Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1440 insertions, 0 deletions

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
new file mode 100644
index 0000000000..7e3b342215
--- /dev/null
+++ b/drivers/pci/pcie/aspm.c
@@ -0,0 +1,1440 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Enable 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/math.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 "../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_L1_1		(8)	/* ASPM L1.1 state */
+#define ASPM_STATE_L1_2		(0x10)	/* ASPM L1.2 state */
+#define ASPM_STATE_L1_1_PCIPM	(0x20)	/* PCI PM L1.1 state */
+#define ASPM_STATE_L1_2_PCIPM	(0x40)	/* PCI PM L1.2 state */
+#define ASPM_STATE_L1_SS_PCIPM	(ASPM_STATE_L1_1_PCIPM | ASPM_STATE_L1_2_PCIPM)
+#define ASPM_STATE_L1_2_MASK	(ASPM_STATE_L1_2 | ASPM_STATE_L1_2_PCIPM)
+#define ASPM_STATE_L1SS		(ASPM_STATE_L1_1 | ASPM_STATE_L1_1_PCIPM |\
+				 ASPM_STATE_L1_2_MASK)
+#define ASPM_STATE_L0S		(ASPM_STATE_L0S_UP | ASPM_STATE_L0S_DW)
+#define ASPM_STATE_ALL		(ASPM_STATE_L0S | ASPM_STATE_L1 |	\
+				 ASPM_STATE_L1SS)
+
+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 */
+	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 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 */
+#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 (ASPM_STATE_L0S | ASPM_STATE_L1);
+	case POLICY_POWER_SUPERSAVE:
+		/* Enable Everything */
+		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:
+	case POLICY_POWER_SUPERSAVE:
+		/* Enable 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;
+	u32 val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
+
+	list_for_each_entry(child, &linkbus->devices, bus_list)
+		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_CLKREQ_EN,
+						   val);
+	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
+	 * or Clock PM is disabled
+	 */
+	if (!link->clkpm_capable || link->clkpm_disable)
+		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_capability_read_word(child, PCI_EXP_LNKCTL, &reg16);
+		if (!(reg16 & PCI_EXP_LNKCTL_CLKREQ_EN))
+			enabled = 0;
+	}
+	link->clkpm_enabled = enabled;
+	link->clkpm_default = enabled;
+	link->clkpm_capable = capable;
+	link->clkpm_disable = blacklist ? 1 : 0;
+}
+
+/*
+ * pcie_aspm_configure_common_clock: check if the 2 ends of a link
+ *   could use common clock. If they are, configure them to use the
+ *   common clock. That will reduce the ASPM state exit latency.
+ */
+static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
+{
+	int same_clock = 1;
+	u16 reg16, ccc, parent_old_ccc, child_old_ccc[8];
+	struct pci_dev *child, *parent = link->pdev;
+	struct pci_bus *linkbus = parent->subordinate;
+	/*
+	 * All functions of a slot should have the same Slot Clock
+	 * Configuration, so just check one function
+	 */
+	child = list_entry(linkbus->devices.next, struct pci_dev, bus_list);
+	BUG_ON(!pci_is_pcie(child));
+
+	/* Check downstream component if bit Slot Clock Configuration is 1 */
+	pcie_capability_read_word(child, PCI_EXP_LNKSTA, &reg16);
+	if (!(reg16 & PCI_EXP_LNKSTA_SLC))
+		same_clock = 0;
+
+	/* Check upstream component if bit Slot Clock Configuration is 1 */
+	pcie_capability_read_word(parent, PCI_EXP_LNKSTA, &reg16);
+	if (!(reg16 & PCI_EXP_LNKSTA_SLC))
+		same_clock = 0;
+
+	/* Port might be already in common clock mode */
+	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
+	parent_old_ccc = reg16 & PCI_EXP_LNKCTL_CCC;
+	if (same_clock && (reg16 & PCI_EXP_LNKCTL_CCC)) {
+		bool consistent = true;
+
+		list_for_each_entry(child, &linkbus->devices, bus_list) {
+			pcie_capability_read_word(child, PCI_EXP_LNKCTL,
+						  &reg16);
+			if (!(reg16 & PCI_EXP_LNKCTL_CCC)) {
+				consistent = false;
+				break;
+			}
+		}
+		if (consistent)
+			return;
+		pci_info(parent, "ASPM: current common clock configuration is inconsistent, reconfiguring\n");
+	}
+
+	ccc = same_clock ? PCI_EXP_LNKCTL_CCC : 0;
+	/* Configure downstream component, all functions */
+	list_for_each_entry(child, &linkbus->devices, bus_list) {
+		pcie_capability_read_word(child, PCI_EXP_LNKCTL, &reg16);
+		child_old_ccc[PCI_FUNC(child->devfn)] = reg16 & PCI_EXP_LNKCTL_CCC;
+		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_CCC, ccc);
+	}
+
+	/* Configure upstream component */
+	pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
+					   PCI_EXP_LNKCTL_CCC, ccc);
+
+	if (pcie_retrain_link(link->pdev, true)) {
+
+		/* Training failed. Restore common clock configurations */
+		pci_err(parent, "ASPM: Could not configure common clock\n");
+		list_for_each_entry(child, &linkbus->devices, bus_list)
+			pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+							   PCI_EXP_LNKCTL_CCC,
+							   child_old_ccc[PCI_FUNC(child->devfn)]);
+		pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_CCC, parent_old_ccc);
+	}
+}
+
+/* Convert L0s latency encoding to ns */
+static u32 calc_l0s_latency(u32 lnkcap)
+{
+	u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L0SEL) >> 12;
+
+	if (encoding == 0x7)
+		return (5 * 1000);	/* > 4us */
+	return (64 << encoding);
+}
+
+/* Convert L0s acceptable latency encoding to ns */
+static u32 calc_l0s_acceptable(u32 encoding)
+{
+	if (encoding == 0x7)
+		return -1U;
+	return (64 << encoding);
+}
+
+/* Convert L1 latency encoding to ns */
+static u32 calc_l1_latency(u32 lnkcap)
+{
+	u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L1EL) >> 15;
+
+	if (encoding == 0x7)
+		return (65 * 1000);	/* > 64us */
+	return (1000 << encoding);
+}
+
+/* Convert L1 acceptable latency encoding to ns */
+static u32 calc_l1_acceptable(u32 encoding)
+{
+	if (encoding == 0x7)
+		return -1U;
+	return (1000 << encoding);
+}
+
+/* Convert L1SS T_pwr encoding to usec */
+static u32 calc_l12_pwron(struct pci_dev *pdev, u32 scale, u32 val)
+{
+	switch (scale) {
+	case 0:
+		return val * 2;
+	case 1:
+		return val * 10;
+	case 2:
+		return val * 100;
+	}
+	pci_err(pdev, "%s: Invalid T_PwrOn scale: %u\n", __func__, scale);
+	return 0;
+}
+
+/*
+ * Encode an LTR_L1.2_THRESHOLD value for the L1 PM Substates Control 1
+ * register.  Ports enter L1.2 when the most recent LTR value is greater
+ * than or equal to LTR_L1.2_THRESHOLD, so we round up to make sure we
+ * don't enter L1.2 too aggressively.
