This commit implements the complete programming sequence for ELPG
entry and exit.

 1. At ELPG entry, invokes tegra_xusb_padctl_enable_phy_sleepwalk()
    and tegra_xusb_padctl_enable_phy_wake() to configure XUSB PADCTL
    sleepwalk and wake detection circuits to maintain USB lines level
    and respond to wake events (wake-on-connect, wake-on-disconnect,
    device-initiated-wake).

 2. At ELPG exit, invokes tegra_xusb_padctl_disable_phy_sleepwalk()
    and tegra_xusb_padctl_disable_phy_wake() to disarm sleepwalk and
    wake detection circuits.

At runtime suspend, XUSB host controller can enter ELPG to reduce
power consumption. When XUSB PADCTL wake detection circuit detects
a wake event, an interrupt will be raised. xhci-tegra driver then
will invoke pm_runtime_resume() for xhci-tegra.

Runtime resume could also be triggered by protocol drivers, this is
the host-initiated-wake event. At runtime resume, xhci-tegra driver
brings XUSB host controller out of ELPG to handle the wake events.

The same ELPG enter/exit procedure will be performed for system
suspend/resume path so USB devices can remain connected across SC7.

Signed-off-by: JC Kuo <jc...@nvidia.com>
Acked-by: Thierry Reding <tred...@nvidia.com>
---
v7:
   add 'Acked-by: Thierry Reding <tred...@nvidia.com>'
v6:
   fix compiling warning: extra tokens at end of #ifdef directive
v5:
   avoid using xhci_get_rhub()
   protect ELPG routines with (CONFIG_PM || CONFIG_PM_SLEEP)
v4:
   reshuffle the code to avoid these pre-declarations
v3:
   use 'unsigned int' for PHY index
   remove unnecessary 'else'
   drop IRQF_TRIGGER_HIGH when invokes devm_request_threaded_irq()

 drivers/usb/host/xhci-tegra.c | 407 ++++++++++++++++++++++++++++++----
 1 file changed, 370 insertions(+), 37 deletions(-)

diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index 5b39a739f8f0..ce97ff054c68 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -15,9 +15,11 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/of_irq.h>
 #include <linux/phy/phy.h>
 #include <linux/phy/tegra/xusb.h>
 #include <linux/platform_device.h>
+#include <linux/usb/ch9.h>
 #include <linux/pm.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
@@ -224,6 +226,7 @@ struct tegra_xusb {
 
        int xhci_irq;
        int mbox_irq;
+       int padctl_irq;
 
        void __iomem *ipfs_base;
        void __iomem *fpci_base;
@@ -269,6 +272,7 @@ struct tegra_xusb {
                dma_addr_t phys;
        } fw;
 
+       bool suspended;
        struct tegra_xusb_context context;
 };
 
@@ -665,6 +669,9 @@ static irqreturn_t tegra_xusb_mbox_thread(int irq, void 
*data)
 
        mutex_lock(&tegra->lock);
 
+       if (pm_runtime_suspended(tegra->dev) || tegra->suspended)
+               goto out;
+
        value = fpci_readl(tegra, tegra->soc->mbox.data_out);
        tegra_xusb_mbox_unpack(&msg, value);
 
@@ -678,6 +685,7 @@ static irqreturn_t tegra_xusb_mbox_thread(int irq, void 
*data)
 
        tegra_xusb_mbox_handle(tegra, &msg);
 
+out:
        mutex_unlock(&tegra->lock);
        return IRQ_HANDLED;
 }
@@ -818,16 +826,6 @@ static void tegra_xusb_phy_disable(struct tegra_xusb 
*tegra)
        }
 }
 
-static int tegra_xusb_runtime_suspend(struct device *dev)
-{
-       return 0;
-}
-
-static int tegra_xusb_runtime_resume(struct device *dev)
-{
-       return 0;
-}
-
 #ifdef CONFIG_PM_SLEEP
 static int tegra_xusb_init_context(struct tegra_xusb *tegra)
 {
@@ -1128,6 +1126,24 @@ static int __tegra_xusb_enable_firmware_messages(struct 
tegra_xusb *tegra)
        return err;
 }
 
