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Linux/drivers/mfd/syscon.c

  1 /*
  2  * System Control Driver
  3  *
  4  * Copyright (C) 2012 Freescale Semiconductor, Inc.
  5  * Copyright (C) 2012 Linaro Ltd.
  6  *
  7  * Author: Dong Aisheng <dong.aisheng@linaro.org>
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License as published by
 11  * the Free Software Foundation; either version 2 of the License, or
 12  * (at your option) any later version.
 13  */
 14 
 15 #include <linux/err.h>
 16 #include <linux/io.h>
 17 #include <linux/module.h>
 18 #include <linux/list.h>
 19 #include <linux/of.h>
 20 #include <linux/of_address.h>
 21 #include <linux/of_platform.h>
 22 #include <linux/platform_data/syscon.h>
 23 #include <linux/platform_device.h>
 24 #include <linux/regmap.h>
 25 #include <linux/mfd/syscon.h>
 26 #include <linux/slab.h>
 27 
 28 static struct platform_driver syscon_driver;
 29 
 30 static DEFINE_SPINLOCK(syscon_list_slock);
 31 static LIST_HEAD(syscon_list);
 32 
 33 struct syscon {
 34         struct device_node *np;
 35         struct regmap *regmap;
 36         struct list_head list;
 37 };
 38 
 39 static const struct regmap_config syscon_regmap_config = {
 40         .reg_bits = 32,
 41         .val_bits = 32,
 42         .reg_stride = 4,
 43 };
 44 
 45 static struct syscon *of_syscon_register(struct device_node *np)
 46 {
 47         struct syscon *syscon;
 48         struct regmap *regmap;
 49         void __iomem *base;
 50         u32 reg_io_width;
 51         int ret;
 52         struct regmap_config syscon_config = syscon_regmap_config;
 53         struct resource res;
 54 
 55         if (!of_device_is_compatible(np, "syscon"))
 56                 return ERR_PTR(-EINVAL);
 57 
 58         syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
 59         if (!syscon)
 60                 return ERR_PTR(-ENOMEM);
 61 
 62         if (of_address_to_resource(np, 0, &res)) {
 63                 ret = -ENOMEM;
 64                 goto err_map;
 65         }
 66 
 67         base = ioremap(res.start, resource_size(&res));
 68         if (!base) {
 69                 ret = -ENOMEM;
 70                 goto err_map;
 71         }
 72 
 73         /* Parse the device's DT node for an endianness specification */
 74         if (of_property_read_bool(np, "big-endian"))
 75                 syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
 76          else if (of_property_read_bool(np, "little-endian"))
 77                 syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
 78 
 79         /*
 80          * search for reg-io-width property in DT. If it is not provided,
 81          * default to 4 bytes. regmap_init_mmio will return an error if values
 82          * are invalid so there is no need to check them here.
