3 files changed, 209 insertions, 0 deletions
diff --git a/src/drivers/spi/Kconfig b/src/drivers/spi/Kconfig
index 86e609c7ae..72fcec5e93 100644
--- a/src/drivers/spi/Kconfig
+++ b/src/drivers/spi/Kconfig
@@ -189,6 +189,11 @@ config SPI_FLASH_FORCE_4_BYTE_ADDR_MODE
 	  On some platforms with SPI flashes larger than 16MB, the SPI flash may need
 	  to remain in 4-byte addressing mode.
 
+config SPI_FLASH_SFDP
+	bool
+	help
+	  Include serial flash discoverable parameters (SFDP) support.
+
 endif # SPI_FLASH
 
 config HAVE_EM100PRO_SPI_CONSOLE_SUPPORT
diff --git a/src/drivers/spi/Makefile.mk b/src/drivers/spi/Makefile.mk
index 97c3d63d49..d873c90627 100644
--- a/src/drivers/spi/Makefile.mk
+++ b/src/drivers/spi/Makefile.mk
@@ -31,6 +31,7 @@ $(1)-$(CONFIG_SPI_FLASH_SST) += sst.c
 $(1)-$(CONFIG_SPI_FLASH_STMICRO) += stmicro.c
 $(1)-$(CONFIG_SPI_FLASH_WINBOND) += winbond.c
 $(1)-$(CONFIG_SPI_FLASH_ISSI) += issi.c
+$(1)-$(CONFIG_SPI_FLASH_SFDP) += spi_flash_sfdp.c
 endef
 
 $(eval $(call add_spi_stage,bootblock,_EARLY))
diff --git a/src/drivers/spi/spi_flash_sfdp.c b/src/drivers/spi/spi_flash_sfdp.c
new file mode 100644
index 0000000000..807a33be58
--- /dev/null
+++ b/src/drivers/spi/spi_flash_sfdp.c
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <console/console.h>
+#include <spi-generic.h>
+#include <spi_flash.h>
+#include <types.h>
+
+#include "spi_flash_internal.h"
+
+/*
+ * Assumptions (not) made in the code:
+ * - code is supposed to be endian-safe
+ * - requested SFDP data blocks are small enough to fit into the SPI controller buffer, so no
+ *   spi_crop_chunk calls are needed
+ *
+ * Limitations:
+ * - only legacy access protocol supported:
+ *   - only NOR flash
+ *   - read SFDP instruction is sufficient and no fetch SFDP instruction needed
+ *   - always 3 byte addresses for SFDP
+ *   - only 1 bit SPI mode supported
+ *   - always 8 dummy cycles after the address is sent
+*/
+
+#define CMD_READ_SFDP			0x5a
+
+static enum cb_err read_sfdp_data(const struct spi_flash *flash, uint32_t offset, size_t len,
+				  uint8_t *buf)
+{
+	uint8_t buf_cmd[5];
+
+	buf_cmd[0] = CMD_READ_SFDP;
+	buf_cmd[1] = offset >> 16 & 0xff;
+	buf_cmd[2] = offset >> 8 & 0xff;
+	buf_cmd[3] = offset >> 0 & 0xff;
+	buf_cmd[4] = 0; /* dummy byte */
+
+	/* TODO: use spi_crop_chunk to break up larger transfers */
+	if (spi_flash_cmd_multi(&flash->spi, buf_cmd, sizeof(buf_cmd), buf, len))
+		return CB_ERR;
+
+	return CB_SUCCESS;
+}
+
+#define SFDP_HEADER_OFFSET			0
+#define SFDP_HEADER_LEN				(2 * sizeof(uint32_t))
+#define SFDP_HEADER_SIGNATURE			0x50444653 /* LE: "SFDP" */
+#define SFDP_HEADER_ACCESS_PROTOCOL_LEGACY	0xff