+static irqreturn_t tegra_xusb_padctl_irq(int irq, void *data)
+{
+       struct tegra_xusb *tegra = data;
+
+       mutex_lock(&tegra->lock);
+
+       if (tegra->suspended) {
+               mutex_unlock(&tegra->lock);
+               return IRQ_HANDLED;
+       }
+
+       mutex_unlock(&tegra->lock);
+
+       pm_runtime_resume(tegra->dev);
+
+       return IRQ_HANDLED;
+}
+
 static int tegra_xusb_enable_firmware_messages(struct tegra_xusb *tegra)
 {
        int err;
@@ -1251,6 +1267,52 @@ static void tegra_xhci_id_work(struct work_struct *work)
        }
 }
 
+#if IS_ENABLED(CONFIG_PM) || IS_ENABLED(CONFIG_PM_SLEEP)
+static bool is_usb2_otg_phy(struct tegra_xusb *tegra, unsigned int index)
+{
+       return (tegra->usbphy[index] != NULL);
+}
+
+static bool is_usb3_otg_phy(struct tegra_xusb *tegra, unsigned int index)
+{
+       struct tegra_xusb_padctl *padctl = tegra->padctl;
+       unsigned int i;
+       int port;
+
+       for (i = 0; i < tegra->num_usb_phys; i++) {
+               if (is_usb2_otg_phy(tegra, i)) {
+                       port = tegra_xusb_padctl_get_usb3_companion(padctl, i);
+                       if ((port >= 0) && (index == (unsigned int)port))
+                               return true;
+               }
+       }
+
+       return false;
+}
+
+static bool is_host_mode_phy(struct tegra_xusb *tegra, unsigned int phy_type, 
unsigned int index)
+{
+       if (strcmp(tegra->soc->phy_types[phy_type].name, "hsic") == 0)
+               return true;
+
+       if (strcmp(tegra->soc->phy_types[phy_type].name, "usb2") == 0) {
+               if (is_usb2_otg_phy(tegra, index))
+                       return ((index == tegra->otg_usb2_port) && 
tegra->host_mode);
+               else
+                       return true;
+       }
+
+       if (strcmp(tegra->soc->phy_types[phy_type].name, "usb3") == 0) {
+               if (is_usb3_otg_phy(tegra, index))
+                       return ((index == tegra->otg_usb3_port) && 
tegra->host_mode);
+               else
+                       return true;
+       }
+
+       return false;
+}
+#endif
+
 static int tegra_xusb_get_usb2_port(struct tegra_xusb *tegra,
                                              struct usb_phy *usbphy)
 {
@@ -1343,6 +1405,7 @@ static void tegra_xusb_deinit_usb_phy(struct tegra_xusb 
*tegra)
 static int tegra_xusb_probe(struct platform_device *pdev)
 {
        struct tegra_xusb *tegra;
+       struct device_node *np;
        struct resource *regs;
        struct xhci_hcd *xhci;
        unsigned int i, j, k;
@@ -1390,6 +1453,14 @@ static int tegra_xusb_probe(struct platform_device *pdev)
        if (IS_ERR(tegra->padctl))
                return PTR_ERR(tegra->padctl);
 
+       np = of_parse_phandle(pdev->dev.of_node, "nvidia,xusb-padctl", 0);
+       if (!np)
+               return -ENODEV;
+
+       tegra->padctl_irq = of_irq_get(np, 0);
+       if (tegra->padctl_irq <= 0)
+               return (tegra->padctl_irq == 0) ? -ENODEV : tegra->padctl_irq;
+
        tegra->host_clk = devm_clk_get(&pdev->dev, "xusb_host");
        if (IS_ERR(tegra->host_clk)) {
                err = PTR_ERR(tegra->host_clk);
@@ -1534,6 +1605,7 @@ static int tegra_xusb_probe(struct platform_device *pdev)
                goto put_powerdomains;
        }
 
