drivers/i2c/busses/i2c-aspeed.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Aspeed 24XX/25XX I2C Controller.
   4  *
   5  *  Copyright (C) 2012-2017 ASPEED Technology Inc.
   6  *  Copyright 2017 IBM Corporation
   7  *  Copyright 2017 Google, Inc.
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/completion.h>
  12 #include <linux/err.h>
  13 #include <linux/errno.h>
  14 #include <linux/i2c.h>
  15 #include <linux/init.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/io.h>
  18 #include <linux/irq.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/of_address.h>
  22 #include <linux/of_irq.h>
  23 #include <linux/of_platform.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/reset.h>
  26 #include <linux/slab.h>
  27
  28 /* I2C Register */
  29 #define ASPEED_I2C_FUN_CTRL_REG                         0x00
  30 #define ASPEED_I2C_AC_TIMING_REG1                       0x04
  31 #define ASPEED_I2C_AC_TIMING_REG2                       0x08
  32 #define ASPEED_I2C_INTR_CTRL_REG                        0x0c
  33 #define ASPEED_I2C_INTR_STS_REG                         0x10
  34 #define ASPEED_I2C_CMD_REG                              0x14
  35 #define ASPEED_I2C_DEV_ADDR_REG                         0x18
  36 #define ASPEED_I2C_BYTE_BUF_REG                         0x20
  37
  38 /* Global Register Definition */
  39 /* 0x00 : I2C Interrupt Status Register  */
  40 /* 0x08 : I2C Interrupt Target Assignment  */
  41
  42 /* Device Register Definition */
  43 /* 0x00 : I2CD Function Control Register  */
  44 #define ASPEED_I2CD_MULTI_MASTER_DIS                    BIT(15)
  45 #define ASPEED_I2CD_SDA_DRIVE_1T_EN                     BIT(8)
  46 #define ASPEED_I2CD_M_SDA_DRIVE_1T_EN                   BIT(7)
  47 #define ASPEED_I2CD_M_HIGH_SPEED_EN                     BIT(6)
  48 #define ASPEED_I2CD_SLAVE_EN                            BIT(1)
  49 #define ASPEED_I2CD_MASTER_EN                           BIT(0)
  50
  51 /* 0x04 : I2CD Clock and AC Timing Control Register #1 */
  52 #define ASPEED_I2CD_TIME_TBUF_MASK                      GENMASK(31, 28)
  53 #define ASPEED_I2CD_TIME_THDSTA_MASK                    GENMASK(27, 24)
  54 #define ASPEED_I2CD_TIME_TACST_MASK                     GENMASK(23, 20)
  55 #define ASPEED_I2CD_TIME_SCL_HIGH_SHIFT                 16
  56 #define ASPEED_I2CD_TIME_SCL_HIGH_MASK                  GENMASK(19, 16)
  57 #define ASPEED_I2CD_TIME_SCL_LOW_SHIFT                  12
  58 #define ASPEED_I2CD_TIME_SCL_LOW_MASK                   GENMASK(15, 12)
  59 #define ASPEED_I2CD_TIME_BASE_DIVISOR_MASK              GENMASK(3, 0)
  60 #define ASPEED_I2CD_TIME_SCL_REG_MAX                    GENMASK(3, 0)
  61 /* 0x08 : I2CD Clock and AC Timing Control Register #2 */
  62 #define ASPEED_NO_TIMEOUT_CTRL                          0
  63
  64 /* 0x0c : I2CD Interrupt Control Register &
  65  * 0x10 : I2CD Interrupt Status Register
  66  *
  67  * These share bit definitions, so use the same values for the enable &
  68  * status bits.
  69  */
  70 #define ASPEED_I2CD_INTR_RECV_MASK                      0xf000ffff
  71 #define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT                 BIT(14)
  72 #define ASPEED_I2CD_INTR_BUS_RECOVER_DONE               BIT(13)
  73 #define ASPEED_I2CD_INTR_SLAVE_MATCH                    BIT(7)
  74 #define ASPEED_I2CD_INTR_SCL_TIMEOUT                    BIT(6)
  75 #define ASPEED_I2CD_INTR_ABNORMAL                       BIT(5)
  76 #define ASPEED_I2CD_INTR_NORMAL_STOP                    BIT(4)
  77 #define ASPEED_I2CD_INTR_ARBIT_LOSS                     BIT(3)
  78 #define ASPEED_I2CD_INTR_RX_DONE                        BIT(2)
  79 #define ASPEED_I2CD_INTR_TX_NAK                         BIT(1)
  80 #define ASPEED_I2CD_INTR_TX_ACK                         BIT(0)
  81 #define ASPEED_I2CD_INTR_MASTER_ERRORS                                         \
  82                 (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |                             \
  83                  ASPEED_I2CD_INTR_SCL_TIMEOUT |                                \
  84                  ASPEED_I2CD_INTR_ABNORMAL |                                   \
  85                  ASPEED_I2CD_INTR_ARBIT_LOSS)
  86 #define ASPEED_I2CD_INTR_ALL                                                   \
  87                 (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |                             \
  88                  ASPEED_I2CD_INTR_BUS_RECOVER_DONE |                           \
  89                  ASPEED_I2CD_INTR_SCL_TIMEOUT |                                \
  90                  ASPEED_I2CD_INTR_ABNORMAL |                                   \
  91                  ASPEED_I2CD_INTR_NORMAL_STOP |                                \
  92                  ASPEED_I2CD_INTR_ARBIT_LOSS |                                 \
  93                  ASPEED_I2CD_INTR_RX_DONE |                                    \
  94                  ASPEED_I2CD_INTR_TX_NAK |                                     \
  95                  ASPEED_I2CD_INTR_TX_ACK)
  96
  97 /* 0x14 : I2CD Command/Status Register   */
  98 #define ASPEED_I2CD_SCL_LINE_STS                        BIT(18)
  99 #define ASPEED_I2CD_SDA_LINE_STS                        BIT(17)
 100 #define ASPEED_I2CD_BUS_BUSY_STS                        BIT(16)
 101 #define ASPEED_I2CD_BUS_RECOVER_CMD                     BIT(11)
 102
 103 /* Command Bit */
 104 #define ASPEED_I2CD_M_STOP_CMD                          BIT(5)
 105 #define ASPEED_I2CD_M_S_RX_CMD_LAST                     BIT(4)
 106 #define ASPEED_I2CD_M_RX_CMD                            BIT(3)
 107 #define ASPEED_I2CD_S_TX_CMD                            BIT(2)
 108 #define ASPEED_I2CD_M_TX_CMD                            BIT(1)
