bus: mhi: pci_generic: Add support for runtime PM

When the device is idle it is possible to move it into the lowest MHI
PM state (M3). In that mode, all MHI operations are suspended and the
PCI device can be safely put into PCI D3 state.

The device is then resumed from D3/M3 either because of host initiated
MHI operation (e.g. buffer TX) or because the device (modem) has
triggered wake-up via PME feature (e.g. on incoming data).

Same procedures can be used for system wide or runtime suspend/resume.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614971808-22156-6-git-send-email-loic.poulain@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
index ea46dda0ebf29b60434f163cc51a253e0acd2881..5cf44bcfe0400925c84ebc51f425297241f4c015 100644 (file)
--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -14,6 +14,7 @@
 #include <linux/mhi.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/pm_runtime.h>
 #include <linux/timer.h>
 #include <linux/workqueue.h>
 
@@ -274,6 +275,7 @@ MODULE_DEVICE_TABLE(pci, mhi_pci_id_table);
 
 enum mhi_pci_device_status {
        MHI_PCI_DEV_STARTED,
+       MHI_PCI_DEV_SUSPENDED,
 };
 
 struct mhi_pci_device {
@@ -307,6 +309,10 @@ static void mhi_pci_status_cb(struct mhi_controller *mhi_cntrl,
        case MHI_CB_FATAL_ERROR:
        case MHI_CB_SYS_ERROR:
                dev_warn(&pdev->dev, "firmware crashed (%u)\n", cb);
+               pm_runtime_forbid(&pdev->dev);
+               break;
+       case MHI_CB_EE_MISSION_MODE:
+               pm_runtime_allow(&pdev->dev);
                break;
        default:
                break;
@@ -428,13 +434,19 @@ static int mhi_pci_get_irqs(struct mhi_controller *mhi_cntrl,
 
 static int mhi_pci_runtime_get(struct mhi_controller *mhi_cntrl)
 {
-       /* no PM for now */
-       return 0;
+       /* The runtime_get() MHI callback means:
+        *    Do whatever is requested to leave M3.
+        */
+       return pm_runtime_get(mhi_cntrl->cntrl_dev);
 }
 
 static void mhi_pci_runtime_put(struct mhi_controller *mhi_cntrl)
 {
-       /* no PM for now */
+       /* The runtime_put() MHI callback means:
+        *    Device can be moved in M3 state.
+        */
+       pm_runtime_mark_last_busy(mhi_cntrl->cntrl_dev);
+       pm_runtime_put(mhi_cntrl->cntrl_dev);
 }
 
 static void mhi_pci_recovery_work(struct work_struct *work)
@@ -448,6 +460,7 @@ static void mhi_pci_recovery_work(struct work_struct *work)
        dev_warn(&pdev->dev, "device recovery started\n");
 
        del_timer(&mhi_pdev->health_check_timer);
+       pm_runtime_forbid(&pdev->dev);
 
        /* Clean up MHI state */
        if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
@@ -455,7 +468,6 @@ static void mhi_pci_recovery_work(struct work_struct *work)
                mhi_unprepare_after_power_down(mhi_cntrl);
        }
 
-       /* Check if we can recover without full reset */
        pci_set_power_state(pdev, PCI_D0);
        pci_load_saved_state(pdev, mhi_pdev->pci_state);
        pci_restore_state(pdev);
@@ -489,6 +501,10 @@ static void health_check(struct timer_list *t)
        struct mhi_pci_device *mhi_pdev = from_timer(mhi_pdev, t, health_check_timer);
        struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
 
+       if (!test_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status) ||
+                       test_bit(MHI_PCI_DEV_SUSPENDED, &mhi_pdev->status))
+               return;
+
        if (!mhi_pci_is_alive(mhi_cntrl)) {
                dev_err(mhi_cntrl->cntrl_dev, "Device died\n");
                queue_work(system_long_wq, &mhi_pdev->recovery_work);
@@ -576,6 +592,14 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
        /* start health check */
        mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);
 
+       /* Only allow runtime-suspend if PME capable (for wakeup) */
+       if (pci_pme_capable(pdev, PCI_D3hot)) {
+               pm_runtime_set_autosuspend_delay(&pdev->dev, 2000);
+               pm_runtime_use_autosuspend(&pdev->dev);
+               pm_runtime_mark_last_busy(&pdev->dev);
+               pm_runtime_put_noidle(&pdev->dev);
+       }
+
        return 0;
 
 err_unprepare:
@@ -599,6 +623,10 @@ static void mhi_pci_remove(struct pci_dev *pdev)
                mhi_unprepare_after_power_down(mhi_cntrl);
        }
 
