drivers/i2c/busses/i2c-kempld.c

   1 /*
   2  * I2C bus driver for Kontron COM modules
   3  *
   4  * Copyright (c) 2010-2013 Kontron Europe GmbH
   5  * Author: Michael Brunner <michael.brunner@kontron.com>
   6  *
   7  * The driver is based on the i2c-ocores driver by Peter Korsgaard.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License 2 as published
  11  * by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/i2c.h>
  22 #include <linux/delay.h>
  23 #include <linux/mfd/kempld.h>
  24
  25 #define KEMPLD_I2C_PRELOW       0x0b
  26 #define KEMPLD_I2C_PREHIGH      0x0c
  27 #define KEMPLD_I2C_DATA         0x0e
  28
  29 #define KEMPLD_I2C_CTRL         0x0d
  30 #define I2C_CTRL_IEN            0x40
  31 #define I2C_CTRL_EN             0x80
  32
  33 #define KEMPLD_I2C_STAT         0x0f
  34 #define I2C_STAT_IF             0x01
  35 #define I2C_STAT_TIP            0x02
  36 #define I2C_STAT_ARBLOST        0x20
  37 #define I2C_STAT_BUSY           0x40
  38 #define I2C_STAT_NACK           0x80
  39
  40 #define KEMPLD_I2C_CMD          0x0f
  41 #define I2C_CMD_START           0x91
  42 #define I2C_CMD_STOP            0x41
  43 #define I2C_CMD_READ            0x21
  44 #define I2C_CMD_WRITE           0x11
  45 #define I2C_CMD_READ_ACK        0x21
  46 #define I2C_CMD_READ_NACK       0x29
  47 #define I2C_CMD_IACK            0x01
  48
  49 #define KEMPLD_I2C_FREQ_MAX     2700    /* 2.7 mHz */
  50 #define KEMPLD_I2C_FREQ_STD     100     /* 100 kHz */
  51
  52 enum {
  53         STATE_DONE = 0,
  54         STATE_INIT,
  55         STATE_ADDR,
  56         STATE_ADDR10,
  57         STATE_START,
  58         STATE_WRITE,
  59         STATE_READ,
  60         STATE_ERROR,
  61 };
  62
  63 struct kempld_i2c_data {
  64         struct device                   *dev;
  65         struct kempld_device_data       *pld;
  66         struct i2c_adapter              adap;
  67         struct i2c_msg                  *msg;
  68         int                             pos;
  69         int                             nmsgs;
  70         int                             state;
  71         bool                            was_active;
  72 };
  73
  74 static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
  75 module_param(bus_frequency, uint, 0);
  76 MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
  77                                 __MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");
  78
  79 static int i2c_bus = -1;
  80 module_param(i2c_bus, int, 0);
  81 MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");
  82
  83 static bool i2c_gpio_mux;
  84 module_param(i2c_gpio_mux, bool, 0);
  85 MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");
  86
  87 /*
  88  * kempld_get_mutex must be called prior to calling this function.
  89  */
  90 static int kempld_i2c_process(struct kempld_i2c_data *i2c)
  91 {
  92         struct kempld_device_data *pld = i2c->pld;
  93         u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
  94         struct i2c_msg *msg = i2c->msg;
  95         u8 addr;
  96
  97         /* Ready? */
  98         if (stat & I2C_STAT_TIP)
  99                 return -EBUSY;
 100
 101         if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
 102                 /* Stop has been sent */
 103                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
 104                 if (i2c->state == STATE_ERROR)
 105                         return -EIO;
 106                 return 0;
 107         }
 108
 109         /* Error? */
 110         if (stat & I2C_STAT_ARBLOST) {
 111                 i2c->state = STATE_ERROR;
 112                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 113                 return -EAGAIN;
 114         }
 115
 116         if (i2c->state == STATE_INIT) {
 117                 if (stat & I2C_STAT_BUSY)
 118                         return -EBUSY;
 119
 120                 i2c->state = STATE_ADDR;
 121         }
 122
 123         if (i2c->state == STATE_ADDR) {
 124                 /* 10 bit address? */
 125                 if (i2c->msg->flags & I2C_M_TEN) {
 126                         addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
 127                         i2c->state = STATE_ADDR10;
 128                 } else {
 129                         addr = (i2c->msg->addr << 1);
 130                         i2c->state = STATE_START;
 131                 }
 132
 133                 /* Set read bit if necessary */
 134                 addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
 135
 136                 kempld_write8(pld, KEMPLD_I2C_DATA, addr);
 137                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
 138
 139                 return 0;
 140         }
 141
 142         /* Second part of 10 bit addressing */
 143         if (i2c->state == STATE_ADDR10) {
 144                 kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
 145                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
 146
 147                 i2c->state = STATE_START;
 148                 return 0;
 149         }
 150
 151         if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
 152                 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 153
 154                 if (stat & I2C_STAT_NACK) {
 155                         i2c->state = STATE_ERROR;
 156                         kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 157                         return -ENXIO;
 158                 }
 159         } else {
 160                 msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
 161         }
 162
 163         if (i2c->pos >= msg->len) {
 164                 i2c->nmsgs--;
 165                 i2c->msg++;
 166                 i2c->pos = 0;
 167                 msg = i2c->msg;
 168
 169                 if (i2c->nmsgs) {
 170                         if (!(msg->flags & I2C_M_NOSTART)) {
 171                                 i2c->state = STATE_ADDR;
 172                                 return 0;
 173                         } else {
 174                                 i2c->state = (msg->flags & I2C_M_RD)
 175                                         ? STATE_READ : STATE_WRITE;
 176                         }
 177                 } else {
 178                         i2c->state = STATE_DONE;
 179                         kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 180                         return 0;
 181                 }
 182         }
 183
 184         if (i2c->state == STATE_READ) {
 185                 kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
 186                               I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
 187         } else {
 188                 kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
 189                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
 190         }
 191
 192         return 0;
 193 }
 194
 195 static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 196                                 int num)
 197 {
 198         struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
 199         struct kempld_device_data *pld = i2c->pld;
 200         unsigned long timeout = jiffies + HZ;
 201         int ret;
 202
 203         i2c->msg = msgs;
 204         i2c->pos = 0;
 205         i2c->nmsgs = num;
 206         i2c->state = STATE_INIT;
 207
 208         /* Handle the transfer */
 209         while (time_before(jiffies, timeout)) {
 210                 kempld_get_mutex(pld);
 211                 ret = kempld_i2c_process(i2c);
 212                 kempld_release_mutex(pld);
 213
 214                 if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
 215                         return (i2c->state == STATE_DONE) ? num : ret;
 216
 217                 if (ret == 0)
 218                         timeout = jiffies + HZ;
 219
 220                 usleep_range(5, 15);
 221         }
 222
 223         i2c->state = STATE_ERROR;
 224
 225         return -ETIMEDOUT;
 226 }
 227
 228 /*
 229  * kempld_get_mutex must be called prior to calling this function.
 230  */
 231 static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
 232 {
 233         struct kempld_device_data *pld = i2c->pld;
 234         u16 prescale_corr;
 235         long prescale;
 236         u8 ctrl;
 237         u8 stat;
 238         u8 cfg;
 239
 240         /* Make sure the device is disabled */
 241         ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 242         ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
 243         kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 244
 245         if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
 246                 bus_frequency = KEMPLD_I2C_FREQ_MAX;
 247
 248         if (pld->info.spec_major == 1)
 249                 prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
 250         else
 251                 prescale = pld->pld_clock / (bus_frequency * 4) - 3000;
 252
 253         if (prescale < 0)
 254                 prescale = 0;
 255
 256         /* Round to the best matching value */
 257         prescale_corr = prescale / 1000;
 258         if (prescale % 1000 >= 500)
 259                 prescale_corr++;
 260
 261         kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
 262         kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
 263
 264         /* Activate I2C bus output on GPIO pins */
 265         cfg = kempld_read8(pld, KEMPLD_CFG);
 266         if (i2c_gpio_mux)
 267                 cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
 268         else
 269                 cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
 270         kempld_write8(pld, KEMPLD_CFG, cfg);
 271
 272         /* Enable the device */
 273         kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
 274         ctrl |= I2C_CTRL_EN;
 275         kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 276
 277         stat = kempld_read8(pld, KEMPLD_I2C_STAT);
 278         if (stat & I2C_STAT_BUSY)
 279                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 280 }
 281
 282 static u32 kempld_i2c_func(struct i2c_adapter *adap)
 283 {
 284         return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
 285 }
 286
 287 static const struct i2c_algorithm kempld_i2c_algorithm = {
 288         .master_xfer    = kempld_i2c_xfer,
 289         .functionality  = kempld_i2c_func,
 290 };
 291
 292 static struct i2c_adapter kempld_i2c_adapter = {
 293         .owner          = THIS_MODULE,
 294         .name           = "i2c-kempld",
 295         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 296         .algo           = &kempld_i2c_algorithm,
 297 };
 298
 299 static int kempld_i2c_probe(struct platform_device *pdev)
 300 {
 301         struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
 302         struct kempld_i2c_data *i2c;
 303         int ret;
 304         u8 ctrl;
 305
 306         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 307         if (!i2c)
 308                 return -ENOMEM;
 309
 310         i2c->pld = pld;
 311         i2c->dev = &pdev->dev;
 312         i2c->adap = kempld_i2c_adapter;
 313         i2c->adap.dev.parent = i2c->dev;
 314         i2c_set_adapdata(&i2c->adap, i2c);
 315         platform_set_drvdata(pdev, i2c);
 316
 317         kempld_get_mutex(pld);
 318         ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 319
 320         if (ctrl & I2C_CTRL_EN)
 321                 i2c->was_active = true;
 322
 323         kempld_i2c_device_init(i2c);
 324         kempld_release_mutex(pld);
 325
 326         /* Add I2C adapter to I2C tree */
 327         if (i2c_bus >= -1)
 328                 i2c->adap.nr = i2c_bus;
 329         ret = i2c_add_numbered_adapter(&i2c->adap);
 330         if (ret)
 331                 return ret;
 332
 333         dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
 334                  bus_frequency);
 335
 336         return 0;
 337 }
 338
 339 static int kempld_i2c_remove(struct platform_device *pdev)
 340 {
 341         struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 342         struct kempld_device_data *pld = i2c->pld;
 343         u8 ctrl;
 344
 345         kempld_get_mutex(pld);
 346         /*
 347          * Disable I2C logic if it was not activated before the
 348          * driver loaded
 349          */
 350         if (!i2c->was_active) {
 351                 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 352                 ctrl &= ~I2C_CTRL_EN;
 353                 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 354         }
 355         kempld_release_mutex(pld);
 356
 357         i2c_del_adapter(&i2c->adap);
 358
 359         return 0;
 360 }
 361
 362 #ifdef CONFIG_PM
 363 static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
 364 {
 365         struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 366         struct kempld_device_data *pld = i2c->pld;
 367         u8 ctrl;
 368
 369         kempld_get_mutex(pld);
 370         ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 371         ctrl &= ~I2C_CTRL_EN;
 372         kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 373         kempld_release_mutex(pld);
 374
 375         return 0;
 376 }
 377
 378 static int kempld_i2c_resume(struct platform_device *pdev)
 379 {
 380         struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 381         struct kempld_device_data *pld = i2c->pld;
 382
 383         kempld_get_mutex(pld);
 384         kempld_i2c_device_init(i2c);
 385         kempld_release_mutex(pld);
 386
 387         return 0;
 388 }
 389 #else
 390 #define kempld_i2c_suspend      NULL
 391 #define kempld_i2c_resume       NULL
 392 #endif
 393
 394 static struct platform_driver kempld_i2c_driver = {
 395         .driver = {
 396                 .name = "kempld-i2c",
 397         },
 398         .probe          = kempld_i2c_probe,
 399         .remove         = kempld_i2c_remove,
 400         .suspend        = kempld_i2c_suspend,
 401         .resume         = kempld_i2c_resume,
 402 };
 403
 404 module_platform_driver(kempld_i2c_driver);
 405
 406 MODULE_DESCRIPTION("KEM PLD I2C Driver");
 407 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 408 MODULE_LICENSE("GPL");
 409 MODULE_ALIAS("platform:kempld_i2c");