drivers/i2c/busses/i2c-mxs.c

   1 /*
   2  * Freescale MXS I2C bus driver
   3  *
   4  * Copyright (C) 2012-2013 Marek Vasut <marex@denx.de>
   5  * Copyright (C) 2011-2012 Wolfram Sang, Pengutronix e.K.
   6  *
   7  * based on a (non-working) driver which was:
   8  *
   9  * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  */
  17
  18 #include <linux/slab.h>
  19 #include <linux/device.h>
  20 #include <linux/module.h>
  21 #include <linux/i2c.h>
  22 #include <linux/err.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/completion.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/jiffies.h>
  27 #include <linux/io.h>
  28 #include <linux/stmp_device.h>
  29 #include <linux/of.h>
  30 #include <linux/of_device.h>
  31 #include <linux/dma-mapping.h>
  32 #include <linux/dmaengine.h>
  33
  34 #define DRIVER_NAME "mxs-i2c"
  35
  36 #define MXS_I2C_CTRL0           (0x00)
  37 #define MXS_I2C_CTRL0_SET       (0x04)
  38 #define MXS_I2C_CTRL0_CLR       (0x08)
  39
  40 #define MXS_I2C_CTRL0_SFTRST                    0x80000000
  41 #define MXS_I2C_CTRL0_RUN                       0x20000000
  42 #define MXS_I2C_CTRL0_SEND_NAK_ON_LAST          0x02000000
  43 #define MXS_I2C_CTRL0_PIO_MODE                  0x01000000
  44 #define MXS_I2C_CTRL0_RETAIN_CLOCK              0x00200000
  45 #define MXS_I2C_CTRL0_POST_SEND_STOP            0x00100000
  46 #define MXS_I2C_CTRL0_PRE_SEND_START            0x00080000
  47 #define MXS_I2C_CTRL0_MASTER_MODE               0x00020000
  48 #define MXS_I2C_CTRL0_DIRECTION                 0x00010000
  49 #define MXS_I2C_CTRL0_XFER_COUNT(v)             ((v) & 0x0000FFFF)
  50
  51 #define MXS_I2C_TIMING0         (0x10)
  52 #define MXS_I2C_TIMING1         (0x20)
  53 #define MXS_I2C_TIMING2         (0x30)
  54
  55 #define MXS_I2C_CTRL1           (0x40)
  56 #define MXS_I2C_CTRL1_SET       (0x44)
  57 #define MXS_I2C_CTRL1_CLR       (0x48)
  58
  59 #define MXS_I2C_CTRL1_CLR_GOT_A_NAK             0x10000000
  60 #define MXS_I2C_CTRL1_BUS_FREE_IRQ              0x80
  61 #define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ     0x40
  62 #define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ          0x20
  63 #define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ    0x10
  64 #define MXS_I2C_CTRL1_EARLY_TERM_IRQ            0x08
  65 #define MXS_I2C_CTRL1_MASTER_LOSS_IRQ           0x04
  66 #define MXS_I2C_CTRL1_SLAVE_STOP_IRQ            0x02
  67 #define MXS_I2C_CTRL1_SLAVE_IRQ                 0x01
  68
  69 #define MXS_I2C_STAT            (0x50)
  70 #define MXS_I2C_STAT_GOT_A_NAK                  0x10000000
  71 #define MXS_I2C_STAT_BUS_BUSY                   0x00000800
  72 #define MXS_I2C_STAT_CLK_GEN_BUSY               0x00000400
  73
  74 #define MXS_I2C_DATA(i2c)       ((i2c->dev_type == MXS_I2C_V1) ? 0x60 : 0xa0)
  75
  76 #define MXS_I2C_DEBUG0_CLR(i2c) ((i2c->dev_type == MXS_I2C_V1) ? 0x78 : 0xb8)
  77
  78 #define MXS_I2C_DEBUG0_DMAREQ   0x80000000
  79
  80 #define MXS_I2C_IRQ_MASK        (MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
  81                                  MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
  82                                  MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
  83                                  MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
  84                                  MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
  85                                  MXS_I2C_CTRL1_SLAVE_IRQ)
  86
  87
  88 #define MXS_CMD_I2C_SELECT      (MXS_I2C_CTRL0_RETAIN_CLOCK |   \
  89                                  MXS_I2C_CTRL0_PRE_SEND_START | \
  90                                  MXS_I2C_CTRL0_MASTER_MODE |    \
  91                                  MXS_I2C_CTRL0_DIRECTION |      \
  92                                  MXS_I2C_CTRL0_XFER_COUNT(1))
  93
  94 #define MXS_CMD_I2C_WRITE       (MXS_I2C_CTRL0_PRE_SEND_START | \
  95                                  MXS_I2C_CTRL0_MASTER_MODE |    \
  96                                  MXS_I2C_CTRL0_DIRECTION)
  97
  98 #define MXS_CMD_I2C_READ        (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
  99                                  MXS_I2C_CTRL0_MASTER_MODE)
 100
 101 enum mxs_i2c_devtype {
 102         MXS_I2C_UNKNOWN = 0,
 103         MXS_I2C_V1,
 104         MXS_I2C_V2,
