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[PATCH v4 1/6] mtd: dataflash: Replace C99 types with their kernel counterparts

Started byAndrey Smirnov <andrew.smirnov@gmail.com>
First post2017-04-20 18:40 +0200
Last post2017-04-20 18:40 +0200
Articles 5 — 2 participants

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Contents

  [PATCH v4 1/6] mtd: dataflash: Replace C99 types with their kernel counterparts Andrey Smirnov <andrew.smirnov@gmail.com> - 2017-04-20 18:40 +0200
    [PATCH v4 5/6] mtd: dataflash: Make use of "extened device information" Andrey Smirnov <andrew.smirnov@gmail.com> - 2017-04-20 18:40 +0200
      Re: [PATCH v4 5/6] mtd: dataflash: Make use of "extened device  information" Marek Vasut <marek.vasut@gmail.com> - 2017-04-20 19:30 +0200
    [PATCH v4 2/6] mtd: dataflash: Improve coding style in jedec_probe() Andrey Smirnov <andrew.smirnov@gmail.com> - 2017-04-20 18:40 +0200
    [PATCH v4 4/6] mtd: dataflash: Get rid of loop counter in jedec_probe() Andrey Smirnov <andrew.smirnov@gmail.com> - 2017-04-20 18:40 +0200

#1627668 — [PATCH v4 1/6] mtd: dataflash: Replace C99 types with their kernel counterparts

FromAndrey Smirnov <andrew.smirnov@gmail.com>
Date2017-04-20 18:40 +0200
Subject[PATCH v4 1/6] mtd: dataflash: Replace C99 types with their kernel counterparts
Message-ID<tynhD-2OS-5@gated-at.bofh.it>
No functional change intended.

Cc: cphealy@gmail.com
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Cc: linux-kernel@vger.kernel.org
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

No changes since [v3]


Changes since [v2]:

	- Re-worded commit message

	- Collected Acked-by from Marek

Not present in v1

[v2]: http://lkml.kernel.org/r/20170418142127.23301-1-andrew.smirnov@gmail.com
[v3]: http://lkml.kernel.org/r/20170419152305.17226-1-andrew.smirnov@gmail.com


 drivers/mtd/devices/mtd_dataflash.c | 40 ++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
index f9e9bd1..a566231 100644
--- a/drivers/mtd/devices/mtd_dataflash.c
+++ b/drivers/mtd/devices/mtd_dataflash.c
@@ -84,7 +84,7 @@
 
 
 struct dataflash {
-	uint8_t			command[4];
+	u8			command[4];
 	char			name[24];
 
 	unsigned short		page_offset;	/* offset in flash address */
@@ -153,8 +153,8 @@ static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)
 	struct spi_transfer	x = { };
 	struct spi_message	msg;
 	unsigned		blocksize = priv->page_size << 3;
-	uint8_t			*command;
-	uint32_t		rem;
+	u8			*command;
+	u32			rem;
 
 	pr_debug("%s: erase addr=0x%llx len 0x%llx\n",
 	      dev_name(&spi->dev), (long long)instr->addr,
@@ -187,8 +187,8 @@ static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)
 		pageaddr = pageaddr << priv->page_offset;
 
 		command[0] = do_block ? OP_ERASE_BLOCK : OP_ERASE_PAGE;
-		command[1] = (uint8_t)(pageaddr >> 16);
-		command[2] = (uint8_t)(pageaddr >> 8);
+		command[1] = (u8)(pageaddr >> 16);
+		command[2] = (u8)(pageaddr >> 8);
 		command[3] = 0;
 
 		pr_debug("ERASE %s: (%x) %x %x %x [%i]\n",
@@ -239,7 +239,7 @@ static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,
 	struct spi_transfer	x[2] = { };
 	struct spi_message	msg;
 	unsigned int		addr;
-	uint8_t			*command;
+	u8			*command;
 	int			status;
 
 	pr_debug("%s: read 0x%x..0x%x\n", dev_name(&priv->spi->dev),
@@ -271,9 +271,9 @@ static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,
 	 * fewer "don't care" bytes.  Both buffers stay unchanged.
 	 */
 	command[0] = OP_READ_CONTINUOUS;
-	command[1] = (uint8_t)(addr >> 16);
-	command[2] = (uint8_t)(addr >> 8);
-	command[3] = (uint8_t)(addr >> 0);
+	command[1] = (u8)(addr >> 16);
+	command[2] = (u8)(addr >> 8);
+	command[3] = (u8)(addr >> 0);
 	/* plus 4 "don't care" bytes */
 
