mhi: pci_generic: Add support for reset

Add support for resetting the device, reset can be triggered in case
of error or manually via sysfs (/sys/bus/pci/devices/*/reset).

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@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 778d13f..f0dfa62 100644 (file)
--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -8,6 +8,7 @@
  * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
  */
 
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/mhi.h>
 #include <linux/module.h>
@@ -15,6 +16,7 @@
 
 #define MHI_PCI_DEFAULT_BAR_NUM 0
 
+#define MHI_POST_RESET_DELAY_MS 500
 /**
  * struct mhi_pci_dev_info - MHI PCI device specific information
  * @config: MHI controller configuration
@@ -177,6 +179,16 @@ static const struct pci_device_id mhi_pci_id_table[] = {
 };
 MODULE_DEVICE_TABLE(pci, mhi_pci_id_table);
 
+enum mhi_pci_device_status {
+       MHI_PCI_DEV_STARTED,
+};
+
+struct mhi_pci_device {
+       struct mhi_controller mhi_cntrl;
+       struct pci_saved_state *pci_state;
+       unsigned long status;
+};
+
 static int mhi_pci_read_reg(struct mhi_controller *mhi_cntrl,
                            void __iomem *addr, u32 *out)
 {
@@ -196,6 +208,20 @@ static void mhi_pci_status_cb(struct mhi_controller *mhi_cntrl,
        /* Nothing to do for now */
 }
 
+static bool mhi_pci_is_alive(struct mhi_controller *mhi_cntrl)
+{
+       struct pci_dev *pdev = to_pci_dev(mhi_cntrl->cntrl_dev);
+       u16 vendor = 0;
+
+       if (pci_read_config_word(pdev, PCI_VENDOR_ID, &vendor))
+               return false;
+
+       if (vendor == (u16) ~0 || vendor == 0)
+               return false;
+
+       return true;
+}
+
 static int mhi_pci_claim(struct mhi_controller *mhi_cntrl,
                         unsigned int bar_num, u64 dma_mask)
 {
@@ -291,16 +317,20 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
        const struct mhi_pci_dev_info *info = (struct mhi_pci_dev_info *) id->driver_data;
        const struct mhi_controller_config *mhi_cntrl_config;
+       struct mhi_pci_device *mhi_pdev;
        struct mhi_controller *mhi_cntrl;
        int err;
 
        dev_dbg(&pdev->dev, "MHI PCI device found: %s\n", info->name);
 
-       mhi_cntrl = mhi_alloc_controller();
-       if (!mhi_cntrl)
+       /* mhi_pdev.mhi_cntrl must be zero-initialized */
+       mhi_pdev = devm_kzalloc(&pdev->dev, sizeof(*mhi_pdev), GFP_KERNEL);
+       if (!mhi_pdev)
                return -ENOMEM;
 
        mhi_cntrl_config = info->config;
+       mhi_cntrl = &mhi_pdev->mhi_cntrl;
+
        mhi_cntrl->cntrl_dev = &pdev->dev;
        mhi_cntrl->iova_start = 0;
        mhi_cntrl->iova_stop = (dma_addr_t)DMA_BIT_MASK(info->dma_data_width);
@@ -315,17 +345,21 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
        err = mhi_pci_claim(mhi_cntrl, info->bar_num, DMA_BIT_MASK(info->dma_data_width));
        if (err)
-               goto err_release;
+               return err;
 
        err = mhi_pci_get_irqs(mhi_cntrl, mhi_cntrl_config);
        if (err)
-               goto err_release;
+               return err;
+
+       pci_set_drvdata(pdev, mhi_pdev);
 
-       pci_set_drvdata(pdev, mhi_cntrl);
+       /* Have stored pci confspace at hand for restore in sudden PCI error */
+       pci_save_state(pdev);
+       mhi_pdev->pci_state = pci_store_saved_state(pdev);
 
        err = mhi_register_controller(mhi_cntrl, mhi_cntrl_config);
        if (err)
-               goto err_release;
+               return err;
 
        /* MHI bus does not power up the controller by default */
        err = mhi_prepare_for_power_up(mhi_cntrl);
@@ -340,33 +374,94 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
                goto err_unprepare;
        }
 
+       set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);
+
        return 0;
 
 err_unprepare:
        mhi_unprepare_after_power_down(mhi_cntrl);
 err_unregister:
        mhi_unregister_controller(mhi_cntrl);
-err_release:
-       mhi_free_controller(mhi_cntrl);
 
        return err;
 }
 
 static void mhi_pci_remove(struct pci_dev *pdev)
 {
-       struct mhi_controller *mhi_cntrl = pci_get_drvdata(pdev);
+       struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
+       struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
+
+       if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
+               mhi_power_down(mhi_cntrl, true);
+               mhi_unprepare_after_power_down(mhi_cntrl);
+       }
 
-       mhi_power_down(mhi_cntrl, true);
-       mhi_unprepare_after_power_down(mhi_cntrl);
        mhi_unregister_controller(mhi_cntrl);
-       mhi_free_controller(mhi_cntrl);
 }
 
+static void mhi_pci_reset_prepare(struct pci_dev *pdev)
+{
+       struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
+       struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
+
+       dev_info(&pdev->dev, "reset\n");
+
+       /* Clean up MHI state */
+       if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
+               mhi_power_down(mhi_cntrl, false);
+               mhi_unprepare_after_power_down(mhi_cntrl);
+       }
+
+       /* cause internal device reset */
+       mhi_soc_reset(mhi_cntrl);
+
+       /* Be sure device reset has been executed */
+       msleep(MHI_POST_RESET_DELAY_MS);
+}
+
+static void mhi_pci_reset_done(struct pci_dev *pdev)
+{
+       struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
+       struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
+       int err;
+
+       /* Restore initial known working PCI state */
+       pci_load_saved_state(pdev, mhi_pdev->pci_state);
+       pci_restore_state(pdev);
+
+       /* Is device status available ? */
+       if (!mhi_pci_is_alive(mhi_cntrl)) {
+               dev_err(&pdev->dev, "reset failed\n");
+               return;
+       }
+
+       err = mhi_prepare_for_power_up(mhi_cntrl);
+       if (err) {
+               dev_err(&pdev->dev, "failed to prepare MHI controller\n");
+               return;
+       }
+
+       err = mhi_sync_power_up(mhi_cntrl);
+       if (err) {
+               dev_err(&pdev->dev, "failed to power up MHI controller\n");
+               mhi_unprepare_after_power_down(mhi_cntrl);
+               return;
+       }
+
+       set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);
+}
+
+static const struct pci_error_handlers mhi_pci_err_handler = {
+       .reset_prepare = mhi_pci_reset_prepare,
+       .reset_done = mhi_pci_reset_done,
+};
+
 static struct pci_driver mhi_pci_driver = {
        .name           = "mhi-pci-generic",
        .id_table       = mhi_pci_id_table,
        .probe          = mhi_pci_probe,
-       .remove         = mhi_pci_remove
+       .remove         = mhi_pci_remove,
+       .err_handler    = &mhi_pci_err_handler,
 };
 module_pci_driver(mhi_pci_driver);