drivers/i2c/busses/i2c-cadence.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * I2C bus driver for the Cadence I2C controller.
   4  *
   5  * Copyright (C) 2009 - 2014 Xilinx, Inc.
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/delay.h>
  10 #include <linux/i2c.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/of.h>
  16 #include <linux/pm_runtime.h>
  17
  18 /* Register offsets for the I2C device. */
  19 #define CDNS_I2C_CR_OFFSET              0x00 /* Control Register, RW */
  20 #define CDNS_I2C_SR_OFFSET              0x04 /* Status Register, RO */
  21 #define CDNS_I2C_ADDR_OFFSET            0x08 /* I2C Address Register, RW */
  22 #define CDNS_I2C_DATA_OFFSET            0x0C /* I2C Data Register, RW */
  23 #define CDNS_I2C_ISR_OFFSET             0x10 /* IRQ Status Register, RW */
  24 #define CDNS_I2C_XFER_SIZE_OFFSET       0x14 /* Transfer Size Register, RW */
  25 #define CDNS_I2C_TIME_OUT_OFFSET        0x1C /* Time Out Register, RW */
  26 #define CDNS_I2C_IER_OFFSET             0x24 /* IRQ Enable Register, WO */
  27 #define CDNS_I2C_IDR_OFFSET             0x28 /* IRQ Disable Register, WO */
  28
  29 /* Control Register Bit mask definitions */
  30 #define CDNS_I2C_CR_HOLD                BIT(4) /* Hold Bus bit */
  31 #define CDNS_I2C_CR_ACK_EN              BIT(3)
  32 #define CDNS_I2C_CR_NEA                 BIT(2)
  33 #define CDNS_I2C_CR_MS                  BIT(1)
  34 /* Read or Write Master transfer 0 = Transmitter, 1 = Receiver */
  35 #define CDNS_I2C_CR_RW                  BIT(0)
  36 /* 1 = Auto init FIFO to zeroes */
  37 #define CDNS_I2C_CR_CLR_FIFO            BIT(6)
  38 #define CDNS_I2C_CR_DIVA_SHIFT          14
  39 #define CDNS_I2C_CR_DIVA_MASK           (3 << CDNS_I2C_CR_DIVA_SHIFT)
  40 #define CDNS_I2C_CR_DIVB_SHIFT          8
  41 #define CDNS_I2C_CR_DIVB_MASK           (0x3f << CDNS_I2C_CR_DIVB_SHIFT)
  42
  43 /* Status Register Bit mask definitions */
  44 #define CDNS_I2C_SR_BA          BIT(8)
  45 #define CDNS_I2C_SR_RXDV        BIT(5)
  46
  47 /*
  48  * I2C Address Register Bit mask definitions
  49  * Normal addressing mode uses [6:0] bits. Extended addressing mode uses [9:0]
  50  * bits. A write access to this register always initiates a transfer if the I2C
  51  * is in master mode.
  52  */
  53 #define CDNS_I2C_ADDR_MASK      0x000003FF /* I2C Address Mask */
  54
  55 /*
  56  * I2C Interrupt Registers Bit mask definitions
  57  * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
  58  * bit definitions.
  59  */
  60 #define CDNS_I2C_IXR_ARB_LOST           BIT(9)
  61 #define CDNS_I2C_IXR_RX_UNF             BIT(7)
  62 #define CDNS_I2C_IXR_TX_OVF             BIT(6)
  63 #define CDNS_I2C_IXR_RX_OVF             BIT(5)
  64 #define CDNS_I2C_IXR_SLV_RDY            BIT(4)
  65 #define CDNS_I2C_IXR_TO                 BIT(3)
  66 #define CDNS_I2C_IXR_NACK               BIT(2)
  67 #define CDNS_I2C_IXR_DATA               BIT(1)
  68 #define CDNS_I2C_IXR_COMP               BIT(0)
  69
  70 #define CDNS_I2C_IXR_ALL_INTR_MASK      (CDNS_I2C_IXR_ARB_LOST | \
  71                                          CDNS_I2C_IXR_RX_UNF | \
  72                                          CDNS_I2C_IXR_TX_OVF | \
  73                                          CDNS_I2C_IXR_RX_OVF | \
  74                                          CDNS_I2C_IXR_SLV_RDY | \
  75                                          CDNS_I2C_IXR_TO | \
  76                                          CDNS_I2C_IXR_NACK | \
  77                                          CDNS_I2C_IXR_DATA | \
  78                                          CDNS_I2C_IXR_COMP)
  79
  80 #define CDNS_I2C_IXR_ERR_INTR_MASK      (CDNS_I2C_IXR_ARB_LOST | \
  81                                          CDNS_I2C_IXR_RX_UNF | \
  82                                          CDNS_I2C_IXR_TX_OVF | \
  83                                          CDNS_I2C_IXR_RX_OVF | \
  84                                          CDNS_I2C_IXR_NACK)
  85
  86 #define CDNS_I2C_ENABLED_INTR_MASK      (CDNS_I2C_IXR_ARB_LOST | \
  87                                          CDNS_I2C_IXR_RX_UNF | \
  88                                          CDNS_I2C_IXR_TX_OVF | \
  89                                          CDNS_I2C_IXR_RX_OVF | \
  90                                          CDNS_I2C_IXR_NACK | \
  91                                          CDNS_I2C_IXR_DATA | \
  92                                          CDNS_I2C_IXR_COMP)
  93
  94 #define CDNS_I2C_TIMEOUT                msecs_to_jiffies(1000)
  95 /* timeout for pm runtime autosuspend */
  96 #define CNDS_I2C_PM_TIMEOUT             1000    /* ms */
  97
  98 #define CDNS_I2C_FIFO_DEPTH             16
  99 /* FIFO depth at which the DATA interrupt occurs */
