drivers/i2c/busses/i2c-wmt.c

   1 /*
   2  *  Wondermedia I2C Master Mode Driver
   3  *
   4  *  Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
   5  *
   6  *  Derived from GPLv2+ licensed source:
   7  *  - Copyright (C) 2008 WonderMedia Technologies, Inc.
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2, or
  11  *  (at your option) any later version. as published by the Free Software
  12  *  Foundation
  13  */
  14
  15 #include <linux/clk.h>
  16 #include <linux/delay.h>
  17 #include <linux/err.h>
  18 #include <linux/i2c.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/io.h>
  21 #include <linux/module.h>
  22 #include <linux/of.h>
  23 #include <linux/of_address.h>
  24 #include <linux/of_irq.h>
  25 #include <linux/platform_device.h>
  26
  27 #define REG_CR          0x00
  28 #define REG_TCR         0x02
  29 #define REG_CSR         0x04
  30 #define REG_ISR         0x06
  31 #define REG_IMR         0x08
  32 #define REG_CDR         0x0A
  33 #define REG_TR          0x0C
  34 #define REG_MCR         0x0E
  35 #define REG_SLAVE_CR    0x10
  36 #define REG_SLAVE_SR    0x12
  37 #define REG_SLAVE_ISR   0x14
  38 #define REG_SLAVE_IMR   0x16
  39 #define REG_SLAVE_DR    0x18
  40 #define REG_SLAVE_TR    0x1A
  41
  42 /* REG_CR Bit fields */
  43 #define CR_TX_NEXT_ACK          0x0000
  44 #define CR_ENABLE               0x0001
  45 #define CR_TX_NEXT_NO_ACK       0x0002
  46 #define CR_TX_END               0x0004
  47 #define CR_CPU_RDY              0x0008
  48 #define SLAV_MODE_SEL           0x8000
  49
  50 /* REG_TCR Bit fields */
  51 #define TCR_STANDARD_MODE       0x0000
  52 #define TCR_MASTER_WRITE        0x0000
  53 #define TCR_HS_MODE             0x2000
  54 #define TCR_MASTER_READ         0x4000
  55 #define TCR_FAST_MODE           0x8000
  56 #define TCR_SLAVE_ADDR_MASK     0x007F
  57
  58 /* REG_ISR Bit fields */
  59 #define ISR_NACK_ADDR           0x0001
  60 #define ISR_BYTE_END            0x0002
  61 #define ISR_SCL_TIMEOUT         0x0004
  62 #define ISR_WRITE_ALL           0x0007
  63
  64 /* REG_IMR Bit fields */
  65 #define IMR_ENABLE_ALL          0x0007
  66
  67 /* REG_CSR Bit fields */
  68 #define CSR_RCV_NOT_ACK         0x0001
  69 #define CSR_RCV_ACK_MASK        0x0001
  70 #define CSR_READY_MASK          0x0002
  71
  72 /* REG_TR */
  73 #define SCL_TIMEOUT(x)          (((x) & 0xFF) << 8)
  74 #define TR_STD                  0x0064
  75 #define TR_HS                   0x0019
  76
  77 /* REG_MCR */
  78 #define MCR_APB_96M             7
  79 #define MCR_APB_166M            12
  80
  81 #define I2C_MODE_STANDARD       0
  82 #define I2C_MODE_FAST           1
  83
  84 #define WMT_I2C_TIMEOUT         (msecs_to_jiffies(1000))
  85
  86 struct wmt_i2c_dev {
  87         struct i2c_adapter      adapter;
  88         struct completion       complete;
  89         struct device           *dev;
  90         void __iomem            *base;
  91         struct clk              *clk;
  92         int                     mode;
  93         int                     irq;
  94         u16                     cmd_status;
  95 };
  96
  97 static int wmt_i2c_wait_bus_not_busy(struct wmt_i2c_dev *i2c_dev)
  98 {
  99         unsigned long timeout;
 100
 101         timeout = jiffies + WMT_I2C_TIMEOUT;
 102         while (!(readw(i2c_dev->base + REG_CSR) & CSR_READY_MASK)) {
 103                 if (time_after(jiffies, timeout)) {
 104                         dev_warn(i2c_dev->dev, "timeout waiting for bus ready\n");
 105                         return -EBUSY;
 106                 }
 107                 msleep(20);
 108         }
 109
 110         return 0;
 111 }
 112
 113 static int wmt_check_status(struct wmt_i2c_dev *i2c_dev)
 114 {
 115         int ret = 0;
 116
 117         if (i2c_dev->cmd_status & ISR_NACK_ADDR)
 118                 ret = -EIO;
 119
 120         if (i2c_dev->cmd_status & ISR_SCL_TIMEOUT)
 121                 ret = -ETIMEDOUT;
 122
 123         return ret;
 124 }
 125
 126 static int wmt_i2c_write(struct i2c_adapter *adap, struct i2c_msg *pmsg,
 127                          int last)
 128 {
 129         struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 130         u16 val, tcr_val;
