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