drivers/base/soc.c

   1 /*
   2  * Copyright (C) ST-Ericsson SA 2011
   3  *
   4  * Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.
   5  * License terms:  GNU General Public License (GPL), version 2
   6  */
   7
   8 #include <linux/sysfs.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/stat.h>
  12 #include <linux/slab.h>
  13 #include <linux/idr.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/sys_soc.h>
  16 #include <linux/err.h>
  17
  18 static DEFINE_IDA(soc_ida);
  19 static DEFINE_SPINLOCK(soc_lock);
  20
  21 static ssize_t soc_info_get(struct device *dev,
  22                             struct device_attribute *attr,
  23                             char *buf);
  24
  25 struct soc_device {
  26         struct device dev;
  27         struct soc_device_attribute *attr;
  28         int soc_dev_num;
  29 };
  30
  31 static struct bus_type soc_bus_type = {
  32         .name  = "soc",
  33 };
  34
  35 static DEVICE_ATTR(machine,  S_IRUGO, soc_info_get,  NULL);
  36 static DEVICE_ATTR(family,   S_IRUGO, soc_info_get,  NULL);
  37 static DEVICE_ATTR(soc_id,   S_IRUGO, soc_info_get,  NULL);
  38 static DEVICE_ATTR(revision, S_IRUGO, soc_info_get,  NULL);
  39
  40 struct device *soc_device_to_device(struct soc_device *soc_dev)
  41 {
  42         return &soc_dev->dev;
  43 }
  44
  45 static mode_t soc_attribute_mode(struct kobject *kobj,
  46                                  struct attribute *attr,
  47                                  int index)
  48 {
  49         struct device *dev = container_of(kobj, struct device, kobj);
  50         struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
  51
  52         if ((attr == &dev_attr_machine.attr)
  53             && (soc_dev->attr->machine != NULL))
  54                 return attr->mode;
  55         if ((attr == &dev_attr_family.attr)
  56             && (soc_dev->attr->family != NULL))
  57                 return attr->mode;
  58         if ((attr == &dev_attr_revision.attr)
  59             && (soc_dev->attr->revision != NULL))
  60                 return attr->mode;
  61         if ((attr == &dev_attr_soc_id.attr)
  62             && (soc_dev->attr->soc_id != NULL))
  63                 return attr->mode;
  64
  65         /* Unknown or unfilled attribute. */
  66         return 0;
  67 }
  68
  69 static ssize_t soc_info_get(struct device *dev,
  70                             struct device_attribute *attr,
  71                             char *buf)
  72 {
  73         struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
  74
  75         if (attr == &dev_attr_machine)
  76                 return sprintf(buf, "%s\n", soc_dev->attr->machine);
  77         if (attr == &dev_attr_family)
  78                 return sprintf(buf, "%s\n", soc_dev->attr->family);
  79         if (attr == &dev_attr_revision)
  80                 return sprintf(buf, "%s\n", soc_dev->attr->revision);
  81         if (attr == &dev_attr_soc_id)
  82                 return sprintf(buf, "%s\n", soc_dev->attr->soc_id);
  83
  84         return -EINVAL;
  85
  86 }
  87
  88 static struct attribute *soc_attr[] = {
  89         &dev_attr_machine.attr,
  90         &dev_attr_family.attr,
  91         &dev_attr_soc_id.attr,
  92         &dev_attr_revision.attr,
  93         NULL,
  94 };
  95
  96 static const struct attribute_group soc_attr_group = {
  97         .attrs = soc_attr,
  98         .is_visible = soc_attribute_mode,
  99 };
 100
 101 static const struct attribute_group *soc_attr_groups[] = {
 102         &soc_attr_group,
 103         NULL,
 104 };
 105
 106 static void soc_release(struct device *dev)
 107 {
 108         struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
 109
 110         kfree(soc_dev);
 111 }
 112
 113 struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
 114 {
 115         struct soc_device *soc_dev;
 116         int ret;
 117
 118         soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);
 119         if (!soc_dev) {
 120                 ret = -ENOMEM;
 121                 goto out1;
 122         }
 123
 124         /* Fetch a unique (reclaimable) SOC ID. */
 125         do {
 126                 if (!ida_pre_get(&soc_ida, GFP_KERNEL)) {
 127                         ret = -ENOMEM;
 128                         goto out2;
 129                 }
 130
 131                 spin_lock(&soc_lock);
 132                 ret = ida_get_new(&soc_ida, &soc_dev->soc_dev_num);
 133                 spin_unlock(&soc_lock);
 134
 135         } while (ret == -EAGAIN);
 136
 137         if (ret)
 138                  goto out2;
 139
 140         soc_dev->attr = soc_dev_attr;
 141         soc_dev->dev.bus = &soc_bus_type;
 142         soc_dev->dev.groups = soc_attr_groups;
 143         soc_dev->dev.release = soc_release;
 144
 145         dev_set_name(&soc_dev->dev, "soc%d", soc_dev->soc_dev_num);
 146
 147         ret = device_register(&soc_dev->dev);
 148         if (ret)
 149                 goto out3;
 150
 151         return soc_dev;
 152
 153 out3:
 154         ida_remove(&soc_ida, soc_dev->soc_dev_num);
 155 out2:
 156         kfree(soc_dev);
 157 out1:
 158         return ERR_PTR(ret);
 159 }
 160
 161 /* Ensure soc_dev->attr is freed prior to calling soc_device_unregister. */
 162 void soc_device_unregister(struct soc_device *soc_dev)
 163 {
 164         ida_remove(&soc_ida, soc_dev->soc_dev_num);
 165
 166         device_unregister(&soc_dev->dev);
 167 }
 168
 169 static int __init soc_bus_register(void)
 170 {
 171         return bus_register(&soc_bus_type);
 172 }
 173 core_initcall(soc_bus_register);
 174
 175 static void __exit soc_bus_unregister(void)
 176 {
 177         ida_destroy(&soc_ida);
 178
 179         bus_unregister(&soc_bus_type);
 180 }
 181 module_exit(soc_bus_unregister);