Driver for the native I2C adapter found in Rockchip RK3xxx SoCs.
Configuration is only possible through devicetree. The driver is
interrupt driven and supports the I2C_M_IGNORE_NAK mangling bit.
Signed-off-by: Max Schwarz <[email protected]>
---
The driver cannot be used without a proper clock driver
supporting rate calculation, such as Heiko St?bner's RK3xxx clock
driver series [1].
Changes since v4:
- fixed a bug in message counting in rk3x_i2c_xfer()
- Found/suggested by Wolfram Sang:
* fixed style issues
* fixed sorting in Kconfig, Makefile
* removed unneeded fields from struct rk3x_i2c
* REPEATED_START between msgs of one transfer
* fixed wrong error code on NAK
* support for SMB_QUICK (len == 0)
* removed unneeded DT check & alias handling
* sanity check for clock-frequency
Changes since v3:
- fixed style issues found by Maxime Ripard
- use dt alias id to calculate the bit offset in GRF,
as suggested by Maxime Ripard
- also use dt alias id for i2c_add_numbered_adapter()
Changes since v2:
- support for the new GRF syscon mapping by Heiko St?bner
- probe error handling improvements by Heiko St?bner
- fixed wrong remove() order found by Heiko St?bner
- removed unnecessary clk_enable() during probe
- removed switch back to old interface during remove
Changes since v1:
- dt property names "rockchip,*" suggested by Heiko St?bner
- fixed overly specific RK3188 comment (Heiko St?bner)
The dts files needed for testing on Radxa Rock are in my tree at
https://github.com/xqms/linux.git topic/i2c-rk3x-clean-v4
[1]: http://www.spinics.net/lists/arm-kernel/msg329102.html
Documentation/devicetree/bindings/i2c/i2c-rk3x.txt | 42 ++
drivers/i2c/busses/Kconfig | 10 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-rk3x.c | 769 +++++++++++++++++++++
4 files changed, 822 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
create mode 100644 drivers/i2c/busses/i2c-rk3x.c
diff --git a/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt b/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
new file mode 100644
index 0000000..dde6c22
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
@@ -0,0 +1,42 @@
+* Rockchip RK3xxx I2C controller
+
+This driver interfaces with the native I2C controller present in Rockchip
+RK3xxx SoCs.
+
+Required properties :
+
+ - reg : Offset and length of the register set for the device
+ - compatible : should be "rockchip,rk3066-i2c", "rockchip,rk3188-i2c" or
+ "rockchip,rk3288-i2c".
+ - interrupts : interrupt number
+ - clocks : parent clock
+
+Required on RK3066, RK3188 :
+
+ - rockchip,grf : the phandle of the syscon node for the general register
+ file (GRF)
+ - on those SoCs an alias with the correct I2C bus ID (bit offset in the GRF)
+ is also required.
+
+Optional properties :
+
+ - clock-frequency : SCL frequency to use (in Hz). If omitted, 100kHz is used.
+
+Example:
+
+aliases {
+ i2c0 = &i2c0;
+}
+
+i2c0: i2c@2002d000 {
+ compatible = "rockchip,rk3188-i2c";
+ reg = <0x2002d000 0x1000>;
+ interrupts = <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ rockchip,grf = <&grf>;
+
+ clock-names = "i2c";
+ clocks = <&cru PCLK_I2C0>;
+};
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 7ccc51e..39307d0 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -676,6 +676,16 @@ config I2C_RIIC
This driver can also be built as a module. If so, the module
will be called i2c-riic.
+config I2C_RK3X
+ tristate "Rockchip RK3xxx I2C adapter"
+ depends on OF
+ help
+ Say Y here to include support for the I2C adapter in Rockchip RK3xxx
+ SoCs.
+
+ This driver can also be built as a module. If so, the module will
+ be called i2c-rk3x.
