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");