ce70e06c09
Add an example SPI slave handler to allow remote control of system reboot, power off, halt, and suspend. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Mark Brown <broonie@kernel.org>
154 lines
3.6 KiB
C
154 lines
3.6 KiB
C
/*
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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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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 <geert+renesas@glider.be>");
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MODULE_DESCRIPTION("SPI slave handler controlling system state");
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MODULE_LICENSE("GPL v2");
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