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/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/pci.h>
14 #include <linux/pci_regs.h>
15 #include <linux/errno.h>
17 #include <linux/init.h>
18 #include <linux/slab.h>
19 #include <linux/jiffies.h>
20 #include <linux/delay.h>
21 #include <linux/pci-aspm.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 | \
46 u32 l0s; /* L0s latency (nsec) */
47 u32 l1; /* L1 latency (nsec) */
50 struct pcie_link_state {
51 struct pci_dev *pdev; /* Upstream component of the Link */
52 struct pci_dev *downstream; /* Downstream component, function 0 */
53 struct pcie_link_state *root; /* pointer to the root port link */
54 struct pcie_link_state *parent; /* pointer to the parent Link state */
55 struct list_head sibling; /* node in link_list */
56 struct list_head children; /* list of child link states */
57 struct list_head link; /* node in parent's children list */
60 u32 aspm_support:7; /* Supported ASPM state */
61 u32 aspm_enabled:7; /* Enabled ASPM state */
62 u32 aspm_capable:7; /* Capable ASPM state with latency */
63 u32 aspm_default:7; /* Default ASPM state by BIOS */
64 u32 aspm_disable:7; /* Disabled ASPM state */
67 u32 clkpm_capable:1; /* Clock PM capable? */
68 u32 clkpm_enabled:1; /* Current Clock PM state */
69 u32 clkpm_default:1; /* Default Clock PM state by BIOS */
72 struct aspm_latency latency_up; /* Upstream direction exit latency */
73 struct aspm_latency latency_dw; /* Downstream direction exit latency */
75 * Endpoint acceptable latencies. A pcie downstream port only
76 * has one slot under it, so at most there are 8 functions.
78 struct aspm_latency acceptable[8];
80 /* L1 PM Substate info */
82 u32 up_cap_ptr; /* L1SS cap ptr in upstream dev */
83 u32 dw_cap_ptr; /* L1SS cap ptr in downstream dev */
84 u32 ctl1; /* value to be programmed in ctl1 */
85 u32 ctl2; /* value to be programmed in ctl2 */
89 static int aspm_disabled, aspm_force;
90 static bool aspm_support_enabled = true;
91 static DEFINE_MUTEX(aspm_lock);
92 static LIST_HEAD(link_list);
94 #define POLICY_DEFAULT 0 /* BIOS default setting */
95 #define POLICY_PERFORMANCE 1 /* high performance */
96 #define POLICY_POWERSAVE 2 /* high power saving */
97 #define POLICY_POWER_SUPERSAVE 3 /* possibly even more power saving */
99 #ifdef CONFIG_PCIEASPM_PERFORMANCE
100 static int aspm_policy = POLICY_PERFORMANCE;
101 #elif defined CONFIG_PCIEASPM_POWERSAVE
102 static int aspm_policy = POLICY_POWERSAVE;
103 #elif defined CONFIG_PCIEASPM_POWER_SUPERSAVE
104 static int aspm_policy = POLICY_POWER_SUPERSAVE;
106 static int aspm_policy;
109 static const char *policy_str[] = {
110 [POLICY_DEFAULT] = "default",
111 [POLICY_PERFORMANCE] = "performance",
112 [POLICY_POWERSAVE] = "powersave",
113 [POLICY_POWER_SUPERSAVE] = "powersupersave"
116 #define LINK_RETRAIN_TIMEOUT HZ
118 static int policy_to_aspm_state(struct pcie_link_state *link)
120 switch (aspm_policy) {
121 case POLICY_PERFORMANCE:
122 /* Disable ASPM and Clock PM */
124 case POLICY_POWERSAVE:
125 /* Enable ASPM L0s/L1 */
126 return (ASPM_STATE_L0S | ASPM_STATE_L1);
127 case POLICY_POWER_SUPERSAVE:
128 /* Enable Everything */
129 return ASPM_STATE_ALL;
131 return link->aspm_default;
136 static int policy_to_clkpm_state(struct pcie_link_state *link)
138 switch (aspm_policy) {
139 case POLICY_PERFORMANCE:
140 /* Disable ASPM and Clock PM */
142 case POLICY_POWERSAVE:
143 case POLICY_POWER_SUPERSAVE:
144 /* Enable Clock PM */
147 return link->clkpm_default;
152 static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
154 struct pci_dev *child;
155 struct pci_bus *linkbus = link->pdev->subordinate;
156 u32 val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
158 list_for_each_entry(child, &linkbus->devices, bus_list)
159 pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
160 PCI_EXP_LNKCTL_CLKREQ_EN,
162 link->clkpm_enabled = !!enable;
165 static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
167 /* Don't enable Clock PM if the link is not Clock PM capable */
168 if (!link->clkpm_capable)
170 /* Need nothing if the specified equals to current state */
171 if (link->clkpm_enabled == enable)
173 pcie_set_clkpm_nocheck(link, enable);
176 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
178 int capable = 1, enabled = 1;
181 struct pci_dev *child;
182 struct pci_bus *linkbus = link->pdev->subordinate;
184 /* All functions should have the same cap and state, take the worst */
185 list_for_each_entry(child, &linkbus->devices, bus_list) {
186 pcie_capability_read_dword(child, PCI_EXP_LNKCAP, ®32);
187 if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
192 pcie_capability_read_word(child, PCI_EXP_LNKCTL, ®16);
193 if (!(reg16 & PCI_EXP_LNKCTL_CLKREQ_EN))
196 link->clkpm_enabled = enabled;
197 link->clkpm_default = enabled;
198 link->clkpm_capable = (blacklist) ? 0 : capable;
202 * pcie_aspm_configure_common_clock: check if the 2 ends of a link
203 * could use common clock. If they are, configure them to use the
204 * common clock. That will reduce the ASPM state exit latency.