 100 #define CDNS_I2C_DATA_INTR_DEPTH        (CDNS_I2C_FIFO_DEPTH - 2)
 101 #define CDNS_I2C_MAX_TRANSFER_SIZE      255
 102 /* Transfer size in multiples of data interrupt depth */
 103 #define CDNS_I2C_TRANSFER_SIZE  (CDNS_I2C_MAX_TRANSFER_SIZE - 3)
 104
 105 #define DRIVER_NAME             "cdns-i2c"
 106
 107 #define CDNS_I2C_SPEED_MAX      400000
 108 #define CDNS_I2C_SPEED_DEFAULT  100000
 109
 110 #define CDNS_I2C_DIVA_MAX       4
 111 #define CDNS_I2C_DIVB_MAX       64
 112
 113 #define CDNS_I2C_TIMEOUT_MAX    0xFF
 114
 115 #define CDNS_I2C_BROKEN_HOLD_BIT        BIT(0)
 116
 117 #define cdns_i2c_readreg(offset)       readl_relaxed(id->membase + offset)
 118 #define cdns_i2c_writereg(val, offset) writel_relaxed(val, id->membase + offset)
 119
 120 /**
 121  * struct cdns_i2c - I2C device private data structure
 122  *
 123  * @dev:                Pointer to device structure
 124  * @membase:            Base address of the I2C device
 125  * @adap:               I2C adapter instance
 126  * @p_msg:              Message pointer
 127  * @err_status:         Error status in Interrupt Status Register
 128  * @xfer_done:          Transfer complete status
 129  * @p_send_buf:         Pointer to transmit buffer
 130  * @p_recv_buf:         Pointer to receive buffer
 131  * @send_count:         Number of bytes still expected to send
 132  * @recv_count:         Number of bytes still expected to receive
 133  * @curr_recv_count:    Number of bytes to be received in current transfer
 134  * @irq:                IRQ number
 135  * @input_clk:          Input clock to I2C controller
 136  * @i2c_clk:            Maximum I2C clock speed
 137  * @bus_hold_flag:      Flag used in repeated start for clearing HOLD bit
 138  * @clk:                Pointer to struct clk
 139  * @clk_rate_change_nb: Notifier block for clock rate changes
 140  * @quirks:             flag for broken hold bit usage in r1p10
 141  */
 142 struct cdns_i2c {
 143         struct device           *dev;
 144         void __iomem *membase;
 145         struct i2c_adapter adap;
 146         struct i2c_msg *p_msg;
 147         int err_status;
 148         struct completion xfer_done;
 149         unsigned char *p_send_buf;
 150         unsigned char *p_recv_buf;
 151         unsigned int send_count;
 152         unsigned int recv_count;
 153         unsigned int curr_recv_count;
 154         int irq;
 155         unsigned long input_clk;
 156         unsigned int i2c_clk;
 157         unsigned int bus_hold_flag;
 158         struct clk *clk;
 159         struct notifier_block clk_rate_change_nb;
 160         u32 quirks;
 161 };
 162
 163 struct cdns_platform_data {
 164         u32 quirks;
 165 };
 166
 167 #define to_cdns_i2c(_nb)        container_of(_nb, struct cdns_i2c, \
 168                                              clk_rate_change_nb)
 169
 170 /**
 171  * cdns_i2c_clear_bus_hold - Clear bus hold bit
 172  * @id: Pointer to driver data struct
 173  *
 174  * Helper to clear the controller's bus hold bit.
 175  */
 176 static void cdns_i2c_clear_bus_hold(struct cdns_i2c *id)
 177 {
 178         u32 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 179         if (reg & CDNS_I2C_CR_HOLD)
 180                 cdns_i2c_writereg(reg & ~CDNS_I2C_CR_HOLD, CDNS_I2C_CR_OFFSET);
 181 }
 182
 183 static inline bool cdns_is_holdquirk(struct cdns_i2c *id, bool hold_wrkaround)
 184 {
 185         return (hold_wrkaround &&
 186                 (id->curr_recv_count == CDNS_I2C_FIFO_DEPTH + 1));
 187 }
 188
 189 /**
 190  * cdns_i2c_isr - Interrupt handler for the I2C device
 191  * @irq:        irq number for the I2C device
 192  * @ptr:        void pointer to cdns_i2c structure
 193  *
 194  * This function handles the data interrupt, transfer complete interrupt and
 195  * the error interrupts of the I2C device.
 196  *
 197  * Return: IRQ_HANDLED always
 198  */
 199 static irqreturn_t cdns_i2c_isr(int irq, void *ptr)
 200 {
 201         unsigned int isr_status, avail_bytes, updatetx;
 202         unsigned int bytes_to_send;
 203         bool hold_quirk;
 204         struct cdns_i2c *id = ptr;
 205         /* Signal completion only after everything is updated */
 206         int done_flag = 0;
 207         irqreturn_t status = IRQ_NONE;
 208
 209         isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 210         cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 211
 212         /* Handling nack and arbitration lost interrupt */
 213         if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_ARB_LOST)) {
 214                 done_flag = 1;
 215                 status = IRQ_HANDLED;
 216         }
 217
 218         /*
 219          * Check if transfer size register needs to be updated again for a
 220          * large data receive operation.
