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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spi-slave-system-control.c (3667B)

      1/*
      2 * SPI slave handler controlling system state
      3 *
      4 * This SPI slave handler allows remote control of system reboot, power off,
      5 * halt, and suspend.
      6 *
      7 * Copyright (C) 2016-2017 Glider bvba
      8 *
      9 * This file is subject to the terms and conditions of the GNU General Public
     10 * License.  See the file "COPYING" in the main directory of this archive
     11 * for more details.
     12 *
     13 * Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote
     14 * system):
     15 *
     16 *   # reboot='\x7c\x50'
     17 *   # poweroff='\x71\x3f'
     18 *   # halt='\x38\x76'
     19 *   # suspend='\x1b\x1b'
     20 *   # spidev_test -D /dev/spidev2.0 -p $suspend # or $reboot, $poweroff, $halt
     21 */
     22
     23#include <linux/completion.h>
     24#include <linux/module.h>
     25#include <linux/reboot.h>
     26#include <linux/suspend.h>
     27#include <linux/spi/spi.h>
     28
     29/*
     30 * The numbers are chosen to display something human-readable on two 7-segment
     31 * displays connected to two 74HC595 shift registers
     32 */
     33#define CMD_REBOOT	0x7c50	/* rb */
     34#define CMD_POWEROFF	0x713f	/* OF */
     35#define CMD_HALT	0x3876	/* HL */
     36#define CMD_SUSPEND	0x1b1b	/* ZZ */
     37
     38struct spi_slave_system_control_priv {
     39	struct spi_device *spi;
     40	struct completion finished;
     41	struct spi_transfer xfer;
     42	struct spi_message msg;
     43	__be16 cmd;
     44};
     45
     46static
     47int spi_slave_system_control_submit(struct spi_slave_system_control_priv *priv);
     48
     49static void spi_slave_system_control_complete(void *arg)
     50{
     51	struct spi_slave_system_control_priv *priv = arg;
     52	u16 cmd;
     53	int ret;
     54
     55	if (priv->msg.status)
     56		goto terminate;
     57
     58	cmd = be16_to_cpu(priv->cmd);
     59	switch (cmd) {
     60	case CMD_REBOOT:
     61		dev_info(&priv->spi->dev, "Rebooting system...\n");
     62		kernel_restart(NULL);
     63		break;
     64
     65	case CMD_POWEROFF:
     66		dev_info(&priv->spi->dev, "Powering off system...\n");
     67		kernel_power_off();
     68		break;
     69
     70	case CMD_HALT:
     71		dev_info(&priv->spi->dev, "Halting system...\n");
     72		kernel_halt();
     73		break;
     74
     75	case CMD_SUSPEND:
     76		dev_info(&priv->spi->dev, "Suspending system...\n");
     77		pm_suspend(PM_SUSPEND_MEM);
     78		break;
     79
     80	default:
     81		dev_warn(&priv->spi->dev, "Unknown command 0x%x\n", cmd);
     82		break;
     83	}
     84
     85	ret = spi_slave_system_control_submit(priv);
     86	if (ret)
     87		goto terminate;
     88
     89	return;
     90
     91terminate:
     92	dev_info(&priv->spi->dev, "Terminating\n");
     93	complete(&priv->finished);
     94}
     95
     96static
     97int spi_slave_system_control_submit(struct spi_slave_system_control_priv *priv)
     98{
     99	int ret;
    100
    101	spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1);
    102
    103	priv->msg.complete = spi_slave_system_control_complete;
    104	priv->msg.context = priv;
    105
    106	ret = spi_async(priv->spi, &priv->msg);
    107	if (ret)
    108		dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret);
    109
    110	return ret;
    111}
    112
    113static int spi_slave_system_control_probe(struct spi_device *spi)
    114{
    115	struct spi_slave_system_control_priv *priv;
    116	int ret;
    117
    118	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
    119	if (!priv)
    120		return -ENOMEM;
    121
    122	priv->spi = spi;
    123	init_completion(&priv->finished);
    124	priv->xfer.rx_buf = &priv->cmd;
    125	priv->xfer.len = sizeof(priv->cmd);
    126
    127	ret = spi_slave_system_control_submit(priv);
    128	if (ret)
    129		return ret;
    130
    131	spi_set_drvdata(spi, priv);
    132	return 0;
    133}
    134
    135static void spi_slave_system_control_remove(struct spi_device *spi)
    136{
    137	struct spi_slave_system_control_priv *priv = spi_get_drvdata(spi);
    138
    139	spi_slave_abort(spi);
    140	wait_for_completion(&priv->finished);
    141}
    142
    143static struct spi_driver spi_slave_system_control_driver = {
    144	.driver = {
    145		.name	= "spi-slave-system-control",
    146	},
    147	.probe		= spi_slave_system_control_probe,
    148	.remove		= spi_slave_system_control_remove,
    149};
    150module_spi_driver(spi_slave_system_control_driver);
    151
    152MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
    153MODULE_DESCRIPTION("SPI slave handler controlling system state");
    154MODULE_LICENSE("GPL v2");