 	status = spi_sync(priv->spi, &msg);
@@ -308,7 +308,7 @@ static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
 	size_t			remaining = len;
 	u_char			*writebuf = (u_char *) buf;
 	int			status = -EINVAL;
-	uint8_t			*command;
+	u8			*command;
 
 	pr_debug("%s: write 0x%x..0x%x\n",
 		dev_name(&spi->dev), (unsigned)to, (unsigned)(to + len));
@@ -455,11 +455,11 @@ static int dataflash_get_otp_info(struct mtd_info *mtd, size_t len,
 }
 
 static ssize_t otp_read(struct spi_device *spi, unsigned base,
-		uint8_t *buf, loff_t off, size_t len)
+		u8 *buf, loff_t off, size_t len)
 {
 	struct spi_message	m;
 	size_t			l;
-	uint8_t			*scratch;
+	u8			*scratch;
 	struct spi_transfer	t;
 	int			status;
 
@@ -538,7 +538,7 @@ static int dataflash_write_user_otp(struct mtd_info *mtd,
 {
 	struct spi_message	m;
 	const size_t		l = 4 + 64;
-	uint8_t			*scratch;
+	u8			*scratch;
 	struct spi_transfer	t;
 	struct dataflash	*priv = mtd->priv;
 	int			status;
@@ -689,14 +689,14 @@ struct flash_info {
 	/* JEDEC id has a high byte of zero plus three data bytes:
 	 * the manufacturer id, then a two byte device id.
 	 */
-	uint32_t	jedec_id;
+	u32		jedec_id;
 
 	/* The size listed here is what works with OP_ERASE_PAGE. */
 	unsigned	nr_pages;
-	uint16_t	pagesize;
-	uint16_t	pageoffset;
+	u16		pagesize;
+	u16		pageoffset;
 
-	uint16_t	flags;
+	u16		flags;
 #define SUP_POW2PS	0x0002		/* supports 2^N byte pages */
 #define IS_POW2PS	0x0001		/* uses 2^N byte pages */
 };
@@ -739,9 +739,9 @@ static struct flash_info dataflash_data[] = {
 static struct flash_info *jedec_probe(struct spi_device *spi)
 {
 	int			tmp;
-	uint8_t			code = OP_READ_ID;
-	uint8_t			id[3];
-	uint32_t		jedec;
+	u8			code = OP_READ_ID;
+	u8			id[3];
+	u32			jedec;
 	struct flash_info	*info;
 	int status;
 
-- 
2.9.3

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#1627671 — [PATCH v4 5/6] mtd: dataflash: Make use of "extened device information"

FromAndrey Smirnov <andrew.smirnov@gmail.com>
Date2017-04-20 18:40 +0200
Subject[PATCH v4 5/6] mtd: dataflash: Make use of "extened device information"
Message-ID<tynhE-2OS-21@gated-at.bofh.it>
In reply to#1627668
In anticipation of supporting chips that need it, extend the size of
struct flash_info's 'jedec_id' field to make room 2 byte of extended
device information as well as add code to fetch this data during
jedec_probe().

Cc: cphealy@gmail.com
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

Changes since [v3]:

	- Convert patch to use SUP_EXTID flag and avoid patching
          dataflash_data table

Changes since [v2]:

	- Make 'id' have same size as 'jedec'

	- Get rid of eid_mask variable in favour of using GENMASK
          in-place

Changes since [v1]:

	- Formatting

[v1] http://lkml.kernel.org/r/20170411161722.11164-1-andrew.smirnov@gmail.com
[v2] http://lkml.kernel.org/r/20170418142127.23301-3-andrew.smirnov@gmail.com
[v3] http://lkml.kernel.org/r/20170419152305.17226-5-andrew.smirnov@gmail.com

 drivers/mtd/devices/mtd_dataflash.c | 88 ++++++++++++++++++++++++-------------
 1 file changed, 57 insertions(+), 31 deletions(-)

diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
index 2d3e403..9342cc47 100644
--- a/drivers/mtd/devices/mtd_dataflash.c
+++ b/drivers/mtd/devices/mtd_dataflash.c
@@ -84,6 +84,9 @@
 
 #define CFI_MFR_ATMEL		0x1F
 
+#define DATAFLASH_SHIFT_EXTID	24
+#define DATAFLASH_SHIFT_ID	40
+
 struct dataflash {
 	u8			command[4];
 	char			name[24];
@@ -687,7 +690,7 @@ struct flash_info {
 	/* JEDEC id has a high byte of zero plus three data bytes:
 	 * the manufacturer id, then a two byte device id.
 	 */
-	u32		jedec_id;
+	u64		jedec_id;
 
