Re: [PATCH linux-next v2 02/14] mtd: spi-nor: properly detect the memory when it boots in Quad or Dual mode

[Boris Brezillon]

Hi Cyrille,

Sorry for this pretty useless review, but I think you know more about
SPI-NOR than I do. So, consider my comments as nitpicks, which shouldn't
prevent your series from being applied.

On Fri, 8 Jan 2016 17:02:14 +0100
Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx> wrote:

> The quad (or dual) mode of a spi-nor memory may be enabled at boot time by
> non-volatile bits in some setting register. Also such a mode may have
> already been enabled at early stage by some boot loader.
> 
> Hence, we should not guess the spi-nor memory is always configured for the
> regular SPI 1-1-1 protocol.
> 
> Micron and Macronix memories, once their Quad (or dual for Micron) mode
> enabled, no longer process the regular JEDEC Read ID (0x9f) command but
> instead reply to a new command: JEDEC Read ID Multiple I/O (0xaf).
> Besides, in Quad mode both memory manufacturers expect ALL commands to
> use the SPI 4-4-4 protocol. For Micron memories, enabling their Dual mode
> implies to use the SPI 2-2-2 protocol for ALL commands.
> 
> Winbond memories, once their Quad mode enabled, expect ALL commands to use
> the SPI 4-4-4 protocol. Unlike Micron and Macronix memories, they still
> reply to the regular JEDEC Read ID (0x9f) command.
> 
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 83 ++++++++++++++++++++++++++++++++++++++++---
>  include/linux/mtd/spi-nor.h   | 50 ++++++++++++++++++++++++--
>  2 files changed, 127 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 3028c06547c1..8967319ea7da 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -73,6 +73,12 @@ struct flash_info {
>  
>  #define JEDEC_MFR(info)	((info)->id[0])
>  
> +struct read_id_config {
> +	enum read_mode		mode;
> +	enum spi_nor_protocol	proto;
> +	u8			opcode;
> +};
> +
>  static const struct flash_info *spi_nor_match_id(const char *name);
>  
>  /*
> @@ -879,11 +885,22 @@ static const struct flash_info spi_nor_ids[] = {
>  	{ },
>  };
>  
> -static const struct flash_info *spi_nor_read_id(struct spi_nor *nor)
> +static const struct flash_info *spi_nor_read_id(struct spi_nor *nor,
> +						enum read_mode mode)
>  {
> -	int			tmp;
> +	int			i, tmp;
>  	u8			id[SPI_NOR_MAX_ID_LEN];
>  	const struct flash_info	*info;
> +	static const struct read_id_config configs[] = {
> +		/* Winbond QPI mode */
> +		{SPI_NOR_QUAD, SNOR_PROTO_4_4_4, SPINOR_OP_RDID},
> +
> +		/* Micron Quad mode & Macronix QPI mode */
> +		{SPI_NOR_QUAD, SNOR_PROTO_4_4_4, SPINOR_OP_MIO_RDID},
> +
> +		/* Micron Dual mode */
> +		{SPI_NOR_DUAL, SNOR_PROTO_2_2_2, SPINOR_OP_MIO_RDID}
> +	};
>  
>  	tmp = nor->read_reg(nor, SPINOR_OP_RDID, id, SPI_NOR_MAX_ID_LEN);
>  	if (tmp < 0) {
> @@ -891,6 +908,58 @@ static const struct flash_info *spi_nor_read_id(struct spi_nor *nor)
>  		return ERR_PTR(tmp);
>  	}
>  
> +	/*
> +	 * Check whether the SPI NOR memory has already been configured (at
> +	 * reset or by some bootloader) to use a protocol other than SPI 1-1-1.
> +	 */
> +	for (i = 0; i < ARRAY_SIZE(configs); ++i) {
> +		int len = SPI_NOR_MAX_ID_LEN;
> +		bool is_multi = false;
> +
> +		/*
> +		 * Check the latest read Manufacturer ID + Device ID (3 bytes):
> +		 * if they are different from both 0x000000 and 0xffffff, we
> +		 * assume that we succeeded in reading a valid JEDEC ID so we
> +		 * don't need to try other SPI protocols.
> +		 * Indeed when either the protocol or the op code are not valid,
> +		 * the SPI NOR memory should not reply to the command. Hence the
> +		 * SPI I/O lines remain in their default state: 1 when connected
> +		 * to pull-up resistors or 0 with pull-down.
> +		 */
> +		if (!((id[0] == 0xff && id[1] == 0xff && id[2] == 0xff) ||
> +		      (id[0] == 0x00 && id[1] == 0x00 && id[2] == 0x00)))
> +			break;

Hopefully, you'll have all the pins configured with pull-up or
pull-down resistors, but what if one of them is configured differently?

