1 /*
2  * Copyright (C) 2016 Imagination Technologies
3  * Author: Paul Burton <paul.burton@imgtec.com>
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License as published by the
7  * Free Software Foundation; either version 2 of the License, or (at your
8  * option) any later version.
9  */
10 
11 #include <linux/delay.h>
12 #include <linux/io.h>
13 #include <linux/module.h>
14 #include <linux/pci.h>
15 #include <linux/pm.h>
16 
17 static struct pci_dev *pm_dev;
18 static resource_size_t io_offset;
19 
20 enum piix4_pm_io_reg {
21 	PIIX4_FUNC3IO_PMSTS			= 0x00,
22 #define PIIX4_FUNC3IO_PMSTS_PWRBTN_STS		BIT(8)
23 	PIIX4_FUNC3IO_PMCNTRL			= 0x04,
24 #define PIIX4_FUNC3IO_PMCNTRL_SUS_EN		BIT(13)
25 #define PIIX4_FUNC3IO_PMCNTRL_SUS_TYP_SOFF	(0x0 << 10)
26 };
27 
28 #define PIIX4_SUSPEND_MAGIC			0x00120002
29 
30 static const int piix4_pm_io_region = PCI_BRIDGE_RESOURCES;
31 
32 static void piix4_poweroff(void)
33 {
34 	int spec_devid;
35 	u16 sts;
36 
37 	/* Ensure the power button status is clear */
38 	while (1) {
39 		sts = inw(io_offset + PIIX4_FUNC3IO_PMSTS);
40 		if (!(sts & PIIX4_FUNC3IO_PMSTS_PWRBTN_STS))
41 			break;
42 		outw(sts, io_offset + PIIX4_FUNC3IO_PMSTS);
43 	}
44 
45 	/* Enable entry to suspend */
46 	outw(PIIX4_FUNC3IO_PMCNTRL_SUS_TYP_SOFF | PIIX4_FUNC3IO_PMCNTRL_SUS_EN,
47 	     io_offset + PIIX4_FUNC3IO_PMCNTRL);
48 
49 	/* If the special cycle occurs too soon this doesn't work... */
50 	mdelay(10);
51 
52 	/*
53 	 * The PIIX4 will enter the suspend state only after seeing a special
54 	 * cycle with the correct magic data on the PCI bus. Generate that
55 	 * cycle now.
56 	 */
57 	spec_devid = PCI_DEVID(0, PCI_DEVFN(0x1f, 0x7));
58 	pci_bus_write_config_dword(pm_dev->bus, spec_devid, 0,
59 				   PIIX4_SUSPEND_MAGIC);
60 
61 	/* Give the system some time to power down, then error */
62 	mdelay(1000);
63 	pr_emerg("Unable to poweroff system\n");
64 }
65 
66 static int piix4_poweroff_probe(struct pci_dev *dev,
67 				const struct pci_device_id *id)
68 {
69 	int res;
70 
71 	if (pm_dev)
72 		return -EINVAL;
73 
74 	/* Request access to the PIIX4 PM IO registers */
75 	res = pci_request_region(dev, piix4_pm_io_region,
76 				 "PIIX4 PM IO registers");
77 	if (res) {
78 		dev_err(&dev->dev, "failed to request PM IO registers: %d\n",
79 			res);
80 		return res;
81 	}
82 
83 	pm_dev = dev;
84 	io_offset = pci_resource_start(dev, piix4_pm_io_region);
85 	pm_power_off = piix4_poweroff;
86 
87 	return 0;
88 }
89 
90 static void piix4_poweroff_remove(struct pci_dev *dev)
91 {
92 	if (pm_power_off == piix4_poweroff)
93 		pm_power_off = NULL;
94 
95 	pci_release_region(dev, piix4_pm_io_region);
96 	pm_dev = NULL;
97 }
98 
99 static const struct pci_device_id piix4_poweroff_ids[] = {
100 	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3) },
101 	{ 0 },
102 };
103 
104 static struct pci_driver piix4_poweroff_driver = {
105 	.name		= "piix4-poweroff",
106 	.id_table	= piix4_poweroff_ids,
107 	.probe		= piix4_poweroff_probe,
108 	.remove		= piix4_poweroff_remove,
109 };
110 
111 module_pci_driver(piix4_poweroff_driver);
112 MODULE_AUTHOR("Paul Burton <paul.burton@imgtec.com>");
113 MODULE_LICENSE("GPL");
114