, "%s: waiting total:%d,current:%d\n", __func__,
> > + priv->waiting_ech_skb_num, priv-
> >waiting_ech_skb_index);
> > +
> > + netif_wake_queue(ndev);
> > +
> > + can_led_event(ndev, CAN_LED_EVENT_TX); }
> > +
> > +/**
> > + * xcan_interrupt - CAN Isr
> > + * @irq: irq number
> > + * @dev_id: device id poniter
> > + *
> > + * This is the xilinx CAN Isr. It checks for the type of interrupt
> > + * and invokes the corresponding ISR.
> > + *
> > + * Return:
> > + * IRQ_NONE - If CAN device is in sleep mode, IRQ_HANDLED otherwise
> > +*/ static irqreturn_t xcan_interrupt(int irq, void *dev_id) {
> > + struct net_device *ndev = (struct net_device *)dev_id;
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + u32 isr, ier;
> > +
> > + /* Get the interrupt status from Xilinx CAN */
> > + isr = priv->read_reg(priv, XCAN_ISR_OFFSET);
> > + if (!isr)
> > + return IRQ_NONE;
> > +
> > + netdev_dbg(ndev, "%s: isr:#x%08x, err:#x%08x\n", __func__,
> > + isr, priv->read_reg(priv, XCAN_ESR_OFFSET));
> > +
> > + /* Check for the type of interrupt and Processing it */
> > + if (isr & (XCAN_IXR_SLP_MASK | XCAN_IXR_WKUP_MASK)) {
> > + priv->write_reg(priv, XCAN_ICR_OFFSET,
> (XCAN_IXR_SLP_MASK |
> > + XCAN_IXR_WKUP_MASK));
> > + xcan_state_interrupt(ndev, isr);
> > + }
> > +
> > + /* Check for Tx interrupt and Processing it */
> > + if (isr & XCAN_IXR_TXOK_MASK) {
> > + priv->write_reg(priv, XCAN_ICR_OFFSET,
> XCAN_IXR_TXOK_MASK);
> > + xcan_tx_interrupt(ndev);
> > + }
> > +
> > + /* Check for the type of error interrupt and Processing it */
> > + if (isr & (XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
> > + XCAN_IXR_BSOFF_MASK |
> XCAN_IXR_ARBLST_MASK)) {
> > + priv->write_reg(priv, XCAN_ICR_OFFSET,
> (XCAN_IXR_ERROR_MASK |
> > + XCAN_IXR_RXOFLW_MASK |
> XCAN_IXR_BSOFF_MASK |
> > + XCAN_IXR_ARBLST_MASK));
> > + xcan_err_interrupt(ndev, isr);
> > + }
> > +
> > + /* Check for the type of receive interrupt and Processing it */
> > + if (isr & (XCAN_IXR_RXNEMP_MASK | XCAN_IXR_RXOK_MASK)) {
> > + ier = priv->read_reg(priv, XCAN_IER_OFFSET);
> > + ier &= ~(XCAN_IXR_RXNEMP_MASK |
> XCAN_IXR_RXOK_MASK);
> > + priv->write_reg(priv, XCAN_IER_OFFSET, ier);
> > + napi_schedule(&priv->napi);
> > + }
> > + return IRQ_HANDLED;
> > +}
> > +
> > +/**
> > + * xcan_stop - Driver stop routine
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This is the drivers stop routine. It will disable the
> > + * interrupts and put the device into configuration mode.
> > + */
> > +static void xcan_stop(struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + u32 ier;
> > +
> > + /* Disable interrupts and leave the can in configuration mode */
> > + ier = priv->read_reg(priv, XCAN_IER_OFFSET);
> > + ier &= ~XCAN_INTR_ALL;
> > + priv->write_reg(priv, XCAN_IER_OFFSET, ier);
> > + priv->write_reg(priv, XCAN_SRR_OFFSET, XCAN_SRR_RESET_MASK);
> > + priv->can.state = CAN_STATE_STOPPED; }
> > +
> > +/**
> > + * xcan_open - Driver open routine
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * This is the driver open routine.
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_open(struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + int ret;
> > +
> > + ret = request_irq(ndev->irq, xcan_interrupt, priv->irq_flags,
> > + ndev->name, (void *)ndev);
> > + if (ret < 0) {
> > + netdev_err(ndev, "Irq allocation for CAN failed\n");
> > + return ret;
> > + }
> > +
> > + /* Set chip into reset mode */
> > + ret = set_reset_mode(ndev);
> > + if (ret < 0)
> > + netdev_err(ndev, "mode resetting failed failed!\n");
>
> Is this critical?

