cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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piix4-poweroff.c (2708B)

      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");