1 /*
2 * drivers/clk/clkdev.c
3 *
4 * Copyright (C) 2008 Russell King.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Helper for the clk API to assist looking up a struct clk.
11 */
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/device.h>
15 #include <linux/list.h>
16 #include <linux/errno.h>
17 #include <linux/err.h>
18 #include <linux/string.h>
19 #include <linux/mutex.h>
20 #include <linux/clk.h>
21 #include <linux/clkdev.h>
22
23 static LIST_HEAD(clocks);
24 static DEFINE_MUTEX(clocks_mutex);
25
26 /*
27 * Find the correct struct clk for the device and connection ID.
28 * We do slightly fuzzy matching here:
29 * An entry with a NULL ID is assumed to be a wildcard.
30 * If an entry has a device ID, it must match
31 * If an entry has a connection ID, it must match
32 * Then we take the most specific entry - with the following
33 * order of precedence: dev+con > dev only > con only.
34 */
clk_find(const char * dev_id,const char * con_id)35 static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
36 {
37 struct clk_lookup *p, *cl = NULL;
38 int match, best = 0;
39
40 list_for_each_entry(p, &clocks, node) {
41 match = 0;
42 if (p->dev_id) {
43 if (!dev_id || strcmp(p->dev_id, dev_id))
44 continue;
45 match += 2;
46 }
47 if (p->con_id) {
48 if (!con_id || strcmp(p->con_id, con_id))
49 continue;
50 match += 1;
51 }
52
53 if (match > best) {
54 cl = p;
55 if (match != 3)
56 best = match;
57 else
58 break;
59 }
60 }
61 return cl;
62 }
63
clk_get_sys(const char * dev_id,const char * con_id)64 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
65 {
66 struct clk_lookup *cl;
67
68 mutex_lock(&clocks_mutex);
69 cl = clk_find(dev_id, con_id);
70 if (cl && !__clk_get(cl->clk))
71 cl = NULL;
72 mutex_unlock(&clocks_mutex);
73
74 return cl ? cl->clk : ERR_PTR(-ENOENT);
75 }
76 EXPORT_SYMBOL(clk_get_sys);
77
clk_get(struct device * dev,const char * con_id)78 struct clk *clk_get(struct device *dev, const char *con_id)
79 {
80 const char *dev_id = dev ? dev_name(dev) : NULL;
81
82 return clk_get_sys(dev_id, con_id);
83 }
84 EXPORT_SYMBOL(clk_get);
85
clk_put(struct clk * clk)86 void clk_put(struct clk *clk)
87 {
88 __clk_put(clk);
89 }
90 EXPORT_SYMBOL(clk_put);
91
clkdev_add(struct clk_lookup * cl)92 void clkdev_add(struct clk_lookup *cl)
93 {
94 mutex_lock(&clocks_mutex);
95 list_add_tail(&cl->node, &clocks);
96 mutex_unlock(&clocks_mutex);
97 }
98 EXPORT_SYMBOL(clkdev_add);
99
clkdev_add_table(struct clk_lookup * cl,size_t num)100 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
101 {
102 mutex_lock(&clocks_mutex);
103 while (num--) {
104 list_add_tail(&cl->node, &clocks);
105 cl++;
106 }
107 mutex_unlock(&clocks_mutex);
108 }
109
110 #define MAX_DEV_ID 20
111 #define MAX_CON_ID 16
112
113 struct clk_lookup_alloc {
114 struct clk_lookup cl;
115 char dev_id[MAX_DEV_ID];
116 char con_id[MAX_CON_ID];
117 };
118
119 struct clk_lookup * __init_refok
clkdev_alloc(struct clk * clk,const char * con_id,const char * dev_fmt,...)120 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
121 {
122 struct clk_lookup_alloc *cla;
123
124 cla = __clkdev_alloc(sizeof(*cla));
125 if (!cla)
126 return NULL;
127
128 cla->cl.clk = clk;
129 if (con_id) {
130 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
131 cla->cl.con_id = cla->con_id;
132 }
133
134 if (dev_fmt) {
135 va_list ap;
136
137 va_start(ap, dev_fmt);
138 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
139 cla->cl.dev_id = cla->dev_id;
140 va_end(ap);
141 }
142
143 return &cla->cl;
144 }
145 EXPORT_SYMBOL(clkdev_alloc);
146
clk_add_alias(const char * alias,const char * alias_dev_name,char * id,struct device * dev)147 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
148 struct device *dev)
149 {
150 struct clk *r = clk_get(dev, id);
151 struct clk_lookup *l;
152
153 if (IS_ERR(r))
154 return PTR_ERR(r);
155
156 l = clkdev_alloc(r, alias, alias_dev_name);
157 clk_put(r);
158 if (!l)
159 return -ENODEV;
160 clkdev_add(l);
161 return 0;
162 }
163 EXPORT_SYMBOL(clk_add_alias);
164
165 /*
166 * clkdev_drop - remove a clock dynamically allocated
167 */
clkdev_drop(struct clk_lookup * cl)168 void clkdev_drop(struct clk_lookup *cl)
169 {
170 mutex_lock(&clocks_mutex);
171 list_del(&cl->node);
172 mutex_unlock(&clocks_mutex);
173 kfree(cl);
174 }
175 EXPORT_SYMBOL(clkdev_drop);
176