1 // SPDX-License-Identifier: GPL-2.0
3 * Enable PCIe link L0s/L1 state and Clock Power Management
5 * Copyright (C) 2007 Intel
6 * Copyright (C) Zhang Yanmin (yanmin.zhang@intel.com)
7 * Copyright (C) Shaohua Li (shaohua.li@intel.com)
10 #include <linux/kernel.h>
11 #include <linux/math.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/pci.h>
15 #include <linux/pci_regs.h>
16 #include <linux/errno.h>
18 #include <linux/init.h>
19 #include <linux/slab.h>
20 #include <linux/jiffies.h>
21 #include <linux/delay.h>
24 #ifdef MODULE_PARAM_PREFIX
25 #undef MODULE_PARAM_PREFIX
27 #define MODULE_PARAM_PREFIX "pcie_aspm."
29 /* Note: those are not register definitions */
30 #define ASPM_STATE_L0S_UP (1) /* Upstream direction L0s state */
31 #define ASPM_STATE_L0S_DW (2) /* Downstream direction L0s state */
32 #define ASPM_STATE_L1 (4) /* L1 state */
33 #define ASPM_STATE_L1_1 (8) /* ASPM L1.1 state */
34 #define ASPM_STATE_L1_2 (0x10) /* ASPM L1.2 state */
35 #define ASPM_STATE_L1_1_PCIPM (0x20) /* PCI PM L1.1 state */
36 #define ASPM_STATE_L1_2_PCIPM (0x40) /* PCI PM L1.2 state */
37 #define ASPM_STATE_L1_SS_PCIPM (ASPM_STATE_L1_1_PCIPM | ASPM_STATE_L1_2_PCIPM)
38 #define ASPM_STATE_L1_2_MASK (ASPM_STATE_L1_2 | ASPM_STATE_L1_2_PCIPM)
39 #define ASPM_STATE_L1SS (ASPM_STATE_L1_1 | ASPM_STATE_L1_1_PCIPM |\
41 #define ASPM_STATE_L0S (ASPM_STATE_L0S_UP | ASPM_STATE_L0S_DW)
42 #define ASPM_STATE_ALL (ASPM_STATE_L0S | ASPM_STATE_L1 | \
45 struct pcie_link_state {
46 struct pci_dev *pdev; /* Upstream component of the Link */
47 struct pci_dev *downstream; /* Downstream component, function 0 */
48 struct pcie_link_state *root; /* pointer to the root port link */
49 struct pcie_link_state *parent; /* pointer to the parent Link state */
50 struct list_head sibling; /* node in link_list */
53 u32 aspm_support:7; /* Supported ASPM state */
54 u32 aspm_enabled:7; /* Enabled ASPM state */
55 u32 aspm_capable:7; /* Capable ASPM state with latency */
56 u32 aspm_default:7; /* Default ASPM state by BIOS */
57 u32 aspm_disable:7; /* Disabled ASPM state */
60 u32 clkpm_capable:1; /* Clock PM capable? */
61 u32 clkpm_enabled:1; /* Current Clock PM state */
62 u32 clkpm_default:1; /* Default Clock PM state by BIOS */
63 u32 clkpm_disable:1; /* Clock PM disabled */
66 static int aspm_disabled, aspm_force;
67 static bool aspm_support_enabled = true;
68 static DEFINE_MUTEX(aspm_lock);
69 static LIST_HEAD(link_list);
71 #define POLICY_DEFAULT 0 /* BIOS default setting */
72 #define POLICY_PERFORMANCE 1 /* high performance */
73 #define POLICY_POWERSAVE 2 /* high power saving */
74 #define POLICY_POWER_SUPERSAVE 3 /* possibly even more power saving */
76 #ifdef CONFIG_PCIEASPM_PERFORMANCE
77 static int aspm_policy = POLICY_PERFORMANCE;
78 #elif defined CONFIG_PCIEASPM_POWERSAVE
79 static int aspm_policy = POLICY_POWERSAVE;
80 #elif defined CONFIG_PCIEASPM_POWER_SUPERSAVE
81 static int aspm_policy = POLICY_POWER_SUPERSAVE;
83 static int aspm_policy;
86 static const char *policy_str[] = {
87 [POLICY_DEFAULT] = "default",
88 [POLICY_PERFORMANCE] = "performance",
89 [POLICY_POWERSAVE] = "powersave",
90 [POLICY_POWER_SUPERSAVE] = "powersupersave"
93 #define LINK_RETRAIN_TIMEOUT HZ
96 * The L1 PM substate capability is only implemented in function 0 in a
97 * multi function device.
