drivers/pci/pcie/aspm.c

Source file repositories/reference/linux-study-clean/drivers/pci/pcie/aspm.c

File Facts

System
Linux kernel
Corpus path
drivers/pci/pcie/aspm.c
Extension
.c
Size
54018 bytes
Lines
1787
Domain
Representative Device Path
Bucket
PCIe NVMe Storage Path
Inferred role
Representative Device Path: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Part of the selected hardware vertical slice: PCI discovery, driver binding, NVMe queues, block requests, DMA, interrupts, and completion.

Dependency Surface

Detected Declarations

Annotated Snippet

struct pcie_link_state {
	struct pci_dev *pdev;		/* Upstream component of the Link */
	struct pci_dev *downstream;	/* Downstream component, function 0 */
	struct pcie_link_state *root;	/* pointer to the root port link */
	struct pcie_link_state *parent;	/* pointer to the parent Link state */
	struct list_head sibling;	/* node in link_list */

	/* ASPM state */
	u32 aspm_support:7;		/* Supported ASPM state */
	u32 aspm_enabled:7;		/* Enabled ASPM state */
	u32 aspm_capable:7;		/* Capable ASPM state with latency */
	u32 aspm_default:7;		/* Default ASPM state by BIOS or
					   override */
	u32 aspm_disable:7;		/* Disabled ASPM state */

	/* Clock PM state */
	u32 clkpm_capable:1;		/* Clock PM capable? */
	u32 clkpm_enabled:1;		/* Current Clock PM state */
	u32 clkpm_default:1;		/* Default Clock PM state by BIOS */
	u32 clkpm_disable:1;		/* Clock PM disabled */
};

static bool aspm_disabled, aspm_force;
static bool aspm_support_enabled = true;
static DEFINE_MUTEX(aspm_lock);
static LIST_HEAD(link_list);

#define POLICY_DEFAULT 0	/* BIOS default setting */
#define POLICY_PERFORMANCE 1	/* high performance */
#define POLICY_POWERSAVE 2	/* high power saving */
#define POLICY_POWER_SUPERSAVE 3 /* possibly even more power saving */

#ifdef CONFIG_PCIEASPM_PERFORMANCE
static int aspm_policy = POLICY_PERFORMANCE;
#elif defined CONFIG_PCIEASPM_POWERSAVE
static int aspm_policy = POLICY_POWERSAVE;
#elif defined CONFIG_PCIEASPM_POWER_SUPERSAVE
static int aspm_policy = POLICY_POWER_SUPERSAVE;
#else
static int aspm_policy;
#endif

static const char *policy_str[] = {
	[POLICY_DEFAULT] = "default",
	[POLICY_PERFORMANCE] = "performance",
	[POLICY_POWERSAVE] = "powersave",
	[POLICY_POWER_SUPERSAVE] = "powersupersave"
};

/*
 * The L1 PM substate capability is only implemented in function 0 in a
 * multi function device.
 */
static struct pci_dev *pci_function_0(struct pci_bus *linkbus)
{
	struct pci_dev *child;

	list_for_each_entry(child, &linkbus->devices, bus_list)
		if (PCI_FUNC(child->devfn) == 0)
			return child;
	return NULL;
}

static int policy_to_aspm_state(struct pcie_link_state *link)
{
	switch (aspm_policy) {
	case POLICY_PERFORMANCE:
		/* Disable ASPM and Clock PM */
		return 0;
	case POLICY_POWERSAVE:
		/* Enable ASPM L0s/L1 */
		return PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1;
	case POLICY_POWER_SUPERSAVE:
		/* Enable Everything */
		return PCIE_LINK_STATE_ASPM_ALL;
	case POLICY_DEFAULT:
		return link->aspm_default;
	}
	return 0;
}

static int policy_to_clkpm_state(struct pcie_link_state *link)
{
	switch (aspm_policy) {
	case POLICY_PERFORMANCE:
		/* Disable ASPM and Clock PM */
		return 0;
	case POLICY_POWERSAVE:
	case POLICY_POWER_SUPERSAVE:
		/* Enable Clock PM */

Annotation

Implementation Notes