+ *
+ * See PCIe r6.0, sec 5.5.1, 6.18, 7.8.3.3.
+ */
+static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
+{
+	u64 threshold_ns = (u64) threshold_us * 1000;
+
+	/*
+	 * LTR_L1.2_THRESHOLD_Value ("value") is a 10-bit field with max
+	 * value of 0x3ff.
+	 */
+	if (threshold_ns <= 0x3ff * 1) {
+		*scale = 0;		/* Value times 1ns */
+		*value = threshold_ns;
+	} else if (threshold_ns <= 0x3ff * 32) {
+		*scale = 1;		/* Value times 32ns */
+		*value = roundup(threshold_ns, 32) / 32;
+	} else if (threshold_ns <= 0x3ff * 1024) {
+		*scale = 2;		/* Value times 1024ns */
+		*value = roundup(threshold_ns, 1024) / 1024;
+	} else if (threshold_ns <= 0x3ff * 32768) {
+		*scale = 3;		/* Value times 32768ns */
+		*value = roundup(threshold_ns, 32768) / 32768;
+	} else if (threshold_ns <= 0x3ff * 1048576) {
+		*scale = 4;		/* Value times 1048576ns */
+		*value = roundup(threshold_ns, 1048576) / 1048576;
+	} else if (threshold_ns <= 0x3ff * (u64) 33554432) {
+		*scale = 5;		/* Value times 33554432ns */
+		*value = roundup(threshold_ns, 33554432) / 33554432;
+	} else {
+		*scale = 5;
+		*value = 0x3ff;		/* Max representable value */
+	}
+}
+
+static void pcie_aspm_check_latency(struct pci_dev *endpoint)
+{
+	u32 latency, encoding, lnkcap_up, lnkcap_dw;
+	u32 l1_switch_latency = 0, latency_up_l0s;
+	u32 latency_up_l1, latency_dw_l0s, latency_dw_l1;
+	u32 acceptable_l0s, acceptable_l1;
+	struct pcie_link_state *link;
+
+	/* Device not in D0 doesn't need latency check */
+	if ((endpoint->current_state != PCI_D0) &&
+	    (endpoint->current_state != PCI_UNKNOWN))
+		return;
+
+	link = endpoint->bus->self->link_state;
+
+	/* Calculate endpoint L0s acceptable latency */
+	encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L0S) >> 6;
+	acceptable_l0s = calc_l0s_acceptable(encoding);
+
+	/* Calculate endpoint L1 acceptable latency */
+	encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L1) >> 9;
+	acceptable_l1 = calc_l1_acceptable(encoding);
+
+	while (link) {
+		struct pci_dev *dev = pci_function_0(link->pdev->subordinate);
+
+		/* Read direction exit latencies */
+		pcie_capability_read_dword(link->pdev, PCI_EXP_LNKCAP,
+					   &lnkcap_up);
+		pcie_capability_read_dword(dev, PCI_EXP_LNKCAP,
+					   &lnkcap_dw);
+		latency_up_l0s = calc_l0s_latency(lnkcap_up);
+		latency_up_l1 = calc_l1_latency(lnkcap_up);
+		latency_dw_l0s = calc_l0s_latency(lnkcap_dw);
+		latency_dw_l1 = calc_l1_latency(lnkcap_dw);
+
+		/* Check upstream direction L0s latency */
+		if ((link->aspm_capable & ASPM_STATE_L0S_UP) &&
+		    (latency_up_l0s > acceptable_l0s))
+			link->aspm_capable &= ~ASPM_STATE_L0S_UP;
+
+		/* Check downstream direction L0s latency */
+		if ((link->aspm_capable & ASPM_STATE_L0S_DW) &&
+		    (latency_dw_l0s > acceptable_l0s))
+			link->aspm_capable &= ~ASPM_STATE_L0S_DW;
+		/*
+		 * Check L1 latency.
+		 * Every switch on the path to root complex need 1
+		 * more microsecond for L1. Spec doesn't mention L0s.
