drivers/media/pci/solo6x10/solo6x10-i2c.c

   1 /*
   2  * Copyright (C) 2010-2013 Bluecherry, LLC <http://www.bluecherrydvr.com>
   3  *
   4  * Original author:
   5  * Ben Collins <bcollins@ubuntu.com>
   6  *
   7  * Additional work by:
   8  * John Brooks <john.brooks@bluecherry.net>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  */
  20
  21 /* XXX: The SOLO6x10 i2c does not have separate interrupts for each i2c
  22  * channel. The bus can only handle one i2c event at a time. The below handles
  23  * this all wrong. We should be using the status registers to see if the bus
  24  * is in use, and have a global lock to check the status register. Also,
  25  * the bulk of the work should be handled out-of-interrupt. The ugly loops
  26  * that occur during interrupt scare me. The ISR should merely signal
  27  * thread context, ACK the interrupt, and move on. -- BenC */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/sched/signal.h>
  31
  32 #include "solo6x10.h"
  33
  34 u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
  35 {
  36         struct i2c_msg msgs[2];
  37         u8 data;
  38
  39         msgs[0].flags = 0;
  40         msgs[0].addr = addr;
  41         msgs[0].len = 1;
  42         msgs[0].buf = &off;
  43
  44         msgs[1].flags = I2C_M_RD;
  45         msgs[1].addr = addr;
  46         msgs[1].len = 1;
  47         msgs[1].buf = &data;
  48
  49         i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
  50
  51         return data;
  52 }
  53
  54 void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
  55                         u8 off, u8 data)
  56 {
  57         struct i2c_msg msgs;
  58         u8 buf[2];
  59
  60         buf[0] = off;
  61         buf[1] = data;
  62         msgs.flags = 0;
  63         msgs.addr = addr;
  64         msgs.len = 2;
  65         msgs.buf = buf;
  66
  67         i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
  68 }
  69
  70 static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
  71 {
  72         u32 ctrl;
  73
  74         ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
  75
  76         if (solo_dev->i2c_state == IIC_STATE_START)
  77                 ctrl |= SOLO_IIC_START;
  78
  79         if (wr) {
  80                 ctrl |= SOLO_IIC_WRITE;
  81         } else {
  82                 ctrl |= SOLO_IIC_READ;
  83                 if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
  84                         ctrl |= SOLO_IIC_ACK_EN;
  85         }
  86
  87         if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
  88                 ctrl |= SOLO_IIC_STOP;
  89
  90         solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
  91 }
  92
  93 static void solo_i2c_start(struct solo_dev *solo_dev)
  94 {
  95         u32 addr = solo_dev->i2c_msg->addr << 1;
  96
  97         if (solo_dev->i2c_msg->flags & I2C_M_RD)
  98                 addr |= 1;
  99
 100         solo_dev->i2c_state = IIC_STATE_START;
 101         solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
 102         solo_i2c_flush(solo_dev, 1);
 103 }
 104
 105 static void solo_i2c_stop(struct solo_dev *solo_dev)
 106 {
 107         solo_irq_off(solo_dev, SOLO_IRQ_IIC);
 108         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 109         solo_dev->i2c_state = IIC_STATE_STOP;
 110         wake_up(&solo_dev->i2c_wait);
 111 }
 112
 113 static int solo_i2c_handle_read(struct solo_dev *solo_dev)
 114 {
 115 prepare_read:
 116         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 117                 solo_i2c_flush(solo_dev, 0);
 118                 return 0;
 119         }
 120
 121         solo_dev->i2c_msg_ptr = 0;
 122         solo_dev->i2c_msg++;
 123         solo_dev->i2c_msg_num--;
 124
 125         if (solo_dev->i2c_msg_num == 0) {
 126                 solo_i2c_stop(solo_dev);
 127                 return 0;
 128         }
 129
 130         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 131                 solo_i2c_start(solo_dev);
 132         } else {
 133                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 134                         goto prepare_read;
 135                 else
 136                         solo_i2c_stop(solo_dev);
 137         }
 138
 139         return 0;
 140 }
 141
 142 static int solo_i2c_handle_write(struct solo_dev *solo_dev)
 143 {
 144 retry_write:
 145         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 146                 solo_reg_write(solo_dev, SOLO_IIC_TXD,
 147                                solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
 148                 solo_dev->i2c_msg_ptr++;
 149                 solo_i2c_flush(solo_dev, 1);
 150                 return 0;
 151         }
 152
 153         solo_dev->i2c_msg_ptr = 0;
 154         solo_dev->i2c_msg++;
 155         solo_dev->i2c_msg_num--;
 156
 157         if (solo_dev->i2c_msg_num == 0) {
 158                 solo_i2c_stop(solo_dev);
 159                 return 0;
 160         }
 161
 162         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 163                 solo_i2c_start(solo_dev);
 164         } else {
 165                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 166                         solo_i2c_stop(solo_dev);
 167                 else
 168                         goto retry_write;
 169         }
 170
 171         return 0;
 172 }
 173
 174 int solo_i2c_isr(struct solo_dev *solo_dev)
