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

From: Cyrille Pitchen
Date: Mon Jan 11 2016 - 08:56:38 EST

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In reply to: Boris Brezillon: "Re: [PATCH linux-next v2 02/14] mtd: spi-nor: properly detect the memory when it boots in Quad or Dual mode"
Next in thread: Cyrille Pitchen: "[PATCH linux-next v2 03/14] mtd: spi-nor: select op codes and SPI NOR protocols by manufacturer"
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Hi Boris,

Le 11/01/2016 11:08, Boris Brezillon a écrit :
> 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?
>

Honestly I don't know and I didn't test what would happen if no resistors were
used. So maybe you're right, it would be safer to look in the ID table up after
every read attempt.
>> +
>> + /* 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 :-).
>

I've reserved 4 bits per cycle type so the possible values range into [0 - 15].
I thought it would be enough to anticipate future evolution like SPI 8-8-8.
Also it leaves more bits available for future usage.
Finally, I've chosen 4 bits and this order so when debugging and/or printing
the value in hex format, you can easily decode the corresponding protocol:

SPI 1-1-4 -> 0x00000114
SPI 1-2-2 -> 0x00000122
SPI 4-4-4 -> 0x00000444

Anyway I don't mind using 8 bits instead if it is preferred.

>> +#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.
>

This enum was created only for stronger type checking; Except for that, there
is no strong reason to keep the enum. So I don't mind removing it if other
people agree with you.

>> +
>> #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;
>
>
>

Thanks for your review :)

Best regards,

Cyrille

Next message: Wang Nan: "[PATCH 31/53] perf tools: Add perf_data_file__switch() helper"
Previous message: Mathias Nyman: "Re: [RESEND PATCH v2] usb: xhci-mtk: fix AHB bus hang up caused by roothubs polling"
In reply to: Boris Brezillon: "Re: [PATCH linux-next v2 02/14] mtd: spi-nor: properly detect the memory when it boots in Quad or Dual mode"
Next in thread: Cyrille Pitchen: "[PATCH linux-next v2 03/14] mtd: spi-nor: select op codes and SPI NOR protocols by manufacturer"
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