 131         int ret, wait_result;
 132         int xfer_len = 0;
 133
 134         if (!(pmsg->flags & I2C_M_NOSTART)) {
 135                 ret = wmt_i2c_wait_bus_not_busy(i2c_dev);
 136                 if (ret < 0)
 137                         return ret;
 138         }
 139
 140         if (pmsg->len == 0) {
 141                 /*
 142                  * We still need to run through the while (..) once, so
 143                  * start at -1 and break out early from the loop
 144                  */
 145                 xfer_len = -1;
 146                 writew(0, i2c_dev->base + REG_CDR);
 147         } else {
 148                 writew(pmsg->buf[0] & 0xFF, i2c_dev->base + REG_CDR);
 149         }
 150
 151         if (!(pmsg->flags & I2C_M_NOSTART)) {
 152                 val = readw(i2c_dev->base + REG_CR);
 153                 val &= ~CR_TX_END;
 154                 writew(val, i2c_dev->base + REG_CR);
 155
 156                 val = readw(i2c_dev->base + REG_CR);
 157                 val |= CR_CPU_RDY;
 158                 writew(val, i2c_dev->base + REG_CR);
 159         }
 160
 161         reinit_completion(&i2c_dev->complete);
 162
 163         if (i2c_dev->mode == I2C_MODE_STANDARD)
 164                 tcr_val = TCR_STANDARD_MODE;
 165         else
 166                 tcr_val = TCR_FAST_MODE;
 167
 168         tcr_val |= (TCR_MASTER_WRITE | (pmsg->addr & TCR_SLAVE_ADDR_MASK));
 169
 170         writew(tcr_val, i2c_dev->base + REG_TCR);
 171
 172         if (pmsg->flags & I2C_M_NOSTART) {
 173                 val = readw(i2c_dev->base + REG_CR);
 174                 val |= CR_CPU_RDY;
 175                 writew(val, i2c_dev->base + REG_CR);
 176         }
 177
 178         while (xfer_len < pmsg->len) {
 179                 wait_result = wait_for_completion_timeout(&i2c_dev->complete,
 180                                                           500 * HZ / 1000);
 181
 182                 if (wait_result == 0)
 183                         return -ETIMEDOUT;
 184
 185                 ret = wmt_check_status(i2c_dev);
 186                 if (ret)
 187                         return ret;
 188
 189                 xfer_len++;
 190
 191                 val = readw(i2c_dev->base + REG_CSR);
 192                 if ((val & CSR_RCV_ACK_MASK) == CSR_RCV_NOT_ACK) {
 193                         dev_dbg(i2c_dev->dev, "write RCV NACK error\n");
 194                         return -EIO;
 195                 }
 196
 197                 if (pmsg->len == 0) {
 198                         val = CR_TX_END | CR_CPU_RDY | CR_ENABLE;
 199                         writew(val, i2c_dev->base + REG_CR);
 200                         break;
 201                 }
 202
 203                 if (xfer_len == pmsg->len) {
 204                         if (last != 1)
 205                                 writew(CR_ENABLE, i2c_dev->base + REG_CR);
 206                 } else {
 207                         writew(pmsg->buf[xfer_len] & 0xFF, i2c_dev->base +
 208                                                                 REG_CDR);
 209                         writew(CR_CPU_RDY | CR_ENABLE, i2c_dev->base + REG_CR);
 210                 }
 211         }
 212
 213         return 0;
 214 }
 215
 216 static int wmt_i2c_read(struct i2c_adapter *adap, struct i2c_msg *pmsg,
 217                         int last)
 218 {
 219         struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 220         u16 val, tcr_val;
 221         int ret, wait_result;
 222         u32 xfer_len = 0;
 223
 224         if (!(pmsg->flags & I2C_M_NOSTART)) {
 225                 ret = wmt_i2c_wait_bus_not_busy(i2c_dev);
 226                 if (ret < 0)
 227                         return ret;
 228         }
 229
 230         val = readw(i2c_dev->base + REG_CR);
 231         val &= ~CR_TX_END;
 232         writew(val, i2c_dev->base + REG_CR);
 233
 234         val = readw(i2c_dev->base + REG_CR);
 235         val &= ~CR_TX_NEXT_NO_ACK;
 236         writew(val, i2c_dev->base + REG_CR);
 237
 238         if (!(pmsg->flags & I2C_M_NOSTART)) {
 239                 val = readw(i2c_dev->base + REG_CR);
 240                 val |= CR_CPU_RDY;