 	/* The size listed here is what works with OP_ERASE_PAGE. */
 	unsigned	nr_pages;
@@ -695,6 +698,7 @@ struct flash_info {
 	u16		pageoffset;
 
 	u16		flags;
+#define SUP_EXTID	BIT(3)
 #define SUP_POW2PS	0x0002		/* supports 2^N byte pages */
 #define IS_POW2PS	0x0001		/* uses 2^N byte pages */
 };
@@ -734,42 +738,18 @@ static struct flash_info dataflash_data[] = {
 	{ "at45db642d",  0x1f2800, 8192, 1024, 10, SUP_POW2PS | IS_POW2PS},
 };
 
-static struct flash_info *jedec_probe(struct spi_device *spi)
+static struct flash_info *jedec_lookup(struct spi_device *spi,
+				       u64 jedec, bool use_extid)
 {
-	int ret;
-	u8 code = OP_READ_ID;
-	u8 id[3];
-	u32 jedec;
 	struct flash_info *info;
 	int status;
 
-	/*
-	 * JEDEC also defines an optional "extended device information"
-	 * string for after vendor-specific data, after the three bytes
-	 * we use here.  Supporting some chips might require using it.
-	 *
-	 * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
-	 * That's not an error; only rev C and newer chips handle it, and
-	 * only Atmel sells these chips.
-	 */
-	ret = spi_write_then_read(spi, &code, 1, id, 3);
-	if (ret < 0) {
-		dev_dbg(&spi->dev, "error %d reading JEDEC ID\n", ret);
-		return ERR_PTR(ret);
-	}
-
-	if (id[0] != CFI_MFR_ATMEL)
-		return NULL;
-
-	jedec = id[0];
-	jedec = jedec << 8;
-	jedec |= id[1];
-	jedec = jedec << 8;
-	jedec |= id[2];
-
 	for (info = dataflash_data;
 	     info < dataflash_data + ARRAY_SIZE(dataflash_data);
 	     info++) {
+		if (use_extid && !(info->flags & SUP_EXTID))
+			continue;
+
 		if (info->jedec_id == jedec) {
 			dev_dbg(&spi->dev, "OTP, sector protect%s\n",
 				(info->flags & SUP_POW2PS) ?
@@ -793,12 +773,58 @@ static struct flash_info *jedec_probe(struct spi_device *spi)
 		}
 	}
 
+	return ERR_PTR(-ENODEV);
+}
+
+static struct flash_info *jedec_probe(struct spi_device *spi)
+{
+	int ret;
+	u8 code = OP_READ_ID;
+	u64 jedec;
+	u8 id[sizeof(jedec)] = {0};
+	const unsigned int id_size = 5;
+	struct flash_info *info;
+
+	/*
+	 * JEDEC also defines an optional "extended device information"
+	 * string for after vendor-specific data, after the three bytes
+	 * we use here.  Supporting some chips might require using it.
+	 *
+	 * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
+	 * That's not an error; only rev C and newer chips handle it, and
+	 * only Atmel sells these chips.
+	 */
+	ret = spi_write_then_read(spi, &code, 1, id, id_size);
+	if (ret < 0) {
+		dev_dbg(&spi->dev, "error %d reading JEDEC ID\n", ret);
+		return ERR_PTR(ret);
+	}
+
+	if (id[0] != CFI_MFR_ATMEL)
+		return NULL;
+
+	jedec = be64_to_cpup((__be64 *)id);
+
+	/*
+	 * First, try to match device using extended device
+	 * information
+	 */
+	info = jedec_lookup(spi, jedec >> DATAFLASH_SHIFT_EXTID, true);
+	if (!IS_ERR(info))
+		return info;
+	/*
+	 * If that fails, make another pass using regular ID
+	 * information
+	 */
+	info = jedec_lookup(spi, jedec >> DATAFLASH_SHIFT_ID, false);
+	if (!IS_ERR(info))
+		return info;
 	/*
 	 * Treat other chips as errors ... we won't know the right page
 	 * size (it might be binary) even when we can tell which density
 	 * class is involved (legacy chip id scheme).
 	 */
-	dev_warn(&spi->dev, "JEDEC id %06x not handled\n", jedec);
+	dev_warn(&spi->dev, "JEDEC id %016llx not handled\n", jedec);
 	return ERR_PTR(-ENODEV);
 }
 
