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 24 #include "clk.h" 25 26 static LIST_HEAD(clocks); 27 static DEFINE_MUTEX(clocks_mutex); 28 29 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) 30 struct clk *of_clk_get(struct device_node *np, int index) 31 { 32 struct of_phandle_args clkspec; 33 struct clk *clk; 34 int rc; 35 36 if (index < 0) 37 return ERR_PTR(-EINVAL); 38 39 rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index, 40 &clkspec); 41 if (rc) 42 return ERR_PTR(rc); 43 44 of_clk_lock(); 45 clk = __of_clk_get_from_provider(&clkspec); 46 47 if (!IS_ERR(clk) && !__clk_get(clk)) 48 clk = ERR_PTR(-ENOENT); 49 50 of_clk_unlock(); 51 of_node_put(clkspec.np); 52 return clk; 53 } 54 EXPORT_SYMBOL(of_clk_get); 55 56 /** 57 * of_clk_get_by_name() - Parse and lookup a clock referenced by a device node 58 * @np: pointer to clock consumer node 59 * @name: name of consumer's clock input, or NULL for the first clock reference 60 * 61 * This function parses the clocks and clock-names properties, 62 * and uses them to look up the struct clk from the registered list of clock 63 * providers. 64 */ 65 struct clk *of_clk_get_by_name(struct device_node *np, const char *name) 66 { 67 struct clk *clk = ERR_PTR(-ENOENT); 68 69 /* Walk up the tree of devices looking for a clock that matches */ 70 while (np) { 71 int index = 0; 72 73 /* 74 * For named clocks, first look up the name in the 75 * "clock-names" property. If it cannot be found, then 76 * index will be an error code, and of_clk_get() will fail. 77 */ 78 if (name) 79 index = of_property_match_string(np, "clock-names", name); 80 clk = of_clk_get(np, index); 81 if (!IS_ERR(clk)) 82 break; 83 else if (name && index >= 0) { 84 pr_err("ERROR: could not get clock %s:%s(%i)\n", 85 np->full_name, name ? name : "", index); 86 return clk; 87 } 88 89 /* 90 * No matching clock found on this node. If the parent node 91 * has a "clock-ranges" property, then we can try one of its 92 * clocks. 93 */ 94 np = np->parent; 95 if (np && !of_get_property(np, "clock-ranges", NULL)) 96 break; 97 } 98 99 return clk; 100 } 101 EXPORT_SYMBOL(of_clk_get_by_name); 102 #endif 103 104 /* 105 * Find the correct struct clk for the device and connection ID. 106 * We do slightly fuzzy matching here: 107 * An entry with a NULL ID is assumed to be a wildcard. 108 * If an entry has a device ID, it must match 109 * If an entry has a connection ID, it must match 110 * Then we take the most specific entry - with the following 111 * order of precedence: dev+con > dev only > con only. 112 */ 113 static struct clk_lookup *clk_find(const char *dev_id, const char *con_id) 114 { 115 struct clk_lookup *p, *cl = NULL; 116 int match, best_found = 0, best_possible = 0; 117 118 if (dev_id) 119 best_possible += 2; 120 if (con_id) 121 best_possible += 1; 122 123 list_for_each_entry(p, &clocks, node) { 124 match = 0; 125 if (p->dev_id) { 126 if (!dev_id || strcmp(p->dev_id, dev_id)) 127 continue; 128 match += 2; 129 } 130 if (p->con_id) { 131 if (!con_id || strcmp(p->con_id, con_id)) 132 continue; 133 match += 1; 134 } 135 136 if (match > best_found) { 137 cl = p; 138 if (match != best_possible) 139 best_found = match; 140 else 141 break; 142 } 143 } 144 return cl; 145 } 146 147 struct clk *clk_get_sys(const char *dev_id, const char *con_id) 148 { 149 struct clk_lookup *cl; 150 151 mutex_lock(&clocks_mutex); 152 cl = clk_find(dev_id, con_id); 153 if (cl && !