This condition usually won't fail.
But if the controller has a problems at the h/w level in that case putted this err print.
If you want me to change it as a warning will do

>
> > +
> > + /* Common open */
> > + ret = open_candev(ndev);
> > + if (ret)
> > + return ret;
>
> You should free the interrupt handler if this fails.

Ok
>
> > +
> > + ret = xcan_start(ndev);
> > + if (ret < 0)
> > + netdev_err(ndev, "xcan_start failed!\n");
> > +
> > +
> > + can_led_event(ndev, CAN_LED_EVENT_OPEN);
> > + napi_enable(&priv->napi);
> > + netif_start_queue(ndev);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_close - Driver close routine
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * Return: 0 always
> > + */
> > +static int xcan_close(struct net_device *ndev) {
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > +
> > + netif_stop_queue(ndev);
> > + napi_disable(&priv->napi);
> > + xcan_stop(ndev);
> > + free_irq(ndev->irq, ndev);
> > + close_candev(ndev);
> > +
> > + can_led_event(ndev, CAN_LED_EVENT_STOP);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_get_berr_counter - error counter routine
> > + * @ndev: Pointer to net_device structure
> > + * @bec: Pointer to can_berr_counter structure
> > + *
> > + * This is the driver error counter routine.
> > + * Return: 0 always
> > + */
> > +static int xcan_get_berr_counter(const struct net_device *ndev,
> > + struct can_berr_counter *bec)
> > +{
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > +
> > + bec->txerr = priv->read_reg(priv, XCAN_ECR_OFFSET) &
> XCAN_ECR_TEC_MASK;
> > + bec->rxerr = ((priv->read_reg(priv, XCAN_ECR_OFFSET) &
> > + XCAN_ECR_REC_MASK) >> XCAN_ESR_REC_SHIFT);
> > + return 0;
> > +}
> > +
> > +static const struct net_device_ops xcan_netdev_ops = {
> > + .ndo_open = xcan_open,
> > + .ndo_stop = xcan_close,
> > + .ndo_start_xmit = xcan_start_xmit,
> > +};
> > +
> > +#ifdef CONFIG_PM_SLEEP
> > +/**
> > + * xcan_suspend - Suspend method for the driver
> > + * @_dev: Address of the platform_device structure
> > + *
> > + * Put the driver into low power mode.
> > + * Return: 0 always
> > + */
> > +static int xcan_suspend(struct device *_dev) {
> > + struct platform_device *pdev = container_of(_dev,
> > + struct platform_device, dev);
> > + struct net_device *ndev = platform_get_drvdata(pdev);
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > +
> > + if (netif_running(ndev)) {
> > + netif_stop_queue(ndev);
> > + netif_device_detach(ndev);
> > + }
> > +
> > + priv->write_reg(priv, XCAN_MSR_OFFSET,
> XCAN_MSR_SLEEP_MASK);
> > + priv->can.state = CAN_STATE_SLEEPING;
> > +
> > + clk_disable(priv->aperclk);
> > + clk_disable(priv->devclk);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * xcan_resume - Resume from suspend
> > + * @dev: Address of the platformdevice structure
> > + *
> > + * Resume operation after suspend.
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_resume(struct device *dev) {
> > + struct platform_device *pdev = container_of(dev,
> > + struct platform_device, dev);
> > + struct net_device *ndev = platform_get_drvdata(pdev);
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > + int ret;
> > +
> > + ret = clk_enable(priv->aperclk);
> > + if (ret) {
> > + dev_err(dev, "Cannot enable clock.\n");
> > + return ret;
> > + }
> > + ret = clk_enable(priv->devclk);
> > + if (ret) {
> > + dev_err(dev, "Cannot enable clock.\n");
> > + return ret;
> > + }
> > +
> > + priv->write_reg(priv, XCAN_MSR_OFFSET, 0);
> > + priv->write_reg(priv, XCAN_SRR_OFFSET, XCAN_SRR_CEN_MASK);
> > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > +
> > + if (netif_running(ndev)) {
> > + netif_device_attach(ndev);
> > + netif_start_queue(ndev);
> > + }
> > +
> > + return 0;
> > +}
> > +#endif
> > +
> > +static SIMPLE_DEV_PM_OPS(xcan_dev_pm_ops, xcan_suspend,
> xcan_resume);
> > +
> > +/**
> > + * xcan_probe - Platform registration call
> > + * @pdev: Handle to the platform device structure
> > + *
> > + * This function does all the memory allocation and registration for
> > +the CAN
> > + * device.
> > + *
> > + * Return: 0 on success and failure value on error */ static int
> > +xcan_probe(struct platform_device *pdev) {
> > + struct resource *res; /* IO mem resources */
> > + struct net_device *ndev;
> > + struct xcan_priv *priv;
> > + int ret, fifodep;
> > +
> > + /* Create a CAN device instance */
> > + ndev = alloc_candev(sizeof(struct xcan_priv),
> XCAN_ECHO_SKB_MAX);
> > + if (!ndev)
> > + return -ENOMEM;
> > +
> > + priv = netdev_priv(ndev);
> > + priv->dev = ndev;
> > + priv->can.bittiming_const = &xcan_bittiming_const;
> > + priv->can.do_set_bittiming = xcan_set_bittiming;
> > + priv->can.do_set_mode = xcan_do_set_mode;
> > + priv->can.do_get_berr_counter = xcan_get_berr_counter;
> > + priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
> > + CAN_CTRLMODE_BERR_REPORTING;
> > +
> > + /* Get IRQ for the device */
> > + ndev->irq = platform_get_irq(pdev, 0);
> > +
> > + spin_lock_init(&priv->ech_skb_lock);
> > + ndev->flags |= IFF_ECHO; /* We support local echo */
> > +
> > + platform_set_drvdata(pdev, ndev);
> > + SET_NETDEV_DEV(ndev, &pdev->dev);
> > + ndev->netdev_ops = &xcan_netdev_ops;
> > +
> > + /* Get the virtual base address for the device */
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + priv->reg_base = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(priv->reg_base)) {
> > + ret = PTR_ERR(priv->reg_base);
> > + goto err_free;
> > + }
> > + ndev->mem_start = res->start;
> > + ndev->mem_end = res->end;
> > +
> > + priv->write_reg = xcan_write_reg;
> > + priv->read_reg = xcan_read_reg;
> > +
> > + ret = of_property_read_u32(pdev->dev.of_node, "tx-fifo-depth",
> > + &fifodep);
> > + if (ret < 0)
> > + goto err_free;
> > + priv->xcan_echo_skb_max_tx = fifodep;
> > +
> > + ret = of_property_read_u32(pdev->dev.of_node, "rx-fifo-depth",
> > + &fifodep);
> > + if (ret < 0)
> > + goto err_free;
> > + priv->xcan_echo_skb_max_rx = fifodep;
> > +
> > + /* Getting the CAN devclk info */
> > + priv->devclk = devm_clk_get(&pdev->dev, "ref_clk");
> > + if (IS_ERR(priv->devclk)) {
> > + dev_err(&pdev->dev, "Device clock not found.\n");
> > + ret = PTR_ERR(priv->devclk);
> > + goto err_free;
> > + }
> > +
> > + /* Check for type of CAN device */
> > + if (of_device_is_compatible(pdev->dev.of_node,
> > + "xlnx,zynq-can-1.00.a")) {
> > + priv->aperclk = devm_clk_get(&pdev->dev, "aper_clk");
> > + if (IS_ERR(priv->aperclk)) {
> > + dev_err(&pdev->dev, "aper clock not found\n");
> > + ret = PTR_ERR(priv->aperclk);
> > + goto err_free;
> > + }
> > + } else {
> > + priv->aperclk = priv->devclk;
> > + }
> > +
> > + ret = clk_prepare_enable(priv->devclk);
> > + if (ret) {
> > + dev_err(&pdev->dev, "unable to enable device clock\n");
> > + goto err_free;
> > + }
> > +
> > + ret = clk_prepare_enable(priv->aperclk);
> > + if (ret) {
> > + dev_err(&pdev->dev, "unable to enable aper clock\n");
> > + goto err_unprepar_disabledev;
> > + }
>
> Can you keep your clocks disaled if the interface is not up?

I didn't get it will you please explain?

Regards,
Kedar.

>
> > +
> > + priv->can.clock.freq = clk_get_rate(priv->devclk);
> > +
> > + netif_napi_add(ndev, &priv->napi, xcan_rx_poll,
> > + priv->xcan_echo_skb_max_rx);
> > + ret = register_candev(ndev);
> > + if (ret) {
> > + dev_err(&pdev->dev, "fail to register failed (err=%d)\n",
> ret);
> > + goto err_unprepar_disableaper;
> > + }
> > +
> > + devm_can_led_init(ndev);
> > + dev_info(&pdev->dev,
> > + "reg_base=0x%p irq=%d clock=%d, tx fifo
> depth:%d\n",
> > + priv->reg_base, ndev->irq, priv->can.clock.freq,
> > + priv->xcan_echo_skb_max_tx);
> > +
> > + return 0;
> > +
> > +err_unprepar_disableaper:
> > + clk_disable_unprepare(priv->aperclk);
> > +err_unprepar_disabledev:
> > + clk_disable_unprepare(priv->devclk);
> > +err_free:
> > + free_candev(ndev);
> > +
> > + return ret;
> > +}
> > +
> > +/**
> > + * xcan_remove - Unregister the device after releasing the resources
> > + * @pdev: Handle to the platform device structure
> > + *
> > + * This function frees all the resources allocated to the device.
> > + * Return: 0 always
> > + */
> > +static int xcan_remove(struct platform_device *pdev) {
> > + struct net_device *ndev = platform_get_drvdata(pdev);
> > + struct xcan_priv *priv = netdev_priv(ndev);
> > +
> > + if (set_reset_mode(ndev) < 0)
> > + netdev_err(ndev, "mode resetting failed!\n");
> > +
> > + unregister_candev(ndev);
> > + netif_napi_del(&priv->napi);
> > + clk_disable_unprepare(priv->aperclk);
> > + clk_disable_unprepare(priv->devclk);
> > +
> > + free_candev(ndev);
> > +
> > + return 0;
> > +}
> > +
> > +/* Match table for OF platform binding */ static struct of_device_id
> > +xcan_of_match[] = {
> > + { .compatible = "xlnx,zynq-can-1.00.a", },
> > + { .compatible = "xlnx,axi-can-1.00.a", },
> > + { /* end of list */ },
> > +};
> > +MODULE_DEVICE_TABLE(of, xcan_of_match);
> > +
> > +static struct platform_driver xcan_driver = {
> > + .probe = xcan_probe,
> > + .remove = xcan_remove,
> > + .driver = {
> > + .owner = THIS_MODULE,
> > + .name = DRIVER_NAME,
> > + .pm = &xcan_dev_pm_ops,
> > + .of_match_table = xcan_of_match,
> > + },
> > +};
> > +
> > +module_platform_driver(xcan_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Xilinx Inc");
> > +MODULE_DESCRIPTION("Xilinx CAN interface");
> >
>
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Industrial Linux Solutions | Phone: +49-231-2826-924 |
> Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
> Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |

This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.

????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m????????????I?

2014-02-14 10:00:13

by Marc Kleine-Budde

[permalink] [raw]

Subject: Re: [PATCH v2] can: xilinx CAN controller support.

