drivers/i2c/busses/i2c-parport.c

   1 /* ------------------------------------------------------------------------ *
   2  * i2c-parport.c I2C bus over parallel port                                 *
   3  * ------------------------------------------------------------------------ *
   4    Copyright (C) 2003-2011 Jean Delvare <khali@linux-fr.org>
   5
   6    Based on older i2c-philips-par.c driver
   7    Copyright (C) 1995-2000 Simon G. Vogl
   8    With some changes from:
   9    Frodo Looijaard <frodol@dds.nl>
  10    Kyösti Mälkki <kmalkki@cc.hut.fi>
  11
  12    This program is free software; you can redistribute it and/or modify
  13    it under the terms of the GNU General Public License as published by
  14    the Free Software Foundation; either version 2 of the License, or
  15    (at your option) any later version.
  16
  17    This program is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20    GNU General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program; if not, write to the Free Software
  24    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  25  * ------------------------------------------------------------------------ */
  26
  27 #include <linux/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/init.h>
  30 #include <linux/delay.h>
  31 #include <linux/parport.h>
  32 #include <linux/i2c.h>
  33 #include <linux/i2c-algo-bit.h>
  34 #include <linux/i2c-smbus.h>
  35 #include <linux/slab.h>
  36 #include <linux/list.h>
  37 #include <linux/mutex.h>
  38 #include "i2c-parport.h"
  39
  40 /* ----- Device list ------------------------------------------------------ */
  41
  42 struct i2c_par {
  43         struct pardevice *pdev;
  44         struct i2c_adapter adapter;
  45         struct i2c_algo_bit_data algo_data;
  46         struct i2c_smbus_alert_setup alert_data;
  47         struct i2c_client *ara;
  48         struct list_head node;
  49 };
  50
  51 static LIST_HEAD(adapter_list);
  52 static DEFINE_MUTEX(adapter_list_lock);
  53
  54 /* ----- Low-level parallel port access ----------------------------------- */
  55
  56 static void port_write_data(struct parport *p, unsigned char d)
  57 {
  58         parport_write_data(p, d);
  59 }
  60
  61 static void port_write_control(struct parport *p, unsigned char d)
  62 {
  63         parport_write_control(p, d);
  64 }
  65
  66 static unsigned char port_read_data(struct parport *p)
  67 {
  68         return parport_read_data(p);
  69 }
  70
  71 static unsigned char port_read_status(struct parport *p)
  72 {
  73         return parport_read_status(p);
  74 }
  75
  76 static unsigned char port_read_control(struct parport *p)
  77 {
  78         return parport_read_control(p);
  79 }
  80
  81 static void (* const port_write[])(struct parport *, unsigned char) = {
  82         port_write_data,
  83         NULL,
  84         port_write_control,
  85 };
  86
  87 static unsigned char (* const port_read[])(struct parport *) = {
  88         port_read_data,
  89         port_read_status,
  90         port_read_control,
  91 };
  92
  93 /* ----- Unified line operation functions --------------------------------- */
  94
  95 static inline void line_set(struct parport *data, int state,
  96         const struct lineop *op)
  97 {
  98         u8 oldval = port_read[op->port](data);
  99
 100         /* Touch only the bit(s) needed */
 101         if ((op->inverted && !state) || (!op->inverted && state))
 102                 port_write[op->port](data, oldval | op->val);
 103         else
 104                 port_write[op->port](data, oldval & ~op->val);
 105 }
 106
 107 static inline int line_get(struct parport *data,
 108         const struct lineop *op)
 109 {
 110         u8 oldval = port_read[op->port](data);
 111
 112         return ((op->inverted && (oldval & op->val) != op->val)
 113             || (!op->inverted && (oldval & op->val) == op->val));
 114 }
 115
 116 /* ----- I2C algorithm call-back functions and structures ----------------- */
 117
 118 static void parport_setscl(void *data, int state)
 119 {
 120         line_set((struct parport *) data, state, &adapter_parm[type].setscl);
 121 }
 122
 123 static void parport_setsda(void *data, int state)
 124 {
 125         line_set((struct parport *) data, state, &adapter_parm[type].setsda);
 126 }
 127
 128 static int parport_getscl(void *data)
 129 {
 130         return line_get((struct parport *) data, &adapter_parm[type].getscl);
 131 }
 132
 133 static int parport_getsda(void *data)
 134 {
 135         return line_get((struct parport *) data, &adapter_parm[type].getsda);
 136 }
 137
 138 /* Encapsulate the functions above in the correct structure.