99 static struct pci_dev *pci_function_0(struct pci_bus *linkbus)
101 struct pci_dev *child;
103 list_for_each_entry(child, &linkbus->devices, bus_list)
104 if (PCI_FUNC(child->devfn) == 0)
109 static int policy_to_aspm_state(struct pcie_link_state *link)
111 switch (aspm_policy) {
112 case POLICY_PERFORMANCE:
113 /* Disable ASPM and Clock PM */
115 case POLICY_POWERSAVE:
116 /* Enable ASPM L0s/L1 */
117 return (ASPM_STATE_L0S | ASPM_STATE_L1);
118 case POLICY_POWER_SUPERSAVE:
119 /* Enable Everything */
120 return ASPM_STATE_ALL;
122 return link->aspm_default;
127 static int policy_to_clkpm_state(struct pcie_link_state *link)
129 switch (aspm_policy) {
130 case POLICY_PERFORMANCE:
131 /* Disable ASPM and Clock PM */
133 case POLICY_POWERSAVE:
134 case POLICY_POWER_SUPERSAVE:
135 /* Enable Clock PM */
138 return link->clkpm_default;
143 static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
145 struct pci_dev *child;
146 struct pci_bus *linkbus = link->pdev->subordinate;
147 u32 val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
149 list_for_each_entry(child, &linkbus->devices, bus_list)
150 pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
151 PCI_EXP_LNKCTL_CLKREQ_EN,
153 link->clkpm_enabled = !!enable;
156 static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
159 * Don't enable Clock PM if the link is not Clock PM capable
160 * or Clock PM is disabled
162 if (!link->clkpm_capable || link->clkpm_disable)
164 /* Need nothing if the specified equals to current state */
165 if (link->clkpm_enabled == enable)
167 pcie_set_clkpm_nocheck(link, enable);
170 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
172 int capable = 1, enabled = 1;
175 struct pci_dev *child;
176 struct pci_bus *linkbus = link->pdev->subordinate;
178 /* All functions should have the same cap and state, take the worst */
179 list_for_each_entry(child, &linkbus->devices, bus_list) {
180 pcie_capability_read_dword(child, PCI_EXP_LNKCAP, ®32);
181 if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
186 pcie_capability_read_word(child, PCI_EXP_LNKCTL, ®16);
187 if (!(reg16 & PCI_EXP_LNKCTL_CLKREQ_EN))
190 link->clkpm_enabled = enabled;
191 link->clkpm_default = enabled;
192 link->clkpm_capable = capable;
193 link->clkpm_disable = blacklist ? 1 : 0;
196 static bool pcie_retrain_link(struct pcie_link_state *link)
198 struct pci_dev *parent = link->pdev;
199 unsigned long end_jiffies;
202 pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16);
203 reg16 |= PCI_EXP_LNKCTL_RL;
204 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
205 if (parent->clear_retrain_link) {
207 * Due to an erratum in some devices the Retrain Link bit
208 * needs to be cleared again manually to allow the link
209 * training to succeed.
211 reg16 &= ~PCI_EXP_LNKCTL_RL;
212 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
215 /* Wait for link training end. Break out after waiting for timeout */
216 end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
218 pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16);
219 if (!(reg16 & PCI_EXP_LNKSTA_LT))
222 } while (time_before(jiffies, end_jiffies));
223 return !(reg16 & PCI_EXP_LNKSTA_LT);
227 * pcie_aspm_configure_common_clock: check if the 2 ends of a link
228 * could use common clock. If they are, configure them to use the
229 * common clock. That will reduce the ASPM state exit latency.
231 static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
234 u16 reg16, parent_reg, child_reg[8];
235 struct pci_dev *child, *parent = link->pdev;
236 struct pci_bus *linkbus = parent->subordinate;
238 * All functions of a slot should have the same Slot Clock
239 * Configuration, so just check one function
241 child = list_entry(linkbus->devices.next, struct pci_dev, bus_list);
242 BUG_ON(!pci_is_pcie(child));
244 /* Check downstream component if bit Slot Clock Configuration is 1 */
245 pcie_capability_read_word(child, PCI_EXP_LNKSTA, ®16);
246 if (!(reg16 & PCI_EXP_LNKSTA_SLC))
249 /* Check upstream component if bit Slot Clock Configuration is 1 */
250 pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16);
251 if (!(reg16 & PCI_EXP_LNKSTA_SLC))
254 /* Port might be already in common clock mode */
255 pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16);
256 if (same_clock && (reg16 & PCI_EXP_LNKCTL_CCC)) {
257 bool consistent = true;
259 list_for_each_entry(child, &linkbus->devices, bus_list) {
260 pcie_capability_read_word(child, PCI_EXP_LNKCTL,
262 if (!(reg16 & PCI_EXP_LNKCTL_CCC)) {
269 pci_info(parent, "ASPM: current common clock configuration is inconsistent, reconfiguring\n");
272 /* Configure downstream component, all functions */
273 list_for_each_entry(child, &linkbus->devices, bus_list) {
274 pcie_capability_read_word(child, PCI_EXP_LNKCTL, ®16);
275 child_reg[PCI_FUNC(child->devfn)] = reg16;
277 reg16 |= PCI_EXP_LNKCTL_CCC;
279 reg16 &= ~PCI_EXP_LNKCTL_CCC;
280 pcie_capability_write_word(child, PCI_EXP_LNKCTL, reg16);
283 /* Configure upstream component */
284 pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16);
287 reg16 |= PCI_EXP_LNKCTL_CCC;
289 reg16 &= ~PCI_EXP_LNKCTL_CCC;
290 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
292 if (pcie_retrain_link(link))
295 /* Training failed. Restore common clock configurations */
296 pci_err(parent, "ASPM: Could not configure common clock\n");
297 list_for_each_entry(child, &linkbus->devices, bus_list)
298 pcie_capability_write_word(child, PCI_EXP_LNKCTL,
299 child_reg[PCI_FUNC(child->devfn)]);
300 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, parent_reg);
303 /* Convert L0s latency encoding to ns */
304 static u32 calc_l0s_latency(u32 lnkcap)
306 u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L0SEL) >> 12;
309 return (5 * 1000); /* > 4us */
310 return (64 << encoding);
313 /* Convert L0s acceptable latency encoding to ns */
314 static u32 calc_l0s_acceptable(u32 encoding)
318 return (64 << encoding);
321 /* Convert L1 latency encoding to ns */
322 static u32 calc_l1_latency(u32 lnkcap)
324 u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L1EL) >> 15;
327 return (65 * 1000); /* > 64us */
328 return (1000 << encoding);
331 /* Convert L1 acceptable latency encoding to ns */
332 static u32 calc_l1_acceptable(u32 encoding)
336 return (1000 << encoding);
339 /* Convert L1SS T_pwr encoding to usec */
340 static u32 calc_l1ss_pwron(struct pci_dev *pdev, u32 scale, u32 val)
350 pci_err(pdev, "%s: Invalid T_PwrOn scale: %u\n", __func__, scale);
355 * Encode an LTR_L1.2_THRESHOLD value for the L1 PM Substates Control 1
356 * register. Ports enter L1.2 when the most recent LTR value is greater
357 * than or equal to LTR_L1.2_THRESHOLD, so we round up to make sure we
358 * don't enter L1.2 too aggressively.