-- 
2.9.3

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#1627698 — Re: [PATCH v4 5/6] mtd: dataflash: Make use of "extened device information"

FromMarek Vasut <marek.vasut@gmail.com>
Date2017-04-20 19:30 +0200
SubjectRe: [PATCH v4 5/6] mtd: dataflash: Make use of "extened device information"
Message-ID<tyo41-3kI-5@gated-at.bofh.it>
In reply to#1627671
On 04/20/2017 06:29 PM, Andrey Smirnov wrote:
> In anticipation of supporting chips that need it, extend the size of
> struct flash_info's 'jedec_id' field to make room 2 byte of extended
> device information as well as add code to fetch this data during
> jedec_probe().
> 
> Cc: cphealy@gmail.com
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Brian Norris <computersforpeace@gmail.com>
> Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
> Cc: Marek Vasut <marek.vasut@gmail.com>
> Cc: Richard Weinberger <richard@nod.at>
> Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
> 
> Changes since [v3]:
> 
> 	- Convert patch to use SUP_EXTID flag and avoid patching
>           dataflash_data table
> 
> Changes since [v2]:
> 
> 	- Make 'id' have same size as 'jedec'
> 
> 	- Get rid of eid_mask variable in favour of using GENMASK
>           in-place
> 
> Changes since [v1]:
> 
> 	- Formatting
> 
> [v1] http://lkml.kernel.org/r/20170411161722.11164-1-andrew.smirnov@gmail.com
> [v2] http://lkml.kernel.org/r/20170418142127.23301-3-andrew.smirnov@gmail.com
> [v3] http://lkml.kernel.org/r/20170419152305.17226-5-andrew.smirnov@gmail.com
> 
>  drivers/mtd/devices/mtd_dataflash.c | 88 ++++++++++++++++++++++++-------------
>  1 file changed, 57 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
> index 2d3e403..9342cc47 100644
> --- a/drivers/mtd/devices/mtd_dataflash.c
> +++ b/drivers/mtd/devices/mtd_dataflash.c
> @@ -84,6 +84,9 @@
>  
>  #define CFI_MFR_ATMEL		0x1F
>  
> +#define DATAFLASH_SHIFT_EXTID	24
> +#define DATAFLASH_SHIFT_ID	40
> +
>  struct dataflash {
>  	u8			command[4];
>  	char			name[24];
> @@ -687,7 +690,7 @@ struct flash_info {
>  	/* JEDEC id has a high byte of zero plus three data bytes:
>  	 * the manufacturer id, then a two byte device id.
>  	 */
> -	u32		jedec_id;
> +	u64		jedec_id;
>  
>  	/* The size listed here is what works with OP_ERASE_PAGE. */
>  	unsigned	nr_pages;
> @@ -695,6 +698,7 @@ struct flash_info {
>  	u16		pageoffset;
>  
>  	u16		flags;
> +#define SUP_EXTID	BIT(3)

Two nits, can we keep things consistent please ? In this case, 0x0004 .
Also, you wanted to use BIT(2)=0x4 here, not BIT(3)=0x8 .

