Root/drivers/clk/clkdev.c

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#include <linux/of.h>
23
24static LIST_HEAD(clocks);
25static DEFINE_MUTEX(clocks_mutex);
26
27#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
28struct clk *of_clk_get(struct device_node *np, int index)
29{
30    struct of_phandle_args clkspec;
31    struct clk *clk;
32    int rc;
33
34    if (index < 0)
35        return ERR_PTR(-EINVAL);
36
37    rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
38                    &clkspec);
39    if (rc)
40        return ERR_PTR(rc);
41
42    clk = of_clk_get_from_provider(&clkspec);
43    of_node_put(clkspec.np);
44    return clk;
45}
46EXPORT_SYMBOL(of_clk_get);
47
48/**
49 * of_clk_get_by_name() - Parse and lookup a clock referenced by a device node
50 * @np: pointer to clock consumer node
51 * @name: name of consumer's clock input, or NULL for the first clock reference
52 *
53 * This function parses the clocks and clock-names properties,
54 * and uses them to look up the struct clk from the registered list of clock
55 * providers.
56 */
57struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
58{
59    struct clk *clk = ERR_PTR(-ENOENT);
60
61    /* Walk up the tree of devices looking for a clock that matches */
62    while (np) {
63        int index = 0;
64
65        /*
66         * For named clocks, first look up the name in the
67         * "clock-names" property. If it cannot be found, then
68         * index will be an error code, and of_clk_get() will fail.
69         */
70        if (name)
71            index = of_property_match_string(np, "clock-names", name);
72        clk = of_clk_get(np, index);
73        if (!IS_ERR(clk))
74            break;
75        else if (name && index >= 0) {
76            pr_err("ERROR: could not get clock %s:%s(%i)\n",
77                np->full_name, name ? name : "", index);
78            return clk;
79        }
80
81        /*
82         * No matching clock found on this node. If the parent node
83         * has a "clock-ranges" property, then we can try one of its
84         * clocks.
85         */
86        np = np->parent;
87        if (np && !of_get_property(np, "clock-ranges", NULL))
88            break;
89    }
90
91    return clk;
92}
93EXPORT_SYMBOL(of_clk_get_by_name);
94#endif
95
96/*
97 * Find the correct struct clk for the device and connection ID.
98 * We do slightly fuzzy matching here:
99 * An entry with a NULL ID is assumed to be a wildcard.
100 * If an entry has a device ID, it must match
101 * If an entry has a connection ID, it must match
102 * Then we take the most specific entry - with the following
103 * order of precedence: dev+con > dev only > con only.
104 */
105static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
106{
107    struct clk_lookup *p, *cl = NULL;
108    int match, best_found = 0, best_possible = 0;
109
110    if (dev_id)
111        best_possible += 2;
112    if (con_id)
113        best_possible += 1;
114
115    list_for_each_entry(p, &clocks, node) {
116        match = 0;
117        if (p->dev_id) {
118            if (!dev_id || strcmp(p->dev_id, dev_id))
119                continue;
120            match += 2;
121        }
122        if (p->con_id) {
123            if (!con_id || strcmp(p->con_id, con_id))
124                continue;
125            match += 1;
126        }
127
128        if (match > best_found) {
129            cl = p;
130            if (match != best_possible)
131                best_found = match;
132            else
133                break;
134        }
135    }
136    return cl;
137}
138
139struct clk *clk_get_sys(const char *dev_id, const char *con_id)
140{
141    struct clk_lookup *cl;
142
143    mutex_lock(&clocks_mutex);
144    cl = clk_find(dev_id, con_id);
145    if (cl && !__clk_get(cl->clk))
146        cl = NULL;
147    mutex_unlock(&clocks_mutex);
148
149    return cl ? cl->clk : ERR_PTR(-ENOENT);
150}
151EXPORT_SYMBOL(clk_get_sys);
152
153struct clk *clk_get(struct device *dev, const char *con_id)
154{
155    const char *dev_id = dev ? dev_name(dev) : NULL;
156    struct clk *clk;
157
158    if (dev) {
159        clk = of_clk_get_by_name(dev->of_node, con_id);
160        if (!IS_ERR(clk) && __clk_get(clk))
161            return clk;
162    }
163
164    return clk_get_sys(dev_id, con_id);