+/* header byte offsets */
+#define SFDP_HEADER_SIGNATURE_0			0
+#define SFDP_HEADER_SIGNATURE_1			1
+#define SFDP_HEADER_SIGNATURE_2			2
+#define SFDP_HEADER_SIGNATURE_3			3
+#define SFDP_HEADER_MINOR_REV			4
+#define SFDP_HEADER_MAJOR_REV			5
+#define SFDP_HEADER_PARAMETER_HEADER_NUMBER	6
+#define SFDP_HEADER_ACCESS_PROTOCOL		7
+
+static enum cb_err get_sfdp_header(const struct spi_flash *flash, uint16_t *sfdp_revision,
+				   uint8_t *number_of_parameter_headers,
+				   uint8_t *access_prototcol)
+{
+	uint8_t buf[SFDP_HEADER_LEN];
+	uint32_t signature;
+
+	if (read_sfdp_data(flash, SFDP_HEADER_OFFSET, SFDP_HEADER_LEN, buf) != CB_SUCCESS)
+		return CB_ERR;
+
+	signature = buf[SFDP_HEADER_SIGNATURE_0] | buf[SFDP_HEADER_SIGNATURE_1] << 8 |
+		buf[SFDP_HEADER_SIGNATURE_2] << 16 | buf[SFDP_HEADER_SIGNATURE_3] << 24;
+	*sfdp_revision = buf[SFDP_HEADER_MINOR_REV] | buf[SFDP_HEADER_MAJOR_REV] << 8;
+	*number_of_parameter_headers = buf[SFDP_HEADER_PARAMETER_HEADER_NUMBER] + 1;
+	*access_prototcol = buf[SFDP_HEADER_ACCESS_PROTOCOL];
+
+	if (signature != SFDP_HEADER_SIGNATURE)
+		return CB_ERR;
+
+	/* We make the assumption in the code that the legacy access protocol is used */
+	if (*access_prototcol != SFDP_HEADER_ACCESS_PROTOCOL_LEGACY)
+		return CB_ERR;
+
+	return CB_SUCCESS;
+}
+
+#define SFDP_PARAMETER_HEADER_LEN		(2 * sizeof(uint32_t))
+#define SFDP_PARAMETER_HEADER_OFFSET(n)		(SFDP_HEADER_OFFSET + SFDP_HEADER_LEN + \
+						 n * SFDP_PARAMETER_HEADER_LEN)
+/* parameter header byte offsets */
+#define SFDP_PARAMETER_HEADER_ID_LSB		0
+#define SFDP_PARAMETER_HEADER_MINOR_REV		1
+#define SFDP_PARAMETER_HEADER_MAJOR_REV		2
+#define SFDP_PARAMETER_HEADER_LENGTH_DWORDS	3
+#define SFDP_PARAMETER_HEADER_POINTER_0		4
+#define SFDP_PARAMETER_HEADER_POINTER_1		5
+#define SFDP_PARAMETER_HEADER_POINTER_2		6
+#define SFDP_PARAMETER_HEADER_ID_MSB		7
+
+/* get_sfdp_parameter_header_by_index must be called with a valid index */
+static enum cb_err get_sfdp_parameter_header_by_index(const struct spi_flash *flash,
+						      uint8_t index, uint16_t *id,
+						      uint16_t *revision,
+						      uint8_t *length_dwords,
+						      uint32_t *table_pointer)
+{
+	uint8_t buf[SFDP_PARAMETER_HEADER_LEN];
+
+	if (read_sfdp_data(flash, SFDP_PARAMETER_HEADER_OFFSET(index),
+		       SFDP_PARAMETER_HEADER_LEN, buf) != CB_SUCCESS)
+		return CB_ERR;
+
+	*id = buf[SFDP_PARAMETER_HEADER_ID_LSB] | buf[SFDP_PARAMETER_HEADER_ID_MSB] << 8;
+	*revision = buf[SFDP_PARAMETER_HEADER_MINOR_REV] |
+		buf[SFDP_PARAMETER_HEADER_MAJOR_REV] << 8;
+	*length_dwords = buf[SFDP_PARAMETER_HEADER_LENGTH_DWORDS];
