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