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