+       /* balancing probe put_noidle */
+       if (pci_pme_capable(pdev, PCI_D3hot))
+               pm_runtime_get_noresume(&pdev->dev);
+
        mhi_unregister_controller(mhi_cntrl);
 }
 
@@ -709,31 +737,48 @@ static const struct pci_error_handlers mhi_pci_err_handler = {
        .reset_done = mhi_pci_reset_done,
 };
 
-static int  __maybe_unused mhi_pci_suspend(struct device *dev)
+static int  __maybe_unused mhi_pci_runtime_suspend(struct device *dev)
 {
        struct pci_dev *pdev = to_pci_dev(dev);
        struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
        struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
+       int err;
+
+       if (test_and_set_bit(MHI_PCI_DEV_SUSPENDED, &mhi_pdev->status))
+               return 0;
 
        del_timer(&mhi_pdev->health_check_timer);
        cancel_work_sync(&mhi_pdev->recovery_work);
 
+       if (!test_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status) ||
+                       mhi_cntrl->ee != MHI_EE_AMSS)
+               goto pci_suspend; /* Nothing to do at MHI level */
+
        /* Transition to M3 state */
-       mhi_pm_suspend(mhi_cntrl);
+       err = mhi_pm_suspend(mhi_cntrl);
+       if (err) {
+               dev_err(&pdev->dev, "failed to suspend device: %d\n", err);
+               clear_bit(MHI_PCI_DEV_SUSPENDED, &mhi_pdev->status);
+               return -EBUSY;
+       }
 
+pci_suspend:
        pci_disable_device(pdev);
        pci_wake_from_d3(pdev, true);
 
        return 0;
 }
 
-static int __maybe_unused mhi_pci_resume(struct device *dev)
+static int __maybe_unused mhi_pci_runtime_resume(struct device *dev)
 {
        struct pci_dev *pdev = to_pci_dev(dev);
        struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
        struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
        int err;
 
+       if (!test_and_clear_bit(MHI_PCI_DEV_SUSPENDED, &mhi_pdev->status))
+               return 0;
+
        err = pci_enable_device(pdev);
        if (err)
                goto err_recovery;
@@ -741,6 +786,10 @@ static int __maybe_unused mhi_pci_resume(struct device *dev)
        pci_set_master(pdev);
        pci_wake_from_d3(pdev, false);
 
+       if (!test_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status) ||
+                       mhi_cntrl->ee != MHI_EE_AMSS)
+               return 0; /* Nothing to do at MHI level */
+
        /* Exit M3, transition to M0 state */
        err = mhi_pm_resume(mhi_cntrl);
        if (err) {
@@ -751,16 +800,44 @@ static int __maybe_unused mhi_pci_resume(struct device *dev)
        /* Resume health check */
        mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);
 
+       /* It can be a remote wakeup (no mhi runtime_get), update access time */
+       pm_runtime_mark_last_busy(dev);
+
        return 0;
 
 err_recovery:
-       /* The device may have loose power or crashed, try recovering it */
+       /* Do not fail to not mess up our PCI device state, the device likely
+        * lost power (d3cold) and we simply need to reset it from the recovery
+        * procedure, trigger the recovery asynchronously to prevent system
+        * suspend exit delaying.
+        */
        queue_work(system_long_wq, &mhi_pdev->recovery_work);
+       pm_runtime_mark_last_busy(dev);
 
-       return err;
+       return 0;
+}
+
+static int  __maybe_unused mhi_pci_suspend(struct device *dev)
+{
+       pm_runtime_disable(dev);
+       return mhi_pci_runtime_suspend(dev);
+}
+
+static int __maybe_unused mhi_pci_resume(struct device *dev)
+{
+       int ret;
+
+       /* Depending the platform, device may have lost power (d3cold), we need
+        * to resume it now to check its state and recover when necessary.
+        */
+       ret = mhi_pci_runtime_resume(dev);
+       pm_runtime_enable(dev);
+
+       return ret;
 }
 
 static const struct dev_pm_ops mhi_pci_pm_ops = {
+       SET_RUNTIME_PM_OPS(mhi_pci_runtime_suspend, mhi_pci_runtime_resume, NULL)
        SET_SYSTEM_SLEEP_PM_OPS(mhi_pci_suspend, mhi_pci_resume)
 };