206 static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
209 u16 reg16, parent_reg, child_reg[8];
210 unsigned long start_jiffies;
211 struct pci_dev *child, *parent = link->pdev;
212 struct pci_bus *linkbus = parent->subordinate;
214 * All functions of a slot should have the same Slot Clock
215 * Configuration, so just check one function
217 child = list_entry(linkbus->devices.next, struct pci_dev, bus_list);
218 BUG_ON(!pci_is_pcie(child));
220 /* Check downstream component if bit Slot Clock Configuration is 1 */
221 pcie_capability_read_word(child, PCI_EXP_LNKSTA, ®16);
222 if (!(reg16 & PCI_EXP_LNKSTA_SLC))
225 /* Check upstream component if bit Slot Clock Configuration is 1 */
226 pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16);
227 if (!(reg16 & PCI_EXP_LNKSTA_SLC))
230 /* Port might be already in common clock mode */
231 pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16);
232 if (same_clock && (reg16 & PCI_EXP_LNKCTL_CCC)) {
233 bool consistent = true;
235 list_for_each_entry(child, &linkbus->devices, bus_list) {
236 pcie_capability_read_word(child, PCI_EXP_LNKCTL,
238 if (!(reg16 & PCI_EXP_LNKCTL_CCC)) {
245 pci_warn(parent, "ASPM: current common clock configuration is broken, reconfiguring\n");
248 /* Configure downstream component, all functions */
249 list_for_each_entry(child, &linkbus->devices, bus_list) {
250 pcie_capability_read_word(child, PCI_EXP_LNKCTL, ®16);
251 child_reg[PCI_FUNC(child->devfn)] = reg16;
253 reg16 |= PCI_EXP_LNKCTL_CCC;
255 reg16 &= ~PCI_EXP_LNKCTL_CCC;
256 pcie_capability_write_word(child, PCI_EXP_LNKCTL, reg16);
259 /* Configure upstream component */
260 pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16);
263 reg16 |= PCI_EXP_LNKCTL_CCC;
265 reg16 &= ~PCI_EXP_LNKCTL_CCC;
266 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
269 reg16 |= PCI_EXP_LNKCTL_RL;
270 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
272 /* Wait for link training end. Break out after waiting for timeout */
273 start_jiffies = jiffies;
275 pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16);
276 if (!(reg16 & PCI_EXP_LNKSTA_LT))
278 if (time_after(jiffies, start_jiffies + LINK_RETRAIN_TIMEOUT))
282 if (!(reg16 & PCI_EXP_LNKSTA_LT))
285 /* Training failed. Restore common clock configurations */
286 pci_err(parent, "ASPM: Could not configure common clock\n");
287 list_for_each_entry(child, &linkbus->devices, bus_list)
288 pcie_capability_write_word(child, PCI_EXP_LNKCTL,
289 child_reg[PCI_FUNC(child->devfn)]);
290 pcie_capability_write_word(parent, PCI_EXP_LNKCTL, parent_reg);
293 /* Convert L0s latency encoding to ns */
294 static u32 calc_l0s_latency(u32 encoding)
297 return (5 * 1000); /* > 4us */
298 return (64 << encoding);
301 /* Convert L0s acceptable latency encoding to ns */
302 static u32 calc_l0s_acceptable(u32 encoding)
306 return (64 << encoding);
309 /* Convert L1 latency encoding to ns */
310 static u32 calc_l1_latency(u32 encoding)
313 return (65 * 1000); /* > 64us */
314 return (1000 << encoding);
317 /* Convert L1 acceptable latency encoding to ns */
318 static u32 calc_l1_acceptable(u32 encoding)
322 return (1000 << encoding);
325 /* Convert L1SS T_pwr encoding to usec */
326 static u32 calc_l1ss_pwron(struct pci_dev *pdev, u32 scale, u32 val)
336 pci_err(pdev, "%s: Invalid T_PwrOn scale: %u\n", __func__, scale);
340 static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
342 u32 threshold_ns = threshold_us * 1000;
344 /* See PCIe r3.1, sec 7.33.3 and sec 6.18 */
345 if (threshold_ns < 32) {
347 *value = threshold_ns;
348 } else if (threshold_ns < 1024) {
350 *value = threshold_ns >> 5;
351 } else if (threshold_ns < 32768) {
353 *value = threshold_ns >> 10;
354 } else if (threshold_ns < 1048576) {
356 *value = threshold_ns >> 15;
357 } else if (threshold_ns < 33554432) {
359 *value = threshold_ns >> 20;
362 *value = threshold_ns >> 25;
366 struct aspm_register_info {
369 u32 latency_encoding_l0s;
370 u32 latency_encoding_l1;
379 static void pcie_get_aspm_reg(struct pci_dev *pdev,
380 struct aspm_register_info *info)
385 pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, ®32);
386 info->support = (reg32 & PCI_EXP_LNKCAP_ASPMS) >> 10;