On 02/14/2014 10:36 AM, Appana Durga Kedareswara Rao wrote:
>>> +/* CAN register bit masks - XCAN_<REG>_<BIT>_MASK */
>>> +#define XCAN_SRR_CEN_MASK 0x00000002 /* CAN enable */
>>> +#define XCAN_SRR_RESET_MASK 0x00000001 /* Soft Reset the
>> CAN core */
>>> +#define XCAN_MSR_LBACK_MASK 0x00000002 /* Loop back
>> mode select */
>>> +#define XCAN_MSR_SLEEP_MASK 0x00000001 /* Sleep mode
>> select */
>>> +#define XCAN_BRPR_BRP_MASK 0x000000FF /* Baud rate
>> prescaler */
>>> +#define XCAN_BTR_SJW_MASK 0x00000180 /* Synchronous
>> jump width */
>>> +#define XCAN_BTR_TS2_MASK 0x00000070 /* Time segment
>> 2 */
>>> +#define XCAN_BTR_TS1_MASK 0x0000000F /* Time segment
>> 1 */
>>> +#define XCAN_ECR_REC_MASK 0x0000FF00 /* Receive error
>> counter */
>>> +#define XCAN_ECR_TEC_MASK 0x000000FF /* Transmit error
>> counter */
>>> +#define XCAN_ESR_ACKER_MASK 0x00000010 /* ACK error */
>>> +#define XCAN_ESR_BERR_MASK 0x00000008 /* Bit error */
>>> +#define XCAN_ESR_STER_MASK 0x00000004 /* Stuff error */
>>> +#define XCAN_ESR_FMER_MASK 0x00000002 /* Form error */
>>> +#define XCAN_ESR_CRCER_MASK 0x00000001 /* CRC error */
>>> +#define XCAN_SR_TXFLL_MASK 0x00000400 /* TX FIFO is full
>> */
>>> +#define XCAN_SR_ESTAT_MASK 0x00000180 /* Error status */
>>> +#define XCAN_SR_ERRWRN_MASK 0x00000040 /* Error warning
>> */
>>> +#define XCAN_SR_NORMAL_MASK 0x00000008 /* Normal mode
>> */
>>> +#define XCAN_SR_LBACK_MASK 0x00000002 /* Loop back
>> mode */
>>> +#define XCAN_SR_CONFIG_MASK 0x00000001 /* Configuration
>> mode */
>>> +#define XCAN_IXR_TXFEMP_MASK 0x00004000 /* TX FIFO Empty
>> */
>>> +#define XCAN_IXR_WKUP_MASK 0x00000800 /* Wake up
>> interrupt */
>>> +#define XCAN_IXR_SLP_MASK 0x00000400 /* Sleep
>> interrupt */
>>> +#define XCAN_IXR_BSOFF_MASK 0x00000200 /* Bus off
>> interrupt */
>>> +#define XCAN_IXR_ERROR_MASK 0x00000100 /* Error interrupt
>> */
>>> +#define XCAN_IXR_RXNEMP_MASK 0x00000080 /* RX FIFO
>> NotEmpty intr */
>>> +#define XCAN_IXR_RXOFLW_MASK 0x00000040 /* RX FIFO
>> Overflow intr */
>>> +#define XCAN_IXR_RXOK_MASK 0x00000010 /* Message
>> received intr */
>>> +#define XCAN_IXR_TXOK_MASK 0x00000002 /* TX successful
>> intr */
>>> +#define XCAN_IXR_ARBLST_MASK 0x00000001 /* Arbitration
>> lost intr */
>>> +#define XCAN_IDR_ID1_MASK 0xFFE00000 /* Standard msg
>> identifier */
>>> +#define XCAN_IDR_SRR_MASK 0x00100000 /* Substitute
>> remote TXreq */
>>> +#define XCAN_IDR_IDE_MASK 0x00080000 /* Identifier
>> extension */
>>> +#define XCAN_IDR_ID2_MASK 0x0007FFFE /* Extended
>> message ident */
>>> +#define XCAN_IDR_RTR_MASK 0x00000001 /* Remote TX
>> request */
>>> +#define XCAN_DLCR_DLC_MASK 0xF0000000 /* Data length
>> code */
>>> +
>
> Need to use BIT() Macro for the Masks?

You can, but it IMHO only makes sense where only a single bit is set.

[...]

