Message-ID: <20150528013208.GM27753@ld-irv-0074>
Date:	Wed, 27 May 2015 18:32:08 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	vndao@...era.com
Cc:	dwmw2@...radead.org, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	ngachi86@...il.com
Subject: Re: [PATCH] [PATCH v3] mtd:spi-nor: Add Altera Quad SPI Driver

Hi Nga,

Sorry for some delay here. This driver is mostly pretty good, and I
think only a few very small tweaks are needed.

(BTW, Rafal already made a few tiny comments, and I didn't see a follow
up that fixes any of them.)

On Mon, Mar 16, 2015 at 01:16:22AM -0700, vndao@...era.com wrote:
> From: VIET NGA DAO <vndao@...era.com>
> 
> Altera Quad SPI Controller is a soft IP which enables access to Altera EPCQ and
> EPCS flash chips. This patch adds driver for these devices.
> 
> Signed-off-by: VIET NGA DAO <vndao@...era.com>
> 
> ---
> v3:
> - Change altera_epcq driver name to altera_quadspi for more generic name
> - Implement flash name searching in altera_quadspi.c instead of spi-nor
> - Edit the altra quadspi info table in spi-nor
> - Remove wait_til_ready in all read,write, erase, lock, unlock functions
> - Merge .h and .c into 1 file
> 
> v2:
> - Change to spi_nor structure
> - Add lock and unlock functions for spi_nor
> - Simplify the altera_epcq_lock function
> - Replace reg by compatible in device tree
> ---
>  .../devicetree/bindings/mtd/altera_quadspi.txt     |  45 ++
>  drivers/mtd/spi-nor/Kconfig                        |   8 +
>  drivers/mtd/spi-nor/Makefile                       |   1 +
>  drivers/mtd/spi-nor/altera_quadspi.c               | 608 +++++++++++++++++++++
>  drivers/mtd/spi-nor/spi-nor.c                      |  11 +
>  5 files changed, 673 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/altera_quadspi.txt
>  create mode 100644 drivers/mtd/spi-nor/altera_quadspi.c
> 
> diff --git a/Documentation/devicetree/bindings/mtd/altera_quadspi.txt b/Documentation/devicetree/bindings/mtd/altera_quadspi.txt
> new file mode 100644
> index 0000000..f5bdd35
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/altera_quadspi.txt
> @@ -0,0 +1,45 @@
> +* MTD Altera QUADSPI driver
> +
> +Required properties:
> +- compatible: Should be "altr,quadspi-1.0"
> +- reg: Address and length of the register set  for the device. It contains
> +  the information of registers in the same order as described by reg-names
> +- reg-names: Should contain the reg names
> +  "csr_base": Should contain the register configuration base address
> +  "data_base": Should contain the data base address
> +- is-epcs: boolean type.
> +		If present, the device contains EPCS flashes.
> +		Otherwise, it contains EPCQ flashes.

Is this a property of the controller, or the flash? Seems like it should
be in the subnode(s).

> +- #address-cells: Must be <1>.
> +- #size-cells: Must be <0>.
> +- flash device tree subnode, there must be a node with the following fields:
> +	- compatible: Should contain the flash name

You should list the names here.

> +	- #address-cells: please refer to /mtd/partition.txt
> +	- #size-cells: please refer to /mtd/partition.txt
> +	For partitions inside each flash, please refer to /mtd/partition.txt
> +
> +Example:
> +
> +			quadspi_controller_0: quadspi@...00000000 {
> +				compatible = "altr,quadspi-1.0";
> +				reg = <0x00000001 0x00000000 0x00000020>,
> +					<0x00000000 0x00000000 0x02000000>;
> +				reg-names = "csr_base", "data_base";
> +				#address-cells = <1>;
> +				#size-cells = <0>;
> +				flash0: epcq256@0 {
> +					compatible = "epcq256-nonjedec";

I don't think the "-nonjedec" part is necessary; it's not really
relevant to the binding, and it probably isn't even necessary for the ID
table in spi-nor.c. Just stick with names like "altr,epcq256". But you
probably should include the "altr," prefix. That will still work fine
with the modalias stuff.

