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         else if (of_property_read_bool(np, "native-endian"))
  79                 syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;
  80
  81         /*
  82          * search for reg-io-width property in DT. If it is not provided,
  83          * default to 4 bytes. regmap_init_mmio will return an error if values
  84          * are invalid so there is no need to check them here.
  85          */
  86         ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
  87         if (ret)
  88                 reg_io_width = 4;
  89
  90         syscon_config.reg_stride = reg_io_width;
  91         syscon_config.val_bits = reg_io_width * 8;
  92         syscon_config.max_register = resource_size(&res) - reg_io_width;
  93
  94         regmap = regmap_init_mmio(NULL, base, &syscon_config);
  95         if (IS_ERR(regmap)) {
  96                 pr_err("regmap init failed\n");
  97                 ret = PTR_ERR(regmap);
  98                 goto err_regmap;
  99         }
 100
 101         syscon->regmap = regmap;
 102         syscon->np = np;
 103
 104         spin_lock(&syscon_list_slock);
 105         list_add_tail(&syscon->list, &syscon_list);
 106         spin_unlock(&syscon_list_slock);
 107
 108         return syscon;
 109
 110 err_regmap:
 111         iounmap(base);
 112 err_map:
 113         kfree(syscon);
 114         return ERR_PTR(ret);
 115 }
 116
 117 struct regmap *syscon_node_to_regmap(struct device_node *np)
 118 {
 119         struct syscon *entry, *syscon = NULL;
 120
 121         spin_lock(&syscon_list_slock);
 122
 123         list_for_each_entry(entry, &syscon_list, list)
 124                 if (entry->np == np) {
 125                         syscon = entry;
 126                         break;
 127                 }
 128
 129         spin_unlock(&syscon_list_slock);
 130
 131         if (!syscon)
 132                 syscon = of_syscon_register(np);
 133
 134         if (IS_ERR(syscon))
 135                 return ERR_CAST(syscon);
 136
 137         return syscon->regmap;
 138 }
 139 EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
 140
 141 struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
 142 {
 143         struct device_node *syscon_np;
 144         struct regmap *regmap;
 145
 146         syscon_np = of_find_compatible_node(NULL, NULL, s);
 147         if (!syscon_np)
 148                 return ERR_PTR(-ENODEV);
 149
 150         regmap = syscon_node_to_regmap(syscon_np);
 151         of_node_put(syscon_np);
 152
 153         return regmap;
 154 }
 155 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
 156
 157 static int syscon_match_pdevname(struct device *dev, void *data)
 158 {
 159         return !strcmp(dev_name(dev), (const char *)data);
 160 }
 161
 162 struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
 163 {
 164         struct device *dev;
 165         struct syscon *syscon;
 166
 167         dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
 168                                  syscon_match_pdevname);
 169         if (!dev)
 170                 return ERR_PTR(-EPROBE_DEFER);
 171
 172         syscon = dev_get_drvdata(dev);
 173
 174         return syscon->regmap;
 175 }
 176 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);
 177
 178 struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
 179                                         const char *property)
 180 {
 181         struct device_node *syscon_np;
 182         struct regmap *regmap;
 183
 184         if (property)
 185                 syscon_np = of_parse_phandle(np, property, 0);
 186         else
 187                 syscon_np = np;
 188
 189         if (!syscon_np)
 190                 return ERR_PTR(-ENODEV);
 191
 192         regmap = syscon_node_to_regmap(syscon_np);
 193         of_node_put(syscon_np);
 194
 195         return regmap;
 196 }
 197 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
 198
 199 static int syscon_probe(struct platform_device *pdev)
 200 {
 201         struct device *dev = &pdev->dev;
 202         struct syscon_platform_data *pdata = dev_get_platdata(dev);
 203         struct syscon *syscon;
 204         struct regmap_config syscon_config = syscon_regmap_config;
 205         struct resource *res;
 206         void __iomem *base;
 207
 208         syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
 209         if (!syscon)
 210                 return -ENOMEM;
 211
 212         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 213         if (!res)
 214                 return -ENOENT;
 215
 216         base = devm_ioremap(dev, res->start, resource_size(res));
 217         if (!base)
 218                 return -ENOMEM;
 219
 220         syscon_config.max_register = res->end - res->start - 3;
 221         if (pdata)
 222                 syscon_config.name = pdata->label;
 223         syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
 224         if (IS_ERR(syscon->regmap)) {
 225                 dev_err(dev, "regmap init failed\n");
 226                 return PTR_ERR(syscon->regmap);
 227         }
 228
 229         platform_set_drvdata(pdev, syscon);
 230
 231         dev_dbg(dev, "regmap %pR registered\n", res);
 232
 233         return 0;
 234 }
 235
 236 static const struct platform_device_id syscon_ids[] = {
 237         { "syscon", },
 238         { }
 239 };
 240
 241 static struct platform_driver syscon_driver = {
 242         .driver = {
 243                 .name = "syscon",
 244         },
 245         .probe          = syscon_probe,
 246         .id_table       = syscon_ids,
 247 };
 248
 249 static int __init syscon_init(void)
 250 {
 251         return platform_driver_register(&syscon_driver);
 252 }
 253 postcore_initcall(syscon_init);
 254
 255 static void __exit syscon_exit(void)
 256 {
 257         platform_driver_unregister(&syscon_driver);
 258 }
 259 module_exit(syscon_exit);
 260
 261 MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
 262 MODULE_DESCRIPTION("System Control driver");
 263 MODULE_LICENSE("GPL v2");