drivers/i2c/busses/i2c-mxs.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
mxs_i2c_reset
mxs_i2c_dma_finish
mxs_i2c_dma_irq_callback
mxs_i2c_dma_setup_xfer
mxs_i2c_pio_wait_xfer_end
mxs_i2c_pio_check_error_state
mxs_i2c_pio_trigger_cmd
mxs_i2c_pio_trigger_write_cmd
mxs_i2c_pio_setup_xfer
mxs_i2c_xfer_msg
mxs_i2c_xfer
mxs_i2c_func
mxs_i2c_isr
mxs_i2c_derive_timing
mxs_i2c_get_ofdata
mxs_i2c_probe
mxs_i2c_remove
mxs_i2c_init
mxs_i2c_exit
   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Freescale MXS I2C bus driver
   4  *
   5  * Copyright (C) 2012-2013 Marek Vasut <marex@denx.de>
   6  * Copyright (C) 2011-2012 Wolfram Sang, Pengutronix e.K.
   7  *
   8  * based on a (non-working) driver which was:
   9  *
  10  * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
  11  */
  12 
  13 #include <linux/slab.h>
  14 #include <linux/device.h>
  15 #include <linux/module.h>
  16 #include <linux/i2c.h>
  17 #include <linux/err.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/completion.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/io.h>
  23 #include <linux/stmp_device.h>
  24 #include <linux/of.h>
  25 #include <linux/of_device.h>
  26 #include <linux/dma-mapping.h>
  27 #include <linux/dmaengine.h>
  28 
  29 #define DRIVER_NAME "mxs-i2c"
  30 
  31 #define MXS_I2C_CTRL0           (0x00)
  32 #define MXS_I2C_CTRL0_SET       (0x04)
  33 #define MXS_I2C_CTRL0_CLR       (0x08)
  34 
  35 #define MXS_I2C_CTRL0_SFTRST                    0x80000000
  36 #define MXS_I2C_CTRL0_RUN                       0x20000000
  37 #define MXS_I2C_CTRL0_SEND_NAK_ON_LAST          0x02000000
  38 #define MXS_I2C_CTRL0_PIO_MODE                  0x01000000
  39 #define MXS_I2C_CTRL0_RETAIN_CLOCK              0x00200000
  40 #define MXS_I2C_CTRL0_POST_SEND_STOP            0x00100000
  41 #define MXS_I2C_CTRL0_PRE_SEND_START            0x00080000
  42 #define MXS_I2C_CTRL0_MASTER_MODE               0x00020000
  43 #define MXS_I2C_CTRL0_DIRECTION                 0x00010000
  44 #define MXS_I2C_CTRL0_XFER_COUNT(v)             ((v) & 0x0000FFFF)
  45 
  46 #define MXS_I2C_TIMING0         (0x10)
  47 #define MXS_I2C_TIMING1         (0x20)
  48 #define MXS_I2C_TIMING2         (0x30)
  49 
  50 #define MXS_I2C_CTRL1           (0x40)
  51 #define MXS_I2C_CTRL1_SET       (0x44)
  52 #define MXS_I2C_CTRL1_CLR       (0x48)
  53 
  54 #define MXS_I2C_CTRL1_CLR_GOT_A_NAK             0x10000000
  55 #define MXS_I2C_CTRL1_BUS_FREE_IRQ              0x80
  56 #define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ     0x40
  57 #define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ          0x20
  58 #define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ    0x10
  59 #define MXS_I2C_CTRL1_EARLY_TERM_IRQ            0x08
  60 #define MXS_I2C_CTRL1_MASTER_LOSS_IRQ           0x04
  61 #define MXS_I2C_CTRL1_SLAVE_STOP_IRQ            0x02
  62 #define MXS_I2C_CTRL1_SLAVE_IRQ                 0x01
  63 
  64 #define MXS_I2C_STAT            (0x50)
  65 #define MXS_I2C_STAT_GOT_A_NAK                  0x10000000
  66 #define MXS_I2C_STAT_BUS_BUSY                   0x00000800
  67 #define MXS_I2C_STAT_CLK_GEN_BUSY               0x00000400
  68 
  69 #define MXS_I2C_DATA(i2c)       ((i2c->dev_type == MXS_I2C_V1) ? 0x60 : 0xa0)
  70 
  71 #define MXS_I2C_DEBUG0_CLR(i2c) ((i2c->dev_type == MXS_I2C_V1) ? 0x78 : 0xb8)
  72 
  73 #define MXS_I2C_DEBUG0_DMAREQ   0x80000000
  74 
  75 #define MXS_I2C_IRQ_MASK        (MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
  76                                  MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
  77                                  MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
  78                                  MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
  79                                  MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
  80                                  MXS_I2C_CTRL1_SLAVE_IRQ)
  81 
  82 
  83 #define MXS_CMD_I2C_SELECT      (MXS_I2C_CTRL0_RETAIN_CLOCK |   \
  84                                  MXS_I2C_CTRL0_PRE_SEND_START | \
  85                                  MXS_I2C_CTRL0_MASTER_MODE |    \
  86                                  MXS_I2C_CTRL0_DIRECTION |      \
  87                                  MXS_I2C_CTRL0_XFER_COUNT(1))
  88 
  89 #define MXS_CMD_I2C_WRITE       (MXS_I2C_CTRL0_PRE_SEND_START | \
  90                                  MXS_I2C_CTRL0_MASTER_MODE |    \
  91                                  MXS_I2C_CTRL0_DIRECTION)
  92 
  93 #define MXS_CMD_I2C_READ        (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
