drivers/media/usb/stk1160/stk1160-i2c.c

   1 /*
   2  * STK1160 driver
   3  *
   4  * Copyright (C) 2012 Ezequiel Garcia
   5  * <elezegarcia--a.t--gmail.com>
   6  *
   7  * Based on Easycap driver by R.M. Thomas
   8  *      Copyright (C) 2010 R.M. Thomas
   9  *      <rmthomas--a.t--sciolus.org>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/usb.h>
  25 #include <linux/i2c.h>
  26
  27 #include "stk1160.h"
  28 #include "stk1160-reg.h"
  29
  30 static unsigned int i2c_debug;
  31 module_param(i2c_debug, int, 0644);
  32 MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");
  33
  34 #define dprintk_i2c(fmt, args...)                               \
  35 do {                                                            \
  36         if (i2c_debug)                                          \
  37                 printk(KERN_DEBUG fmt, ##args);                 \
  38 } while (0)
  39
  40 static int stk1160_i2c_busy_wait(struct stk1160 *dev, u8 wait_bit_mask)
  41 {
  42         unsigned long end;
  43         u8 flag;
  44
  45         /* Wait until read/write finish bit is set */
  46         end = jiffies + msecs_to_jiffies(STK1160_I2C_TIMEOUT);
  47         while (time_is_after_jiffies(end)) {
  48
  49                 stk1160_read_reg(dev, STK1160_SICTL+1, &flag);
  50                 /* read/write done? */
  51                 if (flag & wait_bit_mask)
  52                         goto done;
  53
  54                 usleep_range(10 * USEC_PER_MSEC, 20 * USEC_PER_MSEC);
  55         }
  56
  57         return -ETIMEDOUT;
  58
  59 done:
  60         return 0;
  61 }
  62
  63 static int stk1160_i2c_write_reg(struct stk1160 *dev, u8 addr,
  64                 u8 reg, u8 value)
  65 {
  66         int rc;
  67
  68         /* Set serial device address */
  69         rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
  70         if (rc < 0)
  71                 return rc;
  72
  73         /* Set i2c device register sub-address */
  74         rc = stk1160_write_reg(dev, STK1160_SBUSW_WA, reg);
  75         if (rc < 0)
  76                 return rc;
  77
  78         /* Set i2c device register value */
  79         rc = stk1160_write_reg(dev, STK1160_SBUSW_WD, value);
  80         if (rc < 0)
  81                 return rc;
  82
  83         /* Start write now */
  84         rc = stk1160_write_reg(dev, STK1160_SICTL, 0x01);
  85         if (rc < 0)
  86                 return rc;
  87
  88         rc = stk1160_i2c_busy_wait(dev, 0x04);
  89         if (rc < 0)
  90                 return rc;
  91
  92         return 0;
  93 }
  94
  95 static int stk1160_i2c_read_reg(struct stk1160 *dev, u8 addr,
  96                 u8 reg, u8 *value)
  97 {
  98         int rc;
  99
 100         /* Set serial device address */
 101         rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
 102         if (rc < 0)
 103                 return rc;
 104
 105         /* Set i2c device register sub-address */
 106         rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, reg);
 107         if (rc < 0)
 108                 return rc;
 109
 110         /* Start read now */
 111         rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
 112         if (rc < 0)
 113                 return rc;
 114
 115         rc = stk1160_i2c_busy_wait(dev, 0x01);
 116         if (rc < 0)
 117                 return rc;
 118
 119         rc = stk1160_read_reg(dev, STK1160_SBUSR_RD, value);
 120         if (rc < 0)
 121                 return rc;
 122
 123         return 0;
 124 }
 125
 126 /*
 127  * stk1160_i2c_check_for_device()
 128  * check if there is a i2c_device at the supplied address
 129  */
 130 static int stk1160_i2c_check_for_device(struct stk1160 *dev,
 131                 unsigned char addr)
 132 {
 133         int rc;
 134
 135         /* Set serial device address */
 136         rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
 137         if (rc < 0)
 138                 return rc;
 139
 140         /* Set device sub-address, we'll chip version reg */
 141         rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, 0x00);
 142         if (rc < 0)
 143                 return rc;
 144
 145         /* Start read now */
 146         rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
 147         if (rc < 0)
 148                 return rc;
 149
 150         rc = stk1160_i2c_busy_wait(dev, 0x01);
 151         if (rc < 0)
 152                 return -ENODEV;
 153
 154         return 0;
 155 }
 156
 157 /*
 158  * stk1160_i2c_xfer()
 159  * the main i2c transfer function
 160  */
