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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"); |