drivers/i2c/busses/i2c-efm32.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2014 Uwe Kleine-Koenig for Pengutronix
   4  */
   5 #include <linux/module.h>
   6 #include <linux/platform_device.h>
   7 #include <linux/i2c.h>
   8 #include <linux/io.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/err.h>
  11 #include <linux/clk.h>
  12
  13 #define DRIVER_NAME "efm32-i2c"
  14
  15 #define MASK_VAL(mask, val)             ((val << __ffs(mask)) & mask)
  16
  17 #define REG_CTRL                0x00
  18 #define REG_CTRL_EN                     0x00001
  19 #define REG_CTRL_SLAVE                  0x00002
  20 #define REG_CTRL_AUTOACK                0x00004
  21 #define REG_CTRL_AUTOSE                 0x00008
  22 #define REG_CTRL_AUTOSN                 0x00010
  23 #define REG_CTRL_ARBDIS                 0x00020
  24 #define REG_CTRL_GCAMEN                 0x00040
  25 #define REG_CTRL_CLHR__MASK             0x00300
  26 #define REG_CTRL_BITO__MASK             0x03000
  27 #define REG_CTRL_BITO_OFF               0x00000
  28 #define REG_CTRL_BITO_40PCC             0x01000
  29 #define REG_CTRL_BITO_80PCC             0x02000
  30 #define REG_CTRL_BITO_160PCC            0x03000
  31 #define REG_CTRL_GIBITO                 0x08000
  32 #define REG_CTRL_CLTO__MASK             0x70000
  33 #define REG_CTRL_CLTO_OFF               0x00000
  34
  35 #define REG_CMD                 0x04
  36 #define REG_CMD_START                   0x00001
  37 #define REG_CMD_STOP                    0x00002
  38 #define REG_CMD_ACK                     0x00004
  39 #define REG_CMD_NACK                    0x00008
  40 #define REG_CMD_CONT                    0x00010
  41 #define REG_CMD_ABORT                   0x00020
  42 #define REG_CMD_CLEARTX                 0x00040
  43 #define REG_CMD_CLEARPC                 0x00080
  44
  45 #define REG_STATE               0x08
  46 #define REG_STATE_BUSY                  0x00001
  47 #define REG_STATE_MASTER                0x00002
  48 #define REG_STATE_TRANSMITTER           0x00004
  49 #define REG_STATE_NACKED                0x00008
  50 #define REG_STATE_BUSHOLD               0x00010
  51 #define REG_STATE_STATE__MASK           0x000e0
  52 #define REG_STATE_STATE_IDLE            0x00000
  53 #define REG_STATE_STATE_WAIT            0x00020
  54 #define REG_STATE_STATE_START           0x00040
  55 #define REG_STATE_STATE_ADDR            0x00060
  56 #define REG_STATE_STATE_ADDRACK         0x00080
  57 #define REG_STATE_STATE_DATA            0x000a0
  58 #define REG_STATE_STATE_DATAACK         0x000c0
  59
  60 #define REG_STATUS              0x0c
  61 #define REG_STATUS_PSTART               0x00001
  62 #define REG_STATUS_PSTOP                0x00002
  63 #define REG_STATUS_PACK                 0x00004
  64 #define REG_STATUS_PNACK                0x00008
  65 #define REG_STATUS_PCONT                0x00010
  66 #define REG_STATUS_PABORT               0x00020
  67 #define REG_STATUS_TXC                  0x00040
  68 #define REG_STATUS_TXBL                 0x00080
  69 #define REG_STATUS_RXDATAV              0x00100
  70
  71 #define REG_CLKDIV              0x10
  72 #define REG_CLKDIV_DIV__MASK            0x001ff
  73 #define REG_CLKDIV_DIV(div)             MASK_VAL(REG_CLKDIV_DIV__MASK, (div))
  74
  75 #define REG_SADDR               0x14
  76 #define REG_SADDRMASK           0x18
  77 #define REG_RXDATA              0x1c
  78 #define REG_RXDATAP             0x20
  79 #define REG_TXDATA              0x24
  80 #define REG_IF                  0x28
  81 #define REG_IF_START                    0x00001
  82 #define REG_IF_RSTART                   0x00002
  83 #define REG_IF_ADDR                     0x00004
  84 #define REG_IF_TXC                      0x00008
  85 #define REG_IF_TXBL                     0x00010
