Message-ID: <20210609023619.GA1191@wintermute.localdomain>
Date:   Tue, 8 Jun 2021 21:36:19 -0500
From:   Chris Morgan <macroalpha82@...il.com>
To:     Jon Lin <jon.lin@...k-chips.com>
Cc:     linux-spi@...r.kernel.org, broonie@...nel.org, robh+dt@...nel.org,
        heiko@...ech.de, jbx6244@...il.com, hjc@...k-chips.com,
        yifeng.zhao@...k-chips.com, sugar.zhang@...k-chips.com,
        linux-rockchip@...ts.infradead.org, linux-mtd@...ts.infradead.org,
        p.yadav@...com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Chris Morgan <macromorgan@...mail.com>
Subject: Re: [PATCH v6 2/8] spi: rockchip-sfc: add rockchip serial flash
 controller

On Tue, Jun 08, 2021 at 10:26:38AM +0800, Jon Lin wrote:
> From: Chris Morgan <macromorgan@...mail.com>
> 
> Add the rockchip serial flash controller (SFC) driver.
> 
> Signed-off-by: Chris Morgan <macromorgan@...mail.com>
> Signed-off-by: Jon Lin <jon.lin@...k-chips.com>

I think I hit "reply" earlier when I meant to hit "reply-all". Whoops.

I wanted to say that for now this driver is not working for me on the
v3 hardware. There appears to be something wrong with alternating
between page programs and erase. I can consistently reproduce this by
writing a 4MB image of random data to my SPI flash chip at offset
c00000 using dd to mtdblock0. I've dumped the contents of what is
written to the controller and it appears at some point it goes from
doing a page program (02) to a dual io read (bb) to a sector erase
(20), then it repeatedly reads the status register (05) and I assume
the register never changes. As a result it just keeps looping over
the status register then eventually times out. I'm still debugging
to try and figure out exactly what is going on though.

I also noticed that reading does not work consistently using dd
from the mtd0 device, however I have a proposed fix for that which
I list below at the appropriate section.

