drivers/i2c/busses/i2c-parport-light.c

   1 /* ------------------------------------------------------------------------ *
   2  * i2c-parport-light.c I2C bus over parallel port                           *
   3  * ------------------------------------------------------------------------ *
   4    Copyright (C) 2003-2010 Jean Delvare <jdelvare@suse.de>
   5
   6    Based on older i2c-velleman.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
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/delay.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/ioport.h>
  29 #include <linux/i2c.h>
  30 #include <linux/i2c-algo-bit.h>
  31 #include <linux/i2c-smbus.h>
  32 #include <linux/io.h>
  33 #include "i2c-parport.h"
  34
  35 #define DEFAULT_BASE 0x378
  36 #define DRVNAME "i2c-parport-light"
  37
  38 static struct platform_device *pdev;
  39
  40 static u16 base;
  41 module_param_hw(base, ushort, ioport, 0);
  42 MODULE_PARM_DESC(base, "Base I/O address");
  43
  44 static int irq;
  45 module_param_hw(irq, int, irq, 0);
  46 MODULE_PARM_DESC(irq, "IRQ (optional)");
  47
  48 /* ----- Low-level parallel port access ----------------------------------- */
  49
  50 static inline void port_write(unsigned char p, unsigned char d)
  51 {
  52         outb(d, base+p);
  53 }
  54
  55 static inline unsigned char port_read(unsigned char p)
  56 {
  57         return inb(base+p);
  58 }
  59
  60 /* ----- Unified line operation functions --------------------------------- */
  61
  62 static inline void line_set(int state, const struct lineop *op)
  63 {
  64         u8 oldval = port_read(op->port);
  65
  66         /* Touch only the bit(s) needed */
  67         if ((op->inverted && !state) || (!op->inverted && state))
  68                 port_write(op->port, oldval | op->val);
  69         else
  70                 port_write(op->port, oldval & ~op->val);
  71 }
  72
  73 static inline int line_get(const struct lineop *op)
  74 {
  75         u8 oldval = port_read(op->port);
  76
  77         return ((op->inverted && (oldval & op->val) != op->val)
  78             || (!op->inverted && (oldval & op->val) == op->val));
  79 }
  80
  81 /* ----- I2C algorithm call-back functions and structures ----------------- */
  82
  83 static void parport_setscl(void *data, int state)
  84 {
  85         line_set(state, &adapter_parm[type].setscl);
  86 }
  87
  88 static void parport_setsda(void *data, int state)
  89 {
  90         line_set(state, &adapter_parm[type].setsda);
  91 }
  92
  93 static int parport_getscl(void *data)
  94 {
  95         return line_get(&adapter_parm[type].getscl);
  96 }
  97
  98 static int parport_getsda(void *data)
  99 {
 100         return line_get(&adapter_parm[type].getsda);
 101 }
 102
 103 /* Encapsulate the functions above in the correct structure
 104    Note that getscl will be set to NULL by the attaching code for adapters
 105    that cannot read SCL back */
 106 static struct i2c_algo_bit_data parport_algo_data = {
 107         .setsda         = parport_setsda,
 108         .setscl         = parport_setscl,
 109         .getsda         = parport_getsda,
 110         .getscl         = parport_getscl,
 111         .udelay         = 50,
 112         .timeout        = HZ,
 113 };
 114
 115 /* ----- Driver registration ---------------------------------------------- */
 116
 117 static struct i2c_adapter parport_adapter = {
 118         .owner          = THIS_MODULE,
 119         .class          = I2C_CLASS_HWMON,
 120         .algo_data      = &parport_algo_data,
 121         .name           = "Parallel port adapter (light)",
 122 };
 123
 124 /* SMBus alert support */
 125 static struct i2c_smbus_alert_setup alert_data = {
 126 };
 127 static struct i2c_client *ara;
 128 static struct lineop parport_ctrl_irq = {
 129         .val            = (1 << 4),
 130         .port           = PORT_CTRL,
 131 };
 132
 133 static int i2c_parport_probe(struct platform_device *pdev)
 134 {
 135         int err;
 136
 137         /* Reset hardware to a sane state (SCL and SDA high) */
 138         parport_setsda(NULL, 1);
 139         parport_setscl(NULL, 1);
 140         /* Other init if needed (power on...) */
 141         if (adapter_parm[type].init.val) {