 105 };
 106
 107 /**
 108  * struct mxs_i2c_dev - per device, private MXS-I2C data
 109  *
 110  * @dev: driver model device node
 111  * @dev_type: distinguish i.MX23/i.MX28 features
 112  * @regs: IO registers pointer
 113  * @cmd_complete: completion object for transaction wait
 114  * @cmd_err: error code for last transaction
 115  * @adapter: i2c subsystem adapter node
 116  */
 117 struct mxs_i2c_dev {
 118         struct device *dev;
 119         enum mxs_i2c_devtype dev_type;
 120         void __iomem *regs;
 121         struct completion cmd_complete;
 122         int cmd_err;
 123         struct i2c_adapter adapter;
 124
 125         uint32_t timing0;
 126         uint32_t timing1;
 127         uint32_t timing2;
 128
 129         /* DMA support components */
 130         struct dma_chan                 *dmach;
 131         uint32_t                        pio_data[2];
 132         uint32_t                        addr_data;
 133         struct scatterlist              sg_io[2];
 134         bool                            dma_read;
 135 };
 136
 137 static int mxs_i2c_reset(struct mxs_i2c_dev *i2c)
 138 {
 139         int ret = stmp_reset_block(i2c->regs);
 140         if (ret)
 141                 return ret;
 142
 143         /*
 144          * Configure timing for the I2C block. The I2C TIMING2 register has to
 145          * be programmed with this particular magic number. The rest is derived
 146          * from the XTAL speed and requested I2C speed.
 147          *
 148          * For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
 149          */
 150         writel(i2c->timing0, i2c->regs + MXS_I2C_TIMING0);
 151         writel(i2c->timing1, i2c->regs + MXS_I2C_TIMING1);
 152         writel(i2c->timing2, i2c->regs + MXS_I2C_TIMING2);
 153
 154         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
 155
 156         return 0;
 157 }
 158
 159 static void mxs_i2c_dma_finish(struct mxs_i2c_dev *i2c)
 160 {
 161         if (i2c->dma_read) {
 162                 dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 163                 dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 164         } else {
 165                 dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 166         }
 167 }
 168
 169 static void mxs_i2c_dma_irq_callback(void *param)
 170 {
 171         struct mxs_i2c_dev *i2c = param;
 172
 173         complete(&i2c->cmd_complete);
 174         mxs_i2c_dma_finish(i2c);
 175 }
 176
 177 static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
 178                         struct i2c_msg *msg, uint32_t flags)
 179 {
 180         struct dma_async_tx_descriptor *desc;
 181         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 182
 183         if (msg->flags & I2C_M_RD) {
 184                 i2c->dma_read = 1;
 185                 i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_READ;
 186
 187                 /*
 188                  * SELECT command.
 189                  */
 190
 191                 /* Queue the PIO register write transfer. */
 192                 i2c->pio_data[0] = MXS_CMD_I2C_SELECT;
 193                 desc = dmaengine_prep_slave_sg(i2c->dmach,
 194                                         (struct scatterlist *)&i2c->pio_data[0],
 195                                         1, DMA_TRANS_NONE, 0);
 196                 if (!desc) {
 197                         dev_err(i2c->dev,
 198                                 "Failed to get PIO reg. write descriptor.\n");
 199                         goto select_init_pio_fail;
 200                 }
 201
 202                 /* Queue the DMA data transfer. */
 203                 sg_init_one(&i2c->sg_io[0], &i2c->addr_data, 1);
 204                 dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 205                 desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
 206                                         DMA_MEM_TO_DEV,
 207                                         DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 208                 if (!desc) {
 209                         dev_err(i2c->dev,
 210                                 "Failed to get DMA data write descriptor.\n");
 211                         goto select_init_dma_fail;
 212                 }
 213
 214                 /*
 215                  * READ command.
