Subject: [PATCH v4 2/3] mtd: mtk-nor: mtk serial flash controller driver

From: [email-masked] (Brian Norris)
Date: Fri, 16 Oct 2015 00:39:59 -0700

Hi Bayi,

On Tue, Oct 13, 2015 at 05:39:19PM +0800, Bayi Cheng wrote:
> add spi nor flash driver for mediatek controller
> 
> Signed-off-by: Bayi Cheng <[email-masked]>
> ---
>  drivers/mtd/spi-nor/Kconfig       |   7 +
>  drivers/mtd/spi-nor/Makefile      |   1 +
>  drivers/mtd/spi-nor/mtk-quadspi.c | 486 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 494 insertions(+)
>  create mode 100644 drivers/mtd/spi-nor/mtk-quadspi.c
> 
> diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
> index 89bf4c1..f433890 100644
> --- a/drivers/mtd/spi-nor/Kconfig
> +++ b/drivers/mtd/spi-nor/Kconfig
> @@ -7,6 +7,13 @@ menuconfig MTD_SPI_NOR
>  
>  if MTD_SPI_NOR
>  
> +config MTD_MT81xx_NOR
> +	tristate "Support SPI flash Controller MTD_MT81xx_NOR"

You don't need to repeat the exact symbol name in the short description.
But you probably should include the name "MediaTek". How about this?

	tristate "MediaTek MT81xx SPI NOR flash controller"

> +	help
> +	  This enables access to SPI Nor flash, using MTD_MT81XX_NOR controller.

s/Nor/NOR/

And again, don't name the controller "MTD_MT81XX_NOR."

> +	  This controller does nor support generic SPI BUS, It only supports

s/nor/not/

> +	  SPI NOR Flash.
> +
>  config MTD_SPI_NOR_USE_4K_SECTORS
>  	bool "Use small 4096 B erase sectors"
>  	default y
> diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
> index e53333e..37c020a 100644
> --- a/drivers/mtd/spi-nor/Makefile
> +++ b/drivers/mtd/spi-nor/Makefile
> @@ -1,3 +1,4 @@
> +obj-$(CONFIG_MTD_MT81xx_NOR)	+= mtk-quadspi.o

Please include this between 'fsl-quadspi' and 'nxp-spifi' (i.e.,
alphabetical order).

