Change in flashrom[master]: [RFC] spi25_statusreg, flashchips: add SR2 read/write support

[Nikolai Artemiev (Code Review)]

Nikolai Artemiev has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/58476 )

Change subject: [RFC] spi25_statusreg, flashchips: add SR2 read/write support
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[RFC] 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.

Support for each of the specific SR2-related commands is represented
using new feature flags. This may not be an ideal representation, but it
should be fairly easy to swap out for a better one.

BUG=b:195381327,b:153800563
TEST=logged SPI values, ran writeprotect commands that read/wrote SR2
BRANCH=none

Signed-off-by: Nikolai Artemiev

with '#' will be ignored, and an empty message aborts the commit.

Change-Id: Icc2dea15763bde6c5da1e13d30040069f4f6d585
---
M flash.h
M flashchips.c
M spi25_statusreg.c
3 files changed, 39 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/76/58476/1

diff --git a/flash.h b/flash.h
index c3f99c9..ccae05d 100644
--- a/flash.h
+++ b/flash.h
@@ -142,6 +142,12 @@
 #define FEATURE_ERASED_ZERO	(1 << 17)
 #define FEATURE_NO_ERASE	(1 << 18)

+#define FEATURE_WRSR_EXT_SR2    (1 << 19)
+#define FEATURE_WRSR2_31H       (1 << 20)
+#define FEATURE_RDSR2_35H       (1 << 21)
+#define FEATURE_RDCR1_15H       (1 << 22)
+
+
 #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 434c46d..0d0a8e2 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -6317,7 +6317,8 @@
    	.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_SR2 | FEATURE_RDSR2_35H,
    	.tested		= TEST_OK_PREW,
    	.probe		= probe_spi_rdid,
    	.probe_timing	= TIMING_ZERO,
@@ -6754,7 +6755,8 @@
    	.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_31H | FEATURE_RDSR2_35H,
    	.tested		= TEST_OK_PREW,
    	.probe		= probe_spi_rdid,
    	.probe_timing	= TIMING_ZERO,
@@ -6866,7 +6868,8 @@
    	.total_size	= 8192,
    	.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_SR2 | FEATURE_RDSR2_35H,
    	.tested		= TEST_OK_PREW,
    	.probe		= probe_spi_rdid,
    	.probe_timing	= TIMING_ZERO,
diff --git a/spi25_statusreg.c b/spi25_statusreg.c
index 8e8eead..0eb2af4 100644
--- a/spi25_statusreg.c
+++ b/spi25_statusreg.c
@@ -91,6 +91,26 @@
    	write_cmd[1] = value;
    	write_cmd_len = 2;
    }
+	else if (reg == STATUS2) {
+		if (feature_bits & FEATURE_WRSR_EXT_SR2) {
+			/* 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))
+				return 1;
+
+			write_cmd[0] = JEDEC_WRSR;
+			write_cmd[1] = sr1;
+			write_cmd[2] = value;
+			write_cmd_len = 3;
+		}
+		else if (feature_bits & FEATURE_WRSR2_31H) {
+			write_cmd[0] = 0x31;
+			write_cmd[1] = value;
+			write_cmd_len = 2;
+		}
+	}
    if(write_cmd_len == 0) {
    	msg_cerr("Cannot write register: not supported by chip\n");
    	return 1;
@@ -112,11 +132,18 @@

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;

if (reg == STATUS1) {
    	read_cmd = JEDEC_RDSR;
    }
+	else if (reg == STATUS2 && (feature_bits & FEATURE_RDSR2_35H)) {
+		read_cmd = 0x35;
+	}
+	else if (reg == CONFIG1 && (feature_bits & FEATURE_RDCR1_15H)) {
+		read_cmd = 0x15;
+	}
    else {
    	msg_cerr("Cannot read register: not supported by chip\n");
    	return 1;