drivers/nvmem/nvmem-sysfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2019, Linaro Limited
   4  */
   5 #include "nvmem.h"
   6
   7 static const char * const nvmem_type_str[] = {
   8         [NVMEM_TYPE_UNKNOWN] = "Unknown",
   9         [NVMEM_TYPE_EEPROM] = "EEPROM",
  10         [NVMEM_TYPE_OTP] = "OTP",
  11         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
  12 };
  13
  14 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  15 static struct lock_class_key eeprom_lock_key;
  16 #endif
  17
  18 static ssize_t type_show(struct device *dev,
  19                          struct device_attribute *attr, char *buf)
  20 {
  21         struct nvmem_device *nvmem = to_nvmem_device(dev);
  22
  23         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
  24 }
  25
  26 static DEVICE_ATTR_RO(type);
  27
  28 static struct attribute *nvmem_attrs[] = {
  29         &dev_attr_type.attr,
  30         NULL,
  31 };
  32
  33 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
  34                                     struct bin_attribute *attr,
  35                                     char *buf, loff_t pos, size_t count)
  36 {
  37         struct device *dev;
  38         struct nvmem_device *nvmem;
  39         int rc;
  40
  41         if (attr->private)
  42                 dev = attr->private;
  43         else
  44                 dev = container_of(kobj, struct device, kobj);
  45         nvmem = to_nvmem_device(dev);
  46
  47         /* Stop the user from reading */
  48         if (pos >= nvmem->size)
  49                 return 0;
  50
  51         if (count < nvmem->word_size)
  52                 return -EINVAL;
  53
  54         if (pos + count > nvmem->size)
  55                 count = nvmem->size - pos;
  56
  57         count = round_down(count, nvmem->word_size);
  58
  59         rc = nvmem->reg_read(nvmem->priv, pos, buf, count);
  60
  61         if (rc)
  62                 return rc;
  63
  64         return count;
  65 }
  66
  67 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
  68                                      struct bin_attribute *attr,
  69                                      char *buf, loff_t pos, size_t count)
  70 {
  71         struct device *dev;
  72         struct nvmem_device *nvmem;
  73         int rc;
  74
  75         if (attr->private)
  76                 dev = attr->private;
  77         else
  78                 dev = container_of(kobj, struct device, kobj);
  79         nvmem = to_nvmem_device(dev);
  80
  81         /* Stop the user from writing */
  82         if (pos >= nvmem->size)
  83                 return -EFBIG;
  84
  85         if (count < nvmem->word_size)
  86                 return -EINVAL;
  87
  88         if (pos + count > nvmem->size)
  89                 count = nvmem->size - pos;
  90
  91         count = round_down(count, nvmem->word_size);
  92
  93         rc = nvmem->reg_write(nvmem->priv, pos, buf, count);
  94
  95         if (rc)
  96                 return rc;
  97
  98         return count;
  99 }
 100
 101 /* default read/write permissions */
 102 static struct bin_attribute bin_attr_rw_nvmem = {
 103         .attr   = {
 104                 .name   = "nvmem",
 105                 .mode   = 0644,
 106         },
 107         .read   = bin_attr_nvmem_read,
 108         .write  = bin_attr_nvmem_write,
 109 };
 110
 111 static struct bin_attribute *nvmem_bin_rw_attributes[] = {
 112         &bin_attr_rw_nvmem,
 113         NULL,
 114 };
 115
 116 static const struct attribute_group nvmem_bin_rw_group = {
 117         .bin_attrs      = nvmem_bin_rw_attributes,
 118         .attrs          = nvmem_attrs,
 119 };
 120
 121 static const struct attribute_group *nvmem_rw_dev_groups[] = {
 122         &nvmem_bin_rw_group,
 123         NULL,
 124 };
 125
 126 /* read only permission */
 127 static struct bin_attribute bin_attr_ro_nvmem = {
 128         .attr   = {
 129                 .name   = "nvmem",
 130                 .mode   = 0444,
 131         },
 132         .read   = bin_attr_nvmem_read,
 133 };
 134