387 info->latency_encoding_l0s = (reg32 & PCI_EXP_LNKCAP_L0SEL) >> 12;
388 info->latency_encoding_l1 = (reg32 & PCI_EXP_LNKCAP_L1EL) >> 15;
389 pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, ®16);
390 info->enabled = reg16 & PCI_EXP_LNKCTL_ASPMC;
392 /* Read L1 PM substate capabilities */
393 info->l1ss_cap = info->l1ss_ctl1 = info->l1ss_ctl2 = 0;
394 info->l1ss_cap_ptr = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_L1SS);
395 if (!info->l1ss_cap_ptr)
397 pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CAP,
399 if (!(info->l1ss_cap & PCI_L1SS_CAP_L1_PM_SS)) {
403 pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL1,
405 pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL2,
409 static void pcie_aspm_check_latency(struct pci_dev *endpoint)
411 u32 latency, l1_switch_latency = 0;
412 struct aspm_latency *acceptable;
413 struct pcie_link_state *link;
415 /* Device not in D0 doesn't need latency check */
416 if ((endpoint->current_state != PCI_D0) &&
417 (endpoint->current_state != PCI_UNKNOWN))
420 link = endpoint->bus->self->link_state;
421 acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)];
424 /* Check upstream direction L0s latency */
425 if ((link->aspm_capable & ASPM_STATE_L0S_UP) &&
426 (link->latency_up.l0s > acceptable->l0s))
427 link->aspm_capable &= ~ASPM_STATE_L0S_UP;
429 /* Check downstream direction L0s latency */
430 if ((link->aspm_capable & ASPM_STATE_L0S_DW) &&
431 (link->latency_dw.l0s > acceptable->l0s))
432 link->aspm_capable &= ~ASPM_STATE_L0S_DW;
435 * Every switch on the path to root complex need 1
436 * more microsecond for L1. Spec doesn't mention L0s.
438 * The exit latencies for L1 substates are not advertised
439 * by a device. Since the spec also doesn't mention a way
440 * to determine max latencies introduced by enabling L1
441 * substates on the components, it is not clear how to do
442 * a L1 substate exit latency check. We assume that the
443 * L1 exit latencies advertised by a device include L1
444 * substate latencies (and hence do not do any check).
446 latency = max_t(u32, link->latency_up.l1, link->latency_dw.l1);
447 if ((link->aspm_capable & ASPM_STATE_L1) &&
448 (latency + l1_switch_latency > acceptable->l1))
449 link->aspm_capable &= ~ASPM_STATE_L1;
450 l1_switch_latency += 1000;
457 * The L1 PM substate capability is only implemented in function 0 in a
458 * multi function device.
460 static struct pci_dev *pci_function_0(struct pci_bus *linkbus)
462 struct pci_dev *child;
464 list_for_each_entry(child, &linkbus->devices, bus_list)
465 if (PCI_FUNC(child->devfn) == 0)
470 /* Calculate L1.2 PM substate timing parameters */
471 static void aspm_calc_l1ss_info(struct pcie_link_state *link,
472 struct aspm_register_info *upreg,
473 struct aspm_register_info *dwreg)
475 u32 val1, val2, scale1, scale2;
476 u32 t_common_mode, t_power_on, l1_2_threshold, scale, value;
478 link->l1ss.up_cap_ptr = upreg->l1ss_cap_ptr;
479 link->l1ss.dw_cap_ptr = dwreg->l1ss_cap_ptr;
480 link->l1ss.ctl1 = link->l1ss.ctl2 = 0;
482 if (!(link->aspm_support & ASPM_STATE_L1_2_MASK))
485 /* Choose the greater of the two Port Common_Mode_Restore_Times */
486 val1 = (upreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
487 val2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
488 t_common_mode = max(val1, val2);
490 /* Choose the greater of the two Port T_POWER_ON times */
491 val1 = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
492 scale1 = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
493 val2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
494 scale2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
496 if (calc_l1ss_pwron(link->pdev, scale1, val1) >
497 calc_l1ss_pwron(link->downstream, scale2, val2)) {
498 link->l1ss.ctl2 |= scale1 | (val1 << 3);
499 t_power_on = calc_l1ss_pwron(link->pdev, scale1, val1);
501 link->l1ss.ctl2 |= scale2 | (val2 << 3);
502 t_power_on = calc_l1ss_pwron(link->downstream, scale2, val2);
506 * Set LTR_L1.2_THRESHOLD to the time required to transition the
507 * Link from L0 to L1.2 and back to L0 so we enter L1.2 only if
508 * downstream devices report (via LTR) that they can tolerate at
509 * least that much latency.