 109 #define ASPEED_I2CD_M_START_CMD                         BIT(0)
 110 #define ASPEED_I2CD_MASTER_CMDS_MASK                                           \
 111                 (ASPEED_I2CD_M_STOP_CMD |                                      \
 112                  ASPEED_I2CD_M_S_RX_CMD_LAST |                                 \
 113                  ASPEED_I2CD_M_RX_CMD |                                        \
 114                  ASPEED_I2CD_M_TX_CMD |                                        \
 115                  ASPEED_I2CD_M_START_CMD)
 116
 117 /* 0x18 : I2CD Slave Device Address Register   */
 118 #define ASPEED_I2CD_DEV_ADDR_MASK                       GENMASK(6, 0)
 119
 120 enum aspeed_i2c_master_state {
 121         ASPEED_I2C_MASTER_INACTIVE,
 122         ASPEED_I2C_MASTER_PENDING,
 123         ASPEED_I2C_MASTER_START,
 124         ASPEED_I2C_MASTER_TX_FIRST,
 125         ASPEED_I2C_MASTER_TX,
 126         ASPEED_I2C_MASTER_RX_FIRST,
 127         ASPEED_I2C_MASTER_RX,
 128         ASPEED_I2C_MASTER_STOP,
 129 };
 130
 131 enum aspeed_i2c_slave_state {
 132         ASPEED_I2C_SLAVE_INACTIVE,
 133         ASPEED_I2C_SLAVE_START,
 134         ASPEED_I2C_SLAVE_READ_REQUESTED,
 135         ASPEED_I2C_SLAVE_READ_PROCESSED,
 136         ASPEED_I2C_SLAVE_WRITE_REQUESTED,
 137         ASPEED_I2C_SLAVE_WRITE_RECEIVED,
 138         ASPEED_I2C_SLAVE_STOP,
 139 };
 140
 141 struct aspeed_i2c_bus {
 142         struct i2c_adapter              adap;
 143         struct device                   *dev;
 144         void __iomem                    *base;
 145         struct reset_control            *rst;
 146         /* Synchronizes I/O mem access to base. */
 147         spinlock_t                      lock;
 148         struct completion               cmd_complete;
 149         u32                             (*get_clk_reg_val)(struct device *dev,
 150                                                            u32 divisor);
 151         unsigned long                   parent_clk_frequency;
 152         u32                             bus_frequency;
 153         /* Transaction state. */
 154         enum aspeed_i2c_master_state    master_state;
 155         struct i2c_msg                  *msgs;
 156         size_t                          buf_index;
 157         size_t                          msgs_index;
 158         size_t                          msgs_count;
 159         bool                            send_stop;
 160         int                             cmd_err;
 161         /* Protected only by i2c_lock_bus */
 162         int                             master_xfer_result;
 163         /* Multi-master */
 164         bool                            multi_master;
 165 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 166         struct i2c_client               *slave;
 167         enum aspeed_i2c_slave_state     slave_state;
 168 #endif /* CONFIG_I2C_SLAVE */
 169 };
 170
 171 static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus);
 172
 173 static int aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
 174 {
 175         unsigned long time_left, flags;
 176         int ret = 0;
 177         u32 command;
 178
 179         spin_lock_irqsave(&bus->lock, flags);
 180         command = readl(bus->base + ASPEED_I2C_CMD_REG);
 181
 182         if (command & ASPEED_I2CD_SDA_LINE_STS) {
 183                 /* Bus is idle: no recovery needed. */
 184                 if (command & ASPEED_I2CD_SCL_LINE_STS)
 185                         goto out;
 186                 dev_dbg(bus->dev, "SCL hung (state %x), attempting recovery\n",
 187                         command);
 188
 189                 reinit_completion(&bus->cmd_complete);
 190                 writel(ASPEED_I2CD_M_STOP_CMD, bus->base + ASPEED_I2C_CMD_REG);
 191                 spin_unlock_irqrestore(&bus->lock, flags);
 192
 193                 time_left = wait_for_completion_timeout(
 194                                 &bus->cmd_complete, bus->adap.timeout);
 195
 196                 spin_lock_irqsave(&bus->lock, flags);
 197                 if (time_left == 0)
 198                         goto reset_out;
 199                 else if (bus->cmd_err)
 200                         goto reset_out;
 201                 /* Recovery failed. */
 202                 else if (!(readl(bus->base + ASPEED_I2C_CMD_REG) &
 203                            ASPEED_I2CD_SCL_LINE_STS))
 204                         goto reset_out;
 205         /* Bus error. */
 206         } else {
 207                 dev_dbg(bus->dev, "SDA hung (state %x), attempting recovery\n",
 208                         command);
 209
 210                 reinit_completion(&bus->cmd_complete);
 211                 /* Writes 1 to 8 SCL clock cycles until SDA is released. */
 212                 writel(ASPEED_I2CD_BUS_RECOVER_CMD,
 213                        bus->base + ASPEED_I2C_CMD_REG);
 214                 spin_unlock_irqrestore(&bus->lock, flags);
 215
 216                 time_left = wait_for_completion_timeout(
 217                                 &bus->cmd_complete, bus->adap.timeout);
 218
 219                 spin_lock_irqsave(&bus->lock, flags);
 220                 if (time_left == 0)
 221                         goto reset_out;
 222                 else if (bus->cmd_err)
 223                         goto reset_out;
 224                 /* Recovery failed. */
 225                 else if (!(readl(bus->base + ASPEED_I2C_CMD_REG) &
 226                            ASPEED_I2CD_SDA_LINE_STS))
 227                         goto reset_out;
 228         }
 229
 230 out:
 231         spin_unlock_irqrestore(&bus->lock, flags);
 232
 233         return ret;
 234
 235 reset_out:
 236         spin_unlock_irqrestore(&bus->lock, flags);
