[PATCH v9 18/28] mtd: spi-nor-core: Parse xSPI Profile 1.0 table

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

This table is indication that the flash is xSPI compliant and hence
supports octal DTR mode. Extract information like the fast read opcode,
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.

The default dummy cycles for a fast octal DTR read are set to 20. Since
there is no simple way of determining the dummy cycles needed for the
fast read command, flashes that use a different value should update it
in their flash-specific hooks.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
 drivers/mtd/spi/spi-nor-core.c | 100 +++++++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h    |   7 +++
 2 files changed, 107 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 7704a62d62..f2327ebd4c 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -21,6 +21,7 @@
 #include <linux/log2.h>
 #include <linux/math64.h>
 #include <linux/sizes.h>
+#include <linux/bitfield.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/spi-nor.h>
@@ -40,6 +41,8 @@
 
 #define DEFAULT_READY_WAIT_JIFFIES		(40UL * HZ)
 
+#define ROUND_UP_TO(x, y)	(((x) + (y) - 1) / (y) * (y))
+
 struct sfdp_parameter_header {
 	u8		id_lsb;
 	u8		minor;
@@ -58,6 +61,7 @@ struct sfdp_parameter_header {
 #define SFDP_BFPT_ID		0xff00	/* Basic Flash Parameter Table */
 #define SFDP_SECTOR_MAP_ID	0xff81	/* Sector Map Table */
 #define SFDP_SST_ID		0x01bf	/* Manufacturer specific Table */
+#define SFDP_PROFILE1_ID	0xff05	/* xSPI Profile 1.0 Table */
 
 #define SFDP_SIGNATURE		0x50444653U
 #define SFDP_JESD216_MAJOR	1
@@ -155,6 +159,16 @@ struct sfdp_header {
 #define BFPT_DWORD18_CMD_EXT_RES		(0x2UL << 29) /* Reserved */
 #define BFPT_DWORD18_CMD_EXT_16B		(0x3UL << 29) /* 16-bit opcode */
 
+/* xSPI Profile 1.0 table (from JESD216D.01). */
+#define PROFILE1_DWORD1_RD_FAST_CMD		GENMASK(15, 8)
+#define PROFILE1_DWORD1_RDSR_DUMMY		BIT(28)
+#define PROFILE1_DWORD1_RDSR_ADDR_BYTES		BIT(29)
+#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)
+#define PROFILE1_DUMMY_DEFAULT			20
+
 struct sfdp_bfpt {
 	u32	dwords[BFPT_DWORD_MAX];
 };
@@ -2095,6 +2109,86 @@ spi_nor_parse_microchip_sfdp(struct spi_nor *nor,
 	return ret;
 }
 
+/**
+ * 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 4-Byte Address Instruction 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 *table, opcode, addr;
+	size_t len;
+	int ret, i;
+	u8 dummy;
+
+	len = profile1_header->length * sizeof(*table);
+	table = kmalloc(len, GFP_KERNEL);
+	if (!table)
+		return -ENOMEM;
+
+	addr = SFDP_PARAM_HEADER_PTP(profile1_header);
+	ret = spi_nor_read_sfdp(nor, addr, len, table);
+	if (ret)
+		goto out;
+
+	/* Fix endianness of the table DWORDs. */
+	for (i = 0; i < profile1_header->length; i++)
+		table[i] = le32_to_cpu(table[i]);
+
+	/* Get 8D-8D-8D fast read opcode and dummy cycles. */
+	opcode = FIELD_GET(PROFILE1_DWORD1_RD_FAST_CMD, table[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.
+	 */
+	dummy = FIELD_GET(PROFILE1_DWORD4_DUMMY_200MHZ, table[3]);
+	if (!dummy)
+		dummy = FIELD_GET(PROFILE1_DWORD5_DUMMY_166MHZ, table[4]);
+	if (!dummy)
+		dummy = FIELD_GET(PROFILE1_DWORD5_DUMMY_133MHZ, table[4]);
+	if (!dummy)
+		dummy = FIELD_GET(PROFILE1_DWORD5_DUMMY_100MHZ, table[4]);
+	if (!dummy)
+		dummy = PROFILE1_DUMMY_DEFAULT;
+
+	/* Round up to an even value to avoid tripping controllers up. */
+	dummy = ROUND_UP_TO(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);
+
+	/*
+	 * Set the Read Status Register dummy cycles and dummy address bytes.
+	 */
+	if (table[0] & PROFILE1_DWORD1_RDSR_DUMMY)
+		params->rdsr_dummy = 8;
+	else
+		params->rdsr_dummy = 4;
+
+	if (table[0] & PROFILE1_DWORD1_RDSR_ADDR_BYTES)
+		params->rdsr_addr_nbytes = 4;
+	else
+		params->rdsr_addr_nbytes = 0;
+
+out:
+	kfree(table);
+	return ret;
+}
+
 /**
  * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
  * @nor:		pointer to a 'struct spi_nor'
@@ -2197,6 +2291,10 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
 			err = spi_nor_parse_microchip_sfdp(nor, param_header);
 			break;
 
+		case SFDP_PROFILE1_ID:
+			err = spi_nor_parse_profile1(nor, param_header, params);
+			break;
+
 		default:
 			break;
 		}
@@ -2925,6 +3023,8 @@ int spi_nor_scan(struct spi_nor *nor)
 	if (ret)
 		return ret;
 
+	nor->rdsr_dummy = params.rdsr_dummy;
+	nor->rdsr_addr_nbytes = params.rdsr_addr_nbytes;
 	nor->name = mtd->name;
 	nor->size = mtd->size;
 	nor->erase_size = mtd->erasesize;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 4394cb6e16..295583ed29 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -391,6 +391,8 @@ enum spi_nor_pp_command_index {
 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];
@@ -445,6 +447,9 @@ struct spi_flash {
  * @read_opcode:	the read opcode
  * @read_dummy:		the dummy needed by the read operation
  * @program_opcode:	the program opcode
+ * @rdsr_dummy		dummy cycles needed for Read Status Register command.
+ * @rdsr_addr_nbytes:	dummy address bytes needed for Read Status Register
+ *			command.
  * @bank_read_cmd:	Bank read cmd
  * @bank_write_cmd:	Bank write cmd
  * @bank_curr:		Current flash bank
@@ -486,6 +491,8 @@ struct spi_nor {
 	u8			read_opcode;
 	u8			read_dummy;
 	u8			program_opcode;
+	u8			rdsr_dummy;
+	u8			rdsr_addr_nbytes;
 #ifdef CONFIG_SPI_FLASH_BAR
 	u8			bank_read_cmd;
 	u8			bank_write_cmd;
-- 
2.30.0