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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iris.c (3218B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Eurobraille/Iris power off support.
      4 *
      5 * Eurobraille's Iris machine is a PC with no APM or ACPI support.
      6 * It is shutdown by a special I/O sequence which this module provides.
      7 *
      8 *  Copyright (C) Shérab <Sebastien.Hinderer@ens-lyon.org>
      9 */
     10
     11#include <linux/moduleparam.h>
     12#include <linux/module.h>
     13#include <linux/platform_device.h>
     14#include <linux/kernel.h>
     15#include <linux/errno.h>
     16#include <linux/delay.h>
     17#include <linux/pm.h>
     18#include <asm/io.h>
     19
     20#define IRIS_GIO_BASE		0x340
     21#define IRIS_GIO_INPUT		IRIS_GIO_BASE
     22#define IRIS_GIO_OUTPUT		(IRIS_GIO_BASE + 1)
     23#define IRIS_GIO_PULSE		0x80 /* First byte to send */
     24#define IRIS_GIO_REST		0x00 /* Second byte to send */
     25#define IRIS_GIO_NODEV		0xff /* Likely not an Iris */
     26
     27MODULE_LICENSE("GPL");
     28MODULE_AUTHOR("Sébastien Hinderer <Sebastien.Hinderer@ens-lyon.org>");
     29MODULE_DESCRIPTION("A power_off handler for Iris devices from EuroBraille");
     30
     31static bool force;
     32
     33module_param(force, bool, 0);
     34MODULE_PARM_DESC(force, "Set to one to force poweroff handler installation.");
     35
     36static void (*old_pm_power_off)(void);
     37
     38static void iris_power_off(void)
     39{
     40	outb(IRIS_GIO_PULSE, IRIS_GIO_OUTPUT);
     41	msleep(850);
     42	outb(IRIS_GIO_REST, IRIS_GIO_OUTPUT);
     43}
     44
     45/*
     46 * Before installing the power_off handler, try to make sure the OS is
     47 * running on an Iris.  Since Iris does not support DMI, this is done
     48 * by reading its input port and seeing whether the read value is
     49 * meaningful.
     50 */
     51static int iris_probe(struct platform_device *pdev)
     52{
     53	unsigned char status = inb(IRIS_GIO_INPUT);
     54	if (status == IRIS_GIO_NODEV) {
     55		printk(KERN_ERR "This machine does not seem to be an Iris. "
     56			"Power off handler not installed.\n");
     57		return -ENODEV;
     58	}
     59	old_pm_power_off = pm_power_off;
     60	pm_power_off = &iris_power_off;
     61	printk(KERN_INFO "Iris power_off handler installed.\n");
     62	return 0;
     63}
     64
     65static int iris_remove(struct platform_device *pdev)
     66{
     67	pm_power_off = old_pm_power_off;
     68	printk(KERN_INFO "Iris power_off handler uninstalled.\n");
     69	return 0;
     70}
     71
     72static struct platform_driver iris_driver = {
     73	.driver		= {
     74		.name   = "iris",
     75	},
     76	.probe          = iris_probe,
     77	.remove         = iris_remove,
     78};
     79
     80static struct resource iris_resources[] = {
     81	{
     82		.start  = IRIS_GIO_BASE,
     83		.end    = IRIS_GIO_OUTPUT,
     84		.flags  = IORESOURCE_IO,
     85		.name   = "address"
     86	}
     87};
     88
     89static struct platform_device *iris_device;
     90
     91static int iris_init(void)
     92{
     93	int ret;
     94	if (force != 1) {
     95		printk(KERN_ERR "The force parameter has not been set to 1."
     96			" The Iris poweroff handler will not be installed.\n");
     97		return -ENODEV;
     98	}
     99	ret = platform_driver_register(&iris_driver);
    100	if (ret < 0) {
    101		printk(KERN_ERR "Failed to register iris platform driver: %d\n",
    102			ret);
    103		return ret;
    104	}
    105	iris_device = platform_device_register_simple("iris", (-1),
    106				iris_resources, ARRAY_SIZE(iris_resources));
    107	if (IS_ERR(iris_device)) {
    108		printk(KERN_ERR "Failed to register iris platform device\n");
    109		platform_driver_unregister(&iris_driver);
    110		return PTR_ERR(iris_device);
    111	}
    112	return 0;
    113}
    114
    115static void iris_exit(void)
    116{
    117	platform_device_unregister(iris_device);
    118	platform_driver_unregister(&iris_driver);
    119}
    120
    121module_init(iris_init);
    122module_exit(iris_exit);