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         case IIC_STATE_WRITE:
 196                 ret = solo_i2c_handle_write(solo_dev);
 197                 break;
 198
 199         case IIC_STATE_READ:
 200                 solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
 201                         solo_reg_read(solo_dev, SOLO_IIC_RXD);
 202                 solo_dev->i2c_msg_ptr++;
 203
 204                 ret = solo_i2c_handle_read(solo_dev);
 205                 break;
 206
 207         default:
 208                 solo_i2c_stop(solo_dev);
 209         }
 210
 211         return ret;
 212 }
 213
 214 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
 215                                 struct i2c_msg msgs[], int num)
 216 {
 217         struct solo_dev *solo_dev = adap->algo_data;
 218         unsigned long timeout;
 219         int ret;
 220         int i;
 221         DEFINE_WAIT(wait);
 222
 223         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 224                 if (&solo_dev->i2c_adap[i] == adap)
 225                         break;
 226         }
 227
 228         if (i == SOLO_I2C_ADAPTERS)
 229                 return num; /* XXX Right return value for failure? */
 230
 231         mutex_lock(&solo_dev->i2c_mutex);
 232         solo_dev->i2c_id = i;
 233         solo_dev->i2c_msg = msgs;
 234         solo_dev->i2c_msg_num = num;
 235         solo_dev->i2c_msg_ptr = 0;
 236
 237         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 238         solo_irq_on(solo_dev, SOLO_IRQ_IIC);
 239         solo_i2c_start(solo_dev);
 240
 241         timeout = HZ / 2;
 242
 243         for (;;) {
 244                 prepare_to_wait(&solo_dev->i2c_wait, &wait,
 245                                 TASK_INTERRUPTIBLE);
 246
 247                 if (solo_dev->i2c_state == IIC_STATE_STOP)
 248                         break;
 249
 250                 timeout = schedule_timeout(timeout);
 251                 if (!timeout)
 252                         break;
 253
 254                 if (signal_pending(current))
 255                         break;
 256         }
 257
 258         finish_wait(&solo_dev->i2c_wait, &wait);
 259         ret = num - solo_dev->i2c_msg_num;
 260         solo_dev->i2c_state = IIC_STATE_IDLE;
 261         solo_dev->i2c_id = -1;
 262
 263         mutex_unlock(&solo_dev->i2c_mutex);
 264
 265         return ret;
 266 }
 267
 268 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
 269 {
 270         return I2C_FUNC_I2C;
 271 }
 272
 273 static const struct i2c_algorithm solo_i2c_algo = {
 274         .master_xfer    = solo_i2c_master_xfer,
 275         .functionality  = solo_i2c_functionality,
 276 };
 277
 278 int solo_i2c_init(struct solo_dev *solo_dev)
 279 {
 280         int i;
 281         int ret;
 282
 283         solo_reg_write(solo_dev, SOLO_IIC_CFG,
 284                        SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
 285
 286         solo_dev->i2c_id = -1;
 287         solo_dev->i2c_state = IIC_STATE_IDLE;
 288         init_waitqueue_head(&solo_dev->i2c_wait);
 289         mutex_init(&solo_dev->i2c_mutex);
 290
 291         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 292                 struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
 293
 294                 snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
 295                          SOLO6X10_NAME, i);
 296                 adap->algo = &solo_i2c_algo;
 297                 adap->algo_data = solo_dev;
 298                 adap->retries = 1;
 299                 adap->dev.parent = &solo_dev->pdev->dev;
 300
 301                 ret = i2c_add_adapter(adap);
 302                 if (ret) {
 303                         adap->algo_data = NULL;
 304                         break;
 305                 }
 306         }
 307
 308         if (ret) {
 309                 for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 310                         if (!solo_dev->i2c_adap[i].algo_data)
 311                                 break;
 312                         i2c_del_adapter(&solo_dev->i2c_adap[i]);
 313                         solo_dev->i2c_adap[i].algo_data = NULL;
 314                 }
 315                 return ret;
 316         }
 317
 318         return 0;
 319 }
 320
 321 void solo_i2c_exit(struct solo_dev *solo_dev)
 322 {
 323         int i;
 324
 325         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 326                 if (!solo_dev->i2c_adap[i].algo_data)
 327                         continue;
 328                 i2c_del_adapter(&solo_dev->i2c_adap[i]);
 329                 solo_dev->i2c_adap[i].algo_data = NULL;
 330         }
 331 }