 237
 238         return aspeed_i2c_reset(bus);
 239 }
 240
 241 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 242 static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 243 {
 244         u32 command, irq_handled = 0;
 245         struct i2c_client *slave = bus->slave;
 246         u8 value;
 247         int ret;
 248
 249         if (!slave)
 250                 return 0;
 251
 252         command = readl(bus->base + ASPEED_I2C_CMD_REG);
 253
 254         /* Slave was requested, restart state machine. */
 255         if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
 256                 irq_handled |= ASPEED_I2CD_INTR_SLAVE_MATCH;
 257                 bus->slave_state = ASPEED_I2C_SLAVE_START;
 258         }
 259
 260         /* Slave is not currently active, irq was for someone else. */
 261         if (bus->slave_state == ASPEED_I2C_SLAVE_INACTIVE)
 262                 return irq_handled;
 263
 264         dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
 265                 irq_status, command);
 266
 267         /* Slave was sent something. */
 268         if (irq_status & ASPEED_I2CD_INTR_RX_DONE) {
 269                 value = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
 270                 /* Handle address frame. */
 271                 if (bus->slave_state == ASPEED_I2C_SLAVE_START) {
 272                         if (value & 0x1)
 273                                 bus->slave_state =
 274                                                 ASPEED_I2C_SLAVE_READ_REQUESTED;
 275                         else
 276                                 bus->slave_state =
 277                                                 ASPEED_I2C_SLAVE_WRITE_REQUESTED;
 278                 }
 279                 irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
 280         }
 281
 282         /* Slave was asked to stop. */
 283         if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
 284                 irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
 285                 bus->slave_state = ASPEED_I2C_SLAVE_STOP;
 286         }
 287         if (irq_status & ASPEED_I2CD_INTR_TX_NAK &&
 288             bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) {
 289                 irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
 290                 bus->slave_state = ASPEED_I2C_SLAVE_STOP;
 291         }
 292
 293         switch (bus->slave_state) {
 294         case ASPEED_I2C_SLAVE_READ_REQUESTED:
 295                 if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_ACK))
 296                         dev_err(bus->dev, "Unexpected ACK on read request.\n");
 297                 bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
 298                 i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
 299                 writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
 300                 writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
 301                 break;
 302         case ASPEED_I2C_SLAVE_READ_PROCESSED:
 303                 if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
 304                         dev_err(bus->dev,
 305                                 "Expected ACK after processed read.\n");
 306                         break;
 307                 }
 308                 irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
 309                 i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
 310                 writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
 311                 writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
 312                 break;
 313         case ASPEED_I2C_SLAVE_WRITE_REQUESTED:
 314                 bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
 315                 ret = i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
 316                 /*
 317                  * Slave ACK's on this address phase already but as the backend driver
 318                  * returns an errno, the bus driver should nack the next incoming byte.
 319                  */
 320                 if (ret < 0)
 321                         writel(ASPEED_I2CD_M_S_RX_CMD_LAST, bus->base + ASPEED_I2C_CMD_REG);
 322                 break;
 323         case ASPEED_I2C_SLAVE_WRITE_RECEIVED:
 324                 i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
 325                 break;
 326         case ASPEED_I2C_SLAVE_STOP:
 327                 i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
 328                 bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
 329                 break;
 330         case ASPEED_I2C_SLAVE_START:
 331                 /* Slave was just started. Waiting for the next event. */;
 332                 break;
 333         default:
 334                 dev_err(bus->dev, "unknown slave_state: %d\n",
 335                         bus->slave_state);
 336                 bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
 337                 break;
 338         }
 339
 340         return irq_handled;
 341 }
 342 #endif /* CONFIG_I2C_SLAVE */
 343
 344 /* precondition: bus.lock has been acquired. */
 345 static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
 346 {
 347         u32 command = ASPEED_I2CD_M_START_CMD | ASPEED_I2CD_M_TX_CMD;
 348         struct i2c_msg *msg = &bus->msgs[bus->msgs_index];
 349         u8 slave_addr = i2c_8bit_addr_from_msg(msg);
 350
 351 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 352         /*
 353          * If it's requested in the middle of a slave session, set the master
 354          * state to 'pending' then H/W will continue handling this master
 355          * command when the bus comes back to the idle state.