  86 #define REG_IF_RXDATAV                  0x00020
  87 #define REG_IF_ACK                      0x00040
  88 #define REG_IF_NACK                     0x00080
  89 #define REG_IF_MSTOP                    0x00100
  90 #define REG_IF_ARBLOST                  0x00200
  91 #define REG_IF_BUSERR                   0x00400
  92 #define REG_IF_BUSHOLD                  0x00800
  93 #define REG_IF_TXOF                     0x01000
  94 #define REG_IF_RXUF                     0x02000
  95 #define REG_IF_BITO                     0x04000
  96 #define REG_IF_CLTO                     0x08000
  97 #define REG_IF_SSTOP                    0x10000
  98
  99 #define REG_IFS                 0x2c
 100 #define REG_IFC                 0x30
 101 #define REG_IFC__MASK                   0x1ffcf
 102
 103 #define REG_IEN                 0x34
 104
 105 #define REG_ROUTE               0x38
 106 #define REG_ROUTE_SDAPEN                0x00001
 107 #define REG_ROUTE_SCLPEN                0x00002
 108 #define REG_ROUTE_LOCATION__MASK        0x00700
 109 #define REG_ROUTE_LOCATION(n)           MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))
 110
 111 struct efm32_i2c_ddata {
 112         struct i2c_adapter adapter;
 113
 114         struct clk *clk;
 115         void __iomem *base;
 116         unsigned int irq;
 117         u8 location;
 118         unsigned long frequency;
 119
 120         /* transfer data */
 121         struct completion done;
 122         struct i2c_msg *msgs;
 123         size_t num_msgs;
 124         size_t current_word, current_msg;
 125         int retval;
 126 };
 127
 128 static u32 efm32_i2c_read32(struct efm32_i2c_ddata *ddata, unsigned offset)
 129 {
 130         return readl(ddata->base + offset);
 131 }
 132
 133 static void efm32_i2c_write32(struct efm32_i2c_ddata *ddata,
 134                 unsigned offset, u32 value)
 135 {
 136         writel(value, ddata->base + offset);
 137 }
 138
 139 static void efm32_i2c_send_next_msg(struct efm32_i2c_ddata *ddata)
 140 {
 141         struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
 142
 143         efm32_i2c_write32(ddata, REG_CMD, REG_CMD_START);
 144         efm32_i2c_write32(ddata, REG_TXDATA, i2c_8bit_addr_from_msg(cur_msg));
 145 }
 146
 147 static void efm32_i2c_send_next_byte(struct efm32_i2c_ddata *ddata)
 148 {
 149         struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
 150
 151         if (ddata->current_word >= cur_msg->len) {
 152                 /* cur_msg completely transferred */
 153                 ddata->current_word = 0;
 154                 ddata->current_msg += 1;
 155
 156                 if (ddata->current_msg >= ddata->num_msgs) {
 157                         efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
 158                         complete(&ddata->done);
 159                 } else {
 160                         efm32_i2c_send_next_msg(ddata);
 161                 }
 162         } else {
 163                 efm32_i2c_write32(ddata, REG_TXDATA,
 164                                 cur_msg->buf[ddata->current_word++]);
 165         }
 166 }
 167
 168 static void efm32_i2c_recv_next_byte(struct efm32_i2c_ddata *ddata)
 169 {
 170         struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
 171
 172         cur_msg->buf[ddata->current_word] = efm32_i2c_read32(ddata, REG_RXDATA);
 173         ddata->current_word += 1;
 174         if (ddata->current_word >= cur_msg->len) {
 175                 /* cur_msg completely transferred */
 176                 ddata->current_word = 0;
 177                 ddata->current_msg += 1;
 178
 179                 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_NACK);
 180
 181                 if (ddata->current_msg >= ddata->num_msgs) {
