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