> +					#address-cells = <1>;
> +					#size-cells = <1>;
> +					partition@0 {
> +						/* 16 MB for raw data. */
> +						label = "EPCQ Flash 0 raw data";
> +						reg = <0x0 0x1000000>;
> +					};
> +					partition@...0000 {
> +						/* 16 MB for jffs2 data. */
> +						label = "EPCQ Flash 0 JFFS 2";
> +						reg = <0x1000000 0x1000000>;
> +					};
> +				};
> +			}; //end quadspi@...00000000 (quadspi_controller_0)
> diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
> index 64a4f0e..b9eed6d 100644
> --- a/drivers/mtd/spi-nor/Kconfig
> +++ b/drivers/mtd/spi-nor/Kconfig
> @@ -28,4 +28,12 @@ config SPI_FSL_QUADSPI
>  	  This enables support for the Quad SPI controller in master mode.
>  	  We only connect the NOR to this controller now.
>  
> +config SPI_ALTERA_QUADSPI
> +	tristate "Support Altera EPCQ/EPCS Flash chips"
> +	depends on OF
> +	help
> +	  This enables access to Altera EPCQ/EPCS flash chips, used for data
> +	  storage. See the driver source for the current list,
> +	  or to add other chips.
> +
>  endif # MTD_SPI_NOR
> diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
> index 6a7ce14..1a36a72 100644
> --- a/drivers/mtd/spi-nor/Makefile
> +++ b/drivers/mtd/spi-nor/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_MTD_SPI_NOR)	+= spi-nor.o
>  obj-$(CONFIG_SPI_FSL_QUADSPI)	+= fsl-quadspi.o
> +obj-$(CONFIG_SPI_ALTERA_QUADSPI)	+= altera_quadspi.o
> diff --git a/drivers/mtd/spi-nor/altera_quadspi.c b/drivers/mtd/spi-nor/altera_quadspi.c

Probably just use hyphens ("-") in the file name, not underscores ("_")
to match the other files in that dir.

> new file mode 100644
> index 0000000..1d178d9
> --- /dev/null
> +++ b/drivers/mtd/spi-nor/altera_quadspi.c
> @@ -0,0 +1,608 @@
> +/*
> + * Copyright (C) 2014 Altera Corporation. All rights reserved
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/log2.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/partitions.h>
> +#include <linux/mtd/spi-nor.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/sched.h>
> +
> +#define ALTERA_QUADSPI_RESOURCE_NAME			"altera_quadspi"
> +
> +/* max possible slots for serial flash chip in the QUADSPI controller */
> +#define MAX_NUM_FLASH_CHIP				3
> +#define EPCS_OPCODE_ID					1
> +#define EPCQ_OPCODE_ID					2
> +#define WRITE_CHECK					1
> +#define ERASE_CHECK					0
> +
> +/* Define max times to check status register before we give up. */
> +#define QUADSPI_MAX_TIME_OUT				(40 * HZ)
> +
> +/* defines for status register */
> +#define QUADSPI_SR_REG					0x0
> +#define QUADSPI_SR_WIP_MASK				0x00000001
> +#define QUADSPI_SR_WIP					0x1
> +#define QUADSPI_SR_WEL					0x2
> +#define QUADSPI_SR_BP0					0x4
> +#define QUADSPI_SR_BP1					0x8
> +#define QUADSPI_SR_BP2					0x10
> +#define QUADSPI_SR_BP3					0x40
> +#define QUADSPI_SR_TB					0x20
> +#define QUADSPI_SR_MASK					0x0000000F
> +
> +/* defines for device id register */
> +#define QUADSPI_SID_REG					0x4
> +#define QUADSPI_RDID_REG				0x8
> +#define QUADSPI_ID_MASK					0x000000FF
> +
> +/*
> + * QUADSPI_MEM_OP register offset
> + *
> + * The QUADSPI_MEM_OP register is used to do memory protect and erase operations
> + *
> + */
> +#define QUADSPI_MEM_OP_REG				0xC
> +
> +#define QUADSPI_MEM_OP_CMD_MASK				0x00000003
> +#define QUADSPI_MEM_OP_BULK_ERASE_CMD			0x00000001
> +#define QUADSPI_MEM_OP_SECTOR_ERASE_CMD			0x00000002
> +#define QUADSPI_MEM_OP_SECTOR_PROTECT_CMD		0x00000003
> +#define QUADSPI_MEM_OP_SECTOR_VALUE_MASK		0x0003FF00
> +#define QUADSPI_MEM_OP_SECTOR_PROTECT_VALUE_MASK	0x00001F00
> +#define QUADSPI_MEM_OP_SECTOR_PROTECT_SHIFT		8
> +/*
> + * QUADSPI_ISR register offset
> + *
> + * The QUADSPI_ISR register is used to determine whether an invalid write or
> + * erase operation trigerred an interrupt
> + *
> + */
> +#define QUADSPI_ISR_REG					0x10
> +
> +#define QUADSPI_ISR_ILLEGAL_ERASE_MASK			0x00000001
> +#define QUADSPI_ISR_ILLEGAL_WRITE_MASK			0x00000002
> +
> +/*
> + * QUADSPI_IMR register offset
> + *
> + * The QUADSPI_IMR register is used to mask the invalid erase or the invalid
> + * write interrupts.
> + *
> + */
> +#define QUADSPI_IMR_REG					0x14
> +#define QUADSPI_IMR_ILLEGAL_ERASE_MASK			0x00000001
> +
> +#define QUADSPI_IMR_ILLEGAL_WRITE_MASK			0x00000002
> +
> +#define QUADSPI_CHIP_SELECT_REG				0x18
> +#define QUADSPI_CHIP_SELECT_MASK			0x00000007
> +#define QUADSPI_CHIP_SELECT_0				0x00000001
> +#define QUADSPI_CHIP_SELECT_1				0x00000002
> +#define QUADSPI_CHIP_SELECT_2				0x00000004
> +
> +struct altera_quadspi_plat {
> +	void __iomem *csr_base;
> +	void __iomem *data_base;
> +	bool is_epcs;
> +	u32 num_flashes;
> +	struct device_node *np[MAX_NUM_FLASH_CHIP];
> +};
> +
> +struct altera_quadspi {
> +	struct clk *clk;
> +	bool is_epcs;
> +	void __iomem *csr_base;
> +	void __iomem *data_base;
> +	u32 num_flashes;
> +	struct altera_quadspi_flash *flash[MAX_NUM_FLASH_CHIP];
> +};
> +
> +struct altera_quadspi_flash {
> +	struct mtd_info mtd;
> +	struct spi_nor nor;
> +	void *priv;