+       tegra->hcd->skip_phy_initialization = 1;
        tegra->hcd->regs = tegra->regs;
        tegra->hcd->rsrc_start = regs->start;
        tegra->hcd->rsrc_len = resource_size(regs);
@@ -1616,12 +1688,6 @@ static int tegra_xusb_probe(struct platform_device *pdev)
                goto put_usb3;
        }
 
-       err = tegra_xusb_enable_firmware_messages(tegra);
-       if (err < 0) {
-               dev_err(&pdev->dev, "failed to enable messages: %d\n", err);
-               goto remove_usb3;
-       }
-
        err = devm_request_threaded_irq(&pdev->dev, tegra->mbox_irq,
                                        tegra_xusb_mbox_irq,
                                        tegra_xusb_mbox_thread, 0,
@@ -1631,12 +1697,36 @@ static int tegra_xusb_probe(struct platform_device 
*pdev)
                goto remove_usb3;
        }
 
+       err = devm_request_threaded_irq(&pdev->dev, tegra->padctl_irq, NULL, 
tegra_xusb_padctl_irq,
+                                       IRQF_ONESHOT, dev_name(&pdev->dev), 
tegra);
+       if (err < 0) {
+               dev_err(&pdev->dev, "failed to request padctl IRQ: %d\n", err);
+               goto remove_usb3;
+       }
+
+       err = tegra_xusb_enable_firmware_messages(tegra);
+       if (err < 0) {
+               dev_err(&pdev->dev, "failed to enable messages: %d\n", err);
+               goto remove_usb3;
+       }
+
        err = tegra_xusb_init_usb_phy(tegra);
        if (err < 0) {
                dev_err(&pdev->dev, "failed to init USB PHY: %d\n", err);
                goto remove_usb3;
        }
 
+       /* Enable wake for both USB 2.0 and USB 3.0 roothubs */
+       device_init_wakeup(&tegra->hcd->self.root_hub->dev, true);
+       device_init_wakeup(&xhci->shared_hcd->self.root_hub->dev, true);
+       device_init_wakeup(tegra->dev, true);
+
+       pm_runtime_use_autosuspend(tegra->dev);
+       pm_runtime_set_autosuspend_delay(tegra->dev, 2000);
+       pm_runtime_mark_last_busy(tegra->dev);
+       pm_runtime_set_active(tegra->dev);
+       pm_runtime_enable(tegra->dev);
+
        return 0;
 
 remove_usb3:
@@ -1672,6 +1762,7 @@ static int tegra_xusb_remove(struct platform_device *pdev)
 
        tegra_xusb_deinit_usb_phy(tegra);
 
+       pm_runtime_get_sync(&pdev->dev);
        usb_remove_hcd(xhci->shared_hcd);
        usb_put_hcd(xhci->shared_hcd);
        xhci->shared_hcd = NULL;
@@ -1681,8 +1772,8 @@ static int tegra_xusb_remove(struct platform_device *pdev)
        dma_free_coherent(&pdev->dev, tegra->fw.size, tegra->fw.virt,
                          tegra->fw.phys);
 
-       pm_runtime_put_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
+       pm_runtime_put(&pdev->dev);
 
        tegra_xusb_powergate_partitions(tegra);
 
@@ -1696,7 +1787,7 @@ static int tegra_xusb_remove(struct platform_device *pdev)
        return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
+#if IS_ENABLED(CONFIG_PM) || IS_ENABLED(CONFIG_PM_SLEEP)
 static bool xhci_hub_ports_suspended(struct xhci_hub *hub)
 {
        struct device *dev = hub->hcd->self.controller;
@@ -1722,9 +1813,17 @@ static bool xhci_hub_ports_suspended(struct xhci_hub 
*hub)
 static int tegra_xusb_check_ports(struct tegra_xusb *tegra)
 {
        struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
+       struct xhci_bus_state *bus_state = &xhci->usb2_rhub.bus_state;
        unsigned long flags;
        int err = 0;
 