+		 *
+		 * The exit latencies for L1 substates are not advertised
+		 * by a device.  Since the spec also doesn't mention a way
+		 * to determine max latencies introduced by enabling L1
+		 * substates on the components, it is not clear how to do
+		 * a L1 substate exit latency check.  We assume that the
+		 * L1 exit latencies advertised by a device include L1
+		 * substate latencies (and hence do not do any check).
+		 */
+		latency = max_t(u32, latency_up_l1, latency_dw_l1);
+		if ((link->aspm_capable & ASPM_STATE_L1) &&
+		    (latency + l1_switch_latency > acceptable_l1))
+			link->aspm_capable &= ~ASPM_STATE_L1;
+		l1_switch_latency += 1000;
+
+		link = link->parent;
+	}
+}
+
+static void pci_clear_and_set_dword(struct pci_dev *pdev, int pos,
+				    u32 clear, u32 set)
+{
+	u32 val;
+
+	pci_read_config_dword(pdev, pos, &val);
+	val &= ~clear;
+	val |= set;
+	pci_write_config_dword(pdev, pos, val);
+}
+
+/* Calculate L1.2 PM substate timing parameters */
+static void aspm_calc_l12_info(struct pcie_link_state *link,
+				u32 parent_l1ss_cap, u32 child_l1ss_cap)
+{
+	struct pci_dev *child = link->downstream, *parent = link->pdev;
+	u32 val1, val2, scale1, scale2;
+	u32 t_common_mode, t_power_on, l1_2_threshold, scale, value;
+	u32 ctl1 = 0, ctl2 = 0;
+	u32 pctl1, pctl2, cctl1, cctl2;
+	u32 pl1_2_enables, cl1_2_enables;
+
+	/* Choose the greater of the two Port Common_Mode_Restore_Times */
+	val1 = (parent_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
+	val2 = (child_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
+	t_common_mode = max(val1, val2);
+
+	/* Choose the greater of the two Port T_POWER_ON times */
+	val1   = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
+	scale1 = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
+	val2   = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
+	scale2 = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
+
+	if (calc_l12_pwron(parent, scale1, val1) >
+	    calc_l12_pwron(child, scale2, val2)) {
+		ctl2 |= scale1 | (val1 << 3);
+		t_power_on = calc_l12_pwron(parent, scale1, val1);
+	} else {
+		ctl2 |= scale2 | (val2 << 3);
+		t_power_on = calc_l12_pwron(child, scale2, val2);
+	}
+
+	/*
+	 * Set LTR_L1.2_THRESHOLD to the time required to transition the
+	 * Link from L0 to L1.2 and back to L0 so we enter L1.2 only if
+	 * downstream devices report (via LTR) that they can tolerate at
+	 * least that much latency.
+	 *
+	 * Based on PCIe r3.1, sec 5.5.3.3.1, Figures 5-16 and 5-17, and
+	 * Table 5-11.  T(POWER_OFF) is at most 2us and T(L1.2) is at
+	 * least 4us.
+	 */
+	l1_2_threshold = 2 + 4 + t_common_mode + t_power_on;
+	encode_l12_threshold(l1_2_threshold, &scale, &value);
+	ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
+
+	/* Some broken devices only support dword access to L1 SS */
+	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1, &pctl1);
+	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, &pctl2);
+	pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL1, &cctl1);
+	pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL2, &cctl2);
+
+	if (ctl1 == pctl1 && ctl1 == cctl1 &&
+	    ctl2 == pctl2 && ctl2 == cctl2)
+		return;
+
+	/* Disable L1.2 while updating.  See PCIe r5.0, sec 5.5.4, 7.8.3.3 */
+	pl1_2_enables = pctl1 & PCI_L1SS_CTL1_L1_2_MASK;
+	cl1_2_enables = cctl1 & PCI_L1SS_CTL1_L1_2_MASK;
+
+	if (pl1_2_enables || cl1_2_enables) {
+		pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
+					PCI_L1SS_CTL1_L1_2_MASK, 0);
+		pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+					PCI_L1SS_CTL1_L1_2_MASK, 0);
+	}
+
+	/* Program T_POWER_ON times in both ports */
+	pci_write_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, ctl2);
+	pci_write_config_dword(child, child->l1ss + PCI_L1SS_CTL2, ctl2);
+
+	/* Program Common_Mode_Restore_Time in upstream device */
+	pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_CM_RESTORE_TIME, ctl1);
+
+	/* Program LTR_L1.2_THRESHOLD time in both ports */
+	pci_clear_and_set_dword(parent,	parent->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
+				PCI_L1SS_CTL1_LTR_L12_TH_SCALE, ctl1);
+	pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
+				PCI_L1SS_CTL1_LTR_L12_TH_SCALE, ctl1);
+
+	if (pl1_2_enables || cl1_2_enables) {
+		pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1, 0,
+					pl1_2_enables);
+		pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1, 0,
+					cl1_2_enables);
+	}
+}
+
+static void aspm_l1ss_init(struct pcie_link_state *link)
+{
+	struct pci_dev *child = link->downstream, *parent = link->pdev;
+	u32 parent_l1ss_cap, child_l1ss_cap;
+	u32 parent_l1ss_ctl1 = 0, child_l1ss_ctl1 = 0;
+
+	if (!parent->l1ss || !child->l1ss)
+		return;
+
+	/* Setup L1 substate */
+	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CAP,
+			      &parent_l1ss_cap);
+	pci_read_config_dword(child, child->l1ss + PCI_L1SS_CAP,
+			      &child_l1ss_cap);
+
+	if (!(parent_l1ss_cap & PCI_L1SS_CAP_L1_PM_SS))
+		parent_l1ss_cap = 0;
+	if (!(child_l1ss_cap & PCI_L1SS_CAP_L1_PM_SS))
+		child_l1ss_cap = 0;
+
+	/*
+	 * If we don't have LTR for the entire path from the Root Complex
+	 * to this device, we can't use ASPM L1.2 because it relies on the
+	 * LTR_L1.2_THRESHOLD.  See PCIe r4.0, secs 5.5.4, 6.18.
+	 */
+	if (!child->ltr_path)
+		child_l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
+
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_ASPM_L1_1)
+		link->aspm_support |= ASPM_STATE_L1_1;
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_ASPM_L1_2)
+		link->aspm_support |= ASPM_STATE_L1_2;
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_1)
+		link->aspm_support |= ASPM_STATE_L1_1_PCIPM;
+	if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_2)
+		link->aspm_support |= ASPM_STATE_L1_2_PCIPM;
+
+	if (parent_l1ss_cap)
+		pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				      &parent_l1ss_ctl1);
+	if (child_l1ss_cap)
+		pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL1,
+				      &child_l1ss_ctl1);
+
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
+		link->aspm_enabled |= ASPM_STATE_L1_1;
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
+		link->aspm_enabled |= ASPM_STATE_L1_2;
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
+		link->aspm_enabled |= ASPM_STATE_L1_1_PCIPM;
+	if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
+		link->aspm_enabled |= ASPM_STATE_L1_2_PCIPM;
+
+	if (link->aspm_support & ASPM_STATE_L1_2_MASK)
+		aspm_calc_l12_info(link, parent_l1ss_cap, child_l1ss_cap);
+}
+
+static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
+{
+	struct pci_dev *child = link->downstream, *parent = link->pdev;
+	u32 parent_lnkcap, child_lnkcap;
+	u16 parent_lnkctl, child_lnkctl;
+	struct pci_bus *linkbus = parent->subordinate;
+
+	if (blacklist) {
+		/* Set enabled/disable so that we will disable ASPM later */
+		link->aspm_enabled = ASPM_STATE_ALL;
+		link->aspm_disable = ASPM_STATE_ALL;
+		return;
+	}
+
+	/*
+	 * If ASPM not supported, don't mess with the clocks and link,
+	 * bail out now.
+	 */
+	pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
+	pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
+	if (!(parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPMS))
+		return;
+
+	/* Configure common clock before checking latencies */
+	pcie_aspm_configure_common_clock(link);
+
+	/*
+	 * Re-read upstream/downstream components' register state after
+	 * clock configuration.  L0s & L1 exit latencies in the otherwise
+	 * read-only Link Capabilities may change depending on common clock
+	 * configuration (PCIe r5.0, sec 7.5.3.6).
+	 */
+	pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
+	pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
+	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &parent_lnkctl);
+	pcie_capability_read_word(child, PCI_EXP_LNKCTL, &child_lnkctl);
+
+	/*
+	 * Setup L0s state
+	 *
+	 * Note that we must not enable L0s in either direction on a
+	 * given link unless components on both sides of the link each
+	 * support L0s.
+	 */
+	if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L0S)
+		link->aspm_support |= ASPM_STATE_L0S;
+
+	if (child_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
+		link->aspm_enabled |= ASPM_STATE_L0S_UP;
+	if (parent_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
+		link->aspm_enabled |= ASPM_STATE_L0S_DW;
+
+	/* Setup L1 state */
+	if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L1)
+		link->aspm_support |= ASPM_STATE_L1;
+
+	if (parent_lnkctl & child_lnkctl & PCI_EXP_LNKCTL_ASPM_L1)
+		link->aspm_enabled |= ASPM_STATE_L1;
+
+	aspm_l1ss_init(link);
+
+	/* Save default state */
+	link->aspm_default = link->aspm_enabled;
+
+	/* Setup initial capable state. Will be updated later */
+	link->aspm_capable = link->aspm_support;
+
+	/* Get and check endpoint acceptable latencies */
+	list_for_each_entry(child, &linkbus->devices, bus_list) {
+		if (pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT &&
+		    pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END)
+			continue;
+
+		pcie_aspm_check_latency(child);
+	}
+}
+
+/* Configure the ASPM L1 substates */
+static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
+{
+	u32 val, enable_req;
+	struct pci_dev *child = link->downstream, *parent = link->pdev;
+
+	enable_req = (link->aspm_enabled ^ state) & state;
+
+	/*
+	 * Here are the rules specified in the PCIe spec for enabling L1SS:
+	 * - When enabling L1.x, enable bit at parent first, then at child
+	 * - When disabling L1.x, disable bit at child first, then at parent
+	 * - When enabling ASPM L1.x, need to disable L1
+	 *   (at child followed by parent).
+	 * - The ASPM/PCIPM L1.2 must be disabled while programming timing
+	 *   parameters
+	 *
+	 * To keep it simple, disable all L1SS bits first, and later enable
+	 * what is needed.
+	 */
+
+	/* Disable all L1 substates */
+	pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_L1SS_MASK, 0);
+	pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_L1SS_MASK, 0);
+	/*
+	 * If needed, disable L1, and it gets enabled later
+	 * in pcie_config_aspm_link().
