drivers/staging/solo6x10/solo6010-i2c.c

   1 /*
   2  * Copyright (C) 2010 Bluecherry, LLC www.bluecherrydvr.com
   3  * Copyright (C) 2010 Ben Collins <bcollins@bluecherry.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  */
  19
  20 /* XXX: The SOLO6010 i2c does not have separate interrupts for each i2c
  21  * channel. The bus can only handle one i2c event at a time. The below handles
  22  * this all wrong. We should be using the status registers to see if the bus
  23  * is in use, and have a global lock to check the status register. Also,
  24  * the bulk of the work should be handled out-of-interrupt. The ugly loops
  25  * that occur during interrupt scare me. The ISR should merely signal
  26  * thread context, ACK the interrupt, and move on. -- BenC */
  27
  28 #include <linux/kernel.h>
  29
  30 #include "solo6010.h"
  31
  32 u8 solo_i2c_readbyte(struct solo6010_dev *solo_dev, int id, u8 addr, u8 off)
  33 {
  34         struct i2c_msg msgs[2];
  35         u8 data;
  36
  37         msgs[0].flags = 0;
  38         msgs[0].addr = addr;
  39         msgs[0].len = 1;
  40         msgs[0].buf = &off;
  41
  42         msgs[1].flags = I2C_M_RD;
  43         msgs[1].addr = addr;
  44         msgs[1].len = 1;
  45         msgs[1].buf = &data;
  46
  47         i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
  48
  49         return data;
  50 }
  51
  52 void solo_i2c_writebyte(struct solo6010_dev *solo_dev, int id, u8 addr,
  53                         u8 off, u8 data)
  54 {
  55         struct i2c_msg msgs;
  56         u8 buf[2];
  57
  58         buf[0] = off;
  59         buf[1] = data;
  60         msgs.flags = 0;
  61         msgs.addr = addr;
  62         msgs.len = 2;
  63         msgs.buf = buf;
  64
  65         i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
  66 }
  67
  68 static void solo_i2c_flush(struct solo6010_dev *solo_dev, int wr)
  69 {
  70         u32 ctrl;
  71
  72         ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
  73
  74         if (solo_dev->i2c_state == IIC_STATE_START)
  75                 ctrl |= SOLO_IIC_START;
  76
  77         if (wr) {
  78                 ctrl |= SOLO_IIC_WRITE;
  79         } else {
  80                 ctrl |= SOLO_IIC_READ;
  81                 if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
  82                         ctrl |= SOLO_IIC_ACK_EN;
  83         }
  84
  85         if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
  86                 ctrl |= SOLO_IIC_STOP;
  87
  88         solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
  89 }
  90
  91 static void solo_i2c_start(struct solo6010_dev *solo_dev)
  92 {
  93         u32 addr = solo_dev->i2c_msg->addr << 1;
  94
  95         if (solo_dev->i2c_msg->flags & I2C_M_RD)
  96                 addr |= 1;
  97
  98         solo_dev->i2c_state = IIC_STATE_START;
  99         solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
 100         solo_i2c_flush(solo_dev, 1);
 101 }
 102
 103 static void solo_i2c_stop(struct solo6010_dev *solo_dev)
 104 {
 105         solo6010_irq_off(solo_dev, SOLO_IRQ_IIC);
 106         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 107         solo_dev->i2c_state = IIC_STATE_STOP;
 108         wake_up(&solo_dev->i2c_wait);
 109 }
 110
 111 static int solo_i2c_handle_read(struct solo6010_dev *solo_dev)
 112 {
 113 prepare_read:
 114         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 115                 solo_i2c_flush(solo_dev, 0);
 116                 return 0;
 117         }
 118
 119         solo_dev->i2c_msg_ptr = 0;
 120         solo_dev->i2c_msg++;
 121         solo_dev->i2c_msg_num--;
 122
 123         if (solo_dev->i2c_msg_num == 0) {
 124                 solo_i2c_stop(solo_dev);
 125                 return 0;
 126         }
 127
 128         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 129                 solo_i2c_start(solo_dev);
 130         } else {
 131                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 132                         goto prepare_read;
 133                 else
 134                         solo_i2c_stop(solo_dev);
 135         }
 136
 137         return 0;
 138 }
 139
 140 static int solo_i2c_handle_write(struct solo6010_dev *solo_dev)
