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