drivers/power/reset/piix4-poweroff.c

   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
  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
  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
  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_LICENSE("GPL");