  94                                  MXS_I2C_CTRL0_MASTER_MODE)
  95 
  96 enum mxs_i2c_devtype {
  97         MXS_I2C_UNKNOWN = 0,
  98         MXS_I2C_V1,
  99         MXS_I2C_V2,
 100 };
 101 
 102 /**
 103  * struct mxs_i2c_dev - per device, private MXS-I2C data
 104  *
 105  * @dev: driver model device node
 106  * @dev_type: distinguish i.MX23/i.MX28 features
 107  * @regs: IO registers pointer
 108  * @cmd_complete: completion object for transaction wait
 109  * @cmd_err: error code for last transaction
 110  * @adapter: i2c subsystem adapter node
 111  */
 112 struct mxs_i2c_dev {
 113         struct device *dev;
 114         enum mxs_i2c_devtype dev_type;
 115         void __iomem *regs;
 116         struct completion cmd_complete;
 117         int cmd_err;
 118         struct i2c_adapter adapter;
 119 
 120         uint32_t timing0;
 121         uint32_t timing1;
 122         uint32_t timing2;
 123 
 124         /* DMA support components */
 125         struct dma_chan                 *dmach;
 126         uint32_t                        pio_data[2];
 127         uint32_t                        addr_data;
 128         struct scatterlist              sg_io[2];
 129         bool                            dma_read;
 130 };
 131 
 132 static int mxs_i2c_reset(struct mxs_i2c_dev *i2c)
 133 {
 134         int ret = stmp_reset_block(i2c->regs);
 135         if (ret)
 136                 return ret;
 137 
 138         /*
 139          * Configure timing for the I2C block. The I2C TIMING2 register has to
 140          * be programmed with this particular magic number. The rest is derived
 141          * from the XTAL speed and requested I2C speed.
 142          *
 143          * For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
 144          */
 145         writel(i2c->timing0, i2c->regs + MXS_I2C_TIMING0);
 146         writel(i2c->timing1, i2c->regs + MXS_I2C_TIMING1);
 147         writel(i2c->timing2, i2c->regs + MXS_I2C_TIMING2);
 148 
 149         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
 150 
 151         return 0;
 152 }
 153 
 154 static void mxs_i2c_dma_finish(struct mxs_i2c_dev *i2c)
 155 {
 156         if (i2c->dma_read) {
 157                 dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 158                 dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 159         } else {
 160                 dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 161         }
 162 }
 163 
 164 static void mxs_i2c_dma_irq_callback(void *param)
 165 {
 166         struct mxs_i2c_dev *i2c = param;
 167 
 168         complete(&i2c->cmd_complete);
 169         mxs_i2c_dma_finish(i2c);
 170 }
 171 
 172 static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
 173                         struct i2c_msg *msg, uint32_t flags)
 174 {
 175         struct dma_async_tx_descriptor *desc;
 176         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 177 
 178         i2c->addr_data = i2c_8bit_addr_from_msg(msg);
 179 
 180         if (msg->flags & I2C_M_RD) {
 181                 i2c->dma_read = true;
 182 
 183                 /*
 184                  * SELECT command.
 185                  */
 186 
 187                 /* Queue the PIO register write transfer. */
 188                 i2c->pio_data[0] = MXS_CMD_I2C_SELECT;
 189                 desc = dmaengine_prep_slave_sg(i2c->dmach,
 190                                         (struct scatterlist *)&i2c->pio_data[0],
 191                                         1, DMA_TRANS_NONE, 0);
 192                 if (!desc) {
 193                         dev_err(i2c->dev,
 194                                 "Failed to get PIO reg. write descriptor.\n");
 195                         goto select_init_pio_fail;
 196                 }
 197 
 198                 /* Queue the DMA data transfer. */
 199                 sg_init_one(&i2c->sg_io[0], &i2c->addr_data, 1);
 200                 dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 201                 desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
 202                                         DMA_MEM_TO_DEV,
 203                                         DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 204                 if (!desc) {
 205                         dev_err(i2c->dev,
 206                                 "Failed to get DMA data write descriptor.\n");
 207                         goto select_init_dma_fail;
 208                 }
 209 
 210                 /*
 211                  * READ command.