Does this really need to be 'void *'? Looks like it should be 'struct
altera_quadspi *'.

> +};
> +
> +struct flash_device {
> +	char *name;
> +	u8 opcode_id;
> +	u32 device_id;
> +};
> +
> +#define FLASH_ID(_n, _opcode_id, _id)	\
> +{					\
> +	.name = (_n),			\
> +	.opcode_id = (_opcode_id),	\
> +	.device_id = (_id),		\
> +}
> +
> +static struct flash_device flash_devices[] = {
> +	FLASH_ID("epcq16-nonjedec",  2, 0x15),
> +	FLASH_ID("epcq32-nonjedec",  2, 0x16),
> +	FLASH_ID("epcq64-nonjedec",  2, 0x17),
> +	FLASH_ID("epcq128-nonjedec", 2, 0x18),
> +	FLASH_ID("epcq256-nonjedec", 2, 0x19),
> +	FLASH_ID("epcq512-nonjedec", 2, 0x20),
> +
> +	FLASH_ID("epcs16-nonjedec",  1, 0x14),
> +	FLASH_ID("epcs64-nonjedec",  1, 0x16),
> +	FLASH_ID("epcs128-nonjedec", 1, 0x18),

Rafal commented on this block, about *_OPCODE_ID.

> +};
> +
> +static int altera_quadspi_write_reg(struct spi_nor *nor, u8 opcode, u8 *val,
> +				    int len, int wr_en)
> +{
> +	return 0;
> +}
> +
> +static int altera_quadspi_read_reg(struct spi_nor *nor, u8 opcode, u8 *val,
> +				   int len)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	u32 data = 0;
> +
> +	switch (opcode) {
> +	case SPINOR_OP_RDSR:
> +		data = readl(dev->csr_base + QUADSPI_SR_REG);
> +		*val = (u8)data & QUADSPI_SR_MASK;
> +		break;
> +	case SPINOR_OP_RDID:
> +		/* opcode id */
> +		if (dev->is_epcs)
> +			data = readl(dev->csr_base + QUADSPI_SID_REG);
> +		else
> +			data = readl(dev->csr_base + QUADSPI_RDID_REG);
> +
> +		*val = (u8)data & QUADSPI_ID_MASK; /* device id */
> +		break;
> +	default:
> +		*val = 0;
> +		break;

Zero out the rest of val, since you're only filling the first byte?

