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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 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 
 54         if (!of_device_is_compatible(np, "syscon"))
 55                 return ERR_PTR(-EINVAL);
 56 
 57         syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
 58         if (!syscon)
 59                 return ERR_PTR(-ENOMEM);
 60 
 61         base = of_iomap(np, 0);
 62         if (!base) {
 63                 ret = -ENOMEM;
 64                 goto err_map;
 65         }
 66 
 67         /* Parse the device's DT node for an endianness specification */
 68         if (of_property_read_bool(np, "big-endian"))
 69                 syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
 70          else if (of_property_read_bool(np, "little-endian"))
 71                 syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
 72 
 73         /*
 74          * search for reg-io-width property in DT. If it is not provided,
 75          * default to 4 bytes. regmap_init_mmio will return an error if values
 76          * are invalid so there is no need to check them here.
 77          */
 78         ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
 79         if (ret)
 80                 reg_io_width = 4;
 81 
 82         syscon_config.reg_stride = reg_io_width;
 83         syscon_config.val_bits = reg_io_width * 8;
 84 
 85         regmap = regmap_init_mmio(NULL, base, &syscon_config);
 86         if (IS_ERR(regmap)) {
 87                 pr_err("regmap init failed\n");
 88                 ret = PTR_ERR(regmap);
 89                 goto err_regmap;
 90         }
 91 
 92         syscon->regmap = regmap;
 93         syscon->np = np;
 94 
 95         spin_lock(&syscon_list_slock);
 96         list_add_tail(&syscon->list, &syscon_list);
 97         spin_unlock(&syscon_list_slock);
 98 
 99         return syscon;
100 
101 err_regmap:
102         iounmap(base);
103 err_map:
104         kfree(syscon);
105         return ERR_PTR(ret);
106 }
107 
108 struct regmap *syscon_node_to_regmap(struct device_node *np)
109 {
110         struct syscon *entry, *syscon = NULL;
111 
112         spin_lock(&syscon_list_slock);
113 
114         list_for_each_entry(entry, &syscon_list, list)
115                 if (entry->np == np) {
116                         syscon = entry;
117                         break;
118                 }
119 
120         spin_unlock(&syscon_list_slock);
121 
122         if (!syscon)
123                 syscon = of_syscon_register(np);
124 
125         if (IS_ERR(syscon))
126                 return ERR_CAST(syscon);
127 
128         return syscon->regmap;
129 }
130 EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
131 
132 struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
133 {
134         struct device_node *syscon_np;
135         struct regmap *regmap;
136 
137         syscon_np = of_find_compatible_node(NULL, NULL, s);
138         if (!syscon_np)
139                 return ERR_PTR(-ENODEV);
140 
141         regmap = syscon_node_to_regmap(syscon_np);
142         of_node_put(syscon_np);
143 
144         return regmap;
145 }
146 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
147 
148 static int syscon_match_pdevname(struct device *dev, void *data)
149 {
150         return !strcmp(dev_name(dev), (const char *)data);
151 }
152 
153 struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
154 {
155         struct device *dev;
156         struct syscon *syscon;
157 
158         dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
159                                  syscon_match_pdevname);
160         if (!dev)
161                 return ERR_PTR(-EPROBE_DEFER);
162 
163         syscon = dev_get_drvdata(dev);
164 
165         return syscon->regmap;
166 }
167 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);
168 
169 struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
170                                         const char *property)
171 {
172         struct device_node *syscon_np;
173         struct regmap *regmap;
174 
175         if (property)
176                 syscon_np = of_parse_phandle(np, property, 0);
177         else
178                 syscon_np = np;
179 
180         if (!syscon_np)
181                 return ERR_PTR(-ENODEV);
182 
183         regmap = syscon_node_to_regmap(syscon_np);
184         of_node_put(syscon_np);
185 
186         return regmap;
187 }
188 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
189 
190 static int syscon_probe(struct platform_device *pdev)
191 {
192         struct device *dev = &pdev->dev;
193         struct syscon_platform_data *pdata = dev_get_platdata(dev);
194         struct syscon *syscon;
195         struct resource *res;
196         void __iomem *base;
197 
198         syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
199         if (!syscon)
200                 return -ENOMEM;
201 
202         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
203         if (!res)
204                 return -ENOENT;
205 
206         base = devm_ioremap(dev, res->start, resource_size(res));
207         if (!base)
208                 return -ENOMEM;
209 
210         syscon_regmap_config.max_register = res->end - res->start - 3;
211         if (pdata)
212                 syscon_regmap_config.name = pdata->label;
213         syscon->regmap = devm_regmap_init_mmio(dev, base,
214                                         &syscon_regmap_config);
215         if (IS_ERR(syscon->regmap)) {
216                 dev_err(dev, "regmap init failed\n");
217                 return PTR_ERR(syscon->regmap);
218         }
219 
220         platform_set_drvdata(pdev, syscon);
221 
222         dev_dbg(dev, "regmap %pR registered\n", res);
223 
224         return 0;
225 }
226 
227 static const struct platform_device_id syscon_ids[] = {
228         { "syscon", },
229         { }
230 };
231 
232 static struct platform_driver syscon_driver = {
233         .driver = {
234                 .name = "syscon",
235         },
236         .probe          = syscon_probe,
237         .id_table       = syscon_ids,
238 };
239 
240 static int __init syscon_init(void)
241 {
242         return platform_driver_register(&syscon_driver);
243 }
244 postcore_initcall(syscon_init);
245 
246 static void __exit syscon_exit(void)
247 {
248         platform_driver_unregister(&syscon_driver);
249 }
250 module_exit(syscon_exit);
251 
252 MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
253 MODULE_DESCRIPTION("System Control driver");
254 MODULE_LICENSE("GPL v2");
255 

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