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Subject[PATCH v8 7/8] PCI: Add support for ACPI _RST reset method
Date
From: Shanker Donthineni <sdonthineni@nvidia.com>

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 default priority of the ACPI reset is set to below device-specific
and above hardware resets.

Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
---
drivers/pci/pci-acpi.c | 23 +++++++++++++++++++++++
drivers/pci/pci.c | 1 +
drivers/pci/pci.h | 6 ++++++
include/linux/pci.h | 2 +-
4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index dae021322..b6de71d15 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -941,6 +941,29 @@ void pci_set_acpi_fwnode(struct pci_dev *dev)
acpi_pci_find_companion(&dev->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.
+ */
+int pci_dev_acpi_reset(struct pci_dev *dev, int probe)
+{
+ acpi_handle handle = ACPI_HANDLE(&dev->dev);
+
+ if (!handle || !acpi_has_method(handle, "_RST"))
+ return -ENOTTY;
+
+ if (probe)
+ return 0;
+
+ if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL, NULL))) {
+ pci_warn(dev, "ACPI _RST failed\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static bool acpi_pci_bridge_d3(struct pci_dev *dev)
{
const struct fwnode_handle *fwnode;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index db4e035cf..ec9fec952 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5116,6 +5116,7 @@ static void pci_dev_restore(struct pci_dev *dev)
const struct pci_reset_fn_method pci_reset_fn_methods[] = {
{ },
{ &pci_dev_specific_reset, .name = "device_specific" },
+ { &pci_dev_acpi_reset, .name = "acpi" },
{ &pcie_reset_flr, .name = "flr" },
{ &pci_af_flr, .name = "af_flr" },
{ &pci_pm_reset, .name = "pm" },
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 990b73e90..2c12017ed 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -705,7 +705,13 @@ static inline int pci_aer_raw_clear_status(struct pci_dev *dev) { return -EINVAL
int pci_acpi_program_hp_params(struct pci_dev *dev);
extern const struct attribute_group pci_dev_acpi_attr_group;
void pci_set_acpi_fwnode(struct pci_dev *dev);
+int pci_dev_acpi_reset(struct pci_dev *dev, int probe);
#else
+static inline int pci_dev_acpi_reset(struct pci_dev *dev, int probe)
+{
+ return -ENOTTY;
+}
+
static inline void pci_set_acpi_fwnode(struct pci_dev *dev) {}
static inline int pci_acpi_program_hp_params(struct pci_dev *dev)
{
diff --git a/include/linux/pci.h b/include/linux/pci.h
index a295e621f..d091b2948 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -50,7 +50,7 @@
PCI_STATUS_PARITY)

/* Number of reset methods used in pci_reset_fn_methods array in pci.c */
-#define PCI_NUM_RESET_METHODS 6
+#define PCI_NUM_RESET_METHODS 7

/*
* The PCI interface treats multi-function devices as independent
--
2.32.0
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