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(base, ushort, 0);
  42 MODULE_PARM_DESC(base, "Base I/O address");
  43
  44 static int irq;
  45 module_param(irq, int, 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         .alert_edge_triggered   = 1,
 127 };
 128 static struct i2c_client *ara;
 129 static struct lineop parport_ctrl_irq = {
 130         .val            = (1 << 4),
 131         .port           = PORT_CTRL,
 132 };
 133
 134 static int i2c_parport_probe(struct platform_device *pdev)
 135 {
 136         int err;
 137
 138         /* Reset hardware to a sane state (SCL and SDA high) */
 139         parport_setsda(NULL, 1);
 140         parport_setscl(NULL, 1);
 141         /* Other init if needed (power on...) */
 142         if (adapter_parm[type].init.val) {
 143                 line_set(1, &adapter_parm[type].init);
 144                 /* Give powered devices some time to settle */
 145                 msleep(100);
 146         }
 147
 148         parport_adapter.dev.parent = &pdev->dev;
 149         err = i2c_bit_add_bus(&parport_adapter);
 150         if (err) {
 151                 dev_err(&pdev->dev, "Unable to register with I2C\n");
 152                 return err;
 153         }
 154
 155         /* Setup SMBus alert if supported */
 156         if (adapter_parm[type].smbus_alert && irq) {
 157                 alert_data.irq = irq;
 158                 ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
 159                 if (ara)
 160                         line_set(1, &parport_ctrl_irq);
 161                 else
 162                         dev_warn(&pdev->dev, "Failed to register ARA client\n");
 163         }
 164
 165         return 0;
 166 }
 167
 168 static int i2c_parport_remove(struct platform_device *pdev)
 169 {
 170         if (ara) {
 171                 line_set(0, &parport_ctrl_irq);
 172                 i2c_unregister_device(ara);
 173                 ara = NULL;
 174         }
 175         i2c_del_adapter(&parport_adapter);
 176
 177         /* Un-init if needed (power off...) */
 178         if (adapter_parm[type].init.val)
 179                 line_set(0, &adapter_parm[type].init);
 180
 181         return 0;
 182 }
 183
 184 static struct platform_driver i2c_parport_driver = {
 185         .driver = {
 186                 .name   = DRVNAME,
 187         },
 188         .probe          = i2c_parport_probe,
 189         .remove         = i2c_parport_remove,
 190 };
 191
 192 static int __init i2c_parport_device_add(u16 address)
 193 {
 194         int err;
 195
 196         pdev = platform_device_alloc(DRVNAME, -1);
 197         if (!pdev) {
 198                 err = -ENOMEM;
 199                 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
 200                 goto exit;
 201         }
 202
 203         err = platform_device_add(pdev);
 204         if (err) {
 205                 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
 206                        err);
 207                 goto exit_device_put;
 208         }
 209
 210         return 0;
 211
 212 exit_device_put:
 213         platform_device_put(pdev);
 214 exit:
 215         return err;
 216 }
 217
 218 static int __init i2c_parport_init(void)
 219 {
 220         int err;
 221
 222         if (type < 0) {
 223                 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
 224                 return -ENODEV;
 225         }
 226
 227         if (type >= ARRAY_SIZE(adapter_parm)) {
 228                 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
 229                 return -ENODEV;
 230         }
 231
 232         if (base == 0) {
 233                 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
 234                 base = DEFAULT_BASE;
 235         }
 236
 237         if (!request_region(base, 3, DRVNAME))
 238                 return -EBUSY;
 239
 240         if (irq != 0)
 241                 pr_info(DRVNAME ": using irq %d\n", irq);
 242
 243         if (!adapter_parm[type].getscl.val)
 244                 parport_algo_data.getscl = NULL;
 245
 246         /* Sets global pdev as a side effect */
 247         err = i2c_parport_device_add(base);
 248         if (err)
 249                 goto exit_release;
 250
 251         err = platform_driver_register(&i2c_parport_driver);
 252         if (err)
 253                 goto exit_device;
 254
 255         return 0;
 256
 257 exit_device:
 258         platform_device_unregister(pdev);
 259 exit_release:
 260         release_region(base, 3);
 261         return err;
 262 }
 263
 264 static void __exit i2c_parport_exit(void)
 265 {
 266         platform_driver_unregister(&i2c_parport_driver);
 267         platform_device_unregister(pdev);
 268         release_region(base, 3);
 269 }
 270
 271 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 272 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
 273 MODULE_LICENSE("GPL");
 274
 275 module_init(i2c_parport_init);
 276 module_exit(i2c_parport_exit);