 212                  */
 213 
 214                 /* Queue the PIO register write transfer. */
 215                 i2c->pio_data[1] = flags | MXS_CMD_I2C_READ |
 216                                 MXS_I2C_CTRL0_XFER_COUNT(msg->len);
 217                 desc = dmaengine_prep_slave_sg(i2c->dmach,
 218                                         (struct scatterlist *)&i2c->pio_data[1],
 219                                         1, DMA_TRANS_NONE, DMA_PREP_INTERRUPT);
 220                 if (!desc) {
 221                         dev_err(i2c->dev,
 222                                 "Failed to get PIO reg. write descriptor.\n");
 223                         goto select_init_dma_fail;
 224                 }
 225 
 226                 /* Queue the DMA data transfer. */
 227                 sg_init_one(&i2c->sg_io[1], msg->buf, msg->len);
 228                 dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 229                 desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
 230                                         DMA_DEV_TO_MEM,
 231                                         DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 232                 if (!desc) {
 233                         dev_err(i2c->dev,
 234                                 "Failed to get DMA data write descriptor.\n");
 235                         goto read_init_dma_fail;
 236                 }
 237         } else {
 238                 i2c->dma_read = false;
 239 
 240                 /*
 241                  * WRITE command.
 242                  */
 243 
 244                 /* Queue the PIO register write transfer. */
 245                 i2c->pio_data[0] = flags | MXS_CMD_I2C_WRITE |
 246                                 MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1);
 247                 desc = dmaengine_prep_slave_sg(i2c->dmach,
 248                                         (struct scatterlist *)&i2c->pio_data[0],
 249                                         1, DMA_TRANS_NONE, 0);
 250                 if (!desc) {
 251                         dev_err(i2c->dev,
 252                                 "Failed to get PIO reg. write descriptor.\n");
 253                         goto write_init_pio_fail;
 254                 }
 255 
 256                 /* Queue the DMA data transfer. */
 257                 sg_init_table(i2c->sg_io, 2);
 258                 sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1);
 259                 sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len);
 260                 dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 261                 desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
 262                                         DMA_MEM_TO_DEV,
 263                                         DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 264                 if (!desc) {
 265                         dev_err(i2c->dev,
 266                                 "Failed to get DMA data write descriptor.\n");
 267                         goto write_init_dma_fail;
 268                 }
 269         }
 270 
 271         /*
 272          * The last descriptor must have this callback,
 273          * to finish the DMA transaction.
 274          */
 275         desc->callback = mxs_i2c_dma_irq_callback;
 276         desc->callback_param = i2c;
 277 
 278         /* Start the transfer. */
 279         dmaengine_submit(desc);
 280         dma_async_issue_pending(i2c->dmach);
 281         return 0;
 282 
 283 /* Read failpath. */
 284 read_init_dma_fail:
 285         dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
 286 select_init_dma_fail:
 287         dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
 288 select_init_pio_fail:
 289         dmaengine_terminate_all(i2c->dmach);
 290         return -EINVAL;
 291 
 292 /* Write failpath. */
 293 write_init_dma_fail:
 294         dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
 295 write_init_pio_fail:
 296         dmaengine_terminate_all(i2c->dmach);
 297         return -EINVAL;
 298 }
 299 
 300 static int mxs_i2c_pio_wait_xfer_end(struct mxs_i2c_dev *i2c)
 301 {
 302         unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 303 
 304         while (readl(i2c->regs + MXS_I2C_CTRL0) & MXS_I2C_CTRL0_RUN) {
 305                 if (readl(i2c->regs + MXS_I2C_CTRL1) &
 306                                 MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
 307                         return -ENXIO;
 308                 if (time_after(jiffies, timeout))
 309                         return -ETIMEDOUT;
 310                 cond_resched();
 311         }
 312 
 313         return 0;
 314 }
 315 
 316 static int mxs_i2c_pio_check_error_state(struct mxs_i2c_dev *i2c)
 317 {
 318         u32 state;
 319 
 320         state = readl(i2c->regs + MXS_I2C_CTRL1_CLR) & MXS_I2C_IRQ_MASK;
 321 
 322         if (state & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
 323                 i2c->cmd_err = -ENXIO;
 324         else if (state & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
 325                           MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
 326                           MXS_I2C_CTRL1_SLAVE_STOP_IRQ |
 327                           MXS_I2C_CTRL1_SLAVE_IRQ))
 328                 i2c->cmd_err = -EIO;
 329 
 330         return i2c->cmd_err;
 331 }
 332 
 333 static void mxs_i2c_pio_trigger_cmd(struct mxs_i2c_dev *i2c, u32 cmd)
 334 {
 335         u32 reg;
 336 
 337         writel(cmd, i2c->regs + MXS_I2C_CTRL0);
 338 
 339         /* readback makes sure the write is latched into hardware */
 340         reg = readl(i2c->regs + MXS_I2C_CTRL0);
 341         reg |= MXS_I2C_CTRL0_RUN;
 342         writel(reg, i2c->regs + MXS_I2C_CTRL0);
 343 }
 344 
 345 /*
 346  * Start WRITE transaction on the I2C bus. By studying i.MX23 datasheet,
 347  * CTRL0::PIO_MODE bit description clarifies the order in which the registers
 348  * must be written during PIO mode operation. First, the CTRL0 register has
 349  * to be programmed with all the necessary bits but the RUN bit. Then the
 350  * payload has to be written into the DATA register. Finally, the transmission
 351  * is executed by setting the RUN bit in CTRL0.
