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
9void 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}
47EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);
48