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                         /* Set read bit if necessary */
 128                         addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
 129                         i2c->state = STATE_ADDR10;
 130                 } else {
 131                         addr = i2c_8bit_addr_from_msg(i2c->msg);
 132                         i2c->state = STATE_START;
 133                 }
 134
 135                 kempld_write8(pld, KEMPLD_I2C_DATA, addr);
 136                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
 137
 138                 return 0;
 139         }
 140
 141         /* Second part of 10 bit addressing */
 142         if (i2c->state == STATE_ADDR10) {
 143                 kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
 144                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
 145
 146                 i2c->state = STATE_START;
 147                 return 0;
 148         }
 149
 150         if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
 151                 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 152
 153                 if (stat & I2C_STAT_NACK) {
 154                         i2c->state = STATE_ERROR;
 155                         kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 156                         return -ENXIO;
 157                 }
 158         } else {
 159                 msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
 160         }
 161
 162         if (i2c->pos >= msg->len) {
 163                 i2c->nmsgs--;
 164                 i2c->msg++;
 165                 i2c->pos = 0;
 166                 msg = i2c->msg;
 167
 168                 if (i2c->nmsgs) {
 169                         if (!(msg->flags & I2C_M_NOSTART)) {
 170                                 i2c->state = STATE_ADDR;
 171                                 return 0;
 172                         } else {
 173                                 i2c->state = (msg->flags & I2C_M_RD)
 174                                         ? STATE_READ : STATE_WRITE;
 175                         }
 176                 } else {
 177                         i2c->state = STATE_DONE;
 178                         kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 179                         return 0;
 180                 }
 181         }
 182
 183         if (i2c->state == STATE_READ) {
 184                 kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
 185                               I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
 186         } else {
 187                 kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
 188                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
 189         }
 190
 191         return 0;
 192 }
 193
 194 static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 195                                 int num)
 196 {
 197         struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
 198         struct kempld_device_data *pld = i2c->pld;
 199         unsigned long timeout = jiffies + HZ;
 200         int ret;
 201
 202         i2c->msg = msgs;
 203         i2c->pos = 0;
 204         i2c->nmsgs = num;
 205         i2c->state = STATE_INIT;
 206
 207         /* Handle the transfer */
 208         while (time_before(jiffies, timeout)) {
 209                 kempld_get_mutex(pld);
 210                 ret = kempld_i2c_process(i2c);
 211                 kempld_release_mutex(pld);
 212
 213                 if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
 214                         return (i2c->state == STATE_DONE) ? num : ret;
 215
 216                 if (ret == 0)
 217                         timeout = jiffies + HZ;
 218
 219                 usleep_range(5, 15);
 220         }
 221
 222         i2c->state = STATE_ERROR;
 223
 224         return -ETIMEDOUT;
 225 }
 226
 227 /*
 228  * kempld_get_mutex must be called prior to calling this function.
 229  */
 230 static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
 231 {
 232         struct kempld_device_data *pld = i2c->pld;
 233         u16 prescale_corr;
 234         long prescale;
 235         u8 ctrl;
 236         u8 stat;
 237         u8 cfg;
 238
 239         /* Make sure the device is disabled */
 240         ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 241         ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
 242         kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 243
 244         if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
 245                 bus_frequency = KEMPLD_I2C_FREQ_MAX;
 246
 247         if (pld->info.spec_major == 1)
 248                 prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
 249         else
 250                 prescale = pld->pld_clock / (bus_frequency * 4) - 3000;
 251
 252         if (prescale < 0)
 253                 prescale = 0;
 254
 255         /* Round to the best matching value */
 256         prescale_corr = prescale / 1000;
 257         if (prescale % 1000 >= 500)
 258                 prescale_corr++;
 259