 356          */
 357         if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE) {
 358                 bus->master_state = ASPEED_I2C_MASTER_PENDING;
 359                 return;
 360         }
 361 #endif /* CONFIG_I2C_SLAVE */
 362
 363         bus->master_state = ASPEED_I2C_MASTER_START;
 364         bus->buf_index = 0;
 365
 366         if (msg->flags & I2C_M_RD) {
 367                 command |= ASPEED_I2CD_M_RX_CMD;
 368                 /* Need to let the hardware know to NACK after RX. */
 369                 if (msg->len == 1 && !(msg->flags & I2C_M_RECV_LEN))
 370                         command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
 371         }
 372
 373         writel(slave_addr, bus->base + ASPEED_I2C_BYTE_BUF_REG);
 374         writel(command, bus->base + ASPEED_I2C_CMD_REG);
 375 }
 376
 377 /* precondition: bus.lock has been acquired. */
 378 static void aspeed_i2c_do_stop(struct aspeed_i2c_bus *bus)
 379 {
 380         bus->master_state = ASPEED_I2C_MASTER_STOP;
 381         writel(ASPEED_I2CD_M_STOP_CMD, bus->base + ASPEED_I2C_CMD_REG);
 382 }
 383
 384 /* precondition: bus.lock has been acquired. */
 385 static void aspeed_i2c_next_msg_or_stop(struct aspeed_i2c_bus *bus)
 386 {
 387         if (bus->msgs_index + 1 < bus->msgs_count) {
 388                 bus->msgs_index++;
 389                 aspeed_i2c_do_start(bus);
 390         } else {
 391                 aspeed_i2c_do_stop(bus);
 392         }
 393 }
 394
 395 static int aspeed_i2c_is_irq_error(u32 irq_status)
 396 {
 397         if (irq_status & ASPEED_I2CD_INTR_ARBIT_LOSS)
 398                 return -EAGAIN;
 399         if (irq_status & (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |
 400                           ASPEED_I2CD_INTR_SCL_TIMEOUT))
 401                 return -EBUSY;
 402         if (irq_status & (ASPEED_I2CD_INTR_ABNORMAL))
 403                 return -EPROTO;
 404
 405         return 0;
 406 }
 407
 408 static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 409 {
 410         u32 irq_handled = 0, command = 0;
 411         struct i2c_msg *msg;
 412         u8 recv_byte;
 413         int ret;
 414
 415         if (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE) {
 416                 bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
 417                 irq_handled |= ASPEED_I2CD_INTR_BUS_RECOVER_DONE;
 418                 goto out_complete;
 419         }
 420
 421         /*
 422          * We encountered an interrupt that reports an error: the hardware
 423          * should clear the command queue effectively taking us back to the
 424          * INACTIVE state.
 425          */
 426         ret = aspeed_i2c_is_irq_error(irq_status);
 427         if (ret) {
 428                 dev_dbg(bus->dev, "received error interrupt: 0x%08x\n",
 429                         irq_status);
 430                 irq_handled |= (irq_status & ASPEED_I2CD_INTR_MASTER_ERRORS);
 431                 if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
 432                         bus->cmd_err = ret;
 433                         bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
 434                         goto out_complete;
 435                 }
 436         }
 437
 438         /* Master is not currently active, irq was for someone else. */
 439         if (bus->master_state == ASPEED_I2C_MASTER_INACTIVE ||
 440             bus->master_state == ASPEED_I2C_MASTER_PENDING)
 441                 goto out_no_complete;
 442
 443         /* We are in an invalid state; reset bus to a known state. */
 444         if (!bus->msgs) {
 445                 dev_err(bus->dev, "bus in unknown state. irq_status: 0x%x\n",
 446                         irq_status);
 447                 bus->cmd_err = -EIO;
 448                 if (bus->master_state != ASPEED_I2C_MASTER_STOP &&
 449                     bus->master_state != ASPEED_I2C_MASTER_INACTIVE)
 450                         aspeed_i2c_do_stop(bus);
 451                 goto out_no_complete;
 452         }
 453         msg = &bus->msgs[bus->msgs_index];
 454
 455         /*
 456          * START is a special case because we still have to handle a subsequent
 457          * TX or RX immediately after we handle it, so we handle it here and
 458          * then update the state and handle the new state below.
 459          */
 460         if (bus->master_state == ASPEED_I2C_MASTER_START) {
 461 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 462                 /*
 463                  * If a peer master starts a xfer immediately after it queues a
 464                  * master command, clear the queued master command and change
 465                  * its state to 'pending'. To simplify handling of pending
 466                  * cases, it uses S/W solution instead of H/W command queue
 467                  * handling.
 468                  */
 469                 if (unlikely(irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH)) {
 470                         writel(readl(bus->base + ASPEED_I2C_CMD_REG) &
 471                                 ~ASPEED_I2CD_MASTER_CMDS_MASK,
 472                                bus->base + ASPEED_I2C_CMD_REG);
 473                         bus->master_state = ASPEED_I2C_MASTER_PENDING;
 474                         dev_dbg(bus->dev,
 475                                 "master goes pending due to a slave start\n");
 476                         goto out_no_complete;
 477                 }
 478 #endif /* CONFIG_I2C_SLAVE */
 479                 if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
 480                         if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_NAK))) {
 481                                 bus->cmd_err = -ENXIO;
 482                                 bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
 483                                 goto out_complete;
 484                         }
 485                         pr_devel("no slave present at %02x\n", msg->addr);
 486                         irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
 487                         bus->cmd_err = -ENXIO;
 488                         aspeed_i2c_do_stop(bus);
 489                         goto out_no_complete;
 490                 }
 491                 irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
 492                 if (msg->len == 0) { /* SMBUS_QUICK */
 493                         aspeed_i2c_do_stop(bus);
 494                         goto out_no_complete;
 495                 }
 496                 if (msg->flags & I2C_M_RD)
 497                         bus->master_state = ASPEED_I2C_MASTER_RX_FIRST;
 498                 else
 499                         bus->master_state = ASPEED_I2C_MASTER_TX_FIRST;
 500         }
 501
 502         switch (bus->master_state) {
 503         case ASPEED_I2C_MASTER_TX:
 504                 if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_NAK)) {
 505                         dev_dbg(bus->dev, "slave NACKed TX\n");
 506                         irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
 507                         goto error_and_stop;
 508                 } else if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
 509                         dev_err(bus->dev, "slave failed to ACK TX\n");
 510                         goto error_and_stop;
 511                 }
 512                 irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
 513                 fallthrough;
 514         case ASPEED_I2C_MASTER_TX_FIRST:
 515                 if (bus->buf_index < msg->len) {
 516                         bus->master_state = ASPEED_I2C_MASTER_TX;
 517                         writel(msg->buf[bus->buf_index++],
 518                                bus->base + ASPEED_I2C_BYTE_BUF_REG);
 519                         writel(ASPEED_I2CD_M_TX_CMD,
 520                                bus->base + ASPEED_I2C_CMD_REG);
 521                 } else {
 522                         aspeed_i2c_next_msg_or_stop(bus);
 523                 }
 524                 goto out_no_complete;
 525         case ASPEED_I2C_MASTER_RX_FIRST:
 526                 /* RX may not have completed yet (only address cycle) */
 527                 if (!(irq_status & ASPEED_I2CD_INTR_RX_DONE))
 528                         goto out_no_complete;
 529                 fallthrough;
 530         case ASPEED_I2C_MASTER_RX:
 531                 if (unlikely(!(irq_status & ASPEED_I2CD_INTR_RX_DONE))) {
 532                         dev_err(bus->dev, "master failed to RX\n");
 533                         goto error_and_stop;
 534                 }
 535                 irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
 536
 537                 recv_byte = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
 538                 msg->buf[bus->buf_index++] = recv_byte;
 539
 540                 if (msg->flags & I2C_M_RECV_LEN) {
 541                         if (unlikely(recv_byte > I2C_SMBUS_BLOCK_MAX)) {
 542                                 bus->cmd_err = -EPROTO;
 543                                 aspeed_i2c_do_stop(bus);
 544                                 goto out_no_complete;
 545                         }
 546                         msg->len = recv_byte +
 547                                         ((msg->flags & I2C_CLIENT_PEC) ? 2 : 1);
 548                         msg->flags &= ~I2C_M_RECV_LEN;
 549                 }
 550
 551                 if (bus->buf_index < msg->len) {
 552                         bus->master_state = ASPEED_I2C_MASTER_RX;
 553                         command = ASPEED_I2CD_M_RX_CMD;
 554                         if (bus->buf_index + 1 == msg->len)
 555                                 command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
 556                         writel(command, bus->base + ASPEED_I2C_CMD_REG);
 557                 } else {
 558                         aspeed_i2c_next_msg_or_stop(bus);
 559                 }
 560                 goto out_no_complete;
 561         case ASPEED_I2C_MASTER_STOP:
 562                 if (unlikely(!(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))) {
 563                         dev_err(bus->dev,
 564                                 "master failed to STOP. irq_status:0x%x\n",
 565                                 irq_status);
 566                         bus->cmd_err = -EIO;
 567                         /* Do not STOP as we have already tried. */
 568                 } else {
 569                         irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
 570                 }
 571
 572                 bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
 573                 goto out_complete;
 574         case ASPEED_I2C_MASTER_INACTIVE:
 575                 dev_err(bus->dev,
 576                         "master received interrupt 0x%08x, but is inactive\n",
 577                         irq_status);
 578                 bus->cmd_err = -EIO;
 579                 /* Do not STOP as we should be inactive. */
 580                 goto out_complete;
 581         default:
 582                 WARN(1, "unknown master state\n");
 583                 bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
 584                 bus->cmd_err = -EINVAL;
 585                 goto out_complete;
 586         }
 587 error_and_stop:
 588         bus->cmd_err = -EIO;
 589         aspeed_i2c_do_stop(bus);
 590         goto out_no_complete;
 591 out_complete:
 592         bus->msgs = NULL;
 593         if (bus->cmd_err)
 594                 bus->master_xfer_result = bus->cmd_err;
 595         else
 596                 bus->master_xfer_result = bus->msgs_index + 1;
 597         complete(&bus->cmd_complete);
 598 out_no_complete:
 599         return irq_handled;
 600 }
 601
 602 static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
 603 {
 604         struct aspeed_i2c_bus *bus = dev_id;
 605         u32 irq_received, irq_remaining, irq_handled;
 606
 607         spin_lock(&bus->lock);
 608         irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
 609         /* Ack all interrupts except for Rx done */
 610         writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
 611                bus->base + ASPEED_I2C_INTR_STS_REG);
 612         readl(bus->base + ASPEED_I2C_INTR_STS_REG);
 613         irq_received &= ASPEED_I2CD_INTR_RECV_MASK;
 614         irq_remaining = irq_received;
 615
 616 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 617         /*
 618          * In most cases, interrupt bits will be set one by one, although
 619          * multiple interrupt bits could be set at the same time. It's also
 620          * possible that master interrupt bits could be set along with slave
 621          * interrupt bits. Each case needs to be handled using corresponding
 622          * handlers depending on the current state.
 623          */
 624         if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE &&
 625             bus->master_state != ASPEED_I2C_MASTER_PENDING) {
 626                 irq_handled = aspeed_i2c_master_irq(bus, irq_remaining);
 627                 irq_remaining &= ~irq_handled;
 628                 if (irq_remaining)
 629                         irq_handled |= aspeed_i2c_slave_irq(bus, irq_remaining);
 630         } else {
 631                 irq_handled = aspeed_i2c_slave_irq(bus, irq_remaining);
 632                 irq_remaining &= ~irq_handled;
 633                 if (irq_remaining)
 634                         irq_handled |= aspeed_i2c_master_irq(bus,
 635                                                              irq_remaining);
 636         }
 637
 638         /*
 639          * Start a pending master command at here if a slave operation is
 640          * completed.
