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  * This driver can be used from the device tree, see
  14  *     Documentation/devicetree/bindings/i2c/ocore-i2c.txt
  15  */
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19 #include <linux/errno.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/i2c.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/wait.h>
  24 #include <linux/i2c-ocores.h>
  25 #include <linux/slab.h>
  26 #include <linux/io.h>
  27 #include <linux/of_i2c.h>
  28 #include <linux/log2.h>
  29
  30 struct ocores_i2c {
  31         void __iomem *base;
  32         u32 reg_shift;
  33         u32 reg_io_width;
  34         wait_queue_head_t wait;
  35         struct i2c_adapter adap;
  36         struct i2c_msg *msg;
  37         int pos;
  38         int nmsgs;
  39         int state; /* see STATE_ */
  40         int clock_khz;
  41 };
  42
  43 /* registers */
  44 #define OCI2C_PRELOW            0
  45 #define OCI2C_PREHIGH           1
  46 #define OCI2C_CONTROL           2
  47 #define OCI2C_DATA              3
  48 #define OCI2C_CMD               4 /* write only */
  49 #define OCI2C_STATUS            4 /* read only, same address as OCI2C_CMD */
  50
  51 #define OCI2C_CTRL_IEN          0x40
  52 #define OCI2C_CTRL_EN           0x80
  53
  54 #define OCI2C_CMD_START         0x91
  55 #define OCI2C_CMD_STOP          0x41
  56 #define OCI2C_CMD_READ          0x21
  57 #define OCI2C_CMD_WRITE         0x11
  58 #define OCI2C_CMD_READ_ACK      0x21
  59 #define OCI2C_CMD_READ_NACK     0x29
  60 #define OCI2C_CMD_IACK          0x01
  61
  62 #define OCI2C_STAT_IF           0x01
  63 #define OCI2C_STAT_TIP          0x02
  64 #define OCI2C_STAT_ARBLOST      0x20
  65 #define OCI2C_STAT_BUSY         0x40
  66 #define OCI2C_STAT_NACK         0x80
  67
  68 #define STATE_DONE              0
  69 #define STATE_START             1
  70 #define STATE_WRITE             2
  71 #define STATE_READ              3
  72 #define STATE_ERROR             4
  73
  74 static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
  75 {
  76         if (i2c->reg_io_width == 4)
  77                 iowrite32(value, i2c->base + (reg << i2c->reg_shift));
  78         else if (i2c->reg_io_width == 2)
  79                 iowrite16(value, i2c->base + (reg << i2c->reg_shift));
  80         else
  81                 iowrite8(value, i2c->base + (reg << i2c->reg_shift));
  82 }
  83
  84 static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
  85 {
  86         if (i2c->reg_io_width == 4)
  87                 return ioread32(i2c->base + (reg << i2c->reg_shift));
  88         else if (i2c->reg_io_width == 2)
  89                 return ioread16(i2c->base + (reg << i2c->reg_shift));
  90         else
  91                 return ioread8(i2c->base + (reg << i2c->reg_shift));
  92 }
  93
  94 static void ocores_process(struct ocores_i2c *i2c)
  95 {
  96         struct i2c_msg *msg = i2c->msg;
  97         u8 stat = oc_getreg(i2c, OCI2C_STATUS);
  98
  99         if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
 100                 /* stop has been sent */
 101                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
 102                 wake_up(&i2c->wait);
 103                 return;
 104         }
 105
 106         /* error? */
 107         if (stat & OCI2C_STAT_ARBLOST) {
 108                 i2c->state = STATE_ERROR;
 109                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 110                 return;
 111         }
 112
 113         if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) {
 114                 i2c->state =
 115                         (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 116
 117                 if (stat & OCI2C_STAT_NACK) {
 118                         i2c->state = STATE_ERROR;
 119                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 120                         return;
 121                 }
 122         } else
 123                 msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
 124
 125         /* end of msg? */
 126         if (i2c->pos == msg->len) {
 127                 i2c->nmsgs--;
 128                 i2c->msg++;
 129                 i2c->pos = 0;
 130                 msg = i2c->msg;
 131
 132                 if (i2c->nmsgs) {       /* end? */
 133                         /* send start? */
 134                         if (!(msg->flags & I2C_M_NOSTART)) {
 135                                 u8 addr = (msg->addr << 1);
 136
 137                                 if (msg->flags & I2C_M_RD)
 138                                         addr |= 1;
 139
 140                                 i2c->state = STATE_START;
 141
 142                                 oc_setreg(i2c, OCI2C_DATA, addr);
 143                                 oc_setreg(i2c, OCI2C_CMD,  OCI2C_CMD_START);
 144                                 return;
 145                         } else
 146                                 i2c->state = (msg->flags & I2C_M_RD)
 147                                         ? STATE_READ : STATE_WRITE;
 148                 } else {
 149                         i2c->state = STATE_DONE;
 150                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 151                         return;
 152                 }
 153         }
 154
 155         if (i2c->state == STATE_READ) {
 156                 oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ?
