wifi: brcmfmac: of: Fetch Apple properties

On Apple ARM64 platforms, firmware selection requires two properties
that come from system firmware: the module-instance (aka "island", a
codename representing a given hardware platform) and the antenna-sku.
We map Apple's module codenames to board_types in the form
"apple,<module-instance>".

The mapped board_type is added to the DTS file in that form, while the
antenna-sku is forwarded by our bootloader from the Apple Device Tree
into the FDT. Grab them from the DT so firmware selection can use
them.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/E1oZDnn-0077aS-NA@rmk-PC.armlinux.org.uk

drivers/net/wireless/broadcom/brcm80211/brcmfmac/common.h

@@ -53,6 +53,7 @@ struct brcmf_mp_device {
 	struct brcmfmac_pd_cc *country_codes;
 	const char	*board_type;
 	unsigned char	mac[ETH_ALEN];
+	const char	*antenna_sku;
 	union {
 		struct brcmfmac_sdio_pd sdio;
 	} bus;

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

@@ -70,14 +70,24 @@ void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
 {
 	struct brcmfmac_sdio_pd *sdio = &settings->bus.sdio;
 	struct device_node *root, *np = dev->of_node;
+	const char *prop;
 	int irq;
 	int err;
 	u32 irqf;
 	u32 val;
 
+	/* Apple ARM64 platforms have their own idea of board type, passed in
+	 * via the device tree. They also have an antenna SKU parameter
+	 */
+	if (!of_property_read_string(np, "brcm,board-type", &prop))
+		settings->board_type = prop;
+
+	if (!of_property_read_string(np, "apple,antenna-sku", &prop))
+		settings->antenna_sku = prop;
+
 	/* Set board-type to the first string of the machine compatible prop */
 	root = of_find_node_by_path("/");
-	if (root) {
+	if (root && !settings->board_type) {
 		char *board_type;
 		const char *tmp;