 352  */
 353 static void mxs_i2c_pio_trigger_write_cmd(struct mxs_i2c_dev *i2c, u32 cmd,
 354                                           u32 data)
 355 {
 356         writel(cmd, i2c->regs + MXS_I2C_CTRL0);
 357 
 358         if (i2c->dev_type == MXS_I2C_V1)
 359                 writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_SET);
 360 
 361         writel(data, i2c->regs + MXS_I2C_DATA(i2c));
 362         writel(MXS_I2C_CTRL0_RUN, i2c->regs + MXS_I2C_CTRL0_SET);
 363 }
 364 
 365 static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
 366                         struct i2c_msg *msg, uint32_t flags)
 367 {
 368         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 369         uint32_t addr_data = i2c_8bit_addr_from_msg(msg);
 370         uint32_t data = 0;
 371         int i, ret, xlen = 0, xmit = 0;
 372         uint32_t start;
 373 
 374         /* Mute IRQs coming from this block. */
 375         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_CLR);
 376 
 377         /*
 378          * MX23 idea:
 379          * - Enable CTRL0::PIO_MODE (1 << 24)
 380          * - Enable CTRL1::ACK_MODE (1 << 27)
 381          *
 382          * WARNING! The MX23 is broken in some way, even if it claims
 383          * to support PIO, when we try to transfer any amount of data
 384          * that is not aligned to 4 bytes, the DMA engine will have
 385          * bits in DEBUG1::DMA_BYTES_ENABLES still set even after the
 386          * transfer. This in turn will mess up the next transfer as
 387          * the block it emit one byte write onto the bus terminated
 388          * with a NAK+STOP. A possible workaround is to reset the IP
 389          * block after every PIO transmission, which might just work.
 390          *
 391          * NOTE: The CTRL0::PIO_MODE description is important, since
 392          * it outlines how the PIO mode is really supposed to work.
 393          */
 394         if (msg->flags & I2C_M_RD) {
 395                 /*
 396                  * PIO READ transfer:
 397                  *
 398                  * This transfer MUST be limited to 4 bytes maximum. It is not
 399                  * possible to transfer more than four bytes via PIO, since we
 400                  * can not in any way make sure we can read the data from the
 401                  * DATA register fast enough. Besides, the RX FIFO is only four
 402                  * bytes deep, thus we can only really read up to four bytes at
 403                  * time. Finally, there is no bit indicating us that new data
 404                  * arrived at the FIFO and can thus be fetched from the DATA
 405                  * register.
