drivers/i2c/busses/i2c-ocores.c

   1 /*
   2  * i2c-ocores.c: I2C bus driver for OpenCores I2C controller
   3  * (http://www.opencores.org/projects.cgi/web/i2c/overview).
   4  *
   5  * Peter Korsgaard <jacmet@sunsite.dk>
   6  *
   7  * This file is licensed under the terms of the GNU General Public License
   8  * version 2.  This program is licensed "as is" without any warranty of any
   9  * kind, whether express or implied.
  10  */
  11
  12 /*
  13  * Device tree configuration:
  14  *
  15  * Required properties:
  16  * - compatible      : "opencores,i2c-ocores"
  17  * - reg             : bus address start and address range size of device
  18  * - interrupts      : interrupt number
  19  * - regstep         : size of device registers in bytes
  20  * - clock-frequency : frequency of bus clock in Hz
  21  *
  22  * Example:
  23  *
  24  *  i2c0: ocores@a0000000 {
  25  *              compatible = "opencores,i2c-ocores";
  26  *              reg = <0xa0000000 0x8>;
  27  *              interrupts = <10>;
  28  *
  29  *              regstep = <1>;
  30  *              clock-frequency = <20000000>;
  31  *
  32  * -- Devices connected on this I2C bus get
  33  * -- defined here; address- and size-cells
  34  * -- apply to these child devices
  35  *
  36  *              #address-cells = <1>;
  37  *              #size-cells = <0>;
  38  *
  39  *              dummy@60 {
  40  *                     compatible = "dummy";
  41  *                     reg = <60>;
  42  *              };
  43  *  };
  44  *
  45  */
  46
  47 #include <linux/kernel.h>
  48 #include <linux/module.h>
  49 #include <linux/init.h>
  50 #include <linux/errno.h>
  51 #include <linux/platform_device.h>
  52 #include <linux/i2c.h>
  53 #include <linux/interrupt.h>
  54 #include <linux/wait.h>
  55 #include <linux/i2c-ocores.h>
  56 #include <linux/slab.h>
  57 #include <linux/io.h>
  58
  59 struct ocores_i2c {
  60         void __iomem *base;
  61         int regstep;
  62         wait_queue_head_t wait;
  63         struct i2c_adapter adap;
  64         struct i2c_msg *msg;
  65         int pos;
  66         int nmsgs;
  67         int state; /* see STATE_ */
  68         int clock_khz;
  69 };
  70
  71 /* registers */
  72 #define OCI2C_PRELOW            0
  73 #define OCI2C_PREHIGH           1
  74 #define OCI2C_CONTROL           2
  75 #define OCI2C_DATA              3
  76 #define OCI2C_CMD               4 /* write only */
  77 #define OCI2C_STATUS            4 /* read only, same address as OCI2C_CMD */
  78
  79 #define OCI2C_CTRL_IEN          0x40
  80 #define OCI2C_CTRL_EN           0x80
  81
  82 #define OCI2C_CMD_START         0x91
  83 #define OCI2C_CMD_STOP          0x41
  84 #define OCI2C_CMD_READ          0x21
  85 #define OCI2C_CMD_WRITE         0x11
  86 #define OCI2C_CMD_READ_ACK      0x21
  87 #define OCI2C_CMD_READ_NACK     0x29
  88 #define OCI2C_CMD_IACK          0x01
  89
  90 #define OCI2C_STAT_IF           0x01
  91 #define OCI2C_STAT_TIP          0x02
  92 #define OCI2C_STAT_ARBLOST      0x20
  93 #define OCI2C_STAT_BUSY         0x40
  94 #define OCI2C_STAT_NACK         0x80
  95
  96 #define STATE_DONE              0
  97 #define STATE_START             1
  98 #define STATE_WRITE             2
  99 #define STATE_READ              3
 100 #define STATE_ERROR             4
 101
 102 static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
 103 {
 104         iowrite8(value, i2c->base + reg * i2c->regstep);
 105 }
 106
 107 static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
 108 {
 109         return ioread8(i2c->base + reg * i2c->regstep);
 110 }
 111
 112 static void ocores_process(struct ocores_i2c *i2c)
 113 {
 114         struct i2c_msg *msg = i2c->msg;
 115         u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 116
 117         if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
 118                 /* stop has been sent */
 119                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
 120                 wake_up(&i2c->wait);
 121                 return;
 122         }
 123
 124         /* error? */
 125         if (stat & OCI2C_STAT_ARBLOST) {
 126                 i2c->state = STATE_ERROR;
 127                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 128                 return;
 129         }
 130
 131         if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) {
 132                 i2c->state =
 133                         (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 134
 135                 if (stat & OCI2C_STAT_NACK) {
 136                         i2c->state = STATE_ERROR;
 137                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 138                         return;
 139                 }
 140         } else
 141                 msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
 142
 143         /* end of msg? */
 144         if (i2c->pos == msg->len) {
 145                 i2c->nmsgs--;
 146                 i2c->msg++;
 147                 i2c->pos = 0;
 148                 msg = i2c->msg;
 149
 150                 if (i2c->nmsgs) {       /* end? */
 151                         /* send start? */
 152                         if (!(msg->flags & I2C_M_NOSTART)) {
 153                                 u8 addr = (msg->addr << 1);
 154
 155                                 if (msg->flags & I2C_M_RD)
 156                                         addr |= 1;
 157
 158                                 i2c->state = STATE_START;
 159
 160                                 oc_setreg(i2c, OCI2C_DATA, addr);
 161                                 oc_setreg(i2c, OCI2C_CMD,  OCI2C_CMD_START);
 162                                 return;
 163                         } else
 164                                 i2c->state = (msg->flags & I2C_M_RD)
 165                                         ? STATE_READ : STATE_WRITE;
 166                 } else {
 167                         i2c->state = STATE_DONE;
 168                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 169                         return;
 170                 }
 171         }
 172
 173         if (i2c->state == STATE_READ) {
 174                 oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ?