 157                           OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK);
 158         } else {
 159                 oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]);
 160                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE);
 161         }
 162 }
 163
 164 static irqreturn_t ocores_isr(int irq, void *dev_id)
 165 {
 166         struct ocores_i2c *i2c = dev_id;
 167
 168         ocores_process(i2c);
 169
 170         return IRQ_HANDLED;
 171 }
 172
 173 static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 174 {
 175         struct ocores_i2c *i2c = i2c_get_adapdata(adap);
 176
 177         i2c->msg = msgs;
 178         i2c->pos = 0;
 179         i2c->nmsgs = num;
 180         i2c->state = STATE_START;
 181
 182         oc_setreg(i2c, OCI2C_DATA,
 183                         (i2c->msg->addr << 1) |
 184                         ((i2c->msg->flags & I2C_M_RD) ? 1:0));
 185
 186         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
 187
 188         if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
 189                                (i2c->state == STATE_DONE), HZ))
 190                 return (i2c->state == STATE_DONE) ? num : -EIO;
 191         else
 192                 return -ETIMEDOUT;
 193 }
 194
 195 static void ocores_init(struct ocores_i2c *i2c)
 196 {
 197         int prescale;
 198         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
 199
 200         /* make sure the device is disabled */
 201         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 202
 203         prescale = (i2c->clock_khz / (5*100)) - 1;
 204         oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
 205         oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
 206
 207         /* Init the device */
 208         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
 209         oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
 210 }
 211
 212
 213 static u32 ocores_func(struct i2c_adapter *adap)
 214 {
 215         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 216 }
 217
 218 static const struct i2c_algorithm ocores_algorithm = {
 219         .master_xfer    = ocores_xfer,
 220         .functionality  = ocores_func,
 221 };
 222
 223 static struct i2c_adapter ocores_adapter = {
 224         .owner          = THIS_MODULE,
 225         .name           = "i2c-ocores",
 226         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 227         .algo           = &ocores_algorithm,
 228 };
 229
 230 #ifdef CONFIG_OF
 231 static int ocores_i2c_of_probe(struct platform_device *pdev,
 232                                 struct ocores_i2c *i2c)
 233 {
 234         struct device_node *np = pdev->dev.of_node;
 235         u32 val;
 236
 237         if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) {
 238                 /* no 'reg-shift', check for deprecated 'regstep' */
 239                 if (!of_property_read_u32(np, "regstep", &val)) {
 240                         if (!is_power_of_2(val)) {
 241                                 dev_err(&pdev->dev, "invalid regstep %d\n",
 242                                         val);
 243                                 return -EINVAL;
 244                         }
 245                         i2c->reg_shift = ilog2(val);
 246                         dev_warn(&pdev->dev,
 247                                 "regstep property deprecated, use reg-shift\n");
 248                 }
 249         }
 250
 251         if (of_property_read_u32(np, "clock-frequency", &val)) {
 252                 dev_err(&pdev->dev,
 253                         "Missing required parameter 'clock-frequency'\n");
 254                 return -ENODEV;
 255         }
 256         i2c->clock_khz = val / 1000;
 257
 258         of_property_read_u32(pdev->dev.of_node, "reg-io-width",
 259                                 &i2c->reg_io_width);
 260         return 0;
 261 }
 262 #else
 263 #define ocores_i2c_of_probe(pdev,i2c) -ENODEV
 264 #endif
 265
 266 static int __devinit ocores_i2c_probe(struct platform_device *pdev)
 267 {
 268         struct ocores_i2c *i2c;
 269         struct ocores_i2c_platform_data *pdata;
 270         struct resource *res, *res2;
 271         int ret;
 272         int i;
 273
 274         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 275         if (!res)
 276                 return -ENODEV;
 277
 278         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 279         if (!res2)
 280                 return -ENODEV;
 281