> ---
> 
> Changes in v6: None
> 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 | 660 +++++++++++++++++++++++++++++++++
>  3 files changed, 670 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..ec25ad278096
> --- /dev/null
> +++ b/drivers/spi/spi-rockchip-sfc.c
> @@ -0,0 +1,660 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Rockchip Serial Flash Controller Driver
> + *
> + * Copyright (c) 2017-2021, Rockchip Inc.
> + * Author: Shawn Lin <shawn.lin@...k-chips.com>
> + *	   Chris Morgan <macroalpha82@...il.com>
> + *	   Jon Lin <Jon.lin@...k-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_PHASE_SEL_NEGETIVE	BIT(1)
> +#define  SFC_CTRL_CMD_BITS_SHIFT	8
> +#define  SFC_CTRL_ADDR_BITS_SHIFT	10
> +#define  SFC_CTRL_DATA_BITS_SHIFT	12
> +
> +/* 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)
> +
> +/* Version */
> +#define SFC_VER				0x2C
> +#define  SFC_VER_3			0x3
> +#define  SFC_VER_4			0x4
> +#define  SFC_VER_5			0x5
> +
> +/* Master trigger */
> +#define SFC_DMA_TRIGGER			0x80
> +
> +/* Src or Dst addr for master */
> +#define SFC_DMA_ADDR			0x84
> +
> +/* Length control register extension 32GB */
> +#define SFC_LEN_CTRL			0x88
> +#define SFC_LEN_CTRL_TRB_SEL		1
> +#define SFC_LEN_EXT			0x8C
> +
> +/* Command */
> +#define SFC_CMD				0x100
> +#define  SFC_CMD_IDX_SHIFT		0
> +#define  SFC_CMD_DUMMY_SHIFT		8
> +#define  SFC_CMD_DIR_SHIFT		12
> +#define  SFC_CMD_DIR_RD			0
> +#define  SFC_CMD_DIR_WR			1
> +#define  SFC_CMD_ADDR_SHIFT		14
> +#define  SFC_CMD_ADDR_0BITS		0
> +#define  SFC_CMD_ADDR_24BITS		1
> +#define  SFC_CMD_ADDR_32BITS		2
> +#define  SFC_CMD_ADDR_XBITS		3
> +#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_IOSIZE_VER3		(512 * 31)
> +
> +#define SFC_MAX_IOSIZE_VER4		(0xFFFFFFFF)
> +
> +/* DMA is only enabled for large data transmission */
> +#define SFC_DMA_TRANS_THRETHOLD		(0x40)
> +
> +/* 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)
> +
> +struct rockchip_sfc {
> +	struct device *dev;
> +	void __iomem *regbase;
> +	struct clk *hclk;
> +	struct clk *clk;
> +	u32 frequency;
> +	/* virtual mapped addr for dma_buffer */
> +	void *buffer;
> +	dma_addr_t dma_buffer;
> +	struct completion cp;
> +	bool use_dma;
> +	u32 max_iosize;
> +};
> +
> +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(0xFFFFFFFF, sfc->regbase + SFC_ICLR);
> +
> +	dev_dbg(sfc->dev, "reset\n");
> +
> +	return err;
> +}
> +
> +static u16 rockchip_sfc_get_version(struct rockchip_sfc *sfc)
> +{
> +	return  (u16)(readl(sfc->regbase + SFC_VER) & 0xffff);
> +}
> +
> +static u32 rockchip_sfc_get_max_iosize(struct rockchip_sfc *sfc)
> +{
> +	if (rockchip_sfc_get_version(sfc) >= SFC_VER_4)
> +		return SFC_MAX_IOSIZE_VER4;
> +	else
> +		return SFC_MAX_IOSIZE_VER3;
> +}
> +
> +static int rockchip_sfc_init(struct rockchip_sfc *sfc)
> +{
> +	writel(0, sfc->regbase + SFC_CTRL);
> +	if (rockchip_sfc_get_version(sfc) >= SFC_VER_4)
> +		writel(SFC_LEN_CTRL_TRB_SEL, sfc->regbase + SFC_LEN_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;
> +}
> +
> +static int rockchip_sfc_xfer_setup(struct rockchip_sfc *sfc,
> +				   struct spi_mem *mem,
> +				   const struct spi_mem_op *op,
> +				   u32 len)
> +{
> +	u32 ctrl = 0, cmd = 0;
> +
> +	/* set CMD */
> +	cmd = op->cmd.opcode;
> +	ctrl |= ((op->cmd.buswidth >> 1) << SFC_CTRL_CMD_BITS_SHIFT);
> +
> +	/* set ADDR */
> +	if (op->addr.nbytes) {
> +		if (op->addr.nbytes == 4) {
> +			cmd |= SFC_CMD_ADDR_32BITS << SFC_CMD_ADDR_SHIFT;
> +		} else if (op->addr.nbytes == 3) {
> +			cmd |= SFC_CMD_ADDR_24BITS << SFC_CMD_ADDR_SHIFT;
> +		} else {
> +			cmd |= SFC_CMD_ADDR_XBITS << SFC_CMD_ADDR_SHIFT;
> +			writel_relaxed(op->addr.nbytes * 8 - 1, sfc->regbase + SFC_ABIT);
> +		}
> +
> +		ctrl |= ((op->addr.buswidth >> 1) << SFC_CTRL_ADDR_BITS_SHIFT);
> +	}
> +
> +	/* set DUMMY */
> +	if (op->dummy.nbytes) {
> +		if (op->dummy.buswidth == 4)
> +			cmd |= op->dummy.nbytes * 2 << SFC_CMD_DUMMY_SHIFT;
> +		else if (op->dummy.buswidth == 2)
> +			cmd |= op->dummy.nbytes * 4 << SFC_CMD_DUMMY_SHIFT;
> +		else
> +			cmd |= op->dummy.nbytes * 8 << SFC_CMD_DUMMY_SHIFT;
> +	}
> +

I have no experience optimizing code or anything, but would it help
here to read the output of rockchip_sfc_get_version() to a variable
in the driver data, and then check that each time we hit this?
I don't know if there is any real-world difference in reading a
variable versus reading a register, so I'm just asking. It's not like
the sfc_version will change once the device is probed. :-)