Shouldn't we try to find a valid chip definition by iterating over the
spi_nor_ids[] table after each mode change?

> +
> +		/* Only try protocols supported by the user. */
> +		if (configs[i].mode != mode)
> +			continue;
> +
> +		/* Set this protocol for all commands. */
> +		nor->reg_proto = configs[i].proto;
> +		nor->read_proto = configs[i].proto;
> +		nor->write_proto = configs[i].proto;
> +		nor->erase_proto = configs[i].proto;
> +
> +		/*
> +		 * Multiple I/O Read ID only returns the Manufacturer ID
> +		 * (1 byte) and the Device ID (2 bytes). So we reset the
> +		 * remaining bytes.
> +		 */
> +		if (configs[i].opcode == SPINOR_OP_MIO_RDID) {
> +			is_multi = true;
> +			len = 3;
> +			memset(id + len, 0, sizeof(id) - len);
> +		}
> +
> +		tmp = nor->read_reg(nor, configs[i].opcode, id, len);
> +		if (tmp < 0) {
> +			dev_dbg(nor->dev,
> +				"error %d reading JEDEC ID%s\n",
> +				tmp, (is_multi ? " Multi I/O" : ""));
> +			return ERR_PTR(tmp);
> +		}
> +	}
> +
>  	for (tmp = 0; tmp < ARRAY_SIZE(spi_nor_ids) - 1; tmp++) {
>  		info = &spi_nor_ids[tmp];
>  		if (info->id_len) {
> @@ -1148,11 +1217,17 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
>  	if (ret)
>  		return ret;
>  
> +	/* Reset SPI protocol for all commands */
> +	nor->erase_proto = SNOR_PROTO_1_1_1;
> +	nor->read_proto = SNOR_PROTO_1_1_1;
> +	nor->write_proto = SNOR_PROTO_1_1_1;
> +	nor->reg_proto = SNOR_PROTO_1_1_1;
> +
>  	if (name)
>  		info = spi_nor_match_id(name);
>  	/* Try to auto-detect if chip name wasn't specified or not found */
>  	if (!info)
> -		info = spi_nor_read_id(nor);
> +		info = spi_nor_read_id(nor, mode);
>  	if (IS_ERR_OR_NULL(info))
>  		return -ENOENT;
>  
> @@ -1163,7 +1238,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
>  	if (name && info->id_len) {
>  		const struct flash_info *jinfo;
>  
> -		jinfo = spi_nor_read_id(nor);
> +		jinfo = spi_nor_read_id(nor, mode);
>  		if (IS_ERR(jinfo)) {
>  			return PTR_ERR(jinfo);
>  		} else if (jinfo != info) {
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index 62356d50815b..53932c87bcf2 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -75,8 +75,9 @@
>  #define SPINOR_OP_BRWR		0x17	/* Bank register write */
>  
>  /* Used for Micron flashes only. */
> -#define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */
> -#define SPINOR_OP_WD_EVCR      0x61    /* Write EVCR register */
> +#define SPINOR_OP_MIO_RDID	0xaf	/* Multiple I/O Read JEDEC ID */
> +#define SPINOR_OP_RD_EVCR	0x65    /* Read EVCR register */
> +#define SPINOR_OP_WD_EVCR	0x61    /* Write EVCR register */
>  
>  /* Status Register bits. */
>  #define SR_WIP			BIT(0)	/* Write in progress */
> @@ -105,6 +106,43 @@ enum read_mode {
>  	SPI_NOR_QUAD,
>  };
>  
> +

