usb: phy: tegra: Support waking up from a low power mode

Support programming of waking up from a low power mode by implementing the
generic set_wakeup() callback of the USB PHY API.

Tested-by: Matt Merhar <[e-mail]>
Tested-by: Nicolas Chauvet <[e-mail]>
Tested-by: Peter Geis <[e-mail]>
Tested-by: Ion Agorria <[e-mail]>
Acked-by: Thierry Reding <[e-mail]>
Acked-by: Peter Chen <[e-mail]>
Signed-off-by: Dmitry Osipenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/phy/phy-tegra-usb.c

···
 #define TEGRA_PORTSC1_RWC_BITS	(PORT_CSC | PORT_PEC | PORT_OCC)
 
 #define USB_SUSP_CTRL				0x400
+#define   USB_WAKE_ON_RESUME_EN			BIT(2)
 #define   USB_WAKE_ON_CNNT_EN_DEV		BIT(3)
 #define   USB_WAKE_ON_DISCON_EN_DEV		BIT(4)
 #define   USB_SUSP_CLR				BIT(5)
···
 #define   ULPI_PHY_ENABLE			BIT(13)
 #define   USB_SUSP_SET				BIT(14)
 #define   USB_WAKEUP_DEBOUNCE_COUNT(x)		(((x) & 0x7) << 16)
+
+#define USB_PHY_VBUS_SENSORS			0x404
+#define   B_SESS_VLD_WAKEUP_EN			BIT(6)
+#define   B_VBUS_VLD_WAKEUP_EN			BIT(14)
+#define   A_SESS_VLD_WAKEUP_EN			BIT(22)
+#define   A_VBUS_VLD_WAKEUP_EN			BIT(30)
+
+#define USB_PHY_VBUS_WAKEUP_ID			0x408
+#define   VBUS_WAKEUP_WAKEUP_EN			BIT(30)
 
 #define USB1_LEGACY_CTRL			0x410
 #define   USB1_NO_LEGACY_MODE			BIT(0)
···
 		writel_relaxed(val, base + UTMIP_BIAS_CFG0);
 	}
 
+	if (phy->pad_wakeup) {
+		phy->pad_wakeup = false;
+		utmip_pad_count--;
+	}
+
 	spin_unlock(&utmip_pad_lock);
 
 	clk_disable_unprepare(phy->pad_clk);
···
 		dev_err(phy->u_phy.dev, "UTMIP pad already powered off\n");
 		ret = -EINVAL;
 		goto ulock;
+	}
+
+	/*
+	 * In accordance to TRM, OTG and Bias pad circuits could be turned off
+	 * to save power if wake is enabled, but the VBUS-change detection
+	 * method is board-specific and these circuits may need to be enabled
+	 * to generate wakeup event, hence we will just keep them both enabled.
+	 */
+	if (phy->wakeup_enabled) {
+		phy->pad_wakeup = true;
+		utmip_pad_count++;
 	}
 
 	if (--utmip_pad_count == 0) {
···
 		writel_relaxed(val, base + UTMIP_PLL_CFG1);
 	}
 
+	val = readl_relaxed(base + USB_SUSP_CTRL);
+	val &= ~USB_WAKE_ON_RESUME_EN;
+	writel_relaxed(val, base + USB_SUSP_CTRL);
+
 	if (phy->mode == USB_DR_MODE_PERIPHERAL) {
 		val = readl_relaxed(base + USB_SUSP_CTRL);
 		val &= ~(USB_WAKE_ON_CNNT_EN_DEV | USB_WAKE_ON_DISCON_EN_DEV);
 		writel_relaxed(val, base + USB_SUSP_CTRL);
+
+		val = readl_relaxed(base + USB_PHY_VBUS_WAKEUP_ID);
+		val &= ~VBUS_WAKEUP_WAKEUP_EN;
+		writel_relaxed(val, base + USB_PHY_VBUS_WAKEUP_ID);
+
+		val = readl_relaxed(base + USB_PHY_VBUS_SENSORS);
+		val &= ~(A_VBUS_VLD_WAKEUP_EN | A_SESS_VLD_WAKEUP_EN);
+		val &= ~(B_VBUS_VLD_WAKEUP_EN | B_SESS_VLD_WAKEUP_EN);
+		writel_relaxed(val, base + USB_PHY_VBUS_SENSORS);
 
 		val = readl_relaxed(base + UTMIP_BAT_CHRG_CFG0);
 		val &= ~UTMIP_PD_CHRG;
···
 
 	utmi_phy_clk_disable(phy);
 
