[M] Change in flashrom[master]: writeprotect,ichspi,spi25: handle register access constraints

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has submitted this change. ( https://review.coreboot.org/c/flashrom/+/69129 )

Change subject: writeprotect,ichspi,spi25: handle register access constraints
......................................................................

writeprotect,ichspi,spi25: handle register access constraints

Make the spi25 register read/write functions return SPI_INVALID_OPCODE
if the programmer blocks the read/write opcode for the register.

Likewise, make ichspi read/write register functions return
SPI_INVALID_OPCODE for registers >SR1 as they cannot be accessd.

Make writeprotect ignore SPI_INVALID_OPCODE unless it is trying to
read/write SR1, which should always be supported.

BUG=b:253715389,b:253713774,b:240229722
BRANCH=none
TEST=flashrom --wp-{enable,disable,range,list,status} on dedede

Change-Id: I2145749dcc51f4556550650dab5aa1049f879c45
Signed-off-by: Nikolai Artemiev 
Reviewed-on: https://review.coreboot.org/c/flashrom/+/69129
Tested-by: build bot (Jenkins) 
Reviewed-by: Edward O'Callaghan 
---
M ichspi.c
M spi25_statusreg.c
M writeprotect.c
3 files changed, 74 insertions(+), 8 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Edward O'Callaghan: Looks good to me, approved

diff --git a/ichspi.c b/ichspi.c
index 4588502..2b6c7ae 100644
--- a/ichspi.c
+++ b/ichspi.c
@@ -1400,8 +1400,12 @@
    const struct hwseq_data *hwseq_data = get_hwseq_data_from_context(flash);

if (reg != STATUS1) {
-		msg_perr("%s: only supports STATUS1\n", __func__);
-		return -1;
+		msg_pdbg("%s: only supports STATUS1\n", __func__);
+		/*
+		 * Return SPI_INVALID_OPCODE to be consistent with spi_read_register()
+		 * and make error handling simpler even though this isn't a SPI master.
+		 */
+		return SPI_INVALID_OPCODE;
    }
    msg_pdbg("Reading Status register\n");

@@ -1421,8 +1425,12 @@
    const struct hwseq_data *hwseq_data = get_hwseq_data_from_context(flash);

if (reg != STATUS1) {
-		msg_perr("%s: only supports STATUS1\n", __func__);
-		return -1;
+		msg_pdbg("%s: only supports STATUS1\n", __func__);
+		/*
+		 * Return SPI_INVALID_OPCODE to be consistent with spi_write_register()
+		 * and make error handling simpler even though this isn't a SPI master.
+		 */
+		return SPI_INVALID_OPCODE;
    }
    msg_pdbg("Writing status register\n");

diff --git a/spi25_statusreg.c b/spi25_statusreg.c
index b178b2e..726ca8c 100644
--- a/spi25_statusreg.c
+++ b/spi25_statusreg.c
@@ -19,6 +19,7 @@

#include "flash.h"
 #include "chipdrivers.h"
+#include "programmer.h"
 #include "spi.h"

/* === Generic functions === */
@@ -129,6 +130,11 @@
    	return 1;
    }

+	if (!flash->mst->spi.probe_opcode(flash, write_cmd[0])) {
+		msg_pdbg("%s: write to register %d not supported by programmer, ignoring.\n", __func__, reg);
+		return SPI_INVALID_OPCODE;
+	}
+
    uint8_t enable_cmd;
    if (feature_bits & FEATURE_WRSR_WREN) {
    	enable_cmd = JEDEC_WREN;
@@ -238,6 +244,11 @@
    	return 1;
    }

+	if (!flash->mst->spi.probe_opcode(flash, read_cmd)) {
+		msg_pdbg("%s: read from register %d not supported by programmer.\n", __func__, reg);
+		return SPI_INVALID_OPCODE;
+	}
+
    /* FIXME: No workarounds for driver/hardware bugs in generic code. */
    /* JEDEC_RDSR_INSIZE=1 but wbsio needs 2 */
    uint8_t readarr[2];
diff --git a/writeprotect.c b/writeprotect.c
index 49586b4..d8ffa68 100644
--- a/writeprotect.c
+++ b/writeprotect.c
@@ -19,6 +19,7 @@
 #include <stdlib.h>
 #include <string.h>

+#include "spi.h"
 #include "flash.h"
 #include "libflashrom.h"
 #include "chipdrivers.h"
@@ -30,18 +31,38 @@
  */
 static int wp_write_register(const struct flashctx *flash, enum flash_reg reg, uint8_t value)
 {
+	int ret;
    if ((flash->mst->buses_supported & BUS_PROG) && flash->mst->opaque.write_register) {
-		return flash->mst->opaque.write_register(flash, reg, value);
+		ret = flash->mst->opaque.write_register(flash, reg, value);
+	} else {
+		ret = spi_write_register(flash, reg, value);
    }
-	return spi_write_register(flash, reg, value);
+
+	/* Writing SR1 should always be supported, ignore errors for other registers. */
+	if (ret == SPI_INVALID_OPCODE && reg != STATUS1) {
+		msg_pdbg("%s: write to register %d not supported by programmer, ignoring.\n", __func__, reg);
+		ret = 0;
+	}
+	return ret;
 }

static int wp_read_register(const struct flashctx *flash, enum flash_reg reg, uint8_t *value)
 {
+	int ret;
    if ((flash->mst->buses_supported & BUS_PROG) && flash->mst->opaque.read_register) {
-		return flash->mst->opaque.read_register(flash, reg, value);
+		ret = flash->mst->opaque.read_register(flash, reg, value);
+	} else {
+		ret = spi_read_register(flash, reg, value);
    }
-	return spi_read_register(flash, reg, value);
+
+	/* Reading SR1 should always be supported, ignore errors for other registers. */
+	if (ret == SPI_INVALID_OPCODE && reg != STATUS1) {
+		msg_pdbg("%s: read from register %d not is supported by programmer, "
+			  "writeprotect operations will assume it contains 0x00.\n", __func__, reg);
+		*value = 0;
+		ret = 0;
+	}
+	return ret;
 }

/** Read and extract a single bit from the chip's registers */