1 /* 2 * I2C bus driver for the Cadence I2C controller. 3 * 4 * Copyright (C) 2009 - 2014 Xilinx, Inc. 5 * 6 * This program is free software; you can redistribute it 7 * and/or modify it under the terms of the GNU General Public 8 * License as published by the Free Software Foundation; 9 * either version 2 of the License, or (at your option) any 10 * later version. 11 */ 12 13 #include <linux/clk.h> 14 #include <linux/delay.h> 15 #include <linux/i2c.h> 16 #include <linux/interrupt.h> 17 #include <linux/io.h> 18 #include <linux/module.h> 19 #include <linux/platform_device.h> 20 #include <linux/of.h> 21 #include <linux/pm_runtime.h> 22 23 /* Register offsets for the I2C device. */ 24 #define CDNS_I2C_CR_OFFSET 0x00 /* Control Register, RW */ 25 #define CDNS_I2C_SR_OFFSET 0x04 /* Status Register, RO */ 26 #define CDNS_I2C_ADDR_OFFSET 0x08 /* I2C Address Register, RW */ 27 #define CDNS_I2C_DATA_OFFSET 0x0C /* I2C Data Register, RW */ 28 #define CDNS_I2C_ISR_OFFSET 0x10 /* IRQ Status Register, RW */ 29 #define CDNS_I2C_XFER_SIZE_OFFSET 0x14 /* Transfer Size Register, RW */ 30 #define CDNS_I2C_TIME_OUT_OFFSET 0x1C /* Time Out Register, RW */ 31 #define CDNS_I2C_IER_OFFSET 0x24 /* IRQ Enable Register, WO */ 32 #define CDNS_I2C_IDR_OFFSET 0x28 /* IRQ Disable Register, WO */ 33 34 /* Control Register Bit mask definitions */ 35 #define CDNS_I2C_CR_HOLD BIT(4) /* Hold Bus bit */ 36 #define CDNS_I2C_CR_ACK_EN BIT(3) 37 #define CDNS_I2C_CR_NEA BIT(2) 38 #define CDNS_I2C_CR_MS BIT(1) 39 /* Read or Write Master transfer 0 = Transmitter, 1 = Receiver */ 40 #define CDNS_I2C_CR_RW BIT(0) 41 /* 1 = Auto init FIFO to zeroes */ 42 #define CDNS_I2C_CR_CLR_FIFO BIT(6) 43 #define CDNS_I2C_CR_DIVA_SHIFT 14 44 #define CDNS_I2C_CR_DIVA_MASK (3 << CDNS_I2C_CR_DIVA_SHIFT) 45 #define CDNS_I2C_CR_DIVB_SHIFT 8 46 #define CDNS_I2C_CR_DIVB_MASK (0x3f << CDNS_I2C_CR_DIVB_SHIFT) 47 48 /* Status Register Bit mask definitions */ 49 #define CDNS_I2C_SR_BA BIT(8) 50 #define CDNS_I2C_SR_RXDV BIT(5) 51 52 /* 53 * I2C Address Register Bit mask definitions 54 * Normal addressing mode uses [6:0] bits. Extended addressing mode uses [9:0] 55 * bits. A write access to this register always initiates a transfer if the I2C 56 * is in master mode. 57 */ 58 #define CDNS_I2C_ADDR_MASK 0x000003FF /* I2C Address Mask */ 59 60 /* 61 * I2C Interrupt Registers Bit mask definitions 62 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same 63 * bit definitions. 64 */ 65 #define CDNS_I2C_IXR_ARB_LOST BIT(9) 66 #define CDNS_I2C_IXR_RX_UNF BIT(7) 67 #define CDNS_I2C_IXR_TX_OVF BIT(6) 68 #define CDNS_I2C_IXR_RX_OVF BIT(5) 69 #define CDNS_I2C_IXR_SLV_RDY BIT(4) 70 #define CDNS_I2C_IXR_TO BIT(3) 71 #define CDNS_I2C_IXR_NACK BIT(2) 72 #define CDNS_I2C_IXR_DATA BIT(1) 73 #define CDNS_I2C_IXR_COMP BIT(0) 74 75 #define CDNS_I2C_IXR_ALL_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ 76 CDNS_I2C_IXR_RX_UNF | \ 77 CDNS_I2C_IXR_TX_OVF | \ 78 CDNS_I2C_IXR_RX_OVF | \ 79 CDNS_I2C_IXR_SLV_RDY | \ 80 CDNS_I2C_IXR_TO | \ 81 CDNS_I2C_IXR_NACK | \ 82 CDNS_I2C_IXR_DATA | \ 83 CDNS_I2C_IXR_COMP) 84 85 #define CDNS_I2C_IXR_ERR_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ 86 CDNS_I2C_IXR_RX_UNF | \ 87 CDNS_I2C_IXR_TX_OVF | \ 88 CDNS_I2C_IXR_RX_OVF | \ 89 CDNS_I2C_IXR_NACK) 90 91 #define CDNS_I2C_ENABLED_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ 92 CDNS_I2C_IXR_RX_UNF | \ 93 CDNS_I2C_IXR_TX_OVF | \ 94 CDNS_I2C_IXR_RX_OVF | \ 95 CDNS_I2C_IXR_NACK | \ 96 CDNS_I2C_IXR_DATA | \ 97 CDNS_I2C_IXR_COMP) 98 99 #define CDNS_I2C_TIMEOUT msecs_to_jiffies(1000) 100 /* timeout for pm runtime autosuspend */ 101 #define CNDS_I2C_PM_TIMEOUT 1000 /* ms */ 102 103 #define CDNS_I2C_FIFO_DEPTH 16 104 /* FIFO depth at which the DATA interrupt occurs */ 105 #define CDNS_I2C_DATA_INTR_DEPTH (CDNS_I2C_FIFO_DEPTH - 2) 106 #define CDNS_I2C_MAX_TRANSFER_SIZE 255 107 /* Transfer size in multiples of data interrupt depth */ 108 #define CDNS_I2C_TRANSFER_SIZE (CDNS_I2C_MAX_TRANSFER_SIZE - 3) 109 110 #define DRIVER_NAME "cdns-i2c" 111 112 #define CDNS_I2C_SPEED_MAX 400000 113 #define CDNS_I2C_SPEED_DEFAULT 100000 114 115 #define CDNS_I2C_DIVA_MAX 4 116 #define CDNS_I2C_DIVB_MAX 64 117 118 #define CDNS_I2C_TIMEOUT_MAX 0xFF 119 120 #define CDNS_I2C_BROKEN_HOLD_BIT BIT(0) 121 122 #define cdns_i2c_readreg(offset) readl_relaxed(id->membase + offset) 123 #define cdns_i2c_writereg(val, offset) writel_relaxed(val, id->membase + offset) 124 125 /** 126 * struct cdns_i2c - I2C device private data structure 127 * 128 * @dev: Pointer to device structure 129 * @membase: Base address of the I2C device 130 * @adap: I2C adapter instance 131 * @p_msg: Message pointer 132 * @err_status: Error status in Interrupt Status Register 133 * @xfer_done: Transfer complete status 134 * @p_send_buf: Pointer to transmit buffer 135 * @p_recv_buf: Pointer to receive buffer 136 * @send_count: Number of bytes still expected to send 137 * @recv_count: Number of bytes still expected to receive 138 * @curr_recv_count: Number of bytes to be received in current transfer 139 * @irq: IRQ number 140 * @input_clk: Input clock to I2C controller 141 * @i2c_clk: Maximum I2C clock speed 142 * @bus_hold_flag: Flag used in repeated start for clearing HOLD bit 143 * @clk: Pointer to struct clk 144 * @clk_rate_change_nb: Notifier block for clock rate changes 145 * @quirks: flag for broken hold bit usage in r1p10 146 */ 147 struct cdns_i2c { 148 struct device *dev; 149 void __iomem *membase; 150 struct i2c_adapter adap; 151 struct i2c_msg *p_msg; 152 int err_status; 153 struct completion xfer_done; 154 unsigned char *p_send_buf; 155 unsigned char *p_recv_buf; 156 unsigned int send_count; 157 unsigned int recv_count; 158 unsigned int curr_recv_count; 159 int irq; 160 unsigned long input_clk; 161 unsigned int i2c_clk; 162 unsigned int bus_hold_flag; 163 struct clk *clk; 164 struct notifier_block clk_rate_change_nb; 165 u32 quirks; 166 }; 167 168 struct cdns_platform_data { 169 u32 quirks; 170 }; 171 172 #define to_cdns_i2c(_nb) container_of(_nb, struct cdns_i2c, \ 173 clk_rate_change_nb) 174 175 /** 176 * cdns_i2c_clear_bus_hold - Clear bus hold bit 177 * @id: Pointer to driver data struct 178 * 179 * Helper to clear the controller's bus hold bit. 180 */ 181 static void cdns_i2c_clear_bus_hold(struct cdns_i2c *id) 182 { 183 u32 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 184 if (reg & CDNS_I2C_CR_HOLD) 185 cdns_i2c_writereg(reg & ~CDNS_I2C_CR_HOLD, CDNS_I2C_CR_OFFSET); 186 } 187 188 static inline bool cdns_is_holdquirk(struct cdns_i2c *id, bool hold_wrkaround) 189 { 190 return (hold_wrkaround && 191 (id->curr_recv_count == CDNS_I2C_FIFO_DEPTH + 1)); 192 } 193 194 /** 195 * cdns_i2c_isr - Interrupt handler for the I2C device 196 * @irq: irq number for the I2C device 197 * @ptr: void pointer to cdns_i2c structure 198 * 199 * This function handles the data interrupt, transfer complete interrupt and 200 * the error interrupts of the I2C device. 