From: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
Implement _DSM Method 0Bh as per PCI firmware specs
section 4.6.11 Rev 3.3.
Signed-off-by: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
Signed-off-by: Badal Nilawar <badal.nilawar@xxxxxxxxx>
---
drivers/pci/pci-acpi.c | 57 ++++++++++++++++++++++++++++++++++++++++
include/linux/pci-acpi.h | 8 +++++-
2 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index d33efba4ca94..88044491feaa 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -1531,6 +1531,63 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power,
}
EXPORT_SYMBOL_GPL(pci_acpi_request_d3cold_aux_power);
+/**
+ * pci_acpi_add_perst_assertion_delay - Request PERST# delay via ACPI DSM
+ * @dev: PCI device instance
+ * @delay_us: Requested delay_us
+ *
+ * This function sends a request to the host BIOS via ACPI _DSM to grant the
+ * required PERST# delay for the specified PCI device. It evaluates the _DSM
+ * to request the PERST# delay and handles the response accordingly.
+ *
+ * Return: returns 0 on success and errno on failure.
+ */
+int pci_acpi_add_perst_assertion_delay(struct pci_dev *dev, u32 delay_us)
+{
+ union acpi_object in_obj = {
+ .integer.type = ACPI_TYPE_INTEGER,
+ .integer.value = delay_us,
+ };
+
+ union acpi_object *out_obj;
+ acpi_handle handle;
+ int result, ret = -EINVAL;
+
+ if (!dev)
+ return -EINVAL;
+
+ handle = ACPI_HANDLE(&dev->dev);
+ if (!handle)
+ return -EINVAL;
+
+ if (!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 4, 1 << DSM_PCI_PERST_ASSERTION_DELAY)) {
+ pci_dbg(dev, "ACPI _DSM 0%Xh not supported\n", DSM_PCI_PERST_ASSERTION_DELAY);
+ return -ENODEV;
+ }
+
+ out_obj = acpi_evaluate_dsm_typed(handle, &pci_acpi_dsm_guid, 4,
+ DSM_PCI_PERST_ASSERTION_DELAY,
+ &in_obj, ACPI_TYPE_INTEGER);
+ if (!out_obj)
+ return -EINVAL;
+
+ result = out_obj->integer.value;
+
+ if (result == delay_us) {
+ pci_info(dev, "PERST# Assertion Delay set to %u microseconds\n", delay_us);
+ ret = 0;
+ } else if (result == 0) {
+ pci_warn(dev, "PERST# Assertion Delay request failed, no previous valid request\n");
+ } else {
+ pci_warn(dev, "PERST# Assertion Delay request failed, Previous valid delay: %u microseconds\n",
+ result);
+ }
+
+ ACPI_FREE(out_obj);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(pci_acpi_add_perst_assertion_delay);
+
static void pci_acpi_set_external_facing(struct pci_dev *dev)
{
u8 val;
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index 6079306ad754..e53d4893cf56 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -122,6 +122,7 @@ extern const guid_t pci_acpi_dsm_guid;
#define DSM_PCI_POWER_ON_RESET_DELAY 0x08
#define DSM_PCI_DEVICE_READINESS_DURATIONS 0x09
#define DSM_PCI_D3COLD_AUX_POWER_LIMIT 0x0A
+#define DSM_PCI_PERST_ASSERTION_DELAY 0x0B
#ifdef CONFIG_PCIE_EDR
void pci_acpi_add_edr_notifier(struct pci_dev *pdev);
@@ -135,7 +136,7 @@ int pci_acpi_set_companion_lookup_hook(struct acpi_device *(*func)(struct pci_de
void pci_acpi_clear_companion_lookup_hook(void);
int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power,
u32 *retry_interval);
-
+int pci_acpi_add_perst_assertion_delay(struct pci_dev *dev, u32 delay_us);
#else /* CONFIG_ACPI */
static inline void acpi_pci_add_bus(struct pci_bus *bus) { }
static inline void acpi_pci_remove_bus(struct pci_bus *bus) { }
@@ -144,6 +145,11 @@ static inline int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 req
{
return -EOPNOTSUPP;
}
+
+static inline int pci_acpi_add_perst_assertion_delay(struct pci_dev *dev, u32 delay_us)
+{
+ return -EOPNOTSUPP;
+}
#endif /* CONFIG_ACPI */
#endif /* _PCI_ACPI_H_ */
--
2.34.1