> +	}
> +	return 0;
> +}
> +
> +static int altera_quadspi_write_erase_check(struct spi_nor *nor,
> +					    bool write_erase)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	u32 val;
> +	u32 mask;
> +
> +	if (write_erase)
> +		mask = QUADSPI_ISR_ILLEGAL_WRITE_MASK;
> +	else
> +		mask = QUADSPI_ISR_ILLEGAL_ERASE_MASK;
> +
> +	val = readl(dev->csr_base + QUADSPI_ISR_REG);
> +	if (val & mask) {
> +		dev_err(nor->dev,
> +			"write/erase failed, sector might be protected\n");
> +		/* clear this status for next use */
> +		writel(val, dev->csr_base + QUADSPI_ISR_REG);
> +		return -EIO;
> +	}
> +	return 0;
> +}
> +
> +static int altera_quadspi_addr_to_sector(struct mtd_info *mtd, int offset)
> +{
> +	if (mtd->erasesize_shift)
> +		return offset >> mtd->erasesize_shift;
> +	do_div(offset, mtd->erasesize);
> +	return offset;
> +}
> +
> +static int altera_quadspi_erase(struct spi_nor *nor, loff_t offset)
> +{
> +
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	struct mtd_info *mtd = &flash->mtd;
> +	u32 val;
> +	int ret;
> +	int sector_value;
> +
> +	sector_value = altera_quadspi_addr_to_sector(mtd, offset);
> +	/* sanity check that block_offset is a valid sector number */
> +	if (sector_value < 0)
> +		return -EINVAL;
> +
> +	/* sector value should occupy bits 17:8 */
> +	val = (sector_value << 8) & QUADSPI_MEM_OP_SECTOR_VALUE_MASK;
> +
> +	/* sector erase commands occupies lower 2 bits */
> +	val |= QUADSPI_MEM_OP_SECTOR_ERASE_CMD;
> +
> +	/* write sector erase command to QUADSPI_MEM_OP register */
> +	writel(val, dev->csr_base + QUADSPI_MEM_OP_REG);
> +
> +	ret = altera_quadspi_write_erase_check(nor, ERASE_CHECK);
> +	if (ret < 0) {
> +		dev_err(nor->dev, "illegal erase\n");
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static int altera_quadspi_read(struct spi_nor *nor, loff_t from, size_t len,
> +			       size_t *retlen, u_char *buf)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +
> +	memcpy_fromio(buf, dev->data_base + from, len);
> +	*retlen = len;
> +
> +	return 0;
> +}
> +
> +static void altera_quadspi_write(struct spi_nor *nor, loff_t to, size_t len,
> +				 size_t *retlen, const u_char *buf)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	int ret = 0;
> +
> +	memcpy_toio(dev->data_base + to, buf, len);
> +	*retlen += len;
> +
> +	/*
> +	 * check whether write triggered a illegal write interrupt
> +	 */
> +
> +	ret = altera_quadspi_write_erase_check(nor, WRITE_CHECK);
> +	if (ret < 0)
> +		dev_err(nor->dev, "illegal write\n");
> +
> +
> +}
> +
> +static int altera_quadspi_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	struct mtd_info *mtd = &flash->mtd;
> +	uint32_t offset = ofs;
> +	u32 sector_start, sector_end;
> +	u32 num_sectors;
> +	u32 mem_op;
> +	u32 sr_bp;
> +	u32 sr_tb;
> +
> +	sector_start = offset;
> +	sector_end = altera_quadspi_addr_to_sector(mtd, offset + len);
> +	num_sectors = mtd->size;
> +	do_div(num_sectors, mtd->erasesize);
> +
> +	dev_dbg(nor->dev, "%s: sector start is %u,sector end is %u\n",
> +		__func__, sector_start, sector_end);
> +
> +	if (sector_start >= num_sectors / 2) {
> +		sr_bp = fls(num_sectors - 1 - sector_start) + 1;
> +		sr_tb = 0;
> +	} else if ((sector_end < num_sectors / 2) && ~dev->is_epcs) {
> +		sr_bp = fls(sector_end) + 1;
> +		sr_tb = 1;
> +	} else {
> +		sr_bp = 16;
> +		sr_tb = 0;
> +	}
> +
> +	mem_op = (sr_tb << 12) | (sr_bp << 8);
> +	mem_op &= QUADSPI_MEM_OP_SECTOR_PROTECT_VALUE_MASK;
> +	mem_op |= QUADSPI_MEM_OP_SECTOR_PROTECT_CMD;
> +	writel(mem_op, dev->csr_base + QUADSPI_MEM_OP_REG);
> +
> +	return 0;
> +}
> +
> +static int altera_quadspi_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	u32 mem_op;
> +
> +	dev_dbg(nor->dev, "Unlock all protected area\n");
> +	mem_op = 0;
> +	mem_op &= QUADSPI_MEM_OP_SECTOR_PROTECT_VALUE_MASK;
> +	mem_op |= QUADSPI_MEM_OP_SECTOR_PROTECT_CMD;