>  obj-$(CONFIG_MTD_SPI_NOR)	+= spi-nor.o
>  obj-$(CONFIG_SPI_FSL_QUADSPI)	+= fsl-quadspi.o
>  obj-$(CONFIG_SPI_NXP_SPIFI)	+= nxp-spifi.o
> diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c
> new file mode 100644
> index 0000000..c6ac366
> --- /dev/null
> +++ b/drivers/mtd/spi-nor/mtk-quadspi.c
> @@ -0,0 +1,486 @@
> +/*
> + * Copyright (c) 2015 MediaTek Inc.
> + * Author: Bayi Cheng <[email-masked]>
> + *
> + * 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.
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/ioport.h>
> +#include <linux/math64.h>
> +#include <linux/module.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_gpio.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/partitions.h>
> +#include <linux/mtd/spi-nor.h>
> +
> +#define MTK_NOR_CMD_REG			0x00
> +#define MTK_NOR_CNT_REG			0x04
> +#define MTK_NOR_RDSR_REG		0x08
> +#define MTK_NOR_RDATA_REG		0x0c
> +#define MTK_NOR_RADR0_REG		0x10
> +#define MTK_NOR_RADR1_REG		0x14
> +#define MTK_NOR_RADR2_REG		0x18
> +#define MTK_NOR_WDATA_REG		0x1c
> +#define MTK_NOR_PRGDATA0_REG		0x20
> +#define MTK_NOR_PRGDATA1_REG		0x24
> +#define MTK_NOR_PRGDATA2_REG		0x28
> +#define MTK_NOR_PRGDATA3_REG		0x2c
> +#define MTK_NOR_PRGDATA4_REG		0x30
> +#define MTK_NOR_PRGDATA5_REG		0x34
> +#define MTK_NOR_SHREG0_REG		0x38
> +#define MTK_NOR_SHREG1_REG		0x3c
> +#define MTK_NOR_SHREG2_REG		0x40
> +#define MTK_NOR_SHREG3_REG		0x44
> +#define MTK_NOR_SHREG4_REG		0x48
> +#define MTK_NOR_SHREG5_REG		0x4c
> +#define MTK_NOR_SHREG6_REG		0x50
> +#define MTK_NOR_SHREG7_REG		0x54
> +#define MTK_NOR_SHREG8_REG		0x58
> +#define MTK_NOR_SHREG9_REG		0x5c
> +#define MTK_NOR_CFG1_REG		0x60
> +#define MTK_NOR_CFG2_REG		0x64
> +#define MTK_NOR_CFG3_REG		0x68
> +#define MTK_NOR_STATUS0_REG		0x70
> +#define MTK_NOR_STATUS1_REG		0x74
> +#define MTK_NOR_STATUS2_REG		0x78
> +#define MTK_NOR_STATUS3_REG		0x7c
> +#define MTK_NOR_FLHCFG_REG		0x84
> +#define MTK_NOR_TIME_REG		0x94
> +#define MTK_NOR_PP_DATA_REG		0x98
> +#define MTK_NOR_PREBUF_STUS_REG		0x9c
> +#define MTK_NOR_DELSEL0_REG		0xa0
> +#define MTK_NOR_DELSEL1_REG		0xa4
> +#define MTK_NOR_INTRSTUS_REG		0xa8
> +#define MTK_NOR_INTREN_REG		0xac
> +#define MTK_NOR_CHKSUM_CTL_REG		0xb8
> +#define MTK_NOR_CHKSUM_REG		0xbc
> +#define MTK_NOR_CMD2_REG		0xc0
> +#define MTK_NOR_WRPROT_REG		0xc4
> +#define MTK_NOR_RADR3_REG		0xc8
> +#define MTK_NOR_DUAL_REG		0xcc
> +#define MTK_NOR_DELSEL2_REG		0xd0
> +#define MTK_NOR_DELSEL3_REG		0xd4
> +#define MTK_NOR_DELSEL4_REG		0xd8
> +
> +/* commands for mtk nor controller */
> +#define MTK_NOR_READ_CMD		0x0
> +#define MTK_NOR_RDSR_CMD		0x2
> +#define MTK_NOR_PRG_CMD			0x4
> +#define MTK_NOR_WR_CMD			0x10
> +#define MTK_NOR_PIO_WR_CMD		0x90
> +#define MTK_NOR_WRSR_CMD		0x20
> +#define MTK_NOR_PIO_READ_CMD		0x81
> +#define MTK_NOR_WR_BUF_ENABLE		0x1
> +#define MTK_NOR_WR_BUF_DISABLE		0x0
> +#define MTK_NOR_ENABLE_SF_CMD		0x30
> +#define MTK_NOR_DUAD_ADDR_EN		0x8
> +#define MTK_NOR_QUAD_READ_EN		0x4
> +#define MTK_NOR_DUAL_ADDR_EN		0x2
> +#define MTK_NOR_DUAL_READ_EN		0x1
> +#define MTK_NOR_DUAL_DISABLE		0x0
> +#define MTK_NOR_FAST_READ		0x1
> +
> +#define SFLASH_WRBUF_SIZE		128
> +
> +struct mt8173_nor {
> +	struct mtd_info mtd;
> +	struct spi_nor nor;
> +	struct device *dev;
> +	void __iomem *base;	/* nor flash base address */
> +	struct clk *spi_clk;
> +	struct clk *nor_clk;
> +};
> +
> +static void mt8173_nor_set_read_mode(struct mt8173_nor *mt8173_nor)
> +{
> +	struct spi_nor *nor = &mt8173_nor->nor;
> +
> +	switch (nor->flash_read) {
> +	case SPI_NOR_FAST:
> +		writeb(SPINOR_OP_READ_FAST, mt8173_nor->base +

The SPINOR_OP_READ_xxx is just nor->read_opcode. Same for all the other
cases. So you can pull the writeb() out of the switch block.

