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mhi: pci_generic: Add health-check
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If the modem crashes for any reason, we may not be able to detect
it at MHI level (MHI registers not reachable anymore).

This patch implements a health-check mechanism to check regularly
that device is alive (MHI layer can communicate with). If device
is not alive (because a crash or unexpected reset), the recovery
procedure is triggered.

Tested successfully with Telit FN980m module.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
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Loic Poulain authored and Manivannan Sadhasivam committed Jan 4, 2021
1 parent b012ee6 commit 8562d4f
Showing 1 changed file with 35 additions and 0 deletions.
35 changes: 35 additions & 0 deletions drivers/bus/mhi/pci_generic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,11 +14,15 @@
#include <linux/mhi.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/timer.h>
#include <linux/workqueue.h>

#define MHI_PCI_DEFAULT_BAR_NUM 0

#define MHI_POST_RESET_DELAY_MS 500

#define HEALTH_CHECK_PERIOD (HZ * 2)

/**
* struct mhi_pci_dev_info - MHI PCI device specific information
* @config: MHI controller configuration
Expand Down Expand Up @@ -189,6 +193,7 @@ struct mhi_pci_device {
struct mhi_controller mhi_cntrl;
struct pci_saved_state *pci_state;
struct work_struct recovery_work;
struct timer_list health_check_timer;
unsigned long status;
};

Expand Down Expand Up @@ -326,6 +331,8 @@ 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);

/* Clean up MHI state */
if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
mhi_power_down(mhi_cntrl, false);
Expand All @@ -351,6 +358,7 @@ static void mhi_pci_recovery_work(struct work_struct *work)
dev_dbg(&pdev->dev, "Recovery completed\n");

set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);
mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);
return;

err_unprepare:
Expand All @@ -360,6 +368,21 @@ static void mhi_pci_recovery_work(struct work_struct *work)
dev_err(&pdev->dev, "Recovery failed\n");
}

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 (!mhi_pci_is_alive(mhi_cntrl)) {
dev_err(mhi_cntrl->cntrl_dev, "Device died\n");
queue_work(system_long_wq, &mhi_pdev->recovery_work);
return;
}

/* reschedule in two seconds */
mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);
}

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;
Expand All @@ -376,6 +399,7 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
return -ENOMEM;

INIT_WORK(&mhi_pdev->recovery_work, mhi_pci_recovery_work);
timer_setup(&mhi_pdev->health_check_timer, health_check, 0);

mhi_cntrl_config = info->config;
mhi_cntrl = &mhi_pdev->mhi_cntrl;
Expand Down Expand Up @@ -427,6 +451,9 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)

set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);

/* start health check */
mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);

return 0;

err_unprepare:
Expand All @@ -442,6 +469,7 @@ static void mhi_pci_remove(struct pci_dev *pdev)
struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;

del_timer(&mhi_pdev->health_check_timer);
cancel_work_sync(&mhi_pdev->recovery_work);

if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
Expand All @@ -459,6 +487,8 @@ static void mhi_pci_reset_prepare(struct pci_dev *pdev)

dev_info(&pdev->dev, "reset\n");

del_timer(&mhi_pdev->health_check_timer);

/* Clean up MHI state */
if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
mhi_power_down(mhi_cntrl, false);
Expand Down Expand Up @@ -502,6 +532,7 @@ static void mhi_pci_reset_done(struct pci_dev *pdev)
}

set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);
mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);
}

static pci_ers_result_t mhi_pci_error_detected(struct pci_dev *pdev,
Expand Down Expand Up @@ -562,6 +593,7 @@ static int __maybe_unused mhi_pci_suspend(struct device *dev)
struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;

del_timer(&mhi_pdev->health_check_timer);
cancel_work_sync(&mhi_pdev->recovery_work);

/* Transition to M3 state */
Expand Down Expand Up @@ -597,6 +629,9 @@ static int __maybe_unused mhi_pci_resume(struct device *dev)
goto err_recovery;
}

/* Resume health check */
mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);

return 0;

err_recovery:
Expand Down

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