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  
13  static struct pci_dev *pm_dev;
14  static resource_size_t io_offset;
15  
16  enum 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  
26  static const int piix4_pm_io_region = PCI_BRIDGE_RESOURCES;
27  
piix4_poweroff(void)28  static 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  
piix4_poweroff_probe(struct pci_dev * dev,const struct pci_device_id * id)62  static 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  
piix4_poweroff_remove(struct pci_dev * dev)86  static 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  
95  static 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  
100  static 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  
107  module_pci_driver(piix4_poweroff_driver);
108  MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
109  MODULE_DESCRIPTION("Intel PIIX4 power-off driver");
110  MODULE_LICENSE("GPL");
111