__clk_get(cl->clk)) 154 cl = NULL; 155 mutex_unlock(&clocks_mutex); 156 157 return cl ? cl->clk : ERR_PTR(-ENOENT); 158 } 159 EXPORT_SYMBOL(clk_get_sys); 160 161 struct clk *clk_get(struct device *dev, const char *con_id) 162 { 163 const char *dev_id = dev ? dev_name(dev) : NULL; 164 struct clk *clk; 165 166 if (dev) { 167 clk = of_clk_get_by_name(dev->of_node, con_id); 168 if (!IS_ERR(clk)) 169 return clk; 170 } 171 172 return clk_get_sys(dev_id, con_id); 173 } 174 EXPORT_SYMBOL(clk_get); 175 176 void clk_put(struct clk *clk) 177 { 178 __clk_put(clk); 179 } 180 EXPORT_SYMBOL(clk_put); 181 182 void clkdev_add(struct clk_lookup *cl) 183 { 184 mutex_lock(&clocks_mutex); 185 list_add_tail(&cl->node, &clocks); 186 mutex_unlock(&clocks_mutex); 187 } 188 EXPORT_SYMBOL(clkdev_add); 189 190 void __init clkdev_add_table(struct clk_lookup *cl, size_t num) 191 { 192 mutex_lock(&clocks_mutex); 193 while (num--) { 194 list_add_tail(&cl->node, &clocks); 195 cl++; 196 } 197 mutex_unlock(&clocks_mutex); 198 } 199 200 #define MAX_DEV_ID 20 201 #define MAX_CON_ID 16 202 203 struct clk_lookup_alloc { 204 struct clk_lookup cl; 205 char dev_id[MAX_DEV_ID]; 206 char con_id[MAX_CON_ID]; 207 }; 208 209 static struct clk_lookup * __init_refok 210 vclkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, 211 va_list ap) 212 { 213 struct clk_lookup_alloc *cla; 214 215 cla = __clkdev_alloc(sizeof(*cla)); 216 if (!cla) 217 return NULL; 218 219 cla->cl.clk = clk; 220 if (con_id) { 221 strlcpy(cla->con_id, con_id, sizeof(cla->con_id)); 222 cla->cl.con_id = cla->con_id; 223 } 224 225 if (dev_fmt) { 226 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap); 227 cla->cl.dev_id = cla->dev_id; 228 } 229 230 return &cla->cl; 231 } 232 233 struct clk_lookup * __init_refok 234 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...) 235 { 236 struct clk_lookup *cl; 237 va_list ap; 238 239 va_start(ap, dev_fmt); 240 cl = vclkdev_alloc(clk, con_id, dev_fmt, ap); 241 va_end(ap); 242 243 return cl; 244 } 245 EXPORT_SYMBOL(clkdev_alloc); 246 247 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id, 248 struct device *dev) 249 { 250 struct clk *r = clk_get(dev, id); 251 struct clk_lookup *l; 252 253 if (IS_ERR(r)) 254 return PTR_ERR(r); 255 256 l = clkdev_alloc(r, alias, alias_dev_name); 257 clk_put(r); 258 if (!l) 259 return -ENODEV; 260 clkdev_add(l); 261 return 0; 262 } 263 EXPORT_SYMBOL(clk_add_alias); 264 265 /* 266 * clkdev_drop - remove a clock dynamically allocated 267 */ 268 void clkdev_drop(struct clk_lookup *cl) 269 { 270 mutex_lock(&clocks_mutex); 271 list_del(&cl->node); 272 mutex_unlock(&clocks_mutex); 273 kfree(cl); 274 } 275 EXPORT_SYMBOL(clkdev_drop); 276 277 /** 278 * clk_register_clkdev - register one clock lookup for a struct clk 279 * @clk: struct clk to associate with all clk_lookups 280 * @con_id: connection ID string on device 281 * @dev_id: format string describing device name 282 * 283 * con_id or dev_id may be NULL as a wildcard, just as in the rest of 284 * clkdev. 285 * 286 * To make things easier for mass registration, we detect error clks 287 * from a previous clk_register() call, and return the error code for 288 * those. This is to permit this function to be called immediately 289 * after clk_register(). 290 */ 291 int clk_register_clkdev(struct clk *clk, const char *con_id, 292 const char *dev_fmt, ...) 293 { 294 struct clk_lookup *cl; 295 va_list ap; 296 297 if (IS_ERR(clk)) 298 return PTR_ERR(clk); 299 300 va_start(ap, dev_fmt); 301 cl = vclkdev_alloc(clk, con_id, dev_fmt, ap); 302 va_end(ap); 303 304 if (!cl) 305 return -ENOMEM; 306 307 clkdev_add(cl); 308 309 return 0; 310 } 311 312 /** 313 * clk_register_clkdevs - register a set of clk_lookup for a struct clk 314 * @clk: struct clk to associate with all clk_lookups 315 * @cl: array of clk_lookup structures with con_id and dev_id pre-initialized 316 * @num: number of clk_lookup structures to register 317 * 318 * To make things easier for mass registration, we detect error clks 319 * from a previous clk_register() call, and return the error code for 320 * those. This is to permit this function to be called immediately 321 * after clk_register(). 322 */ 323 int clk_register_clkdevs(struct clk *clk, struct clk_lookup *cl, size_t num) 324 { 325 unsigned i; 326 327 if (IS_ERR(clk)) 328 return PTR_ERR(clk); 329 330 for (i = 0; i < num; i++, cl++) { 331 cl->clk = clk; 332 clkdev_add(cl); 333 } 334 335 return 0; 336 } 337 EXPORT_SYMBOL(clk_register_clkdevs); 338