 182                         efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
 183                         complete(&ddata->done);
 184                 } else {
 185                         efm32_i2c_send_next_msg(ddata);
 186                 }
 187         } else {
 188                 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ACK);
 189         }
 190 }
 191
 192 static irqreturn_t efm32_i2c_irq(int irq, void *dev_id)
 193 {
 194         struct efm32_i2c_ddata *ddata = dev_id;
 195         struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
 196         u32 irqflag = efm32_i2c_read32(ddata, REG_IF);
 197         u32 state = efm32_i2c_read32(ddata, REG_STATE);
 198
 199         efm32_i2c_write32(ddata, REG_IFC, irqflag & REG_IFC__MASK);
 200
 201         switch (state & REG_STATE_STATE__MASK) {
 202         case REG_STATE_STATE_IDLE:
 203                 /* arbitration lost? */
 204                 ddata->retval = -EAGAIN;
 205                 complete(&ddata->done);
 206                 break;
 207         case REG_STATE_STATE_WAIT:
 208                 /*
 209                  * huh, this shouldn't happen.
 210                  * Reset hardware state and get out
 211                  */
 212                 ddata->retval = -EIO;
 213                 efm32_i2c_write32(ddata, REG_CMD,
 214                                 REG_CMD_STOP | REG_CMD_ABORT |
 215                                 REG_CMD_CLEARTX | REG_CMD_CLEARPC);
 216                 complete(&ddata->done);
 217                 break;
 218         case REG_STATE_STATE_START:
 219                 /* "caller" is expected to send an address */
 220                 break;
 221         case REG_STATE_STATE_ADDR:
 222                 /* wait for Ack or NAck of slave */
 223                 break;
 224         case REG_STATE_STATE_ADDRACK:
 225                 if (state & REG_STATE_NACKED) {
 226                         efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
 227                         ddata->retval = -ENXIO;
 228                         complete(&ddata->done);
 229                 } else if (cur_msg->flags & I2C_M_RD) {
 230                         /* wait for slave to send first data byte */
 231                 } else {
 232                         efm32_i2c_send_next_byte(ddata);
 233                 }
 234                 break;
 235         case REG_STATE_STATE_DATA:
 236                 if (cur_msg->flags & I2C_M_RD) {
 237                         efm32_i2c_recv_next_byte(ddata);
 238                 } else {
 239                         /* wait for Ack or Nack of slave */
 240                 }
 241                 break;
 242         case REG_STATE_STATE_DATAACK:
 243                 if (state & REG_STATE_NACKED) {
 244                         efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
 245                         complete(&ddata->done);
 246                 } else {
 247                         efm32_i2c_send_next_byte(ddata);
 248                 }
 249         }
 250
 251         return IRQ_HANDLED;
 252 }
 253
 254 static int efm32_i2c_master_xfer(struct i2c_adapter *adap,
 255                 struct i2c_msg *msgs, int num)
 256 {
 257         struct efm32_i2c_ddata *ddata = i2c_get_adapdata(adap);
 258         int ret;
 259
 260         if (ddata->msgs)
 261                 return -EBUSY;
 262
 263         ddata->msgs = msgs;
 264         ddata->num_msgs = num;
 265         ddata->current_word = 0;
 266         ddata->current_msg = 0;
 267         ddata->retval = -EIO;
 268
 269         reinit_completion(&ddata->done);
 270
 271         dev_dbg(&ddata->adapter.dev, "state: %08x, status: %08x\n",
 272                         efm32_i2c_read32(ddata, REG_STATE),