> +		       MTK_NOR_PRGDATA3_REG);
> +		writeb(MTK_NOR_FAST_READ, mt8173_nor->base +
> +		       MTK_NOR_CFG1_REG);
> +		break;
> +	case SPI_NOR_DUAL:
> +		writeb(SPINOR_OP_READ_1_1_2, mt8173_nor->base +
> +		       MTK_NOR_PRGDATA3_REG);
> +		writeb(MTK_NOR_DUAL_READ_EN, mt8173_nor->base +
> +		       MTK_NOR_DUAL_REG);
> +		break;
> +	case SPI_NOR_QUAD:
> +		writeb(SPINOR_OP_READ_1_1_4, mt8173_nor->base +
> +		       MTK_NOR_PRGDATA3_REG);
> +		writeb(MTK_NOR_QUAD_READ_EN, mt8173_nor->base +
> +		       MTK_NOR_DUAL_REG);
> +		break;
> +	default:
> +		writeb(SPINOR_OP_READ, mt8173_nor->base +
> +		       MTK_NOR_PRGDATA3_REG);
> +		writeb(MTK_NOR_DUAL_DISABLE, mt8173_nor->base +
> +		       MTK_NOR_DUAL_REG);
> +		break;
> +	}
> +}
> +
> +static int mt8173_nor_execute_cmd(struct mt8173_nor *mt8173_nor, u8 cmdval)
> +{
> +	int reg;
> +	u8 val = cmdval & 0x1f;
> +
> +	writeb(cmdval, mt8173_nor->base + MTK_NOR_CMD_REG);
> +	return readl_poll_timeout(mt8173_nor->base + MTK_NOR_CMD_REG, reg,
> +				  !(reg & val), 100, 10000);
> +}
> +
> +static int mt8173_nor_set_cmd(struct mt8173_nor *mt8173_nor, int addr, u8 len,
> +			      u8 op)

This function protype looks all wrong, and it seems you're not using it
to its full potential either.

What you have is the ability to write an opcode and up to 5 bytes
following it. For several cases, 3 of those following it are just
address bytes. But what about 4-byte addressing (needed on larger
flash)? And what about opcodes you didn't prepare for?

So, I believe you can rewrite this function to be more like:

static int mt8173_nor_do_tx(struct mt8173_nor *mt8173_nor, u8 op, u8 *buf,
			    int len)
{
	int i;

	if (len > 5)
		return -EINVAL;

	writeb(op, mt8173_nor->base + MTK_NOR_PRGDATA5_REG);

	for (i = 0; i < len; i++)
		writeb(buf[i], mt8173_nor->base +
			       MTK_NOR_PRGDATA0_REG + 4 * (4 - i));
	writeb((len + 1) * 8, mt8173_nor->base + MTK_NOR_CNT_REG);
	return mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_PRG_CMD);
}

So existing uses like this:

		ret = mt8173_nor_set_cmd(mt8173_nor, 0, 8, opcode);

can instead look like this:

		ret = mt8173_nor_do_tx(mt8173_nor, opcode, NULL, 0);

But you can also do more general write_reg() transfers with:

		ret = mt8173_nor_do_tx(mt8173_nor, opcode, buf, len);

I make similar comments below. I believe I've made these comments
previoulsy. If you have questions, please ask instead of just submitting
another version that doesn't really address my comment.