 221          */
 222         updatetx = 0;
 223         if (id->recv_count > id->curr_recv_count)
 224                 updatetx = 1;
 225
 226         hold_quirk = (id->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx;
 227
 228         /* When receiving, handle data interrupt and completion interrupt */
 229         if (id->p_recv_buf &&
 230             ((isr_status & CDNS_I2C_IXR_COMP) ||
 231              (isr_status & CDNS_I2C_IXR_DATA))) {
 232                 /* Read data if receive data valid is set */
 233                 while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) &
 234                        CDNS_I2C_SR_RXDV) {
 235                         /*
 236                          * Clear hold bit that was set for FIFO control if
 237                          * RX data left is less than FIFO depth, unless
 238                          * repeated start is selected.
 239                          */
 240                         if ((id->recv_count < CDNS_I2C_FIFO_DEPTH) &&
 241                             !id->bus_hold_flag)
 242                                 cdns_i2c_clear_bus_hold(id);
 243
 244                         *(id->p_recv_buf)++ =
 245                                 cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
 246                         id->recv_count--;
 247                         id->curr_recv_count--;
 248
 249                         if (cdns_is_holdquirk(id, hold_quirk))
 250                                 break;
 251                 }
 252
 253                 /*
 254                  * The controller sends NACK to the slave when transfer size
 255                  * register reaches zero without considering the HOLD bit.
 256                  * This workaround is implemented for large data transfers to
 257                  * maintain transfer size non-zero while performing a large
 258                  * receive operation.
 259                  */
 260                 if (cdns_is_holdquirk(id, hold_quirk)) {
 261                         /* wait while fifo is full */
 262                         while (cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET) !=
 263                                (id->curr_recv_count - CDNS_I2C_FIFO_DEPTH))
 264                                 ;
 265
 266                         /*
 267                          * Check number of bytes to be received against maximum
 268                          * transfer size and update register accordingly.
 269                          */
 270                         if (((int)(id->recv_count) - CDNS_I2C_FIFO_DEPTH) >
 271                             CDNS_I2C_TRANSFER_SIZE) {
 272                                 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
 273                                                   CDNS_I2C_XFER_SIZE_OFFSET);
 274                                 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE +
 275                                                       CDNS_I2C_FIFO_DEPTH;
 276                         } else {
 277                                 cdns_i2c_writereg(id->recv_count -
 278                                                   CDNS_I2C_FIFO_DEPTH,
 279                                                   CDNS_I2C_XFER_SIZE_OFFSET);
 280                                 id->curr_recv_count = id->recv_count;
 281                         }
 282                 } else if (id->recv_count && !hold_quirk &&
 283                                                 !id->curr_recv_count) {
 284
 285                         /* Set the slave address in address register*/
 286                         cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
 287                                                 CDNS_I2C_ADDR_OFFSET);
 288
 289                         if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) {
 290                                 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
 291                                                 CDNS_I2C_XFER_SIZE_OFFSET);
 292                                 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE;
 293                         } else {
 294                                 cdns_i2c_writereg(id->recv_count,
 295                                                 CDNS_I2C_XFER_SIZE_OFFSET);
 296                                 id->curr_recv_count = id->recv_count;
 297                         }
 298                 }
 299
 300                 /* Clear hold (if not repeated start) and signal completion */
 301                 if ((isr_status & CDNS_I2C_IXR_COMP) && !id->recv_count) {
 302                         if (!id->bus_hold_flag)
 303                                 cdns_i2c_clear_bus_hold(id);
 304                         done_flag = 1;
 305                 }
 306
 307                 status = IRQ_HANDLED;
 308         }
 309
 310         /* When sending, handle transfer complete interrupt */
 311         if ((isr_status & CDNS_I2C_IXR_COMP) && !id->p_recv_buf) {
 312                 /*
 313                  * If there is more data to be sent, calculate the
 314                  * space available in FIFO and fill with that many bytes.
 315                  */
 316                 if (id->send_count) {
 317                         avail_bytes = CDNS_I2C_FIFO_DEPTH -
 318                             cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
 319                         if (id->send_count > avail_bytes)
 320                                 bytes_to_send = avail_bytes;
 321                         else
 322                                 bytes_to_send = id->send_count;
 323
 324                         while (bytes_to_send--) {
 325                                 cdns_i2c_writereg(
 326                                         (*(id->p_send_buf)++),
 327                                          CDNS_I2C_DATA_OFFSET);
 328                                 id->send_count--;
 329                         }
 330                 } else {
 331                         /*
 332                          * Signal the completion of transaction and
 333                          * clear the hold bus bit if there are no
 334                          * further messages to be processed.
