Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 169f3d595f60cb4071bd044e6cd7c73a9d7f8c61 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
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");