Re: [PATCH v16 05/15] mtd: spi-nor: sfdp: parse xSPI Profile 1.0 table

From: Tudor.Ambarus
Date: Tue Oct 27 2020 - 05:58:44 EST

On 10/5/20 6:31 PM, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> This table is indication that the flash is xSPI compliant and hence
> supports octal DTR mode. Extract information like the fast read opcode,
> dummy cycles, the number of dummy cycles needed for a Read Status
> Register command, and the number of address bytes needed for a Read
> Status Register command.
>
> We don't know what speed the controller is running at. Find the fast
> read dummy cycles for the fastest frequency the flash can run at to be
> sure we are never short of dummy cycles. If nothing is available,
> default to 20. Flashes that use a different value should update it in
> their fixup hooks.
>
> Since we want to set read settings, expose spi_nor_set_read_settings()
> in core.h.
>
> Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
> Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
> ---
> drivers/mtd/spi-nor/core.c | 2 +-
> drivers/mtd/spi-nor/core.h | 10 +++++
> drivers/mtd/spi-nor/sfdp.c | 91 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 102 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 779e64974fea..ad280874a2e8 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2332,7 +2332,7 @@ static int spi_nor_check(struct spi_nor *nor)
> return 0;
> }
>
> -static void
> +void
> spi_nor_set_read_settings(struct spi_nor_read_command *read,
> u8 num_mode_clocks,
> u8 num_wait_states,
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 5d95b4183a33..9a33c8d07335 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -192,6 +192,9 @@ struct spi_nor_locking_ops {
> *
> * @size: the flash memory density in bytes.
> * @page_size: the page size of the SPI NOR flash memory.
> + * @rdsr_dummy: dummy cycles needed for Read Status Register command.
> + * @rdsr_addr_nbytes: dummy address bytes needed for Read Status Register
> + * command.
> * @hwcaps: describes the read and page program hardware
> * capabilities.
> * @reads: read capabilities ordered by priority: the higher index
> @@ -214,6 +217,8 @@ struct spi_nor_locking_ops {
> struct spi_nor_flash_parameter {
> u64 size;
> u32 page_size;
> + u8 rdsr_dummy;
> + u8 rdsr_addr_nbytes;
>
> struct spi_nor_hwcaps hwcaps;
> struct spi_nor_read_command reads[SNOR_CMD_READ_MAX];
> @@ -425,6 +430,11 @@ ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
>
> int spi_nor_hwcaps_read2cmd(u32 hwcaps);
> u8 spi_nor_convert_3to4_read(u8 opcode);
> +void spi_nor_set_read_settings(struct spi_nor_read_command *read,
> + u8 num_mode_clocks,
> + u8 num_wait_states,
> + u8 opcode,
> + enum spi_nor_protocol proto);
> void spi_nor_set_pp_settings(struct spi_nor_pp_command *pp, u8 opcode,
> enum spi_nor_protocol proto);
>
> diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
> index c77655968f80..b2d097b44a55 100644
> --- a/drivers/mtd/spi-nor/sfdp.c
> +++ b/drivers/mtd/spi-nor/sfdp.c
> @@ -4,6 +4,7 @@
> * Copyright (C) 2014, Freescale Semiconductor, Inc.
> */
>
> +#include <linux/bitfield.h>
> #include <linux/slab.h>
> #include <linux/sort.h>
> #include <linux/mtd/spi-nor.h>
> @@ -19,6 +20,7 @@
> #define SFDP_BFPT_ID 0xff00 /* Basic Flash Parameter Table */
> #define SFDP_SECTOR_MAP_ID 0xff81 /* Sector Map Table */
> #define SFDP_4BAIT_ID 0xff84 /* 4-byte Address Instruction Table */
> +#define SFDP_PROFILE1_ID 0xff05 /* xSPI Profile 1.0 table. */
>
> #define SFDP_SIGNATURE 0x50444653U
>
> @@ -1108,6 +1110,91 @@ static int spi_nor_parse_4bait(struct spi_nor *nor,
> return ret;
> }
>
> +#define PROFILE1_DWORD1_RDSR_ADDR_BYTES BIT(29)
> +#define PROFILE1_DWORD1_RDSR_DUMMY BIT(28)
> +#define PROFILE1_DWORD1_RD_FAST_CMD GENMASK(15, 8)
> +#define PROFILE1_DWORD4_DUMMY_200MHZ GENMASK(11, 7)
> +#define PROFILE1_DWORD5_DUMMY_166MHZ GENMASK(31, 27)
> +#define PROFILE1_DWORD5_DUMMY_133MHZ GENMASK(21, 17)
> +#define PROFILE1_DWORD5_DUMMY_100MHZ GENMASK(11, 7)
> +
> +/**
> + * spi_nor_parse_profile1() - parse the xSPI Profile 1.0 table
> + * @nor: pointer to a 'struct spi_nor'
> + * @profile1_header: pointer to the 'struct sfdp_parameter_header' describing
> + * the Profile 1.0 Table length and version.
> + * @params: pointer to the 'struct spi_nor_flash_parameter' to be.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_parse_profile1(struct spi_nor *nor,
> + const struct sfdp_parameter_header *profile1_header,
> + struct spi_nor_flash_parameter *params)
> +{
> + u32 *dwords, addr;
> + size_t len;
> + int ret;
> + u8 dummy, opcode;
> +
> + len = profile1_header->length * sizeof(*dwords);
> + dwords = kmalloc(len, GFP_KERNEL);
> + if (!dwords)
> + return -ENOMEM;
> +
> + addr = SFDP_PARAM_HEADER_PTP(profile1_header);
> + ret = spi_nor_read_sfdp(nor, addr, len, dwords);
> + if (ret)
> + goto out;
> +
> + le32_to_cpu_array(dwords, profile1_header->length);
> +
> + /* Get 8D-8D-8D fast read opcode and dummy cycles. */
> + opcode = FIELD_GET(PROFILE1_DWORD1_RD_FAST_CMD, dwords[0]);
> +
> + /* Set the Read Status Register dummy cycles and dummy address bytes. */
> + if (dwords[0] & PROFILE1_DWORD1_RDSR_DUMMY)
> + params->rdsr_dummy = 8;
> + else
> + params->rdsr_dummy = 4;
> +
> + if (dwords[0] & PROFILE1_DWORD1_RDSR_ADDR_BYTES)
> + params->rdsr_addr_nbytes = 4;
> + else
> + params->rdsr_addr_nbytes = 0;
> +
> + /*
> + * We don't know what speed the controller is running at. Find the
> + * dummy cycles for the fastest frequency the flash can run at to be
> + * sure we are never short of dummy cycles. A value of 0 means the
> + * frequency is not supported.
> + *
> + * Default to PROFILE1_DUMMY_DEFAULT if we don't find anything, and let
> + * flashes set the correct value if needed in their fixup hooks.