201 * 202 * Return: IRQ_HANDLED always 203 */ 204 static irqreturn_t cdns_i2c_isr(int irq, void *ptr) 205 { 206 unsigned int isr_status, avail_bytes, updatetx; 207 unsigned int bytes_to_send; 208 bool hold_quirk; 209 struct cdns_i2c *id = ptr; 210 /* Signal completion only after everything is updated */ 211 int done_flag = 0; 212 irqreturn_t status = IRQ_NONE; 213 214 isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET); 215 cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET); 216 217 /* Handling nack and arbitration lost interrupt */ 218 if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_ARB_LOST)) { 219 done_flag = 1; 220 status = IRQ_HANDLED; 221 } 222 223 /* 224 * Check if transfer size register needs to be updated again for a 225 * large data receive operation. 226 */ 227 updatetx = 0; 228 if (id->recv_count > id->curr_recv_count) 229 updatetx = 1; 230 231 hold_quirk = (id->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx; 232 233 /* When receiving, handle data interrupt and completion interrupt */ 234 if (id->p_recv_buf && 235 ((isr_status & CDNS_I2C_IXR_COMP) || 236 (isr_status & CDNS_I2C_IXR_DATA))) { 237 /* Read data if receive data valid is set */ 238 while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & 239 CDNS_I2C_SR_RXDV) { 240 /* 241 * Clear hold bit that was set for FIFO control if 242 * RX data left is less than FIFO depth, unless 243 * repeated start is selected. 244 */ 245 if ((id->recv_count < CDNS_I2C_FIFO_DEPTH) && 246 !id->bus_hold_flag) 247 cdns_i2c_clear_bus_hold(id); 248 249 *(id->p_recv_buf)++ = 250 cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET); 251 id->recv_count--; 252 id->curr_recv_count--; 253 254 if (cdns_is_holdquirk(id, hold_quirk)) 255 break; 256 } 257 258 /* 259 * The controller sends NACK to the slave when transfer size 260 * register reaches zero without considering the HOLD bit. 261 * This workaround is implemented for large data transfers to 262 * maintain transfer size non-zero while performing a large 263 * receive operation. 264 */ 265 if (cdns_is_holdquirk(id, hold_quirk)) { 266 /* wait while fifo is full */ 267 while (cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET) != 268 (id->curr_recv_count - CDNS_I2C_FIFO_DEPTH)) 269 ; 270 271 /* 272 * Check number of bytes to be received against maximum 273 * transfer size and update register accordingly. 274 */ 275 if (((int)(id->recv_count) - CDNS_I2C_FIFO_DEPTH) > 276 CDNS_I2C_TRANSFER_SIZE) { 277 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE, 278 CDNS_I2C_XFER_SIZE_OFFSET); 279 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE + 280 CDNS_I2C_FIFO_DEPTH; 281 } else { 282 cdns_i2c_writereg(id->recv_count - 283 CDNS_I2C_FIFO_DEPTH, 284 CDNS_I2C_XFER_SIZE_OFFSET); 285 id->curr_recv_count = id->recv_count; 286 } 287 } else if (id->recv_count && !hold_quirk && 288 !id->curr_recv_count) { 289 290 /* Set the slave address in address register*/ 291 cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, 292 CDNS_I2C_ADDR_OFFSET); 293 294 if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) { 295 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE, 296 CDNS_I2C_XFER_SIZE_OFFSET); 297 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE; 298 } else { 299 cdns_i2c_writereg(id->recv_count, 300 CDNS_I2C_XFER_SIZE_OFFSET); 301 id->curr_recv_count = id->recv_count; 302 } 303 } 304 305 /* Clear hold (if not repeated start) and signal completion */ 306 if ((isr_status & CDNS_I2C_IXR_COMP) && !id->recv_count) { 307 if (!id->bus_hold_flag) 308 cdns_i2c_clear_bus_hold(id); 309 done_flag = 1; 310 } 311 312 status = IRQ_HANDLED; 313 } 314 315 /* When sending, handle transfer complete interrupt */ 316 if ((isr_status & CDNS_I2C_IXR_COMP) && !id->p_recv_buf) { 317 /* 318 * If there is more data to be sent, calculate the 319 * space available in FIFO and fill with that many bytes. 