 273                         efm32_i2c_read32(ddata, REG_STATUS));
 274
 275         efm32_i2c_send_next_msg(ddata);
 276
 277         wait_for_completion(&ddata->done);
 278
 279         if (ddata->current_msg >= ddata->num_msgs)
 280                 ret = ddata->num_msgs;
 281         else
 282                 ret = ddata->retval;
 283
 284         return ret;
 285 }
 286
 287 static u32 efm32_i2c_functionality(struct i2c_adapter *adap)
 288 {
 289         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 290 }
 291
 292 static const struct i2c_algorithm efm32_i2c_algo = {
 293         .master_xfer = efm32_i2c_master_xfer,
 294         .functionality = efm32_i2c_functionality,
 295 };
 296
 297 static u32 efm32_i2c_get_configured_location(struct efm32_i2c_ddata *ddata)
 298 {
 299         u32 reg = efm32_i2c_read32(ddata, REG_ROUTE);
 300
 301         return (reg & REG_ROUTE_LOCATION__MASK) >>
 302                 __ffs(REG_ROUTE_LOCATION__MASK);
 303 }
 304
 305 static int efm32_i2c_probe(struct platform_device *pdev)
 306 {
 307         struct efm32_i2c_ddata *ddata;
 308         struct resource *res;
 309         unsigned long rate;
 310         struct device_node *np = pdev->dev.of_node;
 311         u32 location, frequency;
 312         int ret;
 313         u32 clkdiv;
 314
 315         if (!np)
 316                 return -EINVAL;
 317
 318         ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
 319         if (!ddata)
 320                 return -ENOMEM;
 321         platform_set_drvdata(pdev, ddata);
 322
 323         init_completion(&ddata->done);
 324         strlcpy(ddata->adapter.name, pdev->name, sizeof(ddata->adapter.name));
 325         ddata->adapter.owner = THIS_MODULE;
 326         ddata->adapter.algo = &efm32_i2c_algo;
 327         ddata->adapter.dev.parent = &pdev->dev;
 328         ddata->adapter.dev.of_node = pdev->dev.of_node;
 329         i2c_set_adapdata(&ddata->adapter, ddata);
 330
 331         ddata->clk = devm_clk_get(&pdev->dev, NULL);
 332         if (IS_ERR(ddata->clk)) {
 333                 ret = PTR_ERR(ddata->clk);
 334                 dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
 335                 return ret;
 336         }
 337
 338         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 339         if (!res) {
 340                 dev_err(&pdev->dev, "failed to determine base address\n");
 341                 return -ENODEV;
 342         }
 343
 344         if (resource_size(res) < 0x42) {
 345                 dev_err(&pdev->dev, "memory resource too small\n");
 346                 return -EINVAL;
 347         }
 348
 349         ddata->base = devm_ioremap_resource(&pdev->dev, res);
 350         if (IS_ERR(ddata->base))
 351                 return PTR_ERR(ddata->base);
 352
 353         ret = platform_get_irq(pdev, 0);
 354         if (ret <= 0) {
 355                 dev_err(&pdev->dev, "failed to get irq (%d)\n", ret);
 356                 if (!ret)
 357                         ret = -EINVAL;
 358                 return ret;
 359         }
 360
 361         ddata->irq = ret;
 362
 363         ret = clk_prepare_enable(ddata->clk);
 364         if (ret < 0) {
 365                 dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
 366                 return ret;
 367         }
 368
 369
 370         ret = of_property_read_u32(np, "energymicro,location", &location);
 371
 372         if (ret)
 373                 /* fall back to wrongly namespaced property */
 374                 ret = of_property_read_u32(np, "efm32,location", &location);
 375
 376         if (!ret) {
 377                 dev_dbg(&pdev->dev, "using location %u\n", location);
 378         } else {
 379                 /* default to location configured in hardware */
