[RFC net-next 1/4] net: marvell: prestera: try to load previous fw version

@@ -166,6 +166,8 @@ struct prestera_fw_evtq {
 };
 
 struct prestera_fw {
+	struct prestera_fw_rev rev_supp;
+	const struct firmware *bin;
 	struct workqueue_struct *wq;
 	struct prestera_device dev;
 	u8 __iomem *ldr_regs;

@@ -576,25 +578,24 @@ static void prestera_fw_rev_parse(const struct prestera_fw_header *hdr,
 static int prestera_fw_rev_check(struct prestera_fw *fw)
 {
 	struct prestera_fw_rev *rev = &fw->dev.fw_rev;
-	u16 maj_supp = PRESTERA_SUPP_FW_MAJ_VER;
-	u16 min_supp = PRESTERA_SUPP_FW_MIN_VER;
 
-	if (rev->maj == maj_supp && rev->min >= min_supp)
+	if (rev->maj == fw->rev_supp.maj && rev->min >= fw->rev_supp.min)
 		return 0;
 
 	dev_err(fw->dev.dev, "Driver supports FW version only '%u.%u.x'",
-		PRESTERA_SUPP_FW_MAJ_VER, PRESTERA_SUPP_FW_MIN_VER);
+		fw->rev_supp.maj, fw->rev_supp.min);
 
 	return -EINVAL;
 }
 
-static int prestera_fw_hdr_parse(struct prestera_fw *fw,
-				 const struct firmware *img)
+static int prestera_fw_hdr_parse(struct prestera_fw *fw)
 {
-	struct prestera_fw_header *hdr = (struct prestera_fw_header *)img->data;
 	struct prestera_fw_rev *rev = &fw->dev.fw_rev;
+	struct prestera_fw_header *hdr;
 	u32 magic;
 
+	hdr = (struct prestera_fw_header *)fw->bin->data;
+
 	magic = be32_to_cpu(hdr->magic_number);
 	if (magic != PRESTERA_FW_HDR_MAGIC) {
 		dev_err(fw->dev.dev, "FW img hdr magic is invalid");

@@ -609,11 +610,51 @@ static int prestera_fw_hdr_parse(struct prestera_fw *fw,
 	return prestera_fw_rev_check(fw);
 }
 
+static int prestera_fw_get(struct prestera_fw *fw)
+{
+	int ver_maj = PRESTERA_SUPP_FW_MAJ_VER;
+	int ver_min = PRESTERA_SUPP_FW_MIN_VER;
+	char fw_path[128];
+	int err;
+
+pick_fw_ver:
+	snprintf(fw_path, sizeof(fw_path), PRESTERA_FW_PATH_FMT,
+		 ver_maj, ver_min);
+
+	err = request_firmware_direct(&fw->bin, fw_path, fw->dev.dev);
+	if (err) {
+		if (ver_maj == PRESTERA_SUPP_FW_MAJ_VER) {
+			ver_maj--;
+			goto pick_fw_ver;
+		} else {
+			dev_err(fw->dev.dev, "failed to request firmware file\n");
+			return err;
+		}
+	}
+
+	if (ver_maj < PRESTERA_SUPP_FW_MAJ_VER)
+		dev_warn(fw->dev.dev,
+			 "using older FW version %u.%u than expected %u.%u\n",
+			 ver_maj, ver_min,
+			 PRESTERA_SUPP_FW_MAJ_VER, PRESTERA_SUPP_FW_MIN_VER);
+
+	dev_info(fw->dev.dev, "Loading %s ...", fw_path);
+
+	fw->rev_supp.maj = ver_maj;
+	fw->rev_supp.min = ver_min;
+	fw->rev_supp.sub = 0;
+
+	return 0;
+}
+
+static void prestera_fw_put(struct prestera_fw *fw)
+{
+	release_firmware(fw->bin);
+}
+
 static int prestera_fw_load(struct prestera_fw *fw)
 {
 	size_t hlen = sizeof(struct prestera_fw_header);
-	const struct firmware *f;
-	char fw_path[128];
 	int err;
 
 	err = prestera_ldr_wait_reg32(fw, PRESTERA_LDR_READY_REG,

@@ -632,30 +673,26 @@ static int prestera_fw_load(struct prestera_fw *fw)
 
 	fw->ldr_wr_idx = 0;
 
-	snprintf(fw_path, sizeof(fw_path), PRESTERA_FW_PATH_FMT,
-		 PRESTERA_SUPP_FW_MAJ_VER, PRESTERA_SUPP_FW_MIN_VER);
-
-	err = request_firmware_direct(&f, fw_path, fw->dev.dev);
+	err = prestera_fw_get(fw);
 	if (err) {
 		dev_err(fw->dev.dev, "failed to request firmware file\n");
 		return err;
 	}
 
-	err = prestera_fw_hdr_parse(fw, f);
+	err = prestera_fw_hdr_parse(fw);
 	if (err) {
 		dev_err(fw->dev.dev, "FW image header is invalid\n");
 		goto out_release;
 	}
 
-	prestera_ldr_write(fw, PRESTERA_LDR_IMG_SIZE_REG, f->size - hlen);
+	prestera_ldr_write(fw, PRESTERA_LDR_IMG_SIZE_REG, fw->bin->size - hlen);
 	prestera_ldr_write(fw, PRESTERA_LDR_CTL_REG, PRESTERA_LDR_CTL_DL_START);
 
-	dev_info(fw->dev.dev, "Loading %s ...", fw_path);
-
-	err = prestera_ldr_fw_send(fw, f->data + hlen, f->size - hlen);
+	err = prestera_ldr_fw_send(fw, fw->bin->data + hlen,
+				   fw->bin->size - hlen);
 
 out_release:
-	release_firmware(f);
+	prestera_fw_put(fw);
 	return err;
 }