soc/intel/common: provide option to invalide MRC cache on recovery

Allow a board/platform to invalidate the normal MRC cache when
hardware retraining is requested in recovery mode. A small 4 byte
payload is used to update the latest data written. It will of course
fail on MRC cache retreival on next usage.

BUG=chrome-os-partner:60592
BRANCH=reef

Change-Id: Ic88cd66802664813562d003f50d54e4a4ea375ef
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/17870
Tested-by: build bot (Jenkins)
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

2 files changed, 38 insertions, 0 deletions

diff --git a/src/soc/intel/common/Kconfig b/src/soc/intel/common/Kconfig
index 1cc856eb5e..68bb38af7a 100644
--- a/src/soc/intel/common/Kconfig
+++ b/src/soc/intel/common/Kconfig
@@ -31,6 +31,10 @@ config HAS_RECOVERY_MRC_CACHE
 	bool
 	default n
 
+config MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN
+	bool
+	default n
+
 config MRC_SETTINGS_VARIABLE_DATA
 	bool
 	default n
diff --git a/src/soc/intel/common/mrc_cache.c b/src/soc/intel/common/mrc_cache.c
index 69e5b00de1..e0d4b7de01 100644
--- a/src/soc/intel/common/mrc_cache.c
+++ b/src/soc/intel/common/mrc_cache.c
@@ -486,6 +486,37 @@ static void protect_mrc_region(void)
 	protect_mrc_cache(DEFAULT_MRC_CACHE);
 }
 
+static void invalidate_normal_cache(void)
+{
+	struct region_file cache_file;
+	struct region_device rdev;
+	const char *name = DEFAULT_MRC_CACHE;
+	const uint32_t invalid = ~MRC_DATA_SIGNATURE;
+
+	/* Invalidate only on recovery mode with retraining enabled. */
+	if (!vboot_recovery_mode_enabled())
+		return;
+	if (!vboot_recovery_mode_memory_retrain())
+		return;
+
+	if (fmap_locate_area_as_rdev_rw(name, &rdev) < 0) {
+		printk(BIOS_ERR, "MRC: Couldn't find '%s' region. Invalidation failed\n",
+			name);
+		return;
+	}
+
+	if (region_file_init(&cache_file, &rdev) < 0) {
+		printk(BIOS_ERR, "MRC: region file invalid for '%s'. Invalidation failed\n",
+			name);
+		return;
+	}
+
+	/* Push an update that consists of 4 bytes that is smaller than the
+	 * MRC metadata as well as an invalid signature. */
+	if (region_file_update_data(&cache_file, &invalid, sizeof(invalid)) < 0)
+		printk(BIOS_ERR, "MRC: invalidation failed for '%s'.\n", name);
+}
+
 static void update_mrc_cache(void *unused)
 {
 	update_mrc_cache_by_type(MRC_TRAINING_DATA);
@@ -493,6 +524,9 @@ static void update_mrc_cache(void *unused)
 	if (IS_ENABLED(CONFIG_MRC_SETTINGS_VARIABLE_DATA))
 		update_mrc_cache_by_type(MRC_VARIABLE_DATA);
 
+	if (IS_ENABLED(CONFIG_MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN))
+		invalidate_normal_cache();
+
 	protect_mrc_region();
 }