 380                 location = efm32_i2c_get_configured_location(ddata);
 381
 382                 dev_info(&pdev->dev, "fall back to location %u\n", location);
 383         }
 384
 385         ddata->location = location;
 386
 387         ret = of_property_read_u32(np, "clock-frequency", &frequency);
 388         if (!ret) {
 389                 dev_dbg(&pdev->dev, "using frequency %u\n", frequency);
 390         } else {
 391                 frequency = 100000;
 392                 dev_info(&pdev->dev, "defaulting to 100 kHz\n");
 393         }
 394         ddata->frequency = frequency;
 395
 396         rate = clk_get_rate(ddata->clk);
 397         if (!rate) {
 398                 dev_err(&pdev->dev, "there is no input clock available\n");
 399                 ret = -EINVAL;
 400                 goto err_disable_clk;
 401         }
 402         clkdiv = DIV_ROUND_UP(rate, 8 * ddata->frequency) - 1;
 403         if (clkdiv >= 0x200) {
 404                 dev_err(&pdev->dev,
 405                                 "input clock too fast (%lu) to divide down to bus freq (%lu)",
 406                                 rate, ddata->frequency);
 407                 ret = -EINVAL;
 408                 goto err_disable_clk;
 409         }
 410
 411         dev_dbg(&pdev->dev, "input clock = %lu, bus freq = %lu, clkdiv = %lu\n",
 412                         rate, ddata->frequency, (unsigned long)clkdiv);
 413         efm32_i2c_write32(ddata, REG_CLKDIV, REG_CLKDIV_DIV(clkdiv));
 414
 415         efm32_i2c_write32(ddata, REG_ROUTE, REG_ROUTE_SDAPEN |
 416                         REG_ROUTE_SCLPEN |
 417                         REG_ROUTE_LOCATION(ddata->location));
 418
 419         efm32_i2c_write32(ddata, REG_CTRL, REG_CTRL_EN |
 420                         REG_CTRL_BITO_160PCC | 0 * REG_CTRL_GIBITO);
 421
 422         efm32_i2c_write32(ddata, REG_IFC, REG_IFC__MASK);
 423         efm32_i2c_write32(ddata, REG_IEN, REG_IF_TXC | REG_IF_ACK | REG_IF_NACK
 424                         | REG_IF_ARBLOST | REG_IF_BUSERR | REG_IF_RXDATAV);
 425
 426         /* to make bus idle */
 427         efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ABORT);
 428
 429         ret = request_irq(ddata->irq, efm32_i2c_irq, 0, DRIVER_NAME, ddata);
 430         if (ret < 0) {
 431                 dev_err(&pdev->dev, "failed to request irq (%d)\n", ret);
 432                 goto err_disable_clk;
 433         }
 434
 435         ret = i2c_add_adapter(&ddata->adapter);
 436         if (ret) {
 437                 free_irq(ddata->irq, ddata);
 438
 439 err_disable_clk:
 440                 clk_disable_unprepare(ddata->clk);
 441         }
 442         return ret;
 443 }
 444
 445 static int efm32_i2c_remove(struct platform_device *pdev)
 446 {
 447         struct efm32_i2c_ddata *ddata = platform_get_drvdata(pdev);
 448
 449         i2c_del_adapter(&ddata->adapter);
 450         free_irq(ddata->irq, ddata);
 451         clk_disable_unprepare(ddata->clk);
 452
 453         return 0;
 454 }
 455
 456 static const struct of_device_id efm32_i2c_dt_ids[] = {
 457         {
 458                 .compatible = "energymicro,efm32-i2c",
 459         }, {
 460                 /* sentinel */
 461         }
 462 };
 463 MODULE_DEVICE_TABLE(of, efm32_i2c_dt_ids);
 464
 465 static struct platform_driver efm32_i2c_driver = {
 466         .probe = efm32_i2c_probe,
 467         .remove = efm32_i2c_remove,
 468
 469         .driver = {
 470                 .name = DRIVER_NAME,
 471                 .of_match_table = efm32_i2c_dt_ids,
 472         },
 473 };
 474 module_platform_driver(efm32_i2c_driver);
 475
 476 MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
 477 MODULE_DESCRIPTION("EFM32 i2c driver");
 478 MODULE_LICENSE("GPL v2");
 479 MODULE_ALIAS("platform:" DRIVER_NAME);