mtd: spi-nor: sfdp: save a copy of the SFDP data

Due to possible mode switching to 8D-8D-8D, it might not be possible to
read the SFDP after the initial probe. To be able to dump the SFDP via
sysfs afterwards, make a complete copy of it.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Tested-by: Heiko Thiery <heiko.thiery@gmail.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>

diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 9398a87..f6dc280 100644 (file)
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -461,6 +461,16 @@ struct spi_nor_manufacturer {
        const struct spi_nor_fixups *fixups;
 };
 
+/**
+ * struct sfdp - SFDP data
+ * @num_dwords: number of entries in the dwords array
+ * @dwords: array of double words of the SFDP data
+ */
+struct sfdp {
+       size_t  num_dwords;
+       u32     *dwords;
+};
+
 /* Manufacturer drivers. */
 extern const struct spi_nor_manufacturer spi_nor_atmel;
 extern const struct spi_nor_manufacturer spi_nor_catalyst;

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index 23c28e9..c500c21 100644 (file)
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -16,6 +16,7 @@
        (((p)->parameter_table_pointer[2] << 16) | \
         ((p)->parameter_table_pointer[1] <<  8) | \
         ((p)->parameter_table_pointer[0] <<  0))
+#define SFDP_PARAM_HEADER_PARAM_LEN(p) ((p)->length * 4)
 
 #define SFDP_BFPT_ID           0xff00  /* Basic Flash Parameter Table */
 #define SFDP_SECTOR_MAP_ID     0xff81  /* Sector Map Table */
@@ -1245,6 +1246,8 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
        struct sfdp_parameter_header *param_headers = NULL;
        struct sfdp_header header;
        struct device *dev = nor->dev;
+       struct sfdp *sfdp;
+       size_t sfdp_size;
        size_t psize;
        int i, err;
 
@@ -1267,6 +1270,9 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
            bfpt_header->major != SFDP_JESD216_MAJOR)
                return -EINVAL;
 
+       sfdp_size = SFDP_PARAM_HEADER_PTP(bfpt_header) +
+                   SFDP_PARAM_HEADER_PARAM_LEN(bfpt_header);
+
        /*
         * Allocate memory then read all parameter headers with a single
         * Read SFDP command. These parameter headers will actually be parsed
@@ -1294,6 +1300,58 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
        }
 
        /*
+        * Cache the complete SFDP data. It is not (easily) possible to fetch
+        * SFDP after probe time and we need it for the sysfs access.
+        */
+       for (i = 0; i < header.nph; i++) {
+               param_header = &param_headers[i];
+               sfdp_size = max_t(size_t, sfdp_size,
+                                 SFDP_PARAM_HEADER_PTP(param_header) +
+                                 SFDP_PARAM_HEADER_PARAM_LEN(param_header));
+       }
+
+       /*
+        * Limit the total size to a reasonable value to avoid allocating too
+        * much memory just of because the flash returned some insane values.
+        */
+       if (sfdp_size > PAGE_SIZE) {
+               dev_dbg(dev, "SFDP data (%zu) too big, truncating\n",
+                       sfdp_size);
+               sfdp_size = PAGE_SIZE;
+       }
+
+       sfdp = devm_kzalloc(dev, sizeof(*sfdp), GFP_KERNEL);
+       if (!sfdp) {
+               err = -ENOMEM;
+               goto exit;
+       }
+
+       /*
+        * The SFDP is organized in chunks of DWORDs. Thus, in theory, the
+        * sfdp_size should be a multiple of DWORDs. But in case a flash
+        * is not spec compliant, make sure that we have enough space to store
+        * the complete SFDP data.
+        */
+       sfdp->num_dwords = DIV_ROUND_UP(sfdp_size, sizeof(*sfdp->dwords));
+       sfdp->dwords = devm_kcalloc(dev, sfdp->num_dwords,
+                                   sizeof(*sfdp->dwords), GFP_KERNEL);
+       if (!sfdp->dwords) {
+               err = -ENOMEM;
+               devm_kfree(dev, sfdp);
+               goto exit;
+       }
+
+       err = spi_nor_read_sfdp(nor, 0, sfdp_size, sfdp->dwords);
+       if (err < 0) {
+               dev_dbg(dev, "failed to read SFDP data\n");
+               devm_kfree(dev, sfdp->dwords);
+               devm_kfree(dev, sfdp);
+               goto exit;
+       }
+
+       nor->sfdp = sfdp;
+
+       /*
         * Check other parameter headers to get the latest revision of
         * the basic flash parameter table.
         */

diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 98ed91b..f674577 100644 (file)
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -383,6 +383,7 @@ struct spi_nor_flash_parameter;
  * @read_proto:                the SPI protocol for read operations
  * @write_proto:       the SPI protocol for write operations
  * @reg_proto:         the SPI protocol for read_reg/write_reg/erase operations
+ * @sfdp:              the SFDP data of the flash
  * @controller_ops:    SPI NOR controller driver specific operations.
  * @params:            [FLASH-SPECIFIC] SPI NOR flash parameters and settings.
  *                      The structure includes legacy flash parameters and
@@ -412,6 +413,7 @@ struct spi_nor {
        bool                    sst_write_second;
        u32                     flags;
        enum spi_nor_cmd_ext    cmd_ext_type;
+       struct sfdp             *sfdp;
 
        const struct spi_nor_controller_ops *controller_ops;