 335                          */
 336                         done_flag = 1;
 337                 }
 338                 if (!id->send_count && !id->bus_hold_flag)
 339                         cdns_i2c_clear_bus_hold(id);
 340
 341                 status = IRQ_HANDLED;
 342         }
 343
 344         /* Update the status for errors */
 345         id->err_status = isr_status & CDNS_I2C_IXR_ERR_INTR_MASK;
 346         if (id->err_status)
 347                 status = IRQ_HANDLED;
 348
 349         if (done_flag)
 350                 complete(&id->xfer_done);
 351
 352         return status;
 353 }
 354
 355 /**
 356  * cdns_i2c_mrecv - Prepare and start a master receive operation
 357  * @id:         pointer to the i2c device structure
 358  */
 359 static void cdns_i2c_mrecv(struct cdns_i2c *id)
 360 {
 361         unsigned int ctrl_reg;
 362         unsigned int isr_status;
 363
 364         id->p_recv_buf = id->p_msg->buf;
 365         id->recv_count = id->p_msg->len;
 366
 367         /* Put the controller in master receive mode and clear the FIFO */
 368         ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 369         ctrl_reg |= CDNS_I2C_CR_RW | CDNS_I2C_CR_CLR_FIFO;
 370
 371         if (id->p_msg->flags & I2C_M_RECV_LEN)
 372                 id->recv_count = I2C_SMBUS_BLOCK_MAX + 1;
 373
 374         id->curr_recv_count = id->recv_count;
 375
 376         /*
 377          * Check for the message size against FIFO depth and set the
 378          * 'hold bus' bit if it is greater than FIFO depth.
 379          */
 380         if ((id->recv_count > CDNS_I2C_FIFO_DEPTH)  || id->bus_hold_flag)
 381                 ctrl_reg |= CDNS_I2C_CR_HOLD;
 382         else
 383                 ctrl_reg = ctrl_reg & ~CDNS_I2C_CR_HOLD;
 384
 385         cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 386
 387         /* Clear the interrupts in interrupt status register */
 388         isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 389         cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 390
 391         /*
 392          * The no. of bytes to receive is checked against the limit of
 393          * max transfer size. Set transfer size register with no of bytes
 394          * receive if it is less than transfer size and transfer size if
 395          * it is more. Enable the interrupts.
 396          */
 397         if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) {
 398                 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
 399                                   CDNS_I2C_XFER_SIZE_OFFSET);
 400                 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE;
 401         } else {
 402                 cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET);
 403         }
 404
 405         /* Set the slave address in address register - triggers operation */
 406         cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
 407                                                 CDNS_I2C_ADDR_OFFSET);
 408         /* Clear the bus hold flag if bytes to receive is less than FIFO size */
 409         if (!id->bus_hold_flag &&
 410                 ((id->p_msg->flags & I2C_M_RECV_LEN) != I2C_M_RECV_LEN) &&
 411                 (id->recv_count <= CDNS_I2C_FIFO_DEPTH))
 412                         cdns_i2c_clear_bus_hold(id);
 413         cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET);
 414 }
 415
 416 /**
 417  * cdns_i2c_msend - Prepare and start a master send operation
 418  * @id:         pointer to the i2c device
 419  */
 420 static void cdns_i2c_msend(struct cdns_i2c *id)
 421 {
 422         unsigned int avail_bytes;
 423         unsigned int bytes_to_send;
 424         unsigned int ctrl_reg;
 425         unsigned int isr_status;
 426
 427         id->p_recv_buf = NULL;
 428         id->p_send_buf = id->p_msg->buf;
 429         id->send_count = id->p_msg->len;
 430
 431         /* Set the controller in Master transmit mode and clear the FIFO. */
 432         ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 433         ctrl_reg &= ~CDNS_I2C_CR_RW;
 434         ctrl_reg |= CDNS_I2C_CR_CLR_FIFO;
 435
 436         /*
 437          * Check for the message size against FIFO depth and set the
 438          * 'hold bus' bit if it is greater than FIFO depth.
 439          */
 440         if ((id->send_count > CDNS_I2C_FIFO_DEPTH) || id->bus_hold_flag)
 441                 ctrl_reg |= CDNS_I2C_CR_HOLD;
 442         else
 443                 ctrl_reg = ctrl_reg & ~CDNS_I2C_CR_HOLD;
 444
 445         cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 446
 447         /* Clear the interrupts in interrupt status register. */
 448         isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 449         cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 450
 451         /*
 452          * Calculate the space available in FIFO. Check the message length
 453          * against the space available, and fill the FIFO accordingly.
 454          * Enable the interrupts.
 455          */
 456         avail_bytes = CDNS_I2C_FIFO_DEPTH -
 457                                 cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
 458
 459         if (id->send_count > avail_bytes)
 460                 bytes_to_send = avail_bytes;
 461         else
 462                 bytes_to_send = id->send_count;
 463
 464         while (bytes_to_send--) {
 465                 cdns_i2c_writereg((*(id->p_send_buf)++), CDNS_I2C_DATA_OFFSET);
 466                 id->send_count--;
 467         }
 468
 469         /*
 470          * Clear the bus hold flag if there is no more data
 471          * and if it is the last message.
 472          */
 473         if (!id->bus_hold_flag && !id->send_count)
 474                 cdns_i2c_clear_bus_hold(id);
 475         /* Set the slave address in address register - triggers operation. */
 476         cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
 477                                                 CDNS_I2C_ADDR_OFFSET);
 478
 479         cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET);
 480 }
 481
 482 /**
 483  * cdns_i2c_master_reset - Reset the interface
 484  * @adap:       pointer to the i2c adapter driver instance
 485  *
 486  * This function cleanup the fifos, clear the hold bit and status
 487  * and disable the interrupts.
 488  */
 489 static void cdns_i2c_master_reset(struct i2c_adapter *adap)
 490 {
 491         struct cdns_i2c *id = adap->algo_data;
 492         u32 regval;
 493
 494         /* Disable the interrupts */
 495         cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);
 496         /* Clear the hold bit and fifos */
 497         regval = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 498         regval &= ~CDNS_I2C_CR_HOLD;
 499         regval |= CDNS_I2C_CR_CLR_FIFO;
 500         cdns_i2c_writereg(regval, CDNS_I2C_CR_OFFSET);
 501         /* Update the transfercount register to zero */
 502         cdns_i2c_writereg(0, CDNS_I2C_XFER_SIZE_OFFSET);
 503         /* Clear the interupt status register */
 504         regval = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 505         cdns_i2c_writereg(regval, CDNS_I2C_ISR_OFFSET);
 506         /* Clear the status register */
 507         regval = cdns_i2c_readreg(CDNS_I2C_SR_OFFSET);
 508         cdns_i2c_writereg(regval, CDNS_I2C_SR_OFFSET);
 509 }
 510
 511 static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 512                 struct i2c_adapter *adap)
 513 {
 514         unsigned long time_left;
 515         u32 reg;
 516
 517         id->p_msg = msg;
 518         id->err_status = 0;
 519         reinit_completion(&id->xfer_done);
 520
 521         /* Check for the TEN Bit mode on each msg */
 522         reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 523         if (msg->flags & I2C_M_TEN) {
 524                 if (reg & CDNS_I2C_CR_NEA)
 525                         cdns_i2c_writereg(reg & ~CDNS_I2C_CR_NEA,
 526                                         CDNS_I2C_CR_OFFSET);
 527         } else {
 528                 if (!(reg & CDNS_I2C_CR_NEA))
 529                         cdns_i2c_writereg(reg | CDNS_I2C_CR_NEA,
 530                                         CDNS_I2C_CR_OFFSET);
 531         }
 532
 533         /* Check for the R/W flag on each msg */
 534         if (msg->flags & I2C_M_RD)
 535                 cdns_i2c_mrecv(id);
 536         else
 537                 cdns_i2c_msend(id);
 538
 539         /* Wait for the signal of completion */
 540         time_left = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
 541         if (time_left == 0) {
 542                 cdns_i2c_master_reset(adap);
 543                 dev_err(id->adap.dev.parent,
 544                                 "timeout waiting on completion\n");
 545                 return -ETIMEDOUT;
 546         }
 547
 548         cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK,
 549                           CDNS_I2C_IDR_OFFSET);
 550
 551         /* If it is bus arbitration error, try again */
 552         if (id->err_status & CDNS_I2C_IXR_ARB_LOST)
 553                 return -EAGAIN;
 554
 555         return 0;
 556 }
 557
 558 /**
 559  * cdns_i2c_master_xfer - The main i2c transfer function
 560  * @adap:       pointer to the i2c adapter driver instance
 561  * @msgs:       pointer to the i2c message structure
 562  * @num:        the number of messages to transfer
 563  *
 564  * Initiates the send/recv activity based on the transfer message received.
 565  *
 566  * Return: number of msgs processed on success, negative error otherwise
 567  */
 568 static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 569                                 int num)
 570 {
 571         int ret, count;
 572         u32 reg;
 573         struct cdns_i2c *id = adap->algo_data;
 574         bool hold_quirk;
 575
 576         ret = pm_runtime_get_sync(id->dev);
 577         if (ret < 0)
 578                 return ret;
 579         /* Check if the bus is free */
 580         if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) {
 581                 ret = -EAGAIN;
 582                 goto out;
 583         }
 584
 585         hold_quirk = !!(id->quirks & CDNS_I2C_BROKEN_HOLD_BIT);
 586         /*
 587          * Set the flag to one when multiple messages are to be
 588          * processed with a repeated start.
 589          */
 590         if (num > 1) {
 591                 /*
 592                  * This controller does not give completion interrupt after a
 593                  * master receive message if HOLD bit is set (repeated start),
 594                  * resulting in SW timeout. Hence, if a receive message is
 595                  * followed by any other message, an error is returned
 596                  * indicating that this sequence is not supported.