 141 {
 142 retry_write:
 143         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 144                 solo_reg_write(solo_dev, SOLO_IIC_TXD,
 145                                solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
 146                 solo_dev->i2c_msg_ptr++;
 147                 solo_i2c_flush(solo_dev, 1);
 148                 return 0;
 149         }
 150
 151         solo_dev->i2c_msg_ptr = 0;
 152         solo_dev->i2c_msg++;
 153         solo_dev->i2c_msg_num--;
 154
 155         if (solo_dev->i2c_msg_num == 0) {
 156                 solo_i2c_stop(solo_dev);
 157                 return 0;
 158         }
 159
 160         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 161                 solo_i2c_start(solo_dev);
 162         } else {
 163                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 164                         solo_i2c_stop(solo_dev);
 165                 else
 166                         goto retry_write;
 167         }
 168
 169         return 0;
 170 }
 171
 172 int solo_i2c_isr(struct solo6010_dev *solo_dev)
 173 {
 174         u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
 175         int ret = -EINVAL;
 176
 177         solo_reg_write(solo_dev, SOLO_IRQ_STAT, SOLO_IRQ_IIC);
 178
 179         if (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 solo6010_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         solo6010_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, TASK_INTERRUPTIBLE);
 244
 245                 if (solo_dev->i2c_state == IIC_STATE_STOP)
 246                         break;
 247
 248                 timeout = schedule_timeout(timeout);
 249                 if (!timeout)
 250                         break;
 251
 252                 if (signal_pending(current))
 253                         break;
 254         }
 255
 256         finish_wait(&solo_dev->i2c_wait, &wait);
 257         ret = num - solo_dev->i2c_msg_num;
 258         solo_dev->i2c_state = IIC_STATE_IDLE;
 259         solo_dev->i2c_id = -1;
 260
 261         mutex_unlock(&solo_dev->i2c_mutex);
 262
 263         return ret;
 264 }
 265
 266 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
 267 {
 268         return I2C_FUNC_I2C;
 269 }
 270
 271 static struct i2c_algorithm solo_i2c_algo = {
 272         .master_xfer    = solo_i2c_master_xfer,
 273         .functionality  = solo_i2c_functionality,
 274 };
 275
 276 int solo_i2c_init(struct solo6010_dev *solo_dev)
 277 {
 278         int i;
 279         int ret;
 280
 281         solo_reg_write(solo_dev, SOLO_IIC_CFG,
 282                        SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
 283
 284         solo_dev->i2c_id = -1;
 285         solo_dev->i2c_state = IIC_STATE_IDLE;
 286         init_waitqueue_head(&solo_dev->i2c_wait);
 287         mutex_init(&solo_dev->i2c_mutex);
 288
 289         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 290                 struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
 291
 292                 snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
 293                          SOLO6010_NAME, i);
 294                 adap->algo = &solo_i2c_algo;
 295                 adap->algo_data = solo_dev;
 296                 adap->retries = 1;
 297                 adap->dev.parent = &solo_dev->pdev->dev;
 298
 299                 ret = i2c_add_adapter(adap);
 300                 if (ret) {
 301                         adap->algo_data = NULL;
 302                         break;
 303                 }
 304         }
 305
 306         if (ret) {
 307                 for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 308                         if (!solo_dev->i2c_adap[i].algo_data)
 309                                 break;
 310                         i2c_del_adapter(&solo_dev->i2c_adap[i]);
 311                         solo_dev->i2c_adap[i].algo_data = NULL;
 312                 }
 313                 return ret;
 314         }
 315
 316         dev_info(&solo_dev->pdev->dev, "Enabled %d i2c adapters\n",
 317                  SOLO_I2C_ADAPTERS);
 318
 319         return 0;
 320 }
 321
 322 void solo_i2c_exit(struct solo6010_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 }