 175 {
 176         u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
 177         int ret = -EINVAL;
 178
 179
 180         if (CHK_FLAGS(status, SOLO_IIC_STATE_TRNS | SOLO_IIC_STATE_SIG_ERR)
 181             || solo_dev->i2c_id < 0) {
 182                 solo_i2c_stop(solo_dev);
 183                 return -ENXIO;
 184         }
 185
 186         switch (solo_dev->i2c_state) {
 187         case IIC_STATE_START:
 188                 if (solo_dev->i2c_msg->flags & I2C_M_RD) {
 189                         solo_dev->i2c_state = IIC_STATE_READ;
 190                         ret = solo_i2c_handle_read(solo_dev);
 191                         break;
 192                 }
 193
 194                 solo_dev->i2c_state = IIC_STATE_WRITE;
 195                 /* fall through */
 196         case IIC_STATE_WRITE:
 197                 ret = solo_i2c_handle_write(solo_dev);
 198                 break;
 199
 200         case IIC_STATE_READ:
 201                 solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
 202                         solo_reg_read(solo_dev, SOLO_IIC_RXD);
 203                 solo_dev->i2c_msg_ptr++;
 204
 205                 ret = solo_i2c_handle_read(solo_dev);
 206                 break;
 207
 208         default:
 209                 solo_i2c_stop(solo_dev);
 210         }
 211
 212         return ret;
 213 }
 214
 215 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
 216                                 struct i2c_msg msgs[], int num)
 217 {
 218         struct solo_dev *solo_dev = adap->algo_data;
 219         unsigned long timeout;
 220         int ret;
 221         int i;
 222         DEFINE_WAIT(wait);
 223
 224         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 225                 if (&solo_dev->i2c_adap[i] == adap)
 226                         break;
 227         }
 228
 229         if (i == SOLO_I2C_ADAPTERS)
 230                 return num; /* XXX Right return value for failure? */
 231
 232         mutex_lock(&solo_dev->i2c_mutex);
 233         solo_dev->i2c_id = i;
 234         solo_dev->i2c_msg = msgs;
 235         solo_dev->i2c_msg_num = num;
 236         solo_dev->i2c_msg_ptr = 0;
 237
 238         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 239         solo_irq_on(solo_dev, SOLO_IRQ_IIC);
 240         solo_i2c_start(solo_dev);
 241
 242         timeout = HZ / 2;
 243
 244         for (;;) {
 245                 prepare_to_wait(&solo_dev->i2c_wait, &wait,
 246                                 TASK_INTERRUPTIBLE);
 247
 248                 if (solo_dev->i2c_state == IIC_STATE_STOP)
 249                         break;
 250
 251                 timeout = schedule_timeout(timeout);
 252                 if (!timeout)
 253                         break;
 254
 255                 if (signal_pending(current))
 256                         break;
 257         }
 258
 259         finish_wait(&solo_dev->i2c_wait, &wait);
 260         ret = num - solo_dev->i2c_msg_num;
 261         solo_dev->i2c_state = IIC_STATE_IDLE;
 262         solo_dev->i2c_id = -1;
 263
 264         mutex_unlock(&solo_dev->i2c_mutex);
 265
 266         return ret;
 267 }
 268
 269 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
 270 {
 271         return I2C_FUNC_I2C;
 272 }
 273
 274 static const struct i2c_algorithm solo_i2c_algo = {
 275         .master_xfer    = solo_i2c_master_xfer,
 276         .functionality  = solo_i2c_functionality,
 277 };
 278
 279 int solo_i2c_init(struct solo_dev *solo_dev)
 280 {
 281         int i;
 282         int ret;
 283
 284         solo_reg_write(solo_dev, SOLO_IIC_CFG,
 285                        SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
 286
 287         solo_dev->i2c_id = -1;
 288         solo_dev->i2c_state = IIC_STATE_IDLE;
 289         init_waitqueue_head(&solo_dev->i2c_wait);
 290         mutex_init(&solo_dev->i2c_mutex);
 291
 292         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 293                 struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
 294
 295                 snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
 296                          SOLO6X10_NAME, i);
 297                 adap->algo = &solo_i2c_algo;
 298                 adap->algo_data = solo_dev;
 299                 adap->retries = 1;
 300                 adap->dev.parent = &solo_dev->pdev->dev;
 301
 302                 ret = i2c_add_adapter(adap);
 303                 if (ret) {
 304                         adap->algo_data = NULL;
 305                         break;
 306                 }
 307         }
 308
 309         if (ret) {
 310                 for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 311                         if (!solo_dev->i2c_adap[i].algo_data)
 312                                 break;
 313                         i2c_del_adapter(&solo_dev->i2c_adap[i]);
 314                         solo_dev->i2c_adap[i].algo_data = NULL;
 315                 }
 316                 return ret;
 317         }
 318
 319         return 0;
 320 }
 321
 322 void solo_i2c_exit(struct solo_dev *solo_dev)
 323 {
 324         int i;
 325
 326         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 327                 if (!solo_dev->i2c_adap[i].algo_data)
 328                         continue;
 329                 i2c_del_adapter(&solo_dev->i2c_adap[i]);
 330                 solo_dev->i2c_adap[i].algo_data = NULL;
 331         }
 332 }