+
config HAVE_S3C2410_I2C
bool
help
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 413d062..5582cf9 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -66,6 +66,7 @@ obj-$(CONFIG_I2C_PXA) += i2c-pxa.o
obj-$(CONFIG_I2C_PXA_PCI) += i2c-pxa-pci.o
obj-$(CONFIG_I2C_QUP) += i2c-qup.o
obj-$(CONFIG_I2C_RIIC) += i2c-riic.o
+obj-$(CONFIG_I2C_RK3X) += i2c-rk3x.o
obj-$(CONFIG_I2C_S3C2410) += i2c-s3c2410.o
obj-$(CONFIG_I2C_S6000) += i2c-s6000.o
obj-$(CONFIG_I2C_SH7760) += i2c-sh7760.o
diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
new file mode 100644
index 0000000..7a430f4
--- /dev/null
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -0,0 +1,769 @@
+/*
+ * Driver for I2C adapter in Rockchip RK3xxx SoC
+ *
+ * Max Schwarz <[email protected]>
+ * based on the patches by Rockchip Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <linux/i2c.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/spinlock.h>
+#include <linux/clk.h>
+#include <linux/wait.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+
+/* Register Map */
+#define REG_CON 0x00 /* control register */
+#define REG_CLKDIV 0x04 /* clock divisor register */
+#define REG_MRXADDR 0x08 /* slave address for REGISTER_TX */
+#define REG_MRXRADDR 0x0c /* slave register address for REGISTER_TX */
+#define REG_MTXCNT 0x10 /* number of bytes to be transmitted */
+#define REG_MRXCNT 0x14 /* number of bytes to be received */
+#define REG_IEN 0x18 /* interrupt enable */
+#define REG_IPD 0x1c /* interrupt pending */
+#define REG_FCNT 0x20 /* finished count */
+
+/* Data buffer offsets */
+#define TXBUFFER_BASE 0x100
+#define RXBUFFER_BASE 0x200
+
+/* REG_CON bits */
+#define REG_CON_EN BIT(0)
+enum {
+ REG_CON_MOD_TX = 0, /* transmit data */
+ REG_CON_MOD_REGISTER_TX, /* select register and restart */
+ REG_CON_MOD_RX, /* receive data */
+ REG_CON_MOD_REGISTER_RX, /* broken: transmits read addr AND writes
+ * register addr */
+};
+#define REG_CON_MOD(mod) ((mod) << 1)
+#define REG_CON_MOD_MASK (BIT(1) | BIT(2))
+#define REG_CON_START BIT(3)
+#define REG_CON_STOP BIT(4)
+#define REG_CON_LASTACK BIT(5) /* 1: do not send ACK after last receive */
+#define REG_CON_ACTACK BIT(6) /* 1: stop if NACK is received */
+
+/* REG_MRXADDR bits */
+#define REG_MRXADDR_VALID(x) BIT(24 + (x)) /* [x*8+7:x*8] of MRX[R]ADDR valid */
+
+/* REG_IEN/REG_IPD bits */
+#define REG_INT_BTF BIT(0) /* a byte was transmitted */
+#define REG_INT_BRF BIT(1) /* a byte was received */
+#define REG_INT_MBTF BIT(2) /* master data transmit finished */
+#define REG_INT_MBRF BIT(3) /* master data receive finished */
+#define REG_INT_START BIT(4) /* START condition generated */
+#define REG_INT_STOP BIT(5) /* STOP condition generated */
+#define REG_INT_NAKRCV BIT(6) /* NACK received */
+#define REG_INT_ALL 0x7f
+
+/* Constants */
+#define WAIT_TIMEOUT 200 /* ms */
+#define DEFAULT_SCL_RATE (100 * 1000) /* Hz */
+
+enum rk3x_i2c_state {
+ STATE_IDLE,
+ STATE_START,
+ STATE_READ,
+ STATE_WRITE,
+ STATE_STOP
+};
+
+/**
+ * @grf_offset: offset inside the grf regmap for setting the i2c type
+ */
+struct rk3x_i2c_soc_data {
+ int grf_offset;
+};
+
+struct rk3x_i2c {
+ struct i2c_adapter adap;
+ struct device *dev;
+ struct rk3x_i2c_soc_data *soc_data;
+
+ /* Hardware resources */
+ void __iomem *regs;
+ struct clk *clk;
+
+ /* Settings */
+ unsigned int scl_frequency;
+
+ /* Synchronization & notification */
+ spinlock_t lock;
+ wait_queue_head_t wait;
+ bool busy;
+
+ /* Current message */
+ struct i2c_msg *msg;
+ u8 addr;
+ unsigned int mode;
+ bool is_last_msg;
+
+ /* I2C state machine */
+ enum rk3x_i2c_state state;
+ unsigned int processed; /* sent/received bytes */
+ int error;
+};
+
+static inline void i2c_writel(struct rk3x_i2c *i2c, u32 value,
+ unsigned int offset)
+{
+ writel(value, i2c->regs + offset);
+}
+
+static inline u32 i2c_readl(struct rk3x_i2c *i2c, unsigned int offset)
+{
+ return readl(i2c->regs + offset);
+}
+
+/* Reset all interrupt pending bits */
+static inline void rk3x_i2c_clean_ipd(struct rk3x_i2c *i2c)
+{
+ i2c_writel(i2c, REG_INT_ALL, REG_IPD);
+}
+
+/**
+ * Generate a START condition, which triggers a REG_INT_START interrupt.
+ */
+static void rk3x_i2c_start(struct rk3x_i2c *i2c)
+{
+ u32 val;
+
+ dev_dbg(i2c->dev, "start\n");
+
+ rk3x_i2c_clean_ipd(i2c);
+ i2c_writel(i2c, REG_INT_START, REG_IEN);
+
+ /* enable adapter with correct mode, send START condition */
+ val = REG_CON_EN | REG_CON_MOD(i2c->mode) | REG_CON_START;
+
+ /* if we want to react to NACK, set ACTACK bit */
+ if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
+ val |= REG_CON_ACTACK;
+
+ i2c_writel(i2c, val, REG_CON);
+}
+
+/**
+ * Generate a STOP condition, which triggers a REG_INT_STOP interrupt.