> +{
> +	writeb(op, mt8173_nor->base + MTK_NOR_PRGDATA5_REG);
> +	/*  send the address to nor flash
> +	 *  MTK_NOR_PRGDATA5_REG is shifted first
> +	 */
> +	if (len > 8) {
> +		writeb((addr >> 16), mt8173_nor->base + MTK_NOR_PRGDATA4_REG);
> +		writeb((addr >> 8), mt8173_nor->base + MTK_NOR_PRGDATA3_REG);
> +		writeb((addr), mt8173_nor->base + MTK_NOR_PRGDATA2_REG);
> +	}
> +	writeb(len, mt8173_nor->base + MTK_NOR_CNT_REG);
> +	return mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_PRG_CMD);
> +}
> +
> +/* cmd1 sent to nor flash, cmd2 write to nor controller */
> +static int mt8173_nor_set_para(struct mt8173_nor *mt8173_nor, int cmd1,
> +			       int cmd2)
> +{
> +	int ret;
> +
> +	ret = mt8173_nor_set_cmd(mt8173_nor, 0, 8, SPINOR_OP_WREN);
> +	if (ret < 0)
> +		return ret;

Why do you need this? You're just reimplementing write_enable() from
spi-nor.c, which should already get called in the right places. If it's
not, then fix that instead of hacking it in here.

Same applies in your erase function.

> +
> +	writeb(cmd1, mt8173_nor->base + MTK_NOR_PRGDATA5_REG);
> +	writeb(8, mt8173_nor->base + MTK_NOR_CNT_REG);
> +	return mt8173_nor_execute_cmd(mt8173_nor, cmd2);
> +}
> +
> +static int mt8173_nor_write_buffer_enable(struct mt8173_nor *mt8173_nor)
> +{
> +	u8 reg;
> +
> +	/* the bit0 of MTK_NOR_CFG2_REG is pre-fetch buffer
> +	 * 0: pre-fetch buffer use for read
> +	 * 1: pre-fetch buffer use for page program
> +	 */
> +	writel(MTK_NOR_WR_BUF_ENABLE, mt8173_nor->base + MTK_NOR_CFG2_REG);
> +	return readb_poll_timeout(mt8173_nor->base + MTK_NOR_CFG2_REG, reg,
> +				  0x01 == (reg & 0x01), 100, 10000);
> +}
> +
> +static int mt8173_nor_write_buffer_disable(struct mt8173_nor *mt8173_nor)
> +{
> +	u8 reg;
> +
> +	writel(MTK_NOR_WR_BUF_DISABLE, mt8173_nor->base + MTK_NOR_CFG2_REG);
> +	return readb_poll_timeout(mt8173_nor->base + MTK_NOR_CFG2_REG, reg,
> +				  MTK_NOR_WR_BUF_DISABLE == (reg & 0x1), 100,
> +				  10000);
> +}
> +
> +static int mt8173_nor_erase_sector(struct spi_nor *nor, loff_t offset)
> +{
> +	int ret;
> +	struct mt8173_nor *mt8173_nor = nor->priv;
> +
> +	ret = mt8173_nor_set_cmd(mt8173_nor, 0, 8, SPINOR_OP_WREN);
> +	if (ret < 0)
> +		return ret;

Same comment here. You shouldn't need the WREN.