 597                  */
 598                 for (count = 0; (count < num - 1 && hold_quirk); count++) {
 599                         if (msgs[count].flags & I2C_M_RD) {
 600                                 dev_warn(adap->dev.parent,
 601                                          "Can't do repeated start after a receive message\n");
 602                                 ret = -EOPNOTSUPP;
 603                                 goto out;
 604                         }
 605                 }
 606                 id->bus_hold_flag = 1;
 607                 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 608                 reg |= CDNS_I2C_CR_HOLD;
 609                 cdns_i2c_writereg(reg, CDNS_I2C_CR_OFFSET);
 610         } else {
 611                 id->bus_hold_flag = 0;
 612         }
 613
 614         /* Process the msg one by one */
 615         for (count = 0; count < num; count++, msgs++) {
 616                 if (count == (num - 1))
 617                         id->bus_hold_flag = 0;
 618
 619                 ret = cdns_i2c_process_msg(id, msgs, adap);
 620                 if (ret)
 621                         goto out;
 622
 623                 /* Report the other error interrupts to application */
 624                 if (id->err_status) {
 625                         cdns_i2c_master_reset(adap);
 626
 627                         if (id->err_status & CDNS_I2C_IXR_NACK) {
 628                                 ret = -ENXIO;
 629                                 goto out;
 630                         }
 631                         ret = -EIO;
 632                         goto out;
 633                 }
 634         }
 635
 636         ret = num;
 637 out:
 638         pm_runtime_mark_last_busy(id->dev);
 639         pm_runtime_put_autosuspend(id->dev);
 640         return ret;
 641 }
 642
 643 /**
 644  * cdns_i2c_func - Returns the supported features of the I2C driver
 645  * @adap:       pointer to the i2c adapter structure
 646  *
 647  * Return: 32 bit value, each bit corresponding to a feature
 648  */
 649 static u32 cdns_i2c_func(struct i2c_adapter *adap)
 650 {
 651         return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
 652                 (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
 653                 I2C_FUNC_SMBUS_BLOCK_DATA;
 654 }
 655
 656 static const struct i2c_algorithm cdns_i2c_algo = {
 657         .master_xfer    = cdns_i2c_master_xfer,
 658         .functionality  = cdns_i2c_func,
 659 };
 660
 661 /**
 662  * cdns_i2c_calc_divs - Calculate clock dividers
 663  * @f:          I2C clock frequency
 664  * @input_clk:  Input clock frequency
 665  * @a:          First divider (return value)
 666  * @b:          Second divider (return value)
 667  *
 668  * f is used as input and output variable. As input it is used as target I2C
 669  * frequency. On function exit f holds the actually resulting I2C frequency.
 670  *
 671  * Return: 0 on success, negative errno otherwise.
 672  */
 673 static int cdns_i2c_calc_divs(unsigned long *f, unsigned long input_clk,
 674                 unsigned int *a, unsigned int *b)
 675 {
 676         unsigned long fscl = *f, best_fscl = *f, actual_fscl, temp;
 677         unsigned int div_a, div_b, calc_div_a = 0, calc_div_b = 0;
 678         unsigned int last_error, current_error;
 679
 680         /* calculate (divisor_a+1) x (divisor_b+1) */
 681         temp = input_clk / (22 * fscl);
 682
 683         /*
 684          * If the calculated value is negative or 0, the fscl input is out of
 685          * range. Return error.
 686          */
 687         if (!temp || (temp > (CDNS_I2C_DIVA_MAX * CDNS_I2C_DIVB_MAX)))
 688                 return -EINVAL;
 689
 690         last_error = -1;
 691         for (div_a = 0; div_a < CDNS_I2C_DIVA_MAX; div_a++) {
 692                 div_b = DIV_ROUND_UP(input_clk, 22 * fscl * (div_a + 1));
 693
 694                 if ((div_b < 1) || (div_b > CDNS_I2C_DIVB_MAX))
 695                         continue;
 696                 div_b--;
 697
 698                 actual_fscl = input_clk / (22 * (div_a + 1) * (div_b + 1));
 699
 700                 if (actual_fscl > fscl)
 701                         continue;
 702
 703                 current_error = ((actual_fscl > fscl) ? (actual_fscl - fscl) :
 704                                                         (fscl - actual_fscl));
 705
 706                 if (last_error > current_error) {
 707                         calc_div_a = div_a;
 708                         calc_div_b = div_b;
 709                         best_fscl = actual_fscl;
 710                         last_error = current_error;
 711                 }
 712         }
 713
 714         *a = calc_div_a;
 715         *b = calc_div_b;
 716         *f = best_fscl;
 717
 718         return 0;
 719 }
 720
 721 /**
 722  * cdns_i2c_setclk - This function sets the serial clock rate for the I2C device
 723  * @clk_in:     I2C clock input frequency in Hz
 724  * @id:         Pointer to the I2C device structure
 725  *
 726  * The device must be idle rather than busy transferring data before setting
 727  * these device options.
 728  * The data rate is set by values in the control register.
 729  * The formula for determining the correct register values is
 730  *      Fscl = Fpclk/(22 x (divisor_a+1) x (divisor_b+1))
 731  * See the hardware data sheet for a full explanation of setting the serial
 732  * clock rate. The clock can not be faster than the input clock divide by 22.
 733  * The two most common clock rates are 100KHz and 400KHz.
 734  *
 735  * Return: 0 on success, negative error otherwise
 736  */
 737 static int cdns_i2c_setclk(unsigned long clk_in, struct cdns_i2c *id)
 738 {
 739         unsigned int div_a, div_b;
 740         unsigned int ctrl_reg;
 741         int ret = 0;
 742         unsigned long fscl = id->i2c_clk;
 743
 744         ret = cdns_i2c_calc_divs(&fscl, clk_in, &div_a, &div_b);
 745         if (ret)
 746                 return ret;
 747
 748         ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 749         ctrl_reg &= ~(CDNS_I2C_CR_DIVA_MASK | CDNS_I2C_CR_DIVB_MASK);
 750         ctrl_reg |= ((div_a << CDNS_I2C_CR_DIVA_SHIFT) |
 751                         (div_b << CDNS_I2C_CR_DIVB_SHIFT));
 752         cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 753
 754         return 0;
 755 }
 756
 757 /**
 758  * cdns_i2c_clk_notifier_cb - Clock rate change callback
 759  * @nb:         Pointer to notifier block
 760  * @event:      Notification reason
 761  * @data:       Pointer to notification data object
 762  *
 763  * This function is called when the cdns_i2c input clock frequency changes.