 216                  */
 217
 218                 /* Queue the PIO register write transfer. */
 219                 i2c->pio_data[1] = flags | MXS_CMD_I2C_READ |
 220                                 MXS_I2C_CTRL0_XFER_COUNT(msg->len);
 221                 desc = dmaengine_prep_slave_sg(i2c->dmach,
 222                                         (struct scatterlist *)&i2c->pio_data[1],
 223                                         1, DMA_TRANS_NONE, DMA_PREP_INTERRUPT);
 224                 if (!desc) {
 225                         dev_err(i2c->dev,
 226                                 "Failed to get PIO reg. write descriptor.\n");
 227                         goto select_init_dma_fail;
 228                 }
 229
 230                 /* Queue the DMA data transfer. */
 231                 sg_init_one(&i2c->sg_io[1], msg->buf, msg->len);
 232                 dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 233                 desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
 234                                         DMA_DEV_TO_MEM,
 235                                         DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 236                 if (!desc) {
 237                         dev_err(i2c->dev,
 238                                 "Failed to get DMA data write descriptor.\n");
 239                         goto read_init_dma_fail;
 240                 }
 241         } else {
 242                 i2c->dma_read = 0;
 243                 i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_WRITE;
 244
 245                 /*
 246                  * WRITE command.
 247                  */
 248
 249                 /* Queue the PIO register write transfer. */
 250                 i2c->pio_data[0] = flags | MXS_CMD_I2C_WRITE |
 251                                 MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1);
 252                 desc = dmaengine_prep_slave_sg(i2c->dmach,
 253                                         (struct scatterlist *)&i2c->pio_data[0],
 254                                         1, DMA_TRANS_NONE, 0);
 255                 if (!desc) {
 256                         dev_err(i2c->dev,
 257                                 "Failed to get PIO reg. write descriptor.\n");
 258                         goto write_init_pio_fail;
 259                 }
 260
 261                 /* Queue the DMA data transfer. */
 262                 sg_init_table(i2c->sg_io, 2);
 263                 sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1);
 264                 sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len);
 265                 dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 266                 desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
 267                                         DMA_MEM_TO_DEV,
 268                                         DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 269                 if (!desc) {
 270                         dev_err(i2c->dev,
 271                                 "Failed to get DMA data write descriptor.\n");
 272                         goto write_init_dma_fail;
 273                 }
 274         }
 275
 276         /*
 277          * The last descriptor must have this callback,
 278          * to finish the DMA transaction.
 279          */
 280         desc->callback = mxs_i2c_dma_irq_callback;
 281         desc->callback_param = i2c;
 282
 283         /* Start the transfer. */
 284         dmaengine_submit(desc);
 285         dma_async_issue_pending(i2c->dmach);
 286         return 0;
 287
 288 /* Read failpath. */
 289 read_init_dma_fail:
 290         dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 291 select_init_dma_fail:
 292         dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 293 select_init_pio_fail:
 294         dmaengine_terminate_all(i2c->dmach);
 295         return -EINVAL;
 296
 297 /* Write failpath. */
 298 write_init_dma_fail:
 299         dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 300 write_init_pio_fail:
 301         dmaengine_terminate_all(i2c->dmach);
 302         return -EINVAL;
 303 }
 304
 305 static int mxs_i2c_pio_wait_xfer_end(struct mxs_i2c_dev *i2c)
 306 {
 307         unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 308
 309         while (readl(i2c->regs + MXS_I2C_CTRL0) & MXS_I2C_CTRL0_RUN) {
 310                 if (time_after(jiffies, timeout))
 311                         return -ETIMEDOUT;
 312                 cond_resched();
 313         }
 314
 315         return 0;
 316 }
 317
 318 static int mxs_i2c_pio_check_error_state(struct mxs_i2c_dev *i2c)
 319 {
 320         u32 state;
 321
 322         state = readl(i2c->regs + MXS_I2C_CTRL1_CLR) & MXS_I2C_IRQ_MASK;
 323
 324         if (state & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
 325                 i2c->cmd_err = -ENXIO;
 326         else if (state & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
 327                           MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
 328                           MXS_I2C_CTRL1_SLAVE_STOP_IRQ |
 329                           MXS_I2C_CTRL1_SLAVE_IRQ))
 330                 i2c->cmd_err = -EIO;
 331
 332         return i2c->cmd_err;
 333 }
 334
 335 static void mxs_i2c_pio_trigger_cmd(struct mxs_i2c_dev *i2c, u32 cmd)
 336 {
 337         u32 reg;
 338
 339         writel(cmd, i2c->regs + MXS_I2C_CTRL0);
 340
 341         /* readback makes sure the write is latched into hardware */
 342         reg = readl(i2c->regs + MXS_I2C_CTRL0);
 343         reg |= MXS_I2C_CTRL0_RUN;
 344         writel(reg, i2c->regs + MXS_I2C_CTRL0);
 345 }
 346
 347 /*
 348  * Start WRITE transaction on the I2C bus. By studying i.MX23 datasheet,
 349  * CTRL0::PIO_MODE bit description clarifies the order in which the registers
 350  * must be written during PIO mode operation. First, the CTRL0 register has
 351  * to be programmed with all the necessary bits but the RUN bit. Then the
 352  * payload has to be written into the DATA register. Finally, the transmission
 353  * is executed by setting the RUN bit in CTRL0.
