[M] Change in flashrom[master]: flashrom.c: Supplement `chip->unlock()` calls with wp unlocking

[Edward O'Callaghan (Code Review)]

Attention is currently required from: Nikolai Artemiev.

Hello Nikolai Artemiev,

I'd like you to do a code review.
Please visit

https://review.coreboot.org/c/flashrom/+/69517

to review the following change.

Change subject: flashrom.c: Supplement `chip->unlock()` calls with wp unlocking
......................................................................

flashrom.c: Supplement `chip->unlock()` calls with wp unlocking

The full writeprotect implementation has proper support and
ability to unlock flash over spi25_statusreg.c. Therefore if
the required bits are available for the given chip prefer
proper writeprotect support instead of adhoc spi25_statusreg.c
helpers.

BUG=b:237485865
BRANCH=none
TEST=make

Change-Id: I74b3f5d3a17749ea60485b916b2d87467a5d8b2f
CoAuthored-by: Nikolai Artemiev 
Signed-off-by: Nikolai Artemiev 
Signed-off-by: Edward O'Callaghan 
---
M flashrom.c
M include/flash.h
2 files changed, 65 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/17/69517/1

diff --git a/flashrom.c b/flashrom.c
index b1782d9..d422d98 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1684,6 +1684,32 @@
    return 0;
 }

+static int unlock_flash_wp(struct flashctx *const flash)
+{
+	struct flashrom_wp_cfg *unlocked_cfg = NULL;
+
+	/* Save old WP config */
+	if (flashrom_wp_cfg_new(&flash->old_wp_cfg) != FLASHROM_WP_OK)
+		return -1;
+	if (flashrom_wp_read_cfg(flash->old_wp_cfg, flash) != FLASHROM_WP_OK)
+		return -1;
+
+	/* Disable WP */
+	if (flashrom_wp_cfg_new(&unlocked_cfg) != FLASHROM_WP_OK)
+		return -1;
+	flashrom_wp_set_range(unlocked_cfg, 0, 0);
+	flashrom_wp_set_mode(unlocked_cfg, FLASHROM_WP_MODE_DISABLED);
+
+	enum flashrom_wp_result ret = flashrom_wp_write_cfg(flash, unlocked_cfg);
+
+	flashrom_wp_cfg_release(unlocked_cfg);
+
+	if(ret != FLASHROM_WP_OK)
+		return -1;
+
+	return 0;
+}
+
 int prepare_flash_access(struct flashctx *const flash,
    		 const bool read_it, const bool write_it,
    		 const bool erase_it, const bool verify_it)
@@ -1706,10 +1732,16 @@
    /* Initialize chip_restore_fn_count before chip unlock calls. */
    flash->chip_restore_fn_count = 0;

-	/* Given the existence of read locks, we want to unlock for read,
-	   erase and write. */
-	if (flash->chip->unlock)
+	/* Clear so we don't try to write back bad cfg in finalize_flash_access() */
+	flash->old_wp_cfg = NULL;
+
+	/* Given the existence of read locks, we want to unlock for read, erase and write. */
+	if (flash->chip->decode_range != NO_DECODE_RANGE_FUNC) {
+		if (unlock_flash_wp(flash) < 0)
+			goto err_out;
+	} else if (flash->chip->unlock) {
    	flash->chip->unlock(flash);
+	}

flash->address_high_byte = -1;
    flash->in_4ba_mode = false;
@@ -1739,11 +1771,17 @@
    return 0;

err_out:
+	flashrom_wp_cfg_release(flash->old_wp_cfg);
    return ret;
 }

void finalize_flash_access(struct flashctx *const flash)
 {
+	if (flash->old_wp_cfg) {
+		flashrom_wp_write_cfg(flash, flash->old_wp_cfg);
+		flashrom_wp_cfg_release(flash->old_wp_cfg);
+		flash->old_wp_cfg = NULL;
+	}
    deregister_chip_restore(flash);
    unmap_flash(flash);
 }
diff --git a/include/flash.h b/include/flash.h
index ea8e25b..4b448f1 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -460,6 +460,8 @@
    	chip_restore_fn_cb_t func;
    	uint8_t status;
    } chip_restore_fn[MAX_CHIP_RESTORE_FUNCTIONS];
+	struct flashrom_wp_cfg *old_wp_cfg;
+
    /* Progress reporting */
    flashrom_progress_callback *progress_callback;
    struct flashrom_progress *progress_state;