320 */ 321 if (id->send_count) { 322 avail_bytes = CDNS_I2C_FIFO_DEPTH - 323 cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET); 324 if (id->send_count > avail_bytes) 325 bytes_to_send = avail_bytes; 326 else 327 bytes_to_send = id->send_count; 328 329 while (bytes_to_send--) { 330 cdns_i2c_writereg( 331 (*(id->p_send_buf)++), 332 CDNS_I2C_DATA_OFFSET); 333 id->send_count--; 334 } 335 } else { 336 /* 337 * Signal the completion of transaction and 338 * clear the hold bus bit if there are no 339 * further messages to be processed. 340 */ 341 done_flag = 1; 342 } 343 if (!id->send_count && !id->bus_hold_flag) 344 cdns_i2c_clear_bus_hold(id); 345 346 status = IRQ_HANDLED; 347 } 348 349 /* Update the status for errors */ 350 id->err_status = isr_status & CDNS_I2C_IXR_ERR_INTR_MASK; 351 if (id->err_status) 352 status = IRQ_HANDLED; 353 354 if (done_flag) 355 complete(&id->xfer_done); 356 357 return status; 358 } 359 360 /** 361 * cdns_i2c_mrecv - Prepare and start a master receive operation 362 * @id: pointer to the i2c device structure 363 */ 364 static void cdns_i2c_mrecv(struct cdns_i2c *id) 365 { 366 unsigned int ctrl_reg; 367 unsigned int isr_status; 368 369 id->p_recv_buf = id->p_msg->buf; 370 id->recv_count = id->p_msg->len; 371 372 /* Put the controller in master receive mode and clear the FIFO */ 373 ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 374 ctrl_reg |= CDNS_I2C_CR_RW | CDNS_I2C_CR_CLR_FIFO; 375 376 if (id->p_msg->flags & I2C_M_RECV_LEN) 377 id->recv_count = I2C_SMBUS_BLOCK_MAX + 1; 378 379 id->curr_recv_count = id->recv_count; 380 381 /* 382 * Check for the message size against FIFO depth and set the 383 * 'hold bus' bit if it is greater than FIFO depth. 384 */ 385 if (id->recv_count > CDNS_I2C_FIFO_DEPTH) 386 ctrl_reg |= CDNS_I2C_CR_HOLD; 387 388 cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET); 389 390 /* Clear the interrupts in interrupt status register */ 391 isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET); 392 cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET); 393 394 /* 395 * The no. of bytes to receive is checked against the limit of 396 * max transfer size. Set transfer size register with no of bytes 397 * receive if it is less than transfer size and transfer size if 398 * it is more. Enable the interrupts. 399 */ 400 if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) { 401 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE, 402 CDNS_I2C_XFER_SIZE_OFFSET); 403 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE; 404 } else { 405 cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET); 406 } 407 408 /* 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 /* Set the slave address in address register - triggers operation */ 414 cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, 415 CDNS_I2C_ADDR_OFFSET); 416 cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET); 417 } 418 419 /** 420 * cdns_i2c_msend - Prepare and start a master send operation 