sar: Fix semantics of `get_wifi_sar_cbfs_filename()`

Currently, if `get_wifi_sar_cbfs_filename()` returns NULL, then
`get_wifi_sar_limits()` assumes that the default filename is used for
CBFS SAR file. This prevents a board from supporting different models
using the same firmware -- some which require SAR support and some
which don't.

This change updates the logic in `get_wifi_sar_limits()` to return
early if filename is not provided by the mainboard. In order to
maintain the same logic as before, current mainboards are updated to
return WIFI_SAR_CBFS_DEFAULT_FILENAME instead of NULL in default
case.

Change-Id: I68b5bdd213767a3cd81fe41ace66540acd68e26a
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51485
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

7 files changed, 17 insertions, 32 deletions

diff --git a/src/mainboard/google/octopus/variants/bloog/variant.c b/src/mainboard/google/octopus/variants/bloog/variant.c
index 5682ac3eb0..28f2ce8f54 100644
--- a/src/mainboard/google/octopus/variants/bloog/variant.c
+++ b/src/mainboard/google/octopus/variants/bloog/variant.c
@@ -28,7 +28,6 @@ enum {
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
 	uint32_t sku_id = google_chromeec_get_board_sku();
 
 	switch (sku_id) {
@@ -36,18 +35,16 @@ const char *get_wifi_sar_cbfs_filename(void)
 	case SKU_34_BLOOG:
 	case SKU_35_BLOOG:
 	case SKU_36_BLOOG:
-		filename = "wifi_sar-bloog.hex";
-		break;
+		return "wifi_sar-bloog.hex";
 	case SKU_49_BLOOGUARD:
 	case SKU_50_BLOOGUARD:
 	case SKU_51_BLOOGUARD:
 	case SKU_52_BLOOGUARD:
 	case SKU_53_BIPSHIP:
 	case SKU_54_BIPSHIP:
-		filename = "wifi_sar-blooguard.hex";
-		break;
+		return "wifi_sar-blooguard.hex";
 	}
-	return filename;
+	return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 }
 
 const char *mainboard_vbt_filename(void)
diff --git a/src/mainboard/google/octopus/variants/bobba/variant.c b/src/mainboard/google/octopus/variants/bobba/variant.c
index 2d09270148..5765eb7768 100644
--- a/src/mainboard/google/octopus/variants/bobba/variant.c
+++ b/src/mainboard/google/octopus/variants/bobba/variant.c
@@ -18,13 +18,12 @@ enum {
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
 	uint32_t sku_id = google_chromeec_get_board_sku();
 
 	if (sku_id >= 33 && sku_id <= 44)
-		filename = "wifi_sar-droid.hex";
+		return "wifi_sar-droid.hex";
 
-	return filename;
+	return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 }
 
 void variant_smi_sleep(u8 slp_typ)
diff --git a/src/mainboard/google/octopus/variants/casta/variant.c b/src/mainboard/google/octopus/variants/casta/variant.c
index a5b948cf62..b9165a7aab 100644
--- a/src/mainboard/google/octopus/variants/casta/variant.c
+++ b/src/mainboard/google/octopus/variants/casta/variant.c
@@ -8,13 +8,12 @@
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
 	uint32_t sku_id = google_chromeec_get_board_sku();
 
 	if (sku_id == 2)
-		filename = "wifi_sar-bluebird.hex";
+		return "wifi_sar-bluebird.hex";
 
-	return filename;
+	return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 }
 
 bool variant_ext_usb_status(unsigned int port_type, unsigned int port_id)
diff --git a/src/mainboard/google/octopus/variants/fleex/variant.c b/src/mainboard/google/octopus/variants/fleex/variant.c
index 6333b074dd..63908e2f68 100644
--- a/src/mainboard/google/octopus/variants/fleex/variant.c
+++ b/src/mainboard/google/octopus/variants/fleex/variant.c
@@ -32,12 +32,10 @@ void variant_smi_sleep(u8 slp_typ)
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
-
 	if (!is_lte_sku())
-		filename = "wifi_sar-fleex.hex";
+		return "wifi_sar-fleex.hex";
 
-	return filename;
+	return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 }
 
 void variant_update_devtree(struct device *dev)
diff --git a/src/mainboard/google/octopus/variants/foob/variant.c b/src/mainboard/google/octopus/variants/foob/variant.c
index 8cc4a3df0b..aeddc3b3b2 100644
--- a/src/mainboard/google/octopus/variants/foob/variant.c
+++ b/src/mainboard/google/octopus/variants/foob/variant.c
@@ -25,11 +25,10 @@ void variant_update_devtree(struct device *dev)
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
 	uint32_t sku_id = SKU_UNKNOWN;
 
 	sku_id = google_chromeec_get_board_sku();
 	if (sku_id == 9)
-		filename = "wifi_sar-foob360.hex";
-	return filename;
+		return "wifi_sar-foob360.hex";
+	return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 }
diff --git a/src/mainboard/google/octopus/variants/meep/variant.c b/src/mainboard/google/octopus/variants/meep/variant.c
index df4dbd69ea..4e5c4bebf4 100644
--- a/src/mainboard/google/octopus/variants/meep/variant.c
+++ b/src/mainboard/google/octopus/variants/meep/variant.c
@@ -8,7 +8,6 @@
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
 	uint32_t sku_id = google_chromeec_get_board_sku();
 
 	switch (sku_id) {
@@ -16,16 +15,14 @@ const char *get_wifi_sar_cbfs_filename(void)
 	case SKU_2_MEEP:
 	case SKU_3_MEEP:
 	case SKU_4_MEEP:
-		filename = "wifi_sar-meep.hex";
-		break;
+		return "wifi_sar-meep.hex";
 	case SKU_49_VORTININJA:
 	case SKU_50_VORTININJA:
 	case SKU_51_VORTININJA:
 	case SKU_52_VORTININJA:
-		filename = "wifi_sar-vortininja.hex";
-		break;
+		return "wifi_sar-vortininja.hex";
 	}
-	return filename;
+	return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 }
 
 const char *mainboard_vbt_filename(void)
diff --git a/src/mainboard/google/octopus/variants/phaser/mainboard.c b/src/mainboard/google/octopus/variants/phaser/mainboard.c
index 4997ce452f..b5b53539b7 100644
--- a/src/mainboard/google/octopus/variants/phaser/mainboard.c
+++ b/src/mainboard/google/octopus/variants/phaser/mainboard.c
@@ -6,14 +6,10 @@
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
-	const char *filename = NULL;
 	uint32_t sku_id;
 
-	if (google_chromeec_cbi_get_sku_id(&sku_id))
-		return NULL;
+	if (google_chromeec_cbi_get_sku_id(&sku_id) || (sku_id != 5))
+		return WIFI_SAR_CBFS_DEFAULT_FILENAME;
 
-	if (sku_id == 5)
-		filename = "wifi_sar-laser.hex";
-
-	return filename;
+	return "wifi_sar-laser.hex";
 }