drivers/elog: Add support for early elog

Add support to log events during the preram stages.

BUG=b:117884485
BRANCH=None
TEST=Add an event log from romstage, boot to ChromeOS

Change-Id: Ia69515961da3bc72740f9b048a53d91af79c5b0d
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/29358
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

3 files changed, 23 insertions, 5 deletions

diff --git a/src/drivers/elog/Kconfig b/src/drivers/elog/Kconfig
index c5ff7aeffe63..da8a5fa220b5 100644
--- a/src/drivers/elog/Kconfig
+++ b/src/drivers/elog/Kconfig
@@ -36,6 +36,12 @@ config ELOG_CBMEM
 	 but it means that events added at runtime via the SMI handler
 	 will not be reflected in the CBMEM copy of the log.
 
+config ELOG_PRERAM
+	bool
+	default n
+	help
+	  This option will enable event logging from the preram stage.
+
 endif
 
 config ELOG_GSMI
diff --git a/src/drivers/elog/Makefile.inc b/src/drivers/elog/Makefile.inc
index 79a7cc0f7f18..cce1c3d6d7b1 100644
--- a/src/drivers/elog/Makefile.inc
+++ b/src/drivers/elog/Makefile.inc
@@ -1,3 +1,7 @@
+bootblock-$(CONFIG_ELOG_PRERAM) += elog.c
+verstage-$(CONFIG_ELOG_PRERAM) += elog.c
+romstage-$(CONFIG_ELOG_PRERAM) += elog.c
+postcar-$(CONFIG_ELOG_PRERAM) += elog.c
 ramstage-$(CONFIG_ELOG) += elog.c
 
 smm-$(CONFIG_ELOG_GSMI) += elog.c gsmi.c
diff --git a/src/drivers/elog/elog.c b/src/drivers/elog/elog.c
index e006ded265c6..0d16b2bed599 100644
--- a/src/drivers/elog/elog.c
+++ b/src/drivers/elog/elog.c
@@ -70,6 +70,14 @@ struct elog_state {
 
 static struct elog_state g_elog_state CAR_GLOBAL;
 
+#define ELOG_SIZE (4 * KiB)
+static uint8_t elog_mirror_buf[ELOG_SIZE] CAR_GLOBAL;
+
+static void *get_elog_mirror_buffer(void)
+{
+	return car_get_var_ptr(elog_mirror_buf);
+}
+
 static inline struct region_device *mirror_dev_get(void)
 {
 	struct elog_state *es = car_get_var_ptr(&g_elog_state);
@@ -706,9 +714,9 @@ static int elog_find_flash(void)
 		return -1;
 	}
 
-	if (region_device_sz(rdev) < 4*KiB) {
-		printk(BIOS_WARNING, "ELOG: Needs a minimum size of 4KiB: %zu\n",
-			region_device_sz(rdev));
+	if (region_device_sz(rdev) < ELOG_SIZE) {
+		printk(BIOS_WARNING, "ELOG: Needs a minimum size of %dKiB: %zu\n",
+			ELOG_SIZE / KiB, region_device_sz(rdev));
 		return -1;
 	}
 
@@ -716,7 +724,7 @@ static int elog_find_flash(void)
 		region_device_offset(rdev), region_device_sz(rdev));
 
 	/* Keep 4KiB max size until large malloc()s have been fixed. */
-	total_size = MIN(4*KiB, region_device_sz(rdev));
+	total_size = MIN(ELOG_SIZE, region_device_sz(rdev));
 	rdev_chain(rdev, rdev, 0, total_size);
 
 	es->full_threshold = total_size - reserved_space;
@@ -828,7 +836,7 @@ int elog_init(void)
 		return -1;
 
 	elog_size = region_device_sz(&es->nv_dev);
-	mirror_buffer = malloc(elog_size);
+	mirror_buffer = get_elog_mirror_buffer();
 	if (!mirror_buffer) {
 		printk(BIOS_ERR, "ELOG: Unable to allocate backing store\n");
 		return -1;