511 * Based on PCIe r3.1, sec 5.5.3.3.1, Figures 5-16 and 5-17, and
512 * Table 5-11. T(POWER_OFF) is at most 2us and T(L1.2) is at
515 l1_2_threshold = 2 + 4 + t_common_mode + t_power_on;
516 encode_l12_threshold(l1_2_threshold, &scale, &value);
517 link->l1ss.ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
520 static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
522 struct pci_dev *child = link->downstream, *parent = link->pdev;
523 struct pci_bus *linkbus = parent->subordinate;
524 struct aspm_register_info upreg, dwreg;
527 /* Set enabled/disable so that we will disable ASPM later */
528 link->aspm_enabled = ASPM_STATE_ALL;
529 link->aspm_disable = ASPM_STATE_ALL;
533 /* Get upstream/downstream components' register state */
534 pcie_get_aspm_reg(parent, &upreg);
535 pcie_get_aspm_reg(child, &dwreg);
538 * If ASPM not supported, don't mess with the clocks and link,
541 if (!(upreg.support & dwreg.support))
544 /* Configure common clock before checking latencies */
545 pcie_aspm_configure_common_clock(link);
548 * Re-read upstream/downstream components' register state
549 * after clock configuration
551 pcie_get_aspm_reg(parent, &upreg);
552 pcie_get_aspm_reg(child, &dwreg);
557 * Note that we must not enable L0s in either direction on a
558 * given link unless components on both sides of the link each
561 if (dwreg.support & upreg.support & PCIE_LINK_STATE_L0S)
562 link->aspm_support |= ASPM_STATE_L0S;
563 if (dwreg.enabled & PCIE_LINK_STATE_L0S)
564 link->aspm_enabled |= ASPM_STATE_L0S_UP;
565 if (upreg.enabled & PCIE_LINK_STATE_L0S)
566 link->aspm_enabled |= ASPM_STATE_L0S_DW;
567 link->latency_up.l0s = calc_l0s_latency(upreg.latency_encoding_l0s);
568 link->latency_dw.l0s = calc_l0s_latency(dwreg.latency_encoding_l0s);
571 if (upreg.support & dwreg.support & PCIE_LINK_STATE_L1)
572 link->aspm_support |= ASPM_STATE_L1;
573 if (upreg.enabled & dwreg.enabled & PCIE_LINK_STATE_L1)
574 link->aspm_enabled |= ASPM_STATE_L1;
575 link->latency_up.l1 = calc_l1_latency(upreg.latency_encoding_l1);
576 link->latency_dw.l1 = calc_l1_latency(dwreg.latency_encoding_l1);
578 /* Setup L1 substate */
579 if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_ASPM_L1_1)
580 link->aspm_support |= ASPM_STATE_L1_1;
581 if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_ASPM_L1_2)
582 link->aspm_support |= ASPM_STATE_L1_2;
583 if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_1)
584 link->aspm_support |= ASPM_STATE_L1_1_PCIPM;
585 if (upreg.l1ss_cap & dwreg.l1ss_cap & PCI_L1SS_CAP_PCIPM_L1_2)
586 link->aspm_support |= ASPM_STATE_L1_2_PCIPM;
588 if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_1)
589 link->aspm_enabled |= ASPM_STATE_L1_1;
590 if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_ASPM_L1_2)
591 link->aspm_enabled |= ASPM_STATE_L1_2;
592 if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_1)
593 link->aspm_enabled |= ASPM_STATE_L1_1_PCIPM;
594 if (upreg.l1ss_ctl1 & dwreg.l1ss_ctl1 & PCI_L1SS_CTL1_PCIPM_L1_2)
595 link->aspm_enabled |= ASPM_STATE_L1_2_PCIPM;
597 if (link->aspm_support & ASPM_STATE_L1SS)
598 aspm_calc_l1ss_info(link, &upreg, &dwreg);
600 /* Save default state */
601 link->aspm_default = link->aspm_enabled;
603 /* Setup initial capable state. Will be updated later */
604 link->aspm_capable = link->aspm_support;
606 * If the downstream component has pci bridge function, don't
609 list_for_each_entry(child, &linkbus->devices, bus_list) {
610 if (pci_pcie_type(child) == PCI_EXP_TYPE_PCI_BRIDGE) {
611 link->aspm_disable = ASPM_STATE_ALL;
616 /* Get and check endpoint acceptable latencies */
617 list_for_each_entry(child, &linkbus->devices, bus_list) {
619 struct aspm_latency *acceptable =
620 &link->acceptable[PCI_FUNC(child->devfn)];
622 if (pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT &&
623 pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END)
626 pcie_capability_read_dword(child, PCI_EXP_DEVCAP, ®32);
627 /* Calculate endpoint L0s acceptable latency */
628 encoding = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6;
629 acceptable->l0s = calc_l0s_acceptable(encoding);
630 /* Calculate endpoint L1 acceptable latency */
631 encoding = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
632 acceptable->l1 = calc_l1_acceptable(encoding);
634 pcie_aspm_check_latency(child);
638 static void pci_clear_and_set_dword(struct pci_dev *pdev, int pos,
643 pci_read_config_dword(pdev, pos, &val);
646 pci_write_config_dword(pdev, pos, val);
649 /* Configure the ASPM L1 substates */
650 static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
653 struct pci_dev *child = link->downstream, *parent = link->pdev;
654 u32 up_cap_ptr = link->l1ss.up_cap_ptr;
655 u32 dw_cap_ptr = link->l1ss.dw_cap_ptr;
657 enable_req = (link->aspm_enabled ^ state) & state;
660 * Here are the rules specified in the PCIe spec for enabling L1SS:
661 * - When enabling L1.x, enable bit at parent first, then at child
662 * - When disabling L1.x, disable bit at child first, then at parent
663 * - When enabling ASPM L1.x, need to disable L1
664 * (at child followed by parent).
665 * - The ASPM/PCIPM L1.2 must be disabled while programming timing
668 * To keep it simple, disable all L1SS bits first, and later enable
672 /* Disable all L1 substates */
673 pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
674 PCI_L1SS_CTL1_L1SS_MASK, 0);
675 pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
676 PCI_L1SS_CTL1_L1SS_MASK, 0);
678 * If needed, disable L1, and it gets enabled later
679 * in pcie_config_aspm_link().
681 if (enable_req & (ASPM_STATE_L1_1 | ASPM_STATE_L1_2)) {
682 pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
683 PCI_EXP_LNKCTL_ASPM_L1, 0);
684 pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
685 PCI_EXP_LNKCTL_ASPM_L1, 0);
688 if (enable_req & ASPM_STATE_L1_2_MASK) {
690 /* Program T_POWER_ON times in both ports */
691 pci_write_config_dword(parent, up_cap_ptr + PCI_L1SS_CTL2,
693 pci_write_config_dword(child, dw_cap_ptr + PCI_L1SS_CTL2,
696 /* Program Common_Mode_Restore_Time in upstream device */
697 pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
698 PCI_L1SS_CTL1_CM_RESTORE_TIME,
701 /* Program LTR_L1.2_THRESHOLD time in both ports */
702 pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
703 PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
704 PCI_L1SS_CTL1_LTR_L12_TH_SCALE,
706 pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
707 PCI_L1SS_CTL1_LTR_L12_TH_VALUE |
708 PCI_L1SS_CTL1_LTR_L12_TH_SCALE,
713 if (state & ASPM_STATE_L1_1)
714 val |= PCI_L1SS_CTL1_ASPM_L1_1;
715 if (state & ASPM_STATE_L1_2)
716 val |= PCI_L1SS_CTL1_ASPM_L1_2;
717 if (state & ASPM_STATE_L1_1_PCIPM)
718 val |= PCI_L1SS_CTL1_PCIPM_L1_1;
719 if (state & ASPM_STATE_L1_2_PCIPM)
720 val |= PCI_L1SS_CTL1_PCIPM_L1_2;
722 /* Enable what we need to enable */
723 pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
724 PCI_L1SS_CAP_L1_PM_SS, val);
725 pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
726 PCI_L1SS_CAP_L1_PM_SS, val);
729 static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
731 pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
732 PCI_EXP_LNKCTL_ASPMC, val);
735 static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)
737 u32 upstream = 0, dwstream = 0;
738 struct pci_dev *child = link->downstream, *parent = link->pdev;
739 struct pci_bus *linkbus = parent->subordinate;
741 /* Enable only the states that were not explicitly disabled */
742 state &= (link->aspm_capable & ~link->aspm_disable);
744 /* Can't enable any substates if L1 is not enabled */
745 if (!(state & ASPM_STATE_L1))
746 state &= ~ASPM_STATE_L1SS;
748 /* Spec says both ports must be in D0 before enabling PCI PM substates*/
749 if (parent->current_state != PCI_D0 || child->current_state != PCI_D0) {
750 state &= ~ASPM_STATE_L1_SS_PCIPM;
751 state |= (link->aspm_enabled & ASPM_STATE_L1_SS_PCIPM);
754 /* Nothing to do if the link is already in the requested state */
755 if (link->aspm_enabled == state)
757 /* Convert ASPM state to upstream/downstream ASPM register state */
758 if (state & ASPM_STATE_L0S_UP)
759 dwstream |= PCI_EXP_LNKCTL_ASPM_L0S;
760 if (state & ASPM_STATE_L0S_DW)
761 upstream |= PCI_EXP_LNKCTL_ASPM_L0S;
762 if (state & ASPM_STATE_L1) {
763 upstream |= PCI_EXP_LNKCTL_ASPM_L1;
764 dwstream |= PCI_EXP_LNKCTL_ASPM_L1;
767 if (link->aspm_capable & ASPM_STATE_L1SS)
768 pcie_config_aspm_l1ss(link, state);
771 * Spec 2.0 suggests all functions should be configured the
772 * same setting for ASPM. Enabling ASPM L1 should be done in
773 * upstream component first and then downstream, and vice
774 * versa for disabling ASPM L1. Spec doesn't mention L0S.
