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Release 4.14 drivers/spi/spi-slave-system-control.c

Directory: drivers/spi
/*
 * 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); 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); }

Contributors

PersonTokensPropCommitsCommitProp
Geert Uytterhoeven181100.00%1100.00%
Total181100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Geert Uytterhoeven80100.00%1100.00%
Total80100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Geert Uytterhoeven108100.00%1100.00%
Total108100.00%1100.00%


static int 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); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Geert Uytterhoeven37100.00%1100.00%
Total37100.00%1100.00%

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");

Overall Contributors

PersonTokensPropCommitsCommitProp
Geert Uytterhoeven525100.00%1100.00%
Total525100.00%1100.00%
Directory: drivers/spi
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