 241                 writew(val, i2c_dev->base + REG_CR);
 242         }
 243
 244         if (pmsg->len == 1) {
 245                 val = readw(i2c_dev->base + REG_CR);
 246                 val |= CR_TX_NEXT_NO_ACK;
 247                 writew(val, i2c_dev->base + REG_CR);
 248         }
 249
 250         reinit_completion(&i2c_dev->complete);
 251
 252         if (i2c_dev->mode == I2C_MODE_STANDARD)
 253                 tcr_val = TCR_STANDARD_MODE;
 254         else
 255                 tcr_val = TCR_FAST_MODE;
 256
 257         tcr_val |= TCR_MASTER_READ | (pmsg->addr & TCR_SLAVE_ADDR_MASK);
 258
 259         writew(tcr_val, i2c_dev->base + REG_TCR);
 260
 261         if (pmsg->flags & I2C_M_NOSTART) {
 262                 val = readw(i2c_dev->base + REG_CR);
 263                 val |= CR_CPU_RDY;
 264                 writew(val, i2c_dev->base + REG_CR);
 265         }
 266
 267         while (xfer_len < pmsg->len) {
 268                 wait_result = wait_for_completion_timeout(&i2c_dev->complete,
 269                                                           500 * HZ / 1000);
 270
 271                 if (!wait_result)
 272                         return -ETIMEDOUT;
 273
 274                 ret = wmt_check_status(i2c_dev);
 275                 if (ret)
 276                         return ret;
 277
 278                 pmsg->buf[xfer_len] = readw(i2c_dev->base + REG_CDR) >> 8;
 279                 xfer_len++;
 280
 281                 if (xfer_len == pmsg->len - 1) {
 282                         val = readw(i2c_dev->base + REG_CR);
 283                         val |= (CR_TX_NEXT_NO_ACK | CR_CPU_RDY);
 284                         writew(val, i2c_dev->base + REG_CR);
 285                 } else {
 286                         val = readw(i2c_dev->base + REG_CR);
 287                         val |= CR_CPU_RDY;
 288                         writew(val, i2c_dev->base + REG_CR);
 289                 }
 290         }
 291
 292         return 0;
 293 }
 294
 295 static int wmt_i2c_xfer(struct i2c_adapter *adap,
 296                         struct i2c_msg msgs[],
 297                         int num)
 298 {
 299         struct i2c_msg *pmsg;
 300         int i, is_last;
 301         int ret = 0;
 302
 303         for (i = 0; ret >= 0 && i < num; i++) {
 304                 is_last = ((i + 1) == num);
 305
 306                 pmsg = &msgs[i];
 307                 if (pmsg->flags & I2C_M_RD)
 308                         ret = wmt_i2c_read(adap, pmsg, is_last);
 309                 else
 310                         ret = wmt_i2c_write(adap, pmsg, is_last);
 311         }
 312
 313         return (ret < 0) ? ret : i;
 314 }
 315
 316 static u32 wmt_i2c_func(struct i2c_adapter *adap)
 317 {
 318         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
 319 }
 320
 321 static const struct i2c_algorithm wmt_i2c_algo = {
 322         .master_xfer    = wmt_i2c_xfer,
 323         .functionality  = wmt_i2c_func,
 324 };
 325
 326 static irqreturn_t wmt_i2c_isr(int irq, void *data)
 327 {
 328         struct wmt_i2c_dev *i2c_dev = data;
 329
 330         /* save the status and write-clear it */
 331         i2c_dev->cmd_status = readw(i2c_dev->base + REG_ISR);
 332         writew(i2c_dev->cmd_status, i2c_dev->base + REG_ISR);
 333
 334         complete(&i2c_dev->complete);
 335
 336         return IRQ_HANDLED;
 337 }
 338
 339 static int wmt_i2c_reset_hardware(struct wmt_i2c_dev *i2c_dev)
 340 {
 341         int err;
 342
 343         err = clk_prepare_enable(i2c_dev->clk);
 344         if (err) {
 345                 dev_err(i2c_dev->dev, "failed to enable clock\n");
 346                 return err;
 347         }
 348
 349         err = clk_set_rate(i2c_dev->clk, 20000000);
 350         if (err) {
 351                 dev_err(i2c_dev->dev, "failed to set clock = 20Mhz\n");
 352                 return err;
 353         }
 354
 355         writew(0, i2c_dev->base + REG_CR);
 356         writew(MCR_APB_166M, i2c_dev->base + REG_MCR);
 357         writew(ISR_WRITE_ALL, i2c_dev->base + REG_ISR);
 358         writew(IMR_ENABLE_ALL, i2c_dev->base + REG_IMR);
 359         writew(CR_ENABLE, i2c_dev->base + REG_CR);
 360         readw(i2c_dev->base + REG_CSR);         /* read clear */
