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Date:   Mon, 7 Jun 2021 10:28:49 -0500
From:   Chris Morgan <macroalpha82@gmail.com>
To:     Jon Lin <jon.lin@rock-chips.com>
Cc:     linux-spi@vger.kernel.org, broonie@kernel.org, robh+dt@kernel.org,
        heiko@sntech.de, jbx6244@gmail.com, hjc@rock-chips.com,
        yifeng.zhao@rock-chips.com, sugar.zhang@rock-chips.com,
        linux-rockchip@lists.infradead.org, linux-mtd@lists.infradead.org,
        p.yadav@ti.com, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Chris Morgan <macromorgan@hotmail.com>
Subject: Re: [PATCH v5 2/8] spi: rockchip-sfc: add rockchip serial flash
 controller
Message-ID: <20210607152849.GA43@wintermute.localdomain>
References: <20210607124303.22393-1-jon.lin@rock-chips.com>
 <20210607124303.22393-3-jon.lin@rock-chips.com>
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In-Reply-To: <20210607124303.22393-3-jon.lin@rock-chips.com>
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On Mon, Jun 07, 2021 at 08:42:57PM +0800, Jon Lin wrote:
> From: Chris Morgan <macromorgan@hotmail.com>
> 
> Add the rockchip serial flash controller (SFC) driver.
> 
> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
> Signed-off-by: Jon Lin <jon.lin@rock-chips.com>
> ---

Lukas Wunner provided me some comments on my last patch series
which I am including in here to make sure they get seen.

Thank you.

> 
> Changes in v5: None
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> Changes in v1: None
> 
>  drivers/spi/Kconfig            |   9 +
>  drivers/spi/Makefile           |   1 +
>  drivers/spi/spi-rockchip-sfc.c | 863 +++++++++++++++++++++++++++++++++
>  3 files changed, 873 insertions(+)
>  create mode 100644 drivers/spi/spi-rockchip-sfc.c
> 
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index e71a4c514f7b..d89e5f3c9107 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -658,6 +658,15 @@ config SPI_ROCKCHIP
>  	  The main usecase of this controller is to use spi flash as boot
>  	  device.
>  
> +config SPI_ROCKCHIP_SFC
> +	tristate "Rockchip Serial Flash Controller (SFC)"
> +	depends on ARCH_ROCKCHIP || COMPILE_TEST
> +	depends on HAS_IOMEM && HAS_DMA
> +	help
> +	  This enables support for Rockchip serial flash controller. This
> +	  is a specialized controller used to access SPI flash on some
> +	  Rockchip SOCs.
> +
>  config SPI_RB4XX
>  	tristate "Mikrotik RB4XX SPI master"
>  	depends on SPI_MASTER && ATH79
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 13e54c45e9df..699db95c8441 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -95,6 +95,7 @@ obj-$(CONFIG_SPI_QCOM_GENI)		+= spi-geni-qcom.o
>  obj-$(CONFIG_SPI_QCOM_QSPI)		+= spi-qcom-qspi.o
>  obj-$(CONFIG_SPI_QUP)			+= spi-qup.o
>  obj-$(CONFIG_SPI_ROCKCHIP)		+= spi-rockchip.o
> +obj-$(CONFIG_SPI_ROCKCHIP_SFC)		+= spi-rockchip-sfc.o
>  obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
>  obj-$(CONFIG_MACH_REALTEK_RTL)		+= spi-realtek-rtl.o
>  obj-$(CONFIG_SPI_RPCIF)			+= spi-rpc-if.o
> diff --git a/drivers/spi/spi-rockchip-sfc.c b/drivers/spi/spi-rockchip-sfc.c
> new file mode 100644
> index 000000000000..ddce87a2f319
> --- /dev/null
> +++ b/drivers/spi/spi-rockchip-sfc.c
> @@ -0,0 +1,863 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +//
> +// Rockchip Serial Flash Controller Driver
> +//
> +// Copyright (c) 2017, Rockchip Inc.

Should we change this to you?