+ *
+ * @error: Error code to return in rk3x_i2c_xfer
+ */
+static void rk3x_i2c_stop(struct rk3x_i2c *i2c, int error)
+{
+ unsigned int ctrl;
+
+ i2c->processed = 0;
+ i2c->msg = 0;
+ i2c->error = error;
+
+ if (i2c->is_last_msg) {
+ /* Enable stop interrupt */
+ i2c_writel(i2c, REG_INT_STOP, REG_IEN);
+
+ i2c->state = STATE_STOP;
+
+ ctrl = i2c_readl(i2c, REG_CON);
+ ctrl |= REG_CON_STOP;
+ i2c_writel(i2c, ctrl, REG_CON);
+ } else {
+ /* Signal rk3x_i2c_xfer to start the next message. */
+ i2c->busy = 0;
+ i2c->state = STATE_IDLE;
+
+ /*
+ * The HW is actually not capable of REPEATED START. But we can
+ * get the intended effect by resetting its internal state
+ * and issuing an ordinary START.
+ */
+ i2c_writel(i2c, 0, REG_CON);
+
+ /* signal that we are finished with the current msg */
+ wake_up(&i2c->wait);
+ }
+}
+
+/**
+ * Setup a read according to i2c->msg
+ */
+static void rk3x_i2c_prepare_read(struct rk3x_i2c *i2c)
+{
+ unsigned int len = i2c->msg->len - i2c->processed;
+ u32 con;
+
+ con = i2c_readl(i2c, REG_CON);
+
+ /*
+ * The hw can read up to 32 bytes at a time. If we need more than one
+ * chunk, send an ACK after the last byte of the current chunk.
+ */
+ if (unlikely(len > 32)) {
+ len = 32;
+ con &= ~REG_CON_LASTACK;
+ } else {
+ con |= REG_CON_LASTACK;
+ }
+
+ /* make sure we are in plain RX mode if we read a second chunk */
+ if (i2c->processed != 0) {
+ con &= ~REG_CON_MOD_MASK;
+ con |= REG_CON_MOD(REG_CON_MOD_RX);
+ }
+
+ i2c_writel(i2c, con, REG_CON);
+ i2c_writel(i2c, len, REG_MRXCNT);
+}
+
+/**
+ * Fill the transmit buffer with data from i2c->msg
+ */
+static void rk3x_i2c_fill_transmit_buf(struct rk3x_i2c *i2c)
+{
+ unsigned int i, j;
+ u32 cnt = 0;
+ u32 val;
+ u8 byte;
+
+ for (i = 0; i < 8; ++i) {
+ val = 0;
+ for (j = 0; j < 4; ++j) {
+ if (i2c->processed == i2c->msg->len)
+ break;
+
+ if (i2c->processed == 0 && cnt == 0)
+ byte = (i2c->addr & 0x7f) << 1;
+ else
+ byte = i2c->msg->buf[i2c->processed++];
+
+ val |= byte << (j * 8);
+ cnt++;
+ }
+
+ i2c_writel(i2c, val, TXBUFFER_BASE + 4 * i);
+
+ if (i2c->processed == i2c->msg->len)
+ break;
+ }
+
+ i2c_writel(i2c, cnt, REG_MTXCNT);
+}
+
+
+/* IRQ handlers for individual states */
+
+static void rk3x_i2c_handle_start(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+ if (!(ipd & REG_INT_START)) {
+ rk3x_i2c_stop(i2c, -EIO);
+ dev_warn(i2c->dev, "unexpected irq in START: 0x%x\n", ipd);
+ rk3x_i2c_clean_ipd(i2c);
+ return;
+ }
+
+ /* ack interrupt */
+ i2c_writel(i2c, REG_INT_START, REG_IPD);
+
+ /* disable start bit */
+ i2c_writel(i2c, i2c_readl(i2c, REG_CON) & ~REG_CON_START, REG_CON);
+
+ /* enable appropriate interrupts and transition */
+ if (i2c->mode == REG_CON_MOD_TX) {
+ i2c_writel(i2c, REG_INT_MBTF | REG_INT_NAKRCV, REG_IEN);
+ i2c->state = STATE_WRITE;
+ rk3x_i2c_fill_transmit_buf(i2c);
+ } else {
+ /* in any other case, we are going to be reading. */
+ i2c_writel(i2c, REG_INT_MBRF | REG_INT_NAKRCV, REG_IEN);
+ i2c->state = STATE_READ;
+ rk3x_i2c_prepare_read(i2c);
+ }
+}
+
+static void rk3x_i2c_handle_write(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+ if (!(ipd & REG_INT_MBTF)) {
+ rk3x_i2c_stop(i2c, -EIO);
+ dev_err(i2c->dev, "unexpected irq in WRITE: 0x%x\n", ipd);
+ rk3x_i2c_clean_ipd(i2c);
+ return;
+ }
+
+ /* ack interrupt */
+ i2c_writel(i2c, REG_INT_MBTF, REG_IPD);
+
+ /* are we finished? */
+ if (i2c->processed == i2c->msg->len)
+ rk3x_i2c_stop(i2c, i2c->error);
+ else
+ rk3x_i2c_fill_transmit_buf(i2c);
+}
+
+static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+ unsigned int i;
+ unsigned int len = i2c->msg->len - i2c->processed;
+ unsigned int val;
+ u8 byte;
+
+ /* we only care for MBRF here. */
+ if (!(ipd & REG_INT_MBRF))
+ return;
+
+ /* ack interrupt */
+ i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
+
+ /* read the data from receive buffer */
+ for (i = 0; i < len; ++i) {
+ if (i % 4 == 0)
+ val = i2c_readl(i2c, RXBUFFER_BASE + (i / 4) * 4);
+
+ byte = (val >> ((i % 4) * 8)) & 0xff;
+ i2c->msg->buf[i2c->processed++] = byte;
+ }
+
+ /* are we finished? */
+ if (i2c->processed == i2c->msg->len)
+ rk3x_i2c_stop(i2c, i2c->error);
+ else
+ rk3x_i2c_prepare_read(i2c);
+}
+
+static void rk3x_i2c_handle_stop(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+ unsigned int con;
+
+ if (!(ipd & REG_INT_STOP)) {
+ rk3x_i2c_stop(i2c, -EIO);
+ dev_err(i2c->dev, "unexpected irq in STOP: 0x%x\n", ipd);
+ rk3x_i2c_clean_ipd(i2c);
+ return;
+ }
+
+ /* ack interrupt */
+ i2c_writel(i2c, REG_INT_STOP, REG_IPD);
+
+ /* disable STOP bit */
+ con = i2c_readl(i2c, REG_CON);
+ con &= ~REG_CON_STOP;
+ i2c_writel(i2c, con, REG_CON);
+
+ i2c->busy = 0;
+ i2c->state = STATE_IDLE;
+
+ /* signal rk3x_i2c_xfer that we are finished */
+ wake_up(&i2c->wait);
+}
+
+static irqreturn_t rk3x_i2c_irq(int irqno, void *dev_id)
+{
+ struct rk3x_i2c *i2c = dev_id;
+ unsigned int ipd;
+
+ spin_lock(&i2c->lock);
+
+ ipd = i2c_readl(i2c, REG_IPD);
+ if (i2c->state == STATE_IDLE) {
+ dev_warn(i2c->dev, "irq in STATE_IDLE, ipd = 0x%x\n", ipd);
+ rk3x_i2c_clean_ipd(i2c);
+ goto out;
+ }
+
+ dev_dbg(i2c->dev, "IRQ: state %d, ipd: %x\n", i2c->state, ipd);
+
+ /* Clean interrupt bits we don't care about */
+ ipd &= ~(REG_INT_BRF | REG_INT_BTF);
+
+ if (ipd & REG_INT_NAKRCV) {
+ /*
+ * We got a NACK in the last operation. Depending on whether
+ * IGNORE_NAK is set, we have to stop the operation and report
+ * an error.
+ */
+ i2c_writel(i2c, REG_INT_NAKRCV, REG_IPD);
+
+ ipd &= ~REG_INT_NAKRCV;
+
+ if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
+ rk3x_i2c_stop(i2c, -ENXIO);
+ }
+
+ /* is there anything left to handle? */
+ if (unlikely(ipd == 0))
+ goto out;
+
+ switch (i2c->state) {
+ case STATE_START:
+ rk3x_i2c_handle_start(i2c, ipd);
+ break;
+ case STATE_WRITE:
+ rk3x_i2c_handle_write(i2c, ipd);
+ break;
+ case STATE_READ:
+ rk3x_i2c_handle_read(i2c, ipd);
+ break;
+ case STATE_STOP:
+ rk3x_i2c_handle_stop(i2c, ipd);
+ break;
+ case STATE_IDLE:
+ break;
+ }
+
+out:
+ spin_unlock(&i2c->lock);
+ return IRQ_HANDLED;
+}
+
+static void rk3x_i2c_set_scl_rate(struct rk3x_i2c *i2c, unsigned long scl_rate)
+{
+ unsigned long i2c_rate = clk_get_rate(i2c->clk);
+ unsigned int div;
+
+ /* SCL rate = (clk rate) / (8 * DIV) */
+ div = DIV_ROUND_UP(i2c_rate, scl_rate * 8);
+
+ /* The lower and upper half of the CLKDIV reg describe the length of
+ * SCL low & high periods. */
+ div = DIV_ROUND_UP(div, 2);
+
+ i2c_writel(i2c, (div << 16) | (div & 0xffff), REG_CLKDIV);
+}
+
+/**
+ * Setup I2C registers for an I2C operation specified by msgs, num.
+ *
+ * Must be called with i2c->lock held.
+ *
+ * @msgs: I2C msgs to process
+ * @num: Number of msgs
+ *
+ * returns: Number of I2C msgs processed or negative in case of error
+ */
+static int rk3x_i2c_setup(struct rk3x_i2c *i2c, struct i2c_msg *msgs, int num)
+{
+ u32 addr = (msgs[0].addr & 0x7f) << 1;
+ int ret = 0;
+
+ /*
+ * The I2C adapter can issue a small (len < 4) write packet before
+ * reading. This speeds up SMBus-style register reads.
+ * The MRXADDR/MRXRADDR hold the slave address and the slave register
+ * address in this case.
+ */
+
+ if (num >= 2 && msgs[0].len < 4
+ && !(msgs[0].flags & I2C_M_RD)
+ && (msgs[1].flags & I2C_M_RD)) {
+ u32 reg_addr = 0;
+ int i;
+
+ dev_dbg(i2c->dev, "Combined write/read from addr 0x%x\n",
+ addr >> 1);
+
+ /* Fill MRXRADDR with the register address(es) */
+ for (i = 0; i < msgs[0].len; ++i) {
+ reg_addr |= msgs[0].buf[i] << (i * 8);
+ reg_addr |= REG_MRXADDR_VALID(i);
+ }
+
+ /* msgs[0] is handled by hw. */
+ i2c->msg = &msgs[1];
+
+ i2c->mode = REG_CON_MOD_REGISTER_TX;
+
+ i2c_writel(i2c, addr | REG_MRXADDR_VALID(0), REG_MRXADDR);
+ i2c_writel(i2c, reg_addr, REG_MRXRADDR);
+
+ ret = 2;
+ } else {
+ /*
+ * We'll have to do it the boring way and process the msgs
+ * one-by-one.
+ */
+
+ if (msgs[0].flags & I2C_M_RD) {
+ addr |= 1; /* set read bit */
+
+ /*
+ * We have to transmit the slave addr first. Use
+ * MOD_REGISTER_TX for that purpose.
+ */
+ i2c->mode = REG_CON_MOD_REGISTER_TX;
+ i2c_writel(i2c, addr | REG_MRXADDR_VALID(0),
+ REG_MRXADDR);
+ i2c_writel(i2c, 0, REG_MRXRADDR);
+ } else {
+ i2c->mode = REG_CON_MOD_TX;
+ }
+
+ i2c->msg = &msgs[0];
+
+ ret = 1;
+ }
+
+ i2c->addr = msgs[0].addr;
+ i2c->busy = true;
+ i2c->state = STATE_START;
+ i2c->processed = 0;
+ i2c->error = 0;
+
+ rk3x_i2c_clean_ipd(i2c);
+
+ return ret;
+}
+
+static int rk3x_i2c_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ struct rk3x_i2c *i2c = (struct rk3x_i2c *)adap->algo_data;
+ unsigned long timeout, flags;
+ int ret = 0;
+ int i;
+
+ spin_lock_irqsave(&i2c->lock, flags);
+
+ clk_enable(i2c->clk);
+
+ /* The clock rate might have changed, so setup the divider again */
+ rk3x_i2c_set_scl_rate(i2c, i2c->scl_frequency);
+
+ i2c->is_last_msg = false;
+
+ /*
+ * Process msgs. We can handle more than one message at once (see
+ * rk3x_i2c_setup()).
