Bluetooth: btbcm: Support per-board firmware variants

There are provedly different firmware variants for the different
phones using some of these chips. These were extracted from a few
Samsung phones:

37446 BCM4334B0.samsung,codina-tmo.hcd
37366 BCM4334B0.samsung,golden.hcd
37403 BCM4334B0.samsung,kyle.hcd
37366 BCM4334B0.samsung,skomer.hcd

This patch supports the above naming schedule with inserting
[.board_name] between the firmware name and ".hcd". This scheme
is the same as used by the companion BRCM wireless chips
as can be seen in
drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
or just by looking at the firmwares in linux-firmware/brcm.

Currently we only support board variants using the device
tree compatible string as board type, but other schemes are
possible.

This makes it possible to successfully load a few unique
firmware variants for some Samsung phones.

Cc: phone-devel@vger.kernel.org
Cc: Markuss Broks <markuss.broks@gmail.com>
Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btbcm.c

@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/firmware.h>
 #include <linux/dmi.h>
+#include <linux/of.h>
 #include <asm/unaligned.h>
 
 #include <net/bluetooth/bluetooth.h>
@@ -29,7 +30,7 @@
 #define BDADDR_BCM43341B (&(bdaddr_t) {{0xac, 0x1f, 0x00, 0x1b, 0x34, 0x43}})
 
 #define BCM_FW_NAME_LEN			64
-#define BCM_FW_NAME_COUNT_MAX		2
+#define BCM_FW_NAME_COUNT_MAX		4
 /* For kmalloc-ing the fw-name array instead of putting it on the stack */
 typedef char bcm_fw_name[BCM_FW_NAME_LEN];
 
@@ -476,6 +477,42 @@ static const struct bcm_subver_table bcm_usb_subver_table[] = {
 	{ }
 };
 
+/*
+ * This currently only looks up the device tree board appendix,
+ * but can be expanded to other mechanisms.
+ */
+static const char *btbcm_get_board_name(struct device *dev)
+{
+#ifdef CONFIG_OF
+	struct device_node *root;
+	char *board_type;
+	const char *tmp;
+	int len;
+	int i;
+
+	root = of_find_node_by_path("/");
+	if (!root)
+		return NULL;
+
+	if (of_property_read_string_index(root, "compatible", 0, &tmp))
+		return NULL;
+
+	/* get rid of any '/' in the compatible string */
+	len = strlen(tmp) + 1;
+	board_type = devm_kzalloc(dev, len, GFP_KERNEL);
+	strscpy(board_type, tmp, len);
+	for (i = 0; i < board_type[i]; i++) {
+		if (board_type[i] == '/')
+			board_type[i] = '-';
+	}
+	of_node_put(root);
+
+	return board_type;
+#else
+	return NULL;
+#endif
+}
+
 int btbcm_initialize(struct hci_dev *hdev, bool *fw_load_done)
 {
 	u16 subver, rev, pid, vid;
@@ -483,12 +520,15 @@ int btbcm_initialize(struct hci_dev *hdev, bool *fw_load_done)
 	struct hci_rp_read_local_version *ver;
 	const struct bcm_subver_table *bcm_subver_table;
 	const char *hw_name = NULL;
+	const char *board_name;
 	char postfix[16] = "";
 	int fw_name_count = 0;
 	bcm_fw_name *fw_name;
 	const struct firmware *fw;
 	int i, err;
 
+	board_name = btbcm_get_board_name(&hdev->dev);
+
 	/* Reset */
 	err = btbcm_reset(hdev);
 	if (err)
@@ -549,11 +589,21 @@ int btbcm_initialize(struct hci_dev *hdev, bool *fw_load_done)
 		return -ENOMEM;
 
 	if (hw_name) {
+		if (board_name) {
+			snprintf(fw_name[fw_name_count], BCM_FW_NAME_LEN,
+				 "brcm/%s%s.%s.hcd", hw_name, postfix, board_name);
+			fw_name_count++;
+		}
 		snprintf(fw_name[fw_name_count], BCM_FW_NAME_LEN,
 			 "brcm/%s%s.hcd", hw_name, postfix);
 		fw_name_count++;
 	}
 
+	if (board_name) {
+		snprintf(fw_name[fw_name_count], BCM_FW_NAME_LEN,
+			 "brcm/BCM%s.%s.hcd", postfix, board_name);
+		fw_name_count++;
+	}
 	snprintf(fw_name[fw_name_count], BCM_FW_NAME_LEN,
 		 "brcm/BCM%s.hcd", postfix);
 	fw_name_count++;