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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * STK1160 driver
   4  *
   5  * Copyright (C) 2012 Ezequiel Garcia
   6  * <elezegarcia--a.t--gmail.com>
   7  *
   8  * Based on Easycap driver by R.M. Thomas
   9  *      Copyright (C) 2010 R.M. Thomas
  10  *      <rmthomas--a.t--sciolus.org>
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/usb.h>
  15 #include <linux/i2c.h>
  16
  17 #include "stk1160.h"
  18 #include "stk1160-reg.h"
  19
  20 static unsigned int i2c_debug;
  21 module_param(i2c_debug, int, 0644);
  22 MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");
  23
  24 #define dprintk_i2c(fmt, args...)                               \
  25 do {                                                            \
  26         if (i2c_debug)                                          \
  27                 printk(KERN_DEBUG fmt, ##args);                 \
  28 } while (0)
  29
  30 static int stk1160_i2c_busy_wait(struct stk1160 *dev, u8 wait_bit_mask)
  31 {
  32         unsigned long end;
  33         u8 flag;
  34
  35         /* Wait until read/write finish bit is set */
  36         end = jiffies + msecs_to_jiffies(STK1160_I2C_TIMEOUT);
  37         while (time_is_after_jiffies(end)) {
  38
  39                 stk1160_read_reg(dev, STK1160_SICTL+1, &flag);
  40                 /* read/write done? */
  41                 if (flag & wait_bit_mask)
  42                         goto done;
  43
  44                 usleep_range(10 * USEC_PER_MSEC, 20 * USEC_PER_MSEC);
  45         }
  46
  47         return -ETIMEDOUT;
  48
  49 done:
  50         return 0;
  51 }
  52
  53 static int stk1160_i2c_write_reg(struct stk1160 *dev, u8 addr,
  54                 u8 reg, u8 value)
  55 {
  56         int rc;
  57
  58         /* Set serial device address */
  59         rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
  60         if (rc < 0)
  61                 return rc;
  62
  63         /* Set i2c device register sub-address */
  64         rc = stk1160_write_reg(dev, STK1160_SBUSW_WA, reg);
  65         if (rc < 0)
  66                 return rc;
  67
  68         /* Set i2c device register value */
  69         rc = stk1160_write_reg(dev, STK1160_SBUSW_WD, value);
  70         if (rc < 0)
  71                 return rc;
  72
  73         /* Start write now */
  74         rc = stk1160_write_reg(dev, STK1160_SICTL, 0x01);
  75         if (rc < 0)
  76                 return rc;
  77
  78         rc = stk1160_i2c_busy_wait(dev, 0x04);
  79         if (rc < 0)
  80                 return rc;
  81
  82         return 0;
  83 }
  84
  85 static int stk1160_i2c_read_reg(struct stk1160 *dev, u8 addr,
  86                 u8 reg, u8 *value)
  87 {
  88         int rc;
  89
  90         /* Set serial device address */
  91         rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
  92         if (rc < 0)
  93                 return rc;
  94
  95         /* Set i2c device register sub-address */
  96         rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, reg);
  97         if (rc < 0)
  98                 return rc;
  99
 100         /* Start read now */
 101         rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
 102         if (rc < 0)
 103                 return rc;
 104
 105         rc = stk1160_i2c_busy_wait(dev, 0x01);
 106         if (rc < 0)
 107                 return rc;
 108
 109         rc = stk1160_read_reg(dev, STK1160_SBUSR_RD, value);
 110         if (rc < 0)
 111                 return rc;
 112
 113         return 0;
 114 }
 115
 116 /*
 117  * stk1160_i2c_check_for_device()
 118  * check if there is a i2c_device at the supplied address
 119  */
 120 static int stk1160_i2c_check_for_device(struct stk1160 *dev,
 121                 unsigned char addr)
 122 {
 123         int rc;
 124
 125         /* Set serial device address */
 126         rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
 127         if (rc < 0)
 128                 return rc;
 129
 130         /* Set device sub-address, we'll chip version reg */
 131         rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, 0x00);
 132         if (rc < 0)
 133                 return rc;
 134
 135         /* Start read now */
 136         rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
 137         if (rc < 0)
 138                 return rc;
 139
 140         rc = stk1160_i2c_busy_wait(dev, 0x01);
 141         if (rc < 0)
 142                 return -ENODEV;
 143
 144         return 0;
 145 }
 146
 147 /*
 148  * stk1160_i2c_xfer()
 149  * the main i2c transfer function
 150  */