+ */
+ for (i = 0; i < num; i += ret) {
+ ret = rk3x_i2c_setup(i2c, msgs + i, num - i);
+
+ if (ret < 0) {
+ dev_err(i2c->dev, "rk3x_i2c_setup() failed\n");
+ break;
+ }
+
+ if (i + ret >= num)
+ i2c->is_last_msg = true;
+
+ spin_unlock_irqrestore(&i2c->lock, flags);
+
+ rk3x_i2c_start(i2c);
+
+ timeout = wait_event_timeout(i2c->wait, !i2c->busy,
+ msecs_to_jiffies(WAIT_TIMEOUT));
+
+ spin_lock_irqsave(&i2c->lock, flags);
+
+ if (timeout == 0) {
+ dev_err(i2c->dev, "timeout, ipd: 0x%02x, state: %d\n",
+ i2c_readl(i2c, REG_IPD), i2c->state);
+
+ /* Force a STOP condition without interrupt */
+ i2c_writel(i2c, 0, REG_IEN);
+ i2c_writel(i2c, REG_CON_EN | REG_CON_STOP, REG_CON);
+
+ i2c->state = STATE_IDLE;
+
+ ret = -ETIMEDOUT;
+ break;
+ }
+
+ if (i2c->error) {
+ ret = i2c->error;
+ break;
+ }
+ }
+
+ clk_disable(i2c->clk);
+ spin_unlock_irqrestore(&i2c->lock, flags);
+
+ return ret;
+}
+
+static u32 rk3x_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
+}
+
+static const struct i2c_algorithm rk3x_i2c_algorithm = {
+ .master_xfer = rk3x_i2c_xfer,
+ .functionality = rk3x_i2c_func,
+};
+
+static struct rk3x_i2c_soc_data soc_data[3] = {
+ { .grf_offset = 0x154 }, /* rk3066 */
+ { .grf_offset = 0x0a4 }, /* rk3188 */
+ { .grf_offset = -1 }, /* no I2C switching needed */
+};
+
+static const struct of_device_id rk3x_i2c_match[] = {
+ { .compatible = "rockchip,rk3066-i2c", .data = (void *)&soc_data[0] },
+ { .compatible = "rockchip,rk3188-i2c", .data = (void *)&soc_data[1] },
+ { .compatible = "rockchip,rk3288-i2c", .data = (void *)&soc_data[2] },
+};
+
+static int rk3x_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ const struct of_device_id *match;
+ struct rk3x_i2c *i2c;
+ struct resource *mem;
+ int ret = 0;
+ int bus_nr;
+ u32 value;
+ int irq;
+
+ i2c = devm_kzalloc(&pdev->dev, sizeof(struct rk3x_i2c), GFP_KERNEL);
+ if (!i2c)
+ return -ENOMEM;
+
+ match = of_match_node(rk3x_i2c_match, np);
+ i2c->soc_data = (struct rk3x_i2c_soc_data *)match->data;
+
+ if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+ &i2c->scl_frequency)) {
+ dev_info(&pdev->dev, "using default SCL frequency: %d\n",
+ DEFAULT_SCL_RATE);
+ i2c->scl_frequency = DEFAULT_SCL_RATE;
+ }
+
+ if (i2c->scl_frequency == 0 || i2c->scl_frequency > 400 * 1000) {
+ dev_warn(&pdev->dev, "invalid SCL frequency specified.\n");
+ dev_warn(&pdev->dev, "using default SCL frequency: %d\n",
+ DEFAULT_SCL_RATE);
+ i2c->scl_frequency = DEFAULT_SCL_RATE;
+ }
+
+ strlcpy(i2c->adap.name, "rk3x-i2c", sizeof(i2c->adap.name));
+ i2c->adap.owner = THIS_MODULE;
+ i2c->adap.algo = &rk3x_i2c_algorithm;
+ i2c->adap.retries = 3;
+ i2c->adap.dev.of_node = np;
+ i2c->adap.algo_data = i2c;
+ i2c->adap.dev.parent = &pdev->dev;
+
+ i2c->dev = &pdev->dev;
+
+ spin_lock_init(&i2c->lock);
+ init_waitqueue_head(&i2c->wait);
+
+ i2c->clk = devm_clk_get(&pdev->dev, 0);
+ if (IS_ERR(i2c->clk)) {
+ dev_err(&pdev->dev, "cannot get clock\n");
+ return PTR_ERR(i2c->clk);
+ }
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
+ if (IS_ERR(i2c->regs))
+ return PTR_ERR(i2c->regs);
+
+ /* Try to set the I2C adapter number from dt */
+ bus_nr = of_alias_get_id(np, "i2c");
+
+ /*
+ * Switch to new interface if the SoC also offers the old one.
+ * The control bit is located in the GRF register space.