 641          */
 642         if (bus->master_state == ASPEED_I2C_MASTER_PENDING &&
 643             bus->slave_state == ASPEED_I2C_SLAVE_INACTIVE)
 644                 aspeed_i2c_do_start(bus);
 645 #else
 646         irq_handled = aspeed_i2c_master_irq(bus, irq_remaining);
 647 #endif /* CONFIG_I2C_SLAVE */
 648
 649         irq_remaining &= ~irq_handled;
 650         if (irq_remaining)
 651                 dev_err(bus->dev,
 652                         "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
 653                         irq_received, irq_handled);
 654
 655         /* Ack Rx done */
 656         if (irq_received & ASPEED_I2CD_INTR_RX_DONE) {
 657                 writel(ASPEED_I2CD_INTR_RX_DONE,
 658                        bus->base + ASPEED_I2C_INTR_STS_REG);
 659                 readl(bus->base + ASPEED_I2C_INTR_STS_REG);
 660         }
 661         spin_unlock(&bus->lock);
 662         return irq_remaining ? IRQ_NONE : IRQ_HANDLED;
 663 }
 664
 665 static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
 666                                   struct i2c_msg *msgs, int num)
 667 {
 668         struct aspeed_i2c_bus *bus = i2c_get_adapdata(adap);
 669         unsigned long time_left, flags;
 670
 671         spin_lock_irqsave(&bus->lock, flags);
 672         bus->cmd_err = 0;
 673
 674         /* If bus is busy in a single master environment, attempt recovery. */
 675         if (!bus->multi_master &&
 676             (readl(bus->base + ASPEED_I2C_CMD_REG) &
 677              ASPEED_I2CD_BUS_BUSY_STS)) {
 678                 int ret;
 679
 680                 spin_unlock_irqrestore(&bus->lock, flags);
 681                 ret = aspeed_i2c_recover_bus(bus);
 682                 if (ret)
 683                         return ret;
 684                 spin_lock_irqsave(&bus->lock, flags);
 685         }
 686
 687         bus->cmd_err = 0;
 688         bus->msgs = msgs;
 689         bus->msgs_index = 0;
 690         bus->msgs_count = num;
 691
 692         reinit_completion(&bus->cmd_complete);
 693         aspeed_i2c_do_start(bus);
 694         spin_unlock_irqrestore(&bus->lock, flags);
 695
 696         time_left = wait_for_completion_timeout(&bus->cmd_complete,
 697                                                 bus->adap.timeout);
 698
 699         if (time_left == 0) {
 700                 /*
 701                  * If timed out and bus is still busy in a multi master
 702                  * environment, attempt recovery at here.
 703                  */
 704                 if (bus->multi_master &&
 705                     (readl(bus->base + ASPEED_I2C_CMD_REG) &
 706                      ASPEED_I2CD_BUS_BUSY_STS))
 707                         aspeed_i2c_recover_bus(bus);
 708
 709                 /*
 710                  * If timed out and the state is still pending, drop the pending
 711                  * master command.
 712                  */
 713                 spin_lock_irqsave(&bus->lock, flags);
 714                 if (bus->master_state == ASPEED_I2C_MASTER_PENDING)
 715                         bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
 716                 spin_unlock_irqrestore(&bus->lock, flags);
 717
 718                 return -ETIMEDOUT;
 719         }
 720
 721         return bus->master_xfer_result;
 722 }
 723
 724 static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
 725 {
 726         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
 727 }
 728
 729 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 730 /* precondition: bus.lock has been acquired. */
 731 static void __aspeed_i2c_reg_slave(struct aspeed_i2c_bus *bus, u16 slave_addr)
 732 {
 733         u32 addr_reg_val, func_ctrl_reg_val;
 734
 735         /*
 736          * Set slave addr.  Reserved bits can all safely be written with zeros
 737          * on all of ast2[456]00, so zero everything else to ensure we only
 738          * enable a single slave address (ast2500 has two, ast2600 has three,
 739          * the enable bits for which are also in this register) so that we don't
 740          * end up with additional phantom devices responding on the bus.
 741          */
 742         addr_reg_val = slave_addr & ASPEED_I2CD_DEV_ADDR_MASK;
 743         writel(addr_reg_val, bus->base + ASPEED_I2C_DEV_ADDR_REG);
 744
 745         /* Turn on slave mode. */
 746         func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
 747         func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
 748         writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
 749 }
 750
 751 static int aspeed_i2c_reg_slave(struct i2c_client *client)
 752 {
 753         struct aspeed_i2c_bus *bus = i2c_get_adapdata(client->adapter);
 754         unsigned long flags;
 755
 756         spin_lock_irqsave(&bus->lock, flags);
 757         if (bus->slave) {
 758                 spin_unlock_irqrestore(&bus->lock, flags);
 759                 return -EINVAL;
 760         }
 761
 762         __aspeed_i2c_reg_slave(bus, client->addr);
 763
 764         bus->slave = client;
 765         bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
 766         spin_unlock_irqrestore(&bus->lock, flags);
 767
 768         return 0;
 769 }
 770
 771 static int aspeed_i2c_unreg_slave(struct i2c_client *client)
 772 {
 773         struct aspeed_i2c_bus *bus = i2c_get_adapdata(client->adapter);
 774         u32 func_ctrl_reg_val;
 775         unsigned long flags;
 776
 777         spin_lock_irqsave(&bus->lock, flags);
 778         if (!bus->slave) {
 779                 spin_unlock_irqrestore(&bus->lock, flags);
 780                 return -EINVAL;
 781         }
 782
 783         /* Turn off slave mode. */
 784         func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
 785         func_ctrl_reg_val &= ~ASPEED_I2CD_SLAVE_EN;
 786         writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
 787
 788         bus->slave = NULL;
 789         spin_unlock_irqrestore(&bus->lock, flags);
 790
 791         return 0;
 792 }
 793 #endif /* CONFIG_I2C_SLAVE */
 794
 795 static const struct i2c_algorithm aspeed_i2c_algo = {
 796         .master_xfer    = aspeed_i2c_master_xfer,
 797         .functionality  = aspeed_i2c_functionality,
 798 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 799         .reg_slave      = aspeed_i2c_reg_slave,
 800         .unreg_slave    = aspeed_i2c_unreg_slave,
 801 #endif /* CONFIG_I2C_SLAVE */
 802 };
 803
 804 static u32 aspeed_i2c_get_clk_reg_val(struct device *dev,
 805                                       u32 clk_high_low_mask,
 806                                       u32 divisor)
 807 {
 808         u32 base_clk_divisor, clk_high_low_max, clk_high, clk_low, tmp;
 809
 810         /*
 811          * SCL_high and SCL_low represent a value 1 greater than what is stored
 812          * since a zero divider is meaningless. Thus, the max value each can
 813          * store is every bit set + 1. Since SCL_high and SCL_low are added
 814          * together (see below), the max value of both is the max value of one
 815          * them times two.