> +// Author: Shawn Lin <shawn.lin@rock-chips.com>
> +//
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/iopoll.h>
> +#include <linux/mm.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/interrupt.h>
> +#include <linux/spi/spi-mem.h>
> +
> +/* System control */
> +#define SFC_CTRL			0x0
> +#define  SFC_CTRL_COMMON_BITS_1		0x0
> +#define  SFC_CTRL_COMMON_BITS_2		0x1
> +#define  SFC_CTRL_COMMON_BITS_4		0x2
> +#define  SFC_CTRL_DATA_BITS_SHIFT	12
> +#define  SFC_CTRL_ADDR_BITS_SHIFT	10
> +#define  SFC_CTRL_CMD_BITS_SHIFT	8
> +#define  SFC_CTRL_PHASE_SEL_NEGETIVE	BIT(1)
> +
> +/* Interrupt mask */
> +#define SFC_IMR				0x4
> +#define  SFC_IMR_RX_FULL		BIT(0)
> +#define  SFC_IMR_RX_UFLOW		BIT(1)
> +#define  SFC_IMR_TX_OFLOW		BIT(2)
> +#define  SFC_IMR_TX_EMPTY		BIT(3)
> +#define  SFC_IMR_TRAN_FINISH		BIT(4)
> +#define  SFC_IMR_BUS_ERR		BIT(5)
> +#define  SFC_IMR_NSPI_ERR		BIT(6)
> +#define  SFC_IMR_DMA			BIT(7)
> +
> +/* Interrupt clear */
> +#define SFC_ICLR			0x8
> +#define  SFC_ICLR_RX_FULL		BIT(0)
> +#define  SFC_ICLR_RX_UFLOW		BIT(1)
> +#define  SFC_ICLR_TX_OFLOW		BIT(2)
> +#define  SFC_ICLR_TX_EMPTY		BIT(3)
> +#define  SFC_ICLR_TRAN_FINISH		BIT(4)
> +#define  SFC_ICLR_BUS_ERR		BIT(5)
> +#define  SFC_ICLR_NSPI_ERR		BIT(6)
> +#define  SFC_ICLR_DMA			BIT(7)
> +
> +/* FIFO threshold level */
> +#define SFC_FTLR			0xc
> +#define  SFC_FTLR_TX_SHIFT		0
> +#define  SFC_FTLR_TX_MASK		0x1f
> +#define  SFC_FTLR_RX_SHIFT		8
> +#define  SFC_FTLR_RX_MASK		0x1f
> +
> +/* Reset FSM and FIFO */
> +#define SFC_RCVR			0x10
> +#define  SFC_RCVR_RESET			BIT(0)
> +
> +/* Enhanced mode */
> +#define SFC_AX				0x14
> +
> +/* Address Bit number */
> +#define SFC_ABIT			0x18
> +
> +/* Interrupt status */
> +#define SFC_ISR				0x1c
> +#define  SFC_ISR_RX_FULL_SHIFT		BIT(0)
> +#define  SFC_ISR_RX_UFLOW_SHIFT		BIT(1)
> +#define  SFC_ISR_TX_OFLOW_SHIFT		BIT(2)
> +#define  SFC_ISR_TX_EMPTY_SHIFT		BIT(3)
> +#define  SFC_ISR_TX_FINISH_SHIFT	BIT(4)
> +#define  SFC_ISR_BUS_ERR_SHIFT		BIT(5)
> +#define  SFC_ISR_NSPI_ERR_SHIFT		BIT(6)
> +#define  SFC_ISR_DMA_SHIFT		BIT(7)
> +
> +/* FIFO status */
> +#define SFC_FSR				0x20
> +#define  SFC_FSR_TX_IS_FULL		BIT(0)
> +#define  SFC_FSR_TX_IS_EMPTY		BIT(1)
> +#define  SFC_FSR_RX_IS_EMPTY		BIT(2)
> +#define  SFC_FSR_RX_IS_FULL		BIT(3)
> +#define  SFC_FSR_TXLV_MASK		GENMASK(12, 8)
> +#define  SFC_FSR_TXLV_SHIFT		8
> +#define  SFC_FSR_RXLV_MASK		GENMASK(20, 16)
> +#define  SFC_FSR_RXLV_SHIFT		16
> +
> +/* FSM status */
> +#define SFC_SR				0x24
> +#define  SFC_SR_IS_IDLE			0x0
> +#define  SFC_SR_IS_BUSY			0x1
> +
> +/* Raw interrupt status */
> +#define SFC_RISR			0x28
> +#define  SFC_RISR_RX_FULL		BIT(0)
> +#define  SFC_RISR_RX_UNDERFLOW		BIT(1)
> +#define  SFC_RISR_TX_OVERFLOW		BIT(2)
> +#define  SFC_RISR_TX_EMPTY		BIT(3)
> +#define  SFC_RISR_TRAN_FINISH		BIT(4)
> +#define  SFC_RISR_BUS_ERR		BIT(5)
> +#define  SFC_RISR_NSPI_ERR		BIT(6)
> +#define  SFC_RISR_DMA			BIT(7)
> +
> +/* Master trigger */
> +#define SFC_DMA_TRIGGER			0x80
> +
> +/* Src or Dst addr for master */
> +#define SFC_DMA_ADDR			0x84
> +
> +/* Command */
> +#define SFC_CMD				0x100
> +#define  SFC_CMD_IDX_SHIFT		0
> +#define  SFC_CMD_DUMMY_SHIFT		8
> +#define  SFC_CMD_DIR_RD			0
> +#define  SFC_CMD_DIR_WR			1
> +#define  SFC_CMD_DIR_SHIFT		12
> +#define  SFC_CMD_ADDR_ZERO		(0x0 << 14)
> +#define  SFC_CMD_ADDR_24BITS		(0x1 << 14)
> +#define  SFC_CMD_ADDR_32BITS		(0x2 << 14)
> +#define  SFC_CMD_ADDR_FRS		(0x3 << 14)