+ */
+ if (i2c->soc_data->grf_offset >= 0) {
+ struct regmap *grf;
+
+ grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
+ if (IS_ERR(grf)) {
+ dev_err(&pdev->dev,
+ "rk3x-i2c needs 'rockchip,grf' property\n");
+ return PTR_ERR(grf);
+ }
+
+ if (bus_nr < 0) {
+ dev_err(&pdev->dev, "rk3x-i2c needs i2cX alias");
+ return -EINVAL;
+ }
+
+ /* 27+i: write mask, 11+i: value */
+ value = BIT(27 + bus_nr) | BIT(11 + bus_nr);
+
+ ret = regmap_write(grf, i2c->soc_data->grf_offset, value);
+ if (ret != 0) {
+ dev_err(i2c->dev, "Could not write to GRF: %d\n", ret);
+ return ret;
+ }
+ }
+
+ /* IRQ setup */
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "cannot find rk3x IRQ\n");
+ return irq;
+ }
+
+ ret = devm_request_irq(&pdev->dev, irq, rk3x_i2c_irq,
+ 0, dev_name(&pdev->dev), i2c);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "cannot request IRQ\n");
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, i2c);
+
+ ret = clk_prepare(i2c->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Could not prepare clock\n");
+ return ret;
+ }
+
+ ret = i2c_add_adapter(&i2c->adap);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Could not register adapter\n");
+ goto err_clk;
+ }
+
+ dev_info(&pdev->dev, "Initialized RK3xxx I2C bus at 0x%08x\n",
+ (unsigned int)i2c->regs);
+
+ return 0;
+
+err_clk:
+ clk_unprepare(i2c->clk);
+ return ret;
+}
+
+static int rk3x_i2c_remove(struct platform_device *pdev)
+{
+ struct rk3x_i2c *i2c = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&i2c->adap);
+ clk_unprepare(i2c->clk);
+
+ return 0;
+}
+
+static struct platform_driver rk3x_i2c_driver = {
+ .probe = rk3x_i2c_probe,
+ .remove = rk3x_i2c_remove,
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "rk3x-i2c",
+ .of_match_table = rk3x_i2c_match,
+ },
+};
+
+module_platform_driver(rk3x_i2c_driver);
+
+MODULE_DESCRIPTION("Rockchip RK3xxx I2C Bus driver");
+MODULE_AUTHOR("Max Schwarz <[email protected]>");
+MODULE_LICENSE("GPL v2");
--
1.9.1
Hi,
On Sat, Jun 07, 2014 at 07:36:19PM +0200, Max Schwarz wrote:
> Driver for the native I2C adapter found in Rockchip RK3xxx SoCs.
>
> Configuration is only possible through devicetree. The driver is
> interrupt driven and supports the I2C_M_IGNORE_NAK mangling bit.
>
> Signed-off-by: Max Schwarz <[email protected]>
Checking if the spinlock is needed would be nice, but we can also fix
this later. Besides this, my code-checkers say:
CHECKPATCH
CHECK: Logical continuations should be on the previous line
#615: FILE: drivers/i2c/busses/i2c-rk3x.c:470:
+ if (num >= 2 && msgs[0].len < 4
+ && !(msgs[0].flags & I2C_M_RD)
CHECK: Logical continuations should be on the previous line
#616: FILE: drivers/i2c/busses/i2c-rk3x.c:471:
+ && !(msgs[0].flags & I2C_M_RD)
+ && (msgs[1].flags & I2C_M_RD)) {
SPARSE
drivers/i2c/busses/i2c-rk3x.c:173:20: warning: Using plain integer as NULL pointer
drivers/i2c/busses/i2c-rk3x.c:664:45: warning: Using plain integer as NULL pointer
drivers/i2c/busses/i2c-rk3x.c:735:9: warning: cast removes address space of expression
SMATCH
drivers/i2c/busses/i2c-rk3x.c:592 rk3x_i2c_xfer() error: double unlock 'spin_lock:&i2c->lock'
SPATCH
drivers/i2c/busses/i2c-rk3x.c:366:1-10: WARNING: Assignment of bool to 0/1
drivers/i2c/busses/i2c-rk3x.c:187:2-11: WARNING: Assignment of bool to 0/1
CC drivers/i2c/busses/i2c-rk3x.o
drivers/i2c/busses/i2c-rk3x.c: In function 'rk3x_i2c_irq':
drivers/i2c/busses/i2c-rk3x.c:336:15: warning: 'val' may be used uninitialized in this function [-Wuninitialized]
drivers/i2c/busses/i2c-rk3x.c:321:15: note: 'val' was declared here
The smatch warning may be a false positive, please check. The gcc warning is a
false positive but to prevent people from sending fixup patches, please do
something like commit a55b44ac3fe0.
> diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
> new file mode 100644
> index 0000000..7a430f4
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-rk3x.c
> @@ -0,0 +1,769 @@
> +/*
> + * Driver for I2C adapter in Rockchip RK3xxx SoC
> + *
> + * Max Schwarz <[email protected]>
> + * based on the patches by Rockchip Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
No empty line here.
> +#include <linux/i2c.h>
> +#include <linux/time.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/spinlock.h>
> +#include <linux/clk.h>
> +#include <linux/wait.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
Do you really need delay.h and time.h? Look like leftovers to me.
> +/**
> + * Generate a START condition, which triggers a REG_INT_START interrupt.
> + */
> +static void rk3x_i2c_start(struct rk3x_i2c *i2c)
> +{
> + u32 val;
> +
> + dev_dbg(i2c->dev, "start\n");
I think this debug could go now, or?
> +
> + rk3x_i2c_clean_ipd(i2c);
> + i2c_writel(i2c, REG_INT_START, REG_IEN);
> +
> + /* enable adapter with correct mode, send START condition */
> + val = REG_CON_EN | REG_CON_MOD(i2c->mode) | REG_CON_START;
> +
> + /* if we want to react to NACK, set ACTACK bit */
> + if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
> + val |= REG_CON_ACTACK;
> +
> + i2c_writel(i2c, val, REG_CON);
> +}
...