Can't the above 3 lines just be:

	mem_op = QUADSPI_MEM_OP_SECTOR_PROTECT_CMD;

?

> +	writel(mem_op, dev->csr_base + QUADSPI_MEM_OP_REG);
> +
> +	return 0;
> +}
> +
> +static void altera_quadspi_chip_select(struct altera_quadspi *dev, u32 bank)
> +{
> +	u32 val = 0;
> +
> +	switch (bank) {
> +	case 0:
> +		val = QUADSPI_CHIP_SELECT_0;
> +		break;
> +	case 1:
> +		val = QUADSPI_CHIP_SELECT_1;
> +		break;
> +	case 2:
> +		val = QUADSPI_CHIP_SELECT_2;
> +		break;
> +	default:
> +		return;
> +	}
> +	writel(val, dev->csr_base + QUADSPI_CHIP_SELECT_REG);
> +}
> +
> +
> +static int altera_quadspi_probe_config_dt(struct platform_device *pdev,
> +					  struct device_node *np,
> +					  struct altera_quadspi_plat *pdata)
> +{
> +	struct device_node *pp = NULL;

^^ Is the NULL assignment necessary?

> +	struct resource *quadspi_res;
> +	int i = 0;
> +
> +	pdata->is_epcs = of_property_read_bool(np, "is-epcs");
> +
> +	quadspi_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +						   "csr_base");
> +	pdata->csr_base = devm_ioremap_resource(&pdev->dev, quadspi_res);
> +	if (IS_ERR(pdata->csr_base)) {
> +		dev_err(&pdev->dev, "%s: ERROR: failed to map csr base\n",
> +			__func__);
> +		return PTR_ERR(pdata->csr_base);
> +	}
> +
> +	quadspi_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +						   "data_base");
> +	pdata->data_base = devm_ioremap_resource(&pdev->dev, quadspi_res);
> +	if (IS_ERR(pdata->data_base)) {
> +		dev_err(&pdev->dev, "%s: ERROR: failed to map data base\n",
> +			__func__);
> +		return PTR_ERR(pdata->data_base);
> +	}
> +
> +	/* Fill structs for each subnode (flash device) */
> +	for_each_available_child_of_node(np, pp) {
> +		/* Read bank id from DT */
> +		pdata->np[i] = pp;
> +		i++;
> +	}
> +	pdata->num_flashes = i;
> +	return 0;
> +}
> +
> +static const char *get_flash_name(struct spi_nor *nor)
> +{
> +	struct altera_quadspi_flash *flash = nor->priv;
> +	struct altera_quadspi *dev = flash->priv;
> +	int index;
> +	int ret;
> +	u8 id = 0;
> +	u8 opcode_id;
> +
> +	opcode_id = dev->is_epcs ? EPCS_OPCODE_ID : EPCQ_OPCODE_ID;
> +	ret = nor->read_reg(nor, SPINOR_OP_RDID, &id, 1);
> +	if (ret)
> +		return NULL;
> +	for (index = 0; index < ARRAY_SIZE(flash_devices); index++) {
> +		if (flash_devices[index].device_id == id &&
> +		    flash_devices[index].opcode_id == opcode_id)
> +			return flash_devices[index].name;
> +	}
> +
> +	/* Memory chip is not listed and not supported */
> +	return NULL;
> +}
> +
> +static int altera_quadspi_setup_banks(struct platform_device *pdev,
> +				   u32 bank, struct device_node *np)
> +{
> +	struct altera_quadspi *dev = platform_get_drvdata(pdev);
> +	struct mtd_part_parser_data ppdata = {};
> +	struct altera_quadspi_flash *flash;
> +	struct spi_nor *nor;
> +	int ret = 0;
> +	char modalias[40];
> +	const char *flash_name;
> +
> +	altera_quadspi_chip_select(dev, bank);
> +
> +	if (bank > dev->num_flashes - 1)
> +		return -EINVAL;

Not a big deal, but wouldn't it make sense to put the 'bank > ...' check
before the call to altera_quadspi_chip_select()?