> +#define  SFC_CMD_TRAN_BYTES_SHIFT	16
> +#define  SFC_CMD_CS_SHIFT		30
> +
> +/* Address */
> +#define SFC_ADDR			0x104
> +
> +/* Data */
> +#define SFC_DATA			0x108
> +
> +/* The controller and documentation reports that it supports up to 4 CS
> + * devices (0-3), however I have only been able to test a single CS (CS 0)
> + * due to the configuration of my device.
> + */
> +#define SFC_MAX_CHIPSELECT_NUM		4
> +
> +/* The SFC can transfer max 16KB - 1 at one time
> + * we set it to 15.5KB here for alignment.
> + */
> +#define SFC_MAX_TRANS_BYTES		(512 * 31)
> +
> +/* Maximum clock values from datasheet suggest keeping clock value under
> + * 150MHz. No minimum or average value is suggested, but the U-boot BSP driver
> + * has a minimum of 10MHz and a default of 80MHz which seems reasonable.
> + */
> +#define SFC_MIN_SPEED_HZ		(10 * 1000 * 1000)
> +#define SFC_DEFAULT_SPEED_HZ		(80 * 1000 * 1000)
> +#define SFC_MAX_SPEED_HZ		(150 * 1000 * 1000)
> +
> +#define SFC_CMD_DUMMY(x) \
> +	((x) << SFC_CMD_DUMMY_SHIFT)
> +
> +enum rockchip_sfc_iftype {
> +	IF_TYPE_STD,
> +	IF_TYPE_DUAL,
> +	IF_TYPE_QUAD,
> +};
> +
> +struct rockchip_sfc;
> +struct rockchip_sfc_chip_priv {
> +	u8 cs;
> +	u32 clk_rate;
> +	struct rockchip_sfc *sfc;
> +};
> +
> +struct rockchip_sfc {
> +	struct device *dev;
> +	void __iomem *regbase;
> +	struct clk *hclk;
> +	struct clk *clk;
> +	/* virtual mapped addr for dma_buffer */
> +	void *buffer;
> +	dma_addr_t dma_buffer;
> +	struct completion cp;
> +	struct rockchip_sfc_chip_priv flash[SFC_MAX_CHIPSELECT_NUM];
> +	u8 num_chip;
> +	bool use_dma;
> +};
> +
> +static int rockchip_sfc_get_if_type(const struct spi_mem_op *op,
> +				    struct rockchip_sfc *sfc)
> +{
> +	switch (op->data.buswidth) {
> +	case 1:
> +		return IF_TYPE_STD;
> +	case 2:
> +		return IF_TYPE_DUAL;
> +	case 4:
> +		return IF_TYPE_QUAD;
> +	default:
> +		dev_err(sfc->dev, "unsupported SPI read mode\n");
> +		return -EINVAL;
> +	}
> +}
> +
> +static int rockchip_sfc_reset(struct rockchip_sfc *sfc)
> +{
> +	int err;
> +	u32 status;
> +
> +	writel_relaxed(SFC_RCVR_RESET, sfc->regbase + SFC_RCVR);
> +
> +	err = readl_poll_timeout(sfc->regbase + SFC_RCVR, status,
> +				 !(status & SFC_RCVR_RESET), 20,
> +				 jiffies_to_usecs(HZ));
> +	if (err)
> +		dev_err(sfc->dev, "SFC reset never finished\n");
> +
> +	/* Still need to clear the masked interrupt from RISR */
> +	writel_relaxed(SFC_ICLR_RX_FULL | SFC_ICLR_RX_UFLOW |
> +		       SFC_ICLR_TX_OFLOW | SFC_ICLR_TX_EMPTY |
> +		       SFC_ICLR_TRAN_FINISH | SFC_ICLR_BUS_ERR |
> +		       SFC_ICLR_NSPI_ERR | SFC_ICLR_DMA,
> +		       sfc->regbase + SFC_ICLR);
> +
> +	dev_dbg(sfc->dev, "reset\n");
> +
> +	return err;
> +}
> +
> +static int rockchip_sfc_init(struct rockchip_sfc *sfc)
> +{
> +	int err;
> +
> +	err = clk_set_rate(sfc->clk, SFC_DEFAULT_SPEED_HZ);
> +	if (err)
> +		return err;
> +
> +	err = rockchip_sfc_reset(sfc);
> +	if (err)
> +		return err;
> +
> +	/* Mask all eight interrupts */
> +	writel_relaxed(0xff, sfc->regbase + SFC_IMR);
> +
> +	writel_relaxed(SFC_CTRL_PHASE_SEL_NEGETIVE, sfc->regbase + SFC_CTRL);
> +
> +	return 0;
> +}
> +
> +static inline int rockchip_sfc_get_fifo_level(struct rockchip_sfc *sfc, int wr)
> +{
> +	u32 fsr = readl_relaxed(sfc->regbase + SFC_FSR);
> +	int level;
> +
> +	if (wr)
> +		level = (fsr & SFC_FSR_TXLV_MASK) >> SFC_FSR_TXLV_SHIFT;
> +	else
> +		level = (fsr & SFC_FSR_RXLV_MASK) >> SFC_FSR_RXLV_SHIFT;
> +
> +	return level;
> +}
> +
> +static int rockchip_sfc_wait_fifo_ready(struct rockchip_sfc *sfc, int wr, u32 timeout)
> +{
> +	unsigned long deadline = jiffies + timeout;
> +	int level;
> +
> +	while (!(level = rockchip_sfc_get_fifo_level(sfc, wr))) {
> +		if (time_after_eq(jiffies, deadline)) {
> +			dev_warn(sfc->dev, "%s fifo timeout\n", wr ? "write" : "read");
> +			return -ETIMEDOUT;
> +		}
> +		udelay(1);
> +	}
> +
> +	return level;
> +}
> +
> +/* The SFC_CTRL register is a global control register,
> + * when the controller is in busy state(SFC_SR),
> + * SFC_CTRL cannot be set.
> + */
> +static void rockchip_sfc_wait_idle(struct rockchip_sfc *sfc, u32 timeout_us)
> +{
> +	u32 status;
> +	int ret;
> +
> +	ret = readl_poll_timeout(sfc->regbase + SFC_SR, status,
> +				 !(status & SFC_SR_IS_BUSY),
> +				 20, timeout_us);
> +	if (ret) {
> +		dev_err(sfc->dev, "wait sfc idle timeout\n");
> +		rockchip_sfc_reset(sfc);
> +	}
> +}
> +
> +static void rockchip_sfc_setup_ctrl(struct rockchip_sfc *sfc)
> +{
> +	u32 reg;
> +
> +	reg = IF_TYPE_STD << SFC_CTRL_DATA_BITS_SHIFT;
> +	reg |= IF_TYPE_STD << SFC_CTRL_ADDR_BITS_SHIFT;
> +	reg |= IF_TYPE_STD << SFC_CTRL_CMD_BITS_SHIFT;
> +	reg |= SFC_CTRL_PHASE_SEL_NEGETIVE;
> +
> +	rockchip_sfc_wait_idle(sfc, 10000);
> +
> +	writel_relaxed(reg, sfc->regbase + SFC_CTRL);
> +}
> +
> +static int rockchip_sfc_op_reg(struct rockchip_sfc_chip_priv *priv,
> +			       u8 opcode, int len, u8 optype)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	u32 reg;
> +
> +	rockchip_sfc_setup_ctrl(sfc);
> +
> +	reg = opcode << SFC_CMD_IDX_SHIFT;
> +	reg |= len << SFC_CMD_TRAN_BYTES_SHIFT;
> +	reg |= priv->cs << SFC_CMD_CS_SHIFT;
> +	reg |= optype << SFC_CMD_DIR_SHIFT;
> +	writel_relaxed(reg, sfc->regbase + SFC_CMD);
> +
> +	return 0;
> +}
> +
> +static int rockchip_sfc_write_fifo(struct rockchip_sfc *sfc, const u8 *buf, int len)
> +{
> +	u8 bytes = len & 0x3;
> +	u32 dwords;
> +	int tx_level;
> +	u32 write_words;
> +	u32 tmp = 0;
> +
> +	dwords = len >> 2;
> +	while (dwords) {
> +		tx_level = rockchip_sfc_wait_fifo_ready(sfc, SFC_CMD_DIR_WR, HZ);
> +		if (tx_level < 0)
> +			return tx_level;
> +		write_words = min_t(u32, tx_level, dwords);
> +		iowrite32_rep(sfc->regbase + SFC_DATA, buf, write_words);
> +		buf += write_words << 2;
> +		dwords -= write_words;
> +	}
> +
> +	/* write the rest of the bytes that are not a multiple of word size */
> +	if (bytes) {
> +		tx_level = rockchip_sfc_wait_fifo_ready(sfc, SFC_CMD_DIR_WR, HZ);
> +		if (tx_level < 0)
> +			return tx_level;
> +		memcpy(&tmp, buf, bytes);
> +		writel_relaxed(tmp, sfc->regbase + SFC_DATA);
> +	}
> +
> +	return len;
> +}
> +
> +static int rockchip_sfc_read_fifo(struct rockchip_sfc *sfc, u8 *buf, int len)
> +{
> +	u8 bytes = len & 0x3;
> +	u32 dwords;
> +	u8 read_words;
> +	int rx_level;
> +	int tmp;
> +
> +	/* word aligned access only */
> +	dwords = len >> 2;
> +	while (dwords) {
> +		rx_level = rockchip_sfc_wait_fifo_ready(sfc, SFC_CMD_DIR_RD, HZ);
> +		if (rx_level < 0)
> +			return rx_level;
> +		read_words = min_t(u32, rx_level, dwords);
> +		ioread32_rep(sfc->regbase + SFC_DATA, buf, read_words);
> +		buf += read_words << 2;
> +		dwords -= read_words;
> +	}
> +
> +	/* read the rest of the bytes that are not a multiple of word size */
> +	if (bytes) {
> +		rx_level = rockchip_sfc_wait_fifo_ready(sfc, SFC_CMD_DIR_RD, HZ);
> +		if (rx_level < 0)
> +			return rx_level;