> +
> +	return mt8173_nor_set_cmd(mt8173_nor, (int)offset, 32, SPINOR_OP_BE_4K);
> +}
> +
> +static int mt8173_nor_read(struct spi_nor *nor, loff_t from, size_t length,
> +			   size_t *retlen, u_char *buffer)
> +{
> +	int i, ret;
> +	int addr = (int)from;
> +	u8 *buf = (u8 *)buffer;
> +	struct mt8173_nor *mt8173_nor = nor->priv;
> +
> +	/* set mode for fast read mode ,dual mode or quad mode */
> +	mt8173_nor_set_read_mode(mt8173_nor);
> +	writeb((addr >> 24), mt8173_nor->base + MTK_NOR_RADR3_REG);
> +	writeb((addr >> 16), mt8173_nor->base + MTK_NOR_RADR2_REG);
> +	writeb((addr >> 8), mt8173_nor->base + MTK_NOR_RADR1_REG);
> +	writeb(addr, mt8173_nor->base + MTK_NOR_RADR0_REG);
> +
> +	for (i = 0; i < length; i++, (*retlen)++) {
> +		ret = mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_PIO_READ_CMD);
> +		if (ret < 0)
> +			return ret;
> +		buf[i] = readb(mt8173_nor->base + MTK_NOR_RDATA_REG);
> +	}
> +	return 0;
> +}
> +
> +static int mt8173_nor_write_single_byte(struct mt8173_nor *mt8173_nor,
> +					int addr, int length, u8 *data)
> +{
> +	int i, ret;
> +
> +	writeb((addr >> 24), mt8173_nor->base + MTK_NOR_RADR3_REG);
> +	writeb((addr >> 16), mt8173_nor->base + MTK_NOR_RADR2_REG);
> +	writeb((addr >> 8), mt8173_nor->base + MTK_NOR_RADR1_REG);
> +	writeb(addr, mt8173_nor->base + MTK_NOR_RADR0_REG);
> +
> +	for (i = 0; i < length; i++) {
> +		ret = mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_PIO_WR_CMD);
> +		if (ret < 0)
> +			return ret;
> +		writeb(*data++, mt8173_nor->base + MTK_NOR_WDATA_REG);
> +	}
> +	return 0;
> +}
> +
> +static int mt8173_nor_write_buffer(struct mt8173_nor *mt8173_nor, int addr,
> +				   const u8 *buf)
> +{
> +	int i, bufidx, data;
> +
> +	writeb((addr >> 24), mt8173_nor->base + MTK_NOR_RADR3_REG);
> +	writeb((addr >> 16), mt8173_nor->base + MTK_NOR_RADR2_REG);
> +	writeb((addr >> 8), mt8173_nor->base + MTK_NOR_RADR1_REG);
> +	writeb(addr, mt8173_nor->base + MTK_NOR_RADR0_REG);
> +
> +	bufidx = 0;
> +	for (i = 0; i < SFLASH_WRBUF_SIZE; i += 4) {
> +		data = buf[bufidx + 3]<<24 | buf[bufidx + 2]<<16 |
> +		       buf[bufidx + 1]<<8 | buf[bufidx];
> +		bufidx += 4;
> +		writel(data, mt8173_nor->base + MTK_NOR_PP_DATA_REG);
> +	}
> +	return mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_WR_CMD);
> +}
> +
> +static void mt8173_nor_write(struct spi_nor *nor, loff_t to, size_t len,
> +			     size_t *retlen, const u_char *buf)
> +{
> +	int ret;
> +	struct mt8173_nor *mt8173_nor = nor->priv;
> +
> +	ret = mt8173_nor_write_buffer_enable(mt8173_nor);
> +	if (ret < 0)
> +		dev_warn(mt8173_nor->dev, "write buffer enable failed!\n");
> +
> +	while (len >= SFLASH_WRBUF_SIZE) {
> +		ret = mt8173_nor_write_buffer(mt8173_nor, to, buf);
> +		if (ret < 0)
> +			dev_warn(mt8173_nor->dev, "write buffer failed!\n");
> +		len -= SFLASH_WRBUF_SIZE;
> +		to += SFLASH_WRBUF_SIZE;
> +		buf += SFLASH_WRBUF_SIZE;
> +		(*retlen) += SFLASH_WRBUF_SIZE;
> +	}
> +	ret = mt8173_nor_write_buffer_disable(mt8173_nor);
> +	if (ret < 0)
> +		dev_warn(mt8173_nor->dev, "write buffer disable failed!\n");
> +
> +	if (len) {
> +		ret = mt8173_nor_write_single_byte(mt8173_nor, to, (int)len,
> +						   (u8 *)buf);
> +		if (ret < 0)
> +			dev_warn(mt8173_nor->dev, "write single byte failed!\n");
> +		(*retlen) += len;
> +	}
> +}
> +
> +static int mt8173_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
> +{
> +	int ret;
> +	struct mt8173_nor *mt8173_nor = nor->priv;
> +
> +	/* mtk nor controller doesn't supoort SPINOR_OP_RDCR */
> +	switch (opcode) {
> +	case SPINOR_OP_RDID:
> +		/* read JEDEC ID need 4 bytes commands */
> +		ret = mt8173_nor_set_cmd(mt8173_nor, 0, 32, SPINOR_OP_RDID);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* mtk nor flash controller only support 3 bytes IDs */

