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WSL2-Linux-Kernel/drivers/pci/pcie/aspm.c

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// 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/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 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 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 */
/* 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];
/* L1 PM Substate info */
struct {
u32 up_cap_ptr; /* L1SS cap ptr in upstream dev */
u32 dw_cap_ptr; /* L1SS cap ptr in downstream dev */
u32 ctl1; /* value to be programmed in ctl1 */
u32 ctl2; /* value to be programmed in ctl2 */
} l1ss;
};
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"
};
#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_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;
}
static bool pcie_retrain_link(struct pcie_link_state *link)
{
struct pci_dev *parent = link->pdev;
unsigned long end_jiffies;
u16 reg16;
pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
reg16 |= PCI_EXP_LNKCTL_RL;
pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
if (parent->clear_retrain_link) {
/*
* Due to an erratum in some devices the Retrain Link bit
* needs to be cleared again manually to allow the link
* training to succeed.
*/
reg16 &= ~PCI_EXP_LNKCTL_RL;
pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
}
/* Wait for link training end. Break out after waiting for timeout */
end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
do {
pcie_capability_read_word(parent, PCI_EXP_LNKSTA, &reg16);
if (!(reg16 & PCI_EXP_LNKSTA_LT))
break;
msleep(1);
} while (time_before(jiffies, end_jiffies));
return !(reg16 & PCI_EXP_LNKSTA_LT);
}
/*
* 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, parent_reg, child_reg[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);
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");
}
/* Configure downstream component, all functions */
list_for_each_entry(child, &linkbus->devices, bus_list) {
pcie_capability_read_word(child, PCI_EXP_LNKCTL, &reg16);
child_reg[PCI_FUNC(child->devfn)] = reg16;
if (same_clock)
reg16 |= PCI_EXP_LNKCTL_CCC;
else
reg16 &= ~PCI_EXP_LNKCTL_CCC;
pcie_capability_write_word(child, PCI_EXP_LNKCTL, reg16);
}
/* Configure upstream component */
pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
parent_reg = reg16;
if (same_clock)
reg16 |= PCI_EXP_LNKCTL_CCC;
else
reg16 &= ~PCI_EXP_LNKCTL_CCC;
pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
if (pcie_retrain_link(link))
return;
/* 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_write_word(child, PCI_EXP_LNKCTL,
child_reg[PCI_FUNC(child->devfn)]);
pcie_capability_write_word(parent, PCI_EXP_LNKCTL, parent_reg);
}
/* Convert L0s latency encoding to ns */
static u32 calc_l0s_latency(u32 encoding)
{
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 encoding)
{
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_l1ss_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;
}
static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
{
u32 threshold_ns = threshold_us * 1000;
/* See PCIe r3.1, sec 7.33.3 and sec 6.18 */
if (threshold_ns < 32) {
*scale = 0;
*value = threshold_ns;
} else if (threshold_ns < 1024) {
*scale = 1;
*value = threshold_ns >> 5;
} else if (threshold_ns < 32768) {
*scale = 2;
*value = threshold_ns >> 10;
} else if (threshold_ns < 1048576) {
*scale = 3;
*value = threshold_ns >> 15;
} else if (threshold_ns < 33554432) {
*scale = 4;
*value = threshold_ns >> 20;
} else {
*scale = 5;
*value = threshold_ns >> 25;
}
}
struct aspm_register_info {
u32 support:2;
u32 enabled:2;
