The _RST is a standard method specified in the ACPI specification. It provides a function level reset when it is described in the acpi_device context associated with PCI-device. Implement a new reset function pci_dev_acpi_reset() for probing RST method and execute if it is defined in the firmware. The ACPI binding information is available only after calling device_add(), so move pci_init_reset_methods() to end of the pci_device_add(). The default priority of the acpi reset is set to below device-specific and above hardware resets. Signed-off-by: Shanker Donthineni <sdonthineni@xxxxxxxxxx> --- changes since v2: - fix typo in the commit text changes since v2: - rebase patch on top of https://lore.kernel.org/linux-pci/20210409192324.30080-1-ameynarkhede03@xxxxxxxxx/ drivers/pci/pci.c | 30 ++++++++++++++++++++++++++++++ drivers/pci/probe.c | 2 +- include/linux/pci.h | 2 +- 3 files changed, 32 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 664cf2d358d6..510f9224a3b0 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5076,6 +5076,35 @@ static void pci_dev_restore(struct pci_dev *dev) err_handler->reset_done(dev); } +/** + * pci_dev_acpi_reset - do a function level reset using _RST method + * @dev: device to reset + * @probe: check if _RST method is included in the acpi_device context. + */ +static int pci_dev_acpi_reset(struct pci_dev *dev, int probe) +{ +#ifdef CONFIG_ACPI + acpi_handle handle = ACPI_HANDLE(&dev->dev); + + /* Return -ENOTTY if _RST method is not included in the dev context */ + if (!handle || !acpi_has_method(handle, "_RST")) + return -ENOTTY; + + /* Return 0 for probe phase indicating that we can reset this device */ + if (probe) + return 0; + + /* Invoke _RST() method to perform a function level reset */ + if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL, NULL))) { + pci_warn(dev, "Failed to reset the device\n"); + return -EINVAL; + } + return 0; +#else + return -ENOTTY; +#endif +} + /* * The ordering for functions in pci_reset_fn_methods * is required for reset_methods byte array defined @@ -5083,6 +5112,7 @@ static void pci_dev_restore(struct pci_dev *dev) */ const struct pci_reset_fn_method pci_reset_fn_methods[] = { { .reset_fn = &pci_dev_specific_reset, .name = "device_specific" }, + { .reset_fn = &pci_dev_acpi_reset, .name = "acpi_reset" }, { .reset_fn = &pcie_reset_flr, .name = "flr" }, { .reset_fn = &pci_af_flr, .name = "af_flr" }, { .reset_fn = &pci_pm_reset, .name = "pm" }, diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 4764e031a44b..d4becd6ffb52 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2403,7 +2403,6 @@ static void pci_init_capabilities(struct pci_dev *dev) pci_rcec_init(dev); /* Root Complex Event Collector */ pcie_report_downtraining(dev); - pci_init_reset_methods(dev); } /* @@ -2494,6 +2493,7 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) dev->match_driver = false; ret = device_add(&dev->dev); WARN_ON(ret < 0); + pci_init_reset_methods(dev); } struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn) diff --git a/include/linux/pci.h b/include/linux/pci.h index 9f8347799634..b4a5d2146542 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -49,7 +49,7 @@ PCI_STATUS_SIG_TARGET_ABORT | \ PCI_STATUS_PARITY) -#define PCI_RESET_FN_METHODS 5 +#define PCI_RESET_FN_METHODS 6 /* * The PCI interface treats multi-function devices as independent -- 2.17.1
