wifi: rtw88: usb: Support USB 3 with RTL8822CU/RTL8822BU

The Realtek wifi 5 devices which support USB 3 are weird: when first
plugged in, they pretend to be USB 2. The driver needs to send some
commands to the device, which make it disappear and come back as a
USB 3 device.

Implement the required commands in rtw88.

When a USB 3 device is plugged into a USB 2 port, rtw88 will try to
switch it to USB 3 mode only once. The device will disappear and come
back still in USB 2 mode, of course.

Some people experience heavy interference in the 2.4 GHz band in
USB 3 mode, so add a module parameter switch_usb_mode with the
default value 1 to let people disable the switching.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/77906c62-5674-426f-bde1-1b2a12a0339d@gmail.com

1 files changed, 84 insertions, 0 deletions

diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index a55ca5a24227..251a5726f3ee 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -14,6 +14,11 @@
 #include "ps.h"
 #include "usb.h"
 
+static bool rtw_switch_usb_mode = true;
+module_param_named(switch_usb_mode, rtw_switch_usb_mode, bool, 0644);
+MODULE_PARM_DESC(switch_usb_mode,
+		 "Set to N to disable switching to USB 3 mode to avoid potential interference in the 2.4 GHz band (default: Y)");
+
 #define RTW_USB_MAX_RXQ_LEN	512
 
 struct rtw_usb_txcb {
@@ -841,6 +846,77 @@ static void rtw_usb_intf_deinit(struct rtw_dev *rtwdev,
 	usb_set_intfdata(intf, NULL);
 }
 
+static int rtw_usb_switch_mode_new(struct rtw_dev *rtwdev)
+{
+	enum usb_device_speed cur_speed;
+	u8 id = rtwdev->chip->id;
+	bool can_switch;
+	u32 pad_ctrl2;
+
+	if (rtw_read8(rtwdev, REG_SYS_CFG2 + 3) == 0x20)
+		cur_speed = USB_SPEED_SUPER;
+	else
+		cur_speed = USB_SPEED_HIGH;
+
+	if (cur_speed == USB_SPEED_SUPER)
+		return 0;
+
+	pad_ctrl2 = rtw_read32(rtwdev, REG_PAD_CTRL2);
+
+	can_switch = !!(pad_ctrl2 & (BIT_MASK_USB23_SW_MODE_V1 |
+				     BIT_USB3_USB2_TRANSITION));
+
+	if (!can_switch) {
+		rtw_dbg(rtwdev, RTW_DBG_USB,
+			"Switching to USB 3 mode unsupported by the chip\n");
+		return 0;
+	}
+
+	/* At this point cur_speed is USB_SPEED_HIGH. If we already tried
+	 * to switch don't try again - it's a USB 2 port.
+	 */
+	if (u32_get_bits(pad_ctrl2, BIT_MASK_USB23_SW_MODE_V1) == BIT_USB_MODE_U3)
+		return 0;
+
+	/* Enable IO wrapper timeout */
+	if (id == RTW_CHIP_TYPE_8822B || id == RTW_CHIP_TYPE_8821C)
+		rtw_write8_clr(rtwdev, REG_SW_MDIO + 3, BIT(0));
+
+	u32p_replace_bits(&pad_ctrl2, BIT_USB_MODE_U3, BIT_MASK_USB23_SW_MODE_V1);
+	pad_ctrl2 |= BIT_RSM_EN_V1;
+
+	rtw_write32(rtwdev, REG_PAD_CTRL2, pad_ctrl2);
+	rtw_write8(rtwdev, REG_PAD_CTRL2 + 1, 4);
+
+	rtw_write16_set(rtwdev, REG_SYS_PW_CTRL, BIT_APFM_OFFMAC);
+	usleep_range(1000, 1001);
+	rtw_write32_set(rtwdev, REG_PAD_CTRL2, BIT_NO_PDN_CHIPOFF_V1);
+
+	return 1;
+}
+
+static int rtw_usb_switch_mode(struct rtw_dev *rtwdev)
+{
+	u8 id = rtwdev->chip->id;
+
+	if (id != RTW_CHIP_TYPE_8822C && id != RTW_CHIP_TYPE_8822B)
+		return 0;
+
+	if (!rtwdev->efuse.usb_mode_switch) {
+		rtw_dbg(rtwdev, RTW_DBG_USB,
+			"Switching to USB 3 mode disabled by chip's efuse\n");
+		return 0;
+	}
+
+	if (!rtw_switch_usb_mode) {
+		rtw_dbg(rtwdev, RTW_DBG_USB,
+			"Switching to USB 3 mode disabled by module parameter\n");
+		return 0;
+	}
+
+	return rtw_usb_switch_mode_new(rtwdev);
+}
+
 int rtw_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 {
 	struct rtw_dev *rtwdev;
@@ -896,6 +972,14 @@ int rtw_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 		goto err_destroy_rxwq;
 	}
 
+	ret = rtw_usb_switch_mode(rtwdev);
+	if (ret) {
+		/* Not a fail, but we do need to skip rtw_register_hw. */
+		rtw_dbg(rtwdev, RTW_DBG_USB, "switching to USB 3 mode\n");
+		ret = 0;
+		goto err_destroy_rxwq;
+	}
+
 	ret = rtw_register_hw(rtwdev, rtwdev->hw);
 	if (ret) {
 		rtw_err(rtwdev, "failed to register hw\n");