u32 latency_encoding_l0s;
u32 latency_encoding_l1;
/* L1 substates */
u32 l1ss_cap_ptr;
u32 l1ss_cap;
u32 l1ss_ctl1;
u32 l1ss_ctl2;
};
static void pcie_get_aspm_reg(struct pci_dev *pdev,
struct aspm_register_info *info)
{
u16 reg16;
u32 reg32;
pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, &reg32);
info->support = (reg32 & PCI_EXP_LNKCAP_ASPMS) >> 10;
info->latency_encoding_l0s = (reg32 & PCI_EXP_LNKCAP_L0SEL) >> 12;
info->latency_encoding_l1 = (reg32 & PCI_EXP_LNKCAP_L1EL) >> 15;
pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &reg16);
info->enabled = reg16 & PCI_EXP_LNKCTL_ASPMC;
/* Read L1 PM substate capabilities */
info->l1ss_cap = info->l1ss_ctl1 = info->l1ss_ctl2 = 0;
info->l1ss_cap_ptr = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_L1SS);
if (!info->l1ss_cap_ptr)
return;
pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CAP,
&info->l1ss_cap);
if (!(info->l1ss_cap & PCI_L1SS_CAP_L1_PM_SS)) {
info->l1ss_cap = 0;
return;
}
/*
* 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 (!pdev->ltr_path)
info->l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL1,
&info->l1ss_ctl1);
pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL2,
&info->l1ss_ctl2);
}
static void pcie_aspm_check_latency(struct pci_dev *endpoint)
{
u32 latency, l1_switch_latency = 0;
struct aspm_latency *acceptable;
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;
acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)];
while (link) {
/* Check upstream direction L0s latency */
if ((link->aspm_capable & ASPM_STATE_L0S_UP) &&
(link->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) &&
(link->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, link->latency_up.l1, link->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;
}
}
/*
* 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;
}
/* Calculate L1.2 PM substate timing parameters */
static void aspm_calc_l1ss_info(struct pcie_link_state *link,
struct aspm_register_info *upreg,
struct aspm_register_info *dwreg)
{
u32 val1, val2, scale1, scale2;
u32 t_common_mode, t_power_on, l1_2_threshold, scale, value;
link->l1ss.up_cap_ptr = upreg->l1ss_cap_ptr;
link->l1ss.dw_cap_ptr = dwreg->l1ss_cap_ptr;
link->l1ss.ctl1 = link->l1ss.ctl2 = 0;
if (!(link->aspm_support & ASPM_STATE_L1_2_MASK))
return;
/* Choose the greater of the two Port Common_Mode_Restore_Times */
val1 = (upreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
val2 = (dwreg->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 = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
scale1 = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
val2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
scale2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
if (calc_l1ss_pwron(link->pdev, scale1, val1) >
calc_l1ss_pwron(link->downstream, scale2, val2)) {
link->l1ss.ctl2 |= scale1 | (val1 << 3);
t_power_on = calc_l1ss_pwron(link->pdev, scale1, val1);
} else {
link->l1ss.ctl2 |= scale2 | (val2 << 3);
t_power_on = calc_l1ss_pwron(link->downstream, 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);
link->l1ss.ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
}
static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
{
struct pci_dev *child = link->downstream, *parent = link->pdev;
struct pci_bus *linkbus = parent->subordinate;
struct aspm_register_info upreg, dwreg;
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;
}
/* Get upstream/downstream components' register state */
pcie_get_aspm_reg(parent, &upreg);
pcie_get_aspm_reg(child, &dwreg);
/*
* If ASPM not supported, don't mess with the clocks and link,
* bail out now.