 354  */
 355 static void mxs_i2c_pio_trigger_write_cmd(struct mxs_i2c_dev *i2c, u32 cmd,
 356                                           u32 data)
 357 {
 358         writel(cmd, i2c->regs + MXS_I2C_CTRL0);
 359
 360         if (i2c->dev_type == MXS_I2C_V1)
 361                 writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_SET);
 362
 363         writel(data, i2c->regs + MXS_I2C_DATA(i2c));
 364         writel(MXS_I2C_CTRL0_RUN, i2c->regs + MXS_I2C_CTRL0_SET);
 365 }
 366
 367 static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
 368                         struct i2c_msg *msg, uint32_t flags)
 369 {
 370         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 371         uint32_t addr_data = msg->addr << 1;
 372         uint32_t data = 0;
 373         int i, ret, xlen = 0, xmit = 0;
 374         uint32_t start;
 375
 376         /* Mute IRQs coming from this block. */
 377         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_CLR);
 378
 379         /*
 380          * MX23 idea:
 381          * - Enable CTRL0::PIO_MODE (1 << 24)
 382          * - Enable CTRL1::ACK_MODE (1 << 27)
 383          *
 384          * WARNING! The MX23 is broken in some way, even if it claims
 385          * to support PIO, when we try to transfer any amount of data
 386          * that is not aligned to 4 bytes, the DMA engine will have
 387          * bits in DEBUG1::DMA_BYTES_ENABLES still set even after the
 388          * transfer. This in turn will mess up the next transfer as
 389          * the block it emit one byte write onto the bus terminated
 390          * with a NAK+STOP. A possible workaround is to reset the IP
 391          * block after every PIO transmission, which might just work.
 392          *
 393          * NOTE: The CTRL0::PIO_MODE description is important, since
 394          * it outlines how the PIO mode is really supposed to work.
 395          */
 396         if (msg->flags & I2C_M_RD) {
 397                 /*
 398                  * PIO READ transfer:
 399                  *
 400                  * This transfer MUST be limited to 4 bytes maximum. It is not
 401                  * possible to transfer more than four bytes via PIO, since we
 402                  * can not in any way make sure we can read the data from the
 403                  * DATA register fast enough. Besides, the RX FIFO is only four
 404                  * bytes deep, thus we can only really read up to four bytes at
 405                  * time. Finally, there is no bit indicating us that new data
 406                  * arrived at the FIFO and can thus be fetched from the DATA
 407                  * register.
 408                  */
 409                 BUG_ON(msg->len > 4);
 410
 411                 addr_data |= I2C_SMBUS_READ;
 412
 413                 /* SELECT command. */
 414                 mxs_i2c_pio_trigger_write_cmd(i2c, MXS_CMD_I2C_SELECT,
 415                                               addr_data);
 416
 417                 ret = mxs_i2c_pio_wait_xfer_end(i2c);
 418                 if (ret) {
 419                         dev_err(i2c->dev,
 420                                 "PIO: Failed to send SELECT command!\n");
 421                         goto cleanup;
 422                 }
 423
 424                 /* READ command. */
 425                 mxs_i2c_pio_trigger_cmd(i2c,
 426                                         MXS_CMD_I2C_READ | flags |
 427                                         MXS_I2C_CTRL0_XFER_COUNT(msg->len));
 428
 429                 ret = mxs_i2c_pio_wait_xfer_end(i2c);
 430                 if (ret) {
 431                         dev_err(i2c->dev,
 432                                 "PIO: Failed to send SELECT command!\n");
 433                         goto cleanup;
 434                 }
 435
 436                 data = readl(i2c->regs + MXS_I2C_DATA(i2c));
 437                 for (i = 0; i < msg->len; i++) {
 438                         msg->buf[i] = data & 0xff;
 439                         data >>= 8;
 440                 }
 441         } else {
 442                 /*
 443                  * PIO WRITE transfer:
 444                  *
 445                  * The code below implements clock stretching to circumvent
 446                  * the possibility of kernel not being able to supply data
 447                  * fast enough. It is possible to transfer arbitrary amount
 448                  * of data using PIO write.