-	if (phy->mode == USB_DR_MODE_PERIPHERAL) {
+	/* PHY won't resume if reset is asserted */
+	if (!phy->wakeup_enabled) {
 		val = readl_relaxed(base + USB_SUSP_CTRL);
-		val &= ~USB_WAKEUP_DEBOUNCE_COUNT(~0);
-		val |= USB_WAKE_ON_CNNT_EN_DEV | USB_WAKEUP_DEBOUNCE_COUNT(5);
+		val |= UTMIP_RESET;
 		writel_relaxed(val, base + USB_SUSP_CTRL);
 	}
-
-	val = readl_relaxed(base + USB_SUSP_CTRL);
-	val |= UTMIP_RESET;
-	writel_relaxed(val, base + USB_SUSP_CTRL);
 
 	val = readl_relaxed(base + UTMIP_BAT_CHRG_CFG0);
 	val |= UTMIP_PD_CHRG;
 	writel_relaxed(val, base + UTMIP_BAT_CHRG_CFG0);
 
-	val = readl_relaxed(base + UTMIP_XCVR_CFG0);
-	val |= UTMIP_FORCE_PD_POWERDOWN | UTMIP_FORCE_PD2_POWERDOWN |
-	       UTMIP_FORCE_PDZI_POWERDOWN;
-	writel_relaxed(val, base + UTMIP_XCVR_CFG0);
+	if (!phy->wakeup_enabled) {
+		val = readl_relaxed(base + UTMIP_XCVR_CFG0);
+		val |= UTMIP_FORCE_PD_POWERDOWN | UTMIP_FORCE_PD2_POWERDOWN |
+		       UTMIP_FORCE_PDZI_POWERDOWN;
+		writel_relaxed(val, base + UTMIP_XCVR_CFG0);
+	}
 
 	val = readl_relaxed(base + UTMIP_XCVR_CFG1);
 	val |= UTMIP_FORCE_PDDISC_POWERDOWN | UTMIP_FORCE_PDCHRP_POWERDOWN |
 	       UTMIP_FORCE_PDDR_POWERDOWN;
 	writel_relaxed(val, base + UTMIP_XCVR_CFG1);
+
+	if (phy->wakeup_enabled) {
+		val = readl_relaxed(base + USB_SUSP_CTRL);
+		val &= ~USB_WAKEUP_DEBOUNCE_COUNT(~0);
+		val |= USB_WAKEUP_DEBOUNCE_COUNT(5);
+		val |= USB_WAKE_ON_RESUME_EN;
+		writel_relaxed(val, base + USB_SUSP_CTRL);
+
+		/*
+		 * Ask VBUS sensor to generate wake event once cable is
+		 * connected.
+		 */
+		if (phy->mode == USB_DR_MODE_PERIPHERAL) {
+			val = readl_relaxed(base + USB_PHY_VBUS_WAKEUP_ID);
+			val |= VBUS_WAKEUP_WAKEUP_EN;
+			writel_relaxed(val, base + USB_PHY_VBUS_WAKEUP_ID);
+
+			val = readl_relaxed(base + USB_PHY_VBUS_SENSORS);
+			val |= A_VBUS_VLD_WAKEUP_EN;
+			writel_relaxed(val, base + USB_PHY_VBUS_SENSORS);
+		}
+	}
 
 	return utmip_pad_power_off(phy);
 }
···
 	usleep_range(5000, 6000);
 	clk_disable_unprepare(phy->clk);
 
+	/*
+	 * Wakeup currently unimplemented for ULPI, thus PHY needs to be
+	 * force-resumed.
+	 */
+	if (WARN_ON_ONCE(phy->wakeup_enabled)) {
+		ulpi_phy_power_on(phy);
+		return -EOPNOTSUPP;
+	}
+
 	return 0;
 }
 
···
 	clk_disable_unprepare(phy->pll_u);
 
 	phy->freq = NULL;
+}
+
+static int tegra_usb_phy_set_wakeup(struct usb_phy *u_phy, bool enable)
+{
+	struct tegra_usb_phy *phy = to_tegra_usb_phy(u_phy);
+
+	phy->wakeup_enabled = enable;
+
+	return 0;
 }
 
 static int tegra_usb_phy_set_suspend(struct usb_phy *u_phy, int suspend)
···
 	tegra_phy->u_phy.dev = &pdev->dev;
 	tegra_phy->u_phy.init = tegra_usb_phy_init;
 	tegra_phy->u_phy.shutdown = tegra_usb_phy_shutdown;
+	tegra_phy->u_phy.set_wakeup = tegra_usb_phy_set_wakeup;
 	tegra_phy->u_phy.set_suspend = tegra_usb_phy_set_suspend;
 
 	platform_set_drvdata(pdev, tegra_phy);

include/linux/usb/tegra_usb_phy.h

···
 	bool is_ulpi_phy;
 	struct gpio_desc *reset_gpio;
 	struct reset_control *pad_rst;
+	bool wakeup_enabled;
+	bool pad_wakeup;
 	bool powered_on;
 };