drivers/spi/spi_flash: add flash region protection to controller

Provide a spi controller specific protection callback to take
advantage of special spi flash controllers that have internal
protection registers built into the implementation. It's an
optional callback for spi controllers.

BUG=b:69614064

Change-Id: Ie50a6ce3bbda32620a25dd26fda1af944940bf28
Signed-off-by: Aaron Durbn <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/22879
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/drivers/spi/spi_flash.c

@@ -459,3 +459,29 @@ void lb_spi_flash(struct lb_header *header)
 		flash->erase_cmd = CMD_BLOCK_ERASE;
 	}
 }
+
+
+int spi_flash_ctrlr_protect_region(const struct spi_flash *flash,
+					const struct region *region)
+{
+	const struct spi_ctrlr *ctrlr;
+	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;
+
+	if (!ctrlr)
+		return -1;
+
+	if (ctrlr->flash_protect)
+		return ctrlr->flash_protect(flash, region);
+
+	return -1;
+}

src/include/spi-generic.h

@@ -16,6 +16,7 @@
 #ifndef _SPI_GENERIC_H_
 #define _SPI_GENERIC_H_
 
+#include <commonlib/region.h>
 #include <stdint.h>
 #include <stddef.h>
 
@@ -115,6 +116,7 @@ struct spi_flash;
  *
  * flash_probe:	Specialized probe function provided by SPI flash
  *			controllers.
+ * flash_protect: Protect a region of flash using the SPI flash controller.
  */
 struct spi_ctrlr {
 	int (*claim_bus)(const struct spi_slave *slave);
@@ -128,6 +130,8 @@ struct spi_ctrlr {
 	bool deduct_cmd_len;
 	int (*flash_probe)(const struct spi_slave *slave,
 				struct spi_flash *flash);
+	int (*flash_protect)(const struct spi_flash *flash,
+				const struct region *region);
 };
 
 /*-----------------------------------------------------------------------

src/include/spi_flash.h

@@ -120,4 +120,9 @@ int chipset_volatile_group_end(const struct spi_flash *flash);
  * if CONFIG_BOOT_DEVICE_SPI_FLASH is enabled. */
 const struct spi_flash *boot_device_spi_flash(void);
 
+/* Protect a region of spi flash using its controller, if available. Returns
+ * < 0 on error, else 0 on success. */
+int spi_flash_ctrlr_protect_region(const struct spi_flash *flash,
+					const struct region *region);
+
 #endif /* _SPI_FLASH_H_ */