 816          */
 817         clk_high_low_max = (clk_high_low_mask + 1) * 2;
 818
 819         /*
 820          * The actual clock frequency of SCL is:
 821          *      SCL_freq = APB_freq / (base_freq * (SCL_high + SCL_low))
 822          *               = APB_freq / divisor
 823          * where base_freq is a programmable clock divider; its value is
 824          *      base_freq = 1 << base_clk_divisor
 825          * SCL_high is the number of base_freq clock cycles that SCL stays high
 826          * and SCL_low is the number of base_freq clock cycles that SCL stays
 827          * low for a period of SCL.
 828          * The actual register has a minimum SCL_high and SCL_low minimum of 1;
 829          * thus, they start counting at zero. So
 830          *      SCL_high = clk_high + 1
 831          *      SCL_low  = clk_low + 1
 832          * Thus,
 833          *      SCL_freq = APB_freq /
 834          *              ((1 << base_clk_divisor) * (clk_high + 1 + clk_low + 1))
 835          * The documentation recommends clk_high >= clk_high_max / 2 and
 836          * clk_low >= clk_low_max / 2 - 1 when possible; this last constraint
 837          * gives us the following solution:
 838          */
 839         base_clk_divisor = divisor > clk_high_low_max ?
 840                         ilog2((divisor - 1) / clk_high_low_max) + 1 : 0;
 841
 842         if (base_clk_divisor > ASPEED_I2CD_TIME_BASE_DIVISOR_MASK) {
 843                 base_clk_divisor = ASPEED_I2CD_TIME_BASE_DIVISOR_MASK;
 844                 clk_low = clk_high_low_mask;
 845                 clk_high = clk_high_low_mask;
 846                 dev_err(dev,
 847                         "clamping clock divider: divider requested, %u, is greater than largest possible divider, %u.\n",
 848                         divisor, (1 << base_clk_divisor) * clk_high_low_max);
 849         } else {
 850                 tmp = (divisor + (1 << base_clk_divisor) - 1)
 851                                 >> base_clk_divisor;
 852                 clk_low = tmp / 2;
 853                 clk_high = tmp - clk_low;
 854
 855                 if (clk_high)
 856                         clk_high--;
 857
 858                 if (clk_low)
 859                         clk_low--;
 860         }
 861
 862
 863         return ((clk_high << ASPEED_I2CD_TIME_SCL_HIGH_SHIFT)
 864                 & ASPEED_I2CD_TIME_SCL_HIGH_MASK)
 865                         | ((clk_low << ASPEED_I2CD_TIME_SCL_LOW_SHIFT)
 866                            & ASPEED_I2CD_TIME_SCL_LOW_MASK)
 867                         | (base_clk_divisor
 868                            & ASPEED_I2CD_TIME_BASE_DIVISOR_MASK);
 869 }
 870
 871 static u32 aspeed_i2c_24xx_get_clk_reg_val(struct device *dev, u32 divisor)
 872 {
 873         /*
 874          * clk_high and clk_low are each 3 bits wide, so each can hold a max
 875          * value of 8 giving a clk_high_low_max of 16.
 876          */
 877         return aspeed_i2c_get_clk_reg_val(dev, GENMASK(2, 0), divisor);
 878 }
 879
 880 static u32 aspeed_i2c_25xx_get_clk_reg_val(struct device *dev, u32 divisor)
 881 {
 882         /*
 883          * clk_high and clk_low are each 4 bits wide, so each can hold a max
 884          * value of 16 giving a clk_high_low_max of 32.
 885          */
 886         return aspeed_i2c_get_clk_reg_val(dev, GENMASK(3, 0), divisor);
 887 }
 888
 889 /* precondition: bus.lock has been acquired. */
 890 static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
 891 {
 892         u32 divisor, clk_reg_val;
 893
 894         divisor = DIV_ROUND_UP(bus->parent_clk_frequency, bus->bus_frequency);
 895         clk_reg_val = readl(bus->base + ASPEED_I2C_AC_TIMING_REG1);
 896         clk_reg_val &= (ASPEED_I2CD_TIME_TBUF_MASK |
 897                         ASPEED_I2CD_TIME_THDSTA_MASK |
 898                         ASPEED_I2CD_TIME_TACST_MASK);
 899         clk_reg_val |= bus->get_clk_reg_val(bus->dev, divisor);
 900         writel(clk_reg_val, bus->base + ASPEED_I2C_AC_TIMING_REG1);
 901         writel(ASPEED_NO_TIMEOUT_CTRL, bus->base + ASPEED_I2C_AC_TIMING_REG2);
 902
 903         return 0;
 904 }
 905
 906 /* precondition: bus.lock has been acquired. */
 907 static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
 908                              struct platform_device *pdev)
 909 {
 910         u32 fun_ctrl_reg = ASPEED_I2CD_MASTER_EN;
 911         int ret;
 912
 913         /* Disable everything. */
 914         writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);
 915
 916         ret = aspeed_i2c_init_clk(bus);
 917         if (ret < 0)
 918                 return ret;
 919
 920         if (of_property_read_bool(pdev->dev.of_node, "multi-master"))
 921                 bus->multi_master = true;
 922         else
 923                 fun_ctrl_reg |= ASPEED_I2CD_MULTI_MASTER_DIS;
 924
 925         /* Enable Master Mode */
 926         writel(readl(bus->base + ASPEED_I2C_FUN_CTRL_REG) | fun_ctrl_reg,
 927                bus->base + ASPEED_I2C_FUN_CTRL_REG);
 928
 929 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 930         /* If slave has already been registered, re-enable it. */
 931         if (bus->slave)
 932                 __aspeed_i2c_reg_slave(bus, bus->slave->addr);
 933 #endif /* CONFIG_I2C_SLAVE */
 934
 935         /* Set interrupt generation of I2C controller */
 936         writel(ASPEED_I2CD_INTR_ALL, bus->base + ASPEED_I2C_INTR_CTRL_REG);
 937
 938         return 0;
 939 }
 940
 941 static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus)
 942 {
 943         struct platform_device *pdev = to_platform_device(bus->dev);
 944         unsigned long flags;
