[PATCH v6 08/21] mtd: spi-nor-core: Introduce flash-specific fixup hooks

[Pratyush Yadav <p.yadav@ti.com>]

Sometimes the information in a flash's SFDP tables is wrong. Sometimes
some information just can't be expressed in the SFDP table. So,
introduce the fixup hooks to allow tailoring settings for a specific
flash.

Three hooks are added: default_init, post_sfdp, and post_bfpt. These
allow tweaking the flash settings at different point in the probe
sequence. Since the hooks reside in nor->info, set that value just
before the call to spi_nor_init_params().

The hooks and at what points they are executed mimics Linux's spi-nor
framework. One major difference is that Linux puts the struct
spi_nor_fixups in nor->info. This is not possible in U-Boot because the
spi-nor-ids list is shared between spi-nor-core.c and spi-nor-tiny.c.
Since spi-nor-tiny shouldn't have those fixup hooks populated, add a
separate function that lets flashes populate their fixup hooks.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
 drivers/mtd/spi/spi-nor-core.c | 78 ++++++++++++++++++++++++++++++++--
 include/linux/mtd/spi-nor.h    |  2 +
 2 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 28f5f877b4..2494c2e724 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -150,6 +150,31 @@ struct sfdp_bfpt {
 	u32	dwords[BFPT_DWORD_MAX];
 };
 
+/**
+ * struct spi_nor_fixups - SPI NOR fixup hooks
+ * @default_init: called after default flash parameters init. Used to tweak
+ *                flash parameters when information provided by the flash_info
+ *                table is incomplete or wrong.
+ * @post_bfpt: called after the BFPT table has been parsed
+ * @post_sfdp: called after SFDP has been parsed (is also called for SPI NORs
+ *             that do not support RDSFDP). Typically used to tweak various
+ *             parameters that could not be extracted by other means (i.e.
+ *             when information provided by the SFDP/flash_info tables are
+ *             incomplete or wrong).
+ *
+ * Those hooks can be used to tweak the SPI NOR configuration when the SFDP
+ * table is broken or not available.
+ */
+struct spi_nor_fixups {
+	void (*default_init)(struct spi_nor *nor);
+	int (*post_bfpt)(struct spi_nor *nor,
+			 const struct sfdp_parameter_header *bfpt_header,
+			 const struct sfdp_bfpt *bfpt,
+			 struct spi_nor_flash_parameter *params);
+	void (*post_sfdp)(struct spi_nor *nor,
+			  struct spi_nor_flash_parameter *params);
+};
+
 static int spi_nor_read_write_reg(struct spi_nor *nor, struct spi_mem_op
 		*op, void *buf)
 {
@@ -1747,6 +1772,18 @@ static const struct sfdp_bfpt_erase sfdp_bfpt_erases[] = {
 
 static int spi_nor_hwcaps_read2cmd(u32 hwcaps);
 
+static int
+spi_nor_post_bfpt_fixups(struct spi_nor *nor,
+			 const struct sfdp_parameter_header *bfpt_header,
+			 const struct sfdp_bfpt *bfpt,
+			 struct spi_nor_flash_parameter *params)
+{
+	if (nor->fixups && nor->fixups->post_bfpt)
+		return nor->fixups->post_bfpt(nor, bfpt_header, bfpt, params);
+
+	return 0;
+}
+
 /**
  * spi_nor_parse_bfpt() - read and parse the Basic Flash Parameter Table.
  * @nor:		pointer to a 'struct spi_nor'
@@ -1885,7 +1922,8 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 
 	/* Stop here if not JESD216 rev A or later. */
 	if (bfpt_header->length < BFPT_DWORD_MAX)
-		return 0;
+		return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt,
+						params);
 
 	/* Page size: this field specifies 'N' so the page size = 2^N bytes. */
 	params->page_size = bfpt.dwords[BFPT_DWORD(11)];
@@ -1918,7 +1956,7 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 		return -EINVAL;
 	}
 
-	return 0;
+	return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt, params);
 }
 
 /**
@@ -2081,6 +2119,29 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
 }
 #endif /* SPI_FLASH_SFDP_SUPPORT */
 
+/**
+ * spi_nor_post_sfdp_fixups() - Updates the flash's parameters and settings
+ * after SFDP has been parsed (is also called for SPI NORs that do not
+ * support RDSFDP).
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Typically used to tweak various parameters that could not be extracted by
+ * other means (i.e. when information provided by the SFDP/flash_info tables
+ * are incomplete or wrong).
+ */
+static void spi_nor_post_sfdp_fixups(struct spi_nor *nor,
+				     struct spi_nor_flash_parameter *params)
+{
+	if (nor->fixups && nor->fixups->post_sfdp)
+		nor->fixups->post_sfdp(nor, params);
+}
+
+static void spi_nor_default_init_fixups(struct spi_nor *nor)
+{
+	if (nor->fixups && nor->fixups->default_init)
+		nor->fixups->default_init(nor);
+}
+
 static int spi_nor_init_params(struct spi_nor *nor,
 			       const struct flash_info *info,
 			       struct spi_nor_flash_parameter *params)
@@ -2159,6 +2220,8 @@ static int spi_nor_init_params(struct spi_nor *nor,
 		}
 	}
 
+	spi_nor_default_init_fixups(nor);
+
 	/* Override the parameters with data read from SFDP tables. */
 	nor->addr_width = 0;
 	nor->mtd.erasesize = 0;
@@ -2175,6 +2238,8 @@ static int spi_nor_init_params(struct spi_nor *nor,
 		}
 	}
 
+	spi_nor_post_sfdp_fixups(nor, params);
+
 	return 0;
 }
 
@@ -2422,6 +2487,10 @@ static int spi_nor_init(struct spi_nor *nor)
 	return 0;
 }
 
+void spi_nor_set_fixups(struct spi_nor *nor)
+{
+}
+
 int spi_nor_scan(struct spi_nor *nor)
 {
 	struct spi_nor_flash_parameter params;
@@ -2470,6 +2539,10 @@ int spi_nor_scan(struct spi_nor *nor)
 	info = spi_nor_read_id(nor);
 	if (IS_ERR_OR_NULL(info))
 		return -ENOENT;
+	nor->info = info;
+
+	spi_nor_set_fixups(nor);
+
 	/* Parse the Serial Flash Discoverable Parameters table. */
 	ret = spi_nor_init_params(nor, info, &params);
 	if (ret)
@@ -2569,7 +2642,6 @@ int spi_nor_scan(struct spi_nor *nor)
 	}
 
 	/* Send all the required SPI flash commands to initialize device */
-	nor->info = info;
 	ret = spi_nor_init(nor);
 	if (ret)
 		return ret;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 922e795ea6..5842e9d6ee 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -414,6 +414,7 @@ struct flash_info;
  * @write_proto:	the SPI protocol for write operations
  * @reg_proto		the SPI protocol for read_reg/write_reg/erase operations
  * @cmd_buf:		used by the write_reg
+ * @fixups:		flash-specific fixup hooks.
  * @prepare:		[OPTIONAL] do some preparations for the
  *			read/write/erase/lock/unlock operations
  * @unprepare:		[OPTIONAL] do some post work after the
@@ -455,6 +456,7 @@ struct spi_nor {
 	bool			sst_write_second;
 	u32			flags;
 	u8			cmd_buf[SPI_NOR_MAX_CMD_SIZE];
+	struct spi_nor_fixups	*fixups;
 
 	int (*setup)(struct spi_nor *nor, const struct flash_info *info,
 		     const struct spi_nor_flash_parameter *params,
-- 
2.27.0