drivers/power/reset/piix4-poweroff.c

   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");