1 /*
2  * PowerNV OPAL Power-Shift-Ratio interface
3  *
4  * Copyright 2017 IBM Corp.
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #define pr_fmt(fmt)     "opal-psr: " fmt
13 
14 #include <linux/of.h>
15 #include <linux/kobject.h>
16 #include <linux/slab.h>
17 
18 #include <asm/opal.h>
19 
20 DEFINE_MUTEX(psr_mutex);
21 
22 static struct kobject *psr_kobj;
23 
24 struct psr_attr {
25 	u32 handle;
26 	struct kobj_attribute attr;
27 } *psr_attrs;
28 
29 static ssize_t psr_show(struct kobject *kobj, struct kobj_attribute *attr,
30 			char *buf)
31 {
32 	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
33 	struct opal_msg msg;
34 	int psr, ret, token;
35 
36 	token = opal_async_get_token_interruptible();
37 	if (token < 0) {
38 		pr_devel("Failed to get token\n");
39 		return token;
40 	}
41 
42 	ret = mutex_lock_interruptible(&psr_mutex);
43 	if (ret)
44 		goto out_token;
45 
46 	ret = opal_get_power_shift_ratio(psr_attr->handle, token,
47 					    (u32 *)__pa(&psr));
48 	switch (ret) {
49 	case OPAL_ASYNC_COMPLETION:
50 		ret = opal_async_wait_response(token, &msg);
51 		if (ret) {
52 			pr_devel("Failed to wait for the async response\n");
53 			ret = -EIO;
54 			goto out;
55 		}
56 		ret = opal_error_code(opal_get_async_rc(msg));
57 		if (!ret) {
58 			ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
59 			if (ret < 0)
60 				ret = -EIO;
61 		}
62 		break;
63 	case OPAL_SUCCESS:
64 		ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
65 		if (ret < 0)
66 			ret = -EIO;
67 		break;
68 	default:
69 		ret = opal_error_code(ret);
70 	}
71 
72 out:
73 	mutex_unlock(&psr_mutex);
74 out_token:
75 	opal_async_release_token(token);
76 	return ret;
77 }
78 
79 static ssize_t psr_store(struct kobject *kobj, struct kobj_attribute *attr,
80 			 const char *buf, size_t count)
81 {
82 	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
83 	struct opal_msg msg;
84 	int psr, ret, token;
85 
86 	ret = kstrtoint(buf, 0, &psr);
87 	if (ret)
88 		return ret;
89 
90 	token = opal_async_get_token_interruptible();
91 	if (token < 0) {
92 		pr_devel("Failed to get token\n");
93 		return token;
94 	}
95 
96 	ret = mutex_lock_interruptible(&psr_mutex);
97 	if (ret)
98 		goto out_token;
99 
100 	ret = opal_set_power_shift_ratio(psr_attr->handle, token, psr);
101 	switch (ret) {
102 	case OPAL_ASYNC_COMPLETION:
103 		ret = opal_async_wait_response(token, &msg);
104 		if (ret) {
105 			pr_devel("Failed to wait for the async response\n");
106 			ret = -EIO;
107 			goto out;
108 		}
109 		ret = opal_error_code(opal_get_async_rc(msg));
110 		if (!ret)
111 			ret = count;
112 		break;
113 	case OPAL_SUCCESS:
114 		ret = count;
115 		break;
116 	default:
117 		ret = opal_error_code(ret);
118 	}
119 
120 out:
121 	mutex_unlock(&psr_mutex);
122 out_token:
123 	opal_async_release_token(token);
124 	return ret;
125 }
126 
127 void __init opal_psr_init(void)
128 {
129 	struct device_node *psr, *node;
130 	int i = 0;
131 
132 	psr = of_find_compatible_node(NULL, NULL,
133 				      "ibm,opal-power-shift-ratio");
134 	if (!psr) {
135 		pr_devel("Power-shift-ratio node not found\n");
136 		return;
137 	}
138 
139 	psr_attrs = kcalloc(of_get_child_count(psr), sizeof(*psr_attrs),
140 			    GFP_KERNEL);
141 	if (!psr_attrs)
142 		return;
143 
144 	psr_kobj = kobject_create_and_add("psr", opal_kobj);
145 	if (!psr_kobj) {
146 		pr_warn("Failed to create psr kobject\n");
147 		goto out;
148 	}
149 
150 	for_each_child_of_node(psr, node) {
151 		if (of_property_read_u32(node, "handle",
152 					 &psr_attrs[i].handle))
153 			goto out_kobj;
154 
155 		sysfs_attr_init(&psr_attrs[i].attr.attr);
156 		if (of_property_read_string(node, "label",
157 					    &psr_attrs[i].attr.attr.name))
158 			goto out_kobj;
159 		psr_attrs[i].attr.attr.mode = 0664;
160 		psr_attrs[i].attr.show = psr_show;
161 		psr_attrs[i].attr.store = psr_store;
162 		if (sysfs_create_file(psr_kobj, &psr_attrs[i].attr.attr)) {
163 			pr_devel("Failed to create psr sysfs file %s\n",
164 				 psr_attrs[i].attr.attr.name);
165 			goto out_kobj;
166 		}
167 		i++;
168 	}
169 
170 	return;
171 out_kobj:
172 	kobject_put(psr_kobj);
173 out:
174 	kfree(psr_attrs);
175 }
176