Are you absolutely sure of this? That would be highly unfortunate, but
I also don't believe it's true.

> +		buf[2] = readb(mt8173_nor->base + MTK_NOR_SHREG0_REG);
> +		buf[1] = readb(mt8173_nor->base + MTK_NOR_SHREG1_REG);
> +		buf[0] = readb(mt8173_nor->base + MTK_NOR_SHREG2_REG);
> +		break;
> +	case SPINOR_OP_RDSR:
> +		ret = mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_RDSR_CMD);
> +		if (ret < 0)
> +			return ret;
> +		*buf = readb(mt8173_nor->base + MTK_NOR_RDSR_REG);
> +		break;
> +	default:
> +		ret = -EINVAL;

Why have you only implemented RDSR and RDID? What stops you from
supporting other opcodes here? It's a generic programming pattern, so
make this function generic. If you have limitations (e.g., you can only
read up to 6 bytes), then just make them explicit, with something like:

	/* Can only read out xxx bytes per command */
	if (len > xxx)
		return -EINVAL;

Really, I think you can just make a little modification to my sample
mt8173_nor_do_tx() function and make a mt8173_nor_do_rx() function that
will handle a few bytes of register read.

> +		break;
> +	}
> +	return ret;
> +}
> +
> +static int mt8173_nor_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
> +				int len)
> +{
> +	int ret;
> +	struct mt8173_nor *mt8173_nor = nor->priv;
> +
> +	switch (opcode) {
> +	case SPINOR_OP_WRSR:
> +		ret = mt8173_nor_set_para(mt8173_nor, *buf,
> +					  MTK_NOR_WRSR_CMD);
> +		break;
> +	case SPINOR_OP_CHIP_ERASE:
> +		ret = mt8173_nor_set_para(mt8173_nor, opcode,
> +					  MTK_NOR_PRG_CMD);
> +		break;
> +	case SPINOR_OP_WREN:

This case is the same as...

> +		ret = mt8173_nor_set_cmd(mt8173_nor, 0, 8, opcode);
> +		if (ret)
> +			dev_warn(mt8173_nor->dev, "set write enable fail!\n");
> +		break;
> +	case SPINOR_OP_WRDI:

... this one.

So why duplicate them?

> +		ret = mt8173_nor_set_cmd(mt8173_nor, 0, 8, opcode);
> +		if (ret)
> +			dev_warn(mt8173_nor->dev, "set write disable fail!\n");
> +		break;
> +	default:
> +		dev_warn(mt8173_nor->dev, "doesn't support cmd %d\n", opcode);
> +		ret = -EINVAL;

Again, why are you restricting support here? It looks like
mt8173_nor_set_cmd() can handle generic opcodes.

> +		break;
> +	}
> +	return ret;
> +}
> +
> +static int __init mtk_nor_init(struct mt8173_nor *mt8173_nor,
> +			       struct mtd_part_parser_data *ppdata)
> +{
> +	int ret;
> +	struct spi_nor *nor;
> +	struct mtd_info *mtd;
> +
> +	writel(MTK_NOR_ENABLE_SF_CMD, mt8173_nor->base + MTK_NOR_WRPROT_REG);
> +	nor = &mt8173_nor->nor;
> +	mtd = &mt8173_nor->mtd;
> +	nor->mtd = *mtd;

Yikes! I don't think you want to copy the entire struct here. Just drop
the 'mtd' field in struct mt8173_nor, since we now have the mtd_info
struct embedded inside struct spi_nor.