 161 static int stk1160_i2c_xfer(struct i2c_adapter *i2c_adap,
 162                            struct i2c_msg msgs[], int num)
 163 {
 164         struct stk1160 *dev = i2c_adap->algo_data;
 165         int addr, rc, i;
 166
 167         for (i = 0; i < num; i++) {
 168                 addr = msgs[i].addr << 1;
 169                 dprintk_i2c("%s: addr=%x", __func__, addr);
 170
 171                 if (!msgs[i].len) {
 172                         /* no len: check only for device presence */
 173                         rc = stk1160_i2c_check_for_device(dev, addr);
 174                         if (rc < 0) {
 175                                 dprintk_i2c(" no device\n");
 176                                 return rc;
 177                         }
 178
 179                 } else if (msgs[i].flags & I2C_M_RD) {
 180                         /* read request without preceding register selection */
 181                         dprintk_i2c(" subaddr not selected");
 182                         rc = -EOPNOTSUPP;
 183                         goto err;
 184
 185                 } else if (i + 1 < num && msgs[i].len <= 2 &&
 186                            (msgs[i + 1].flags & I2C_M_RD) &&
 187                            msgs[i].addr == msgs[i + 1].addr) {
 188
 189                         if (msgs[i].len != 1 || msgs[i + 1].len != 1) {
 190                                 dprintk_i2c(" len not supported");
 191                                 rc = -EOPNOTSUPP;
 192                                 goto err;
 193                         }
 194
 195                         dprintk_i2c(" subaddr=%x", msgs[i].buf[0]);
 196
 197                         rc = stk1160_i2c_read_reg(dev, addr, msgs[i].buf[0],
 198                                 msgs[i + 1].buf);
 199
 200                         dprintk_i2c(" read=%x", *msgs[i + 1].buf);
 201
 202                         /* consumed two msgs, so we skip one of them */
 203                         i++;
 204
 205                 } else {
 206                         if (msgs[i].len != 2) {
 207                                 dprintk_i2c(" len not supported");
 208                                 rc = -EOPNOTSUPP;
 209                                 goto err;
 210                         }
 211
 212                         dprintk_i2c(" subaddr=%x write=%x",
 213                                 msgs[i].buf[0],  msgs[i].buf[1]);
 214
 215                         rc = stk1160_i2c_write_reg(dev, addr, msgs[i].buf[0],
 216                                 msgs[i].buf[1]);
 217                 }
 218
 219                 if (rc < 0)
 220                         goto err;
 221                 dprintk_i2c(" OK\n");
 222         }
 223
 224         return num;
 225 err:
 226         dprintk_i2c(" ERROR: %d\n", rc);
 227         return num;
 228 }
 229
 230 /*
 231  * functionality(), what da heck is this?
 232  */
 233 static u32 functionality(struct i2c_adapter *adap)
 234 {
 235         return I2C_FUNC_SMBUS_EMUL;
 236 }
 237
 238 static struct i2c_algorithm algo = {
 239         .master_xfer   = stk1160_i2c_xfer,
 240         .functionality = functionality,
 241 };
 242
 243 static struct i2c_adapter adap_template = {
 244         .owner = THIS_MODULE,
 245         .name = "stk1160",
 246         .algo = &algo,
 247 };
 248
 249 static struct i2c_client client_template = {
 250         .name = "stk1160 internal",
 251 };
 252
 253 /*
 254  * stk1160_i2c_register()
 255  * register i2c bus
 256  */
 257 int stk1160_i2c_register(struct stk1160 *dev)
 258 {
 259         int rc;
 260
 261         dev->i2c_adap = adap_template;
 262         dev->i2c_adap.dev.parent = dev->dev;
 263         strcpy(dev->i2c_adap.name, "stk1160");
 264         dev->i2c_adap.algo_data = dev;
 265
 266         i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
 267
 268         rc = i2c_add_adapter(&dev->i2c_adap);
 269         if (rc < 0) {
 270                 stk1160_err("cannot add i2c adapter (%d)\n", rc);
 271                 return rc;
 272         }
 273
 274         dev->i2c_client = client_template;
 275         dev->i2c_client.adapter = &dev->i2c_adap;
 276
 277         /* Set i2c clock divider device address */
 278         stk1160_write_reg(dev, STK1160_SICTL_CD,  0x0f);
 279
 280         /* ??? */
 281         stk1160_write_reg(dev, STK1160_ASIC + 3,  0x00);
 282
 283         return 0;
 284 }
 285
 286 /*
 287  * stk1160_i2c_unregister()
 288  * unregister i2c_bus
 289  */
 290 int stk1160_i2c_unregister(struct stk1160 *dev)
 291 {
 292         i2c_del_adapter(&dev->i2c_adap);
 293         return 0;
 294 }