+	*table_pointer = buf[SFDP_PARAMETER_HEADER_POINTER_0] |
+		buf[SFDP_PARAMETER_HEADER_POINTER_1] << 8 |
+		buf[SFDP_PARAMETER_HEADER_POINTER_2] << 16;
+
+	/* the parameter table pointer byte address must be DWORD-aligned */
+	if (!IS_ALIGNED(*table_pointer, sizeof(uint32_t)))
+		return CB_ERR;
+
+	/* TODO: check id validity? */
+
+	return CB_SUCCESS;
+}
+
+void spi_flash_print_sfdp_headers(const struct spi_flash *flash)
+{
+	enum cb_err stat;
+	uint16_t sfdp_rev;
+	uint8_t param_header_count;
+	uint8_t access_protocol;
+
+	if (get_sfdp_header(flash, &sfdp_rev, &param_header_count, &access_protocol) !=
+			CB_SUCCESS) {
+		printk(BIOS_ERR, "Failed to read SFDP header from SPI flash\n");
+		return;
+	}
+
+	printk(BIOS_DEBUG, "SFDP header found in SPI flash.\n");
+	printk(BIOS_DEBUG, "major rev %#x, minor rev %#x, access protocol %#x, "
+	       "number of headers %d\n", sfdp_rev >> 8, sfdp_rev & 0xff, access_protocol,
+	       param_header_count);
+
+	uint16_t tbl_id;
+	uint16_t tbl_rev;
+	uint8_t tbl_len_dwords;
+	uint32_t tbl_pointer;
+
+	for (unsigned int i = 0; i < param_header_count; i++) {
+		stat = get_sfdp_parameter_header_by_index(flash, i, &tbl_id, &tbl_rev,
+							  &tbl_len_dwords, &tbl_pointer);
+
+		if (stat == CB_SUCCESS) {
+			printk(BIOS_DEBUG, "SFPD header with index %d:\n", i);
+			printk(BIOS_DEBUG, "  table ID %#x, major rev %#x, minor rev %#x\n",
+			       tbl_id, tbl_rev >> 8, tbl_rev & 0xff);
+			printk(BIOS_DEBUG, "  table pointer %#x, table length DWORDS %#x\n",
+			       tbl_pointer, tbl_len_dwords);
+		} else {
+			printk(BIOS_ERR, "Cound't read SFPD header with index %d.\n", i);
+		}
+	}
+}
+
+static inline enum cb_err find_sfdp_parameter_header(const struct spi_flash *flash,
+						     uint16_t table_id, uint16_t *revision,
+						     uint8_t *length_dwords,
+						     uint32_t *table_pointer)
+{
+	enum cb_err stat;
+	uint16_t sfdp_rev;
+	uint8_t param_header_count;
+	uint8_t access_protocol;
+
+	if (get_sfdp_header(flash, &sfdp_rev, &param_header_count, &access_protocol) !=
+			CB_SUCCESS)
+		return CB_ERR;
+
+	/* TODO: add version check? */
+
+	uint16_t tbl_id;
+	uint16_t tbl_rev;
+	uint8_t tbl_len_dwords;
+	uint32_t tbl_pointer;
+
+	for (unsigned int i = 0; i < param_header_count; i++) {
+		stat = get_sfdp_parameter_header_by_index(flash, i, &tbl_id, &tbl_rev,
+							  &tbl_len_dwords, &tbl_pointer);
+
+		if (stat == CB_SUCCESS && tbl_id == table_id) {
+			*revision = tbl_rev;
+			*length_dwords = tbl_len_dwords;
+			*table_pointer = tbl_pointer;
+			return CB_SUCCESS;
+		}
+	}
+
+	printk(BIOS_WARNING, "Cound't find SFPD header with table ID %#x.\n", table_id);
+
+	return CB_ERR;
+}