+	 */
+	if (enable_req & (ASPM_STATE_L1_1 | ASPM_STATE_L1_2)) {
+		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_ASPM_L1, 0);
+		pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_ASPM_L1, 0);
+	}
+
+	val = 0;
+	if (state & ASPM_STATE_L1_1)
+		val |= PCI_L1SS_CTL1_ASPM_L1_1;
+	if (state & ASPM_STATE_L1_2)
+		val |= PCI_L1SS_CTL1_ASPM_L1_2;
+	if (state & ASPM_STATE_L1_1_PCIPM)
+		val |= PCI_L1SS_CTL1_PCIPM_L1_1;
+	if (state & ASPM_STATE_L1_2_PCIPM)
+		val |= PCI_L1SS_CTL1_PCIPM_L1_2;
+
+	/* Enable what we need to enable */
+	pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_L1SS_MASK, val);
+	pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
+				PCI_L1SS_CTL1_L1SS_MASK, val);
+}
+
+static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
+{
+	pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
+					   PCI_EXP_LNKCTL_ASPMC, val);
+}
+
+static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)
+{
+	u32 upstream = 0, dwstream = 0;
+	struct pci_dev *child = link->downstream, *parent = link->pdev;
+	struct pci_bus *linkbus = parent->subordinate;
+
+	/* Enable only the states that were not explicitly disabled */
+	state &= (link->aspm_capable & ~link->aspm_disable);
+
+	/* Can't enable any substates if L1 is not enabled */
+	if (!(state & ASPM_STATE_L1))
+		state &= ~ASPM_STATE_L1SS;
+
+	/* Spec says both ports must be in D0 before enabling PCI PM substates*/
+	if (parent->current_state != PCI_D0 || child->current_state != PCI_D0) {
+		state &= ~ASPM_STATE_L1_SS_PCIPM;
+		state |= (link->aspm_enabled & ASPM_STATE_L1_SS_PCIPM);
+	}
+
+	/* Nothing to do if the link is already in the requested state */
+	if (link->aspm_enabled == state)
+		return;
+	/* Convert ASPM state to upstream/downstream ASPM register state */
+	if (state & ASPM_STATE_L0S_UP)
+		dwstream |= PCI_EXP_LNKCTL_ASPM_L0S;
+	if (state & ASPM_STATE_L0S_DW)
+		upstream |= PCI_EXP_LNKCTL_ASPM_L0S;
+	if (state & ASPM_STATE_L1) {
+		upstream |= PCI_EXP_LNKCTL_ASPM_L1;
+		dwstream |= PCI_EXP_LNKCTL_ASPM_L1;
+	}
+
+	if (link->aspm_capable & ASPM_STATE_L1SS)
+		pcie_config_aspm_l1ss(link, state);
+
+	/*
+	 * Spec 2.0 suggests all functions should be configured the
+	 * same setting for ASPM. Enabling ASPM L1 should be done in
+	 * upstream component first and then downstream, and vice
+	 * versa for disabling ASPM L1. Spec doesn't mention L0S.
+	 */
+	if (state & ASPM_STATE_L1)
+		pcie_config_aspm_dev(parent, upstream);
+	list_for_each_entry(child, &linkbus->devices, bus_list)
+		pcie_config_aspm_dev(child, dwstream);
+	if (!(state & ASPM_STATE_L1))
+		pcie_config_aspm_dev(parent, upstream);
+
+	link->aspm_enabled = state;
+}
+
+static void pcie_config_aspm_path(struct pcie_link_state *link)
+{
+	while (link) {
+		pcie_config_aspm_link(link, policy_to_aspm_state(link));
+		link = link->parent;
+	}
+}
+
+static void free_link_state(struct pcie_link_state *link)
+{
+	link->pdev->link_state = NULL;
+	kfree(link);
+}
+
+static int pcie_aspm_sanity_check(struct pci_dev *pdev)
+{
+	struct pci_dev *child;
+	u32 reg32;
+
+	/*
+	 * Some functions in a slot might not all be PCIe functions,
+	 * very strange. Disable ASPM for the whole slot
+	 */
+	list_for_each_entry(child, &pdev->subordinate->devices, bus_list) {
+		if (!pci_is_pcie(child))
+			return -EINVAL;
+
+		/*
+		 * If ASPM is disabled then we're not going to change
+		 * the BIOS state. It's safe to continue even if it's a
+		 * pre-1.1 device
+		 */
+
+		if (aspm_disabled)
+			continue;
+
+		/*
+		 * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
+		 * RBER bit to determine if a function is 1.1 version device
+		 */
+		pcie_capability_read_dword(child, PCI_EXP_DEVCAP, &reg32);
+		if (!(reg32 & PCI_EXP_DEVCAP_RBER) && !aspm_force) {
+			pci_info(child, "disabling ASPM on pre-1.1 PCIe device.  You can enable it with 'pcie_aspm=force'\n");
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev)
+{
+	struct pcie_link_state *link;
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		return NULL;
+
+	INIT_LIST_HEAD(&link->sibling);
+	link->pdev = pdev;
+	link->downstream = pci_function_0(pdev->subordinate);
+
+	/*
+	 * Root Ports and PCI/PCI-X to PCIe Bridges are roots of PCIe
+	 * hierarchies.  Note that some PCIe host implementations omit
+	 * the root ports entirely, in which case a downstream port on
+	 * a switch may become the root of the link state chain for all
+	 * its subordinate endpoints.
+	 */
+	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT ||
+	    pci_pcie_type(pdev) == PCI_EXP_TYPE_PCIE_BRIDGE ||
+	    !pdev->bus->parent->self) {
+		link->root = link;
+	} else {
+		struct pcie_link_state *parent;
+
+		parent = pdev->bus->parent->self->link_state;
+		if (!parent) {
+			kfree(link);
+			return NULL;
+		}
+
+		link->parent = parent;
+		link->root = link->parent->root;
+	}
+
+	list_add(&link->sibling, &link_list);
+	pdev->link_state = link;
+	return link;
+}
+
+static void pcie_aspm_update_sysfs_visibility(struct pci_dev *pdev)
+{
+	struct pci_dev *child;
+
+	list_for_each_entry(child, &pdev->subordinate->devices, bus_list)
+		sysfs_update_group(&child->dev.kobj, &aspm_ctrl_attr_group);
+}
+
+/*
+ * pcie_aspm_init_link_state: Initiate PCI express link state.
+ * It is called after the pcie and its children devices are scanned.
+ * @pdev: the root port or switch downstream port
+ */
+void pcie_aspm_init_link_state(struct pci_dev *pdev)
+{
+	struct pcie_link_state *link;
+	int blacklist = !!pcie_aspm_sanity_check(pdev);
+
+	if (!aspm_support_enabled)
+		return;
+
+	if (pdev->link_state)
+		return;
+
+	/*
+	 * We allocate pcie_link_state for the component on the upstream
+	 * end of a Link, so there's nothing to do unless this device is
+	 * downstream port.
+	 */
+	if (!pcie_downstream_port(pdev))
+		return;
+
+	/* VIA has a strange chipset, root port is under a bridge */
+	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT &&
+	    pdev->bus->self)
+		return;
+
+	down_read(&pci_bus_sem);
+	if (list_empty(&pdev->subordinate->devices))
+		goto out;
+
+	mutex_lock(&aspm_lock);
+	link = alloc_pcie_link_state(pdev);
+	if (!link)
+		goto unlock;
+	/*
+	 * Setup initial ASPM state. Note that we need to configure
+	 * upstream links also because capable state of them can be
+	 * update through pcie_aspm_cap_init().
+	 */
+	pcie_aspm_cap_init(link, blacklist);
+
+	/* Setup initial Clock PM state */
+	pcie_clkpm_cap_init(link, blacklist);
+
+	/*
+	 * At this stage drivers haven't had an opportunity to change the
+	 * link policy setting. Enabling ASPM on broken hardware can cripple
+	 * it even before the driver has had a chance to disable ASPM, so
+	 * default to a safe level right now. If we're enabling ASPM beyond
+	 * the BIOS's expectation, we'll do so once pci_enable_device() is
+	 * called.
+	 */
+	if (aspm_policy != POLICY_POWERSAVE &&
+	    aspm_policy != POLICY_POWER_SUPERSAVE) {
+		pcie_config_aspm_path(link);
+		pcie_set_clkpm(link, policy_to_clkpm_state(link));
+	}
+
+	pcie_aspm_update_sysfs_visibility(pdev);
+
+unlock:
+	mutex_unlock(&aspm_lock);
+out:
+	up_read(&pci_bus_sem);
+}
+
+/* Recheck latencies and update aspm_capable for links under the root */
+static void pcie_update_aspm_capable(struct pcie_link_state *root)
+{
+	struct pcie_link_state *link;
+	BUG_ON(root->parent);
+	list_for_each_entry(link, &link_list, sibling) {
+		if (link->root != root)
+			continue;
+		link->aspm_capable = link->aspm_support;
+	}
+	list_for_each_entry(link, &link_list, sibling) {
+		struct pci_dev *child;
+		struct pci_bus *linkbus = link->pdev->subordinate;
+		if (link->root != root)
+			continue;
+		list_for_each_entry(child, &linkbus->devices, bus_list) {
+			if ((pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT) &&
+			    (pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END))
+				continue;
+			pcie_aspm_check_latency(child);
+		}
+	}
+}
+
+/* @pdev: the endpoint device */
+void pcie_aspm_exit_link_state(struct pci_dev *pdev)
+{
+	struct pci_dev *parent = pdev->bus->self;
+	struct pcie_link_state *link, *root, *parent_link;
+
+	if (!parent || !parent->link_state)
+		return;
+
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+
+	link = parent->link_state;
+	root = link->root;
+	parent_link = link->parent;
+
+	/*
+	 * link->downstream is a pointer to the pci_dev of function 0.  If
+	 * we remove that function, the pci_dev is about to be deallocated,
+	 * so we can't use link->downstream again.  Free the link state to
+	 * avoid this.
+	 *
+	 * If we're removing a non-0 function, it's possible we could
+	 * retain the link state, but PCIe r6.0, sec 7.5.3.7, recommends
+	 * programming the same ASPM Control value for all functions of
+	 * multi-function devices, so disable ASPM for all of them.
+	 */
+	pcie_config_aspm_link(link, 0);
+	list_del(&link->sibling);
+	free_link_state(link);
+
+	/* Recheck latencies and configure upstream links */
+	if (parent_link) {
+		pcie_update_aspm_capable(root);
+		pcie_config_aspm_path(parent_link);
+	}
+
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+}
+
+/* @pdev: the root port or switch downstream port */
+void pcie_aspm_pm_state_change(struct pci_dev *pdev)
+{
+	struct pcie_link_state *link = pdev->link_state;
+
+	if (aspm_disabled || !link)
+		return;
+	/*
+	 * Devices changed PM state, we should recheck if latency
+	 * meets all functions' requirement
+	 */
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+	pcie_update_aspm_capable(link->root);
+	pcie_config_aspm_path(link);
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+}
+
+void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
+{
+	struct pcie_link_state *link = pdev->link_state;
+
+	if (aspm_disabled || !link)
+		return;
+
+	if (aspm_policy != POLICY_POWERSAVE &&
+	    aspm_policy != POLICY_POWER_SUPERSAVE)
+		return;
+
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+	pcie_config_aspm_path(link);
+	pcie_set_clkpm(link, policy_to_clkpm_state(link));
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+}
+
+static struct pcie_link_state *pcie_aspm_get_link(struct pci_dev *pdev)
+{
+	struct pci_dev *bridge;
+
+	if (!pci_is_pcie(pdev))
+		return NULL;
+
+	bridge = pci_upstream_bridge(pdev);
+	if (!bridge || !pci_is_pcie(bridge))
+		return NULL;
+
+	return bridge->link_state;
+}
+
+static int __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
+{
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+
+	if (!link)
+		return -EINVAL;
+	/*
+	 * A driver requested that ASPM be disabled 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.  Windows has
+	 * a similar mechanism using "PciASPMOptOut", which is also
+	 * ignored in this situation.
