wcn36xx: Allow firmware name to be overridden by DT

The WLAN NV firmware blob differs between platforms, and possibly
devices, so add support in the wcn36xx driver for reading the path of
this file from DT in order to allow these files to live in a generic
file system (or linux-firmware).

For some reason the parent (wcnss_ctrl) also needs to upload this blob,
so rather than specifying the same information in both nodes wcn36xx
reads the string from the parent's of_node.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Aníbal Limón <anibal.limon@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210824171225.686683-1-bjorn.andersson@linaro.org

drivers/net/wireless/ath/wcn36xx/main.c

@@ -1503,6 +1503,13 @@ static int wcn36xx_probe(struct platform_device *pdev)
 		goto out_wq;
 	}
 
+	wcn->nv_file = WLAN_NV_FILE;
+	ret = of_property_read_string(wcn->dev->parent->of_node, "firmware-name", &wcn->nv_file);
+	if (ret < 0 && ret != -EINVAL) {
+		wcn36xx_err("failed to read \"firmware-name\" property: %d\n", ret);
+		goto out_wq;
+	}
+
 	wcn->smd_channel = qcom_wcnss_open_channel(wcnss, "WLAN_CTRL", wcn36xx_smd_rsp_process, hw);
 	if (IS_ERR(wcn->smd_channel)) {
 		wcn36xx_err("failed to open WLAN_CTRL channel\n");

drivers/net/wireless/ath/wcn36xx/smd.c

@@ -504,10 +504,10 @@ int wcn36xx_smd_load_nv(struct wcn36xx *wcn)
 	u16 fm_offset = 0;
 
 	if (!wcn->nv) {
-		ret = request_firmware(&wcn->nv, WLAN_NV_FILE, wcn->dev);
+		ret = request_firmware(&wcn->nv, wcn->nv_file, wcn->dev);
 		if (ret) {
 			wcn36xx_err("Failed to load nv file %s: %d\n",
-				      WLAN_NV_FILE, ret);
+				    wcn->nv_file, ret);
 			goto out;
 		}
 	}

drivers/net/wireless/ath/wcn36xx/wcn36xx.h

@@ -199,6 +199,7 @@ struct wcn36xx {
 	struct device		*dev;
 	struct list_head	vif_list;
 
+	const char		*nv_file;
 	const struct firmware	*nv;
 
 	u8			fw_revision;