421 * @id: pointer to the i2c device 422 */ 423 static void cdns_i2c_msend(struct cdns_i2c *id) 424 { 425 unsigned int avail_bytes; 426 unsigned int bytes_to_send; 427 unsigned int ctrl_reg; 428 unsigned int isr_status; 429 430 id->p_recv_buf = NULL; 431 id->p_send_buf = id->p_msg->buf; 432 id->send_count = id->p_msg->len; 433 434 /* Set the controller in Master transmit mode and clear the FIFO. */ 435 ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 436 ctrl_reg &= ~CDNS_I2C_CR_RW; 437 ctrl_reg |= CDNS_I2C_CR_CLR_FIFO; 438 439 /* 440 * Check for the message size against FIFO depth and set the 441 * 'hold bus' bit if it is greater than FIFO depth. 442 */ 443 if (id->send_count > CDNS_I2C_FIFO_DEPTH) 444 ctrl_reg |= CDNS_I2C_CR_HOLD; 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 acknowedge 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 platform_device *pdev = to_platform_device(dev); 830 struct cdns_i2c *xi2c = platform_get_drvdata(pdev); 831 832 clk_disable(xi2c->clk); 833 834 return 0; 835 } 836 837 /** 838 * cdns_i2c_runtime_resume - Runtime resume 839 * @dev: Address of the platform_device structure 840 * 841 * Runtime resume callback. 842 * 843 * Return: 0 on success and error value on error 844 */ 845 static int __maybe_unused cdns_i2c_runtime_resume(struct device *dev) 846 { 847 struct platform_device *pdev = to_platform_device(dev); 848 struct cdns_i2c *xi2c = platform_get_drvdata(pdev); 849 int ret; 850 851 ret = clk_enable(xi2c->clk); 852 if (ret) { 853 dev_err(dev, "Cannot enable clock.\n"); 854 return ret; 855 } 856 857 return 0; 858 } 859 860 static const struct dev_pm_ops cdns_i2c_dev_pm_ops = { 861 SET_RUNTIME_PM_OPS(cdns_i2c_runtime_suspend, 862 cdns_i2c_runtime_resume, NULL) 863 }; 864 865 static const struct cdns_platform_data r1p10_i2c_def = { 866 .quirks = CDNS_I2C_BROKEN_HOLD_BIT, 867 }; 868 869 static const struct of_device_id cdns_i2c_of_match[] = { 870 { .compatible = "cdns,i2c-r1p10", .data = &r1p10_i2c_def }, 871 { .compatible = "cdns,i2c-r1p14",}, 872 { /* end of table */ } 873 }; 874 MODULE_DEVICE_TABLE(of, cdns_i2c_of_match); 875 876 /** 877 * cdns_i2c_probe - Platform registration call 878 * @pdev: Handle to the platform device structure 879 * 880 * This function does all the memory allocation and registration for the i2c 881 * device. User can modify the address mode to 10 bit address mode using the 882 * ioctl call with option I2C_TENBIT. 883 * 884 * Return: 0 on success, negative error otherwise 885 */ 886 static int cdns_i2c_probe(struct platform_device *pdev) 887 { 888 struct resource *r_mem; 889 struct cdns_i2c *id; 890 int ret; 891 const struct of_device_id *match; 892 893 id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL); 894 if (!id) 895 return -ENOMEM; 896 897 id->dev = &pdev->dev; 898 platform_set_drvdata(pdev, id); 899 900 match = of_match_node(cdns_i2c_of_match, pdev->dev.of_node); 901 if (match && match->data) { 902 const struct cdns_platform_data *data = match->data; 903 id->quirks = data->quirks; 904 } 905 906 r_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 907 id->membase = devm_ioremap_resource(&pdev->dev, r_mem); 908 if (IS_ERR(id->membase)) 909 return PTR_ERR(id->membase); 910 911 id->irq = platform_get_irq(pdev, 0); 912 913 id->adap.owner = THIS_MODULE; 914 id->adap.dev.of_node = pdev->dev.of_node; 915 id->adap.algo = &cdns_i2c_algo; 916 id->adap.timeout = CDNS_I2C_TIMEOUT; 917 id->adap.retries = 3; /* Default retry value. */ 918 id->adap.algo_data = id; 919 id->adap.dev.parent = &pdev->dev; 920 init_completion(&id->xfer_done); 921 snprintf(id->adap.name, sizeof(id->adap.name), 922 "Cadence I2C at %08lx", (unsigned long)r_mem->start); 923 924 id->clk = devm_clk_get(&pdev->dev, NULL); 925 if (IS_ERR(id->clk)) { 926 dev_err(&pdev->dev, "input clock not found.