[mirror_ubuntu-artful-kernel.git] / drivers / spi / spi-slave-system-control.c

/*
 * 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);
}

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");
Commit	Line	Data
ce70e06c GU	1	/*
	2	* SPI slave handler controlling system state
	3	*
	4	* This SPI slave handler allows remote control of system reboot, power off,
	5	* halt, and suspend.
	6	*
	7	* Copyright (C) 2016-2017 Glider bvba
	8	*
	9	* This file is subject to the terms and conditions of the GNU General Public
	10	* License. See the file "COPYING" in the main directory of this archive
	11	* for more details.
	12	*
	13	* Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote
	14	* system):
	15	*
	16	* # reboot='\x7c\x50'
	17	* # poweroff='\x71\x3f'
	18	* # halt='\x38\x76'
	19	* # suspend='\x1b\x1b'
	20	* # spidev_test -D /dev/spidev2.0 -p $suspend # or $reboot, $poweroff, $halt
	21	*/
	22
	23	#include <linux/completion.h>
	24	#include <linux/module.h>
	25	#include <linux/reboot.h>
	26	#include <linux/suspend.h>
	27	#include <linux/spi/spi.h>
	28
	29	/*
	30	* The numbers are chosen to display something human-readable on two 7-segment
	31	* displays connected to two 74HC595 shift registers
	32	*/
	33	#define CMD_REBOOT 0x7c50 /* rb */
	34	#define CMD_POWEROFF 0x713f /* OF */
	35	#define CMD_HALT 0x3876 /* HL */
	36	#define CMD_SUSPEND 0x1b1b /* ZZ */
	37
	38	struct spi_slave_system_control_priv {
	39	struct spi_device *spi;
	40	struct completion finished;
	41	struct spi_transfer xfer;
	42	struct spi_message msg;
	43	__be16 cmd;
	44	};
	45
	46	static
	47	int spi_slave_system_control_submit(struct spi_slave_system_control_priv *priv);
	48
	49	static void spi_slave_system_control_complete(void *arg)
	50	{
	51	struct spi_slave_system_control_priv *priv = arg;
	52	u16 cmd;
	53	int ret;
	54
	55	if (priv->msg.status)
	56	goto terminate;
	57
	58	cmd = be16_to_cpu(priv->cmd);
	59	switch (cmd) {
	60	case CMD_REBOOT:
	61	dev_info(&priv->spi->dev, "Rebooting system...\n");
	62	kernel_restart(NULL);
	63
	64	case CMD_POWEROFF:
65	dev_info(&priv->spi->dev, "Powering off system...\n");
66	kernel_power_off();
67	break;
68
69	case CMD_HALT:
70	dev_info(&priv->spi->dev, "Halting system...\n");
71	kernel_halt();
72	break;
73
74	case CMD_SUSPEND:
75	dev_info(&priv->spi->dev, "Suspending system...\n");
76	pm_suspend(PM_SUSPEND_MEM);
77	break;
78
79	default:
80	dev_warn(&priv->spi->dev, "Unknown command 0x%x\n", cmd);
81	break;
82	}
83
84	ret = spi_slave_system_control_submit(priv);
85	if (ret)
86	goto terminate;
87
88	return;
89
90	terminate:
91	dev_info(&priv->spi->dev, "Terminating\n");
92	complete(&priv->finished);
93	}
94
95	static
96	int spi_slave_system_control_submit(struct spi_slave_system_control_priv *priv)
97	{
98	int ret;
99
100	spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1);
101
102	priv->msg.complete = spi_slave_system_control_complete;
103	priv->msg.context = priv;
104
105	ret = spi_async(priv->spi, &priv->msg);
106	if (ret)
107	dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret);
108
109	return ret;
110	}
111
112	static int spi_slave_system_control_probe(struct spi_device *spi)
113	{
114	struct spi_slave_system_control_priv *priv;
115	int ret;
116
117	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
118	if (!priv)
119	return -ENOMEM;
120
121	priv->spi = spi;
122	init_completion(&priv->finished);
123	priv->xfer.rx_buf = &priv->cmd;
124	priv->xfer.len = sizeof(priv->cmd);
125
126	ret = spi_slave_system_control_submit(priv);
127	if (ret)
128	return ret;
129
130	spi_set_drvdata(spi, priv);
131	return 0;
132	}
133
134	static int spi_slave_system_control_remove(struct spi_device *spi)
135	{
136	struct spi_slave_system_control_priv *priv = spi_get_drvdata(spi);
137
138	spi_slave_abort(spi);
139	wait_for_completion(&priv->finished);
140	return 0;
141	}
142
143	static struct spi_driver spi_slave_system_control_driver = {
144	.driver = {
145	.name = "spi-slave-system-control",
146	},
147	.probe = spi_slave_system_control_probe,
148	.remove = spi_slave_system_control_remove,
149	};
150	module_spi_driver(spi_slave_system_control_driver);
151
152	MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
153	MODULE_DESCRIPTION("SPI slave handler controlling system state");
154	MODULE_LICENSE("GPL v2");