 282         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 283         if (!i2c)
 284                 return -ENOMEM;
 285
 286         if (!devm_request_mem_region(&pdev->dev, res->start,
 287                                      resource_size(res), pdev->name)) {
 288                 dev_err(&pdev->dev, "Memory region busy\n");
 289                 return -EBUSY;
 290         }
 291
 292         i2c->base = devm_ioremap_nocache(&pdev->dev, res->start,
 293                                          resource_size(res));
 294         if (!i2c->base) {
 295                 dev_err(&pdev->dev, "Unable to map registers\n");
 296                 return -EIO;
 297         }
 298
 299         pdata = pdev->dev.platform_data;
 300         if (pdata) {
 301                 i2c->reg_shift = pdata->reg_shift;
 302                 i2c->reg_io_width = pdata->reg_io_width;
 303                 i2c->clock_khz = pdata->clock_khz;
 304         } else {
 305                 ret = ocores_i2c_of_probe(pdev, i2c);
 306                 if (ret)
 307                         return ret;
 308         }
 309
 310         if (i2c->reg_io_width == 0)
 311                 i2c->reg_io_width = 1; /* Set to default value */
 312
 313         ocores_init(i2c);
 314
 315         init_waitqueue_head(&i2c->wait);
 316         ret = devm_request_irq(&pdev->dev, res2->start, ocores_isr, 0,
 317                                pdev->name, i2c);
 318         if (ret) {
 319                 dev_err(&pdev->dev, "Cannot claim IRQ\n");
 320                 return ret;
 321         }
 322
 323         /* hook up driver to tree */
 324         platform_set_drvdata(pdev, i2c);
 325         i2c->adap = ocores_adapter;
 326         i2c_set_adapdata(&i2c->adap, i2c);
 327         i2c->adap.dev.parent = &pdev->dev;
 328         i2c->adap.dev.of_node = pdev->dev.of_node;
 329
 330         /* add i2c adapter to i2c tree */
 331         ret = i2c_add_adapter(&i2c->adap);
 332         if (ret) {
 333                 dev_err(&pdev->dev, "Failed to add adapter\n");
 334                 return ret;
 335         }
 336
 337         /* add in known devices to the bus */
 338         if (pdata) {
 339                 for (i = 0; i < pdata->num_devices; i++)
 340                         i2c_new_device(&i2c->adap, pdata->devices + i);
 341         } else {
 342                 of_i2c_register_devices(&i2c->adap);
 343         }
 344
 345         return 0;
 346 }
 347
 348 static int __devexit ocores_i2c_remove(struct platform_device *pdev)
 349 {
 350         struct ocores_i2c *i2c = platform_get_drvdata(pdev);
 351
 352         /* disable i2c logic */
 353         oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL)
 354                   & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 355
 356         /* remove adapter & data */
 357         i2c_del_adapter(&i2c->adap);
 358         platform_set_drvdata(pdev, NULL);
 359
 360         return 0;
 361 }
 362
 363 #ifdef CONFIG_PM
 364 static int ocores_i2c_suspend(struct device *dev)
 365 {
 366         struct ocores_i2c *i2c = dev_get_drvdata(dev);
 367         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
 368
 369         /* make sure the device is disabled */
 370         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 371
 372         return 0;
 373 }
 374
 375 static int ocores_i2c_resume(struct device *dev)
 376 {
 377         struct ocores_i2c *i2c = dev_get_drvdata(dev);
 378
 379         ocores_init(i2c);
 380
 381         return 0;
 382 }
 383
 384 static SIMPLE_DEV_PM_OPS(ocores_i2c_pm, ocores_i2c_suspend, ocores_i2c_resume);
 385 #define OCORES_I2C_PM   (&ocores_i2c_pm)
 386 #else
 387 #define OCORES_I2C_PM   NULL
 388 #endif
 389
 390 static struct of_device_id ocores_i2c_match[] = {
 391         { .compatible = "opencores,i2c-ocores", },
 392         {},
 393 };
 394 MODULE_DEVICE_TABLE(of, ocores_i2c_match);
 395
 396 static struct platform_driver ocores_i2c_driver = {
 397         .probe   = ocores_i2c_probe,
 398         .remove  = __devexit_p(ocores_i2c_remove),
 399         .driver  = {
 400                 .owner = THIS_MODULE,
 401                 .name = "ocores-i2c",
 402                 .of_match_table = ocores_i2c_match,
 403                 .pm = OCORES_I2C_PM,
 404         },
 405 };
 406
 407 module_platform_driver(ocores_i2c_driver);
 408
 409 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 410 MODULE_DESCRIPTION("OpenCores I2C bus driver");
 411 MODULE_LICENSE("GPL");
 412 MODULE_ALIAS("platform:ocores-i2c");