+	 */
+	if (aspm_disabled) {
+		pci_warn(pdev, "can't disable ASPM; OS doesn't have ASPM control\n");
+		return -EPERM;
+	}
+
+	if (sem)
+		down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+	if (state & PCIE_LINK_STATE_L0S)
+		link->aspm_disable |= ASPM_STATE_L0S;
+	if (state & PCIE_LINK_STATE_L1)
+		/* L1 PM substates require L1 */
+		link->aspm_disable |= ASPM_STATE_L1 | ASPM_STATE_L1SS;
+	if (state & PCIE_LINK_STATE_L1_1)
+		link->aspm_disable |= ASPM_STATE_L1_1;
+	if (state & PCIE_LINK_STATE_L1_2)
+		link->aspm_disable |= ASPM_STATE_L1_2;
+	if (state & PCIE_LINK_STATE_L1_1_PCIPM)
+		link->aspm_disable |= ASPM_STATE_L1_1_PCIPM;
+	if (state & PCIE_LINK_STATE_L1_2_PCIPM)
+		link->aspm_disable |= ASPM_STATE_L1_2_PCIPM;
+	pcie_config_aspm_link(link, policy_to_aspm_state(link));
+
+	if (state & PCIE_LINK_STATE_CLKPM)
+		link->clkpm_disable = 1;
+	pcie_set_clkpm(link, policy_to_clkpm_state(link));
+	mutex_unlock(&aspm_lock);
+	if (sem)
+		up_read(&pci_bus_sem);
+
+	return 0;
+}
+
+int pci_disable_link_state_locked(struct pci_dev *pdev, int state)
+{
+	return __pci_disable_link_state(pdev, state, false);
+}
+EXPORT_SYMBOL(pci_disable_link_state_locked);
+
+/**
+ * pci_disable_link_state - Disable device's link state, so the link will
+ * never enter specific 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. Returns 0 or a negative errno.
+ *
+ * @pdev: PCI device
+ * @state: ASPM link state to disable
+ */
+int pci_disable_link_state(struct pci_dev *pdev, int state)
+{
+	return __pci_disable_link_state(pdev, state, true);
+}
+EXPORT_SYMBOL(pci_disable_link_state);
+
+static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked)
+{
+	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;
+	}
+
+	if (!locked)
+		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)
+		link->aspm_default |= ASPM_STATE_L1;
+	/* L1 PM substates require L1 */
+	if (state & PCIE_LINK_STATE_L1_1)
+		link->aspm_default |= ASPM_STATE_L1_1 | ASPM_STATE_L1;
+	if (state & PCIE_LINK_STATE_L1_2)
+		link->aspm_default |= ASPM_STATE_L1_2 | ASPM_STATE_L1;
+	if (state & PCIE_LINK_STATE_L1_1_PCIPM)
+		link->aspm_default |= ASPM_STATE_L1_1_PCIPM | ASPM_STATE_L1;
+	if (state & PCIE_LINK_STATE_L1_2_PCIPM)
+		link->aspm_default |= ASPM_STATE_L1_2_PCIPM | ASPM_STATE_L1;
+	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);
+	if (!locked)
+		up_read(&pci_bus_sem);
+
+	return 0;
+}
+
+/**
+ * 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)
+{
+	return __pci_enable_link_state(pdev, state, false);
+}
+EXPORT_SYMBOL(pci_enable_link_state);
+
+/**
+ * pci_enable_link_state_locked - 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
+ *
+ * Context: Caller holds pci_bus_sem read lock.
+ */
+int pci_enable_link_state_locked(struct pci_dev *pdev, int state)
+{
+	lockdep_assert_held_read(&pci_bus_sem);
+
+	return __pci_enable_link_state(pdev, state, true);
+}
+EXPORT_SYMBOL(pci_enable_link_state_locked);
+
+static int pcie_aspm_set_policy(const char *val,
+				const struct kernel_param *kp)
+{
+	int i;
+	struct pcie_link_state *link;
+
+	if (aspm_disabled)
+		return -EPERM;
+	i = sysfs_match_string(policy_str, val);
+	if (i < 0)
+		return i;
+	if (i == aspm_policy)
+		return 0;
+
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+	aspm_policy = i;
+	list_for_each_entry(link, &link_list, sibling) {
+		pcie_config_aspm_link(link, policy_to_aspm_state(link));
+		pcie_set_clkpm(link, policy_to_clkpm_state(link));
+	}
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+	return 0;
+}
+
+static int pcie_aspm_get_policy(char *buffer, const struct kernel_param *kp)
+{
+	int i, cnt = 0;
+	for (i = 0; i < ARRAY_SIZE(policy_str); i++)
+		if (i == aspm_policy)
+			cnt += sprintf(buffer + cnt, "[%s] ", policy_str[i]);
+		else
+			cnt += sprintf(buffer + cnt, "%s ", policy_str[i]);
+	cnt += sprintf(buffer + cnt, "\n");
+	return cnt;
+}
+
+module_param_call(policy, pcie_aspm_set_policy, pcie_aspm_get_policy,
+	NULL, 0644);
+
+/**
+ * pcie_aspm_enabled - Check if PCIe ASPM has been enabled for a device.
+ * @pdev: Target device.
