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 int 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 return 0; 1082 } 1083 1084 static struct platform_driver aspeed_i2c_bus_driver = { 1085 .probe = aspeed_i2c_probe_bus, 1086 .remove = aspeed_i2c_remove_bus, 1087 .driver = { 1088 .name = "aspeed-i2c-bus", 1089 .of_match_table = aspeed_i2c_bus_of_table, 1090 }, 1091 }; 1092 module_platform_driver(aspeed_i2c_bus_driver); 1093 1094 MODULE_AUTHOR("Brendan Higgins <brendanhiggins@google.com>"); 1095 MODULE_DESCRIPTION("Aspeed I2C Bus Driver"); 1096 MODULE_LICENSE("GPL v2"); 1097