> +	/* set DATA */
> +	if (rockchip_sfc_get_version(sfc) >= SFC_VER_4) /* Clear it if no data to transfer */
> +		writel(len, sfc->regbase + SFC_LEN_EXT);
> +	else
> +		cmd |= len << SFC_CMD_TRAN_BYTES_SHIFT;
> +	if (len) {
> +		if (op->data.dir == SPI_MEM_DATA_OUT)
> +			cmd |= SFC_CMD_DIR_WR << SFC_CMD_DIR_SHIFT;
> +
> +		ctrl |= ((op->data.buswidth >> 1) << SFC_CTRL_DATA_BITS_SHIFT);
> +	}
> +	if (!len && op->addr.nbytes)
> +		cmd |= SFC_CMD_DIR_WR << SFC_CMD_DIR_SHIFT;
> +
> +	/* set the Controller */
> +	ctrl |= SFC_CTRL_PHASE_SEL_NEGETIVE;
> +	cmd |= mem->spi->chip_select << SFC_CMD_CS_SHIFT;
> +
> +	dev_dbg(sfc->dev, "addr.nbytes=%x(x%d) dummy.nbytes=%x(x%d)\n",
> +		op->addr.nbytes, op->addr.buswidth,
> +		op->dummy.nbytes, op->dummy.buswidth);
> +	dev_dbg(sfc->dev, "ctrl=%x cmd=%x addr=%llx len=%x\n",
> +		ctrl, cmd, op->addr.val, len);
> +
> +	writel(ctrl, sfc->regbase + SFC_CTRL);
> +	writel(cmd, sfc->regbase + SFC_CMD);
> +	if (op->addr.nbytes)
> +		writel(op->addr.val, sfc->regbase + SFC_ADDR);
> +
> +	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 non word aligned bytes */
> +	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(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 non word aligned bytes */
> +	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_fifo_transfer_dma(struct rockchip_sfc *sfc, dma_addr_t dma_buf, size_t len)
> +{
> +	u32 reg;
> +	int err = 0;
> +
> +	init_completion(&sfc->cp);
> +
> +	writel(0xFFFFFFFF, sfc->regbase + SFC_ICLR);
> +
> +	/* Enable transfer complete interrupt */
> +	reg = readl(sfc->regbase + SFC_IMR);
> +	reg &= ~SFC_IMR_DMA;
> +	writel(reg, sfc->regbase + SFC_IMR);
> +	writel((u32)dma_buf, sfc->regbase + SFC_DMA_ADDR);
> +	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(0xFFFFFFFF, sfc->regbase + SFC_ICLR);
> +	/* Disable transfer finish interrupt */
> +	reg = readl(sfc->regbase + SFC_IMR);
> +	reg |= SFC_IMR_DMA;
> +	writel(reg, sfc->regbase + SFC_IMR);
> +
> +	return len;
> +}
> +
> +static int rockchip_sfc_xfer_data_poll(struct rockchip_sfc *sfc,
> +				       const struct spi_mem_op *op, u32 len)
> +{
> +	dev_dbg(sfc->dev, "xfer_poll len=%x\n", len);
> +
> +	if (op->data.dir == SPI_MEM_DATA_OUT)
> +		return rockchip_sfc_write_fifo(sfc, op->data.buf.out, len);
> +	else
> +		return rockchip_sfc_read_fifo(sfc, op->data.buf.in, len);
> +}
> +
> +static int rockchip_sfc_xfer_data_dma(struct rockchip_sfc *sfc,
> +				      const struct spi_mem_op *op, u32 len)
> +{
> +	int ret;
> +
> +	dev_dbg(sfc->dev, "xfer_dma len=%x\n", len);
> +
> +	if (op->data.dir == SPI_MEM_DATA_OUT) {
> +		memcpy_toio(sfc->buffer, op->data.buf.out, len);
> +		ret = rockchip_sfc_fifo_transfer_dma(sfc, sfc->dma_buffer, len);
> +	} else {
> +		ret = rockchip_sfc_fifo_transfer_dma(sfc, sfc->dma_buffer, len);
> +		memcpy_fromio(op->data.buf.in, sfc->buffer, len);
> +	}
> +
> +	return ret;
> +}
> +
> +static int rockchip_sfc_xfer_done(struct rockchip_sfc *sfc, u32 timeout_us)
> +{
> +	int ret = 0;
> +	u32 status;
> +
> +	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);
> +
> +		ret = -EIO;
> +	}
> +
> +	return ret;
> +}
> +
> +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);
> +	u32 len = min_t(u32, op->data.nbytes, sfc->max_iosize);

Is it necessary to use the minimum of these 2 values if we use an
adjust_op_size which I propose below?

> +	int ret;
> +

Again I'm asking this as someone with no experience optimizing code
or with compilers, but would it help to add an unlikely() here? It's
all but guaranteed the first time this code path is called the clock
will need to be set, but each subsequent call should not really have
to care since the clock likely won't be changing (as long as we're on
the same CS). We can also then set the sfc->frequency to what the
max_speed_hz was after successfully setting the rate so we can hit the
faster path after the first run (it looks like it's checking the
uninitalized value but never updating it after it's changed, so it's
always doing the clk_set_rate()).

Also, should we clamp the clock speed between the min and max values?

> +	if (mem->spi->max_speed_hz != sfc->frequency) {
> +		if (clk_set_rate(sfc->clk, mem->spi->max_speed_hz))
> +			return ret;
> +		dev_dbg(sfc->dev, "set_freq=%dHz real_freq=%ldHz\n",
> +			sfc->frequency, clk_get_rate(sfc->clk));
> +	}
> +
> +	rockchip_sfc_xfer_setup(sfc, mem, op, len);
> +	if (len) {
> +		if (likely(sfc->use_dma) && !(len & 0x3) && len >= SFC_DMA_TRANS_THRETHOLD)
> +			ret = rockchip_sfc_xfer_data_dma(sfc, op, len);
> +		else
> +			ret = rockchip_sfc_xfer_data_poll(sfc, op, len);
> +
> +		if (ret != len) {
> +			dev_err(sfc->dev, "xfer data failed ret %d dir %d\n", ret, op->data.dir);
> +
> +			return -EIO;
> +		}
> +	}
> +
> +	return rockchip_sfc_xfer_done(sfc, 100000);
> +}
> +

I'll be honest with you, I had no idea if I needed this function or
not (the rockchip_sfc_get_name() function). I'm pretty sure it's not
needed though, so I assume it can be safely removed.

> +static const char *rockchip_sfc_get_name(struct spi_mem *mem)
> +{
> +	return devm_kasprintf(&mem->spi->dev, GFP_KERNEL, "%s.%d",
> +			      dev_name(&mem->spi->dev), mem->spi->chip_select);
> +}
> +

I had an issue with doing dd as mentioned above reading against mtd0,
and was able to fix it by adding a mem_op of adjust_op_size like this.
Not sure if it works for the v4/v5 hardware though.

static int rockchip_sfc_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
{
	struct rockchip_sfc *sfc = spi_master_get_devdata(mem->spi->master);

	op->data.nbytes = min(op->data.nbytes, sfc->max_iosize);
	return 0;
}

> +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 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 */
> +	writel_relaxed(reg, sfc->regbase + SFC_ICLR);
> +
> +	if (reg & SFC_RISR_DMA)
> +		complete(&sfc->cp);
> +

>From a previous comment, we should only clear the interrupt if we
handle the specific one in question.

> +	return IRQ_HANDLED;
> +}
> +
> +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 = devm_spi_alloc_master(&pdev->dev, sizeof(*sfc));
> +	if (!master)
> +		return -ENOMEM;
> +
> +	master->mem_ops = &rockchip_sfc_mem_ops;
> +	master->dev.of_node = pdev->dev.of_node;
> +	master->mode_bits = SPI_TX_QUAD | SPI_TX_DUAL | SPI_RX_QUAD | SPI_RX_DUAL;
> +	master->min_speed_hz = SFC_MIN_SPEED_HZ;
> +	master->max_speed_hz = SFC_MAX_SPEED_HZ;
> +	master->num_chipselect = SFC_MAX_CHIPSELECT_NUM;
> +
> +	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, "clk_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, "hclk_sfc");
> +	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_IOSIZE_VER3,
> +						  &sfc->dma_buffer,
> +						  GFP_KERNEL);
> +		if (!sfc->buffer)
> +			return -ENOMEM;
> +	}
> +
> +	ret = clk_prepare_enable(sfc->hclk);
> +	if (ret) {
> +		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");
> +
> +		return ret;
> +	}
> +
> +	ret = rockchip_sfc_init(sfc);
> +	if (ret)
> +		goto err_irq;
> +
> +	sfc->max_iosize = rockchip_sfc_get_max_iosize(sfc);
> +
> +	ret = spi_register_master(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 spi_master *master = platform_get_drvdata(pdev);
> +	struct rockchip_sfc *sfc = platform_get_drvdata(pdev);
> +
> +	spi_unregister_master(master);
> +
> +	clk_disable_unprepare(sfc->clk);
> +	clk_disable_unprepare(sfc->hclk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id rockchip_sfc_dt_ids[] = {
> +	{ .compatible = "rockchip,px30-sfc"},
> +	{ .compatible = "rockchip,rk3036-sfc"},
> +	{ .compatible = "rockchip,rk3308-sfc"},
> +	{ .compatible = "rockchip,rv1126-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");
> +MODULE_AUTHOR("Shawn Lin <shawn.lin@...k-chips.com>");
> +MODULE_AUTHOR("Chris Morgan <macroalpha82@...il.com>");

I know folks will hate on me for this (and for good reason given it
messes up IDs and stuff), but I prefer macromorgan@...mail.com if my
email is in here, as that's the one I've been using for decades...

> +MODULE_AUTHOR("Jon Lin <Jon.lin@...k-chips.com>");
> -- 
> 2.17.1
> 
> 
> 

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