PCI/ASPM: Add pci_enable_link_state()

Add pci_enable_link_state() to allow devices to change the default BIOS
configured states. Clears the BIOS default settings then sets the new
states and reconfigures the link under the semaphore. Also add
PCIE_LINK_STATE_ALL macro for convenience for callers that want to enable
all link states.

Link: https://lore.kernel.org/r/20230120031522.2304439-2-david.e.box@linux.intel.com
Signed-off-by: Michael Bottini <michael.a.bottini@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 53a1fa306e1ee7b70f20581dbca928792dbe6384..339c686a5094c0e611193e69d2a1f7cf545d204a 100644 (file)
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1181,6 +1181,60 @@ int pci_disable_link_state(struct pci_dev *pdev, int state)
 }
 EXPORT_SYMBOL(pci_disable_link_state);
 
+/**
+ * pci_enable_link_state - Clear and set the default device link state so that
+ * the link may be allowed to enter the specified states. Note that if the
+ * BIOS didn't grant ASPM control to the OS, this does nothing because we can't
+ * touch the LNKCTL register. Also note that this does not enable states
+ * disabled by pci_disable_link_state(). Return 0 or a negative errno.
+ *
+ * @pdev: PCI device
+ * @state: Mask of ASPM link states to enable
+ */
+int pci_enable_link_state(struct pci_dev *pdev, int state)
+{
+       struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+
+       if (!link)
+               return -EINVAL;
+       /*
+        * A driver requested that ASPM be enabled on this device, but
+        * if we don't have permission to manage ASPM (e.g., on ACPI
+        * systems we have to observe the FADT ACPI_FADT_NO_ASPM bit and
+        * the _OSC method), we can't honor that request.
+        */
+       if (aspm_disabled) {
+               pci_warn(pdev, "can't override BIOS ASPM; OS doesn't have ASPM control\n");
+               return -EPERM;
+       }
+
+       down_read(&pci_bus_sem);
+       mutex_lock(&aspm_lock);
+       link->aspm_default = 0;
+       if (state & PCIE_LINK_STATE_L0S)
+               link->aspm_default |= ASPM_STATE_L0S;
+       if (state & PCIE_LINK_STATE_L1)
+               /* L1 PM substates require L1 */
+               link->aspm_default |= ASPM_STATE_L1 | ASPM_STATE_L1SS;
+       if (state & PCIE_LINK_STATE_L1_1)
+               link->aspm_default |= ASPM_STATE_L1_1;
+       if (state & PCIE_LINK_STATE_L1_2)
+               link->aspm_default |= ASPM_STATE_L1_2;
+       if (state & PCIE_LINK_STATE_L1_1_PCIPM)
+               link->aspm_default |= ASPM_STATE_L1_1_PCIPM;
+       if (state & PCIE_LINK_STATE_L1_2_PCIPM)
+               link->aspm_default |= ASPM_STATE_L1_2_PCIPM;
+       pcie_config_aspm_link(link, policy_to_aspm_state(link));
+
+       link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0;
+       pcie_set_clkpm(link, policy_to_clkpm_state(link));
+       mutex_unlock(&aspm_lock);
+       up_read(&pci_bus_sem);
+
+       return 0;
+}
+EXPORT_SYMBOL(pci_enable_link_state);
+
 static int pcie_aspm_set_policy(const char *val,
                                const struct kernel_param *kp)
 {

diff --git a/include/linux/pci.h b/include/linux/pci.h
index adffd65e84b4e28cade5df01b412d7ac9251c25a..ea601e6fbbda205721344d6eb5891810e70c07b6 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1685,10 +1685,15 @@ extern bool pcie_ports_native;
 #define PCIE_LINK_STATE_L1_2           BIT(4)
 #define PCIE_LINK_STATE_L1_1_PCIPM     BIT(5)
 #define PCIE_LINK_STATE_L1_2_PCIPM     BIT(6)
+#define PCIE_LINK_STATE_ALL            (PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1 |\
+                                        PCIE_LINK_STATE_CLKPM | PCIE_LINK_STATE_L1_1 |\
+                                        PCIE_LINK_STATE_L1_2 | PCIE_LINK_STATE_L1_1_PCIPM |\
+                                        PCIE_LINK_STATE_L1_2_PCIPM)
 
 #ifdef CONFIG_PCIEASPM
 int pci_disable_link_state(struct pci_dev *pdev, int state);
 int pci_disable_link_state_locked(struct pci_dev *pdev, int state);
+int pci_enable_link_state(struct pci_dev *pdev, int state);
 void pcie_no_aspm(void);
 bool pcie_aspm_support_enabled(void);
 bool pcie_aspm_enabled(struct pci_dev *pdev);
@@ -1697,6 +1702,8 @@ static inline int pci_disable_link_state(struct pci_dev *pdev, int state)
 { return 0; }
 static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state)
 { return 0; }
+static inline int pci_enable_link_state(struct pci_dev *pdev, int state)
+{ return 0; }
 static inline void pcie_no_aspm(void) { }
 static inline bool pcie_aspm_support_enabled(void) { return false; }
 static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }