1 // SPDX-License-Identifier: ISC
2 /*
3 * Copyright (C) 2019 Lorenzo Bianconi <lorenzo@kernel.org>
4 */
5
6 #include "mt76.h"
7 #include <linux/pci.h>
8
mt76_pci_disable_aspm(struct pci_dev * pdev)9 void mt76_pci_disable_aspm(struct pci_dev *pdev)
10 {
11 struct pci_dev *parent = pdev->bus->self;
12 u16 aspm_conf, parent_aspm_conf = 0;
13
14 pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
15 aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
16 if (parent) {
17 pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
18 &parent_aspm_conf);
19 parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
20 }
21
22 if (!aspm_conf && (!parent || !parent_aspm_conf)) {
23 /* aspm already disabled */
24 return;
25 }
26
27 dev_info(&pdev->dev, "disabling ASPM %s %s\n",
28 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "",
29 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "");
30
31 if (IS_ENABLED(CONFIG_PCIEASPM)) {
32 int err;
33
34 err = pci_disable_link_state(pdev, aspm_conf);
35 if (!err)
36 return;
37 }
38
39 /* both device and parent should have the same ASPM setting.
40 * disable ASPM in downstream component first and then upstream.
41 */
42 pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_conf);
43 if (parent)
44 pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
45 aspm_conf);
46 }
47 EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);
48
mt76_pci_aspm_supported(struct pci_dev * pdev)49 bool mt76_pci_aspm_supported(struct pci_dev *pdev)
50 {
51 struct pci_dev *parent = pdev->bus->self;
52 u16 aspm_conf, parent_aspm_conf = 0;
53 bool result = true;
54
55 pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
56 aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
57 if (parent) {
58 pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
59 &parent_aspm_conf);
60 parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
61 }
62
63 if (!aspm_conf && (!parent || !parent_aspm_conf)) {
64 /* aspm already disabled */
65 result = false;
66 }
67
68 return result;
69 }
70 EXPORT_SYMBOL_GPL(mt76_pci_aspm_supported);
71