 406                  */
 407                 BUG_ON(msg->len > 4);
 408 
 409                 /* SELECT command. */
 410                 mxs_i2c_pio_trigger_write_cmd(i2c, MXS_CMD_I2C_SELECT,
 411                                               addr_data);
 412 
 413                 ret = mxs_i2c_pio_wait_xfer_end(i2c);
 414                 if (ret) {
 415                         dev_dbg(i2c->dev,
 416                                 "PIO: Failed to send SELECT command!\n");
 417                         goto cleanup;
 418                 }
 419 
 420                 /* READ command. */
 421                 mxs_i2c_pio_trigger_cmd(i2c,
 422                                         MXS_CMD_I2C_READ | flags |
 423                                         MXS_I2C_CTRL0_XFER_COUNT(msg->len));
 424 
 425                 ret = mxs_i2c_pio_wait_xfer_end(i2c);
 426                 if (ret) {
 427                         dev_dbg(i2c->dev,
 428                                 "PIO: Failed to send READ command!\n");
 429                         goto cleanup;
 430                 }
 431 
 432                 data = readl(i2c->regs + MXS_I2C_DATA(i2c));
 433                 for (i = 0; i < msg->len; i++) {
 434                         msg->buf[i] = data & 0xff;
 435                         data >>= 8;
 436                 }
 437         } else {
 438                 /*
 439                  * PIO WRITE transfer:
 440                  *
 441                  * The code below implements clock stretching to circumvent
 442                  * the possibility of kernel not being able to supply data
 443                  * fast enough. It is possible to transfer arbitrary amount
 444                  * of data using PIO write.
 445                  */
 446 
 447                 /*
 448                  * The LSB of data buffer is the first byte blasted across
 449                  * the bus. Higher order bytes follow. Thus the following
 450                  * filling schematic.
 451                  */
 452 
 453                 data = addr_data << 24;
 454 
 455                 /* Start the transfer with START condition. */
 456                 start = MXS_I2C_CTRL0_PRE_SEND_START;
 457 
 458                 /* If the transfer is long, use clock stretching. */
 459                 if (msg->len > 3)
 460                         start |= MXS_I2C_CTRL0_RETAIN_CLOCK;
 461 
 462                 for (i = 0; i < msg->len; i++) {
 463                         data >>= 8;
 464                         data |= (msg->buf[i] << 24);
 465 
 466                         xmit = 0;
 467 
 468                         /* This is the last transfer of the message. */
 469                         if (i + 1 == msg->len) {
 470                                 /* Add optional STOP flag. */
 471                                 start |= flags;
 472                                 /* Remove RETAIN_CLOCK bit. */
 473                                 start &= ~MXS_I2C_CTRL0_RETAIN_CLOCK;
 474                                 xmit = 1;
 475                         }
 476 
 477                         /* Four bytes are ready in the "data" variable. */
 478                         if ((i & 3) == 2)
 479                                 xmit = 1;
 480 
 481                         /* Nothing interesting happened, continue stuffing. */
 482                         if (!xmit)
 483                                 continue;
 484 
 485                         /*
 486                          * Compute the size of the transfer and shift the
 487                          * data accordingly.
 488                          *
 489                          * i = (4k + 0) .... xlen = 2
 490                          * i = (4k + 1) .... xlen = 3
 491                          * i = (4k + 2) .... xlen = 4
 492                          * i = (4k + 3) .... xlen = 1
 493                          */
 494 
 495                         if ((i % 4) == 3)
 496                                 xlen = 1;
 497                         else
 498                                 xlen = (i % 4) + 2;
 499 
 500                         data >>= (4 - xlen) * 8;
 501 
 502                         dev_dbg(i2c->dev,
 503                                 "PIO: len=%i pos=%i total=%i [W%s%s%s]\n",
 504                                 xlen, i, msg->len,
 505                                 start & MXS_I2C_CTRL0_PRE_SEND_START ? "S" : "",
 506                                 start & MXS_I2C_CTRL0_POST_SEND_STOP ? "E" : "",
 507                                 start & MXS_I2C_CTRL0_RETAIN_CLOCK ? "C" : "");
 508 
 509                         writel(MXS_I2C_DEBUG0_DMAREQ,
 510                                i2c->regs + MXS_I2C_DEBUG0_CLR(i2c));
 511 
 512                         mxs_i2c_pio_trigger_write_cmd(i2c,
 513                                 start | MXS_I2C_CTRL0_MASTER_MODE |
 514                                 MXS_I2C_CTRL0_DIRECTION |
 515                                 MXS_I2C_CTRL0_XFER_COUNT(xlen), data);
 516 
 517                         /* The START condition is sent only once. */
 518                         start &= ~MXS_I2C_CTRL0_PRE_SEND_START;
 519 
 520                         /* Wait for the end of the transfer. */
 521                         ret = mxs_i2c_pio_wait_xfer_end(i2c);
 522                         if (ret) {
 523                                 dev_dbg(i2c->dev,
 524                                         "PIO: Failed to finish WRITE cmd!\n");
 525                                 break;
 526                         }
 527 
 528                         /* Check NAK here. */
 529                         ret = readl(i2c->regs + MXS_I2C_STAT) &
 530                                     MXS_I2C_STAT_GOT_A_NAK;
 531                         if (ret) {
 532                                 ret = -ENXIO;
 533                                 goto cleanup;
 534                         }
 535                 }
 536         }
 537 
 538         /* make sure we capture any occurred error into cmd_err */
 539         ret = mxs_i2c_pio_check_error_state(i2c);
 540 
 541 cleanup:
 542         /* Clear any dangling IRQs and re-enable interrupts. */
 543         writel(MXS_I2C_IRQ_MASK, i2c->regs + MXS_I2C_CTRL1_CLR);
 544         writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
 545 
 546         /* Clear the PIO_MODE on i.MX23 */
 547         if (i2c->dev_type == MXS_I2C_V1)
 548                 writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_CLR);
 549 
 550         return ret;
 551 }
 552 
 553 /*
 554  * Low level master read/write transaction.