 135 static struct bin_attribute *nvmem_bin_ro_attributes[] = {
 136         &bin_attr_ro_nvmem,
 137         NULL,
 138 };
 139
 140 static const struct attribute_group nvmem_bin_ro_group = {
 141         .bin_attrs      = nvmem_bin_ro_attributes,
 142         .attrs          = nvmem_attrs,
 143 };
 144
 145 static const struct attribute_group *nvmem_ro_dev_groups[] = {
 146         &nvmem_bin_ro_group,
 147         NULL,
 148 };
 149
 150 /* default read/write permissions, root only */
 151 static struct bin_attribute bin_attr_rw_root_nvmem = {
 152         .attr   = {
 153                 .name   = "nvmem",
 154                 .mode   = 0600,
 155         },
 156         .read   = bin_attr_nvmem_read,
 157         .write  = bin_attr_nvmem_write,
 158 };
 159
 160 static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
 161         &bin_attr_rw_root_nvmem,
 162         NULL,
 163 };
 164
 165 static const struct attribute_group nvmem_bin_rw_root_group = {
 166         .bin_attrs      = nvmem_bin_rw_root_attributes,
 167         .attrs          = nvmem_attrs,
 168 };
 169
 170 static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
 171         &nvmem_bin_rw_root_group,
 172         NULL,
 173 };
 174
 175 /* read only permission, root only */
 176 static struct bin_attribute bin_attr_ro_root_nvmem = {
 177         .attr   = {
 178                 .name   = "nvmem",
 179                 .mode   = 0400,
 180         },
 181         .read   = bin_attr_nvmem_read,
 182 };
 183
 184 static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
 185         &bin_attr_ro_root_nvmem,
 186         NULL,
 187 };
 188
 189 static const struct attribute_group nvmem_bin_ro_root_group = {
 190         .bin_attrs      = nvmem_bin_ro_root_attributes,
 191         .attrs          = nvmem_attrs,
 192 };
 193
 194 static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
 195         &nvmem_bin_ro_root_group,
 196         NULL,
 197 };
 198
 199 const struct attribute_group **nvmem_sysfs_get_groups(
 200                                         struct nvmem_device *nvmem,
 201                                         const struct nvmem_config *config)
 202 {
 203         if (config->root_only)
 204                 return nvmem->read_only ?
 205                         nvmem_ro_root_dev_groups :
 206                         nvmem_rw_root_dev_groups;
 207
 208         return nvmem->read_only ? nvmem_ro_dev_groups : nvmem_rw_dev_groups;
 209 }
 210
 211 /*
 212  * nvmem_setup_compat() - Create an additional binary entry in
 213  * drivers sys directory, to be backwards compatible with the older
 214  * drivers/misc/eeprom drivers.
 215  */
 216 int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 217                               const struct nvmem_config *config)
 218 {
 219         int rval;
 220
 221         if (!config->compat)
 222                 return 0;
 223
 224         if (!config->base_dev)
 225                 return -EINVAL;
 226
 227         if (nvmem->read_only)
 228                 nvmem->eeprom = bin_attr_ro_root_nvmem;
 229         else
 230                 nvmem->eeprom = bin_attr_rw_root_nvmem;
 231         nvmem->eeprom.attr.name = "eeprom";
 232         nvmem->eeprom.size = nvmem->size;
 233 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 234         nvmem->eeprom.attr.key = &eeprom_lock_key;
 235 #endif
 236         nvmem->eeprom.private = &nvmem->dev;
 237         nvmem->base_dev = config->base_dev;
 238
 239         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 240         if (rval) {
 241                 dev_err(&nvmem->dev,
 242                         "Failed to create eeprom binary file %d\n", rval);
 243                 return rval;
 244         }
 245
 246         nvmem->flags |= FLAG_COMPAT;
 247
 248         return 0;
 249 }
 250
 251 void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 252                               const struct nvmem_config *config)
 253 {
 254         if (config->compat)
 255                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 256 }