mtd: spi-nor-core: Parse xSPI Profile 1.0 table

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>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index d9af5cbf97..b3b04db8bf 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];
 };
@@ -2096,6 +2110,86 @@ spi_nor_parse_microchip_sfdp(struct spi_nor *nor,
 }
 
 /**
+ * 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'
  * @params:		pointer to the 'struct spi_nor_flash_parameter' to be
@@ -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;
 		}
@@ -2926,6 +3024,8 @@ 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;