spi25_statusreg.c: add SR3 read/write support

Adds support for reading and writing the third status register.

Feature flag is not needed because it would never on its own control
whether SR3 access occurs.  If added, it would be in one of three
possible states: wrong, useless or redundant.

Change-Id: Id987c544c02da2b956e6ad2c525265cac8f15be1
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/60230
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-by: Nikolai Artemiev <nartemiev@google.com>
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/70980
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/flash.h b/flash.h
index c6173ba..eff4d58 100644
--- a/flash.h
+++ b/flash.h
@@ -177,6 +177,7 @@
 	INVALID_REG = 0,
 	STATUS1,
 	STATUS2,
+	STATUS3,
 	MAX_REGISTERS
 };
 
diff --git a/spi.h b/spi.h
index 7c393c5..2992312 100644
--- a/spi.h
+++ b/spi.h
@@ -131,6 +131,11 @@
 #define JEDEC_RDSR2_OUTSIZE	0x01
 #define JEDEC_RDSR2_INSIZE	0x01
 
+/* Read Status Register 3 */
+#define JEDEC_RDSR3		0x15
+#define JEDEC_RDSR3_OUTSIZE	0x01
+#define JEDEC_RDSR3_INSIZE	0x01
+
 /* Status Register Bits */
 #define SPI_SR_WIP	(0x01 << 0)
 #define SPI_SR_WEL	(0x01 << 1)
@@ -152,6 +157,11 @@
 #define JEDEC_WRSR2_OUTSIZE	0x02
 #define JEDEC_WRSR2_INSIZE	0x00
 
+/* Write Status Register 3 */
+#define JEDEC_WRSR3		0x11
+#define JEDEC_WRSR3_OUTSIZE	0x02
+#define JEDEC_WRSR3_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 6b16839..0f43056 100644
--- a/spi25_statusreg.c
+++ b/spi25_statusreg.c
@@ -66,6 +66,11 @@
 		}
 		msg_cerr("Cannot write SR2: unsupported by chip\n");
 		return 1;
+	case STATUS3:
+		write_cmd[0] = JEDEC_WRSR3;
+		write_cmd[1] = value;
+		write_cmd_len = JEDEC_WRSR3_OUTSIZE;
+		break;
 	default:
 		msg_cerr("Cannot write register: unknown register\n");
 		return 1;
@@ -153,6 +158,9 @@
 		}
 		msg_cerr("Cannot read SR2: unsupported by chip\n");
 		return 1;
+	case STATUS3:
+		read_cmd = JEDEC_RDSR3;
+		break;
 	default:
 		msg_cerr("Cannot read register: unknown register\n");
 		return 1;