 151 static int stk1160_i2c_xfer(struct i2c_adapter *i2c_adap,
 152                            struct i2c_msg msgs[], int num)
 153 {
 154         struct stk1160 *dev = i2c_adap->algo_data;
 155         int addr, rc, i;
 156
 157         for (i = 0; i < num; i++) {
 158                 addr = msgs[i].addr << 1;
 159                 dprintk_i2c("%s: addr=%x", __func__, addr);
 160
 161                 if (!msgs[i].len) {
 162                         /* no len: check only for device presence */
 163                         rc = stk1160_i2c_check_for_device(dev, addr);
 164                         if (rc < 0) {
 165                                 dprintk_i2c(" no device\n");
 166                                 return rc;
 167                         }
 168
 169                 } else if (msgs[i].flags & I2C_M_RD) {
 170                         /* read request without preceding register selection */
 171                         dprintk_i2c(" subaddr not selected");
 172                         rc = -EOPNOTSUPP;
 173                         goto err;
 174
 175                 } else if (i + 1 < num && msgs[i].len <= 2 &&
 176                            (msgs[i + 1].flags & I2C_M_RD) &&
 177                            msgs[i].addr == msgs[i + 1].addr) {
 178
 179                         if (msgs[i].len != 1 || msgs[i + 1].len != 1) {
 180                                 dprintk_i2c(" len not supported");
 181                                 rc = -EOPNOTSUPP;
 182                                 goto err;
 183                         }
 184
 185                         dprintk_i2c(" subaddr=%x", msgs[i].buf[0]);
 186
 187                         rc = stk1160_i2c_read_reg(dev, addr, msgs[i].buf[0],
 188                                 msgs[i + 1].buf);
 189
 190                         dprintk_i2c(" read=%x", *msgs[i + 1].buf);
 191
 192                         /* consumed two msgs, so we skip one of them */
 193                         i++;
 194
 195                 } else {
 196                         if (msgs[i].len != 2) {
 197                                 dprintk_i2c(" len not supported");
 198                                 rc = -EOPNOTSUPP;
 199                                 goto err;
 200                         }
 201
 202                         dprintk_i2c(" subaddr=%x write=%x",
 203                                 msgs[i].buf[0],  msgs[i].buf[1]);
 204
 205                         rc = stk1160_i2c_write_reg(dev, addr, msgs[i].buf[0],
 206                                 msgs[i].buf[1]);
 207                 }
 208
 209                 if (rc < 0)
 210                         goto err;
 211                 dprintk_i2c(" OK\n");
 212         }
 213
 214         return num;
 215 err:
 216         dprintk_i2c(" ERROR: %d\n", rc);
 217         return num;
 218 }
 219
 220 /*
 221  * functionality(), what da heck is this?
 222  */
 223 static u32 functionality(struct i2c_adapter *adap)
 224 {
 225         return I2C_FUNC_SMBUS_EMUL;
 226 }
 227
 228 static const struct i2c_algorithm algo = {
 229         .master_xfer   = stk1160_i2c_xfer,
 230         .functionality = functionality,
 231 };
 232
 233 static const struct i2c_adapter adap_template = {
 234         .owner = THIS_MODULE,
 235         .name = "stk1160",
 236         .algo = &algo,
 237 };
 238
 239 static const struct i2c_client client_template = {
 240         .name = "stk1160 internal",
 241 };
 242
 243 /*
 244  * stk1160_i2c_register()
 245  * register i2c bus
 246  */
 247 int stk1160_i2c_register(struct stk1160 *dev)
 248 {
 249         int rc;
 250
 251         dev->i2c_adap = adap_template;
 252         dev->i2c_adap.dev.parent = dev->dev;
 253         strscpy(dev->i2c_adap.name, "stk1160", sizeof(dev->i2c_adap.name));
 254         dev->i2c_adap.algo_data = dev;
 255
 256         i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
 257
 258         rc = i2c_add_adapter(&dev->i2c_adap);
 259         if (rc < 0) {
 260                 stk1160_err("cannot add i2c adapter (%d)\n", rc);
 261                 return rc;
 262         }
 263
 264         dev->i2c_client = client_template;
 265         dev->i2c_client.adapter = &dev->i2c_adap;
 266
 267         /* Set i2c clock divider device address */
 268         stk1160_write_reg(dev, STK1160_SICTL_CD,  0x0f);
 269
 270         /* ??? */
 271         stk1160_write_reg(dev, STK1160_ASIC + 3,  0x00);
 272
 273         return 0;
 274 }
 275
 276 /*
 277  * stk1160_i2c_unregister()
 278  * unregister i2c_bus
 279  */
 280 int stk1160_i2c_unregister(struct stk1160 *dev)
 281 {
 282         i2c_del_adapter(&dev->i2c_adap);
 283         return 0;
 284 }