Other than that,
Acked-by: Marek Vasut <marek.vasut@gmail.com>

>  #define SUP_POW2PS	0x0002		/* supports 2^N byte pages */
>  #define IS_POW2PS	0x0001		/* uses 2^N byte pages */
>  };
> @@ -734,42 +738,18 @@ static struct flash_info dataflash_data[] = {
>  	{ "at45db642d",  0x1f2800, 8192, 1024, 10, SUP_POW2PS | IS_POW2PS},
>  };
>  
> -static struct flash_info *jedec_probe(struct spi_device *spi)
> +static struct flash_info *jedec_lookup(struct spi_device *spi,
> +				       u64 jedec, bool use_extid)
>  {
> -	int ret;
> -	u8 code = OP_READ_ID;
> -	u8 id[3];
> -	u32 jedec;
>  	struct flash_info *info;
>  	int status;
>  
> -	/*
> -	 * JEDEC also defines an optional "extended device information"
> -	 * string for after vendor-specific data, after the three bytes
> -	 * we use here.  Supporting some chips might require using it.
> -	 *
> -	 * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
> -	 * That's not an error; only rev C and newer chips handle it, and
> -	 * only Atmel sells these chips.
> -	 */
> -	ret = spi_write_then_read(spi, &code, 1, id, 3);
> -	if (ret < 0) {
> -		dev_dbg(&spi->dev, "error %d reading JEDEC ID\n", ret);
> -		return ERR_PTR(ret);
> -	}
> -
> -	if (id[0] != CFI_MFR_ATMEL)
> -		return NULL;
> -
> -	jedec = id[0];
> -	jedec = jedec << 8;
> -	jedec |= id[1];
> -	jedec = jedec << 8;
> -	jedec |= id[2];
> -
>  	for (info = dataflash_data;
>  	     info < dataflash_data + ARRAY_SIZE(dataflash_data);
>  	     info++) {
> +		if (use_extid && !(info->flags & SUP_EXTID))
> +			continue;
> +
>  		if (info->jedec_id == jedec) {
>  			dev_dbg(&spi->dev, "OTP, sector protect%s\n",
>  				(info->flags & SUP_POW2PS) ?
> @@ -793,12 +773,58 @@ static struct flash_info *jedec_probe(struct spi_device *spi)
>  		}
>  	}
>  
> +	return ERR_PTR(-ENODEV);
> +}
> +
> +static struct flash_info *jedec_probe(struct spi_device *spi)
> +{
> +	int ret;
> +	u8 code = OP_READ_ID;
> +	u64 jedec;
> +	u8 id[sizeof(jedec)] = {0};
> +	const unsigned int id_size = 5;
> +	struct flash_info *info;
> +
> +	/*
> +	 * JEDEC also defines an optional "extended device information"
> +	 * string for after vendor-specific data, after the three bytes
> +	 * we use here.  Supporting some chips might require using it.
> +	 *
> +	 * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
> +	 * That's not an error; only rev C and newer chips handle it, and
> +	 * only Atmel sells these chips.
> +	 */
> +	ret = spi_write_then_read(spi, &code, 1, id, id_size);
> +	if (ret < 0) {
> +		dev_dbg(&spi->dev, "error %d reading JEDEC ID\n", ret);
> +		return ERR_PTR(ret);
> +	}
> +
> +	if (id[0] != CFI_MFR_ATMEL)
> +		return NULL;
> +
> +	jedec = be64_to_cpup((__be64 *)id);
> +
> +	/*
> +	 * First, try to match device using extended device
> +	 * information
> +	 */
> +	info = jedec_lookup(spi, jedec >> DATAFLASH_SHIFT_EXTID, true);
> +	if (!IS_ERR(info))
> +		return info;
> +	/*
> +	 * If that fails, make another pass using regular ID
> +	 * information
> +	 */
> +	info = jedec_lookup(spi, jedec >> DATAFLASH_SHIFT_ID, false);
> +	if (!IS_ERR(info))
> +		return info;
>  	/*
>  	 * Treat other chips as errors ... we won't know the right page
>  	 * size (it might be binary) even when we can tell which density
>  	 * class is involved (legacy chip id scheme).
>  	 */
> -	dev_warn(&spi->dev, "JEDEC id %06x not handled\n", jedec);
> +	dev_warn(&spi->dev, "JEDEC id %016llx not handled\n", jedec);
>  	return ERR_PTR(-ENODEV);
>  }
>  
> 


-- 
Best regards,
Marek Vasut

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#1627672 — [PATCH v4 2/6] mtd: dataflash: Improve coding style in jedec_probe()

FromAndrey Smirnov <andrew.smirnov@gmail.com>
Date2017-04-20 18:40 +0200
Subject[PATCH v4 2/6] mtd: dataflash: Improve coding style in jedec_probe()
Message-ID<tynhE-2OS-25@gated-at.bofh.it>
In reply to#1627668
Change the following:

   - Replace indentation between type and name of local variable from
     tabs to spaces

   - Replace magic number 0x1F with CFI_MFR_ATMEL macro

   - Replace variable 'tmp' with 'ret' and 'i' where appropriate

   - Reformat multi-line comments and add newlines where appropriate

No functional change intended.

Cc: cphealy@gmail.com
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: linux-kernel@vger.kernel.org
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

No changes since [v3]

Changes since [v2]:

	- Re-worded commit message

	- Collected Acked-by from Marek

Not present in v1

[v2] http://lkml.kernel.org/r/20170418142127.23301-2-andrew.smirnov@gmail.com
[v3] http://lkml.kernel.org/r/20170419152305.17226-2-andrew.smirnov@gmail.com

 drivers/mtd/devices/mtd_dataflash.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
index a566231..5b7a8c3 100644
--- a/drivers/mtd/devices/mtd_dataflash.c
+++ b/drivers/mtd/devices/mtd_dataflash.c
@@ -82,6 +82,7 @@
 #define OP_WRITE_SECURITY_REVC	0x9A
 #define OP_WRITE_SECURITY	0x9B	/* revision D */
 
+#define CFI_MFR_ATMEL		0x1F
 
 struct dataflash {
 	u8			command[4];
@@ -738,14 +739,15 @@ static struct flash_info dataflash_data[] = {
 
 static struct flash_info *jedec_probe(struct spi_device *spi)
 {
-	int			tmp;
-	u8			code = OP_READ_ID;
-	u8			id[3];
-	u32			jedec;
-	struct flash_info	*info;
+	int ret, i;
+	u8 code = OP_READ_ID;
+	u8 id[3];
+	u32 jedec;
+	struct flash_info *info;
 	int status;
 
-	/* JEDEC also defines an optional "extended device information"
+	/*
+	 * JEDEC also defines an optional "extended device information"
 	 * string for after vendor-specific data, after the three bytes
 	 * we use here.  Supporting some chips might require using it.
 	 *
@@ -753,13 +755,14 @@ static struct flash_info *jedec_probe(struct spi_device *spi)
 	 * That's not an error; only rev C and newer chips handle it, and
 	 * only Atmel sells these chips.
 	 */
-	tmp = spi_write_then_read(spi, &code, 1, id, 3);
-	if (tmp < 0) {
+	ret = spi_write_then_read(spi, &code, 1, id, 3);
+	if (ret < 0) {
 		pr_debug("%s: error %d reading JEDEC ID\n",
-			dev_name(&spi->dev), tmp);
-		return ERR_PTR(tmp);
+			dev_name(&spi->dev), ret);
+		return ERR_PTR(ret);
 	}
-	if (id[0] != 0x1f)
+
+	if (id[0] != CFI_MFR_ATMEL)
 		return NULL;
 
 	jedec = id[0];
@@ -768,9 +771,9 @@ static struct flash_info *jedec_probe(struct spi_device *spi)
 	jedec = jedec << 8;
 	jedec |= id[2];
 
-	for (tmp = 0, info = dataflash_data;
-			tmp < ARRAY_SIZE(dataflash_data);
-			tmp++, info++) {
+	for (i = 0, info = dataflash_data;
+			i < ARRAY_SIZE(dataflash_data);
+			i++, info++) {
 		if (info->jedec_id == jedec) {
 			pr_debug("%s: OTP, sector protect%s\n",
 				dev_name(&spi->dev),
-- 
2.9.3

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#1627676 — [PATCH v4 4/6] mtd: dataflash: Get rid of loop counter in jedec_probe()

FromAndrey Smirnov <andrew.smirnov@gmail.com>
Date2017-04-20 18:40 +0200
Subject[PATCH v4 4/6] mtd: dataflash: Get rid of loop counter in jedec_probe()
Message-ID<tynhF-2OS-39@gated-at.bofh.it>
In reply to#1627668
"For" loop in jedec_probe can be simplified to not need counter
'i'. Convert the code and get rid of the variable.

Cc: cphealy@gmail.com
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

Changes since [v3]

	- Collected Reviewed-by from Marek

Not present in v2, v1

[v3] http://lkml.kernel.org/r/20170419152305.17226-4-andrew.smirnov@gmail.com

 drivers/mtd/devices/mtd_dataflash.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
index ccd1e02..2d3e403 100644
--- a/drivers/mtd/devices/mtd_dataflash.c
+++ b/drivers/mtd/devices/mtd_dataflash.c
@@ -736,7 +736,7 @@ static struct flash_info dataflash_data[] = {
 
 static struct flash_info *jedec_probe(struct spi_device *spi)
 {
-	int ret, i;
+	int ret;
 	u8 code = OP_READ_ID;
 	u8 id[3];
 	u32 jedec;
@@ -767,9 +767,9 @@ static struct flash_info *jedec_probe(struct spi_device *spi)
 	jedec = jedec << 8;
 	jedec |= id[2];
 
-	for (i = 0, info = dataflash_data;
-			i < ARRAY_SIZE(dataflash_data);
-			i++, info++) {
+	for (info = dataflash_data;
+	     info < dataflash_data + ARRAY_SIZE(dataflash_data);
+	     info++) {
 		if (info->jedec_id == jedec) {
 			dev_dbg(&spi->dev, "OTP, sector protect%s\n",
 				(info->flags & SUP_POW2PS) ?
-- 
2.9.3

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