spi25_statusreg: support reading/writing configuration register

One more variation of registers.

This one is read via a separate RDCR command, but written as if it's
SR2 using WRSR_EXT2.

Change-Id: I45f9afcc31f1928ef6263a749596380082963de4
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/66211
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Nikolai Artemiev <nartemiev@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

3 files changed, 33 insertions, 0 deletions

diff --git a/include/flash.h b/include/flash.h
index 197c11ea1..23222c722 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -161,6 +161,9 @@ enum write_granularity {
  */
 #define FEATURE_SCUR		(1 << 24)
 
+/* Whether chip has configuration register (RDCR/WRSR_EXT2 commands) */
+#define FEATURE_CFGR	    (1 << 25)
+
 #define ERASED_VALUE(flash)	(((flash)->chip->feature_bits & FEATURE_ERASED_ZERO) ? 0x00 : 0xff)
 #define UNERASED_VALUE(flash)	(((flash)->chip->feature_bits & FEATURE_ERASED_ZERO) ? 0xff : 0x00)
 
@@ -196,6 +199,7 @@ enum flash_reg {
 	STATUS2,
 	STATUS3,
 	SECURITY,
+	CONFIG,
 	MAX_REGISTERS
 };
 
diff --git a/include/spi.h b/include/spi.h
index c77866c41..505aecd01 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -177,6 +177,11 @@
 #define JEDEC_WRSCUR_OUTSIZE	0x01
 #define JEDEC_WRSCUR_INSIZE	0x00
 
+/* Read Configuration Register */
+#define JEDEC_RDCR		0x15
+#define JEDEC_RDCR_OUTSIZE	0x01
+#define JEDEC_RDCR_INSIZE	0x01
+
 /* Enter 4-byte Address Mode */
 #define JEDEC_ENTER_4_BYTE_ADDR_MODE	0xB7
 
diff --git a/spi25_statusreg.c b/spi25_statusreg.c
index 2859b2320..b178b2e37 100644
--- a/spi25_statusreg.c
+++ b/spi25_statusreg.c
@@ -107,6 +107,23 @@ int spi_write_register(const struct flashctx *flash, enum flash_reg reg, uint8_t
 		 */
 		msg_cerr("Cannot write SECURITY: unsupported by design\n");
 		return 1;
+	case CONFIG:
+		/*
+		 * This one is read via a separate command, but written as if it's SR2
+		 * in FEATURE_WRSR_EXT2 case of WRSR command.
+		 */
+		if (feature_bits & FEATURE_CFGR) {
+			write_cmd[0] = JEDEC_WRSR;
+			if (spi_read_register(flash, STATUS1, &write_cmd[1])) {
+				msg_cerr("Writing CONFIG failed: failed to read SR1 for writeback.\n");
+				return 1;
+			}
+			write_cmd[2] = value;
+			write_cmd_len = 3;
+			break;
+		}
+		msg_cerr("Cannot write CONFIG: unsupported by chip\n");
+		return 1;
 	default:
 		msg_cerr("Cannot write register: unknown register\n");
 		return 1;
@@ -209,6 +226,13 @@ int spi_read_register(const struct flashctx *flash, enum flash_reg reg, uint8_t
 		}
 		msg_cerr("Cannot read SECURITY: unsupported by chip\n");
 		return 1;
+	case CONFIG:
+		if (feature_bits & FEATURE_CFGR) {
+			read_cmd = JEDEC_RDCR;
+			break;
+		}
+		msg_cerr("Cannot read CONFIG: unsupported by chip\n");
+		return 1;
 	default:
 		msg_cerr("Cannot read register: unknown register\n");
 		return 1;