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
  31 #include "solo6x10.h"
  32
  33 u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
  34 {
  35         struct i2c_msg msgs[2];
  36         u8 data;
  37
  38         msgs[0].flags = 0;
  39         msgs[0].addr = addr;
  40         msgs[0].len = 1;
  41         msgs[0].buf = &off;
  42
  43         msgs[1].flags = I2C_M_RD;
  44         msgs[1].addr = addr;
  45         msgs[1].len = 1;
  46         msgs[1].buf = &data;
  47
  48         i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
  49
  50         return data;
  51 }
  52
  53 void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
  54                         u8 off, u8 data)
  55 {
  56         struct i2c_msg msgs;
  57         u8 buf[2];
  58
  59         buf[0] = off;
  60         buf[1] = data;
  61         msgs.flags = 0;
  62         msgs.addr = addr;
  63         msgs.len = 2;
  64         msgs.buf = buf;
  65
  66         i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
  67 }
  68
  69 static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
  70 {
  71         u32 ctrl;
  72
  73         ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
  74
  75         if (solo_dev->i2c_state == IIC_STATE_START)
  76                 ctrl |= SOLO_IIC_START;
  77
  78         if (wr) {
  79                 ctrl |= SOLO_IIC_WRITE;
  80         } else {
  81                 ctrl |= SOLO_IIC_READ;
  82                 if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
  83                         ctrl |= SOLO_IIC_ACK_EN;
  84         }
  85
  86         if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
  87                 ctrl |= SOLO_IIC_STOP;
  88
  89         solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
  90 }
  91
  92 static void solo_i2c_start(struct solo_dev *solo_dev)
  93 {
  94         u32 addr = solo_dev->i2c_msg->addr << 1;
  95
  96         if (solo_dev->i2c_msg->flags & I2C_M_RD)
  97                 addr |= 1;
  98
  99         solo_dev->i2c_state = IIC_STATE_START;
 100         solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
 101         solo_i2c_flush(solo_dev, 1);
 102 }
 103
 104 static void solo_i2c_stop(struct solo_dev *solo_dev)
 105 {
 106         solo_irq_off(solo_dev, SOLO_IRQ_IIC);
 107         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 108         solo_dev->i2c_state = IIC_STATE_STOP;
 109         wake_up(&solo_dev->i2c_wait);
 110 }
 111
 112 static int solo_i2c_handle_read(struct solo_dev *solo_dev)
 113 {
 114 prepare_read:
 115         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 116                 solo_i2c_flush(solo_dev, 0);
 117                 return 0;
 118         }
 119
 120         solo_dev->i2c_msg_ptr = 0;
 121         solo_dev->i2c_msg++;
 122         solo_dev->i2c_msg_num--;
 123
 124         if (solo_dev->i2c_msg_num == 0) {
 125                 solo_i2c_stop(solo_dev);
 126                 return 0;
 127         }
 128
 129         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 130                 solo_i2c_start(solo_dev);
 131         } else {
 132                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 133                         goto prepare_read;
 134                 else
 135                         solo_i2c_stop(solo_dev);
 136         }
 137
 138         return 0;
 139 }
 140
 141 static int solo_i2c_handle_write(struct solo_dev *solo_dev)
 142 {
 143 retry_write:
 144         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 145                 solo_reg_write(solo_dev, SOLO_IIC_TXD,
 146                                solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
 147                 solo_dev->i2c_msg_ptr++;
 148                 solo_i2c_flush(solo_dev, 1);
 149                 return 0;
 150         }
 151
 152         solo_dev->i2c_msg_ptr = 0;
 153         solo_dev->i2c_msg++;
 154         solo_dev->i2c_msg_num--;
 155
 156         if (solo_dev->i2c_msg_num == 0) {
 157                 solo_i2c_stop(solo_dev);
 158                 return 0;
 159         }
 160
 161         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 162                 solo_i2c_start(solo_dev);
 163         } else {
 164                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 165                         solo_i2c_stop(solo_dev);
 166                 else
 167                         goto retry_write;
 168         }
 169
 170         return 0;
 171 }
 172
 173 int solo_i2c_isr(struct solo_dev *solo_dev)
 174 {
 175         u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
 176         int ret = -EINVAL;
 177
 178
 179         if (CHK_FLAGS(status, SOLO_IIC_STATE_TRNS | SOLO_IIC_STATE_SIG_ERR)
 180             || solo_dev->i2c_id < 0) {
 181                 solo_i2c_stop(solo_dev);
 182                 return -ENXIO;
 183         }
 184
 185         switch (solo_dev->i2c_state) {
 186         case IIC_STATE_START:
 187                 if (solo_dev->i2c_msg->flags & I2C_M_RD) {
 188                         solo_dev->i2c_state = IIC_STATE_READ;
 189                         ret = solo_i2c_handle_read(solo_dev);
 190                         break;
 191                 }
 192
 193                 solo_dev->i2c_state = IIC_STATE_WRITE;
 194         case IIC_STATE_WRITE:
 195                 ret = solo_i2c_handle_write(solo_dev);
 196                 break;
 197
 198         case IIC_STATE_READ:
 199                 solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
 200                         solo_reg_read(solo_dev, SOLO_IIC_RXD);
 201                 solo_dev->i2c_msg_ptr++;
 202
 203                 ret = solo_i2c_handle_read(solo_dev);
 204                 break;
 205
 206         default:
 207                 solo_i2c_stop(solo_dev);
 208         }
 209
 210         return ret;
 211 }
 212
 213 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
 214                                 struct i2c_msg msgs[], int num)
 215 {
 216         struct solo_dev *solo_dev = adap->algo_data;
 217         unsigned long timeout;
 218         int ret;
 219         int i;
 220         DEFINE_WAIT(wait);
 221
 222         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 223                 if (&solo_dev->i2c_adap[i] == adap)
 224                         break;
 225         }
 226
 227         if (i == SOLO_I2C_ADAPTERS)
 228                 return num; /* XXX Right return value for failure? */
 229
 230         mutex_lock(&solo_dev->i2c_mutex);
 231         solo_dev->i2c_id = i;
 232         solo_dev->i2c_msg = msgs;
 233         solo_dev->i2c_msg_num = num;
 234         solo_dev->i2c_msg_ptr = 0;
 235
 236         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 237         solo_irq_on(solo_dev, SOLO_IRQ_IIC);
 238         solo_i2c_start(solo_dev);
 239
 240         timeout = HZ / 2;
 241
 242         for (;;) {
 243                 prepare_to_wait(&solo_dev->i2c_wait, &wait,
 244                                 TASK_INTERRUPTIBLE);
 245
 246                 if (solo_dev->i2c_state == IIC_STATE_STOP)
 247                         break;
 248
 249                 timeout = schedule_timeout(timeout);
 250                 if (!timeout)
 251                         break;
 252
 253                 if (signal_pending(current))
 254                         break;
 255         }
 256
 257         finish_wait(&solo_dev->i2c_wait, &wait);
 258         ret = num - solo_dev->i2c_msg_num;
 259         solo_dev->i2c_state = IIC_STATE_IDLE;
 260         solo_dev->i2c_id = -1;
 261
 262         mutex_unlock(&solo_dev->i2c_mutex);
 263
 264         return ret;
 265 }
 266
 267 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
 268 {
 269         return I2C_FUNC_I2C;
 270 }
 271
 272 static const struct i2c_algorithm solo_i2c_algo = {
 273         .master_xfer    = solo_i2c_master_xfer,
 274         .functionality  = solo_i2c_functionality,
 275 };
 276
 277 int solo_i2c_init(struct solo_dev *solo_dev)
 278 {
 279         int i;
 280         int ret;
 281
 282         solo_reg_write(solo_dev, SOLO_IIC_CFG,
 283                        SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
 284
 285         solo_dev->i2c_id = -1;
 286         solo_dev->i2c_state = IIC_STATE_IDLE;
 287         init_waitqueue_head(&solo_dev->i2c_wait);
 288         mutex_init(&solo_dev->i2c_mutex);
 289
 290         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 291                 struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
 292
 293                 snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
 294                          SOLO6X10_NAME, i);
 295                 adap->algo = &solo_i2c_algo;
 296                 adap->algo_data = solo_dev;
 297                 adap->retries = 1;
 298                 adap->dev.parent = &solo_dev->pdev->dev;
 299
 300                 ret = i2c_add_adapter(adap);
 301                 if (ret) {
 302                         adap->algo_data = NULL;
 303                         break;
 304                 }
 305         }
 306
 307         if (ret) {
 308                 for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 309                         if (!solo_dev->i2c_adap[i].algo_data)
 310                                 break;
 311                         i2c_del_adapter(&solo_dev->i2c_adap[i]);
 312                         solo_dev->i2c_adap[i].algo_data = NULL;
 313                 }
 314                 return ret;
 315         }
 316
 317         return 0;
 318 }
 319
 320 void solo_i2c_exit(struct solo_dev *solo_dev)
 321 {
 322         int i;
 323
 324         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 325                 if (!solo_dev->i2c_adap[i].algo_data)
 326                         continue;
 327                 i2c_del_adapter(&solo_dev->i2c_adap[i]);
 328                 solo_dev->i2c_adap[i].algo_data = NULL;
 329         }
 330 }