> +		tmp = readl_relaxed(sfc->regbase + SFC_DATA);
> +		memcpy(buf, &tmp, bytes);
> +	}
> +
> +	return len;
> +}
> +
> +static int rockchip_sfc_read_reg(struct rockchip_sfc_chip_priv *priv,
> +				 const struct spi_mem_op *op)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	int ret;
> +	int trans;
> +	size_t n_rx = op->data.nbytes;
> +	u8 opcode = op->cmd.opcode;
> +	u8 *rxbuf = op->data.buf.in;
> +
> +	trans = min_t(int, n_rx, SFC_MAX_TRANS_BYTES);
> +	ret = rockchip_sfc_op_reg(priv, opcode, trans, SFC_CMD_DIR_RD);
> +	if (ret)
> +		return ret;
> +
> +	ret = rockchip_sfc_read_fifo(sfc, rxbuf, trans);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int rockchip_sfc_write_reg(struct rockchip_sfc_chip_priv *priv,
> +				  const struct spi_mem_op *op)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	int ret;
> +	size_t n_tx = op->data.nbytes;
> +	u8 opcode = op->cmd.opcode;
> +	const u8 *txbuf = op->data.buf.out;
> +
> +	ret = rockchip_sfc_op_reg(priv, opcode, n_tx, SFC_CMD_DIR_WR);
> +	if (ret)
> +		return ret;
> +	ret = rockchip_sfc_write_fifo(sfc, txbuf, n_tx);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int rockchip_sfc_setup_transfer(struct rockchip_sfc_chip_priv *priv,
> +				       const struct spi_mem_op *op,
> +				       loff_t from_to, size_t len, u8 op_type)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	u8 if_type = IF_TYPE_STD;
> +	u8 addr_width = op->addr.nbytes;
> +	u8 read_dummy_bits = op->dummy.nbytes << 3;
> +	u32 reg;
> +
> +	if (op_type == SFC_CMD_DIR_RD)
> +		if_type = rockchip_sfc_get_if_type(op, sfc);
> +
> +	rockchip_sfc_wait_idle(sfc, 10000);
> +
> +	writel_relaxed((if_type << SFC_CTRL_DATA_BITS_SHIFT) |
> +		       (IF_TYPE_STD << SFC_CTRL_ADDR_BITS_SHIFT) |
> +		       (IF_TYPE_STD << SFC_CTRL_CMD_BITS_SHIFT) |
> +		       SFC_CTRL_PHASE_SEL_NEGETIVE,
> +		       sfc->regbase + SFC_CTRL);
> +
> +	reg = op->cmd.opcode << SFC_CMD_IDX_SHIFT;
> +
> +	reg |= op_type << SFC_CMD_DIR_SHIFT;
> +	reg |= (addr_width == 4) ?
> +		SFC_CMD_ADDR_32BITS : SFC_CMD_ADDR_24BITS;
> +
> +	reg |= priv->cs << SFC_CMD_CS_SHIFT;
> +	reg |= len << SFC_CMD_TRAN_BYTES_SHIFT;
> +
> +	if (op_type == SFC_CMD_DIR_RD)
> +		reg |= SFC_CMD_DUMMY(read_dummy_bits);
> +
> +	writel_relaxed(reg, sfc->regbase + SFC_CMD);
> +	writel_relaxed(from_to, sfc->regbase + SFC_ADDR);
> +
> +	return 0;
> +}
> +
> +static int rockchip_sfc_do_dma_transfer(struct rockchip_sfc_chip_priv *priv,
> +					const struct spi_mem_op *op, loff_t from_to,
> +					dma_addr_t dma_buf, size_t len, u8 op_type)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	u32 reg;
> +	int err = 0;
> +
> +	init_completion(&sfc->cp);
> +
> +	writel_relaxed(SFC_ICLR_RX_FULL | SFC_ICLR_RX_UFLOW |
> +		       SFC_ICLR_TX_OFLOW | SFC_ICLR_TX_EMPTY |
> +		       SFC_ICLR_TRAN_FINISH | SFC_ICLR_BUS_ERR |
> +		       SFC_ICLR_NSPI_ERR | SFC_ICLR_DMA,
> +		       sfc->regbase + SFC_ICLR);
> +
> +	/* Enable transfer complete interrupt */
> +	reg = readl_relaxed(sfc->regbase + SFC_IMR);
> +	reg &= ~SFC_IMR_TRAN_FINISH;
> +	writel_relaxed(reg, sfc->regbase + SFC_IMR);
> +
> +	err = rockchip_sfc_setup_transfer(priv, op, from_to, len, op_type);
> +	if (err < 0)
> +		return err;
> +
> +	writel_relaxed(dma_buf, sfc->regbase + SFC_DMA_ADDR);
> +
> +	/*
> +	 * Start dma but note that the sfc->dma_buffer is derived from
> +	 * dmam_alloc_coherent so we don't actually need any sync operations
> +	 * for coherent dma memory.
> +	 */