 260         kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
 261         kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
 262
 263         /* Activate I2C bus output on GPIO pins */
 264         cfg = kempld_read8(pld, KEMPLD_CFG);
 265         if (i2c_gpio_mux)
 266                 cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
 267         else
 268                 cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
 269         kempld_write8(pld, KEMPLD_CFG, cfg);
 270
 271         /* Enable the device */
 272         kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
 273         ctrl |= I2C_CTRL_EN;
 274         kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 275
 276         stat = kempld_read8(pld, KEMPLD_I2C_STAT);
 277         if (stat & I2C_STAT_BUSY)
 278                 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 279 }
 280
 281 static u32 kempld_i2c_func(struct i2c_adapter *adap)
 282 {
 283         return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
 284 }
 285
 286 static const struct i2c_algorithm kempld_i2c_algorithm = {
 287         .master_xfer    = kempld_i2c_xfer,
 288         .functionality  = kempld_i2c_func,
 289 };
 290
 291 static const struct i2c_adapter kempld_i2c_adapter = {
 292         .owner          = THIS_MODULE,
 293         .name           = "i2c-kempld",
 294         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 295         .algo           = &kempld_i2c_algorithm,
 296 };
 297
 298 static int kempld_i2c_probe(struct platform_device *pdev)
 299 {
 300         struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
 301         struct kempld_i2c_data *i2c;
 302         int ret;
 303         u8 ctrl;
 304
 305         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 306         if (!i2c)
 307                 return -ENOMEM;
 308
 309         i2c->pld = pld;
 310         i2c->dev = &pdev->dev;
 311         i2c->adap = kempld_i2c_adapter;
 312         i2c->adap.dev.parent = i2c->dev;
 313         i2c_set_adapdata(&i2c->adap, i2c);
 314         platform_set_drvdata(pdev, i2c);
 315
 316         kempld_get_mutex(pld);
 317         ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 318
 319         if (ctrl & I2C_CTRL_EN)
 320                 i2c->was_active = true;
 321
 322         kempld_i2c_device_init(i2c);
 323         kempld_release_mutex(pld);
 324
 325         /* Add I2C adapter to I2C tree */
 326         if (i2c_bus >= -1)
 327                 i2c->adap.nr = i2c_bus;
 328         ret = i2c_add_numbered_adapter(&i2c->adap);
 329         if (ret)
 330                 return ret;
 331
 332         dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
 333                  bus_frequency);
 334
 335         return 0;
 336 }
 337
 338 static int kempld_i2c_remove(struct platform_device *pdev)
 339 {
 340         struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 341         struct kempld_device_data *pld = i2c->pld;
 342         u8 ctrl;
 343
 344         kempld_get_mutex(pld);
 345         /*
 346          * Disable I2C logic if it was not activated before the
 347          * driver loaded
 348          */
 349         if (!i2c->was_active) {
 350                 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 351                 ctrl &= ~I2C_CTRL_EN;
 352                 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 353         }
 354         kempld_release_mutex(pld);
 355
 356         i2c_del_adapter(&i2c->adap);
 357
 358         return 0;
 359 }
 360
 361 #ifdef CONFIG_PM
 362 static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
 363 {
 364         struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 365         struct kempld_device_data *pld = i2c->pld;
 366         u8 ctrl;
 367
 368         kempld_get_mutex(pld);
 369         ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 370         ctrl &= ~I2C_CTRL_EN;
 371         kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 372         kempld_release_mutex(pld);
 373
 374         return 0;
 375 }
 376
 377 static int kempld_i2c_resume(struct platform_device *pdev)
 378 {
 379         struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 380         struct kempld_device_data *pld = i2c->pld;
 381
 382         kempld_get_mutex(pld);
 383         kempld_i2c_device_init(i2c);
 384         kempld_release_mutex(pld);
 385
 386         return 0;
 387 }
 388 #else
 389 #define kempld_i2c_suspend      NULL
 390 #define kempld_i2c_resume       NULL
 391 #endif
 392
 393 static struct platform_driver kempld_i2c_driver = {
 394         .driver = {
 395                 .name = "kempld-i2c",
 396         },
 397         .probe          = kempld_i2c_probe,
 398         .remove         = kempld_i2c_remove,
 399         .suspend        = kempld_i2c_suspend,
 400         .resume         = kempld_i2c_resume,
 401 };
 402
 403 module_platform_driver(kempld_i2c_driver);
 404
 405 MODULE_DESCRIPTION("KEM PLD I2C Driver");
 406 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 407 MODULE_LICENSE("GPL");
 408 MODULE_ALIAS("platform:kempld_i2c");