1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2016 Imagination Technologies
4 * Author: Paul Burton <paul.burton@mips.com>
5 */
6
7#include <linux/delay.h>
8#include <linux/io.h>
9#include <linux/module.h>
10#include <linux/pci.h>
11#include <linux/pm.h>
12
13static struct pci_dev *pm_dev;
14static resource_size_t io_offset;
15
16enum piix4_pm_io_reg {
17	PIIX4_FUNC3IO_PMSTS			= 0x00,
18#define PIIX4_FUNC3IO_PMSTS_PWRBTN_STS		BIT(8)
19	PIIX4_FUNC3IO_PMCNTRL			= 0x04,
20#define PIIX4_FUNC3IO_PMCNTRL_SUS_EN		BIT(13)
21#define PIIX4_FUNC3IO_PMCNTRL_SUS_TYP_SOFF	(0x0 << 10)
22};
23
24#define PIIX4_SUSPEND_MAGIC			0x00120002
25
26static const int piix4_pm_io_region = PCI_BRIDGE_RESOURCES;
27
28static void piix4_poweroff(void)
29{
30	int spec_devid;
31	u16 sts;
32
33	/* Ensure the power button status is clear */
34	while (1) {
35		sts = inw(io_offset + PIIX4_FUNC3IO_PMSTS);
36		if (!(sts & PIIX4_FUNC3IO_PMSTS_PWRBTN_STS))
37			break;
38		outw(sts, io_offset + PIIX4_FUNC3IO_PMSTS);
39	}
40
41	/* Enable entry to suspend */
42	outw(PIIX4_FUNC3IO_PMCNTRL_SUS_TYP_SOFF | PIIX4_FUNC3IO_PMCNTRL_SUS_EN,
43	     io_offset + PIIX4_FUNC3IO_PMCNTRL);
44
45	/* If the special cycle occurs too soon this doesn't work... */
46	mdelay(10);
47
48	/*
49	 * The PIIX4 will enter the suspend state only after seeing a special
50	 * cycle with the correct magic data on the PCI bus. Generate that
51	 * cycle now.
52	 */
53	spec_devid = PCI_DEVID(0, PCI_DEVFN(0x1f, 0x7));
54	pci_bus_write_config_dword(pm_dev->bus, spec_devid, 0,
55				   PIIX4_SUSPEND_MAGIC);
56
57	/* Give the system some time to power down, then error */
58	mdelay(1000);
59	pr_emerg("Unable to poweroff system\n");
60}
61
62static int piix4_poweroff_probe(struct pci_dev *dev,
63				const struct pci_device_id *id)
64{
65	int res;
66
67	if (pm_dev)
68		return -EINVAL;
69
70	/* Request access to the PIIX4 PM IO registers */
71	res = pci_request_region(dev, piix4_pm_io_region,
72				 "PIIX4 PM IO registers");
73	if (res) {
74		dev_err(&dev->dev, "failed to request PM IO registers: %d\n",
75			res);
76		return res;
77	}
78
79	pm_dev = dev;
80	io_offset = pci_resource_start(dev, piix4_pm_io_region);
81	pm_power_off = piix4_poweroff;
82
83	return 0;
84}
85
86static void piix4_poweroff_remove(struct pci_dev *dev)
87{
88	if (pm_power_off == piix4_poweroff)
89		pm_power_off = NULL;
90
91	pci_release_region(dev, piix4_pm_io_region);
92	pm_dev = NULL;
93}
94
95static const struct pci_device_id piix4_poweroff_ids[] = {
96	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3) },
97	{ 0 },
98};
99
100static struct pci_driver piix4_poweroff_driver = {
101	.name		= "piix4-poweroff",
102	.id_table	= piix4_poweroff_ids,
103	.probe		= piix4_poweroff_probe,
104	.remove		= piix4_poweroff_remove,
105};
106
107module_pci_driver(piix4_poweroff_driver);
108MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
109MODULE_LICENSE("GPL");
110