 449                  */
 450                 addr_data |= I2C_SMBUS_WRITE;
 451
 452                 /*
 453                  * The LSB of data buffer is the first byte blasted across
 454                  * the bus. Higher order bytes follow. Thus the following
 455                  * filling schematic.
 456                  */
 457
 458                 data = addr_data << 24;
 459
 460                 /* Start the transfer with START condition. */
 461                 start = MXS_I2C_CTRL0_PRE_SEND_START;
 462
 463                 /* If the transfer is long, use clock stretching. */
 464                 if (msg->len > 3)
 465                         start |= MXS_I2C_CTRL0_RETAIN_CLOCK;
 466
 467                 for (i = 0; i < msg->len; i++) {
 468                         data >>= 8;
 469                         data |= (msg->buf[i] << 24);
 470
 471                         xmit = 0;
 472
 473                         /* This is the last transfer of the message. */
 474                         if (i + 1 == msg->len) {
 475                                 /* Add optional STOP flag. */
 476                                 start |= flags;
 477                                 /* Remove RETAIN_CLOCK bit. */
 478                                 start &= ~MXS_I2C_CTRL0_RETAIN_CLOCK;
 479                                 xmit = 1;
 480                         }
 481
 482                         /* Four bytes are ready in the "data" variable. */
 483                         if ((i & 3) == 2)
 484                                 xmit = 1;
 485
 486                         /* Nothing interesting happened, continue stuffing. */
 487                         if (!xmit)
 488                                 continue;
 489
 490                         /*
 491                          * Compute the size of the transfer and shift the
 492                          * data accordingly.
 493                          *
 494                          * i = (4k + 0) .... xlen = 2
 495                          * i = (4k + 1) .... xlen = 3
 496                          * i = (4k + 2) .... xlen = 4
 497                          * i = (4k + 3) .... xlen = 1
 498                          */
 499
 500                         if ((i % 4) == 3)
 501                                 xlen = 1;
 502                         else
 503                                 xlen = (i % 4) + 2;
 504
 505                         data >>= (4 - xlen) * 8;
 506
 507                         dev_dbg(i2c->dev,
 508                                 "PIO: len=%i pos=%i total=%i [W%s%s%s]\n",
 509                                 xlen, i, msg->len,
 510                                 start & MXS_I2C_CTRL0_PRE_SEND_START ? "S" : "",
 511                                 start & MXS_I2C_CTRL0_POST_SEND_STOP ? "E" : "",
 512                                 start & MXS_I2C_CTRL0_RETAIN_CLOCK ? "C" : "");
 513
 514                         writel(MXS_I2C_DEBUG0_DMAREQ,
 515                                i2c->regs + MXS_I2C_DEBUG0_CLR(i2c));
 516
 517                         mxs_i2c_pio_trigger_write_cmd(i2c,
 518                                 start | MXS_I2C_CTRL0_MASTER_MODE |
 519                                 MXS_I2C_CTRL0_DIRECTION |
 520                                 MXS_I2C_CTRL0_XFER_COUNT(xlen), data);
 521
 522                         /* The START condition is sent only once. */
 523                         start &= ~MXS_I2C_CTRL0_PRE_SEND_START;
 524
 525                         /* Wait for the end of the transfer. */
 526                         ret = mxs_i2c_pio_wait_xfer_end(i2c);
 527                         if (ret) {
 528                                 dev_err(i2c->dev,
 529                                         "PIO: Failed to finish WRITE cmd!\n");
 530                                 break;
 531                         }
 532
 533                         /* Check NAK here. */
 534                         ret = readl(i2c->regs + MXS_I2C_STAT) &
 535                                     MXS_I2C_STAT_GOT_A_NAK;
 536                         if (ret) {
 537                                 ret = -ENXIO;
 538                                 goto cleanup;
 539                         }
 540                 }
 541         }
 542
 543         /* make sure we capture any occurred error into cmd_err */
 544         ret = mxs_i2c_pio_check_error_state(i2c);
 545
 546 cleanup:
 547         /* Clear any dangling IRQs and re-enable interrupts. */
 548         writel(MXS_I2C_IRQ_MASK, i2c->regs + MXS_I2C_CTRL1_CLR);
 549         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
 550
 551         /* Clear the PIO_MODE on i.MX23 */
 552         if (i2c->dev_type == MXS_I2C_V1)
 553                 writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_CLR);
 554
 555         return ret;
 556 }
 557
 558 /*
 559  * Low level master read/write transaction.