 945         int ret;
 946
 947         spin_lock_irqsave(&bus->lock, flags);
 948
 949         /* Disable and ack all interrupts. */
 950         writel(0, bus->base + ASPEED_I2C_INTR_CTRL_REG);
 951         writel(0xffffffff, bus->base + ASPEED_I2C_INTR_STS_REG);
 952
 953         ret = aspeed_i2c_init(bus, pdev);
 954
 955         spin_unlock_irqrestore(&bus->lock, flags);
 956
 957         return ret;
 958 }
 959
 960 static const struct of_device_id aspeed_i2c_bus_of_table[] = {
 961         {
 962                 .compatible = "aspeed,ast2400-i2c-bus",
 963                 .data = aspeed_i2c_24xx_get_clk_reg_val,
 964         },
 965         {
 966                 .compatible = "aspeed,ast2500-i2c-bus",
 967                 .data = aspeed_i2c_25xx_get_clk_reg_val,
 968         },
 969         {
 970                 .compatible = "aspeed,ast2600-i2c-bus",
 971                 .data = aspeed_i2c_25xx_get_clk_reg_val,
 972         },
 973         { },
 974 };
 975 MODULE_DEVICE_TABLE(of, aspeed_i2c_bus_of_table);
 976
 977 static int aspeed_i2c_probe_bus(struct platform_device *pdev)
 978 {
 979         const struct of_device_id *match;
 980         struct aspeed_i2c_bus *bus;
 981         struct clk *parent_clk;
 982         int irq, ret;
 983
 984         bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
 985         if (!bus)
 986                 return -ENOMEM;
 987
 988         bus->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
 989         if (IS_ERR(bus->base))
 990                 return PTR_ERR(bus->base);
 991
 992         parent_clk = devm_clk_get(&pdev->dev, NULL);
 993         if (IS_ERR(parent_clk))
 994                 return PTR_ERR(parent_clk);
 995         bus->parent_clk_frequency = clk_get_rate(parent_clk);
 996         /* We just need the clock rate, we don't actually use the clk object. */
 997         devm_clk_put(&pdev->dev, parent_clk);
 998
 999         bus->rst = devm_reset_control_get_shared(&pdev->dev, NULL);
1000         if (IS_ERR(bus->rst)) {
1001                 dev_err(&pdev->dev,
1002                         "missing or invalid reset controller device tree entry\n");
1003                 return PTR_ERR(bus->rst);
1004         }
1005         reset_control_deassert(bus->rst);
1006
1007         ret = of_property_read_u32(pdev->dev.of_node,
1008                                    "bus-frequency", &bus->bus_frequency);
1009         if (ret < 0) {
1010                 dev_err(&pdev->dev,
1011                         "Could not read bus-frequency property\n");
1012                 bus->bus_frequency = I2C_MAX_STANDARD_MODE_FREQ;
1013         }
1014
1015         match = of_match_node(aspeed_i2c_bus_of_table, pdev->dev.of_node);
1016         if (!match)
1017                 bus->get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val;
1018         else
1019                 bus->get_clk_reg_val = (u32 (*)(struct device *, u32))
1020                                 match->data;
1021
1022         /* Initialize the I2C adapter */
1023         spin_lock_init(&bus->lock);
1024         init_completion(&bus->cmd_complete);
1025         bus->adap.owner = THIS_MODULE;
1026         bus->adap.retries = 0;
1027         bus->adap.algo = &aspeed_i2c_algo;
1028         bus->adap.dev.parent = &pdev->dev;
1029         bus->adap.dev.of_node = pdev->dev.of_node;
1030         strscpy(bus->adap.name, pdev->name, sizeof(bus->adap.name));
1031         i2c_set_adapdata(&bus->adap, bus);
1032
1033         bus->dev = &pdev->dev;
1034
1035         /* Clean up any left over interrupt state. */
1036         writel(0, bus->base + ASPEED_I2C_INTR_CTRL_REG);
1037         writel(0xffffffff, bus->base + ASPEED_I2C_INTR_STS_REG);
1038         /*
1039          * bus.lock does not need to be held because the interrupt handler has
1040          * not been enabled yet.
1041          */
1042         ret = aspeed_i2c_init(bus, pdev);
1043         if (ret < 0)
1044                 return ret;
1045
1046         irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
1047         ret = devm_request_irq(&pdev->dev, irq, aspeed_i2c_bus_irq,
1048                                0, dev_name(&pdev->dev), bus);
1049         if (ret < 0)
1050                 return ret;
1051
1052         ret = i2c_add_adapter(&bus->adap);
1053         if (ret < 0)
1054                 return ret;
1055
1056         platform_set_drvdata(pdev, bus);
1057
1058         dev_info(bus->dev, "i2c bus %d registered, irq %d\n",
1059                  bus->adap.nr, irq);
1060
1061         return 0;
1062 }
1063
1064 static void aspeed_i2c_remove_bus(struct platform_device *pdev)
1065 {
1066         struct aspeed_i2c_bus *bus = platform_get_drvdata(pdev);
1067         unsigned long flags;
1068
1069         spin_lock_irqsave(&bus->lock, flags);
1070
1071         /* Disable everything. */
1072         writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);
1073         writel(0, bus->base + ASPEED_I2C_INTR_CTRL_REG);
1074
1075         spin_unlock_irqrestore(&bus->lock, flags);
1076
1077         reset_control_assert(bus->rst);
1078
1079         i2c_del_adapter(&bus->adap);
1080 }
1081
1082 static struct platform_driver aspeed_i2c_bus_driver = {
1083         .probe          = aspeed_i2c_probe_bus,
1084         .remove_new     = aspeed_i2c_remove_bus,
1085         .driver         = {
1086                 .name           = "aspeed-i2c-bus",
1087                 .of_match_table = aspeed_i2c_bus_of_table,
1088         },
1089 };
1090 module_platform_driver(aspeed_i2c_bus_driver);
1091
1092 MODULE_AUTHOR("Brendan Higgins <brendanhiggins@google.com>");
1093 MODULE_DESCRIPTION("Aspeed I2C Bus Driver");
1094 MODULE_LICENSE("GPL v2");