*/
if (!(upreg.support & dwreg.support))
return;
/* Configure common clock before checking latencies */
pcie_aspm_configure_common_clock(link);
/*
* Re-read upstream/downstream components' register state
* after clock configuration
*/
pcie_get_aspm_reg(parent, &upreg);
pcie_get_aspm_reg(child, &dwreg);
/*
* 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 (dwreg.support & upreg.support & PCIE_LINK_STATE_L0S)
link->aspm_support |= ASPM_STATE_L0S;
if (dwreg.enabled & PCIE_LINK_STATE_L0S)
link->aspm_enabled |= ASPM_STATE_L0S_UP;
if (upreg.enabled & PCIE_LINK_STATE_L0S)
link->aspm_enabled |= ASPM_STATE_L0S_DW;
link->latency_up.l0s = calc_l0s_latency(upreg.latency_encoding_l0s);
link->latency_dw.l0s = calc_l0s_latency(dwreg.latency_encoding_l0s);
/* Setup L1 state */
if (upreg.support & dwreg.support & PCIE_LINK_STATE_L1)
link->aspm_support |= ASPM_STATE_L1;
if (upreg.enabled & dwreg.enabled & PCIE_LINK_STATE_L1)
link->aspm_enabled |= ASPM_STATE_L1;
link->latency_up.l1 = calc_l1_latency(upreg.latency_encoding_l1);
link->latency_dw.l1 = calc_l1_latency(dwreg.latency_encoding_l1);
/* Setup L1 substate */
if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_ASPM_L1_1)
link->aspm_support |= ASPM_STATE_L1_1;
if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_ASPM_L1_2)
link->aspm_support |= ASPM_STATE_L1_2;
if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_1)
link->aspm_support |= ASPM_STATE_L1_1_PCIPM;
if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_2)
link->aspm_support |= ASPM_STATE_L1_2_PCIPM;
if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
link->aspm_enabled |= ASPM_STATE_L1_1;
if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
link->aspm_enabled |= ASPM_STATE_L1_2;
if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
link->aspm_enabled |= ASPM_STATE_L1_1_PCIPM;
if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
link->aspm_enabled |= ASPM_STATE_L1_2_PCIPM;
if (link->aspm_support & ASPM_STATE_L1SS)
aspm_calc_l1ss_info(link, &upreg, &dwreg);
/* 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) {
u32 reg32, encoding;
struct aspm_latency *acceptable =
&link->acceptable[PCI_FUNC(child->devfn)];
if (pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT &&
pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END)
continue;
pcie_capability_read_dword(child, PCI_EXP_DEVCAP, &reg32);
/* Calculate endpoint L0s acceptable latency */
encoding = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6;
acceptable->l0s = calc_l0s_acceptable(encoding);
/* Calculate endpoint L1 acceptable latency */
encoding = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
acceptable->l1 = calc_l1_acceptable(encoding);
pcie_aspm_check_latency(child);
}
}
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);
}
/* 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;
u32 up_cap_ptr = link->l1ss.up_cap_ptr;
u32 dw_cap_ptr = link->l1ss.dw_cap_ptr;
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, dw_cap_ptr + PCI_L1SS_CTL1,
PCI_L1SS_CTL1_L1SS_MASK, 0);
pci_clear_and_set_dword(parent, up_cap_ptr + 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);
}
if (enable_req & ASPM_STATE_L1_2_MASK) {
/* Program T_POWER_ON times in both ports */
pci_write_config_dword(parent, up_cap_ptr + PCI_L1SS_CTL2,
link->l1ss.ctl2);
pci_write_config_dword(child, dw_cap_ptr + PCI_L1SS_CTL2,
link->l1ss.ctl2);
/* Program Common_Mode_Restore_Time in upstream device */
pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
PCI_L1SS_CTL1_CM_RESTORE_TIME,
link->l1ss.ctl1);
/* Program LTR_L1.2_THRESHOLD time in both ports */
pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
PCI_L1SS_CTL1_LTR_L12_TH_SCALE,
link->l1ss.ctl1);
pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
PCI_L1SS_CTL1_LTR_L12_TH_SCALE,
link->l1ss.ctl1);
}
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, up_cap_ptr + PCI_L1SS_CTL1,
PCI_L1SS_CTL1_L1SS_MASK, val);
pci_clear_and_set_dword(child, dw_cap_ptr + 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);
/*
* All PCIe functions are in one slot, remove one function will remove
* the whole slot, so just wait until we are the last function left.
*/
if (!list_empty(&parent->subordinate->devices))
goto out;
link = parent->link_state;
root = link->root;
parent_link = link->parent;
/* All functions are removed, so just disable ASPM for the link */
pcie_config_aspm_link(link, 0);
list_del(&link->sibling);
/* Clock PM is for endpoint device */
free_link_state(link);
/* Recheck latencies and configure upstream links */
if (parent_link) {
pcie_update_aspm_capable(root);
pcie_config_aspm_path(parent_link);
}
out:
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 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 sprintf(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 (strtobool(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;
}
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 sprintf(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 (strtobool(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;
}
EXPORT_SYMBOL(pcie_aspm_support_enabled);
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