brcmfmac: firmware: Allow per-board firmware binaries

After some crashes in the 3D engine (!) on the Samsung GT-I8530
it turns out that the main firmware file can be device dependent,
something that was previously only handled for the NVRAM
parameter file.

Rewrite the code a bit so we can a per-board suffixed firmware
binary as well, if this does not exist we fall back to the
canonical firmware name.

Example: a 4330 device with the OF board compatible is
"samsung,gavini". We will first try
"brcmfmac4330-sdio.samsung,gavini.bin" then "brcmfmac4330-sdio.bin"
if that does not work.

Cc: phone-devel@vger.kernel.org
Cc: newbyte@disroot.org
Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210711231659.255479-1-linus.walleij@linaro.org

drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c

@@ -594,28 +594,47 @@ static int brcmf_fw_complete_request(const struct firmware *fw,
 	return (cur->flags & BRCMF_FW_REQF_OPTIONAL) ? 0 : ret;
 }
 
+static char *brcm_alt_fw_path(const char *path, const char *board_type)
+{
+	char alt_path[BRCMF_FW_NAME_LEN];
+	char suffix[5];
+
+	strscpy(alt_path, path, BRCMF_FW_NAME_LEN);
+	/* At least one character + suffix */
+	if (strlen(alt_path) < 5)
+		return NULL;
+
+	/* strip .txt or .bin at the end */
+	strscpy(suffix, alt_path + strlen(alt_path) - 4, 5);
+	alt_path[strlen(alt_path) - 4] = 0;
+	strlcat(alt_path, ".", BRCMF_FW_NAME_LEN);
+	strlcat(alt_path, board_type, BRCMF_FW_NAME_LEN);
+	strlcat(alt_path, suffix, BRCMF_FW_NAME_LEN);
+
+	return kstrdup(alt_path, GFP_KERNEL);
+}
+
 static int brcmf_fw_request_firmware(const struct firmware **fw,
 				     struct brcmf_fw *fwctx)
 {
 	struct brcmf_fw_item *cur = &fwctx->req->items[fwctx->curpos];
 	int ret;
 
-	/* nvram files are board-specific, first try a board-specific path */
+	/* Files can be board-specific, first try a board-specific path */
 	if (cur->type == BRCMF_FW_TYPE_NVRAM && fwctx->req->board_type) {
-		char alt_path[BRCMF_FW_NAME_LEN];
+		char *alt_path;
 
-		strlcpy(alt_path, cur->path, BRCMF_FW_NAME_LEN);
-		/* strip .txt at the end */
-		alt_path[strlen(alt_path) - 4] = 0;
-		strlcat(alt_path, ".", BRCMF_FW_NAME_LEN);
-		strlcat(alt_path, fwctx->req->board_type, BRCMF_FW_NAME_LEN);
-		strlcat(alt_path, ".txt", BRCMF_FW_NAME_LEN);
+		alt_path = brcm_alt_fw_path(cur->path, fwctx->req->board_type);
+		if (!alt_path)
+			goto fallback;
 
 		ret = request_firmware(fw, alt_path, fwctx->dev);
+		kfree(alt_path);
 		if (ret == 0)
 			return ret;
 	}
 
+fallback:
 	return request_firmware(fw, cur->path, fwctx->dev);
 }
 
@@ -660,6 +679,7 @@ int brcmf_fw_get_firmwares(struct device *dev, struct brcmf_fw_request *req,
 {
 	struct brcmf_fw_item *first = &req->items[0];
 	struct brcmf_fw *fwctx;
+	char *alt_path;
 	int ret;
 
 	brcmf_dbg(TRACE, "enter: dev=%s\n", dev_name(dev));
@@ -677,9 +697,20 @@ int brcmf_fw_get_firmwares(struct device *dev, struct brcmf_fw_request *req,
 	fwctx->req = req;
 	fwctx->done = fw_cb;
 
-	ret = request_firmware_nowait(THIS_MODULE, true, first->path,
-				      fwctx->dev, GFP_KERNEL, fwctx,
-				      brcmf_fw_request_done);
+	/* First try alternative board-specific path if any */
+	alt_path = brcm_alt_fw_path(first->path, fwctx->req->board_type);
+	if (alt_path) {
+		ret = request_firmware_nowait(THIS_MODULE, true, alt_path,
+					      fwctx->dev, GFP_KERNEL, fwctx,
+					      brcmf_fw_request_done);
+		kfree(alt_path);
+	}
+	/* Else try canonical path */
+	if (ret) {
+		ret = request_firmware_nowait(THIS_MODULE, true, first->path,
+					      fwctx->dev, GFP_KERNEL, fwctx,
+					      brcmf_fw_request_done);
+	}
 	if (ret < 0)
 		brcmf_fw_request_done(NULL, fwctx);