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 static atomic_t vexpress_restart_nb_refcnt = ATOMIC_INIT(0);
39 
40 static void vexpress_power_off(void)
41 {
42 	vexpress_reset_do(vexpress_power_off_device, "power off");
43 }
44 
45 static struct device *vexpress_restart_device;
46 
47 static int vexpress_restart(struct notifier_block *this, unsigned long mode,
48 			     void *cmd)
49 {
50 	vexpress_reset_do(vexpress_restart_device, "restart");
51 
52 	return NOTIFY_DONE;
53 }
54 
55 static struct notifier_block vexpress_restart_nb = {
56 	.notifier_call = vexpress_restart,
57 	.priority = 128,
58 };
59 
60 static ssize_t vexpress_reset_active_show(struct device *dev,
61 		struct device_attribute *attr, char *buf)
62 {
63 	return sprintf(buf, "%d\n", vexpress_restart_device == dev);
64 }
65 
66 static ssize_t vexpress_reset_active_store(struct device *dev,
67 		struct device_attribute *attr, const char *buf, size_t count)
68 {
69 	long value;
70 	int err = kstrtol(buf, 0, &value);
71 
72 	if (!err && value)
73 		vexpress_restart_device = dev;
74 
75 	return err ? err : count;
76 }
77 
78 static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
79 		   vexpress_reset_active_store);
80 
81 
82 enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };
83 
84 static const struct of_device_id vexpress_reset_of_match[] = {
85 	{
86 		.compatible = "arm,vexpress-reset",
87 		.data = (void *)FUNC_RESET,
88 	}, {
89 		.compatible = "arm,vexpress-shutdown",
90 		.data = (void *)FUNC_SHUTDOWN
91 	}, {
92 		.compatible = "arm,vexpress-reboot",
93 		.data = (void *)FUNC_REBOOT
94 	},
95 	{}
96 };
97 
98 static int _vexpress_register_restart_handler(struct device *dev)
99 {
100 	int err;
101 
102 	vexpress_restart_device = dev;
103 	if (atomic_inc_return(&vexpress_restart_nb_refcnt) == 1) {
104 		err = register_restart_handler(&vexpress_restart_nb);
105 		if (err) {
106 			dev_err(dev, "cannot register restart handler (err=%d)\n", err);
107 			atomic_dec(&vexpress_restart_nb_refcnt);
108 			return err;
109 		}
110 	}
111 	device_create_file(dev, &dev_attr_active);
112 
113 	return 0;
114 }
115 
116 static int vexpress_reset_probe(struct platform_device *pdev)
117 {
118 	const struct of_device_id *match =
119 			of_match_device(vexpress_reset_of_match, &pdev->dev);
120 	struct regmap *regmap;
121 	int ret = 0;
122 
123 	if (!match)
124 		return -EINVAL;
125 
126 	regmap = devm_regmap_init_vexpress_config(&pdev->dev);
127 	if (IS_ERR(regmap))
128 		return PTR_ERR(regmap);
129 	dev_set_drvdata(&pdev->dev, regmap);
130 
131 	switch ((enum vexpress_reset_func)match->data) {
132 	case FUNC_SHUTDOWN:
133 		vexpress_power_off_device = &pdev->dev;
134 		pm_power_off = vexpress_power_off;
135 		break;
136 	case FUNC_RESET:
137 		if (!vexpress_restart_device)
138 			ret = _vexpress_register_restart_handler(&pdev->dev);
139 		break;
140 	case FUNC_REBOOT:
141 		ret = _vexpress_register_restart_handler(&pdev->dev);
142 		break;
143 	};
144 
145 	return ret;
146 }
147 
148 static struct platform_driver vexpress_reset_driver = {
149 	.probe = vexpress_reset_probe,
150 	.driver = {
151 		.name = "vexpress-reset",
152 		.of_match_table = vexpress_reset_of_match,
153 	},
154 };
155 
156 static int __init vexpress_reset_init(void)
157 {
158 	return platform_driver_register(&vexpress_reset_driver);
159 }
160 device_initcall(vexpress_reset_init);
161