 555  */
 556 static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
 557                                 int stop)
 558 {
 559         struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
 560         int ret;
 561         int flags;
 562         int use_pio = 0;
 563         unsigned long time_left;
 564 
 565         flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
 566 
 567         dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
 568                 msg->addr, msg->len, msg->flags, stop);
 569 
 570         /*
 571          * The MX28 I2C IP block can only do PIO READ for transfer of to up
 572          * 4 bytes of length. The write transfer is not limited as it can use
 573          * clock stretching to avoid FIFO underruns.
 574          */
 575         if ((msg->flags & I2C_M_RD) && (msg->len <= 4))
 576                 use_pio = 1;
 577         if (!(msg->flags & I2C_M_RD) && (msg->len < 7))
 578                 use_pio = 1;
 579 
 580         i2c->cmd_err = 0;
 581         if (use_pio) {
 582                 ret = mxs_i2c_pio_setup_xfer(adap, msg, flags);
 583                 /* No need to reset the block if NAK was received. */
 584                 if (ret && (ret != -ENXIO))
 585                         mxs_i2c_reset(i2c);
 586         } else {
 587                 reinit_completion(&i2c->cmd_complete);
 588                 ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
 589                 if (ret)
 590                         return ret;
 591 
 592                 time_left = wait_for_completion_timeout(&i2c->cmd_complete,
 593                                                 msecs_to_jiffies(1000));
 594                 if (!time_left)
 595                         goto timeout;
 596 
 597                 ret = i2c->cmd_err;
 598         }
 599 
 600         if (ret == -ENXIO) {
 601                 /*
 602                  * If the transfer fails with a NAK from the slave the
 603                  * controller halts until it gets told to return to idle state.
 604                  */
 605                 writel(MXS_I2C_CTRL1_CLR_GOT_A_NAK,
 606                        i2c->regs + MXS_I2C_CTRL1_SET);
 607         }
 608 
 609         /*
 610          * WARNING!
 611          * The i.MX23 is strange. After each and every operation, it's I2C IP
 612          * block must be reset, otherwise the IP block will misbehave. This can
 613          * be observed on the bus by the block sending out one single byte onto
 614          * the bus. In case such an error happens, bit 27 will be set in the
 615          * DEBUG0 register. This bit is not documented in the i.MX23 datasheet
 616          * and is marked as "TBD" instead. To reset this bit to a correct state,
 617          * reset the whole block. Since the block reset does not take long, do
 618          * reset the block after every transfer to play safe.
 619          */
 620         if (i2c->dev_type == MXS_I2C_V1)
 621                 mxs_i2c_reset(i2c);
 622 
 623         dev_dbg(i2c->dev, "Done with err=%d\n", ret);
 624 
 625         return ret;
 626 
 627 timeout:
 628         dev_dbg(i2c->dev, "Timeout!\n");
 629         mxs_i2c_dma_finish(i2c);
 630         ret = mxs_i2c_reset(i2c);
 631         if (ret)
 632                 return ret;
 633 
 634         return -ETIMEDOUT;
 635 }
 636 
 637 static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 638                         int num)
 639 {
 640         int i;
 641         int err;
 642 
 643         for (i = 0; i < num; i++) {
 644                 err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
 645                 if (err)
 646                         return err;
 647         }
 648 
 649         return num;
 650 }
 651 
 652 static u32 mxs_i2c_func(struct i2c_adapter *adap)
 653 {
 654         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 655 }
 656 
 657 static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
 658 {
 659         struct mxs_i2c_dev *i2c = dev_id;
 660         u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
 661 
 662         if (!stat)
 663                 return IRQ_NONE;
 664 
 665         if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
 666                 i2c->cmd_err = -ENXIO;
 667         else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
 668                     MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
 669                     MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
 670                 /* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
