spi25_statusreg,flashchips: add SR2 read/write support

This patch adds support for reading and writing the second status
register and enables it on a limited set of flash chips.

Chip support for RDSR2/WRSR2/extended WRSR is represented using feature
flags to be consistent with how other SPI capabilities are represented.

BUG=b:195381327,b:153800563
BRANCH=none
TEST=flashrom -{r,w,E}
TEST=flashrom --wp-{enable,disable,range,list,status} at end of patch series
TEST=logged SR2 read/write values during wp commands

Change-Id: I34a503b0958e8f2f22a2a993a6ea529eb46b41db
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/58570
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

4 files changed, 53 insertions, 3 deletions

diff --git a/flash.h b/flash.h
index f1a8b340..cd40fa3f 100644
--- a/flash.h
+++ b/flash.h
@@ -140,6 +140,9 @@ enum write_granularity {
 #define FEATURE_ERASED_ZERO	(1 << 17)
 #define FEATURE_NO_ERASE	(1 << 18)
 
+#define FEATURE_WRSR_EXT	(1 << 19)
+#define FEATURE_WRSR2		(1 << 20)
+
 #define ERASED_VALUE(flash)	(((flash)->chip->feature_bits & FEATURE_ERASED_ZERO) ? 0x00 : 0xff)
 
 enum test_state {
diff --git a/flashchips.c b/flashchips.c
index 21eeb395..9e10b5d2 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -6317,7 +6317,7 @@ const struct flashchip flashchips[] = {
 		.total_size	= 16384,
 		.page_size	= 256,
 		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42, erase 0x44 */
-		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP | FEATURE_WRSR_EXT,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -6706,7 +6706,8 @@ const struct flashchip flashchips[] = {
 		.model_id	= GIGADEVICE_GD25Q256D,
 		.total_size	= 32768,
 		.page_size	= 256,
-		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP | FEATURE_4BA_WREN,
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP | FEATURE_4BA_WREN |
+				  FEATURE_WRSR_EXT | FEATURE_WRSR2,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
@@ -6754,7 +6755,7 @@ const struct flashchip flashchips[] = {
 		.total_size	= 4096,
 		.page_size	= 256,
 		/* OTP: 1024B total, 256B reserved; read 0x48; write 0x42, erase 0x44 */
-		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
+		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP | FEATURE_WRSR2,
 		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
diff --git a/spi.h b/spi.h
index 09da5795..845b6c2a 100644
--- a/spi.h
+++ b/spi.h
@@ -131,6 +131,11 @@
 #define JEDEC_RDSR_OUTSIZE	0x01
 #define JEDEC_RDSR_INSIZE	0x01
 
+/* Read Status Register 2 */
+#define JEDEC_RDSR2		0x35
+#define JEDEC_RDSR2_OUTSIZE	0x01
+#define JEDEC_RDSR2_INSIZE	0x01
+
 /* Status Register Bits */
 #define SPI_SR_WIP	(0x01 << 0)
 #define SPI_SR_WEL	(0x01 << 1)
@@ -146,6 +151,12 @@
 #define JEDEC_WRSR		0x01
 #define JEDEC_WRSR_OUTSIZE	0x02
 #define JEDEC_WRSR_INSIZE	0x00
+#define JEDEC_WRSR_EXT_OUTSIZE	0x03
+
+/* Write Status Register 2 */
+#define JEDEC_WRSR2		0x31
+#define JEDEC_WRSR2_OUTSIZE	0x02
+#define JEDEC_WRSR2_INSIZE	0x00
 
 /* Enter 4-byte Address Mode */
 #define JEDEC_ENTER_4_BYTE_ADDR_MODE	0xB7
diff --git a/spi25_statusreg.c b/spi25_statusreg.c
index 0d7bc25b..31d6c769 100644
--- a/spi25_statusreg.c
+++ b/spi25_statusreg.c
@@ -101,6 +101,33 @@ int spi_write_register(const struct flashctx *flash, enum flash_reg reg, uint8_t
 		write_cmd[1] = value;
 		write_cmd_len = JEDEC_WRSR_OUTSIZE;
 		break;
+	case STATUS2:
+		if (feature_bits & FEATURE_WRSR2) {
+			write_cmd[0] = JEDEC_WRSR2;
+			write_cmd[1] = value;
+			write_cmd_len = JEDEC_WRSR2_OUTSIZE;
+			break;
+		}
+		if (feature_bits & FEATURE_WRSR_EXT) {
+			/*
+			 * Writing SR2 with an extended WRSR command requires
+			 * writing SR1 along with SR2, so just read SR1 and
+			 * write it back
+			 */
+			uint8_t sr1;
+
+			if (spi_read_register(flash, STATUS1, &sr1)) {
+				msg_cerr("Writing SR2 failed: failed to read SR1 for writeback.\n");
+				return 1;
+			}
+			write_cmd[0] = JEDEC_WRSR;
+			write_cmd[1] = sr1;
+			write_cmd[2] = value;
+			write_cmd_len = JEDEC_WRSR_EXT_OUTSIZE;
+			break;
+		}
+		msg_cerr("Cannot write SR2: unsupported by chip\n");
+		return 1;
 	default:
 		msg_cerr("Cannot write register: unknown register\n");
 		return 1;
@@ -122,12 +149,20 @@ int spi_write_register(const struct flashctx *flash, enum flash_reg reg, uint8_t
 
 int spi_read_register(const struct flashctx *flash, enum flash_reg reg, uint8_t *value)
 {
+	int feature_bits = flash->chip->feature_bits;
 	uint8_t read_cmd;
 
 	switch (reg) {
 	case STATUS1:
 		read_cmd = JEDEC_RDSR;
 		break;
+	case STATUS2:
+		if (feature_bits & (FEATURE_WRSR_EXT | FEATURE_WRSR2)) {
+			read_cmd = JEDEC_RDSR2;
+			break;
+		}
+		msg_cerr("Cannot read SR2: unsupported by chip\n");
+		return 1;
 	default:
 		msg_cerr("Cannot read register: unknown register\n");
 		return 1;