> +	writel(0x1, sfc->regbase + SFC_DMA_TRIGGER);
> +
> +	/* Wait for the interrupt. */
> +	if (!wait_for_completion_timeout(&sfc->cp, msecs_to_jiffies(2000))) {
> +		dev_err(sfc->dev, "DMA wait for transfer finish timeout\n");
> +		err = -ETIMEDOUT;
> +	}
> +
> +	writel_relaxed(SFC_ICLR_RX_FULL | SFC_ICLR_RX_UFLOW |
> +		       SFC_ICLR_TX_OFLOW | SFC_ICLR_TX_EMPTY |
> +		       SFC_ICLR_TRAN_FINISH | SFC_ICLR_BUS_ERR |
> +		       SFC_ICLR_NSPI_ERR | SFC_ICLR_DMA,
> +		       sfc->regbase + SFC_ICLR);
> +	/* Disable transfer finish interrupt */
> +	reg = readl_relaxed(sfc->regbase + SFC_IMR);
> +	reg |= SFC_IMR_TRAN_FINISH;
> +	writel_relaxed(reg, sfc->regbase + SFC_IMR);
> +
> +	if (err) {
> +		rockchip_sfc_reset(sfc);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static inline int rockchip_sfc_pio_write(struct rockchip_sfc *sfc, u_char *buf,
> +					 size_t len)
> +{
> +	return rockchip_sfc_write_fifo(sfc, buf, len);
> +}
> +
> +static inline int rockchip_sfc_pio_read(struct rockchip_sfc *sfc, u_char *buf,
> +					size_t len)
> +{
> +	return rockchip_sfc_read_fifo(sfc, buf, len);
> +}
> +
> +static int rockchip_sfc_pio_transfer(struct rockchip_sfc_chip_priv *priv,
> +				     const struct spi_mem_op *op, loff_t from_to, size_t len,
> +				     u_char *buf, u8 op_type)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	size_t trans;
> +	int ret;
> +
> +	trans = min_t(size_t, SFC_MAX_TRANS_BYTES, len);
> +	ret = rockchip_sfc_setup_transfer(priv, op, from_to, trans, op_type);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (op_type == SFC_CMD_DIR_WR)
> +		ret = rockchip_sfc_pio_write(sfc, buf, trans);
> +	else
> +		ret = rockchip_sfc_pio_read(sfc, buf, trans);
> +
> +	return ret;
> +}
> +
> +static int rockchip_sfc_dma_transfer(struct rockchip_sfc_chip_priv *priv,
> +				     const struct spi_mem_op *op, loff_t from_to, size_t len,
> +				     u_char *buf, u8 op_type)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +	size_t trans;
> +	int ret;
> +
> +	trans = min_t(size_t, SFC_MAX_TRANS_BYTES, len);
> +
> +	if (op_type == SFC_CMD_DIR_WR)
> +		memcpy(sfc->buffer, buf, trans);
> +
> +	ret = rockchip_sfc_do_dma_transfer(priv, op, from_to, sfc->dma_buffer,
> +					   trans, op_type);
> +	if (ret) {
> +		dev_warn(sfc->dev, "DMA timeout\n");
> +		return ret;
> +	}
> +
> +	if (op_type == SFC_CMD_DIR_RD)
> +		memcpy(buf, sfc->buffer, trans);
> +
> +	return trans;
> +}
> +
> +static ssize_t rockchip_sfc_do_rd_wr(struct rockchip_sfc_chip_priv *priv,
> +				     const struct spi_mem_op *op, loff_t from_to, size_t len,
> +				     u_char *buf, u32 op_type)
> +{
> +	struct rockchip_sfc *sfc = priv->sfc;
> +
> +	/* DMA can only handle word aligned transfer chunks */
> +	if (likely(sfc->use_dma) && !(len & 0x3))
> +		return rockchip_sfc_dma_transfer(priv, op, from_to, len, buf, op_type);
> +	else
> +		return rockchip_sfc_pio_transfer(priv, op, from_to, len, buf, op_type);
> +}
> +
> +static ssize_t rockchip_sfc_read(struct rockchip_sfc_chip_priv *priv,
> +				 const struct spi_mem_op *op)
> +{
> +	loff_t from = op->addr.val;
> +	size_t len = op->data.nbytes;
> +	u_char *read_buf = op->data.buf.in;
> +
> +	return rockchip_sfc_do_rd_wr(priv, op, from, len, read_buf, SFC_CMD_DIR_RD);
> +}
> +
> +static ssize_t rockchip_sfc_write(struct rockchip_sfc_chip_priv *priv,
> +				  const struct spi_mem_op *op)
> +{
> +	loff_t to = op->addr.val;
> +	size_t len = op->data.nbytes;
> +	const u_char *write_buf = op->data.buf.out;