 764  * The callback checks whether a valid bus frequency can be generated after the
 765  * change. If so, the change is acknowledged, otherwise the change is aborted.
 766  * New dividers are written to the HW in the pre- or post change notification
 767  * depending on the scaling direction.
 768  *
 769  * Return:      NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK
 770  *              to acknowledge the change, NOTIFY_DONE if the notification is
 771  *              considered irrelevant.
 772  */
 773 static int cdns_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
 774                 event, void *data)
 775 {
 776         struct clk_notifier_data *ndata = data;
 777         struct cdns_i2c *id = to_cdns_i2c(nb);
 778
 779         if (pm_runtime_suspended(id->dev))
 780                 return NOTIFY_OK;
 781
 782         switch (event) {
 783         case PRE_RATE_CHANGE:
 784         {
 785                 unsigned long input_clk = ndata->new_rate;
 786                 unsigned long fscl = id->i2c_clk;
 787                 unsigned int div_a, div_b;
 788                 int ret;
 789
 790                 ret = cdns_i2c_calc_divs(&fscl, input_clk, &div_a, &div_b);
 791                 if (ret) {
 792                         dev_warn(id->adap.dev.parent,
 793                                         "clock rate change rejected\n");
 794                         return NOTIFY_STOP;
 795                 }
 796
 797                 /* scale up */
 798                 if (ndata->new_rate > ndata->old_rate)
 799                         cdns_i2c_setclk(ndata->new_rate, id);
 800
 801                 return NOTIFY_OK;
 802         }
 803         case POST_RATE_CHANGE:
 804                 id->input_clk = ndata->new_rate;
 805                 /* scale down */
 806                 if (ndata->new_rate < ndata->old_rate)
 807                         cdns_i2c_setclk(ndata->new_rate, id);
 808                 return NOTIFY_OK;
 809         case ABORT_RATE_CHANGE:
 810                 /* scale up */
 811                 if (ndata->new_rate > ndata->old_rate)
 812                         cdns_i2c_setclk(ndata->old_rate, id);
 813                 return NOTIFY_OK;
 814         default:
 815                 return NOTIFY_DONE;
 816         }
 817 }
 818
 819 /**
 820  * cdns_i2c_runtime_suspend -  Runtime suspend method for the driver
 821  * @dev:        Address of the platform_device structure
 822  *
 823  * Put the driver into low power mode.
 824  *
 825  * Return: 0 always
 826  */
 827 static int __maybe_unused cdns_i2c_runtime_suspend(struct device *dev)
 828 {
 829         struct cdns_i2c *xi2c = dev_get_drvdata(dev);
 830
 831         clk_disable(xi2c->clk);
 832
 833         return 0;
 834 }
 835
 836 /**
 837  * cdns_i2c_runtime_resume - Runtime resume
 838  * @dev:        Address of the platform_device structure
 839  *
 840  * Runtime resume callback.
 841  *
 842  * Return: 0 on success and error value on error
 843  */
 844 static int __maybe_unused cdns_i2c_runtime_resume(struct device *dev)
 845 {
 846         struct cdns_i2c *xi2c = dev_get_drvdata(dev);
 847         int ret;
 848
 849         ret = clk_enable(xi2c->clk);
 850         if (ret) {
 851                 dev_err(dev, "Cannot enable clock.\n");
 852                 return ret;
 853         }
 854
 855         return 0;
 856 }
 857
 858 static const struct dev_pm_ops cdns_i2c_dev_pm_ops = {
 859         SET_RUNTIME_PM_OPS(cdns_i2c_runtime_suspend,
 860                            cdns_i2c_runtime_resume, NULL)
 861 };
 862
 863 static const struct cdns_platform_data r1p10_i2c_def = {
 864         .quirks = CDNS_I2C_BROKEN_HOLD_BIT,
 865 };
 866
 867 static const struct of_device_id cdns_i2c_of_match[] = {
 868         { .compatible = "cdns,i2c-r1p10", .data = &r1p10_i2c_def },
 869         { .compatible = "cdns,i2c-r1p14",},
 870         { /* end of table */ }
 871 };
 872 MODULE_DEVICE_TABLE(of, cdns_i2c_of_match);
 873
 874 /**
 875  * cdns_i2c_probe - Platform registration call
 876  * @pdev:       Handle to the platform device structure
 877  *
 878  * This function does all the memory allocation and registration for the i2c
 879  * device. User can modify the address mode to 10 bit address mode using the
 880  * ioctl call with option I2C_TENBIT.
