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155 lines
3.6 KiB
155 lines
3.6 KiB
/* |
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* SPI slave handler controlling system state |
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* |
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* This SPI slave handler allows remote control of system reboot, power off, |
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* halt, and suspend. |
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* |
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* Copyright (C) 2016-2017 Glider bvba |
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* |
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* This file is subject to the terms and conditions of the GNU General Public |
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* License. See the file "COPYING" in the main directory of this archive |
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* for more details. |
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* |
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* Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote |
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* system): |
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* |
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* # reboot='\x7c\x50' |
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* # poweroff='\x71\x3f' |
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* # halt='\x38\x76' |
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* # suspend='\x1b\x1b' |
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* # spidev_test -D /dev/spidev2.0 -p $suspend # or $reboot, $poweroff, $halt |
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*/ |
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#include <linux/completion.h> |
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#include <linux/module.h> |
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#include <linux/reboot.h> |
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#include <linux/suspend.h> |
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#include <linux/spi/spi.h> |
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/* |
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* The numbers are chosen to display something human-readable on two 7-segment |
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* displays connected to two 74HC595 shift registers |
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*/ |
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#define CMD_REBOOT 0x7c50 /* rb */ |
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#define CMD_POWEROFF 0x713f /* OF */ |
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#define CMD_HALT 0x3876 /* HL */ |
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#define CMD_SUSPEND 0x1b1b /* ZZ */ |
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struct spi_slave_system_control_priv { |
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struct spi_device *spi; |
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struct completion finished; |
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struct spi_transfer xfer; |
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struct spi_message msg; |
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__be16 cmd; |
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}; |
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static |
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int spi_slave_system_control_submit(struct spi_slave_system_control_priv *priv); |
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static void spi_slave_system_control_complete(void *arg) |
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{ |
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struct spi_slave_system_control_priv *priv = arg; |
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u16 cmd; |
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int ret; |
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if (priv->msg.status) |
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goto terminate; |
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cmd = be16_to_cpu(priv->cmd); |
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switch (cmd) { |
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case CMD_REBOOT: |
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dev_info(&priv->spi->dev, "Rebooting system...\n"); |
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kernel_restart(NULL); |
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break; |
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case CMD_POWEROFF: |
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dev_info(&priv->spi->dev, "Powering off system...\n"); |
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kernel_power_off(); |
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break; |
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case CMD_HALT: |
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dev_info(&priv->spi->dev, "Halting system...\n"); |
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kernel_halt(); |
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break; |
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case CMD_SUSPEND: |
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dev_info(&priv->spi->dev, "Suspending system...\n"); |
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pm_suspend(PM_SUSPEND_MEM); |
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break; |
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default: |
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dev_warn(&priv->spi->dev, "Unknown command 0x%x\n", cmd); |
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break; |
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} |
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ret = spi_slave_system_control_submit(priv); |
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if (ret) |
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goto terminate; |
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return; |
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terminate: |
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dev_info(&priv->spi->dev, "Terminating\n"); |
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complete(&priv->finished); |
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} |
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static |
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int spi_slave_system_control_submit(struct spi_slave_system_control_priv *priv) |
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{ |
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int ret; |
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spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1); |
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priv->msg.complete = spi_slave_system_control_complete; |
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priv->msg.context = priv; |
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ret = spi_async(priv->spi, &priv->msg); |
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if (ret) |
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dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret); |
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return ret; |
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} |
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static int spi_slave_system_control_probe(struct spi_device *spi) |
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{ |
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struct spi_slave_system_control_priv *priv; |
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int ret; |
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priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL); |
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if (!priv) |
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return -ENOMEM; |
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priv->spi = spi; |
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init_completion(&priv->finished); |
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priv->xfer.rx_buf = &priv->cmd; |
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priv->xfer.len = sizeof(priv->cmd); |
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ret = spi_slave_system_control_submit(priv); |
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if (ret) |
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return ret; |
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spi_set_drvdata(spi, priv); |
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return 0; |
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} |
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static int spi_slave_system_control_remove(struct spi_device *spi) |
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{ |
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struct spi_slave_system_control_priv *priv = spi_get_drvdata(spi); |
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spi_slave_abort(spi); |
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wait_for_completion(&priv->finished); |
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return 0; |
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} |
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static struct spi_driver spi_slave_system_control_driver = { |
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.driver = { |
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.name = "spi-slave-system-control", |
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}, |
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.probe = spi_slave_system_control_probe, |
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.remove = spi_slave_system_control_remove, |
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}; |
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module_spi_driver(spi_slave_system_control_driver); |
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MODULE_AUTHOR("Geert Uytterhoeven <[email protected]>"); |
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MODULE_DESCRIPTION("SPI slave handler controlling system state"); |
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MODULE_LICENSE("GPL v2");
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