>>> + int waiting_ech_skb_num;
>>> + int xcan_echo_skb_max_tx;
>>> + int xcan_echo_skb_max_rx;
>>> + struct napi_struct napi;
>>> + spinlock_t ech_skb_lock;
>>> + u32 (*read_reg)(const struct xcan_priv *priv, int reg);
>>> + void (*write_reg)(const struct xcan_priv *priv, int reg, u32 val);
>>
>> Please remove read_reg, write_reg, as long as there isn't any BE support in
>> the driver, call them directly.
>>
>
>
> As per yours and Michal discussion I am keeping this here (endianess
> of the IP is not fixed at compile time).

Ok.

[...]

>>> +/**
>>> + * xcan_start_xmit - Starts the transmission
>>> + * @skb: sk_buff pointer that contains data to be Txed
>>> + * @ndev: Pointer to net_device structure
>>> + *
>>> + * This function is invoked from upper layers to initiate
>>> +transmission. This
>>> + * function uses the next available free txbuff and populates their
>>> +fields to
>>> + * start the transmission.
>>> + *
>>> + * Return: 0 on success and failure value on error */ static int
>>> +xcan_start_xmit(struct sk_buff *skb, struct net_device *ndev) {
>>> + struct xcan_priv *priv = netdev_priv(ndev);
>>> + struct net_device_stats *stats = &ndev->stats;
>>> + struct can_frame *cf = (struct can_frame *)skb->data;
>>> + u32 id, dlc, data[2] = {0, 0}, rtr = 0;
>>
>> I think you can drop the rtr varibale and use cf->can_id & CAN_RTR_FLAG
>> instead.
>>
>
> OK
>>> + unsigned long flags;
>>> +
>>> + if (can_dropped_invalid_skb(ndev, skb))
>>> + return NETDEV_TX_OK;
>>> +
>>> + /* Watch carefully on the bit sequence */
>>> + if (cf->can_id & CAN_EFF_FLAG) {
>>> + /* Extended CAN ID format */
>>> + id = ((cf->can_id & CAN_EFF_MASK) << XCAN_IDR_ID2_SHIFT)
>> &
>>> + XCAN_IDR_ID2_MASK;
>>> + id |= (((cf->can_id & CAN_EFF_MASK) >>
>>> + (CAN_EFF_ID_BITS-CAN_SFF_ID_BITS)) <<
>>> + XCAN_IDR_ID1_SHIFT) & XCAN_IDR_ID1_MASK;
>>> +
>>> + /* The substibute remote TX request bit should be "1"
>>> + * for extended frames as in the Xilinx CAN datasheet
>>> + */
>>> + id |= XCAN_IDR_IDE_MASK | XCAN_IDR_SRR_MASK;
>>> +
>>> + if (cf->can_id & CAN_RTR_FLAG) {
>>> + /* Extended frames remote TX request */
>>> + id |= XCAN_IDR_RTR_MASK;
>>> + rtr = 1;
>>> + }
>>> + } else {
>>> + /* Standard CAN ID format */
>>> + id = ((cf->can_id & CAN_SFF_MASK) << XCAN_IDR_ID1_SHIFT)
>> &
>>> + XCAN_IDR_ID1_MASK;
>>> +
>>> + if (cf->can_id & CAN_RTR_FLAG) {
>>> + /* Extended frames remote TX request */
>>> + id |= XCAN_IDR_SRR_MASK;
>>> + rtr = 1;
>>> + }
>>> + }
>>> +
>>> + dlc = (cf->can_dlc & 0xf) << XCAN_DLCR_DLC_SHIFT;
>>
>> No need to mask dlc, it's valid.
>>
> OK
>
>>> +
>>> + if (dlc > 0)
>>
>> You've copied my speudo code :)
>> But you have to use (cf->can_dlc > 0) here, as dlc is the shifted value.
>
> Yes :) I missed it will change
>
>>
>>> + data[0] = be32_to_cpup((__be32 *)(cf->data + 0));
>>> + if (dlc > 4)
>>> + data[1] = be32_to_cpup((__be32 *)(cf->data + 4));
>>> +
>>> + can_put_echo_skb(skb, ndev, priv->ech_skb_next);
>>
>> can_put_echo_skb(skb, ndev,
>> priv->tx_head % priv->xcan_echo_skb_max_tx);
>>
>> priv->tx_head++;
>>
>
> Ok
>>> +
>>> + /* Write the Frame to Xilinx CAN TX FIFO */
>>> + priv->write_reg(priv, XCAN_TXFIFO_ID_OFFSET, id);
>>> + priv->write_reg(priv, XCAN_TXFIFO_DLC_OFFSET, dlc);
>>> + if (!rtr) {
>>> + priv->write_reg(priv, XCAN_TXFIFO_DW1_OFFSET, data[0]);
>>> + priv->write_reg(priv, XCAN_TXFIFO_DW2_OFFSET, data[1]);
>>> + stats->tx_bytes += cf->can_dlc;
>>
>> Please add a comment which write triggers the tx. What in case of the rtr?
>> Which write triggers the tx then?
>>
>
> Ok Will Add
>
> In RTR Case the below write triggers the trasmission
> priv->write_reg(priv, XCAN_TXFIFO_DLC_OFFSET, dlc);
> In Normal case this write
> priv->write_reg(priv, XCAN_TXFIFO_DW2_OFFSET, data[1]);
> Triggers the transmission.
>
> In Btw: Due to the limitations in the IP( Tx DLC register is a write only Register)
> I can't put this stats->tx_bytes += cf->can_dlc; in the tx interrupt routine.

