[PATCH v1 2/8] usb: phy: tegra: Support waking up from a low power mode

[Dmitry Osipenko <digetx@gmail.com>]

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 <mattmerhar@protonmail.com>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/usb/phy/phy-tegra-usb.c   | 79 ++++++++++++++++++++++++++++---
 include/linux/usb/tegra_usb_phy.h |  2 +
 2 files changed, 75 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
index cee9c9dbb775..ed5f6611b36a 100644
--- a/drivers/usb/phy/phy-tegra-usb.c
+++ b/drivers/usb/phy/phy-tegra-usb.c
@@ -45,6 +45,7 @@
 #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)
@@ -56,6 +57,9 @@
 #define   USB_SUSP_SET				BIT(14)
 #define   USB_WAKEUP_DEBOUNCE_COUNT(x)		(((x) & 0x7) << 16)
 
+#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)
 #define   USB1_VBUS_SENSE_CTL_MASK		(3 << 1)
@@ -334,6 +338,11 @@ static int utmip_pad_power_on(struct tegra_usb_phy *phy)
 		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);
@@ -359,6 +368,17 @@ static int utmip_pad_power_off(struct tegra_usb_phy *phy)
 		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) {
 		val = readl_relaxed(base + UTMIP_BIAS_CFG0);
 		val |= UTMIP_OTGPD | UTMIP_BIASPD;
@@ -503,11 +523,19 @@ static int utmi_phy_power_on(struct tegra_usb_phy *phy)
 		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 + UTMIP_BAT_CHRG_CFG0);
 		val &= ~UTMIP_PD_CHRG;
 		writel_relaxed(val, base + UTMIP_BAT_CHRG_CFG0);
@@ -605,31 +633,51 @@ static int utmi_phy_power_off(struct tegra_usb_phy *phy)
 
 	utmi_phy_clk_disable(phy);
 
-	if (phy->mode == USB_DR_MODE_PERIPHERAL) {
-		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);
-		writel_relaxed(val, base + USB_SUSP_CTRL);
-	}
+	/* PHY won't resume if reset is asserted */
+	if (phy->wakeup_enabled)
+		goto chrg_cfg0;
 
 	val = readl_relaxed(base + USB_SUSP_CTRL);
 	val |= UTMIP_RESET;
 	writel_relaxed(val, base + USB_SUSP_CTRL);
 
+chrg_cfg0:
 	val = readl_relaxed(base + UTMIP_BAT_CHRG_CFG0);
 	val |= UTMIP_PD_CHRG;
 	writel_relaxed(val, base + UTMIP_BAT_CHRG_CFG0);
 
+	if (phy->wakeup_enabled)
+		goto xcvr_cfg1;
+
 	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);
 
+xcvr_cfg1:
 	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);
+		}
+	}
+
 	return utmip_pad_power_off(phy);
 }
 
@@ -765,6 +813,15 @@ static int ulpi_phy_power_off(struct tegra_usb_phy *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;
 }
 
@@ -827,6 +884,15 @@ static void tegra_usb_phy_shutdown(struct usb_phy *u_phy)
 	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)
 {
 	struct tegra_usb_phy *phy = to_tegra_usb_phy(u_phy);
@@ -1198,6 +1264,7 @@ static int tegra_usb_phy_probe(struct platform_device *pdev)
 	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);
diff --git a/include/linux/usb/tegra_usb_phy.h b/include/linux/usb/tegra_usb_phy.h
index c29d1b4c9381..fd1c9f6a4e37 100644
--- a/include/linux/usb/tegra_usb_phy.h
+++ b/include/linux/usb/tegra_usb_phy.h
@@ -79,6 +79,8 @@ struct tegra_usb_phy {
 	bool is_ulpi_phy;
 	struct gpio_desc *reset_gpio;
 	struct reset_control *pad_rst;
+	bool wakeup_enabled;
+	bool pad_wakeup;
 	bool powered_on;
 };
 
-- 
2.29.2