> +	nor->dev = mt8173_nor->dev;
> +	nor->priv = mt8173_nor;
> +	mtd->priv = nor;
> +
> +	/* fill the hooks to spi nor */
> +	nor->read = mt8173_nor_read;
> +	nor->read_reg = mt8173_nor_read_reg;
> +	nor->write = mt8173_nor_write;
> +	nor->write_reg = mt8173_nor_write_reg;
> +	nor->erase = mt8173_nor_erase_sector;
> +	nor->mtd.owner = THIS_MODULE;
> +	nor->mtd.name = "mtk_nor";
> +	/* initialized with NULL */
> +	ret = spi_nor_scan(nor, NULL, SPI_NOR_DUAL);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(mt8173_nor->dev, "mtd->size :0x%llx!\n", mtd->size);

Please remove this. This information is readily available in plenty of
other ways.

> +	return  mtd_device_parse_register(&nor->mtd, NULL, ppdata, NULL, 0);
> +}
> +
> +static int mtk_nor_drv_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct mtd_part_parser_data ppdata;
> +	struct resource *res;
> +	int ret;
> +	struct mt8173_nor *mt8173_nor;
> +
> +	if (!pdev->dev.of_node) {
> +		dev_err(&pdev->dev, "No DT found\n");
> +		return -EINVAL;
> +	}
> +
> +	mt8173_nor = devm_kzalloc(&pdev->dev, sizeof(*mt8173_nor), GFP_KERNEL);
> +	if (!mt8173_nor)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, mt8173_nor);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mt8173_nor->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(mt8173_nor->base))
> +		return PTR_ERR(mt8173_nor->base);
> +
> +	mt8173_nor->spi_clk = devm_clk_get(&pdev->dev, "spi");
> +	if (IS_ERR(mt8173_nor->spi_clk)) {
> +		ret = PTR_ERR(mt8173_nor->spi_clk);
> +		goto nor_free;
> +	}
> +
> +	mt8173_nor->nor_clk = devm_clk_get(&pdev->dev, "sf");
> +	if (IS_ERR(mt8173_nor->nor_clk)) {
> +		ret = PTR_ERR(mt8173_nor->nor_clk);
> +		goto nor_free;
> +	}
> +
> +	mt8173_nor->dev = &pdev->dev;
> +	clk_prepare_enable(mt8173_nor->spi_clk);
> +	clk_prepare_enable(mt8173_nor->nor_clk);
> +
> +	ppdata.of_node = np;

On an earlier version, I suggested that you use a subnode to represent
the flash(es), even if you're only planning to ever use one flash. I
don't see that represented here though.

Also, please assign nor->flash_node somewhere in this init routine.

> +	ret = mtk_nor_init(mt8173_nor, &ppdata);
> +
> +nor_free:
> +	return ret;
> +}
> +
> +static int mtk_nor_drv_remove(struct platform_device *pdev)
> +{
> +	struct mt8173_nor *mt8173_nor = platform_get_drvdata(pdev);
> +
> +	mtd_device_unregister(&mt8173_nor->mtd);
> +	clk_disable_unprepare(mt8173_nor->spi_clk);
> +	clk_disable_unprepare(mt8173_nor->nor_clk);
> +	return 0;
> +}
> +
> +static const struct of_device_id mtk_nor_of_ids[] = {
> +	{ .compatible = "mediatek,mt8173-nor"},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mtk_nor_of_ids);
> +
> +static struct platform_driver mtk_nor_driver = {
> +	.probe = mtk_nor_drv_probe,
> +	.remove = mtk_nor_drv_remove,
> +	.driver = {
> +		.name = "mtk-nor",
> +		.of_match_table = mtk_nor_of_ids,
> +	},
> +};
> +
> +module_platform_driver(mtk_nor_driver);
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("MediaTek SPI NOR Flash Driver");

Brian