\n"); 927 return PTR_ERR(id->clk); 928 } 929 ret = clk_prepare_enable(id->clk); 930 if (ret) 931 dev_err(&pdev->dev, "Unable to enable clock.\n"); 932 933 pm_runtime_enable(id->dev); 934 pm_runtime_set_autosuspend_delay(id->dev, CNDS_I2C_PM_TIMEOUT); 935 pm_runtime_use_autosuspend(id->dev); 936 pm_runtime_set_active(id->dev); 937 938 id->clk_rate_change_nb.notifier_call = cdns_i2c_clk_notifier_cb; 939 if (clk_notifier_register(id->clk, &id->clk_rate_change_nb)) 940 dev_warn(&pdev->dev, "Unable to register clock notifier.\n"); 941 id->input_clk = clk_get_rate(id->clk); 942 943 ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", 944 &id->i2c_clk); 945 if (ret || (id->i2c_clk > CDNS_I2C_SPEED_MAX)) 946 id->i2c_clk = CDNS_I2C_SPEED_DEFAULT; 947 948 cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS, 949 CDNS_I2C_CR_OFFSET); 950 951 ret = cdns_i2c_setclk(id->input_clk, id); 952 if (ret) { 953 dev_err(&pdev->dev, "invalid SCL clock: %u Hz\n", id->i2c_clk); 954 ret = -EINVAL; 955 goto err_clk_dis; 956 } 957 958 ret = devm_request_irq(&pdev->dev, id->irq, cdns_i2c_isr, 0, 959 DRIVER_NAME, id); 960 if (ret) { 961 dev_err(&pdev->dev, "cannot get irq %d\n", id->irq); 962 goto err_clk_dis; 963 } 964 965 ret = i2c_add_adapter(&id->adap); 966 if (ret < 0) { 967 dev_err(&pdev->dev, "reg adap failed: %d\n", ret); 968 goto err_clk_dis; 969 } 970 971 /* 972 * Cadence I2C controller has a bug wherein it generates 973 * invalid read transaction after HW timeout in master receiver mode. 974 * HW timeout is not used by this driver and the interrupt is disabled. 975 * But the feature itself cannot be disabled. Hence maximum value 976 * is written to this register to reduce the chances of error. 977 */ 978 cdns_i2c_writereg(CDNS_I2C_TIMEOUT_MAX, CDNS_I2C_TIME_OUT_OFFSET); 979 980 dev_info(&pdev->dev, "%u kHz mmio %08lx irq %d\n", 981 id->i2c_clk / 1000, (unsigned long)r_mem->start, id->irq); 982 983 return 0; 984 985 err_clk_dis: 986 clk_disable_unprepare(id->clk); 987 pm_runtime_set_suspended(&pdev->dev); 988 pm_runtime_disable(&pdev->dev); 989 return ret; 990 } 991 992 /** 993 * cdns_i2c_remove - Unregister the device after releasing the resources 994 * @pdev: Handle to the platform device structure 995 * 996 * This function frees all the resources allocated to the device. 997 * 998 * Return: 0 always 999 */ 1000 static int cdns_i2c_remove(struct platform_device *pdev) 1001 { 1002 struct cdns_i2c *id = platform_get_drvdata(pdev); 1003 1004 i2c_del_adapter(&id->adap); 1005 clk_notifier_unregister(id->clk, &id->clk_rate_change_nb); 1006 clk_disable_unprepare(id->clk); 1007 pm_runtime_disable(&pdev->dev); 1008 1009 return 0; 1010 } 1011 1012 static struct platform_driver cdns_i2c_drv = { 1013 .driver = { 1014 .name = DRIVER_NAME, 1015 .of_match_table = cdns_i2c_of_match, 1016 .pm = &cdns_i2c_dev_pm_ops, 1017 }, 1018 .probe = cdns_i2c_probe, 1019 .remove = cdns_i2c_remove, 1020 }; 1021 1022 module_platform_driver(cdns_i2c_drv); 1023 1024 MODULE_AUTHOR("Xilinx Inc."); 1025 MODULE_DESCRIPTION("Cadence I2C bus driver"); 1026 MODULE_LICENSE("GPL"); 1027