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1/*2 * SPI slave handler controlling system state3 *4 * This SPI slave handler allows remote control of system reboot, power off,5 * halt, and suspend.6 *7 * Copyright (C) 2016-2017 Glider bvba8 *9 * This file is subject to the terms and conditions of the GNU General Public10 * License. See the file "COPYING" in the main directory of this archive11 * for more details.12 *13 * Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote14 * 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, $halt21 */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-segment31 * displays connected to two 74HC595 shift registers32 */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 46static47int 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 96static97int 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_target_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");155