[PATCH rtw-next v4] wifi: rtw89: usb: Support switching to USB 3 mode

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

The Realtek wifi 6/7 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 rtw89.

Add a new function rtw89_usb_write32_quiet() to avoid the warnings
when writing to R_{AX,BE}_PAD_CTRL2. Even though the write succeeds,
usb_control_msg() returns -EPROTO, probably because the USB device
disappears immediately. This results in some confusing warnings in
the kernel log.

When a USB 3 device is plugged into a USB 2 port, rtw89 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.

Tested with RTL8832AU, RTL8832BU, RTL8832CU, and RTL8912AU.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
v4:
 - Use a wrapper around rtw89_usb_vendorreq().
 - Add a warning message about 2.4 GHz interference.

v3:
 - Avoid crash when trying to switch.
 - Remove the unwanted module parameter.
 - Support RTL8922AU as well.
 - Use more bit names.
 - Hide the warnings when writing R_AX_PAD_CTRL2.
---
 drivers/net/wireless/realtek/rtw89/reg.h |  27 ++++++
 drivers/net/wireless/realtek/rtw89/usb.c | 104 ++++++++++++++++++++++-
 2 files changed, 128 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/reg.h b/drivers/net/wireless/realtek/rtw89/reg.h
index c9bfb163c32e..76e107091d3b 100644
--- a/drivers/net/wireless/realtek/rtw89/reg.h
+++ b/drivers/net/wireless/realtek/rtw89/reg.h
@@ -164,6 +164,19 @@
 #define R_AX_DBG_PORT_SEL 0x00C0
 #define B_AX_DEBUG_ST_MASK GENMASK(31, 0)
 
+#define R_AX_PAD_CTRL2 0x00C4
+#define B_AX_FORCE_U3_CK BIT(23)
+#define B_AX_USB2_FORCE BIT(22)
+#define B_AX_USB3_FORCE BIT(21)
+#define B_AX_USB3_USB2_TRANSITION BIT(20)
+#define B_AX_USB23_SW_MODE_V1 GENMASK(19, 18)
+#define USB_MODE_U2 0x1
+#define USB_MODE_U3 0x2
+#define B_AX_NO_PDN_CHIPOFF_V1 BIT(17)
+#define B_AX_RSM_EN_V1 BIT(16)
+#define B_AX_MATCH_CNT GENMASK(15, 8)
+#define USB_SWITCH_DELAY 0xF
+
 #define R_AX_PMC_DBG_CTRL2 0x00CC
 #define B_AX_SYSON_DIS_PMCR_AX_WRMSK BIT(2)
 
@@ -4235,6 +4248,20 @@
 #define B_BE_TOGGLE BIT(31)
 #define B_BE_DATA_LINE_MASK GENMASK(30, 0)
 
+#define R_BE_PAD_CTRL2 0x00C4
+#define B_BE_USB23_SW_MODE BIT(31)
+#define B_BE_USB3_GEN_MODE BIT(30)
+#define B_BE_USB3_LANE_MODE BIT(29)
+#define B_BE_USB_AUTO_INSTALL_MASK BIT(28)
+#define B_BE_FORCE_CLK_U2 BIT(25)
+#define B_BE_FORCE_U2_CK BIT(24)
+#define B_BE_FORCE_U3_CK BIT(23)
+#define B_BE_USB2_FORCE BIT(22)
+#define B_BE_USB3_FORCE BIT(21)
+#define B_BE_NO_PDN_CHIPOFF_V1 BIT(17)
+#define B_BE_RSM_EN_V1 BIT(16)
+#define B_BE_MATCH_CNT GENMASK(15, 8)
+
 #define R_BE_PMC_DBG_CTRL2 0x00CC
 #define B_BE_EFUSE_BURN_GNT_MASK GENMASK(31, 24)
 #define B_BE_DIS_IOWRAP_TIMEOUT BIT(16)
diff --git a/drivers/net/wireless/realtek/rtw89/usb.c b/drivers/net/wireless/realtek/rtw89/usb.c
index c6d55e669776..198378018062 100644
--- a/drivers/net/wireless/realtek/rtw89/usb.c
+++ b/drivers/net/wireless/realtek/rtw89/usb.c
@@ -11,8 +11,8 @@
 
 static void rtw89_usb_read_port_complete(struct urb *urb);
 
-static void rtw89_usb_vendorreq(struct rtw89_dev *rtwdev, u32 addr,
-				void *data, u16 len, u8 reqtype)
+static void __rtw89_usb_vendorreq(struct rtw89_dev *rtwdev, u32 addr,
+				  void *data, u16 len, u8 reqtype, bool warn)
 {
 	struct rtw89_usb *rtwusb = rtw89_usb_priv(rtwdev);
 	struct usb_device *udev = rtwusb->udev;
@@ -52,7 +52,7 @@ static void rtw89_usb_vendorreq(struct rtw89_dev *rtwdev, u32 addr,
 
 		if (ret == -ESHUTDOWN || ret == -ENODEV)
 			set_bit(RTW89_FLAG_UNPLUGGED, rtwdev->flags);
-		else if (ret < 0)
+		else if (ret < 0 && warn)
 			rtw89_warn(rtwdev,
 				   "usb %s%u 0x%x fail ret=%d value=0x%x attempt=%d\n",
 				   str_read_write(reqtype == RTW89_USB_VENQT_READ),
@@ -69,6 +69,12 @@ static void rtw89_usb_vendorreq(struct rtw89_dev *rtwdev, u32 addr,
 	}
 }
 