Extra blank line here ^

> +#define SNOR_PROTO_CMD_OFF	8
> +#define SNOR_PROTO_CMD_MASK	GENMASK(11, 8)
> +#define SNOR_PROTO_CMD_TO_PROTO(cmd) \
> +	(((cmd) << SNOR_PROTO_CMD_OFF) & SNOR_PROTO_CMD_MASK)
> +#define SNOR_PROTO_CMD_FROM_PROTO(proto) \
> +	((((u32)(proto)) & SNOR_PROTO_CMD_MASK) >> SNOR_PROTO_CMD_OFF)
> +
> +#define SNOR_PROTO_ADDR_OFF	4
> +#define SNOR_PROTO_ADDR_MASK	GENMASK(7, 4)
> +#define SNOR_PROTO_ADDR_TO_PROTO(addr) \
> +	(((addr) << SNOR_PROTO_ADDR_OFF) & SNOR_PROTO_ADDR_MASK)
> +#define SNOR_PROTO_ADDR_FROM_PROTO(proto) \
> +	((((u32)(proto)) & SNOR_PROTO_ADDR_MASK) >> SNOR_PROTO_ADDR_OFF)
> +
> +#define SNOR_PROTO_DATA_OFF	0
> +#define SNOR_PROTO_DATA_MASK	GENMASK(3, 0)

Why not directly reserving 8 bits per cycle type. Your end result is
stored on a 32 bit integer anyway, and since you'll always have only 3
cycle types (ADDR, CMD and DATA). This way, you'll be ready for
SPI-8-8-8 :-).

> +#define SNOR_PROTO_DATA_TO_PROTO(data) \
> +	(((data) << SNOR_PROTO_DATA_OFF) & SNOR_PROTO_DATA_MASK)
> +#define SNOR_PROTO_DATA_FROM_PROTO(proto) \
> +	((((u32)(proto)) & SNOR_PROTO_DATA_MASK) >> SNOR_PROTO_DATA_OFF)
> +
> +#define SNOR_PROTO(cmd, addr, data)	  \
> +	(SNOR_PROTO_CMD_TO_PROTO(cmd) |   \
> +	 SNOR_PROTO_ADDR_TO_PROTO(addr) | \
> +	 SNOR_PROTO_DATA_TO_PROTO(data))
> +
> +enum spi_nor_protocol {
> +	SNOR_PROTO_1_1_1 = SNOR_PROTO(1, 1, 1),	/* SPI */
> +	SNOR_PROTO_1_1_2 = SNOR_PROTO(1, 1, 2),	/* Dual Output */
> +	SNOR_PROTO_1_1_4 = SNOR_PROTO(1, 1, 4),	/* Quad Output */
> +	SNOR_PROTO_1_2_2 = SNOR_PROTO(1, 2, 2),	/* Dual IO */
> +	SNOR_PROTO_1_4_4 = SNOR_PROTO(1, 4, 4),	/* Quad IO */
> +	SNOR_PROTO_2_2_2 = SNOR_PROTO(2, 2, 2),	/* Dual Command */
> +	SNOR_PROTO_4_4_4 = SNOR_PROTO(4, 4, 4),	/* Quad Command */
> +};

Do you really need this enum definition? I mean, directly using
SNOR_PROTO(X, Y, Z) is just as easy as using the SNOR_PROTO_X_Y_Z enum
definitions, and you won't have to define new ones if spi-nor vendors
decide to support new combinations.

> +
>  #define SPI_NOR_MAX_CMD_SIZE	8
>  enum spi_nor_ops {
>  	SPI_NOR_OPS_READ = 0,
> @@ -132,6 +170,10 @@ enum spi_nor_option_flags {
>   * @flash_read:		the mode of the read
>   * @sst_write_second:	used by the SST write operation
>   * @flags:		flag options for the current SPI-NOR (SNOR_F_*)
> + * @erase_proto:	the SPI protocol used by erase operations
> + * @read_proto:		the SPI protocol used by read operations
> + * @write_proto:	the SPI protocol used by write operations
> + * @reg_proto		the SPI protocol used by read_reg/write_reg operations
>   * @cmd_buf:		used by the write_reg
>   * @prepare:		[OPTIONAL] do some preparations for the
>   *			read/write/erase/lock/unlock operations
> @@ -160,6 +202,10 @@ struct spi_nor {
>  	u8			read_opcode;
>  	u8			read_dummy;
>  	u8			program_opcode;
> +	enum spi_nor_protocol	erase_proto;
> +	enum spi_nor_protocol	read_proto;
> +	enum spi_nor_protocol	write_proto;
> +	enum spi_nor_protocol	reg_proto;

Should be u32 fields if you decide to drop the enum definition.

>  	enum read_mode		flash_read;
>  	bool			sst_write_second;
>  	u32			flags;



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com