 560  */
 561 static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 562                                 int stop)
 563 {
 564         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 565         int ret;
 566         int flags;
 567         int use_pio = 0;
 568
 569         flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
 570
 571         dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
 572                 msg->addr, msg->len, msg->flags, stop);
 573
 574         if (msg->len == 0)
 575                 return -EINVAL;
 576
 577         /*
 578          * The MX28 I2C IP block can only do PIO READ for transfer of to up
 579          * 4 bytes of length. The write transfer is not limited as it can use
 580          * clock stretching to avoid FIFO underruns.
 581          */
 582         if ((msg->flags & I2C_M_RD) && (msg->len <= 4))
 583                 use_pio = 1;
 584         if (!(msg->flags & I2C_M_RD) && (msg->len < 7))
 585                 use_pio = 1;
 586
 587         i2c->cmd_err = 0;
 588         if (use_pio) {
 589                 ret = mxs_i2c_pio_setup_xfer(adap, msg, flags);
 590                 /* No need to reset the block if NAK was received. */
 591                 if (ret && (ret != -ENXIO))
 592                         mxs_i2c_reset(i2c);
 593         } else {
 594                 INIT_COMPLETION(i2c->cmd_complete);
 595                 ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
 596                 if (ret)
 597                         return ret;
 598
 599                 ret = wait_for_completion_timeout(&i2c->cmd_complete,
 600                                                 msecs_to_jiffies(1000));
 601                 if (ret == 0)
 602                         goto timeout;
 603
 604                 ret = i2c->cmd_err;
 605         }
 606
 607         if (ret == -ENXIO) {
 608                 /*
 609                  * If the transfer fails with a NAK from the slave the
 610                  * controller halts until it gets told to return to idle state.
 611                  */
 612                 writel(MXS_I2C_CTRL1_CLR_GOT_A_NAK,
 613                        i2c->regs + MXS_I2C_CTRL1_SET);
 614         }
 615
 616         /*
 617          * WARNING!
 618          * The i.MX23 is strange. After each and every operation, it's I2C IP
 619          * block must be reset, otherwise the IP block will misbehave. This can
 620          * be observed on the bus by the block sending out one single byte onto
 621          * the bus. In case such an error happens, bit 27 will be set in the
 622          * DEBUG0 register. This bit is not documented in the i.MX23 datasheet
 623          * and is marked as "TBD" instead. To reset this bit to a correct state,
 624          * reset the whole block. Since the block reset does not take long, do
 625          * reset the block after every transfer to play safe.
 626          */
 627         if (i2c->dev_type == MXS_I2C_V1)
 628                 mxs_i2c_reset(i2c);
 629
 630         dev_dbg(i2c->dev, "Done with err=%d\n", ret);
 631
 632         return ret;
 633
 634 timeout:
 635         dev_dbg(i2c->dev, "Timeout!\n");
 636         mxs_i2c_dma_finish(i2c);
 637         ret = mxs_i2c_reset(i2c);
 638         if (ret)
 639                 return ret;
 640
 641         return -ETIMEDOUT;
 642 }
 643
 644 static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 645                         int num)
 646 {
 647         int i;
 648         int err;
 649
 650         for (i = 0; i < num; i++) {
 651                 err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
 652                 if (err)
 653                         return err;
 654         }
 655
 656         return num;
 657 }
 658
 659 static u32 mxs_i2c_func(struct i2c_adapter *adap)
 660 {
 661         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 662 }
 663
 664 static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
 665 {
 666         struct mxs_i2c_dev *i2c = dev_id;
 667         u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
 668
 669         if (!stat)
 670                 return IRQ_NONE;
 671
 672         if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
 673                 i2c->cmd_err = -ENXIO;
 674         else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
 675                     MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
 676                     MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
 677                 /* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
 678                 i2c->cmd_err = -EIO;