776 if (state & ASPM_STATE_L1)
777 pcie_config_aspm_dev(parent, upstream);
778 list_for_each_entry(child, &linkbus->devices, bus_list)
779 pcie_config_aspm_dev(child, dwstream);
780 if (!(state & ASPM_STATE_L1))
781 pcie_config_aspm_dev(parent, upstream);
783 link->aspm_enabled = state;
786 static void pcie_config_aspm_path(struct pcie_link_state *link)
789 pcie_config_aspm_link(link, policy_to_aspm_state(link));
794 static void free_link_state(struct pcie_link_state *link)
796 link->pdev->link_state = NULL;
800 static int pcie_aspm_sanity_check(struct pci_dev *pdev)
802 struct pci_dev *child;
806 * Some functions in a slot might not all be PCIe functions,
807 * very strange. Disable ASPM for the whole slot
809 list_for_each_entry(child, &pdev->subordinate->devices, bus_list) {
810 if (!pci_is_pcie(child))
814 * If ASPM is disabled then we're not going to change
815 * the BIOS state. It's safe to continue even if it's a
823 * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
824 * RBER bit to determine if a function is 1.1 version device
826 pcie_capability_read_dword(child, PCI_EXP_DEVCAP, ®32);
827 if (!(reg32 & PCI_EXP_DEVCAP_RBER) && !aspm_force) {
828 pci_info(child, "disabling ASPM on pre-1.1 PCIe device. You can enable it with 'pcie_aspm=force'\n");
835 static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev)
837 struct pcie_link_state *link;
839 link = kzalloc(sizeof(*link), GFP_KERNEL);
843 INIT_LIST_HEAD(&link->sibling);
844 INIT_LIST_HEAD(&link->children);
845 INIT_LIST_HEAD(&link->link);
847 link->downstream = pci_function_0(pdev->subordinate);
850 * Root Ports and PCI/PCI-X to PCIe Bridges are roots of PCIe
851 * hierarchies. Note that some PCIe host implementations omit
852 * the root ports entirely, in which case a downstream port on
853 * a switch may become the root of the link state chain for all
854 * its subordinate endpoints.
856 if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT ||
857 pci_pcie_type(pdev) == PCI_EXP_TYPE_PCIE_BRIDGE ||
858 !pdev->bus->parent->self) {
861 struct pcie_link_state *parent;
863 parent = pdev->bus->parent->self->link_state;
869 link->parent = parent;
870 link->root = link->parent->root;
871 list_add(&link->link, &parent->children);
874 list_add(&link->sibling, &link_list);
875 pdev->link_state = link;
880 * pcie_aspm_init_link_state: Initiate PCI express link state.
881 * It is called after the pcie and its children devices are scanned.
882 * @pdev: the root port or switch downstream port
884 void pcie_aspm_init_link_state(struct pci_dev *pdev)
886 struct pcie_link_state *link;
887 int blacklist = !!pcie_aspm_sanity_check(pdev);
889 if (!aspm_support_enabled)
892 if (pdev->link_state)
896 * We allocate pcie_link_state for the component on the upstream
897 * end of a Link, so there's nothing to do unless this device has a
898 * Link on its secondary side.
900 if (!pdev->has_secondary_link)
903 /* VIA has a strange chipset, root port is under a bridge */
904 if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT &&
908 down_read(&pci_bus_sem);
909 if (list_empty(&pdev->subordinate->devices))
912 mutex_lock(&aspm_lock);
913 link = alloc_pcie_link_state(pdev);
917 * Setup initial ASPM state. Note that we need to configure
918 * upstream links also because capable state of them can be
919 * update through pcie_aspm_cap_init().
921 pcie_aspm_cap_init(link, blacklist);
923 /* Setup initial Clock PM state */
924 pcie_clkpm_cap_init(link, blacklist);
927 * At this stage drivers haven't had an opportunity to change the
928 * link policy setting. Enabling ASPM on broken hardware can cripple
929 * it even before the driver has had a chance to disable ASPM, so
930 * default to a safe level right now. If we're enabling ASPM beyond
931 * the BIOS's expectation, we'll do so once pci_enable_device() is
934 if (aspm_policy != POLICY_POWERSAVE &&
935 aspm_policy != POLICY_POWER_SUPERSAVE) {
936 pcie_config_aspm_path(link);
937 pcie_set_clkpm(link, policy_to_clkpm_state(link));
941 mutex_unlock(&aspm_lock);
943 up_read(&pci_bus_sem);
946 /* Recheck latencies and update aspm_capable for links under the root */
947 static void pcie_update_aspm_capable(struct pcie_link_state *root)
949 struct pcie_link_state *link;
950 BUG_ON(root->parent);
951 list_for_each_entry(link, &link_list, sibling) {
952 if (link->root != root)
954 link->aspm_capable = link->aspm_support;
956 list_for_each_entry(link, &link_list, sibling) {
957 struct pci_dev *child;
958 struct pci_bus *linkbus = link->pdev->subordinate;
959 if (link->root != root)
961 list_for_each_entry(child, &linkbus->devices, bus_list) {
962 if ((pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT) &&
963 (pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END))
965 pcie_aspm_check_latency(child);
970 /* @pdev: the endpoint device */
971 void pcie_aspm_exit_link_state(struct pci_dev *pdev)
973 struct pci_dev *parent = pdev->bus->self;
974 struct pcie_link_state *link, *root, *parent_link;
976 if (!parent || !parent->link_state)
979 down_read(&pci_bus_sem);
980 mutex_lock(&aspm_lock);
982 * All PCIe functions are in one slot, remove one function will remove
983 * the whole slot, so just wait until we are the last function left.
