Bluetooth: mt7921s: Enable SCO over I2S

The driver has to issue the specific command to enable Bluetooth SCO over
the I2S/PCM interface on mt7921s, that is supported since the firmware
with version 20211222191101 was added, and the patch would not cause any
harm even when the old firmware is applied.

The SCO profile with the patch was tested by setting up a VOIP application,
connected to HFP device, checked telephony function can work normally.
Co-developed-by: NSean Wang <sean.wang@mediatek.com>
Signed-off-by: NSean Wang <sean.wang@mediatek.com>
Signed-off-by: NMark Chen <mark-yw.chen@mediatek.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btmtk.h

@@ -7,8 +7,12 @@
 
 #define HCI_WMT_MAX_EVENT_SIZE		64
 
+#define BTMTK_WMT_REG_WRITE 0x1
 #define BTMTK_WMT_REG_READ 0x2
 
+#define MT7921_PINMUX_0 0x70005050
+#define MT7921_PINMUX_1 0x70005054
+
 enum {
 	BTMTK_WMT_PATCH_DWNLD = 0x1,
 	BTMTK_WMT_TEST = 0x2,
@@ -76,6 +80,22 @@ struct btmtk_wakeon {
 	__le16 wakeup_delay;
 } __packed;
 
+struct btmtk_sco {
+	u8 clock_config;
+	u8 transmit_format_config;
+	u8 channel_format_config;
+	u8 channel_select_config;
+} __packed;
+
+struct reg_write_cmd {
+	u8 type;
+	u8 rsv;
+	u8 num;
+	__le32 addr;
+	__le32 data;
+	__le32 mask;
+} __packed;
+
 struct btmtk_hci_wmt_params {
 	u8 op;
 	u8 flag;

drivers/bluetooth/btmtksdio.c

@@ -830,6 +830,66 @@ static int btmtksdio_mtk_reg_read(struct hci_dev *hdev, u32 reg, u32 *val)
 	return err;
 }
 
+static int btmtksdio_mtk_reg_write(struct hci_dev *hdev, u32 reg, u32 val, u32 mask)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	const struct reg_write_cmd reg_write = {
+		.type = 1,
+		.num = 1,
+		.addr = cpu_to_le32(reg),
+		.data = cpu_to_le32(val),
+		.mask = cpu_to_le32(mask),
+	};
+	int err, status;
+
+	wmt_params.op = BTMTK_WMT_REGISTER;
+	wmt_params.flag = BTMTK_WMT_REG_WRITE;
+	wmt_params.dlen = sizeof(reg_write);
+	wmt_params.data = &reg_write;
+	wmt_params.status = &status;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0)
+		bt_dev_err(hdev, "Failed to write reg (%d)", err);
+
+	return err;
+}
+
+static int btmtksdio_sco_setting(struct hci_dev *hdev)
+{
+	const struct btmtk_sco sco_setting = {
+		.clock_config = 0x49,
+		.channel_format_config = 0x80,
+	};
+	struct sk_buff *skb;
+	u32 val;
+	int err;
+
+	/* Enable SCO over I2S/PCM for MediaTek chipset */
+	skb =  __hci_cmd_sync(hdev, 0xfc72, sizeof(sco_setting),
+			      &sco_setting, HCI_CMD_TIMEOUT);
+	if (IS_ERR(skb))
+		return PTR_ERR(skb);
+
+	kfree_skb(skb);
+
+	err = btmtksdio_mtk_reg_read(hdev, MT7921_PINMUX_0, &val);
+	if (err < 0)
+		return err;
+
+	val |= 0x11000000;
+	err = btmtksdio_mtk_reg_write(hdev, MT7921_PINMUX_0, val, ~0);
+	if (err < 0)
+		return err;
+
+	err = btmtksdio_mtk_reg_read(hdev, MT7921_PINMUX_1, &val);
+	if (err < 0)
+		return err;
+
+	val |= 0x00000101;
+	return btmtksdio_mtk_reg_write(hdev, MT7921_PINMUX_1, val, ~0);
+}
+
 static int btmtksdio_setup(struct hci_dev *hdev)
 {
 	struct btmtksdio_dev *bdev = hci_get_drvdata(hdev);
@@ -862,6 +922,14 @@ static int btmtksdio_setup(struct hci_dev *hdev)
 		err = mt79xx_setup(hdev, fwname);
 		if (err < 0)
 			return err;
+
+		/* Enable SCO over I2S/PCM */
+		err = btmtksdio_sco_setting(hdev);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to enable SCO setting (%d)", err);
+			return err;
+		}
+
 		break;
 	case 0x7663:
 	case 0x7668: