Commit de82f60f authored by Michael Bottini's avatar Michael Bottini Committed by Lorenzo Pieralisi
Browse files

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: default avatarMichael Bottini <michael.a.bottini@linux.intel.com>
Signed-off-by: default avatarDavid E. Box <david.e.box@linux.intel.com>
Signed-off-by: default avatarLorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 1b929c02

drivers/pci/pcie/aspm.c

+54 −0
Original line number Diff line number Diff line
@@ -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)

{

include/linux/pci.h

+7 −0
Original line number Diff line number Diff line
@@ -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; }