diff options
Diffstat (limited to 'drivers/spi/spi-slave-system-control.c')
| -rw-r--r-- | drivers/spi/spi-slave-system-control.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/drivers/spi/spi-slave-system-control.c b/drivers/spi/spi-slave-system-control.c new file mode 100644 index 000000000..169f3d595 --- /dev/null +++ b/drivers/spi/spi-slave-system-control.c @@ -0,0 +1,155 @@ +/* + * 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 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; +} + +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"); |