 142                 line_set(1, &adapter_parm[type].init);
 143                 /* Give powered devices some time to settle */
 144                 msleep(100);
 145         }
 146
 147         parport_adapter.dev.parent = &pdev->dev;
 148         err = i2c_bit_add_bus(&parport_adapter);
 149         if (err) {
 150                 dev_err(&pdev->dev, "Unable to register with I2C\n");
 151                 return err;
 152         }
 153
 154         /* Setup SMBus alert if supported */
 155         if (adapter_parm[type].smbus_alert && irq) {
 156                 alert_data.irq = irq;
 157                 ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
 158                 if (ara)
 159                         line_set(1, &parport_ctrl_irq);
 160                 else
 161                         dev_warn(&pdev->dev, "Failed to register ARA client\n");
 162         }
 163
 164         return 0;
 165 }
 166
 167 static int i2c_parport_remove(struct platform_device *pdev)
 168 {
 169         if (ara) {
 170                 line_set(0, &parport_ctrl_irq);
 171                 i2c_unregister_device(ara);
 172                 ara = NULL;
 173         }
 174         i2c_del_adapter(&parport_adapter);
 175
 176         /* Un-init if needed (power off...) */
 177         if (adapter_parm[type].init.val)
 178                 line_set(0, &adapter_parm[type].init);
 179
 180         return 0;
 181 }
 182
 183 static struct platform_driver i2c_parport_driver = {
 184         .driver = {
 185                 .name   = DRVNAME,
 186         },
 187         .probe          = i2c_parport_probe,
 188         .remove         = i2c_parport_remove,
 189 };
 190
 191 static int __init i2c_parport_device_add(u16 address)
 192 {
 193         int err;
 194
 195         pdev = platform_device_alloc(DRVNAME, -1);
 196         if (!pdev) {
 197                 err = -ENOMEM;
 198                 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
 199                 goto exit;
 200         }
 201
 202         err = platform_device_add(pdev);
 203         if (err) {
 204                 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
 205                        err);
 206                 goto exit_device_put;
 207         }
 208
 209         return 0;
 210
 211 exit_device_put:
 212         platform_device_put(pdev);
 213 exit:
 214         return err;
 215 }
 216
 217 static int __init i2c_parport_init(void)
 218 {
 219         int err;
 220
 221         if (type < 0) {
 222                 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
 223                 return -ENODEV;
 224         }
 225
 226         if (type >= ARRAY_SIZE(adapter_parm)) {
 227                 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
 228                 return -ENODEV;
 229         }
 230
 231         if (base == 0) {
 232                 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
 233                 base = DEFAULT_BASE;
 234         }
 235
 236         if (!request_region(base, 3, DRVNAME))
 237                 return -EBUSY;
 238
 239         if (irq != 0)
 240                 pr_info(DRVNAME ": using irq %d\n", irq);
 241
 242         if (!adapter_parm[type].getscl.val)
 243                 parport_algo_data.getscl = NULL;
 244
 245         /* Sets global pdev as a side effect */
 246         err = i2c_parport_device_add(base);
 247         if (err)
 248                 goto exit_release;
 249
 250         err = platform_driver_register(&i2c_parport_driver);
 251         if (err)
 252                 goto exit_device;
 253
 254         return 0;
 255
 256 exit_device:
 257         platform_device_unregister(pdev);
 258 exit_release:
 259         release_region(base, 3);
 260         return err;
 261 }
 262
 263 static void __exit i2c_parport_exit(void)
 264 {
 265         platform_driver_unregister(&i2c_parport_driver);
 266         platform_device_unregister(pdev);
 267         release_region(base, 3);
 268 }
 269
 270 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 271 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
 272 MODULE_LICENSE("GPL");
 273
 274 module_init(i2c_parport_init);
 275 module_exit(i2c_parport_exit);