 671                 i2c->cmd_err = -EIO;
 672 
 673         writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
 674 
 675         return IRQ_HANDLED;
 676 }
 677 
 678 static const struct i2c_algorithm mxs_i2c_algo = {
 679         .master_xfer = mxs_i2c_xfer,
 680         .functionality = mxs_i2c_func,
 681 };
 682 
 683 static const struct i2c_adapter_quirks mxs_i2c_quirks = {
 684         .flags = I2C_AQ_NO_ZERO_LEN,
 685 };
 686 
 687 static void mxs_i2c_derive_timing(struct mxs_i2c_dev *i2c, uint32_t speed)
 688 {
 689         /* The I2C block clock runs at 24MHz */
 690         const uint32_t clk = 24000000;
 691         uint32_t divider;
 692         uint16_t high_count, low_count, rcv_count, xmit_count;
 693         uint32_t bus_free, leadin;
 694         struct device *dev = i2c->dev;
 695 
 696         divider = DIV_ROUND_UP(clk, speed);
 697 
 698         if (divider < 25) {
 699                 /*
 700                  * limit the divider, so that min(low_count, high_count)
 701                  * is >= 1
 702                  */
 703                 divider = 25;
 704                 dev_warn(dev,
 705                         "Speed too high (%u.%03u kHz), using %u.%03u kHz\n",
 706                         speed / 1000, speed % 1000,
 707                         clk / divider / 1000, clk / divider % 1000);
 708         } else if (divider > 1897) {
 709                 /*
 710                  * limit the divider, so that max(low_count, high_count)
 711                  * cannot exceed 1023
 712                  */
 713                 divider = 1897;
 714                 dev_warn(dev,
 715                         "Speed too low (%u.%03u kHz), using %u.%03u kHz\n",
 716                         speed / 1000, speed % 1000,
 717                         clk / divider / 1000, clk / divider % 1000);
 718         }
 719 
 720         /*
 721          * The I2C spec specifies the following timing data:
 722          *                          standard mode  fast mode Bitfield name
 723          * tLOW (SCL LOW period)     4700 ns        1300 ns
 724          * tHIGH (SCL HIGH period)   4000 ns         600 ns
 725          * tSU;DAT (data setup time)  250 ns         100 ns
 726          * tHD;STA (START hold time) 4000 ns         600 ns
 727          * tBUF (bus free time)      4700 ns        1300 ns
 728          *
 729          * The hardware (of the i.MX28 at least) seems to add 2 additional
 730          * clock cycles to the low_count and 7 cycles to the high_count.
 731          * This is compensated for by subtracting the respective constants
 732          * from the values written to the timing registers.
 733          */
 734         if (speed > 100000) {
 735                 /* fast mode */
 736                 low_count = DIV_ROUND_CLOSEST(divider * 13, (13 + 6));
 737                 high_count = DIV_ROUND_CLOSEST(divider * 6, (13 + 6));
 738                 leadin = DIV_ROUND_UP(600 * (clk / 1000000), 1000);
 739                 bus_free = DIV_ROUND_UP(1300 * (clk / 1000000), 1000);
 740         } else {
 741                 /* normal mode */
 742                 low_count = DIV_ROUND_CLOSEST(divider * 47, (47 + 40));
 743                 high_count = DIV_ROUND_CLOSEST(divider * 40, (47 + 40));
 744                 leadin = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
 745                 bus_free = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
 746         }
 747         rcv_count = high_count * 3 / 8;
 748         xmit_count = low_count * 3 / 8;
 749 
 750         dev_dbg(dev,
 751                 "speed=%u(actual %u) divider=%u low=%u high=%u xmit=%u rcv=%u leadin=%u bus_free=%u\n",
 752                 speed, clk / divider, divider, low_count, high_count,
 753                 xmit_count, rcv_count, leadin, bus_free);
 754 
 755         low_count -= 2;
 756         high_count -= 7;
 757         i2c->timing0 = (high_count << 16) | rcv_count;
 758         i2c->timing1 = (low_count << 16) | xmit_count;
 759         i2c->timing2 = (bus_free << 16 | leadin);
 760 }
 761 
 762 static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
 763 {
 764         uint32_t speed;
 765         struct device *dev = i2c->dev;
 766         struct device_node *node = dev->of_node;
 767         int ret;
 768 
 769         ret = of_property_read_u32(node, "clock-frequency", &speed);
 770         if (ret) {
 771                 dev_warn(dev, "No I2C speed selected, using 100kHz\n");
 772                 speed = 100000;
 773         }
 774 
 775         mxs_i2c_derive_timing(i2c, speed);
 776 
 777         return 0;
 778 }
 779 
 780 static const struct platform_device_id mxs_i2c_devtype[] = {
 781         {
 782                 .name = "imx23-i2c",
 783                 .driver_data = MXS_I2C_V1,
 784         }, {
 785                 .name = "imx28-i2c",
 786                 .driver_data = MXS_I2C_V2,
 787         }, { /* sentinel */ }
 788 };
 789 MODULE_DEVICE_TABLE(platform, mxs_i2c_devtype);
 790 
 791 static const struct of_device_id mxs_i2c_dt_ids[] = {
 792         { .compatible = "fsl,imx23-i2c", .data = &mxs_i2c_devtype[0], },
 793         { .compatible = "fsl,imx28-i2c", .data = &mxs_i2c_devtype[1], },
 794         { /* sentinel */ }
 795 };
 796 MODULE_DEVICE_TABLE(of, mxs_i2c_dt_ids);
 797 
 798 static int mxs_i2c_probe(struct platform_device *pdev)
 799 {
 800         const struct of_device_id *of_id =
 801                                 of_match_device(mxs_i2c_dt_ids, &pdev->dev);
 802         struct device *dev = &pdev->dev;
 803         struct mxs_i2c_dev *i2c;
 804         struct i2c_adapter *adap;
 805         int err, irq;
 806 
 807         i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
 808         if (!i2c)
 809                 return -ENOMEM;
 810 
 811         if (of_id) {
 812                 const struct platform_device_id *device_id = of_id->data;
 813                 i2c->dev_type = device_id->driver_data;
 814         }
 815 
 816         i2c->regs = devm_platform_ioremap_resource(pdev, 0);
 817         if (IS_ERR(i2c->regs))
 818                 return PTR_ERR(i2c->regs);
 819 
 820         irq = platform_get_irq(pdev, 0);
 821         if (irq < 0)
 822                 return irq;
 823 
 824         err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
 825         if (err)
 826                 return err;
 827 
 828         i2c->dev = dev;
 829 
 830         init_completion(&i2c->cmd_complete);
 831 
 832         if (dev->of_node) {
 833                 err = mxs_i2c_get_ofdata(i2c);
 834                 if (err)
 835                         return err;
 836         }
 837 
 838         /* Setup the DMA */
 839         i2c->dmach = dma_request_slave_channel(dev, "rx-tx");
 840         if (!i2c->dmach) {
 841                 dev_err(dev, "Failed to request dma\n");
 842                 return -ENODEV;
 843         }
 844 
 845         platform_set_drvdata(pdev, i2c);
 846 
 847         /* Do reset to enforce correct startup after pinmuxing */
 848         err = mxs_i2c_reset(i2c);
 849         if (err)
 850                 return err;
 851 
 852         adap = &i2c->adapter;
 853         strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
 854         adap->owner = THIS_MODULE;
 855         adap->algo = &mxs_i2c_algo;
 856         adap->quirks = &mxs_i2c_quirks;
 857         adap->dev.parent = dev;
 858         adap->nr = pdev->id;
 859         adap->dev.of_node = pdev->dev.of_node;
 860         i2c_set_adapdata(adap, i2c);
 861         err = i2c_add_numbered_adapter(adap);
 862         if (err) {
 863                 writel(MXS_I2C_CTRL0_SFTRST,
 864                                 i2c->regs + MXS_I2C_CTRL0_SET);
 865                 return err;
 866         }
 867 
 868         return 0;
 869 }
 870 
 871 static int mxs_i2c_remove(struct platform_device *pdev)
 872 {
 873         struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
 874 
 875         i2c_del_adapter(&i2c->adapter);
 876 
 877         if (i2c->dmach)
 878                 dma_release_channel(i2c->dmach);
 879 
 880         writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
 881 
 882         return 0;
 883 }
 884 
 885 static struct platform_driver mxs_i2c_driver = {
 886         .driver = {
 887                    .name = DRIVER_NAME,
 888                    .of_match_table = mxs_i2c_dt_ids,
 889                    },
 890         .probe = mxs_i2c_probe,
 891         .remove = mxs_i2c_remove,
 892 };
 893 
 894 static int __init mxs_i2c_init(void)
 895 {
 896         return platform_driver_register(&mxs_i2c_driver);
 897 }
 898 subsys_initcall(mxs_i2c_init);
 899 
 900 static void __exit mxs_i2c_exit(void)
 901 {
 902         platform_driver_unregister(&mxs_i2c_driver);
 903 }
 904 module_exit(mxs_i2c_exit);
 905 
 906 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
 907 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
 908 MODULE_DESCRIPTION("MXS I2C Bus Driver");
 909 MODULE_LICENSE("GPL");
 910 MODULE_ALIAS("platform:" DRIVER_NAME);
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/i2c/busses/i2c-mxs.c

DEFINITIONS