+       if (bus_state->bus_suspended) {
+               /* xusb_hub_suspend() has just directed one or more USB2 port(s)
+                * to U3 state, it takes 3ms to enter U3.
+                */
+               usleep_range(3000, 4000);
+       }
+
        spin_lock_irqsave(&xhci->lock, flags);
 
        if (!xhci_hub_ports_suspended(&xhci->usb2_rhub) ||
@@ -1770,45 +1869,186 @@ static void tegra_xusb_restore_context(struct 
tegra_xusb *tegra)
        }
 }
 
-static int tegra_xusb_enter_elpg(struct tegra_xusb *tegra, bool wakeup)
+static enum usb_device_speed tegra_xhci_portsc_to_speed(struct tegra_xusb 
*tegra, u32 portsc)
+{
+       if (DEV_LOWSPEED(portsc))
+               return USB_SPEED_LOW;
+
+       if (DEV_HIGHSPEED(portsc))
+               return USB_SPEED_HIGH;
+
+       if (DEV_FULLSPEED(portsc))
+               return USB_SPEED_FULL;
+
+       if (DEV_SUPERSPEED_ANY(portsc))
+               return USB_SPEED_SUPER;
+
+       return USB_SPEED_UNKNOWN;
+}
+
+static void tegra_xhci_enable_phy_sleepwalk_wake(struct tegra_xusb *tegra)
 {
+       struct tegra_xusb_padctl *padctl = tegra->padctl;
        struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
+       enum usb_device_speed speed;
+       struct phy *phy;
+       unsigned int index, offset;
+       unsigned int i, j, k;
+       struct xhci_hub *rhub;
+       u32 portsc;
+
+       for (i = 0, k = 0; i < tegra->soc->num_types; i++) {
+               if (strcmp(tegra->soc->phy_types[i].name, "usb3") == 0)
+                       rhub = &xhci->usb3_rhub;
+               else
+                       rhub = &xhci->usb2_rhub;
+
+               if (strcmp(tegra->soc->phy_types[i].name, "hsic") == 0)
+                       offset = tegra->soc->ports.usb2.count;
+               else
+                       offset = 0;
+
+               for (j = 0; j < tegra->soc->phy_types[i].num; j++) {
+                       phy = tegra->phys[k++];
+
+                       if (!phy)
+                               continue;
+
+                       index = j + offset;
+
+                       if (index >= rhub->num_ports)
+                               continue;
+
+                       if (!is_host_mode_phy(tegra, i, j))
+                               continue;
+
+                       portsc = readl(rhub->ports[index]->addr);
+                       speed = tegra_xhci_portsc_to_speed(tegra, portsc);
+                       tegra_xusb_padctl_enable_phy_sleepwalk(padctl, phy, 
speed);
+                       tegra_xusb_padctl_enable_phy_wake(padctl, phy);
+               }
+       }
+}
+
+static void tegra_xhci_disable_phy_wake(struct tegra_xusb *tegra)
+{
+       struct tegra_xusb_padctl *padctl = tegra->padctl;
+       unsigned int i;
+
+       for (i = 0; i < tegra->num_phys; i++) {
+               if (!tegra->phys[i])
+                       continue;
+
+               tegra_xusb_padctl_disable_phy_wake(padctl, tegra->phys[i]);
+       }
+}
+
+static void tegra_xhci_disable_phy_sleepwalk(struct tegra_xusb *tegra)
+{
+       struct tegra_xusb_padctl *padctl = tegra->padctl;
+       unsigned int i;
+
+       for (i = 0; i < tegra->num_phys; i++) {
+               if (!tegra->phys[i])
+                       continue;
+
+               tegra_xusb_padctl_disable_phy_sleepwalk(padctl, tegra->phys[i]);
+       }
+}
+
+static int tegra_xusb_enter_elpg(struct tegra_xusb *tegra, bool runtime)
+{
+       struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
+       struct device *dev = tegra->dev;
+       bool wakeup = runtime ? true : device_may_wakeup(dev);
+       unsigned int i;
        int err;
+       u32 usbcmd;
+
+       dev_dbg(dev, "entering ELPG\n");
+
+       usbcmd = readl(&xhci->op_regs->command);
+       usbcmd &= ~CMD_EIE;
+       writel(usbcmd, &xhci->op_regs->command);
 