+static void rtw89_usb_vendorreq(struct rtw89_dev *rtwdev, u32 addr,
+				void *data, u16 len, u8 reqtype)
+{
+	__rtw89_usb_vendorreq(rtwdev, addr, data, len, reqtype, true);
+}
+
 static u32 rtw89_usb_read_cmac(struct rtw89_dev *rtwdev, u32 addr)
 {
 	u32 addr32, val32, shift;
@@ -157,6 +163,14 @@ static void rtw89_usb_ops_write32(struct rtw89_dev *rtwdev, u32 addr, u32 val)
 	rtw89_usb_vendorreq(rtwdev, addr, &data, 4, RTW89_USB_VENQT_WRITE);
 }
 
+static void rtw89_usb_write32_quiet(struct rtw89_dev *rtwdev, u32 addr, u32 val)
+{
+	__le32 data = cpu_to_le32(val);
+
+	__rtw89_usb_vendorreq(rtwdev, addr, &data, 4,
+			      RTW89_USB_VENQT_WRITE, false);
+}
+
 static u32
 rtw89_usb_ops_check_and_reclaim_tx_resource(struct rtw89_dev *rtwdev,
 					    u8 txch)
@@ -1059,6 +1073,83 @@ static void rtw89_usb_intf_deinit(struct rtw89_dev *rtwdev,
 	usb_set_intfdata(intf, NULL);
 }
 
+static int rtw89_usb_switch_mode_ax(struct rtw89_dev *rtwdev)
+{
+	u32 pad_ctrl2;
+
+	/* No known USB 3 devices with this chip. */
+	if (rtwdev->chip->chip_id == RTL8851B)
+		return 0;
+
+	pad_ctrl2 = rtw89_usb_ops_read32(rtwdev, R_AX_PAD_CTRL2);
+
+	rtw89_debug(rtwdev, RTW89_DBG_HCI, "%s: pad_ctrl2: %#x\n",
+		    __func__, pad_ctrl2);
+
+	/* Already tried to switch but it's a USB 2 port. */
+	if (u32_get_bits(pad_ctrl2, B_AX_MATCH_CNT) == USB_SWITCH_DELAY)
+		return 0;
+
+	/* Add delay to prevent some platforms would not detect USB switch */
+	u32p_replace_bits(&pad_ctrl2, USB_SWITCH_DELAY, B_AX_MATCH_CNT);
+
+	pad_ctrl2 &= ~(B_AX_FORCE_U3_CK | B_AX_USB2_FORCE |
+		       B_AX_USB3_FORCE | B_AX_USB3_USB2_TRANSITION);
+
+	u32p_replace_bits(&pad_ctrl2, USB_MODE_U3, B_AX_USB23_SW_MODE_V1);
+
+	pad_ctrl2 |= B_AX_NO_PDN_CHIPOFF_V1 | B_AX_RSM_EN_V1;
+
+	rtw89_usb_write32_quiet(rtwdev, R_AX_PAD_CTRL2, pad_ctrl2);
+
+	return 1;
+}
+
+static int rtw89_usb_switch_mode_be(struct rtw89_dev *rtwdev)
+{
+	u32 pad_ctrl2;
+
+	pad_ctrl2 = rtw89_usb_ops_read32(rtwdev, R_BE_PAD_CTRL2);
+
+	rtw89_debug(rtwdev, RTW89_DBG_HCI, "%s: pad_ctrl2: %#x\n",
+		    __func__, pad_ctrl2);
+
+	/* Already tried to switch but it's a USB 2 port. */
+	if (u32_get_bits(pad_ctrl2, B_BE_MATCH_CNT) == USB_SWITCH_DELAY)
+		return 0;
+
+	/* Add delay to prevent some platforms would not detect USB switch */
+	u32p_replace_bits(&pad_ctrl2, USB_SWITCH_DELAY, B_BE_MATCH_CNT);
+
+	pad_ctrl2 |= B_BE_RSM_EN_V1 | B_BE_NO_PDN_CHIPOFF_V1 |
+		     B_BE_USB_AUTO_INSTALL_MASK | B_BE_USB23_SW_MODE;
+
+	pad_ctrl2 &= ~(B_BE_USB3_FORCE | B_BE_USB2_FORCE |
+		       B_BE_FORCE_U3_CK | B_BE_FORCE_U2_CK |
+		       B_BE_FORCE_CLK_U2 | B_BE_USB3_GEN_MODE |
+		       B_BE_USB3_LANE_MODE);
+
+	rtw89_usb_write32_quiet(rtwdev, R_BE_PAD_CTRL2, pad_ctrl2);
+
+	return 1;
+}
+
+static int rtw89_usb_switch_mode(struct rtw89_dev *rtwdev)
+{
+	struct rtw89_usb *rtwusb = rtw89_usb_priv(rtwdev);
+
+	if (rtwusb->udev->speed == USB_SPEED_SUPER) {
+		rtw89_info(rtwdev,
+			   "2.4 GHz performance may be better in a USB 2 port\n");
+		return 0;
+	}
+
+	if (rtwdev->chip->chip_gen == RTW89_CHIP_AX)
+		return rtw89_usb_switch_mode_ax(rtwdev);
+
+	return rtw89_usb_switch_mode_be(rtwdev);
+}
+
 int rtw89_usb_probe(struct usb_interface *intf,
 		    const struct usb_device_id *id)
 {
@@ -1091,6 +1182,13 @@ int rtw89_usb_probe(struct usb_interface *intf,
 		goto err_free_hw;
 	}
 
+	ret = rtw89_usb_switch_mode(rtwdev);
+	if (ret) {
+		/* Not a fail, but we do need to skip rtw89_core_register. */
+		ret = 0;
+		goto err_intf_deinit;
+	}
+
 	if (rtwusb->udev->speed == USB_SPEED_SUPER)
 		rtwdev->hci.dle_type = RTW89_HCI_DLE_TYPE_USB3;
 	else
-- 
2.54.0