[coreboot-gerrit] Change in coreboot[master]: spi/flash: Add interface to check software write protection

[Patrick Rudolph (Code Review)]

Patrick Rudolph has uploaded this change for review. ( https://review.coreboot.org/27987

Change subject: spi/flash: Add interface to check software write protection
......................................................................

spi/flash: Add interface to check software write protection

* Add a common function to check if the region is write protected by
** SPI controller's "flash protected regions"
** flash status register protection bits

The state of a possible hardware write protection doesn't matter here.

Change-Id: I1a2b75f5c0f183a74d42180dfc0c12d50b9780bb
Signed-off-by: Patrick Rudolph 
---
M src/drivers/spi/spi_flash.c
M src/include/spi-generic.h
M src/include/spi_flash.h
3 files changed, 50 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/87/27987/1

diff --git a/src/drivers/spi/spi_flash.c b/src/drivers/spi/spi_flash.c
index 87049460..0e8ebd9 100644
--- a/src/drivers/spi/spi_flash.c
+++ b/src/drivers/spi/spi_flash.c
@@ -538,6 +538,36 @@
    }
 }

+int spi_flash_ctrlr_is_region_protected(const struct spi_flash *flash,
+					const struct region *region)
+{
+	const struct spi_ctrlr *ctrlr;
+	const struct spi_flash_ops *ops;
+	struct region flash_region = { 0 };
+
+	if (!flash)
+		return -1;
+
+	flash_region.size = flash->size;
+
+	if (!region_is_subregion(&flash_region, region))
+		return -1;
+
+	ctrlr = flash->spi.ctrlr;
+	ops = flash->ops;
+
+	/* Check controller's "Protected Regions" */
+	if (ctrlr && ctrlr->is_flash_write_protected)
+		return ctrlr->is_flash_write_protected(flash, region);
+
+	/*
+	 * Try to directly check the status register lock-bits in flash.
+	 */
+	if (ops && ops->get_write_protection)
+		return ops->get_write_protection(flash, region) > 0;
+
+	return -1;
+}

int spi_flash_ctrlr_protect_region(const struct spi_flash *flash,
    				const struct region *region)
diff --git a/src/include/spi-generic.h b/src/include/spi-generic.h
index e3e7f82..c95b4ae 100644
--- a/src/include/spi-generic.h
+++ b/src/include/spi-generic.h
@@ -145,6 +145,8 @@
    			struct spi_flash *flash);
    int (*flash_protect)(const struct spi_flash *flash,
    			const struct region *region);
+	int (*is_flash_write_protected)(const struct spi_flash *flash,
+					const struct region *region);
 };

/*-----------------------------------------------------------------------
diff --git a/src/include/spi_flash.h b/src/include/spi_flash.h
index f33b59a..b8bb7bd 100644
--- a/src/include/spi_flash.h
+++ b/src/include/spi_flash.h
@@ -198,6 +198,24 @@
    				const struct region *region);

/*
+ * Check if provided region is write protected.
+ * It first tries to use its controller, if available.
+ * If the controller doesn't support flash protections, try to query the lock
+ * bits in the status register of the flash device (requires flash vendor
+ * specific support).
+ *
+ * @param flash The flash device to operate on
+ * @param region The region to lock
+ * @Return < 0 on error, 0 if region isn't fully protected else 1 on success.
+ *
+ * Possible errors:
+ * * Invalid region specified
+ * * Requested region layout can't be directly applied on flash
+ * * SPI bus error
+ */
+int spi_flash_ctrlr_is_region_protected(const struct spi_flash *flash,
+					const struct region *region);
+/*
  * This function is provided to support spi flash command-response transactions.
  * Only 2 vectors are supported and the 'func' is called with appropriate
  * write and read buffers together. This can be used for chipsets that