 139    Note that this is only a template, from which the real structures are
 140    copied. The attaching code will set getscl to NULL for adapters that
 141    cannot read SCL back, and will also make the data field point to
 142    the parallel port structure. */
 143 static const struct i2c_algo_bit_data parport_algo_data = {
 144         .setsda         = parport_setsda,
 145         .setscl         = parport_setscl,
 146         .getsda         = parport_getsda,
 147         .getscl         = parport_getscl,
 148         .udelay         = 10, /* ~50 kbps */
 149         .timeout        = HZ,
 150 };
 151
 152 /* ----- I2c and parallel port call-back functions and structures --------- */
 153
 154 void i2c_parport_irq(void *data)
 155 {
 156         struct i2c_par *adapter = data;
 157         struct i2c_client *ara = adapter->ara;
 158
 159         if (ara) {
 160                 dev_dbg(&ara->dev, "SMBus alert received\n");
 161                 i2c_handle_smbus_alert(ara);
 162         } else
 163                 dev_dbg(&adapter->adapter.dev,
 164                         "SMBus alert received but no ARA client!\n");
 165 }
 166
 167 static void i2c_parport_attach(struct parport *port)
 168 {
 169         struct i2c_par *adapter;
 170
 171         adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
 172         if (adapter == NULL) {
 173                 printk(KERN_ERR "i2c-parport: Failed to kzalloc\n");
 174                 return;
 175         }
 176
 177         pr_debug("i2c-parport: attaching to %s\n", port->name);
 178         parport_disable_irq(port);
 179         adapter->pdev = parport_register_device(port, "i2c-parport",
 180                 NULL, NULL, i2c_parport_irq, PARPORT_FLAG_EXCL, adapter);
 181         if (!adapter->pdev) {
 182                 printk(KERN_ERR "i2c-parport: Unable to register with parport\n");
 183                 goto err_free;
 184         }
 185
 186         /* Fill the rest of the structure */
 187         adapter->adapter.owner = THIS_MODULE;
 188         adapter->adapter.class = I2C_CLASS_HWMON;
 189         strlcpy(adapter->adapter.name, "Parallel port adapter",
 190                 sizeof(adapter->adapter.name));
 191         adapter->algo_data = parport_algo_data;
 192         /* Slow down if we can't sense SCL */
 193         if (!adapter_parm[type].getscl.val) {
 194                 adapter->algo_data.getscl = NULL;
 195                 adapter->algo_data.udelay = 50; /* ~10 kbps */
 196         }
 197         adapter->algo_data.data = port;
 198         adapter->adapter.algo_data = &adapter->algo_data;
 199         adapter->adapter.dev.parent = port->physport->dev;
 200
 201         if (parport_claim_or_block(adapter->pdev) < 0) {
 202                 printk(KERN_ERR "i2c-parport: Could not claim parallel port\n");
 203                 goto err_unregister;
 204         }
 205
 206         /* Reset hardware to a sane state (SCL and SDA high) */
 207         parport_setsda(port, 1);
 208         parport_setscl(port, 1);
 209         /* Other init if needed (power on...) */
 210         if (adapter_parm[type].init.val) {
 211                 line_set(port, 1, &adapter_parm[type].init);
 212                 /* Give powered devices some time to settle */
 213                 msleep(100);
 214         }
 215
 216         if (i2c_bit_add_bus(&adapter->adapter) < 0) {
 217                 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
 218                 goto err_unregister;
 219         }
 220
 221         /* Setup SMBus alert if supported */
 222         if (adapter_parm[type].smbus_alert) {
 223                 adapter->alert_data.alert_edge_triggered = 1;
 224                 adapter->ara = i2c_setup_smbus_alert(&adapter->adapter,
 225                                                      &adapter->alert_data);
 226                 if (adapter->ara)
 227                         parport_enable_irq(port);
 228                 else
 229                         printk(KERN_WARNING "i2c-parport: Failed to register "
 230                                "ARA client\n");
 231         }
 232
 233         /* Add the new adapter to the list */
 234         mutex_lock(&adapter_list_lock);
 235         list_add_tail(&adapter->node, &adapter_list);
 236         mutex_unlock(&adapter_list_lock);
 237         return;
 238
 239  err_unregister:
 240         parport_release(adapter->pdev);
 241         parport_unregister_device(adapter->pdev);
 242  err_free:
 243         kfree(adapter);
 244 }
 245
 246 static void i2c_parport_detach(struct parport *port)
 247 {
 248         struct i2c_par *adapter, *_n;
 249
 250         /* Walk the list */
 251         mutex_lock(&adapter_list_lock);
 252         list_for_each_entry_safe(adapter, _n, &adapter_list, node) {
 253                 if (adapter->pdev->port == port) {
 254                         if (adapter->ara) {
 255                                 parport_disable_irq(port);
 256                                 i2c_unregister_device(adapter->ara);
 257                         }
 258                         i2c_del_adapter(&adapter->adapter);
 259
 260                         /* Un-init if needed (power off...) */
 261                         if (adapter_parm[type].init.val)
 262                                 line_set(port, 0, &adapter_parm[type].init);
 263
 264                         parport_release(adapter->pdev);
 265                         parport_unregister_device(adapter->pdev);
 266                         list_del(&adapter->node);
 267                         kfree(adapter);
 268                 }
 269         }
 270         mutex_unlock(&adapter_list_lock);
 271 }
 272
 273 static struct parport_driver i2c_parport_driver = {
 274         .name   = "i2c-parport",
 275         .attach = i2c_parport_attach,
 276         .detach = i2c_parport_detach,
 277 };
 278
 279 /* ----- Module loading, unloading and information ------------------------ */
 280
 281 static int __init i2c_parport_init(void)
 282 {
 283         if (type < 0) {
 284                 printk(KERN_WARNING "i2c-parport: adapter type unspecified\n");
 285                 return -ENODEV;
 286         }
 287
 288         if (type >= ARRAY_SIZE(adapter_parm)) {
 289                 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
 290                 return -ENODEV;
 291         }
 292
 293         return parport_register_driver(&i2c_parport_driver);
 294 }
 295
 296 static void __exit i2c_parport_exit(void)
 297 {
 298         parport_unregister_driver(&i2c_parport_driver);
 299 }
 300
 301 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 302 MODULE_DESCRIPTION("I2C bus over parallel port");
 303 MODULE_LICENSE("GPL");
 304
 305 module_init(i2c_parport_init);
 306 module_exit(i2c_parport_exit);