985 if (!list_is_last(&pdev->bus_list, &parent->subordinate->devices))
988 link = parent->link_state;
990 parent_link = link->parent;
992 /* All functions are removed, so just disable ASPM for the link */
993 pcie_config_aspm_link(link, 0);
994 list_del(&link->sibling);
995 list_del(&link->link);
996 /* Clock PM is for endpoint device */
997 free_link_state(link);
999 /* Recheck latencies and configure upstream links */
1001 pcie_update_aspm_capable(root);
1002 pcie_config_aspm_path(parent_link);
1005 mutex_unlock(&aspm_lock);
1006 up_read(&pci_bus_sem);
1009 /* @pdev: the root port or switch downstream port */
1010 void pcie_aspm_pm_state_change(struct pci_dev *pdev)
1012 struct pcie_link_state *link = pdev->link_state;
1014 if (aspm_disabled || !link)
1017 * Devices changed PM state, we should recheck if latency
1018 * meets all functions' requirement
1020 down_read(&pci_bus_sem);
1021 mutex_lock(&aspm_lock);
1022 pcie_update_aspm_capable(link->root);
1023 pcie_config_aspm_path(link);
1024 mutex_unlock(&aspm_lock);
1025 up_read(&pci_bus_sem);
1028 void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
1030 struct pcie_link_state *link = pdev->link_state;
1032 if (aspm_disabled || !link)
1035 if (aspm_policy != POLICY_POWERSAVE &&
1036 aspm_policy != POLICY_POWER_SUPERSAVE)
1039 down_read(&pci_bus_sem);
1040 mutex_lock(&aspm_lock);
1041 pcie_config_aspm_path(link);
1042 pcie_set_clkpm(link, policy_to_clkpm_state(link));
1043 mutex_unlock(&aspm_lock);
1044 up_read(&pci_bus_sem);
1047 static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
1049 struct pci_dev *parent = pdev->bus->self;
1050 struct pcie_link_state *link;
1052 if (!pci_is_pcie(pdev))
1055 if (pdev->has_secondary_link)
1057 if (!parent || !parent->link_state)
1061 * A driver requested that ASPM be disabled on this device, but
1062 * if we don't have permission to manage ASPM (e.g., on ACPI
1063 * systems we have to observe the FADT ACPI_FADT_NO_ASPM bit and
1064 * the _OSC method), we can't honor that request. Windows has
1065 * a similar mechanism using "PciASPMOptOut", which is also
1066 * ignored in this situation.
1068 if (aspm_disabled) {
1069 pci_warn(pdev, "can't disable ASPM; OS doesn't have ASPM control\n");
1074 down_read(&pci_bus_sem);
1075 mutex_lock(&aspm_lock);
1076 link = parent->link_state;
1077 if (state & PCIE_LINK_STATE_L0S)
1078 link->aspm_disable |= ASPM_STATE_L0S;
1079 if (state & PCIE_LINK_STATE_L1)
1080 link->aspm_disable |= ASPM_STATE_L1;
1081 pcie_config_aspm_link(link, policy_to_aspm_state(link));
1083 if (state & PCIE_LINK_STATE_CLKPM) {
1084 link->clkpm_capable = 0;
1085 pcie_set_clkpm(link, 0);
1087 mutex_unlock(&aspm_lock);
1089 up_read(&pci_bus_sem);
1092 void pci_disable_link_state_locked(struct pci_dev *pdev, int state)
1094 __pci_disable_link_state(pdev, state, false);
1096 EXPORT_SYMBOL(pci_disable_link_state_locked);
1099 * pci_disable_link_state - Disable device's link state, so the link will
1100 * never enter specific states. Note that if the BIOS didn't grant ASPM
1101 * control to the OS, this does nothing because we can't touch the LNKCTL
1105 * @state: ASPM link state to disable
1107 void pci_disable_link_state(struct pci_dev *pdev, int state)
1109 __pci_disable_link_state(pdev, state, true);
1111 EXPORT_SYMBOL(pci_disable_link_state);
1113 static int pcie_aspm_set_policy(const char *val,
1114 const struct kernel_param *kp)
1117 struct pcie_link_state *link;
1121 for (i = 0; i < ARRAY_SIZE(policy_str); i++)
1122 if (!strncmp(val, policy_str[i], strlen(policy_str[i])))
1124 if (i >= ARRAY_SIZE(policy_str))
1126 if (i == aspm_policy)
1129 down_read(&pci_bus_sem);
1130 mutex_lock(&aspm_lock);