        err = tegra_xusb_check_ports(tegra);
        if (err < 0) {
                dev_err(tegra->dev, "not all ports suspended: %d\n", err);
-               return err;
+               goto out;
        }
 
        err = xhci_suspend(xhci, wakeup);
        if (err < 0) {
                dev_err(tegra->dev, "failed to suspend XHCI: %d\n", err);
-               return err;
+               goto out;
        }
 
        tegra_xusb_save_context(tegra);
-       tegra_xusb_phy_disable(tegra);
+
+       if (wakeup)
+               tegra_xhci_enable_phy_sleepwalk_wake(tegra);
+
+       tegra_xusb_powergate_partitions(tegra);
+
+       for (i = 0; i < tegra->num_phys; i++) {
+               if (!tegra->phys[i])
+                       continue;
+
+               phy_power_off(tegra->phys[i]);
+               if (!wakeup)
+                       phy_exit(tegra->phys[i]);
+       }
+
        tegra_xusb_clk_disable(tegra);
 
-       return 0;
+out:
+       if (!err)
+               dev_dbg(tegra->dev, "entering ELPG done\n");
+       else {
+               usbcmd = readl(&xhci->op_regs->command);
+               usbcmd |= CMD_EIE;
+               writel(usbcmd, &xhci->op_regs->command);
+
+               dev_dbg(tegra->dev, "entering ELPG failed\n");
+               pm_runtime_mark_last_busy(tegra->dev);
+       }
+
+       return err;
 }
 
-static int tegra_xusb_exit_elpg(struct tegra_xusb *tegra, bool wakeup)
+static int tegra_xusb_exit_elpg(struct tegra_xusb *tegra, bool runtime)
 {
        struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
+       struct device *dev = tegra->dev;
+       bool wakeup = runtime ? true : device_may_wakeup(dev);
+       unsigned int i;
+       u32 usbcmd;
        int err;
 
+       dev_dbg(dev, "exiting ELPG\n");
+       pm_runtime_mark_last_busy(tegra->dev);
+
        err = tegra_xusb_clk_enable(tegra);
        if (err < 0) {
                dev_err(tegra->dev, "failed to enable clocks: %d\n", err);
-               return err;
+               goto out;
        }
 
-       err = tegra_xusb_phy_enable(tegra);
-       if (err < 0) {
-               dev_err(tegra->dev, "failed to enable PHYs: %d\n", err);
-               goto disable_clk;
+       err = tegra_xusb_unpowergate_partitions(tegra);
+       if (err)
+               goto disable_clks;
+
+       if (wakeup)
+               tegra_xhci_disable_phy_wake(tegra);
+
+       for (i = 0; i < tegra->num_phys; i++) {
+               if (!tegra->phys[i])
+                       continue;
+
+               if (!wakeup)
+                       phy_init(tegra->phys[i]);
+
+               phy_power_on(tegra->phys[i]);
        }
 
        tegra_xusb_config(tegra);
@@ -1826,31 +2066,79 @@ static int tegra_xusb_exit_elpg(struct tegra_xusb 
*tegra, bool wakeup)
                goto disable_phy;
        }
 
-       err = xhci_resume(xhci, true);
+       if (wakeup)
+               tegra_xhci_disable_phy_sleepwalk(tegra);
+
+       err = xhci_resume(xhci, 0);
        if (err < 0) {
                dev_err(tegra->dev, "failed to resume XHCI: %d\n", err);
                goto disable_phy;
        }
 