360 * See PCIe r6.0, sec 5.5.1, 6.18, 7.8.3.3.
362 static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
364 u64 threshold_ns = (u64) threshold_us * 1000;
367 * LTR_L1.2_THRESHOLD_Value ("value") is a 10-bit field with max
370 if (threshold_ns <= 0x3ff * 1) {
371 *scale = 0; /* Value times 1ns */
372 *value = threshold_ns;
373 } else if (threshold_ns <= 0x3ff * 32) {
374 *scale = 1; /* Value times 32ns */
375 *value = roundup(threshold_ns, 32) / 32;
376 } else if (threshold_ns <= 0x3ff * 1024) {
377 *scale = 2; /* Value times 1024ns */
378 *value = roundup(threshold_ns, 1024) / 1024;
379 } else if (threshold_ns <= 0x3ff * 32768) {
380 *scale = 3; /* Value times 32768ns */
381 *value = roundup(threshold_ns, 32768) / 32768;
382 } else if (threshold_ns <= 0x3ff * 1048576) {
383 *scale = 4; /* Value times 1048576ns */
384 *value = roundup(threshold_ns, 1048576) / 1048576;
385 } else if (threshold_ns <= 0x3ff * (u64) 33554432) {
386 *scale = 5; /* Value times 33554432ns */
387 *value = roundup(threshold_ns, 33554432) / 33554432;
390 *value = 0x3ff; /* Max representable value */
394 static void pcie_aspm_check_latency(struct pci_dev *endpoint)
396 u32 latency, encoding, lnkcap_up, lnkcap_dw;
397 u32 l1_switch_latency = 0, latency_up_l0s;
398 u32 latency_up_l1, latency_dw_l0s, latency_dw_l1;
399 u32 acceptable_l0s, acceptable_l1;
400 struct pcie_link_state *link;
402 /* Device not in D0 doesn't need latency check */
403 if ((endpoint->current_state != PCI_D0) &&
404 (endpoint->current_state != PCI_UNKNOWN))
407 link = endpoint->bus->self->link_state;
409 /* Calculate endpoint L0s acceptable latency */
410 encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L0S) >> 6;
411 acceptable_l0s = calc_l0s_acceptable(encoding);
413 /* Calculate endpoint L1 acceptable latency */
414 encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L1) >> 9;
415 acceptable_l1 = calc_l1_acceptable(encoding);
418 struct pci_dev *dev = pci_function_0(link->pdev->subordinate);
420 /* Read direction exit latencies */
421 pcie_capability_read_dword(link->pdev, PCI_EXP_LNKCAP,
423 pcie_capability_read_dword(dev, PCI_EXP_LNKCAP,
425 latency_up_l0s = calc_l0s_latency(lnkcap_up);
426 latency_up_l1 = calc_l1_latency(lnkcap_up);
427 latency_dw_l0s = calc_l0s_latency(lnkcap_dw);
428 latency_dw_l1 = calc_l1_latency(lnkcap_dw);
430 /* Check upstream direction L0s latency */
431 if ((link->aspm_capable & ASPM_STATE_L0S_UP) &&
432 (latency_up_l0s > acceptable_l0s))
433 link->aspm_capable &= ~ASPM_STATE_L0S_UP;
435 /* Check downstream direction L0s latency */
436 if ((link->aspm_capable & ASPM_STATE_L0S_DW) &&
437 (latency_dw_l0s > acceptable_l0s))
438 link->aspm_capable &= ~ASPM_STATE_L0S_DW;
441 * Every switch on the path to root complex need 1
442 * more microsecond for L1. Spec doesn't mention L0s.
444 * The exit latencies for L1 substates are not advertised
445 * by a device. Since the spec also doesn't mention a way
446 * to determine max latencies introduced by enabling L1
447 * substates on the components, it is not clear how to do
448 * a L1 substate exit latency check. We assume that the
449 * L1 exit latencies advertised by a device include L1
450 * substate latencies (and hence do not do any check).
452 latency = max_t(u32, latency_up_l1, latency_dw_l1);
453 if ((link->aspm_capable & ASPM_STATE_L1) &&
454 (latency + l1_switch_latency > acceptable_l1))
455 link->aspm_capable &= ~ASPM_STATE_L1;
456 l1_switch_latency += 1000;
462 static void pci_clear_and_set_dword(struct pci_dev *pdev, int pos,
467 pci_read_config_dword(pdev, pos, &val);
470 pci_write_config_dword(pdev, pos, val);
473 /* Calculate L1.2 PM substate timing parameters */
474 static void aspm_calc_l1ss_info(struct pcie_link_state *link,
475 u32 parent_l1ss_cap, u32 child_l1ss_cap)
477 struct pci_dev *child = link->downstream, *parent = link->pdev;
478 u32 val1, val2, scale1, scale2;
479 u32 t_common_mode, t_power_on, l1_2_threshold, scale, value;
480 u32 ctl1 = 0, ctl2 = 0;
481 u32 pctl1, pctl2, cctl1, cctl2;
482 u32 pl1_2_enables, cl1_2_enables;
484 if (!(link->aspm_support & ASPM_STATE_L1_2_MASK))
487 /* Choose the greater of the two Port Common_Mode_Restore_Times */
488 val1 = (parent_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
489 val2 = (child_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
490 t_common_mode = max(val1, val2);
492 /* Choose the greater of the two Port T_POWER_ON times */
493 val1 = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
494 scale1 = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
495 val2 = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
496 scale2 = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
498 if (calc_l1ss_pwron(parent, scale1, val1) >
499 calc_l1ss_pwron(child, scale2, val2)) {
500 ctl2 |= scale1 | (val1 << 3);
501 t_power_on = calc_l1ss_pwron(parent, scale1, val1);
503 ctl2 |= scale2 | (val2 << 3);
504 t_power_on = calc_l1ss_pwron(child, scale2, val2);
508 * Set LTR_L1.2_THRESHOLD to the time required to transition the
509 * Link from L0 to L1.2 and back to L0 so we enter L1.2 only if
510 * downstream devices report (via LTR) that they can tolerate at
511 * least that much latency.
513 * Based on PCIe r3.1, sec 5.5.3.3.1, Figures 5-16 and 5-17, and
514 * Table 5-11. T(POWER_OFF) is at most 2us and T(L1.2) is at
517 l1_2_threshold = 2 + 4 + t_common_mode + t_power_on;
518 encode_l12_threshold(l1_2_threshold, &scale, &value);
519 ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
521 /* Some broken devices only support dword access to L1 SS */
522 pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1, &pctl1);
523 pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, &pctl2);
524 pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL1, &cctl1);
525 pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL2, &cctl2);
527 if (ctl1 == pctl1 && ctl1 == cctl1 &&
528 ctl2 == pctl2 && ctl2 == cctl2)
531 /* Disable L1.2 while updating. See PCIe r5.0, sec 5.5.4, 7.8.3.3 */
532 pl1_2_enables = pctl1 & PCI_L1SS_CTL1_L1_2_MASK;
533 cl1_2_enables = cctl1 & PCI_L1SS_CTL1_L1_2_MASK;
535 if (pl1_2_enables || cl1_2_enables) {
536 pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
537 PCI_L1SS_CTL1_L1_2_MASK, 0);
538 pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
539 PCI_L1SS_CTL1_L1_2_MASK, 0);
542 /* Program T_POWER_ON times in both ports */
543 pci_write_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, ctl2);
544 pci_write_config_dword(child, child->l1ss + PCI_L1SS_CTL2, ctl2);
546 /* Program Common_Mode_Restore_Time in upstream device */
547 pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
548 PCI_L1SS_CTL1_CM_RESTORE_TIME, ctl1);
550 /* Program LTR_L1.2_THRESHOLD time in both ports */
551 pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
552 PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
553 PCI_L1SS_CTL1_LTR_L12_TH_SCALE, ctl1);
554 pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
555 PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
556 PCI_L1SS_CTL1_LTR_L12_TH_SCALE, ctl1);
558 if (pl1_2_enables || cl1_2_enables) {
559 pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1, 0,
561 pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1, 0,
566 static void aspm_l1ss_init(struct pcie_link_state *link)
568 struct pci_dev *child = link->downstream, *parent = link->pdev;
569 u32 parent_l1ss_cap, child_l1ss_cap;
570 u32 parent_l1ss_ctl1 = 0, child_l1ss_ctl1 = 0;
572 if (!parent->l1ss || !child->l1ss)
575 /* Setup L1 substate */
576 pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CAP,
578 pci_read_config_dword(child, child->l1ss + PCI_L1SS_CAP,
581 if (!(parent_l1ss_cap & PCI_L1SS_CAP_L1_PM_SS))
583 if (!(child_l1ss_cap & PCI_L1SS_CAP_L1_PM_SS))
587 * If we don't have LTR for the entire path from the Root Complex
588 * to this device, we can't use ASPM L1.2 because it relies on the
589 * LTR_L1.2_THRESHOLD. See PCIe r4.0, secs 5.5.4, 6.18.
591 if (!child->ltr_path)
592 child_l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
594 if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_ASPM_L1_1)
595 link->aspm_support |= ASPM_STATE_L1_1;
596 if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_ASPM_L1_2)
597 link->aspm_support |= ASPM_STATE_L1_2;
598 if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_1)
599 link->aspm_support |= ASPM_STATE_L1_1_PCIPM;
600 if (parent_l1ss_cap & child_l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_2)
601 link->aspm_support |= ASPM_STATE_L1_2_PCIPM;
604 pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
607 pci_read_config_dword(child, child->l1ss + PCI_L1SS_CTL1,
610 if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
611 link->aspm_enabled |= ASPM_STATE_L1_1;
612 if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
613 link->aspm_enabled |= ASPM_STATE_L1_2;
614 if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
615 link->aspm_enabled |= ASPM_STATE_L1_1_PCIPM;
616 if (parent_l1ss_ctl1 & child_l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
617 link->aspm_enabled |= ASPM_STATE_L1_2_PCIPM;
619 if (link->aspm_support & ASPM_STATE_L1SS)
620 aspm_calc_l1ss_info(link, parent_l1ss_cap, child_l1ss_cap);
623 static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
625 struct pci_dev *child = link->downstream, *parent = link->pdev;
626 u32 parent_lnkcap, child_lnkcap;
627 u16 parent_lnkctl, child_lnkctl;
628 struct pci_bus *linkbus = parent->subordinate;
631 /* Set enabled/disable so that we will disable ASPM later */
632 link->aspm_enabled = ASPM_STATE_ALL;
633 link->aspm_disable = ASPM_STATE_ALL;
638 * If ASPM not supported, don't mess with the clocks and link,
641 pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
642 pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
643 if (!(parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPMS))
646 /* Configure common clock before checking latencies */
647 pcie_aspm_configure_common_clock(link);
650 * Re-read upstream/downstream components' register state after
651 * clock configuration. L0s & L1 exit latencies in the otherwise
652 * read-only Link Capabilities may change depending on common clock
653 * configuration (PCIe r5.0, sec 7.5.3.6).