 175                           OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK);
 176         } else {
 177                 oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]);
 178                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE);
 179         }
 180 }
 181
 182 static irqreturn_t ocores_isr(int irq, void *dev_id)
 183 {
 184         struct ocores_i2c *i2c = dev_id;
 185
 186         ocores_process(i2c);
 187
 188         return IRQ_HANDLED;
 189 }
 190
 191 static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 192 {
 193         struct ocores_i2c *i2c = i2c_get_adapdata(adap);
 194
 195         i2c->msg = msgs;
 196         i2c->pos = 0;
 197         i2c->nmsgs = num;
 198         i2c->state = STATE_START;
 199
 200         oc_setreg(i2c, OCI2C_DATA,
 201                         (i2c->msg->addr << 1) |
 202                         ((i2c->msg->flags & I2C_M_RD) ? 1:0));
 203
 204         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
 205
 206         if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
 207                                (i2c->state == STATE_DONE), HZ))
 208                 return (i2c->state == STATE_DONE) ? num : -EIO;
 209         else
 210                 return -ETIMEDOUT;
 211 }
 212
 213 static void ocores_init(struct ocores_i2c *i2c)
 214 {
 215         int prescale;
 216         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
 217
 218         /* make sure the device is disabled */
 219         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 220
 221         prescale = (i2c->clock_khz / (5*100)) - 1;
 222         oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
 223         oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
 224
 225         /* Init the device */
 226         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
 227         oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
 228 }
 229
 230
 231 static u32 ocores_func(struct i2c_adapter *adap)
 232 {
 233         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 234 }
 235
 236 static const struct i2c_algorithm ocores_algorithm = {
 237         .master_xfer    = ocores_xfer,
 238         .functionality  = ocores_func,
 239 };
 240
 241 static struct i2c_adapter ocores_adapter = {
 242         .owner          = THIS_MODULE,
 243         .name           = "i2c-ocores",
 244         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 245         .algo           = &ocores_algorithm,
 246 };
 247
 248 #ifdef CONFIG_OF
 249 static int ocores_i2c_of_probe(struct platform_device* pdev,
 250                                 struct ocores_i2c* i2c)
 251 {
 252         const __be32* val;
 253
 254         val = of_get_property(pdev->dev.of_node, "regstep", NULL);
 255         if (!val) {
 256                 dev_err(&pdev->dev, "Missing required parameter 'regstep'");
 257                 return -ENODEV;
 258         }
 259         i2c->regstep = be32_to_cpup(val);
 260
 261         val = of_get_property(pdev->dev.of_node, "clock-frequency", NULL);
 262         if (!val) {
 263                 dev_err(&pdev->dev,
 264                         "Missing required parameter 'clock-frequency'");
 265                 return -ENODEV;
 266         }
 267         i2c->clock_khz = be32_to_cpup(val) / 1000;
 268
 269         return 0;
 270 }
 271 #else
 272 #define ocores_i2c_of_probe(pdev,i2c) -ENODEV
 273 #endif
 274
 275 static int __devinit ocores_i2c_probe(struct platform_device *pdev)
 276 {
 277         struct ocores_i2c *i2c;
 278         struct ocores_i2c_platform_data *pdata;
 279         struct resource *res, *res2;
 280         int ret;
 281         int i;
 282
 283         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 284         if (!res)
 285                 return -ENODEV;
 286
 287         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 288         if (!res2)
 289                 return -ENODEV;
 290
 291         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 292         if (!i2c)
 293                 return -ENOMEM;
 294
 295         if (!devm_request_mem_region(&pdev->dev, res->start,
 296                                      resource_size(res), pdev->name)) {
 297                 dev_err(&pdev->dev, "Memory region busy\n");
 298                 return -EBUSY;
 299         }
 300
