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 #include <linux/completion.h>
  43
  44 /* Exported by i2c-core for i2c-isa only */
  45 extern void i2c_adapter_dev_release(struct device *dev);
  46 extern struct class i2c_adapter_class;
  47
  48 static u32 isa_func(struct i2c_adapter *adapter);
  49
  50 /* This is the actual algorithm we define */
  51 static const struct i2c_algorithm isa_algorithm = {
  52         .functionality  = isa_func,
  53 };
  54
  55 /* There can only be one... */
  56 static struct i2c_adapter isa_adapter = {
  57         .owner          = THIS_MODULE,
  58         .id             = I2C_HW_ISA,
  59         .class          = I2C_CLASS_HWMON,
  60         .algo           = &isa_algorithm,
  61         .name           = "ISA main adapter",
  62 };
  63
  64 /* We can't do a thing... */
  65 static u32 isa_func(struct i2c_adapter *adapter)
  66 {
  67         return 0;
  68 }
  69
  70
  71 /* We implement an interface which resembles i2c_{add,del}_driver,
  72    but for i2c-isa drivers. We don't have to remember and handle lists
  73    of drivers and adapters so this is much more simple, of course. */
  74
  75 int i2c_isa_add_driver(struct i2c_driver *driver)
  76 {
  77         int res;
  78
  79         /* Add the driver to the list of i2c drivers in the driver core */
  80         driver->driver.bus = &i2c_bus_type;
  81         res = driver_register(&driver->driver);
  82         if (res)
  83                 return res;
  84         dev_dbg(&isa_adapter.dev, "Driver %s registered\n", driver->driver.name);
  85
  86         /* Now look for clients */
  87         res = driver->attach_adapter(&isa_adapter);
  88         if (res) {
  89                 dev_dbg(&isa_adapter.dev,
  90                         "Driver %s failed to attach adapter, unregistering\n",
  91                         driver->driver.name);
  92                 driver_unregister(&driver->driver);
  93         }
  94         return res;
  95 }
  96
  97 int i2c_isa_del_driver(struct i2c_driver *driver)
  98 {
  99         struct list_head *item, *_n;
 100         struct i2c_client *client;
 101         int res;
 102
 103         /* Detach all clients belonging to this one driver */
 104         list_for_each_safe(item, _n, &isa_adapter.clients) {
 105                 client = list_entry(item, struct i2c_client, list);
 106                 if (client->driver != driver)
 107                         continue;
 108                 dev_dbg(&isa_adapter.dev, "Detaching client %s at 0x%x\n",
 109                         client->name, client->addr);
 110                 if ((res = driver->detach_client(client))) {
 111                         dev_err(&isa_adapter.dev, "Failed, driver "
 112                                 "%s not unregistered!\n",
 113                                 driver->driver.name);
 114                         return res;
 115                 }
 116         }
 117
 118         /* Get the driver off the core list */
 119         driver_unregister(&driver->driver);
 120         dev_dbg(&isa_adapter.dev, "Driver %s unregistered\n", driver->driver.name);
 121
 122         return 0;
 123 }
 124
 125
 126 static int __init i2c_isa_init(void)
 127 {
 128         int err;
 129
 130         mutex_init(&isa_adapter.clist_lock);
 131         INIT_LIST_HEAD(&isa_adapter.clients);
 132
 133         isa_adapter.nr = ANY_I2C_ISA_BUS;
 134         isa_adapter.dev.parent = &platform_bus;
 135         sprintf(isa_adapter.dev.bus_id, "i2c-%d", isa_adapter.nr);
 136         isa_adapter.dev.release = &i2c_adapter_dev_release;
 137         isa_adapter.dev.class = &i2c_adapter_class;
 138         err = device_register(&isa_adapter.dev);
 139         if (err) {
 140                 printk(KERN_ERR "i2c-isa: Failed to register device\n");
 141                 goto exit;
 142         }
 143
 144         dev_dbg(&isa_adapter.dev, "%s registered\n", isa_adapter.name);
 145
 146         return 0;
 147
 148 exit:
 149         return err;
 150 }
 151
 152 static void __exit i2c_isa_exit(void)
 153 {
 154 #ifdef DEBUG
 155         struct list_head  *item, *_n;
 156         struct i2c_client *client = NULL;
 157 #endif
 158
 159         /* There should be no more active client */
 160 #ifdef DEBUG
 161         dev_dbg(&isa_adapter.dev, "Looking for clients\n");
 162         list_for_each_safe(item, _n, &isa_adapter.clients) {
 163                 client = list_entry(item, struct i2c_client, list);
 164                 dev_err(&isa_adapter.dev, "Driver %s still has an active "
 165                         "ISA client at 0x%x\n", client->driver->driver.name,
 166                         client->addr);
 167         }
 168         if (client != NULL)
 169                 return;
 170 #endif
 171
 172         /* Clean up the sysfs representation */
 173         dev_dbg(&isa_adapter.dev, "Unregistering from sysfs\n");
 174         init_completion(&isa_adapter.dev_released);
 175         device_unregister(&isa_adapter.dev);
 176
 177         /* Wait for sysfs to drop all references */
 178         dev_dbg(&isa_adapter.dev, "Waiting for sysfs completion\n");
 179         wait_for_completion(&isa_adapter.dev_released);
 180
 181         dev_dbg(&isa_adapter.dev, "%s unregistered\n", isa_adapter.name);
 182 }
 183
 184 EXPORT_SYMBOL(i2c_isa_add_driver);
 185 EXPORT_SYMBOL(i2c_isa_del_driver);
 186
 187 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 188 MODULE_DESCRIPTION("ISA bus access through i2c");
 189 MODULE_LICENSE("GPL");
 190
 191 module_init(i2c_isa_init);
 192 module_exit(i2c_isa_exit);