1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * PowerNV OPAL Power-Shift-Ratio interface
4  *
5  * Copyright 2017 IBM Corp.
6  */
7 
8 #define pr_fmt(fmt)     "opal-psr: " fmt
9 
10 #include <linux/of.h>
11 #include <linux/kobject.h>
12 #include <linux/slab.h>
13 
14 #include <asm/opal.h>
15 
16 static DEFINE_MUTEX(psr_mutex);
17 
18 static struct kobject *psr_kobj;
19 
20 static struct psr_attr {
21 	u32 handle;
22 	struct kobj_attribute attr;
23 } *psr_attrs;
24 
25 static ssize_t psr_show(struct kobject *kobj, struct kobj_attribute *attr,
26 			char *buf)
27 {
28 	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
29 	struct opal_msg msg;
30 	int psr, ret, token;
31 
32 	token = opal_async_get_token_interruptible();
33 	if (token < 0) {
34 		pr_devel("Failed to get token\n");
35 		return token;
36 	}
37 
38 	ret = mutex_lock_interruptible(&psr_mutex);
39 	if (ret)
40 		goto out_token;
41 
42 	ret = opal_get_power_shift_ratio(psr_attr->handle, token,
43 					    (u32 *)__pa(&psr));
44 	switch (ret) {
45 	case OPAL_ASYNC_COMPLETION:
46 		ret = opal_async_wait_response(token, &msg);
47 		if (ret) {
48 			pr_devel("Failed to wait for the async response\n");
49 			ret = -EIO;
50 			goto out;
51 		}
52 		ret = opal_error_code(opal_get_async_rc(msg));
53 		if (!ret) {
54 			ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
55 			if (ret < 0)
56 				ret = -EIO;
57 		}
58 		break;
59 	case OPAL_SUCCESS:
60 		ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
61 		if (ret < 0)
62 			ret = -EIO;
63 		break;
64 	default:
65 		ret = opal_error_code(ret);
66 	}
67 
68 out:
69 	mutex_unlock(&psr_mutex);
70 out_token:
71 	opal_async_release_token(token);
72 	return ret;
73 }
74 
75 static ssize_t psr_store(struct kobject *kobj, struct kobj_attribute *attr,
76 			 const char *buf, size_t count)
77 {
78 	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
79 	struct opal_msg msg;
80 	int psr, ret, token;
81 
82 	ret = kstrtoint(buf, 0, &psr);
83 	if (ret)
84 		return ret;
85 
86 	token = opal_async_get_token_interruptible();
87 	if (token < 0) {
88 		pr_devel("Failed to get token\n");
89 		return token;
90 	}
91 
92 	ret = mutex_lock_interruptible(&psr_mutex);
93 	if (ret)
94 		goto out_token;
95 
96 	ret = opal_set_power_shift_ratio(psr_attr->handle, token, psr);
97 	switch (ret) {
98 	case OPAL_ASYNC_COMPLETION:
99 		ret = opal_async_wait_response(token, &msg);
100 		if (ret) {
101 			pr_devel("Failed to wait for the async response\n");
102 			ret = -EIO;
103 			goto out;
104 		}
105 		ret = opal_error_code(opal_get_async_rc(msg));
106 		if (!ret)
107 			ret = count;
108 		break;
109 	case OPAL_SUCCESS:
110 		ret = count;
111 		break;
112 	default:
113 		ret = opal_error_code(ret);
114 	}
115 
116 out:
117 	mutex_unlock(&psr_mutex);
118 out_token:
119 	opal_async_release_token(token);
120 	return ret;
121 }
122 
123 void __init opal_psr_init(void)
124 {
125 	struct device_node *psr, *node;
126 	int i = 0;
127 
128 	psr = of_find_compatible_node(NULL, NULL,
129 				      "ibm,opal-power-shift-ratio");
130 	if (!psr) {
131 		pr_devel("Power-shift-ratio node not found\n");
132 		return;
133 	}
134 
135 	psr_attrs = kcalloc(of_get_child_count(psr), sizeof(*psr_attrs),
136 			    GFP_KERNEL);
137 	if (!psr_attrs)
138 		goto out_put_psr;
139 
140 	psr_kobj = kobject_create_and_add("psr", opal_kobj);
141 	if (!psr_kobj) {
142 		pr_warn("Failed to create psr kobject\n");
143 		goto out;
144 	}
145 
146 	for_each_child_of_node(psr, node) {
147 		if (of_property_read_u32(node, "handle",
148 					 &psr_attrs[i].handle))
149 			goto out_kobj;
150 
151 		sysfs_attr_init(&psr_attrs[i].attr.attr);
152 		if (of_property_read_string(node, "label",
153 					    &psr_attrs[i].attr.attr.name))
154 			goto out_kobj;
155 		psr_attrs[i].attr.attr.mode = 0664;
156 		psr_attrs[i].attr.show = psr_show;
157 		psr_attrs[i].attr.store = psr_store;
158 		if (sysfs_create_file(psr_kobj, &psr_attrs[i].attr.attr)) {
159 			pr_devel("Failed to create psr sysfs file %s\n",
160 				 psr_attrs[i].attr.attr.name);
161 			goto out_kobj;
162 		}
163 		i++;
164 	}
165 	of_node_put(psr);
166 
167 	return;
168 out_kobj:
169 	of_node_put(node);
170 	kobject_put(psr_kobj);
171 out:
172 	kfree(psr_attrs);
173 out_put_psr:
174 	of_node_put(psr);
175 }
176