> +
> +	return rockchip_sfc_do_rd_wr(priv, op, to, len, (u_char *)write_buf, SFC_CMD_DIR_WR);
> +}
> +
> +static int rockchip_sfc_mem_process(struct spi_mem *mem, const struct spi_mem_op *op)
> +{
> +	struct rockchip_sfc *sfc = spi_master_get_devdata(mem->spi->master);
> +	struct rockchip_sfc_chip_priv *priv = &sfc->flash[mem->spi->chip_select];
> +
> +	if (op->data.dir == SPI_MEM_DATA_IN && op->data.buf.in) {
> +		if (!op->addr.nbytes)
> +			return rockchip_sfc_read_reg(priv, op);
> +
> +		return rockchip_sfc_read(priv, op);
> +	}
> +
> +	if (!op->addr.nbytes || !op->data.buf.out)
> +		return rockchip_sfc_write_reg(priv, op);
> +
> +	return rockchip_sfc_write(priv, op);
> +}
> +
> +static int rockchip_sfc_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
> +{
> +	struct rockchip_sfc *sfc = spi_master_get_devdata(mem->spi->master);
> +	struct rockchip_sfc_chip_priv *priv = &sfc->flash[mem->spi->chip_select];
> +	int ret;
> +
> +	ret = clk_set_rate(sfc->clk, priv->clk_rate);
> +	if (ret)
> +		return ret;
> +
> +	ret = rockchip_sfc_mem_process(mem, op);
> +	if (ret < 0) {
> +		dev_err(&mem->spi->dev, "operation failed with %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const char *rockchip_sfc_get_name(struct spi_mem *mem)
> +{
> +	struct rockchip_sfc *sfc = spi_master_get_devdata(mem->spi->master);
> +	struct device *dev = sfc->dev;
> +
> +	return devm_kasprintf(dev, GFP_KERNEL, "%s.%d", dev_name(dev), mem->spi->chip_select);
> +}
> +
> +static const struct spi_controller_mem_ops rockchip_sfc_mem_ops = {
> +	.exec_op = rockchip_sfc_exec_mem_op,
> +	.get_name = rockchip_sfc_get_name,
> +};
> +
> +static int rockchip_sfc_register(struct device_node *np,
> +				 struct rockchip_sfc *sfc)
> +{
> +	struct device *dev = sfc->dev;
> +	int ret;
> +
> +	ret = of_property_read_u8(np, "reg", &sfc->flash[sfc->num_chip].cs);
> +	if (ret) {
> +		dev_err(dev, "No reg property for %s\n",
> +			np->full_name);
> +		return ret;
> +	}
> +
> +	ret = of_property_read_u32(np, "spi-max-frequency",
> +				   &sfc->flash[sfc->num_chip].clk_rate);
> +	if (ret) {
> +		dev_err(dev, "No spi-max-frequency property for %s\n",
> +			np->full_name);
> +		return ret;
> +	}
> +
> +	sfc->flash[sfc->num_chip].sfc = sfc;
> +	sfc->num_chip++;
> +	return 0;
> +}
> +
> +static int rockchip_sfc_register_all(struct rockchip_sfc *sfc)
> +{
> +	struct device *dev = sfc->dev;
> +	struct device_node *np;
> +	int ret;
> +
> +	for_each_available_child_of_node(dev->of_node, np) {
> +		ret = rockchip_sfc_register(np, sfc);
> +		if (ret)
> +			dev_err(dev, "Failed to register all chips\n");
> +			return ret;
> +
> +		if (sfc->num_chip >= SFC_MAX_CHIPSELECT_NUM) {
> +			dev_warn(dev, "Exceeds the max cs limitation\n");
> +			break;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static irqreturn_t rockchip_sfc_irq_handler(int irq, void *dev_id)
> +{
> +	struct rockchip_sfc *sfc = dev_id;
> +	u32 reg;
> +
> +	reg = readl(sfc->regbase + SFC_RISR);
> +
> +	/* Clear interrupt if transfer is finished */
> +	if (reg & SFC_RISR_TRAN_FINISH) {
> +		writel_relaxed(reg, sfc->regbase + SFC_ICLR);
> +		complete(&sfc->cp);
> +		return IRQ_HANDLED;
> +	}
> +
> +	return IRQ_NONE;
> +}
> +
> +static int rockchip_sfc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct spi_master *master;
> +	struct resource *res;
> +	struct rockchip_sfc *sfc;
> +	int ret;
> +
> +	master = spi_alloc_master(&pdev->dev, sizeof(*sfc));