 83          */
 84         ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
 85         if (ret)
 86                 reg_io_width = 4;
 87 
 88         syscon_config.reg_stride = reg_io_width;
 89         syscon_config.val_bits = reg_io_width * 8;
 90         syscon_config.max_register = resource_size(&res) - reg_io_width;
 91 
 92         regmap = regmap_init_mmio(NULL, base, &syscon_config);
 93         if (IS_ERR(regmap)) {
 94                 pr_err("regmap init failed\n");
 95                 ret = PTR_ERR(regmap);
 96                 goto err_regmap;
 97         }
 98 
 99         syscon->regmap = regmap;
100         syscon->np = np;
101 
102         spin_lock(&syscon_list_slock);
103         list_add_tail(&syscon->list, &syscon_list);
104         spin_unlock(&syscon_list_slock);
105 
106         return syscon;
107 
108 err_regmap:
109         iounmap(base);
110 err_map:
111         kfree(syscon);
112         return ERR_PTR(ret);
113 }
114 
115 struct regmap *syscon_node_to_regmap(struct device_node *np)
116 {
117         struct syscon *entry, *syscon = NULL;
118 
119         spin_lock(&syscon_list_slock);
120 
121         list_for_each_entry(entry, &syscon_list, list)
122                 if (entry->np == np) {
123                         syscon = entry;
124                         break;
125                 }
126 
127         spin_unlock(&syscon_list_slock);
128 
129         if (!syscon)
130                 syscon = of_syscon_register(np);
131 
132         if (IS_ERR(syscon))
133                 return ERR_CAST(syscon);
134 
135         return syscon->regmap;
136 }
137 EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
138 
139 struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
140 {
141         struct device_node *syscon_np;
142         struct regmap *regmap;
143 
144         syscon_np = of_find_compatible_node(NULL, NULL, s);
145         if (!syscon_np)
146                 return ERR_PTR(-ENODEV);
147 
148         regmap = syscon_node_to_regmap(syscon_np);
149         of_node_put(syscon_np);
150 
151         return regmap;
152 }
153 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
154 
155 static int syscon_match_pdevname(struct device *dev, void *data)
156 {
157         return !strcmp(dev_name(dev), (const char *)data);
158 }
159 
160 struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
161 {
162         struct device *dev;
163         struct syscon *syscon;
164 
165         dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
166                                  syscon_match_pdevname);
167         if (!dev)
168                 return ERR_PTR(-EPROBE_DEFER);
169 
170         syscon = dev_get_drvdata(dev);
171 
172         return syscon->regmap;
173 }
174 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);
175 
176 struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
177                                         const char *property)
178 {
179         struct device_node *syscon_np;
180         struct regmap *regmap;
181 
182         if (property)
183                 syscon_np = of_parse_phandle(np, property, 0);
184         else
185                 syscon_np = np;
186 
187         if (!syscon_np)
188                 return ERR_PTR(-ENODEV);
189 
190         regmap = syscon_node_to_regmap(syscon_np);
191         of_node_put(syscon_np);
192 
193         return regmap;
194 }
195 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
196 
197 static int syscon_probe(struct platform_device *pdev)
198 {
199         struct device *dev = &pdev->dev;
200         struct syscon_platform_data *pdata = dev_get_platdata(dev);
201         struct syscon *syscon;
202         struct regmap_config syscon_config = syscon_regmap_config;
203         struct resource *res;
204         void __iomem *base;
205 
206         syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
207         if (!syscon)
208                 return -ENOMEM;
209 
210         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
211         if (!res)
212                 return -ENOENT;
213 
214         base = devm_ioremap(dev, res->start, resource_size(res));
215         if (!base)
216                 return -ENOMEM;
217 
218         syscon_config.max_register = res->end - res->start - 3;
219         if (pdata)
220                 syscon_config.name = pdata->label;
221         syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
222         if (IS_ERR(syscon->regmap)) {
223                 dev_err(dev, "regmap init failed\n");
224                 return PTR_ERR(syscon->regmap);
225         }
226 
227         platform_set_drvdata(pdev, syscon);
228 
229         dev_dbg(dev, "regmap %pR registered\n", res);
230 
231         return 0;
232 }
233 
234 static const struct platform_device_id syscon_ids[] = {
235         { "syscon", },
236         { }
237 };
238 
239 static struct platform_driver syscon_driver = {
240         .driver = {
241                 .name = "syscon",
242         },
243         .probe          = syscon_probe,
244         .id_table       = syscon_ids,
245 };
246 
247 static int __init syscon_init(void)
248 {
249         return platform_driver_register(&syscon_driver);
250 }
251 postcore_initcall(syscon_init);
252 
253 static void __exit syscon_exit(void)
254 {
255         platform_driver_unregister(&syscon_driver);
256 }
257 module_exit(syscon_exit);
258 
259 MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
260 MODULE_DESCRIPTION("System Control driver");
261 MODULE_LICENSE("GPL v2");
262 

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