+ *
+ * Relies on the upstream bridge's link_state being valid.  The link_state
+ * is deallocated only when the last child of the bridge (i.e., @pdev or a
+ * sibling) is removed, and the caller should be holding a reference to
+ * @pdev, so this should be safe.
+ */
+bool pcie_aspm_enabled(struct pci_dev *pdev)
+{
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+
+	if (!link)
+		return false;
+
+	return link->aspm_enabled;
+}
+EXPORT_SYMBOL_GPL(pcie_aspm_enabled);
+
+static ssize_t aspm_attr_show_common(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf, u8 state)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+
+	return sysfs_emit(buf, "%d\n", (link->aspm_enabled & state) ? 1 : 0);
+}
+
+static ssize_t aspm_attr_store_common(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t len, u8 state)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+	bool state_enable;
+
+	if (kstrtobool(buf, &state_enable) < 0)
+		return -EINVAL;
+
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+
+	if (state_enable) {
+		link->aspm_disable &= ~state;
+		/* need to enable L1 for substates */
+		if (state & ASPM_STATE_L1SS)
+			link->aspm_disable &= ~ASPM_STATE_L1;
+	} else {
+		link->aspm_disable |= state;
+		if (state & ASPM_STATE_L1)
+			link->aspm_disable |= ASPM_STATE_L1SS;
+	}
+
+	pcie_config_aspm_link(link, policy_to_aspm_state(link));
+
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+
+	return len;
+}
+
+#define ASPM_ATTR(_f, _s)						\
+static ssize_t _f##_show(struct device *dev,				\
+			 struct device_attribute *attr, char *buf)	\
+{ return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_##_s); }	\
+									\
+static ssize_t _f##_store(struct device *dev,				\
+			  struct device_attribute *attr,		\
+			  const char *buf, size_t len)			\
+{ return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_##_s); }
+
+ASPM_ATTR(l0s_aspm, L0S)
+ASPM_ATTR(l1_aspm, L1)
+ASPM_ATTR(l1_1_aspm, L1_1)
+ASPM_ATTR(l1_2_aspm, L1_2)
+ASPM_ATTR(l1_1_pcipm, L1_1_PCIPM)
+ASPM_ATTR(l1_2_pcipm, L1_2_PCIPM)
+
+static ssize_t clkpm_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+
+	return sysfs_emit(buf, "%d\n", link->clkpm_enabled);
+}
+
+static ssize_t clkpm_store(struct device *dev,
+			   struct device_attribute *attr,
+			   const char *buf, size_t len)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+	bool state_enable;
+
+	if (kstrtobool(buf, &state_enable) < 0)
+		return -EINVAL;
+
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+
+	link->clkpm_disable = !state_enable;
+	pcie_set_clkpm(link, policy_to_clkpm_state(link));
+
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+
+	return len;
+}
+
+static DEVICE_ATTR_RW(clkpm);
+static DEVICE_ATTR_RW(l0s_aspm);
+static DEVICE_ATTR_RW(l1_aspm);
+static DEVICE_ATTR_RW(l1_1_aspm);
+static DEVICE_ATTR_RW(l1_2_aspm);
+static DEVICE_ATTR_RW(l1_1_pcipm);
+static DEVICE_ATTR_RW(l1_2_pcipm);
+
+static struct attribute *aspm_ctrl_attrs[] = {
+	&dev_attr_clkpm.attr,
+	&dev_attr_l0s_aspm.attr,
+	&dev_attr_l1_aspm.attr,
+	&dev_attr_l1_1_aspm.attr,
+	&dev_attr_l1_2_aspm.attr,
+	&dev_attr_l1_1_pcipm.attr,
+	&dev_attr_l1_2_pcipm.attr,
+	NULL
+};
+
+static umode_t aspm_ctrl_attrs_are_visible(struct kobject *kobj,
+					   struct attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
+	static const u8 aspm_state_map[] = {
+		ASPM_STATE_L0S,
+		ASPM_STATE_L1,
+		ASPM_STATE_L1_1,
+		ASPM_STATE_L1_2,
+		ASPM_STATE_L1_1_PCIPM,
+		ASPM_STATE_L1_2_PCIPM,
+	};
+
+	if (aspm_disabled || !link)
+		return 0;
+
+	if (n == 0)
+		return link->clkpm_capable ? a->mode : 0;
+
+	return link->aspm_capable & aspm_state_map[n - 1] ? a->mode : 0;
+}
+
+const struct attribute_group aspm_ctrl_attr_group = {
+	.name = "link",
+	.attrs = aspm_ctrl_attrs,
+	.is_visible = aspm_ctrl_attrs_are_visible,
+};
+
+static int __init pcie_aspm_disable(char *str)
+{
+	if (!strcmp(str, "off")) {
+		aspm_policy = POLICY_DEFAULT;
+		aspm_disabled = 1;
+		aspm_support_enabled = false;
+		printk(KERN_INFO "PCIe ASPM is disabled\n");
+	} else if (!strcmp(str, "force")) {
+		aspm_force = 1;
+		printk(KERN_INFO "PCIe ASPM is forcibly enabled\n");
+	}
+	return 1;
+}
+
+__setup("pcie_aspm=", pcie_aspm_disable);
+
+void pcie_no_aspm(void)
+{
+	/*
+	 * Disabling ASPM is intended to prevent the kernel from modifying
+	 * existing hardware state, not to clear existing state. To that end:
+	 * (a) set policy to POLICY_DEFAULT in order to avoid changing state
+	 * (b) prevent userspace from changing policy
+	 */
+	if (!aspm_force) {
+		aspm_policy = POLICY_DEFAULT;
+		aspm_disabled = 1;
+	}
+}
+
+bool pcie_aspm_support_enabled(void)
+{
+	return aspm_support_enabled;
+}