No problem.

[...]

>>> + if (work_done < quota) {
>>> + napi_complete(napi);
>>> + ier = priv->read_reg(priv, XCAN_IER_OFFSET);
>>> + ier |= (XCAN_IXR_RXOK_MASK |
>> XCAN_IXR_RXNEMP_MASK);
>>> + priv->write_reg(priv, XCAN_IER_OFFSET, ier);
>>
>> Is this a read-modify-write register? I mean will an interrupt get disabled, if
>> you write a 0-bit in the IER register? What does the ICR register?
>
> ISR- Interrupt Status Register (Read only register)
> IER- Interrupt Enable Register(R/w register)
> ICR- Interrupt Clear Register.(write only register)
>
>
> The Interrupt Status Register (ISR) contains bits that are set when a particular interrupt condition occurs. If
> the corresponding mask bit in the Interrupt Enable Register is set, an interrupt is generated.
> Interrupt bits in the ISR can be cleared by writing to the Interrupt Clear Register

Thanks.

[...]

>>> +/**
>>> + * xcan_open - Driver open routine
>>> + * @ndev: Pointer to net_device structure
>>> + *
>>> + * This is the driver open routine.
>>> + * Return: 0 on success and failure value on error */ static int
>>> +xcan_open(struct net_device *ndev) {
>>> + struct xcan_priv *priv = netdev_priv(ndev);
>>> + int ret;
>>> +
>>> + ret = request_irq(ndev->irq, xcan_interrupt, priv->irq_flags,
>>> + ndev->name, (void *)ndev);
>>> + if (ret < 0) {
>>> + netdev_err(ndev, "Irq allocation for CAN failed\n");
>>> + return ret;
>>> + }
>>> +
>>> + /* Set chip into reset mode */
>>> + ret = set_reset_mode(ndev);
>>> + if (ret < 0)
>>> + netdev_err(ndev, "mode resetting failed failed!\n");
>>
>> Is this critical?
>
> This condition usually won't fail.
> But if the controller has a problems at the h/w level in that case putted this err print.
> If you want me to change it as a warning will do

If there is a hardware level problem, is it better to return here with
an error (and free the IRQ)?

[...]

>>> +/**
>>> + * xcan_probe - Platform registration call
>>> + * @pdev: Handle to the platform device structure
>>> + *
>>> + * This function does all the memory allocation and registration for
>>> +the CAN
>>> + * device.
>>> + *
>>> + * Return: 0 on success and failure value on error */ static int
>>> +xcan_probe(struct platform_device *pdev) {
>>> + struct resource *res; /* IO mem resources */
>>> + struct net_device *ndev;
>>> + struct xcan_priv *priv;
>>> + int ret, fifodep;
>>> +
>>> + /* Create a CAN device instance */
>>> + ndev = alloc_candev(sizeof(struct xcan_priv),
>> XCAN_ECHO_SKB_MAX);
>>> + if (!ndev)
>>> + return -ENOMEM;
>>> +
>>> + priv = netdev_priv(ndev);
>>> + priv->dev = ndev;
>>> + priv->can.bittiming_const = &xcan_bittiming_const;
>>> + priv->can.do_set_bittiming = xcan_set_bittiming;
>>> + priv->can.do_set_mode = xcan_do_set_mode;
>>> + priv->can.do_get_berr_counter = xcan_get_berr_counter;
>>> + priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
>>> + CAN_CTRLMODE_BERR_REPORTING;
>>> +
>>> + /* Get IRQ for the device */
>>> + ndev->irq = platform_get_irq(pdev, 0);
>>> +
>>> + spin_lock_init(&priv->ech_skb_lock);
>>> + ndev->flags |= IFF_ECHO; /* We support local echo */
>>> +
>>> + platform_set_drvdata(pdev, ndev);
>>> + SET_NETDEV_DEV(ndev, &pdev->dev);
>>> + ndev->netdev_ops = &xcan_netdev_ops;
>>> +
>>> + /* Get the virtual base address for the device */
>>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> + priv->reg_base = devm_ioremap_resource(&pdev->dev, res);
>>> + if (IS_ERR(priv->reg_base)) {
>>> + ret = PTR_ERR(priv->reg_base);
>>> + goto err_free;
>>> + }
>>> + ndev->mem_start = res->start;
>>> + ndev->mem_end = res->end;
>>> +
>>> + priv->write_reg = xcan_write_reg;
>>> + priv->read_reg = xcan_read_reg;
>>> +
>>> + ret = of_property_read_u32(pdev->dev.of_node, "tx-fifo-depth",
>>> + &fifodep);
>>> + if (ret < 0)
>>> + goto err_free;
>>> + priv->xcan_echo_skb_max_tx = fifodep;
>>> +
>>> + ret = of_property_read_u32(pdev->dev.of_node, "rx-fifo-depth",
>>> + &fifodep);
>>> + if (ret < 0)
>>> + goto err_free;
>>> + priv->xcan_echo_skb_max_rx = fifodep;
>>> +
>>> + /* Getting the CAN devclk info */
>>> + priv->devclk = devm_clk_get(&pdev->dev, "ref_clk");
>>> + if (IS_ERR(priv->devclk)) {
>>> + dev_err(&pdev->dev, "Device clock not found.\n");
>>> + ret = PTR_ERR(priv->devclk);
>>> + goto err_free;
>>> + }
>>> +
>>> + /* Check for type of CAN device */
>>> + if (of_device_is_compatible(pdev->dev.of_node,
>>> + "xlnx,zynq-can-1.00.a")) {
>>> + priv->aperclk = devm_clk_get(&pdev->dev, "aper_clk");
>>> + if (IS_ERR(priv->aperclk)) {
>>> + dev_err(&pdev->dev, "aper clock not found\n");
>>> + ret = PTR_ERR(priv->aperclk);
>>> + goto err_free;
>>> + }
>>> + } else {
>>> + priv->aperclk = priv->devclk;
>>> + }
>>> +
>>> + ret = clk_prepare_enable(priv->devclk);
>>> + if (ret) {
>>> + dev_err(&pdev->dev, "unable to enable device clock\n");
>>> + goto err_free;
>>> + }
>>> +
>>> + ret = clk_prepare_enable(priv->aperclk);
>>> + if (ret) {
>>> + dev_err(&pdev->dev, "unable to enable aper clock\n");
>>> + goto err_unprepar_disabledev;
>>> + }
>>
>> Can you keep your clocks disaled if the interface is not up?
>
> I didn't get it will you please explain?

This feature s optional, but a a good practice.

This function gets called when the driver is loaded, i.e. during boot.
So the complete CAN core will be enabled and powered, even if the
interface is down. To reduce power consumption it's better to enable the
clocks in the open() function and disable in close(). If you access some
CAN registers during probe you have to enable the clock and you probably
have to enable it in the do_get_berr_counter callback, as it may be
called if the interface is still down.

Marc

--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |

Attachments:

signature.asc (242.00 B)
OpenPGP digital signature