> +
> +	flash = devm_kzalloc(&pdev->dev, sizeof(*flash), GFP_KERNEL);
> +	if (!flash)
> +		return -ENOMEM;
> +
> +	dev->flash[bank] = flash;
> +	nor = &flash->nor;
> +	nor->mtd = &flash->mtd;
> +	nor->dev = &pdev->dev;
> +	nor->priv = flash;
> +	flash->mtd.priv = nor;
> +	flash->priv = dev;
> +
> +	/* spi nor framework*/
> +	nor->read_reg = altera_quadspi_read_reg;
> +	nor->write_reg = altera_quadspi_write_reg;
> +	nor->read = altera_quadspi_read;
> +	nor->write = altera_quadspi_write;
> +	nor->erase = altera_quadspi_erase;
> +	nor->flash_lock = altera_quadspi_lock;
> +	nor->flash_unlock = altera_quadspi_unlock;
> +
> +	if (of_modalias_node(np, modalias, sizeof(modalias)) < 0)
> +		return -EINVAL;
> +
> +	flash_name = get_flash_name(nor);
> +	if (flash_name == NULL)
> +		return -EINVAL;
> +
> +	if (strcmp(flash_name, modalias) != 0) {
> +		dev_err(nor->dev,
> +			"flash name %s mismatch with device tree %s\n",
> +			flash_name, modalias);
> +		return -EINVAL;
> +	}
> +	ret = spi_nor_scan(nor, flash_name, SPI_NOR_QUAD);
> +		if (ret)
> +			return ret;
> +
> +	ppdata.of_node = np;
> +
> +	return mtd_device_parse_register(&flash->mtd, NULL, &ppdata, NULL, 0);
> +}
> +
> +static int altera_quadspi_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct altera_quadspi_plat *pdata = NULL;

The NULL assignment is superfluous.

> +	struct altera_quadspi *dev;
> +	int ret = 0;
> +	int i;
> +
> +	if (!np) {
> +		ret = -ENODEV;
> +		dev_err(&pdev->dev, "no device found\n");
> +		goto err;
> +	}
> +
> +	pdata = devm_kzalloc(&pdev->dev,
> +			     sizeof(struct altera_quadspi_plat),
> +			     GFP_KERNEL);

It's not real clear why you're using this pdata struct at all. Are you
planning to support non-DT platform devices, or is this going to be
DT-only? (The check for "if (!np) { ... }" above looks like you're
DT-only.)

But anyway, this pdata struct is only used for the duration of the probe
function, after which it is not used. It's true devm_* will take care of
freeing it eventually, but wouldn't it make more sense to just free it
up when you're done? e.g., put it on the stack instead (local variable)?
Or just remove it entirely, and stash things directly into *dev and
*flash.