-       return 0;
+       usbcmd = readl(&xhci->op_regs->command);
+       usbcmd |= CMD_EIE;
+       writel(usbcmd, &xhci->op_regs->command);
+
+       goto out;
 
 disable_phy:
-       tegra_xusb_phy_disable(tegra);
-disable_clk:
+       for (i = 0; i < tegra->num_phys; i++) {
+               if (!tegra->phys[i])
+                       continue;
+
+               phy_power_off(tegra->phys[i]);
+               if (!wakeup)
+                       phy_exit(tegra->phys[i]);
+       }
+       tegra_xusb_powergate_partitions(tegra);
+disable_clks:
        tegra_xusb_clk_disable(tegra);
+out:
+       if (!err)
+               dev_dbg(dev, "exiting ELPG done\n");
+       else
+               dev_dbg(dev, "exiting ELPG failed\n");
+
        return err;
 }
 
 static int tegra_xusb_suspend(struct device *dev)
 {
        struct tegra_xusb *tegra = dev_get_drvdata(dev);
-       bool wakeup = device_may_wakeup(dev);
        int err;
 
        synchronize_irq(tegra->mbox_irq);
 
        mutex_lock(&tegra->lock);
-       err = tegra_xusb_enter_elpg(tegra, wakeup);
+
+       if (pm_runtime_suspended(dev)) {
+               err = tegra_xusb_exit_elpg(tegra, true);
+               if (err < 0)
+                       goto out;
+       }
+
+       err = tegra_xusb_enter_elpg(tegra, false);
+       if (err < 0) {
+               if (pm_runtime_suspended(dev)) {
+                       pm_runtime_disable(dev);
+                       pm_runtime_set_active(dev);
+                       pm_runtime_enable(dev);
+               }
+
+               goto out;
+       }
+
+out:
+       if (!err) {
+               tegra->suspended = true;
+               pm_runtime_disable(dev);
+
+               if (device_may_wakeup(dev)) {
+                       if (enable_irq_wake(tegra->padctl_irq))
+                               dev_err(dev, "failed to enable padctl wakes\n");
+               }
+       }
+
        mutex_unlock(&tegra->lock);
 
        return err;
@@ -1859,11 +2147,56 @@ static int tegra_xusb_suspend(struct device *dev)
 static int tegra_xusb_resume(struct device *dev)
 {
        struct tegra_xusb *tegra = dev_get_drvdata(dev);
-       bool wakeup = device_may_wakeup(dev);
        int err;
 
        mutex_lock(&tegra->lock);
-       err = tegra_xusb_exit_elpg(tegra, wakeup);
+
+       if (!tegra->suspended) {
+               mutex_unlock(&tegra->lock);
+               return 0;
+       }
+
+       err = tegra_xusb_exit_elpg(tegra, false);
+       if (err < 0) {
+               mutex_unlock(&tegra->lock);
+               return err;
+       }
+
+       if (device_may_wakeup(dev)) {
+               if (disable_irq_wake(tegra->padctl_irq))
+                       dev_err(dev, "failed to disable padctl wakes\n");
+       }
+       tegra->suspended = false;
+       mutex_unlock(&tegra->lock);
+
+       pm_runtime_set_active(dev);
+       pm_runtime_enable(dev);
+
+       return 0;
+}
+#endif
+
+#ifdef CONFIG_PM
+static int tegra_xusb_runtime_suspend(struct device *dev)
+{
+       struct tegra_xusb *tegra = dev_get_drvdata(dev);
+       int ret;
+
+       synchronize_irq(tegra->mbox_irq);
+       mutex_lock(&tegra->lock);
+       ret = tegra_xusb_enter_elpg(tegra, true);
+       mutex_unlock(&tegra->lock);
+
+       return ret;
+}
+
+static int tegra_xusb_runtime_resume(struct device *dev)
+{
+       struct tegra_xusb *tegra = dev_get_drvdata(dev);
+       int err;
+
+       mutex_lock(&tegra->lock);
+       err = tegra_xusb_exit_elpg(tegra, true);
        mutex_unlock(&tegra->lock);
 
        return err;
-- 
2.25.1

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