path: root/drivers/pci/pcie/aspm.c

/*
 * File:	drivers/pci/pcie/aspm.c
 * Enabling PCIe link L0s/L1 state and Clock Power Management
 *
 * Copyright (C) 2007 Intel
 * Copyright (C) Zhang Yanmin (yanmin.zhang@intel.com)
 * Copyright (C) Shaohua Li (shaohua.li@intel.com)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>
#include <linux/errno.h>
#include <linux/pm.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/delay.h>
#include <linux/pci-aspm.h>
#include "../pci.h"

#ifdef MODULE_PARAM_PREFIX
#undef MODULE_PARAM_PREFIX
#endif
#define MODULE_PARAM_PREFIX "pcie_aspm."

/* Note: those are not register definitions */
#define ASPM_STATE_L0S_UP	(1)	/* Upstream direction L0s state */
#define ASPM_STATE_L0S_DW	(2)	/* Downstream direction L0s state */
#define ASPM_STATE_L1		(4)	/* L1 state */
#define ASPM_STATE_L0S		(ASPM_STATE_L0S_UP | ASPM_STATE_L0S_DW)
#define ASPM_STATE_ALL		(ASPM_STATE_L0S | ASPM_STATE_L1)

struct aspm_latency {
	u32 l0s;			/* L0s latency (nsec) */
	u32 l1;				/* L1 latency (nsec) */
};

struct pcie_link_state {
	struct pci_dev *pdev;		/* Upstream component of the Link */
	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 */
	struct list_head children;	/* list of child link states */
	struct list_head link;		/* node in parent's children list */

	/* ASPM state */
	u32 aspm_support:3;		/* Supported ASPM state */
	u32 aspm_enabled:3;		/* Enabled ASPM state */
	u32 aspm_capable:3;		/* Capable ASPM state with latency */
	u32 aspm_default:3;		/* Default ASPM state by BIOS */
	u32 aspm_disable:3;		/* 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 */

	/* Exit latencies */
	struct aspm_latency latency_up;	/* Upstream direction exit latency */
	struct aspm_latency latency_dw;	/* Downstream direction exit latency */
	/*
	 * Endpoint acceptable latencies. A pcie downstream port only
	 * has one slot under it, so at most there are 8 functions.
	 */
	struct aspm_latency acceptable[8];
};

static int 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 */

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

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

#define LINK_RETRAIN_TIMEOUT HZ

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 ASPM_STATE_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:
		/* Disable Clock PM */
		return 1;
	case POLICY_DEFAULT:
		return link->clkpm_default;
	}
	return 0;
}

static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
{
	struct pci_dev *child;
	struct pci_bus *linkbus = link->pdev->subordinate;

	list_for_each_entry(child, &linkbus->devices, bus_list) {
		if (enable)
			pcie_capability_set_word(child, PCI_EXP_LNKCTL,
						 PCI_EXP_LNKCTL_CLKREQ_EN);
		else
			pcie_capability_clear_word(child, PCI_EXP_LNKCTL,
						   PCI_EXP_LNKCTL_CLKREQ_EN);
	}
	link->clkpm_enabled = !!enable;
}

static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
{
	/* Don't enable Clock PM if the link is not Clock PM capable */
	if (!link->clkpm_capable && enable)
		enable = 0;
	/* Need nothing if the specified equals to current state */
	if (link->clkpm_enabled == enable)
		return;
	pcie_set_clkpm_nocheck(link, enable);
}

static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
{
	int capable = 1, enabled = 1;
	u32 reg32;
	u16 reg16;
	struct pci_dev *child;
	struct pci_bus *linkbus = link->pdev->subordinate;

	/* All functions should have the same cap and state, take the worst */
	list_for_each_entry(child, &linkbus->devices, bus_list) {
		pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &reg32);
		if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
			capable = 0;
			enabled = 0;
			break;
		}
		pcie_capabilit