 301         i2c->base = devm_ioremap_nocache(&pdev->dev, res->start,
 302                                          resource_size(res));
 303         if (!i2c->base) {
 304                 dev_err(&pdev->dev, "Unable to map registers\n");
 305                 return -EIO;
 306         }
 307
 308         pdata = pdev->dev.platform_data;
 309         if (pdata) {
 310                 i2c->regstep = pdata->regstep;
 311                 i2c->clock_khz = pdata->clock_khz;
 312         } else {
 313                 ret = ocores_i2c_of_probe(pdev, i2c);
 314                 if (ret)
 315                         return ret;
 316         }
 317
 318         ocores_init(i2c);
 319
 320         init_waitqueue_head(&i2c->wait);
 321         ret = devm_request_irq(&pdev->dev, res2->start, ocores_isr, 0,
 322                                pdev->name, i2c);
 323         if (ret) {
 324                 dev_err(&pdev->dev, "Cannot claim IRQ\n");
 325                 return ret;
 326         }
 327
 328         /* hook up driver to tree */
 329         platform_set_drvdata(pdev, i2c);
 330         i2c->adap = ocores_adapter;
 331         i2c_set_adapdata(&i2c->adap, i2c);
 332         i2c->adap.dev.parent = &pdev->dev;
 333 #ifdef CONFIG_OF
 334         i2c->adap.dev.of_node = pdev->dev.of_node;
 335 #endif
 336
 337         /* add i2c adapter to i2c tree */
 338         ret = i2c_add_adapter(&i2c->adap);
 339         if (ret) {
 340                 dev_err(&pdev->dev, "Failed to add adapter\n");
 341                 return ret;
 342         }
 343
 344         /* add in known devices to the bus */
 345         if (pdata) {
 346                 for (i = 0; i < pdata->num_devices; i++)
 347                         i2c_new_device(&i2c->adap, pdata->devices + i);
 348         }
 349
 350         return 0;
 351 }
 352
 353 static int __devexit ocores_i2c_remove(struct platform_device* pdev)
 354 {
 355         struct ocores_i2c *i2c = platform_get_drvdata(pdev);
 356
 357         /* disable i2c logic */
 358         oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL)
 359                   & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 360
 361         /* remove adapter & data */
 362         i2c_del_adapter(&i2c->adap);
 363         platform_set_drvdata(pdev, NULL);
 364
 365         return 0;
 366 }
 367
 368 #ifdef CONFIG_PM
 369 static int ocores_i2c_suspend(struct platform_device *pdev, pm_message_t state)
 370 {
 371         struct ocores_i2c *i2c = platform_get_drvdata(pdev);
 372         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
 373
 374         /* make sure the device is disabled */
 375         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 376
 377         return 0;
 378 }
 379
 380 static int ocores_i2c_resume(struct platform_device *pdev)
 381 {
 382         struct ocores_i2c *i2c = platform_get_drvdata(pdev);
 383
 384         ocores_init(i2c);
 385
 386         return 0;
 387 }
 388 #else
 389 #define ocores_i2c_suspend      NULL
 390 #define ocores_i2c_resume       NULL
 391 #endif
 392
 393 #ifdef CONFIG_OF
 394 static struct of_device_id ocores_i2c_match[] = {
 395         {
 396                 .compatible = "opencores,i2c-ocores",
 397         },
 398         {},
 399 };
 400 MODULE_DEVICE_TABLE(of, ocores_i2c_match);
 401 #endif
 402
 403 /* work with hotplug and coldplug */
 404 MODULE_ALIAS("platform:ocores-i2c");
 405
 406 static struct platform_driver ocores_i2c_driver = {
 407         .probe   = ocores_i2c_probe,
 408         .remove  = __devexit_p(ocores_i2c_remove),
 409         .suspend = ocores_i2c_suspend,
 410         .resume  = ocores_i2c_resume,
 411         .driver  = {
 412                 .owner = THIS_MODULE,
 413                 .name = "ocores-i2c",
 414 #ifdef CONFIG_OF
 415                 .of_match_table = ocores_i2c_match,
 416 #endif
 417         },
 418 };
 419
 420 static int __init ocores_i2c_init(void)
 421 {
 422         return platform_driver_register(&ocores_i2c_driver);
 423 }
 424
 425 static void __exit ocores_i2c_exit(void)
 426 {
 427         platform_driver_unregister(&ocores_i2c_driver);
 428 }
 429
 430 module_init(ocores_i2c_init);
 431 module_exit(ocores_i2c_exit);
 432
 433 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 434 MODULE_DESCRIPTION("OpenCores I2C bus driver");
 435 MODULE_LICENSE("GPL");