[PATCH v3 8/8] phy: exynos5-usbdrd: allow DWC3 runtime suspend with UDC bound (E850+)

[André Draszik]

To make USB runtime suspend work when a UDC has been bound, the phy
needs to inform the USBDRD controller (DWC3) that Vbus and bvalid are
gone, so that it can in turn raise the respective gadget interrupt with
event == DWC3_DEVICE_EVENT_DISCONNECT, which will cause the USB stack
to clean up, allowing DWC3 to enter runtime suspend.

On e850 and gs101 this isn't working, as the respective signals are not
directly connected, and instead this driver uses override bits in the
PHY IP to set those signals. It currently forcefully sets them to 'on',
so the above mentioned interrupt will not be raised, preventing runtime
suspend.

To detect that state, update this driver to act on the TCPC's
orientation signal - when orientation == NONE, Vbus is gone and we can
clear the respective bits. Similarly, for other orientation values we
re-enable them.

This makes runtime suspend work on platforms with a TCPC (like Pixel6),
while keeping compatibility with platforms without (e850-96).

With runtime suspend working, USB-C cable orientation detection now
also fully works on such platforms, and the link comes up as Superspeed
as expected irrespective of the cable orientation and whether UDC /
gadget are configured and active.

Signed-off-by: André Draszik <andre.draszik at linaro.org>

---
v3:
* update exynos5_usbdrd_orien_sw_set() to not test against previous
  orientation
---
 drivers/phy/samsung/phy-exynos5-usbdrd.c | 50 +++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 8 deletions(-)

diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c
index 6dcc3c80c1d2..ae42e299ba42 100644
--- a/drivers/phy/samsung/phy-exynos5-usbdrd.c
+++ b/drivers/phy/samsung/phy-exynos5-usbdrd.c
@@ -1137,13 +1137,15 @@ static void exynos850_usbdrd_utmi_init(struct exynos5_usbdrd_phy *phy_drd)
 	reg |= LINKCTRL_BUS_FILTER_BYPASS(0xf);
 	writel(reg, regs_base + EXYNOS850_DRD_LINKCTRL);
 
-	reg = readl(regs_base + EXYNOS850_DRD_UTMI);
-	reg |= UTMI_FORCE_BVALID | UTMI_FORCE_VBUSVALID;
-	writel(reg, regs_base + EXYNOS850_DRD_UTMI);
-
-	reg = readl(regs_base + EXYNOS850_DRD_HSP);
-	reg |= HSP_VBUSVLDEXT | HSP_VBUSVLDEXTSEL;
-	writel(reg, regs_base + EXYNOS850_DRD_HSP);
+	if (!phy_drd->sw) {
+		reg = readl(regs_base + EXYNOS850_DRD_UTMI);
+		reg |= UTMI_FORCE_BVALID | UTMI_FORCE_VBUSVALID;
+		writel(reg, regs_base + EXYNOS850_DRD_UTMI);
+
+		reg = readl(regs_base + EXYNOS850_DRD_HSP);
+		reg |= HSP_VBUSVLDEXT | HSP_VBUSVLDEXTSEL;
+		writel(reg, regs_base + EXYNOS850_DRD_HSP);
+	}
 
 	reg = readl(regs_base + EXYNOS850_DRD_SSPPLLCTL);
 	reg &= ~SSPPLLCTL_FSEL;
@@ -1407,9 +1409,41 @@ static int exynos5_usbdrd_orien_sw_set(struct typec_switch_dev *sw,
 				       enum typec_orientation orientation)
 {
 	struct exynos5_usbdrd_phy *phy_drd = typec_switch_get_drvdata(sw);
+	int ret;
+
+	ret = clk_bulk_prepare_enable(phy_drd->drv_data->n_clks, phy_drd->clks);
+	if (ret) {
+		dev_err(phy_drd->dev, "Failed to enable PHY clocks(s)\n");
+		return ret;
+	}
+
+	scoped_guard(mutex, &phy_drd->phy_mutex) {
+		void __iomem * const regs_base = phy_drd->reg_phy;
+		unsigned int reg;
+
+		if (orientation == TYPEC_ORIENTATION_NONE) {
+			reg = readl(regs_base + EXYNOS850_DRD_UTMI);
+			reg &= ~(UTMI_FORCE_VBUSVALID | UTMI_FORCE_BVALID);
+			writel(reg, regs_base +  EXYNOS850_DRD_UTMI);
+
+			reg = readl(regs_base + EXYNOS850_DRD_HSP);
+			reg |= HSP_VBUSVLDEXTSEL;
+			reg &= ~HSP_VBUSVLDEXT;
+			writel(reg, regs_base + EXYNOS850_DRD_HSP);
+		} else {
+			reg = readl(regs_base + EXYNOS850_DRD_UTMI);
+			reg |= UTMI_FORCE_VBUSVALID | UTMI_FORCE_BVALID;
+			writel(reg, regs_base +  EXYNOS850_DRD_UTMI);
+
+			reg = readl(regs_base + EXYNOS850_DRD_HSP);
+			reg |= HSP_VBUSVLDEXTSEL | HSP_VBUSVLDEXT;
+			writel(reg, regs_base + EXYNOS850_DRD_HSP);
+		}
 
-	scoped_guard(mutex, &phy_drd->phy_mutex)
 		phy_drd->orientation = orientation;
+	}
+
+	clk_bulk_disable(phy_drd->drv_data->n_clks, phy_drd->clks);
 
 	return 0;
 }

-- 
2.47.0.338.g60cca15819-goog