drivers/i2c/busses/i2c-isa.c

   1 /*
   2     i2c-isa.c - an i2c-core-like thing for ISA hardware monitoring chips
   3     Copyright (C) 2005  Jean Delvare <khali@linux-fr.org>
   4
   5     Based on the i2c-isa pseudo-adapter from the lm_sensors project
   6     Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 /* This implements an i2c-core-like thing for ISA hardware monitoring
  24    chips. Such chips are linked to the i2c subsystem for historical
  25    reasons (because the early ISA hardware monitoring chips such as the
  26    LM78 had both an I2C and an ISA interface). They used to be
  27    registered with the main i2c-core, but as a first step in the
  28    direction of a clean separation between I2C and ISA chip drivers,
  29    we now have this separate core for ISA ones. It is significantly
  30    more simple than the real one, of course, because we don't have to
  31    handle multiple busses: there is only one (fake) ISA adapter.
  32    It is worth noting that we still rely on i2c-core for some things
  33    at the moment - but hopefully this won't last. */
  34
  35 #include <linux/init.h>
  36 #include <linux/module.h>
  37 #include <linux/kernel.h>
  38 #include <linux/errno.h>
  39 #include <linux/i2c.h>
  40 #include <linux/i2c-isa.h>
  41 #include <linux/platform_device.h>
  42
  43 static u32 isa_func(struct i2c_adapter *adapter);
  44
  45 /* This is the actual algorithm we define */
  46 static const struct i2c_algorithm isa_algorithm = {
  47         .functionality  = isa_func,
  48 };
  49
  50 /* There can only be one... */
  51 static struct i2c_adapter isa_adapter = {
  52         .owner          = THIS_MODULE,
  53         .id             = I2C_HW_ISA,
  54         .class          = I2C_CLASS_HWMON,
  55         .algo           = &isa_algorithm,
  56         .name           = "ISA main adapter",
  57 };
  58
  59 /* We can't do a thing... */
  60 static u32 isa_func(struct i2c_adapter *adapter)
  61 {
  62         return 0;
  63 }
  64
  65
  66 /* Copied from i2c-core */
  67 static ssize_t show_adapter_name(struct device *dev,
  68                 struct device_attribute *attr, char *buf)
  69 {
  70         struct i2c_adapter *adap = dev_to_i2c_adapter(dev);
  71         return sprintf(buf, "%s\n", adap->name);
  72 }
  73 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
  74
  75
  76 /* We implement an interface which resembles i2c_{add,del}_driver,
  77    but for i2c-isa drivers. We don't have to remember and handle lists
  78    of drivers and adapters so this is much more simple, of course. */
  79
  80 int i2c_isa_add_driver(struct i2c_driver *driver)
  81 {
  82         int res;
  83
  84         /* Add the driver to the list of i2c drivers in the driver core */
  85         driver->driver.bus = &i2c_bus_type;
  86         res = driver_register(&driver->driver);
  87         if (res)
  88                 return res;
  89         dev_dbg(&isa_adapter.dev, "Driver %s registered\n", driver->driver.name);
  90
  91         /* Now look for clients */
  92         res = driver->attach_adapter(&isa_adapter);
  93         if (res) {
  94                 dev_dbg(&isa_adapter.dev,
  95                         "Driver %s failed to attach adapter, unregistering\n",
  96                         driver->driver.name);
  97                 driver_unregister(&driver->driver);
  98         }
  99         return res;
 100 }
 101
 102 int i2c_isa_del_driver(struct i2c_driver *driver)
 103 {
 104         struct list_head *item, *_n;
 105         struct i2c_client *client;
 106         int res;
 107
 108         /* Detach all clients belonging to this one driver */
 109         list_for_each_safe(item, _n, &isa_adapter.clients) {
 110                 client = list_entry(item, struct i2c_client, list);
 111                 if (client->driver != driver)
 112                         continue;
 113                 dev_dbg(&isa_adapter.dev, "Detaching client %s at 0x%x\n",
 114                         client->name, client->addr);
 115                 if ((res = driver->detach_client(client))) {
 116                         dev_err(&isa_adapter.dev, "Failed, driver "
 117                                 "%s not unregistered!\n",
 118                                 driver->driver.name);
 119                         return res;
 120                 }
 121         }
 122
 123         /* Get the driver off the core list */
 124         driver_unregister(&driver->driver);
 125         dev_dbg(&isa_adapter.dev, "Driver %s unregistered\n", driver->driver.name);
 126
 127         return 0;
 128 }
 129
 130
 131 static int __init i2c_isa_init(void)
 132 {
 133         int err;
 134
 135         mutex_init(&isa_adapter.clist_lock);
 136         INIT_LIST_HEAD(&isa_adapter.clients);
 137
 138         isa_adapter.nr = ANY_I2C_ISA_BUS;
 139         isa_adapter.dev.parent = &platform_bus;
 140         sprintf(isa_adapter.dev.bus_id, "i2c-%d", isa_adapter.nr);
 141         isa_adapter.dev.driver = &i2c_adapter_driver;
 142         isa_adapter.dev.release = &i2c_adapter_dev_release;
 143         err = device_register(&isa_adapter.dev);
 144         if (err) {
 145                 printk(KERN_ERR "i2c-isa: Failed to register device\n");
 146                 goto exit;
 147         }
 148         err = device_create_file(&isa_adapter.dev, &dev_attr_name);
 149         if (err) {
 150                 printk(KERN_ERR "i2c-isa: Failed to create name file\n");
 151                 goto exit_unregister;
 152         }
 153
 154         /* Add this adapter to the i2c_adapter class */
 155         memset(&isa_adapter.class_dev, 0x00, sizeof(struct class_device));
 156         isa_adapter.class_dev.dev = &isa_adapter.dev;
 157         isa_adapter.class_dev.class = &i2c_adapter_class;
 158         strlcpy(isa_adapter.class_dev.class_id, isa_adapter.dev.bus_id,
 159                 BUS_ID_SIZE);
 160         err = class_device_register(&isa_adapter.class_dev);
 161         if (err) {
 162                 printk(KERN_ERR "i2c-isa: Failed to register class device\n");
 163                 goto exit_remove_name;
 164         }
 165
 166         dev_dbg(&isa_adapter.dev, "%s registered\n", isa_adapter.name);
 167
 168         return 0;
 169
 170 exit_remove_name:
 171         device_remove_file(&isa_adapter.dev, &dev_attr_name);
 172 exit_unregister:
 173         init_completion(&isa_adapter.dev_released); /* Needed? */
 174         device_unregister(&isa_adapter.dev);
 175         wait_for_completion(&isa_adapter.dev_released);
 176 exit:
 177         return err;
 178 }
 179
 180 static void __exit i2c_isa_exit(void)
 181 {
 182 #ifdef DEBUG
 183         struct list_head  *item, *_n;
 184         struct i2c_client *client = NULL;
 185 #endif
 186
 187         /* There should be no more active client */
 188 #ifdef DEBUG
 189         dev_dbg(&isa_adapter.dev, "Looking for clients\n");
 190         list_for_each_safe(item, _n, &isa_adapter.clients) {
 191                 client = list_entry(item, struct i2c_client, list);
 192                 dev_err(&isa_adapter.dev, "Driver %s still has an active "
 193                         "ISA client at 0x%x\n", client->driver->driver.name,
 194                         client->addr);
 195         }
 196         if (client != NULL)
 197                 return;
 198 #endif
 199
 200         /* Clean up the sysfs representation */
 201         dev_dbg(&isa_adapter.dev, "Unregistering from sysfs\n");
 202         init_completion(&isa_adapter.dev_released);
 203         init_completion(&isa_adapter.class_dev_released);
 204         class_device_unregister(&isa_adapter.class_dev);
 205         device_remove_file(&isa_adapter.dev, &dev_attr_name);
 206         device_unregister(&isa_adapter.dev);
 207
 208         /* Wait for sysfs to drop all references */
 209         dev_dbg(&isa_adapter.dev, "Waiting for sysfs completion\n");
 210         wait_for_completion(&isa_adapter.dev_released);
 211         wait_for_completion(&isa_adapter.class_dev_released);
 212
 213         dev_dbg(&isa_adapter.dev, "%s unregistered\n", isa_adapter.name);
 214 }
 215
 216 EXPORT_SYMBOL(i2c_isa_add_driver);
 217 EXPORT_SYMBOL(i2c_isa_del_driver);
 218
 219 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 220 MODULE_DESCRIPTION("ISA bus access through i2c");
 221 MODULE_LICENSE("GPL");
 222
 223 module_init(i2c_isa_init);
 224 module_exit(i2c_isa_exit);