> +
> +	if (!pdata) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	ret = altera_quadspi_probe_config_dt(pdev, np, pdata);
> +	if (ret) {
> +		ret = -ENODEV;
> +		dev_err(&pdev->dev, "probe fail\n");
> +		goto err;
> +	}
> +
> +	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
> +	if (!dev) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	dev->is_epcs = pdata->is_epcs;
> +	dev->csr_base = pdata->csr_base;
> +	dev->data_base = pdata->data_base;
> +
> +	/* check number of flashes */
> +	dev->num_flashes = pdata->num_flashes;
> +	if (dev->num_flashes > MAX_NUM_FLASH_CHIP) {
> +		dev_err(&pdev->dev, "exceeding max number of flashes\n");
> +		dev->num_flashes = MAX_NUM_FLASH_CHIP;
> +	}
> +
> +	/* check clock */
> +	dev->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(dev->clk)) {
> +		ret = PTR_ERR(dev->clk);
> +		goto err;
> +	}
> +	ret = clk_prepare_enable(dev->clk);
> +	if (ret)
> +		goto err;
> +
> +	platform_set_drvdata(pdev, dev);
> +
> +	/* loop for each flash which is connected to quadspi */
> +	for (i = 0; i < dev->num_flashes; i++) {
> +		ret = altera_quadspi_setup_banks(pdev, i, pdata->np[i]);
> +		if (ret) {
> +			dev_err(&pdev->dev, "bank setup failed\n");
> +			goto err_bank_setup;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_bank_setup:
> +	clk_disable_unprepare(dev->clk);
> +err:
> +	return ret;
> +}
> +
> +static int altera_quadspi_remove(struct platform_device *pdev)
> +{
> +	struct altera_quadspi *dev;
> +	struct altera_quadspi_flash *flash;
> +	int ret, i;
> +
> +	dev = platform_get_drvdata(pdev);
> +
> +	/* clean up for all nor flash */
> +	for (i = 0; i < dev->num_flashes; i++) {
> +		flash = dev->flash[i];
> +		if (!flash)
> +			continue;
> +
> +		/* clean up mtd stuff */
> +		ret = mtd_device_unregister(&flash->mtd);
> +		if (ret)
> +			dev_err(&pdev->dev, "error removing mtd\n");
> +	}
> +
> +	clk_disable_unprepare(dev->clk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id altera_quadspi_id_table[] = {
> +	{ .compatible = "altr,quadspi-1.0" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, altera_quadspi_id_table);
> +
> +static struct platform_driver altera_quadspi_driver = {
> +	.driver = {
> +		.name = ALTERA_QUADSPI_RESOURCE_NAME,
> +		.bus = &platform_bus_type,

^^ You don't need that line. module_platform_driver() (specifically,
__platform_driver_register()) takes care of this for you.

> +		.of_match_table = altera_quadspi_id_table,
> +	},
> +	.probe = altera_quadspi_probe,
> +	.remove = altera_quadspi_remove,
> +};
> +module_platform_driver(altera_quadspi_driver);
> +
> +MODULE_AUTHOR("Viet Nga Dao <vndao@...era.com>");
> +MODULE_DESCRIPTION("Altera QuadSPI Driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 43bb552..ad0c274 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -683,6 +683,17 @@ static const struct spi_device_id spi_nor_ids[] = {
>  	{ "cat25c09", CAT25_INFO( 128, 8, 32, 2, SPI_NOR_NO_ERASE | SPI_NOR_NO_FR) },
>  	{ "cat25c17", CAT25_INFO( 256, 8, 32, 2, SPI_NOR_NO_ERASE | SPI_NOR_NO_FR) },
>  	{ "cat25128", CAT25_INFO(2048, 8, 64, 2, SPI_NOR_NO_ERASE | SPI_NOR_NO_FR) },
> +
> +	/* Altera EPCQ/EPCS Flashes */
> +	{ "epcq16-nonjedec",  INFO(0, 0, 0x10000, 32,   0) },
> +	{ "epcq32-nonjedec",  INFO(0, 0, 0x10000, 64,   0) },
> +	{ "epcq64-nonjedec",  INFO(0, 0, 0x10000, 128,  0) },
> +	{ "epcq128-nonjedec", INFO(0, 0, 0x10000, 256,  0) },
> +	{ "epcq256-nonjedec", INFO(0, 0, 0x10000, 512,  0) },
> +	{ "epcq512-nonjedec", INFO(0, 0, 0x10000, 1024, 0) },
> +	{ "epcs16-nonjedec",  INFO(0, 0, 0x10000, 32,   0) },
> +	{ "epcs64-nonjedec",  INFO(0, 0, 0x10000, 128,  0) },
> +	{ "epcs128-nonjedec", INFO(0, 0, 0x40000, 256,  0) },

You probably should just drop the "-nonjedec" part. That will help you
have a more sane DT binding. I realize you're imitating the
"m25p80-nonjedec" entries that already exist, but I think those names
exist mostly because there are otherwise-identical version of them that
just don't support the READ ID command. Your parts are unique, and don't
have corresponding JEDEC READ ID compatible versions.

You could still include a comment above them, to note their origin, and
how they don't support many traditional commands.

>  	{ },
>  };
>  

Thanks,
Brian
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