655 pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &parent_lnkcap);
656 pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &child_lnkcap);
657 pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &parent_lnkctl);
658 pcie_capability_read_word(child, PCI_EXP_LNKCTL, &child_lnkctl);
663 * Note that we must not enable L0s in either direction on a
664 * given link unless components on both sides of the link each
667 if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L0S)
668 link->aspm_support |= ASPM_STATE_L0S;
670 if (child_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
671 link->aspm_enabled |= ASPM_STATE_L0S_UP;
672 if (parent_lnkctl & PCI_EXP_LNKCTL_ASPM_L0S)
673 link->aspm_enabled |= ASPM_STATE_L0S_DW;
676 if (parent_lnkcap & child_lnkcap & PCI_EXP_LNKCAP_ASPM_L1)
677 link->aspm_support |= ASPM_STATE_L1;
679 if (parent_lnkctl & child_lnkctl & PCI_EXP_LNKCTL_ASPM_L1)
680 link->aspm_enabled |= ASPM_STATE_L1;
682 aspm_l1ss_init(link);
684 /* Save default state */
685 link->aspm_default = link->aspm_enabled;
687 /* Setup initial capable state. Will be updated later */
688 link->aspm_capable = link->aspm_support;
690 /* Get and check endpoint acceptable latencies */
691 list_for_each_entry(child, &linkbus->devices, bus_list) {
692 if (pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT &&
693 pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END)
696 pcie_aspm_check_latency(child);
700 /* Configure the ASPM L1 substates */
701 static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
704 struct pci_dev *child = link->downstream, *parent = link->pdev;
706 enable_req = (link->aspm_enabled ^ state) & state;
709 * Here are the rules specified in the PCIe spec for enabling L1SS:
710 * - When enabling L1.x, enable bit at parent first, then at child
711 * - When disabling L1.x, disable bit at child first, then at parent
712 * - When enabling ASPM L1.x, need to disable L1
713 * (at child followed by parent).
714 * - The ASPM/PCIPM L1.2 must be disabled while programming timing
717 * To keep it simple, disable all L1SS bits first, and later enable
721 /* Disable all L1 substates */
722 pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
723 PCI_L1SS_CTL1_L1SS_MASK, 0);
724 pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
725 PCI_L1SS_CTL1_L1SS_MASK, 0);
727 * If needed, disable L1, and it gets enabled later
728 * in pcie_config_aspm_link().
730 if (enable_req & (ASPM_STATE_L1_1 | ASPM_STATE_L1_2)) {
731 pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
732 PCI_EXP_LNKCTL_ASPM_L1, 0);
733 pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
734 PCI_EXP_LNKCTL_ASPM_L1, 0);
738 if (state & ASPM_STATE_L1_1)
739 val |= PCI_L1SS_CTL1_ASPM_L1_1;
740 if (state & ASPM_STATE_L1_2)
741 val |= PCI_L1SS_CTL1_ASPM_L1_2;
742 if (state & ASPM_STATE_L1_1_PCIPM)
743 val |= PCI_L1SS_CTL1_PCIPM_L1_1;
744 if (state & ASPM_STATE_L1_2_PCIPM)
745 val |= PCI_L1SS_CTL1_PCIPM_L1_2;
747 /* Enable what we need to enable */
748 pci_clear_and_set_dword(parent, parent->l1ss + PCI_L1SS_CTL1,
749 PCI_L1SS_CTL1_L1SS_MASK, val);
750 pci_clear_and_set_dword(child, child->l1ss + PCI_L1SS_CTL1,
751 PCI_L1SS_CTL1_L1SS_MASK, val);
754 static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
756 pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
757 PCI_EXP_LNKCTL_ASPMC, val);
760 static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)
762 u32 upstream = 0, dwstream = 0;
763 struct pci_dev *child = link->downstream, *parent = link->pdev;
764 struct pci_bus *linkbus = parent->subordinate;
766 /* Enable only the states that were not explicitly disabled */
767 state &= (link->aspm_capable & ~link->aspm_disable);
769 /* Can't enable any substates if L1 is not enabled */
770 if (!(state & ASPM_STATE_L1))
771 state &= ~ASPM_STATE_L1SS;
773 /* Spec says both ports must be in D0 before enabling PCI PM substates*/
774 if (parent->current_state != PCI_D0 || child->current_state != PCI_D0) {
775 state &= ~ASPM_STATE_L1_SS_PCIPM;
776 state |= (link->aspm_enabled & ASPM_STATE_L1_SS_PCIPM);
779 /* Nothing to do if the link is already in the requested state */
780 if (link->aspm_enabled == state)
782 /* Convert ASPM state to upstream/downstream ASPM register state */
783 if (state & ASPM_STATE_L0S_UP)
784 dwstream |= PCI_EXP_LNKCTL_ASPM_L0S;
785 if (state & ASPM_STATE_L0S_DW)
786 upstream |= PCI_EXP_LNKCTL_ASPM_L0S;
787 if (state & ASPM_STATE_L1) {
788 upstream |= PCI_EXP_LNKCTL_ASPM_L1;
789 dwstream |= PCI_EXP_LNKCTL_ASPM_L1;
792 if (link->aspm_capable & ASPM_STATE_L1SS)
793 pcie_config_aspm_l1ss(link, state);
796 * Spec 2.0 suggests all functions should be configured the
797 * same setting for ASPM. Enabling ASPM L1 should be done in
798 * upstream component first and then downstream, and vice
799 * versa for disabling ASPM L1. Spec doesn't mention L0S.