We should use devm_spi_alloc_master here since we're not freeing
the allocation if we fail.

> +	if (!master) {

We should just return here (no dev_err) since an error will stackdump.

> +		dev_err(&pdev->dev, "spi_alloc_master failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	master->mem_ops = &rockchip_sfc_mem_ops;
> +	master->dev.of_node = pdev->dev.of_node;
> +	master->mode_bits = SPI_RX_QUAD | SPI_RX_DUAL;
> +	master->min_speed_hz = SFC_MIN_SPEED_HZ;
> +	master->max_speed_hz = SFC_MAX_SPEED_HZ;
> +
> +	sfc = spi_master_get_devdata(master);
> +	sfc->dev = dev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	sfc->regbase = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(sfc->regbase))
> +		return PTR_ERR(sfc->regbase);
> +
> +	sfc->clk = devm_clk_get(&pdev->dev, "sfc");
> +	if (IS_ERR(sfc->clk)) {
> +		dev_err(&pdev->dev, "Failed to get sfc interface clk\n");
> +		return PTR_ERR(sfc->clk);
> +	}
> +
> +	sfc->hclk = devm_clk_get(&pdev->dev, "ahb");
> +	if (IS_ERR(sfc->hclk)) {
> +		dev_err(&pdev->dev, "Failed to get sfc ahb clk\n");
> +		return PTR_ERR(sfc->hclk);
> +	}
> +
> +	sfc->use_dma = !of_property_read_bool(sfc->dev->of_node,
> +					      "rockchip,sfc-no-dma");
> +
> +	if (sfc->use_dma) {
> +		ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
> +		if (ret) {
> +			dev_warn(dev, "Unable to set dma mask\n");
> +			return ret;
> +		}
> +
> +		sfc->buffer = dmam_alloc_coherent(dev, SFC_MAX_TRANS_BYTES,
> +						  &sfc->dma_buffer,
> +						  GFP_KERNEL);
> +		if (!sfc->buffer)
> +			return -ENOMEM;
> +	}
> +
> +	ret = clk_prepare_enable(sfc->hclk);
> +	if (ret) {

We don't need to print an error and goto anything, we should just return
a failure at this point. No need for the err_hclk label either.

> +		dev_err(&pdev->dev, "Failed to enable ahb clk\n");
> +		goto err_hclk;
> +	}
> +
> +	ret = clk_prepare_enable(sfc->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to enable interface clk\n");
> +		goto err_clk;
> +	}
> +
> +	/* Find the irq */
> +	ret = platform_get_irq(pdev, 0);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to get the irq\n");
> +		goto err_irq;
> +	}
> +
> +	ret = devm_request_irq(dev, ret, rockchip_sfc_irq_handler,
> +			       0, pdev->name, sfc);
> +	if (ret) {
> +		dev_err(dev, "Failed to request irq\n");
> +		goto err_irq;
> +	}
> +
> +	sfc->num_chip = 0;
> +	ret = rockchip_sfc_init(sfc);
> +	if (ret)
> +		goto err_irq;
> +
> +	ret = rockchip_sfc_register_all(sfc);
> +	if (ret)
> +		goto err_irq;
> +

We should use spi_register_master, not devm_spi_register_master here.

> +	ret = devm_spi_register_master(dev, master);
> +	if (ret)
> +		goto err_irq;
> +
> +	return 0;
> +
> +err_irq:
> +	clk_disable_unprepare(sfc->clk);
> +err_clk:
> +	clk_disable_unprepare(sfc->hclk);
> +err_hclk:
> +	return ret;
> +}
> +
> +static int rockchip_sfc_remove(struct platform_device *pdev)
> +{
> +	struct rockchip_sfc *sfc = platform_get_drvdata(pdev);
> +

We need to add an spi_unregister_master here.

The comments for these changes from Lukas are as follows:

You need to use spi_register_master() here (*not* the devm variant)
and add spi_unregister_master() at the top of rockchip_sfc_remove().

The reason is that ->remove() is executed *before* devres resources
are freed and rockchip_sfc_remove() disables the clocks, presumably
rendering the chip inaccessible.

However the chip may be performing SPI transfers until
spi_unregister_master() returns, so the chip needs to be accessible
as long.

Because you're using devm_spi_register_master(), the chip may try
to perform SPI transfers even though its clocks have been disabled.
So you've got an ordering problem with the devm variant.

> +	clk_disable_unprepare(sfc->clk);
> +	clk_disable_unprepare(sfc->hclk);
> +	return 0;
> +}
> +
> +static const struct of_device_id rockchip_sfc_dt_ids[] = {
> +	{ .compatible = "rockchip,rk3036-sfc"},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, rockchip_sfc_dt_ids);
> +
> +static struct platform_driver rockchip_sfc_driver = {
> +	.driver = {
> +		.name	= "rockchip-sfc",
> +		.of_match_table = rockchip_sfc_dt_ids,
> +	},
> +	.probe	= rockchip_sfc_probe,
> +	.remove	= rockchip_sfc_remove,
> +};
> +module_platform_driver(rockchip_sfc_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Rockchip Serial Flash Controller Driver");

Should we change this to you?  Thanks.

> +MODULE_AUTHOR("Shawn Lin <shawn.lin@rock-chips.com>");
> -- 
> 2.17.1
> 
> 
>