165}
166EXPORT_SYMBOL(clk_get);
167
168void clk_put(struct clk *clk)
169{
170    __clk_put(clk);
171}
172EXPORT_SYMBOL(clk_put);
173
174void clkdev_add(struct clk_lookup *cl)
175{
176    mutex_lock(&clocks_mutex);
177    list_add_tail(&cl->node, &clocks);
178    mutex_unlock(&clocks_mutex);
179}
180EXPORT_SYMBOL(clkdev_add);
181
182void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
183{
184    mutex_lock(&clocks_mutex);
185    while (num--) {
186        list_add_tail(&cl->node, &clocks);
187        cl++;
188    }
189    mutex_unlock(&clocks_mutex);
190}
191
192#define MAX_DEV_ID 20
193#define MAX_CON_ID 16
194
195struct clk_lookup_alloc {
196    struct clk_lookup cl;
197    char dev_id[MAX_DEV_ID];
198    char con_id[MAX_CON_ID];
199};
200
201static struct clk_lookup * __init_refok
202vclkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt,
203    va_list ap)
204{
205    struct clk_lookup_alloc *cla;
206
207    cla = __clkdev_alloc(sizeof(*cla));
208    if (!cla)
209        return NULL;
210
211    cla->cl.clk = clk;
212    if (con_id) {
213        strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
214        cla->cl.con_id = cla->con_id;
215    }
216
217    if (dev_fmt) {
218        vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
219        cla->cl.dev_id = cla->dev_id;
220    }
221
222    return &cla->cl;
223}
224
225struct clk_lookup * __init_refok
226clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
227{
228    struct clk_lookup *cl;
229    va_list ap;
230
231    va_start(ap, dev_fmt);
232    cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
233    va_end(ap);
234
235    return cl;
236}
237EXPORT_SYMBOL(clkdev_alloc);
238
239int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
240    struct device *dev)
241{
242    struct clk *r = clk_get(dev, id);
243    struct clk_lookup *l;
244
245    if (IS_ERR(r))
246        return PTR_ERR(r);
247
248    l = clkdev_alloc(r, alias, alias_dev_name);
249    clk_put(r);
250    if (!l)
251        return -ENODEV;
252    clkdev_add(l);
253    return 0;
254}
255EXPORT_SYMBOL(clk_add_alias);
256
257/*
258 * clkdev_drop - remove a clock dynamically allocated
259 */
260void clkdev_drop(struct clk_lookup *cl)
261{
262    mutex_lock(&clocks_mutex);
263    list_del(&cl->node);
264    mutex_unlock(&clocks_mutex);
265    kfree(cl);
266}
267EXPORT_SYMBOL(clkdev_drop);
268
269/**
270 * clk_register_clkdev - register one clock lookup for a struct clk
271 * @clk: struct clk to associate with all clk_lookups
272 * @con_id: connection ID string on device
273 * @dev_id: format string describing device name
274 *
275 * con_id or dev_id may be NULL as a wildcard, just as in the rest of
276 * clkdev.
277 *
278 * To make things easier for mass registration, we detect error clks
279 * from a previous clk_register() call, and return the error code for
280 * those. This is to permit this function to be called immediately
281 * after clk_register().
282 */
283int clk_register_clkdev(struct clk *clk, const char *con_id,
284    const char *dev_fmt, ...)
285{
286    struct clk_lookup *cl;
287    va_list ap;
288
289    if (IS_ERR(clk))
290        return PTR_ERR(clk);
291
292    va_start(ap, dev_fmt);
293    cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
294    va_end(ap);
295
296    if (!cl)
297        return -ENOMEM;
298
299    clkdev_add(cl);
300
301    return 0;
302}
303
304/**
305 * clk_register_clkdevs - register a set of clk_lookup for a struct clk
306 * @clk: struct clk to associate with all clk_lookups
307 * @cl: array of clk_lookup structures with con_id and dev_id pre-initialized
308 * @num: number of clk_lookup structures to register
309 *
310 * To make things easier for mass registration, we detect error clks
311 * from a previous clk_register() call, and return the error code for
312 * those. This is to permit this function to be called immediately
313 * after clk_register().
314 */
315int clk_register_clkdevs(struct clk *clk, struct clk_lookup *cl, size_t num)
316{
317    unsigned i;
318
319    if (IS_ERR(clk))
320        return PTR_ERR(clk);
321
322    for (i = 0; i < num; i++, cl++) {
323        cl->clk = clk;
324        clkdev_add(cl);
325    }
326
327    return 0;
328}
329EXPORT_SYMBOL(clk_register_clkdevs);
330

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