> +
> +static void rk3x_i2c_prepare_read(struct rk3x_i2c *i2c)
> +{
> + unsigned int len = i2c->msg->len - i2c->processed;
> + u32 con;
> +
> + con = i2c_readl(i2c, REG_CON);
> +
> + /*
> + * The hw can read up to 32 bytes at a time. If we need more than one
> + * chunk, send an ACK after the last byte of the current chunk.
> + */
> + if (unlikely(len > 32)) {
> + len = 32;
> + con &= ~REG_CON_LASTACK;
> + } else {
> + con |= REG_CON_LASTACK;
> + }
This is a bit confusing also due to the description of this bit:
"/* 1: do not send ACK after last receive */"
It means not only don't send ACK, but merely do send NACK (to signal end of
read). I though "not send ack" means clock stretching so I was wondering. Maybe
needs some rewording.
> +
> + /* make sure we are in plain RX mode if we read a second chunk */
> + if (i2c->processed != 0) {
> + con &= ~REG_CON_MOD_MASK;
> + con |= REG_CON_MOD(REG_CON_MOD_RX);
> + }
> +
> + i2c_writel(i2c, con, REG_CON);
> + i2c_writel(i2c, len, REG_MRXCNT);
> +}
> +
Thanks, I think we're very close to go...
Wolfram
Hi Wolfram,
thanks for your comments.
On Tuesday 10 June 2014 at 21:27:09, Wolfram Sang wrote:
> Checking if the spinlock is needed would be nice, but we can also fix
> this later.
I'm simply not sure about the spinlock. My knowledge about IRQ handling in
linux is limited.
We have an SMP system here (quadcore), so isn't it possible that the interrupt
handler is still executing on another core when we hit the timeout? Disabling
the interrupt enable bit in the hw would not be enough in that case, because
it does not stop the running interrupt handler. So in my opinion, we need the
spinlock.
For those listening in, here is the code in question:
timeout = wait_event_timeout(i2c->wait, !i2c->busy,
msecs_to_jiffies(WAIT_TIMEOUT));
spin_lock_irqsave(&i2c->lock, flags);
if (timeout == 0) {
dev_err(i2c->dev, "timeout, ipd: 0x%02x, state: %d\n",
i2c_readl(i2c, REG_IPD), i2c->state);
/* Force a STOP condition without interrupt */
i2c_writel(i2c, 0, REG_IEN);
i2c_writel(i2c, REG_CON_EN | REG_CON_STOP, REG_CON);
i2c->state = STATE_IDLE;
...
The irq handler also locks i2c->lock and checks for i2c->state == STATE_IDLE
and does nothing in that case.
> Besides this, my code-checkers say:
>
> CHECKPATCH
> CHECK: Logical continuations should be on the previous line
> #615: FILE: drivers/i2c/busses/i2c-rk3x.c:470:
> + if (num >= 2 && msgs[0].len < 4
> + && !(msgs[0].flags & I2C_M_RD)
>
> CHECK: Logical continuations should be on the previous line
> #616: FILE: drivers/i2c/busses/i2c-rk3x.c:471:
> + && !(msgs[0].flags & I2C_M_RD)
> + && (msgs[1].flags & I2C_M_RD)) {
>
> SPARSE
> drivers/i2c/busses/i2c-rk3x.c:173:20: warning: Using plain integer as NULL
> pointer drivers/i2c/busses/i2c-rk3x.c:664:45: warning: Using plain integer
> as NULL pointer drivers/i2c/busses/i2c-rk3x.c:735:9: warning: cast removes
> address space of expression
> SMATCH
> drivers/i2c/busses/i2c-rk3x.c:592 rk3x_i2c_xfer() error: double unlock
> 'spin_lock:&i2c->lock'
> SPATCH
> drivers/i2c/busses/i2c-rk3x.c:366:1-10: WARNING: Assignment of bool to 0/1
> drivers/i2c/busses/i2c-rk3x.c:187:2-11: WARNING: Assignment of bool to 0/1
> CC drivers/i2c/busses/i2c-rk3x.o
> drivers/i2c/busses/i2c-rk3x.c: In function 'rk3x_i2c_irq':
> drivers/i2c/busses/i2c-rk3x.c:336:15: warning: 'val' may be used
> uninitialized in this function [-Wuninitialized]
> drivers/i2c/busses/i2c-rk3x.c:321:15: note: 'val' was declared here
Thanks for those, fixed. And now I know how to run the checkers ;-)
> The smatch warning may be a false positive, please check.
It is a false positive. After initially locking it, I'm unlocking and locking
the exactly once per loop iteration, so after the loop the lock is locked and
I have to unlock again.
wait_event_timeout is a big macro construct with labels, so probably smatch
gets confused there.
I agree with all your other comments and have modified the code accordingly.
> Thanks, I think we're very close to go...
I'll send a new version shortly, but I'd be really happy if someone could
confirm or refute my thoughts about the lock...
Cheers,
Max