1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License version 2 as
4  * published by the Free Software Foundation.
5  *
6  * This program is distributed in the hope that it will be useful,
7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
9  * GNU General Public License for more details.
10  *
11  * Copyright (C) 2012 ARM Limited
12  */
13 
14 #include <linux/delay.h>
15 #include <linux/notifier.h>
16 #include <linux/of.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/reboot.h>
20 #include <linux/stat.h>
21 #include <linux/vexpress.h>
22 
23 static void vexpress_reset_do(struct device *dev, const char *what)
24 {
25 	int err = -ENOENT;
26 	struct regmap *reg = dev_get_drvdata(dev);
27 
28 	if (reg) {
29 		err = regmap_write(reg, 0, 0);
30 		if (!err)
31 			mdelay(1000);
32 	}
33 
34 	dev_emerg(dev, "Unable to %s (%d)\n", what, err);
35 }
36 
37 static struct device *vexpress_power_off_device;
38 
39 static void vexpress_power_off(void)
40 {
41 	vexpress_reset_do(vexpress_power_off_device, "power off");
42 }
43 
44 static struct device *vexpress_restart_device;
45 
46 static int vexpress_restart(struct notifier_block *this, unsigned long mode,
47 			     void *cmd)
48 {
49 	vexpress_reset_do(vexpress_restart_device, "restart");
50 
51 	return NOTIFY_DONE;
52 }
53 
54 static struct notifier_block vexpress_restart_nb = {
55 	.notifier_call = vexpress_restart,
56 	.priority = 128,
57 };
58 
59 static ssize_t vexpress_reset_active_show(struct device *dev,
60 		struct device_attribute *attr, char *buf)
61 {
62 	return sprintf(buf, "%d\n", vexpress_restart_device == dev);
63 }
64 
65 static ssize_t vexpress_reset_active_store(struct device *dev,
66 		struct device_attribute *attr, const char *buf, size_t count)
67 {
68 	long value;
69 	int err = kstrtol(buf, 0, &value);
70 
71 	if (!err && value)
72 		vexpress_restart_device = dev;
73 
74 	return err ? err : count;
75 }
76 
77 static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
78 		   vexpress_reset_active_store);
79 
80 
81 enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };
82 
83 static const struct of_device_id vexpress_reset_of_match[] = {
84 	{
85 		.compatible = "arm,vexpress-reset",
86 		.data = (void *)FUNC_RESET,
87 	}, {
88 		.compatible = "arm,vexpress-shutdown",
89 		.data = (void *)FUNC_SHUTDOWN
90 	}, {
91 		.compatible = "arm,vexpress-reboot",
92 		.data = (void *)FUNC_REBOOT
93 	},
94 	{}
95 };
96 
97 static int _vexpress_register_restart_handler(struct device *dev)
98 {
99 	int err;
100 
101 	vexpress_restart_device = dev;
102 	err = register_restart_handler(&vexpress_restart_nb);
103 	if (err) {
104 		dev_err(dev, "cannot register restart handler (err=%d)\n", err);
105 		return err;
106 	}
107 	device_create_file(dev, &dev_attr_active);
108 
109 	return 0;
110 }
111 
112 static int vexpress_reset_probe(struct platform_device *pdev)
113 {
114 	const struct of_device_id *match =
115 			of_match_device(vexpress_reset_of_match, &pdev->dev);
116 	struct regmap *regmap;
117 	int ret = 0;
118 
119 	if (!match)
120 		return -EINVAL;
121 
122 	regmap = devm_regmap_init_vexpress_config(&pdev->dev);
123 	if (IS_ERR(regmap))
124 		return PTR_ERR(regmap);
125 	dev_set_drvdata(&pdev->dev, regmap);
126 
127 	switch ((enum vexpress_reset_func)match->data) {
128 	case FUNC_SHUTDOWN:
129 		vexpress_power_off_device = &pdev->dev;
130 		pm_power_off = vexpress_power_off;
131 		break;
132 	case FUNC_RESET:
133 		if (!vexpress_restart_device)
134 			ret = _vexpress_register_restart_handler(&pdev->dev);
135 		break;
136 	case FUNC_REBOOT:
137 		ret = _vexpress_register_restart_handler(&pdev->dev);
138 		break;
139 	};
140 
141 	return ret;
142 }
143 
144 static struct platform_driver vexpress_reset_driver = {
145 	.probe = vexpress_reset_probe,
146 	.driver = {
147 		.name = "vexpress-reset",
148 		.of_match_table = vexpress_reset_of_match,
149 	},
150 };
151 
152 static int __init vexpress_reset_init(void)
153 {
154 	return platform_driver_register(&vexpress_reset_driver);
155 }
156 device_initcall(vexpress_reset_init);
157