 679
 680         writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
 681
 682         return IRQ_HANDLED;
 683 }
 684
 685 static const struct i2c_algorithm mxs_i2c_algo = {
 686         .master_xfer = mxs_i2c_xfer,
 687         .functionality = mxs_i2c_func,
 688 };
 689
 690 static void mxs_i2c_derive_timing(struct mxs_i2c_dev *i2c, uint32_t speed)
 691 {
 692         /* The I2C block clock runs at 24MHz */
 693         const uint32_t clk = 24000000;
 694         uint32_t divider;
 695         uint16_t high_count, low_count, rcv_count, xmit_count;
 696         uint32_t bus_free, leadin;
 697         struct device *dev = i2c->dev;
 698
 699         divider = DIV_ROUND_UP(clk, speed);
 700
 701         if (divider < 25) {
 702                 /*
 703                  * limit the divider, so that min(low_count, high_count)
 704                  * is >= 1
 705                  */
 706                 divider = 25;
 707                 dev_warn(dev,
 708                         "Speed too high (%u.%03u kHz), using %u.%03u kHz\n",
 709                         speed / 1000, speed % 1000,
 710                         clk / divider / 1000, clk / divider % 1000);
 711         } else if (divider > 1897) {
 712                 /*
 713                  * limit the divider, so that max(low_count, high_count)
 714                  * cannot exceed 1023
 715                  */
 716                 divider = 1897;
 717                 dev_warn(dev,
 718                         "Speed too low (%u.%03u kHz), using %u.%03u kHz\n",
 719                         speed / 1000, speed % 1000,
 720                         clk / divider / 1000, clk / divider % 1000);
 721         }
 722
 723         /*
 724          * The I2C spec specifies the following timing data:
 725          *                          standard mode  fast mode Bitfield name
 726          * tLOW (SCL LOW period)     4700 ns        1300 ns
 727          * tHIGH (SCL HIGH period)   4000 ns         600 ns
 728          * tSU;DAT (data setup time)  250 ns         100 ns
 729          * tHD;STA (START hold time) 4000 ns         600 ns
 730          * tBUF (bus free time)      4700 ns        1300 ns
 731          *
 732          * The hardware (of the i.MX28 at least) seems to add 2 additional
 733          * clock cycles to the low_count and 7 cycles to the high_count.
 734          * This is compensated for by subtracting the respective constants
 735          * from the values written to the timing registers.
 736          */
 737         if (speed > 100000) {
 738                 /* fast mode */
 739                 low_count = DIV_ROUND_CLOSEST(divider * 13, (13 + 6));
 740                 high_count = DIV_ROUND_CLOSEST(divider * 6, (13 + 6));
 741                 leadin = DIV_ROUND_UP(600 * (clk / 1000000), 1000);
 742                 bus_free = DIV_ROUND_UP(1300 * (clk / 1000000), 1000);
 743         } else {
 744                 /* normal mode */
 745                 low_count = DIV_ROUND_CLOSEST(divider * 47, (47 + 40));
 746                 high_count = DIV_ROUND_CLOSEST(divider * 40, (47 + 40));
 747                 leadin = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
 748                 bus_free = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
 749         }
 750         rcv_count = high_count * 3 / 8;
 751         xmit_count = low_count * 3 / 8;
 752
 753         dev_dbg(dev,
 754                 "speed=%u(actual %u) divider=%u low=%u high=%u xmit=%u rcv=%u leadin=%u bus_free=%u\n",
 755                 speed, clk / divider, divider, low_count, high_count,
 756                 xmit_count, rcv_count, leadin, bus_free);
 757
 758         low_count -= 2;
 759         high_count -= 7;
 760         i2c->timing0 = (high_count << 16) | rcv_count;
 761         i2c->timing1 = (low_count << 16) | xmit_count;
 762         i2c->timing2 = (bus_free << 16 | leadin);
 763 }
 764
 765 static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
 766 {
 767         uint32_t speed;
 768         struct device *dev = i2c->dev;
 769         struct device_node *node = dev->of_node;
 770         int ret;
 771
 772         ret = of_property_read_u32(node, "clock-frequency", &speed);
 773         if (ret) {
 774                 dev_warn(dev, "No I2C speed selected, using 100kHz\n");
 775                 speed = 100000;
 776         }
 777
 778         mxs_i2c_derive_timing(i2c, speed);
 779
 780         return 0;
 781 }
 782
 783 static struct platform_device_id mxs_i2c_devtype[] = {
 784         {
 785                 .name = "imx23-i2c",
 786                 .driver_data = MXS_I2C_V1,
 787         }, {
 788                 .name = "imx28-i2c",
 789                 .driver_data = MXS_I2C_V2,
 790         }, { /* sentinel */ }
 791 };
 792 MODULE_DEVICE_TABLE(platform, mxs_i2c_devtype);
 793
 794 static const struct of_device_id mxs_i2c_dt_ids[] = {
 795         { .compatible = "fsl,imx23-i2c", .data = &mxs_i2c_devtype[0], },
 796         { .compatible = "fsl,imx28-i2c", .data = &mxs_i2c_devtype[1], },
 797         { /* sentinel */ }
 798 };
 799 MODULE_DEVICE_TABLE(of, mxs_i2c_dt_ids);
 800
 801 static int mxs_i2c_probe(struct platform_device *pdev)
 802 {
 803         const struct of_device_id *of_id =
 804                                 of_match_device(mxs_i2c_dt_ids, &pdev->dev);
 805         struct device *dev = &pdev->dev;
 806         struct mxs_i2c_dev *i2c;
 807         struct i2c_adapter *adap;
 808         struct resource *res;
 809         resource_size_t res_size;
 810         int err, irq;
 811
 812         i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
 813         if (!i2c)
 814                 return -ENOMEM;
 815
 816         if (of_id) {
 817                 const struct platform_device_id *device_id = of_id->data;
 818                 i2c->dev_type = device_id->driver_data;
 819         }
 820
 821         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 822         irq = platform_get_irq(pdev, 0);
 823
 824         if (!res || irq < 0)
 825                 return -ENOENT;
 826
 827         res_size = resource_size(res);
 828         if (!devm_request_mem_region(dev, res->start, res_size, res->name))
 829                 return -EBUSY;
 830
 831         i2c->regs = devm_ioremap_nocache(dev, res->start, res_size);
 832         if (!i2c->regs)
 833                 return -EBUSY;
 834
 835         err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
 836         if (err)
 837                 return err;
 838
 839         i2c->dev = dev;
 840
 841         init_completion(&i2c->cmd_complete);
 842
 843         if (dev->of_node) {
 844                 err = mxs_i2c_get_ofdata(i2c);
 845                 if (err)
 846                         return err;
 847         }
 848
 849         /* Setup the DMA */
 850         i2c->dmach = dma_request_slave_channel(dev, "rx-tx");
 851         if (!i2c->dmach) {
 852                 dev_err(dev, "Failed to request dma\n");
 853                 return -ENODEV;
 854         }
 855
 856         platform_set_drvdata(pdev, i2c);
 857
 858         /* Do reset to enforce correct startup after pinmuxing */
 859         err = mxs_i2c_reset(i2c);
 860         if (err)
 861                 return err;
 862
 863         adap = &i2c->adapter;
 864         strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
 865         adap->owner = THIS_MODULE;
 866         adap->algo = &mxs_i2c_algo;
 867         adap->dev.parent = dev;
 868         adap->nr = pdev->id;
 869         adap->dev.of_node = pdev->dev.of_node;
 870         i2c_set_adapdata(adap, i2c);
 871         err = i2c_add_numbered_adapter(adap);
 872         if (err) {
 873                 dev_err(dev, "Failed to add adapter (%d)\n", err);
 874                 writel(MXS_I2C_CTRL0_SFTRST,
 875                                 i2c->regs + MXS_I2C_CTRL0_SET);
 876                 return err;
 877         }
 878
 879         return 0;
 880 }
 881
 882 static int mxs_i2c_remove(struct platform_device *pdev)
 883 {
 884         struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
 885
 886         i2c_del_adapter(&i2c->adapter);
 887
 888         if (i2c->dmach)
 889                 dma_release_channel(i2c->dmach);
 890
 891         writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
 892
 893         return 0;
 894 }
 895
 896 static struct platform_driver mxs_i2c_driver = {
 897         .driver = {
 898                    .name = DRIVER_NAME,
 899                    .owner = THIS_MODULE,
 900                    .of_match_table = mxs_i2c_dt_ids,
 901                    },
 902         .remove = mxs_i2c_remove,
 903 };
 904
 905 static int __init mxs_i2c_init(void)
 906 {
 907         return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe);
 908 }
 909 subsys_initcall(mxs_i2c_init);
 910
 911 static void __exit mxs_i2c_exit(void)
 912 {
 913         platform_driver_unregister(&mxs_i2c_driver);
 914 }
 915 module_exit(mxs_i2c_exit);
 916
 917 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
 918 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
 919 MODULE_DESCRIPTION("MXS I2C Bus Driver");
 920 MODULE_LICENSE("GPL");
 921 MODULE_ALIAS("platform:" DRIVER_NAME);