 881  *
 882  * Return: 0 on success, negative error otherwise
 883  */
 884 static int cdns_i2c_probe(struct platform_device *pdev)
 885 {
 886         struct resource *r_mem;
 887         struct cdns_i2c *id;
 888         int ret;
 889         const struct of_device_id *match;
 890
 891         id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL);
 892         if (!id)
 893                 return -ENOMEM;
 894
 895         id->dev = &pdev->dev;
 896         platform_set_drvdata(pdev, id);
 897
 898         match = of_match_node(cdns_i2c_of_match, pdev->dev.of_node);
 899         if (match && match->data) {
 900                 const struct cdns_platform_data *data = match->data;
 901                 id->quirks = data->quirks;
 902         }
 903
 904         r_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 905         id->membase = devm_ioremap_resource(&pdev->dev, r_mem);
 906         if (IS_ERR(id->membase))
 907                 return PTR_ERR(id->membase);
 908
 909         id->irq = platform_get_irq(pdev, 0);
 910
 911         id->adap.owner = THIS_MODULE;
 912         id->adap.dev.of_node = pdev->dev.of_node;
 913         id->adap.algo = &cdns_i2c_algo;
 914         id->adap.timeout = CDNS_I2C_TIMEOUT;
 915         id->adap.retries = 3;           /* Default retry value. */
 916         id->adap.algo_data = id;
 917         id->adap.dev.parent = &pdev->dev;
 918         init_completion(&id->xfer_done);
 919         snprintf(id->adap.name, sizeof(id->adap.name),
 920                  "Cadence I2C at %08lx", (unsigned long)r_mem->start);
 921
 922         id->clk = devm_clk_get(&pdev->dev, NULL);
 923         if (IS_ERR(id->clk)) {
 924                 dev_err(&pdev->dev, "input clock not found.\n");
 925                 return PTR_ERR(id->clk);
 926         }
 927         ret = clk_prepare_enable(id->clk);
 928         if (ret)
 929                 dev_err(&pdev->dev, "Unable to enable clock.\n");
 930
 931         pm_runtime_enable(id->dev);
 932         pm_runtime_set_autosuspend_delay(id->dev, CNDS_I2C_PM_TIMEOUT);
 933         pm_runtime_use_autosuspend(id->dev);
 934         pm_runtime_set_active(id->dev);
 935
 936         id->clk_rate_change_nb.notifier_call = cdns_i2c_clk_notifier_cb;
 937         if (clk_notifier_register(id->clk, &id->clk_rate_change_nb))
 938                 dev_warn(&pdev->dev, "Unable to register clock notifier.\n");
 939         id->input_clk = clk_get_rate(id->clk);
 940
 941         ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 942                         &id->i2c_clk);
 943         if (ret || (id->i2c_clk > CDNS_I2C_SPEED_MAX))
 944                 id->i2c_clk = CDNS_I2C_SPEED_DEFAULT;
 945
 946         cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS,
 947                           CDNS_I2C_CR_OFFSET);
 948
 949         ret = cdns_i2c_setclk(id->input_clk, id);
 950         if (ret) {
 951                 dev_err(&pdev->dev, "invalid SCL clock: %u Hz\n", id->i2c_clk);
 952                 ret = -EINVAL;
 953                 goto err_clk_dis;
 954         }
 955
 956         ret = devm_request_irq(&pdev->dev, id->irq, cdns_i2c_isr, 0,
 957                                  DRIVER_NAME, id);
 958         if (ret) {
 959                 dev_err(&pdev->dev, "cannot get irq %d\n", id->irq);
 960                 goto err_clk_dis;
 961         }
 962
 963         /*
 964          * Cadence I2C controller has a bug wherein it generates
 965          * invalid read transaction after HW timeout in master receiver mode.
 966          * HW timeout is not used by this driver and the interrupt is disabled.
 967          * But the feature itself cannot be disabled. Hence maximum value
 968          * is written to this register to reduce the chances of error.
 969          */
 970         cdns_i2c_writereg(CDNS_I2C_TIMEOUT_MAX, CDNS_I2C_TIME_OUT_OFFSET);
 971
 972         ret = i2c_add_adapter(&id->adap);
 973         if (ret < 0)
 974                 goto err_clk_dis;
 975
 976         dev_info(&pdev->dev, "%u kHz mmio %08lx irq %d\n",
 977                  id->i2c_clk / 1000, (unsigned long)r_mem->start, id->irq);
 978
 979         return 0;
 980
 981 err_clk_dis:
 982         clk_disable_unprepare(id->clk);
 983         pm_runtime_set_suspended(&pdev->dev);
 984         pm_runtime_disable(&pdev->dev);
 985         return ret;
 986 }
 987
 988 /**
 989  * cdns_i2c_remove - Unregister the device after releasing the resources
 990  * @pdev:       Handle to the platform device structure
 991  *
 992  * This function frees all the resources allocated to the device.
 993  *
 994  * Return: 0 always
 995  */
 996 static int cdns_i2c_remove(struct platform_device *pdev)
 997 {
 998         struct cdns_i2c *id = platform_get_drvdata(pdev);
 999
1000         i2c_del_adapter(&id->adap);
1001         clk_notifier_unregister(id->clk, &id->clk_rate_change_nb);
1002         clk_disable_unprepare(id->clk);
1003         pm_runtime_disable(&pdev->dev);
1004
1005         return 0;
1006 }
1007
1008 static struct platform_driver cdns_i2c_drv = {
1009         .driver = {
1010                 .name  = DRIVER_NAME,
1011                 .of_match_table = cdns_i2c_of_match,
1012                 .pm = &cdns_i2c_dev_pm_ops,
1013         },
1014         .probe  = cdns_i2c_probe,
1015         .remove = cdns_i2c_remove,
1016 };
1017
1018 module_platform_driver(cdns_i2c_drv);
1019
1020 MODULE_AUTHOR("Xilinx Inc.");
1021 MODULE_DESCRIPTION("Cadence I2C bus driver");
1022 MODULE_LICENSE("GPL");