801 if (state & ASPM_STATE_L1)
802 pcie_config_aspm_dev(parent, upstream);
803 list_for_each_entry(child, &linkbus->devices, bus_list)
804 pcie_config_aspm_dev(child, dwstream);
805 if (!(state & ASPM_STATE_L1))
806 pcie_config_aspm_dev(parent, upstream);
808 link->aspm_enabled = state;
811 static void pcie_config_aspm_path(struct pcie_link_state *link)
814 pcie_config_aspm_link(link, policy_to_aspm_state(link));
819 static void free_link_state(struct pcie_link_state *link)
821 link->pdev->link_state = NULL;
825 static int pcie_aspm_sanity_check(struct pci_dev *pdev)
827 struct pci_dev *child;
831 * Some functions in a slot might not all be PCIe functions,
832 * very strange. Disable ASPM for the whole slot
834 list_for_each_entry(child, &pdev->subordinate->devices, bus_list) {
835 if (!pci_is_pcie(child))
839 * If ASPM is disabled then we're not going to change
840 * the BIOS state. It's safe to continue even if it's a
848 * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
849 * RBER bit to determine if a function is 1.1 version device
851 pcie_capability_read_dword(child, PCI_EXP_DEVCAP, ®32);
852 if (!(reg32 & PCI_EXP_DEVCAP_RBER) && !aspm_force) {
853 pci_info(child, "disabling ASPM on pre-1.1 PCIe device. You can enable it with 'pcie_aspm=force'\n");
860 static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev)
862 struct pcie_link_state *link;
864 link = kzalloc(sizeof(*link), GFP_KERNEL);
868 INIT_LIST_HEAD(&link->sibling);
870 link->downstream = pci_function_0(pdev->subordinate);
873 * Root Ports and PCI/PCI-X to PCIe Bridges are roots of PCIe
874 * hierarchies. Note that some PCIe host implementations omit
875 * the root ports entirely, in which case a downstream port on
876 * a switch may become the root of the link state chain for all
877 * its subordinate endpoints.
879 if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT ||
880 pci_pcie_type(pdev) == PCI_EXP_TYPE_PCIE_BRIDGE ||
881 !pdev->bus->parent->self) {
884 struct pcie_link_state *parent;
886 parent = pdev->bus->parent->self->link_state;
892 link->parent = parent;
893 link->root = link->parent->root;
896 list_add(&link->sibling, &link_list);
897 pdev->link_state = link;
901 static void pcie_aspm_update_sysfs_visibility(struct pci_dev *pdev)
903 struct pci_dev *child;
905 list_for_each_entry(child, &pdev->subordinate->devices, bus_list)
906 sysfs_update_group(&child->dev.kobj, &aspm_ctrl_attr_group);
910 * pcie_aspm_init_link_state: Initiate PCI express link state.
911 * It is called after the pcie and its children devices are scanned.
912 * @pdev: the root port or switch downstream port
914 void pcie_aspm_init_link_state(struct pci_dev *pdev)
916 struct pcie_link_state *link;
917 int blacklist = !!pcie_aspm_sanity_check(pdev);
919 if (!aspm_support_enabled)
922 if (pdev->link_state)
926 * We allocate pcie_link_state for the component on the upstream
927 * end of a Link, so there's nothing to do unless this device is
930 if (!pcie_downstream_port(pdev))
933 /* VIA has a strange chipset, root port is under a bridge */
934 if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT &&
938 down_read(&pci_bus_sem);
939 if (list_empty(&pdev->subordinate->devices))
942 mutex_lock(&aspm_lock);
943 link = alloc_pcie_link_state(pdev);
947 * Setup initial ASPM state. Note that we need to configure
948 * upstream links also because capable state of them can be
949 * update through pcie_aspm_cap_init().
951 pcie_aspm_cap_init(link, blacklist);
953 /* Setup initial Clock PM state */
954 pcie_clkpm_cap_init(link, blacklist);
957 * At this stage drivers haven't had an opportunity to change the
958 * link policy setting. Enabling ASPM on broken hardware can cripple
959 * it even before the driver has had a chance to disable ASPM, so
960 * default to a safe level right now. If we're enabling ASPM beyond
961 * the BIOS's expectation, we'll do so once pci_enable_device() is
964 if (aspm_policy != POLICY_POWERSAVE &&
965 aspm_policy != POLICY_POWER_SUPERSAVE) {
966 pcie_config_aspm_path(link);
967 pcie_set_clkpm(link, policy_to_clkpm_state(link));
970 pcie_aspm_update_sysfs_visibility(pdev);
973 mutex_unlock(&aspm_lock);
975 up_read(&pci_bus_sem);
978 /* Recheck latencies and update aspm_capable for links under the root */
979 static void pcie_update_aspm_capable(struct pcie_link_state *root)
981 struct pcie_link_state *link;
982 BUG_ON(root->parent);
983 list_for_each_entry(link, &link_list, sibling) {
984 if (link->root != root)
986 link->aspm_capable = link->aspm_support;
988 list_for_each_entry(link, &link_list, sibling) {
989 struct pci_dev *child;
990 struct pci_bus *linkbus = link->pdev->subordinate;
991 if (link->root != root)
993 list_for_each_entry(child, &linkbus->devices, bus_list) {
994 if ((pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT) &&
995 (pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END))
997 pcie_aspm_check_latency(child);
1002 /* @pdev: the endpoint device */
1003 void pcie_aspm_exit_link_state(struct pci_dev *pdev)
1005 struct pci_dev *parent = pdev->bus->self;
1006 struct pcie_link_state *link, *root, *parent_link;
1008 if (!parent || !parent->link_state)
1011 down_read(&pci_bus_sem);
1012 mutex_lock(&aspm_lock);
1014 * All PCIe functions are in one slot, remove one function will remove
1015 * the whole slot, so just wait until we are the last function left.
1017 if (!list_empty(&parent->subordinate->devices))
1020 link = parent->link_state;
1022 parent_link = link->parent;
1024 /* All functions are removed, so just disable ASPM for the link */
1025 pcie_config_aspm_link(link, 0);
1026 list_del(&link->sibling);
1027 /* Clock PM is for endpoint device */
1028 free_link_state(link);
1030 /* Recheck latencies and configure upstream links */
1032 pcie_update_aspm_capable(root);
1033 pcie_config_aspm_path(parent_link);
1036 mutex_unlock(&aspm_lock);
1037 up_read(&pci_bus_sem);
1040 void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
1042 struct pcie_link_state *link = pdev->link_state;
1044 if (aspm_disabled || !link)
1047 if (aspm_policy != POLICY_POWERSAVE &&
1048 aspm_policy != POLICY_POWER_SUPERSAVE)
1051 down_read(&pci_bus_sem);
1052 mutex_lock(&aspm_lock);
1053 pcie_config_aspm_path(link);
1054 pcie_set_clkpm(link, policy_to_clkpm_state(link));
1055 mutex_unlock(&aspm_lock);
1056 up_read(&pci_bus_sem);
1059 static struct pcie_link_state *pcie_aspm_get_link(struct pci_dev *pdev)
1061 struct pci_dev *bridge;
1063 if (!pci_is_pcie(pdev))
1066 bridge = pci_upstream_bridge(pdev);
1067 if (!bridge || !pci_is_pcie(bridge))
1070 return bridge->link_state;
1073 static int __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
1075 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1080 * A driver requested that ASPM be disabled on this device, but
1081 * if we don't have permission to manage ASPM (e.g., on ACPI
1082 * systems we have to observe the FADT ACPI_FADT_NO_ASPM bit and
1083 * the _OSC method), we can't honor that request. Windows has
1084 * a similar mechanism using "PciASPMOptOut", which is also
1085 * ignored in this situation.
1087 if (aspm_disabled) {
1088 pci_warn(pdev, "can't disable ASPM; OS doesn't have ASPM control\n");
1093 down_read(&pci_bus_sem);
1094 mutex_lock(&aspm_lock);
1095 if (state & PCIE_LINK_STATE_L0S)
1096 link->aspm_disable |= ASPM_STATE_L0S;
1097 if (state & PCIE_LINK_STATE_L1)
1098 /* L1 PM substates require L1 */
1099 link->aspm_disable |= ASPM_STATE_L1 | ASPM_STATE_L1SS;
1100 if (state & PCIE_LINK_STATE_L1_1)
1101 link->aspm_disable |= ASPM_STATE_L1_1;
1102 if (state & PCIE_LINK_STATE_L1_2)
1103 link->aspm_disable |= ASPM_STATE_L1_2;
1104 if (state & PCIE_LINK_STATE_L1_1_PCIPM)
1105 link->aspm_disable |= ASPM_STATE_L1_1_PCIPM;
1106 if (state & PCIE_LINK_STATE_L1_2_PCIPM)
1107 link->aspm_disable |= ASPM_STATE_L1_2_PCIPM;
1108 pcie_config_aspm_link(link, policy_to_aspm_state(link));
1110 if (state & PCIE_LINK_STATE_CLKPM)
1111 link->clkpm_disable = 1;
1112 pcie_set_clkpm(link, policy_to_clkpm_state(link));
1113 mutex_unlock(&aspm_lock);
1115 up_read(&pci_bus_sem);
1120 int pci_disable_link_state_locked(struct pci_dev *pdev, int state)
1122 return __pci_disable_link_state(pdev, state, false);
1124 EXPORT_SYMBOL(pci_disable_link_state_locked);
1127 * pci_disable_link_state - Disable device's link state, so the link will
1128 * never enter specific states. Note that if the BIOS didn't grant ASPM
1129 * control to the OS, this does nothing because we can't touch the LNKCTL
1130 * register. Returns 0 or a negative errno.
1133 * @state: ASPM link state to disable
1135 int pci_disable_link_state(struct pci_dev *pdev, int state)
1137 return __pci_disable_link_state(pdev, state, true);
1139 EXPORT_SYMBOL(pci_disable_link_state);
1141 static int pcie_aspm_set_policy(const char *val,
1142 const struct kernel_param *kp)
1145 struct pcie_link_state *link;
1149 i = sysfs_match_string(policy_str, val);
1152 if (i == aspm_policy)
1155 down_read(&pci_bus_sem);
1156 mutex_lock(&aspm_lock);
1158 list_for_each_entry(link, &link_list, sibling) {
1159 pcie_config_aspm_link(link, policy_to_aspm_state(link));
1160 pcie_set_clkpm(link, policy_to_clkpm_state(link));
1162 mutex_unlock(&aspm_lock);
1163 up_read(&pci_bus_sem);
1167 static int pcie_aspm_get_policy(char *buffer, const struct kernel_param *kp)
1170 for (i = 0; i < ARRAY_SIZE(policy_str); i++)
1171 if (i == aspm_policy)
1172 cnt += sprintf(buffer + cnt, "[%s] ", policy_str[i]);
1174 cnt += sprintf(buffer + cnt, "%s ", policy_str[i]);
1175 cnt += sprintf(buffer + cnt, "\n");
1179 module_param_call(policy, pcie_aspm_set_policy, pcie_aspm_get_policy,
1183 * pcie_aspm_enabled - Check if PCIe ASPM has been enabled for a device.
1184 * @pdev: Target device.
1186 * Relies on the upstream bridge's link_state being valid. The link_state
1187 * is deallocated only when the last child of the bridge (i.e., @pdev or a
1188 * sibling) is removed, and the caller should be holding a reference to
1189 * @pdev, so this should be safe.