1132 list_for_each_entry(link, &link_list, sibling) {
1133 pcie_config_aspm_link(link, policy_to_aspm_state(link));
1134 pcie_set_clkpm(link, policy_to_clkpm_state(link));
1136 mutex_unlock(&aspm_lock);
1137 up_read(&pci_bus_sem);
1141 static int pcie_aspm_get_policy(char *buffer, const struct kernel_param *kp)
1144 for (i = 0; i < ARRAY_SIZE(policy_str); i++)
1145 if (i == aspm_policy)
1146 cnt += sprintf(buffer + cnt, "[%s] ", policy_str[i]);
1148 cnt += sprintf(buffer + cnt, "%s ", policy_str[i]);
1152 module_param_call(policy, pcie_aspm_set_policy, pcie_aspm_get_policy,
1155 #ifdef CONFIG_PCIEASPM_DEBUG
1156 static ssize_t link_state_show(struct device *dev,
1157 struct device_attribute *attr,
1160 struct pci_dev *pci_device = to_pci_dev(dev);
1161 struct pcie_link_state *link_state = pci_device->link_state;
1163 return sprintf(buf, "%d\n", link_state->aspm_enabled);
1166 static ssize_t link_state_store(struct device *dev,
1167 struct device_attribute *attr,
1171 struct pci_dev *pdev = to_pci_dev(dev);
1172 struct pcie_link_state *link, *root = pdev->link_state->root;
1178 if (kstrtouint(buf, 10, &state))
1180 if ((state & ~ASPM_STATE_ALL) != 0)
1183 down_read(&pci_bus_sem);
1184 mutex_lock(&aspm_lock);
1185 list_for_each_entry(link, &link_list, sibling) {
1186 if (link->root != root)
1188 pcie_config_aspm_link(link, state);
1190 mutex_unlock(&aspm_lock);
1191 up_read(&pci_bus_sem);
1195 static ssize_t clk_ctl_show(struct device *dev,
1196 struct device_attribute *attr,
1199 struct pci_dev *pci_device = to_pci_dev(dev);
1200 struct pcie_link_state *link_state = pci_device->link_state;
1202 return sprintf(buf, "%d\n", link_state->clkpm_enabled);
1205 static ssize_t clk_ctl_store(struct device *dev,
1206 struct device_attribute *attr,
1210 struct pci_dev *pdev = to_pci_dev(dev);
1213 if (strtobool(buf, &state))
1216 down_read(&pci_bus_sem);
1217 mutex_lock(&aspm_lock);
1218 pcie_set_clkpm_nocheck(pdev->link_state, state);
1219 mutex_unlock(&aspm_lock);
1220 up_read(&pci_bus_sem);
1225 static DEVICE_ATTR_RW(link_state);
1226 static DEVICE_ATTR_RW(clk_ctl);
1228 static char power_group[] = "power";
1229 void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev)
1231 struct pcie_link_state *link_state = pdev->link_state;
1236 if (link_state->aspm_support)
1237 sysfs_add_file_to_group(&pdev->dev.kobj,
1238 &dev_attr_link_state.attr, power_group);
1239 if (link_state->clkpm_capable)
1240 sysfs_add_file_to_group(&pdev->dev.kobj,
1241 &dev_attr_clk_ctl.attr, power_group);
1244 void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
1246 struct pcie_link_state *link_state = pdev->link_state;
1251 if (link_state->aspm_support)
1252 sysfs_remove_file_from_group(&pdev->dev.kobj,
1253 &dev_attr_link_state.attr, power_group);
1254 if (link_state->clkpm_capable)
1255 sysfs_remove_file_from_group(&pdev->dev.kobj,
1256 &dev_attr_clk_ctl.attr, power_group);
1260 static int __init pcie_aspm_disable(char *str)
1262 if (!strcmp(str, "off")) {
1263 aspm_policy = POLICY_DEFAULT;
1265 aspm_support_enabled = false;
1266 printk(KERN_INFO "PCIe ASPM is disabled\n");
1267 } else if (!strcmp(str, "force")) {
1269 printk(KERN_INFO "PCIe ASPM is forcibly enabled\n");
1274 __setup("pcie_aspm=", pcie_aspm_disable);
1276 void pcie_no_aspm(void)
1279 * Disabling ASPM is intended to prevent the kernel from modifying
1280 * existing hardware state, not to clear existing state. To that end:
1281 * (a) set policy to POLICY_DEFAULT in order to avoid changing state
1282 * (b) prevent userspace from changing policy
1285 aspm_policy = POLICY_DEFAULT;
1290 bool pcie_aspm_support_enabled(void)
1292 return aspm_support_enabled;
1294 EXPORT_SYMBOL(pcie_aspm_support_enabled);