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");