We need to update the comment because we got rid of the PROFILE1_DUMMY_DEFAULT,
(which is fine). Operations faster than 200MHz are not part of the current xSPI Spec.
BFPT defines in DWORD20 the maximum operation speed of device in 8D-8D-8D mode, but
does not specify the number of dummy cycles required. Set dummy to zero and let the
manufacturer drivers set the required number of dummy cycles in a fixup hook.

> + */
> + dummy = FIELD_GET(PROFILE1_DWORD4_DUMMY_200MHZ, dwords[3]);
> + if (!dummy)
> + dummy = FIELD_GET(PROFILE1_DWORD5_DUMMY_166MHZ, dwords[4]);
> + if (!dummy)
> + dummy = FIELD_GET(PROFILE1_DWORD5_DUMMY_133MHZ, dwords[4]);
> + if (!dummy)
> + dummy = FIELD_GET(PROFILE1_DWORD5_DUMMY_100MHZ, dwords[4]);
> + if (!dummy)
> + dev_dbg(nor->dev,
> + "Can't find dummy cycles from Profile 1.0 table\n");
> +
> + /* Round up to an even value to avoid tripping controllers up. */
> + dummy = round_up(dummy, 2);
> +
> + /* Update the fast read settings. */
> + spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_8_8_8_DTR],
> + 0, dummy, opcode,
> + SNOR_PROTO_8_8_8_DTR);
> +
> +out:
> + kfree(dwords);
> + return ret;
> +}
> +
> /**
> * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
> * @nor: pointer to a 'struct spi_nor'
> @@ -1209,6 +1296,10 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
> err = spi_nor_parse_4bait(nor, param_header, params);
> break;
>
> + case SFDP_PROFILE1_ID:
> + err = spi_nor_parse_profile1(nor, param_header, params);
> + break;
> +
> default:
> break;
> }
> --
> 2.28.0
>