1191 bool pcie_aspm_enabled(struct pci_dev *pdev)
1193 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1198 return link->aspm_enabled;
1200 EXPORT_SYMBOL_GPL(pcie_aspm_enabled);
1202 static ssize_t aspm_attr_show_common(struct device *dev,
1203 struct device_attribute *attr,
1204 char *buf, u8 state)
1206 struct pci_dev *pdev = to_pci_dev(dev);
1207 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1209 return sysfs_emit(buf, "%d\n", (link->aspm_enabled & state) ? 1 : 0);
1212 static ssize_t aspm_attr_store_common(struct device *dev,
1213 struct device_attribute *attr,
1214 const char *buf, size_t len, u8 state)
1216 struct pci_dev *pdev = to_pci_dev(dev);
1217 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1220 if (kstrtobool(buf, &state_enable) < 0)
1223 down_read(&pci_bus_sem);
1224 mutex_lock(&aspm_lock);
1227 link->aspm_disable &= ~state;
1228 /* need to enable L1 for substates */
1229 if (state & ASPM_STATE_L1SS)
1230 link->aspm_disable &= ~ASPM_STATE_L1;
1232 link->aspm_disable |= state;
1235 pcie_config_aspm_link(link, policy_to_aspm_state(link));
1237 mutex_unlock(&aspm_lock);
1238 up_read(&pci_bus_sem);
1243 #define ASPM_ATTR(_f, _s) \
1244 static ssize_t _f##_show(struct device *dev, \
1245 struct device_attribute *attr, char *buf) \
1246 { return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_##_s); } \
1248 static ssize_t _f##_store(struct device *dev, \
1249 struct device_attribute *attr, \
1250 const char *buf, size_t len) \
1251 { return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_##_s); }
1253 ASPM_ATTR(l0s_aspm, L0S)
1254 ASPM_ATTR(l1_aspm, L1)
1255 ASPM_ATTR(l1_1_aspm, L1_1)
1256 ASPM_ATTR(l1_2_aspm, L1_2)
1257 ASPM_ATTR(l1_1_pcipm, L1_1_PCIPM)
1258 ASPM_ATTR(l1_2_pcipm, L1_2_PCIPM)
1260 static ssize_t clkpm_show(struct device *dev,
1261 struct device_attribute *attr, char *buf)
1263 struct pci_dev *pdev = to_pci_dev(dev);
1264 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1266 return sysfs_emit(buf, "%d\n", link->clkpm_enabled);
1269 static ssize_t clkpm_store(struct device *dev,
1270 struct device_attribute *attr,
1271 const char *buf, size_t len)
1273 struct pci_dev *pdev = to_pci_dev(dev);
1274 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1277 if (kstrtobool(buf, &state_enable) < 0)
1280 down_read(&pci_bus_sem);
1281 mutex_lock(&aspm_lock);
1283 link->clkpm_disable = !state_enable;
1284 pcie_set_clkpm(link, policy_to_clkpm_state(link));
1286 mutex_unlock(&aspm_lock);
1287 up_read(&pci_bus_sem);
1292 static DEVICE_ATTR_RW(clkpm);
1293 static DEVICE_ATTR_RW(l0s_aspm);
1294 static DEVICE_ATTR_RW(l1_aspm);
1295 static DEVICE_ATTR_RW(l1_1_aspm);
1296 static DEVICE_ATTR_RW(l1_2_aspm);
1297 static DEVICE_ATTR_RW(l1_1_pcipm);
1298 static DEVICE_ATTR_RW(l1_2_pcipm);
1300 static struct attribute *aspm_ctrl_attrs[] = {
1301 &dev_attr_clkpm.attr,
1302 &dev_attr_l0s_aspm.attr,
1303 &dev_attr_l1_aspm.attr,
1304 &dev_attr_l1_1_aspm.attr,
1305 &dev_attr_l1_2_aspm.attr,
1306 &dev_attr_l1_1_pcipm.attr,
1307 &dev_attr_l1_2_pcipm.attr,
1311 static umode_t aspm_ctrl_attrs_are_visible(struct kobject *kobj,
1312 struct attribute *a, int n)
1314 struct device *dev = kobj_to_dev(kobj);
1315 struct pci_dev *pdev = to_pci_dev(dev);
1316 struct pcie_link_state *link = pcie_aspm_get_link(pdev);
1317 static const u8 aspm_state_map[] = {
1322 ASPM_STATE_L1_1_PCIPM,
1323 ASPM_STATE_L1_2_PCIPM,
1326 if (aspm_disabled || !link)
1330 return link->clkpm_capable ? a->mode : 0;
1332 return link->aspm_capable & aspm_state_map[n - 1] ? a->mode : 0;
1335 const struct attribute_group aspm_ctrl_attr_group = {
1337 .attrs = aspm_ctrl_attrs,
1338 .is_visible = aspm_ctrl_attrs_are_visible,
1341 static int __init pcie_aspm_disable(char *str)
1343 if (!strcmp(str, "off")) {
1344 aspm_policy = POLICY_DEFAULT;
1346 aspm_support_enabled = false;
1347 printk(KERN_INFO "PCIe ASPM is disabled\n");
1348 } else if (!strcmp(str, "force")) {
1350 printk(KERN_INFO "PCIe ASPM is forcibly enabled\n");
1355 __setup("pcie_aspm=", pcie_aspm_disable);
1357 void pcie_no_aspm(void)
1360 * Disabling ASPM is intended to prevent the kernel from modifying
1361 * existing hardware state, not to clear existing state. To that end:
1362 * (a) set policy to POLICY_DEFAULT in order to avoid changing state
1363 * (b) prevent userspace from changing policy
1366 aspm_policy = POLICY_DEFAULT;
1371 bool pcie_aspm_support_enabled(void)
1373 return aspm_support_enabled;