 361         writew(ISR_WRITE_ALL, i2c_dev->base + REG_ISR);
 362
 363         if (i2c_dev->mode == I2C_MODE_STANDARD)
 364                 writew(SCL_TIMEOUT(128) | TR_STD, i2c_dev->base + REG_TR);
 365         else
 366                 writew(SCL_TIMEOUT(128) | TR_HS, i2c_dev->base + REG_TR);
 367
 368         return 0;
 369 }
 370
 371 static int wmt_i2c_probe(struct platform_device *pdev)
 372 {
 373         struct device_node *np = pdev->dev.of_node;
 374         struct wmt_i2c_dev *i2c_dev;
 375         struct i2c_adapter *adap;
 376         struct resource *res;
 377         int err;
 378         u32 clk_rate;
 379
 380         i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
 381         if (!i2c_dev) {
 382                 dev_err(&pdev->dev, "device memory allocation failed\n");
 383                 return -ENOMEM;
 384         }
 385
 386         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 387         i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
 388         if (IS_ERR(i2c_dev->base))
 389                 return PTR_ERR(i2c_dev->base);
 390
 391         i2c_dev->irq = irq_of_parse_and_map(np, 0);
 392         if (!i2c_dev->irq) {
 393                 dev_err(&pdev->dev, "irq missing or invalid\n");
 394                 return -EINVAL;
 395         }
 396
 397         i2c_dev->clk = of_clk_get(np, 0);
 398         if (IS_ERR(i2c_dev->clk)) {
 399                 dev_err(&pdev->dev, "unable to request clock\n");
 400                 return PTR_ERR(i2c_dev->clk);
 401         }
 402
 403         i2c_dev->mode = I2C_MODE_STANDARD;
 404         err = of_property_read_u32(np, "clock-frequency", &clk_rate);
 405         if ((!err) && (clk_rate == 400000))
 406                 i2c_dev->mode = I2C_MODE_FAST;
 407
 408         i2c_dev->dev = &pdev->dev;
 409
 410         err = devm_request_irq(&pdev->dev, i2c_dev->irq, wmt_i2c_isr, 0,
 411                                                         "i2c", i2c_dev);
 412         if (err) {
 413                 dev_err(&pdev->dev, "failed to request irq %i\n", i2c_dev->irq);
 414                 return err;
 415         }
 416
 417         adap = &i2c_dev->adapter;
 418         i2c_set_adapdata(adap, i2c_dev);
 419         strlcpy(adap->name, "WMT I2C adapter", sizeof(adap->name));
 420         adap->owner = THIS_MODULE;
 421         adap->algo = &wmt_i2c_algo;
 422         adap->dev.parent = &pdev->dev;
 423         adap->dev.of_node = pdev->dev.of_node;
 424
 425         init_completion(&i2c_dev->complete);
 426
 427         err = wmt_i2c_reset_hardware(i2c_dev);
 428         if (err) {
 429                 dev_err(&pdev->dev, "error initializing hardware\n");
 430                 return err;
 431         }
 432
 433         err = i2c_add_adapter(adap);
 434         if (err) {
 435                 dev_err(&pdev->dev, "failed to add adapter\n");
 436                 return err;
 437         }
 438
 439         platform_set_drvdata(pdev, i2c_dev);
 440
 441         return 0;
 442 }
 443
 444 static int wmt_i2c_remove(struct platform_device *pdev)
 445 {
 446         struct wmt_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
 447
 448         /* Disable interrupts, clock and delete adapter */
 449         writew(0, i2c_dev->base + REG_IMR);
 450         clk_disable_unprepare(i2c_dev->clk);
 451         i2c_del_adapter(&i2c_dev->adapter);
 452
 453         return 0;
 454 }
 455
 456 static struct of_device_id wmt_i2c_dt_ids[] = {
 457         { .compatible = "wm,wm8505-i2c" },
 458         { /* Sentinel */ },
 459 };
 460
 461 static struct platform_driver wmt_i2c_driver = {
 462         .probe          = wmt_i2c_probe,
 463         .remove         = wmt_i2c_remove,
 464         .driver         = {
 465                 .name   = "wmt-i2c",
 466                 .owner  = THIS_MODULE,
 467                 .of_match_table = wmt_i2c_dt_ids,
 468         },
 469 };
 470
 471 module_platform_driver(wmt_i2c_driver);
 472
 473 MODULE_DESCRIPTION("Wondermedia I2C master-mode bus adapter");
 474 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
 475 MODULE_LICENSE("GPL");
 476 MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids);