1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * I2C bus driver for the Cadence I2C controller. 4 * 5 * Copyright (C) 2009 - 2014 Xilinx, Inc. 6 */ 7 8 #include <linux/clk.h> 9 #include <linux/delay.h> 10 #include <linux/i2c.h> 11 #include <linux/interrupt.h> 12 #include <linux/io.h> 13 #include <linux/module.h> 14 #include <linux/platform_device.h> 15 #include <linux/of.h> 16 #include <linux/pm_runtime.h> 17 18 /* Register offsets for the I2C device. */ 19 #define CDNS_I2C_CR_OFFSET 0x00 /* Control Register, RW */ 20 #define CDNS_I2C_SR_OFFSET 0x04 /* Status Register, RO */ 21 #define CDNS_I2C_ADDR_OFFSET 0x08 /* I2C Address Register, RW */ 22 #define CDNS_I2C_DATA_OFFSET 0x0C /* I2C Data Register, RW */ 23 #define CDNS_I2C_ISR_OFFSET 0x10 /* IRQ Status Register, RW */ 24 #define CDNS_I2C_XFER_SIZE_OFFSET 0x14 /* Transfer Size Register, RW */ 25 #define CDNS_I2C_TIME_OUT_OFFSET 0x1C /* Time Out Register, RW */ 26 #define CDNS_I2C_IER_OFFSET 0x24 /* IRQ Enable Register, WO */ 27 #define CDNS_I2C_IDR_OFFSET 0x28 /* IRQ Disable Register, WO */ 28 29 /* Control Register Bit mask definitions */ 30 #define CDNS_I2C_CR_HOLD BIT(4) /* Hold Bus bit */ 31 #define CDNS_I2C_CR_ACK_EN BIT(3) 32 #define CDNS_I2C_CR_NEA BIT(2) 33 #define CDNS_I2C_CR_MS BIT(1) 34 /* Read or Write Master transfer 0 = Transmitter, 1 = Receiver */ 35 #define CDNS_I2C_CR_RW BIT(0) 36 /* 1 = Auto init FIFO to zeroes */ 37 #define CDNS_I2C_CR_CLR_FIFO BIT(6) 38 #define CDNS_I2C_CR_DIVA_SHIFT 14 39 #define CDNS_I2C_CR_DIVA_MASK (3 << CDNS_I2C_CR_DIVA_SHIFT) 40 #define CDNS_I2C_CR_DIVB_SHIFT 8 41 #define CDNS_I2C_CR_DIVB_MASK (0x3f << CDNS_I2C_CR_DIVB_SHIFT) 42 43 /* Status Register Bit mask definitions */ 44 #define CDNS_I2C_SR_BA BIT(8) 45 #define CDNS_I2C_SR_RXDV BIT(5) 46 47 /* 48 * I2C Address Register Bit mask definitions 49 * Normal addressing mode uses [6:0] bits. Extended addressing mode uses [9:0] 50 * bits. A write access to this register always initiates a transfer if the I2C 51 * is in master mode. 52 */ 53 #define CDNS_I2C_ADDR_MASK 0x000003FF /* I2C Address Mask */ 54 55 /* 56 * I2C Interrupt Registers Bit mask definitions 57 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same 58 * bit definitions. 59 */ 60 #define CDNS_I2C_IXR_ARB_LOST BIT(9) 61 #define CDNS_I2C_IXR_RX_UNF BIT(7) 62 #define CDNS_I2C_IXR_TX_OVF BIT(6) 63 #define CDNS_I2C_IXR_RX_OVF BIT(5) 64 #define CDNS_I2C_IXR_SLV_RDY BIT(4) 65 #define CDNS_I2C_IXR_TO BIT(3) 66 #define CDNS_I2C_IXR_NACK BIT(2) 67 #define CDNS_I2C_IXR_DATA BIT(1) 68 #define CDNS_I2C_IXR_COMP BIT(0) 69 70 #define CDNS_I2C_IXR_ALL_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ 71 CDNS_I2C_IXR_RX_UNF | \ 72 CDNS_I2C_IXR_TX_OVF | \ 73 CDNS_I2C_IXR_RX_OVF | \ 74 CDNS_I2C_IXR_SLV_RDY | \ 75 CDNS_I2C_IXR_TO | \ 76 CDNS_I2C_IXR_NACK | \ 77 CDNS_I2C_IXR_DATA | \ 78 CDNS_I2C_IXR_COMP) 79 80 #define CDNS_I2C_IXR_ERR_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ 81 CDNS_I2C_IXR_RX_UNF | \ 82 CDNS_I2C_IXR_TX_OVF | \ 83 CDNS_I2C_IXR_RX_OVF | \ 84 CDNS_I2C_IXR_NACK) 85 86 #define CDNS_I2C_ENABLED_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ 87 CDNS_I2C_IXR_RX_UNF | \ 88 CDNS_I2C_IXR_TX_OVF | \ 89 CDNS_I2C_IXR_RX_OVF | \ 90 CDNS_I2C_IXR_NACK | \ 91 CDNS_I2C_IXR_DATA | \ 92 CDNS_I2C_IXR_COMP) 93 94 #define CDNS_I2C_TIMEOUT msecs_to_jiffies(1000) 95 /* timeout for pm runtime autosuspend */ 96 #define CNDS_I2C_PM_TIMEOUT 1000 /* ms */ 97 98 #define CDNS_I2C_FIFO_DEPTH 16 99 /* FIFO depth at which the DATA interrupt occurs */ 100 #define CDNS_I2C_DATA_INTR_DEPTH (CDNS_I2C_FIFO_DEPTH - 2) 101 #define CDNS_I2C_MAX_TRANSFER_SIZE 255 102 /* Transfer size in multiples of data interrupt depth */ 103 #define CDNS_I2C_TRANSFER_SIZE (CDNS_I2C_MAX_TRANSFER_SIZE - 3) 104 105 #define DRIVER_NAME "cdns-i2c" 106 107 #define CDNS_I2C_SPEED_MAX 400000 108 #define CDNS_I2C_SPEED_DEFAULT 100000 109 110 #define CDNS_I2C_DIVA_MAX 4 111 #define CDNS_I2C_DIVB_MAX 64 112 113 #define CDNS_I2C_TIMEOUT_MAX 0xFF 114 115 #define CDNS_I2C_BROKEN_HOLD_BIT BIT(0) 116 117 #define cdns_i2c_readreg(offset) readl_relaxed(id->membase + offset) 118 #define cdns_i2c_writereg(val, offset) writel_relaxed(val, id->membase + offset) 119 120 /** 121 * struct cdns_i2c - I2C device private data structure 122 * 123 * @dev: Pointer to device structure 124 * @membase: Base address of the I2C device 125 * @adap: I2C adapter instance 126 * @p_msg: Message pointer 127 * @err_status: Error status in Interrupt Status Register 128 * @xfer_done: Transfer complete status 129 * @p_send_buf: Pointer to transmit buffer 130 * @p_recv_buf: Pointer to receive buffer 131 * @send_count: Number of bytes still expected to send 132 * @recv_count: Number of bytes still expected to receive 133 * @curr_recv_count: Number of bytes to be received in current transfer 134 * @irq: IRQ number 135 * @input_clk: Input clock to I2C controller 136 * @i2c_clk: Maximum I2C clock speed 137 * @bus_hold_flag: Flag used in repeated start for clearing HOLD bit 138 * @clk: Pointer to struct clk 139 * @clk_rate_change_nb: Notifier block for clock rate changes 140 * @quirks: flag for broken hold bit usage in r1p10 141 */ 142 struct cdns_i2c { 143 struct device *dev; 144 void __iomem *membase; 145 struct i2c_adapter adap; 146 struct i2c_msg *p_msg; 147 int err_status; 148 struct completion xfer_done; 149 unsigned char *p_send_buf; 150 unsigned char *p_recv_buf; 151 unsigned int send_count; 152 unsigned int recv_count; 153 unsigned int curr_recv_count; 154 int irq; 155 unsigned long input_clk; 156 unsigned int i2c_clk; 157 unsigned int bus_hold_flag; 158 struct clk *clk; 159 struct notifier_block clk_rate_change_nb; 160 u32 quirks; 161 }; 162 163 struct cdns_platform_data { 164 u32 quirks; 165 }; 166 167 #define to_cdns_i2c(_nb) container_of(_nb, struct cdns_i2c, \ 168 clk_rate_change_nb) 169 170 /** 171 * cdns_i2c_clear_bus_hold - Clear bus hold bit 172 * @id: Pointer to driver data struct 173 * 174 * Helper to clear the controller's bus hold bit. 175 */ 176 static void cdns_i2c_clear_bus_hold(struct cdns_i2c *id) 177 { 178 u32 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 179 if (reg & CDNS_I2C_CR_HOLD) 180 cdns_i2c_writereg(reg & ~CDNS_I2C_CR_HOLD, CDNS_I2C_CR_OFFSET); 181 } 182 183 static inline bool cdns_is_holdquirk(struct cdns_i2c *id, bool hold_wrkaround) 184 { 185 return (hold_wrkaround && 186 (id->curr_recv_count == CDNS_I2C_FIFO_DEPTH + 1)); 187 } 188 189 /** 190 * cdns_i2c_isr - Interrupt handler for the I2C device 191 * @irq: irq number for the I2C device 192 * @ptr: void pointer to cdns_i2c structure 193 * 194 * This function handles the data interrupt, transfer complete interrupt and 195 * the error interrupts of the I2C device. 196 * 197 * Return: IRQ_HANDLED always 198 */ 199 static irqreturn_t cdns_i2c_isr(int irq, void *ptr) 200 { 201 unsigned int isr_status, avail_bytes, updatetx; 202 unsigned int bytes_to_send; 203 bool hold_quirk; 204 struct cdns_i2c *id = ptr; 205 /* Signal completion only after everything is updated */ 206 int done_flag = 0; 207 irqreturn_t status = IRQ_NONE; 208 209 isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET); 210 cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET); 211 212 /* Handling nack and arbitration lost interrupt */ 213 if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_ARB_LOST)) { 214 done_flag = 1; 215 status = IRQ_HANDLED; 216 } 217 218 /* 219 * Check if transfer size register needs to be updated again for a 220 * large data receive operation. 221 */ 222 updatetx = 0; 223 if (id->recv_count > id->curr_recv_count) 224 updatetx = 1; 225 226 hold_quirk = (id->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx; 227 228 /* When receiving, handle data interrupt and completion interrupt */ 229 if (id->p_recv_buf && 230 ((isr_status & CDNS_I2C_IXR_COMP) || 231 (isr_status & CDNS_I2C_IXR_DATA))) { 232 /* Read data if receive data valid is set */ 233 while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & 234 CDNS_I2C_SR_RXDV) { 235 /* 236 * Clear hold bit that was set for FIFO control if 237 * RX data left is less than FIFO depth, unless 238 * repeated start is selected. 239 */ 240 if ((id->recv_count < CDNS_I2C_FIFO_DEPTH) && 241 !id->bus_hold_flag) 242 cdns_i2c_clear_bus_hold(id); 243 244 *(id->p_recv_buf)++ = 245 cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET); 246 id->recv_count--; 247 id->curr_recv_count--; 248 249 if (cdns_is_holdquirk(id, hold_quirk)) 250 break; 251 } 252 253 /* 254 * The controller sends NACK to the slave when transfer size 255 * register reaches zero without considering the HOLD bit. 256 * This workaround is implemented for large data transfers to 257 * maintain transfer size non-zero while performing a large 258 * receive operation. 259 */ 260 if (cdns_is_holdquirk(id, hold_quirk)) { 261 /* wait while fifo is full */ 262 while (cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET) != 263 (id->curr_recv_count - CDNS_I2C_FIFO_DEPTH)) 264 ; 265 266 /* 267 * Check number of bytes to be received against maximum 268 * transfer size and update register accordingly. 269 */ 270 if (((int)(id->recv_count) - CDNS_I2C_FIFO_DEPTH) > 271 CDNS_I2C_TRANSFER_SIZE) { 272 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE, 273 CDNS_I2C_XFER_SIZE_OFFSET); 274 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE + 275 CDNS_I2C_FIFO_DEPTH; 276 } else { 277 cdns_i2c_writereg(id->recv_count - 278 CDNS_I2C_FIFO_DEPTH, 279 CDNS_I2C_XFER_SIZE_OFFSET); 280 id->curr_recv_count = id->recv_count; 281 } 282 } else if (id->recv_count && !hold_quirk && 283 !id->curr_recv_count) { 284 285 /* Set the slave address in address register*/ 286 cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, 287 CDNS_I2C_ADDR_OFFSET); 288 289 if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) { 290 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE, 291 CDNS_I2C_XFER_SIZE_OFFSET); 292 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE; 293 } else { 294 cdns_i2c_writereg(id->recv_count, 295 CDNS_I2C_XFER_SIZE_OFFSET); 296 id->curr_recv_count = id->recv_count; 297 } 298 } 299 300 /* Clear hold (if not repeated start) and signal completion */ 301 if ((isr_status & CDNS_I2C_IXR_COMP) && !id->recv_count) { 302 if (!id->bus_hold_flag) 303 cdns_i2c_clear_bus_hold(id); 304 done_flag = 1; 305 } 306 307 status = IRQ_HANDLED; 308 } 309 310 /* When sending, handle transfer complete interrupt */ 311 if ((isr_status & CDNS_I2C_IXR_COMP) && !id->p_recv_buf) { 312 /* 313 * If there is more data to be sent, calculate the 314 * space available in FIFO and fill with that many bytes. 315 */ 316 if (id->send_count) { 317 avail_bytes = CDNS_I2C_FIFO_DEPTH - 318 cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET); 319 if (id->send_count > avail_bytes) 320 bytes_to_send = avail_bytes; 321 else 322 bytes_to_send = id->send_count; 323 324 while (bytes_to_send--) { 325 cdns_i2c_writereg( 326 (*(id->p_send_buf)++), 327 CDNS_I2C_DATA_OFFSET); 328 id->send_count--; 329 } 330 } else { 331 /* 332 * Signal the completion of transaction and 333 * clear the hold bus bit if there are no 334 * further messages to be processed. 335 */ 336 done_flag = 1; 337 } 338 if (!id->send_count && !id->bus_hold_flag) 339 cdns_i2c_clear_bus_hold(id); 340 341 status = IRQ_HANDLED; 342 } 343 344 /* Update the status for errors */ 345 id->err_status = isr_status & CDNS_I2C_IXR_ERR_INTR_MASK; 346 if (id->err_status) 347 status = IRQ_HANDLED; 348 349 if (done_flag) 350 complete(&id->xfer_done); 351 352 return status; 353 } 354 355 /** 356 * cdns_i2c_mrecv - Prepare and start a master receive operation 357 * @id: pointer to the i2c device structure 358 */ 359 static void cdns_i2c_mrecv(struct cdns_i2c *id) 360 { 361 unsigned int ctrl_reg; 362 unsigned int isr_status; 363 364 id->p_recv_buf = id->p_msg->buf; 365 id->recv_count = id->p_msg->len; 366 367 /* Put the controller in master receive mode and clear the FIFO */ 368 ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 369 ctrl_reg |= CDNS_I2C_CR_RW | CDNS_I2C_CR_CLR_FIFO; 370 371 if (id->p_msg->flags & I2C_M_RECV_LEN) 372 id->recv_count = I2C_SMBUS_BLOCK_MAX + 1; 373 374 id->curr_recv_count = id->recv_count; 375 376 /* 377 * Check for the message size against FIFO depth and set the 378 * 'hold bus' bit if it is greater than FIFO depth. 379 */ 380 if ((id->recv_count > CDNS_I2C_FIFO_DEPTH) || id->bus_hold_flag) 381 ctrl_reg |= CDNS_I2C_CR_HOLD; 382 else 383 ctrl_reg = ctrl_reg & ~CDNS_I2C_CR_HOLD; 384 385 cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET); 386 387 /* Clear the interrupts in interrupt status register */ 388 isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET); 389 cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET); 390 391 /* 392 * The no. of bytes to receive is checked against the limit of 393 * max transfer size. Set transfer size register with no of bytes 394 * receive if it is less than transfer size and transfer size if 395 * it is more. Enable the interrupts. 396 */ 397 if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) { 398 cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE, 399 CDNS_I2C_XFER_SIZE_OFFSET); 400 id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE; 401 } else { 402 cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET); 403 } 404 405 /* Set the slave address in address register - triggers operation */ 406 cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, 407 CDNS_I2C_ADDR_OFFSET); 408 /* Clear the bus hold flag if bytes to receive is less than FIFO size */ 409 if (!id->bus_hold_flag && 410 ((id->p_msg->flags & I2C_M_RECV_LEN) != I2C_M_RECV_LEN) && 411 (id->recv_count <= CDNS_I2C_FIFO_DEPTH)) 412 cdns_i2c_clear_bus_hold(id); 413 cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET); 414 } 415 416 /** 417 * cdns_i2c_msend - Prepare and start a master send operation 418 * @id: pointer to the i2c device 419 */ 420 static void cdns_i2c_msend(struct cdns_i2c *id) 421 { 422 unsigned int avail_bytes; 423 unsigned int bytes_to_send; 424 unsigned int ctrl_reg; 425 unsigned int isr_status; 426 427 id->p_recv_buf = NULL; 428 id->p_send_buf = id->p_msg->buf; 429 id->send_count = id->p_msg->len; 430 431 /* Set the controller in Master transmit mode and clear the FIFO. */ 432 ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 433 ctrl_reg &= ~CDNS_I2C_CR_RW; 434 ctrl_reg |= CDNS_I2C_CR_CLR_FIFO; 435 436 /* 437 * Check for the message size against FIFO depth and set the 438 * 'hold bus' bit if it is greater than FIFO depth. 439 */ 440 if ((id->send_count > CDNS_I2C_FIFO_DEPTH) || id->bus_hold_flag) 441 ctrl_reg |= CDNS_I2C_CR_HOLD; 442 else 443 ctrl_reg = ctrl_reg & ~CDNS_I2C_CR_HOLD; 444 445 cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET); 446 447 /* Clear the interrupts in interrupt status register. */ 448 isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET); 449 cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET); 450 451 /* 452 * Calculate the space available in FIFO. Check the message length 453 * against the space available, and fill the FIFO accordingly. 454 * Enable the interrupts. 455 */ 456 avail_bytes = CDNS_I2C_FIFO_DEPTH - 457 cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET); 458 459 if (id->send_count > avail_bytes) 460 bytes_to_send = avail_bytes; 461 else 462 bytes_to_send = id->send_count; 463 464 while (bytes_to_send--) { 465 cdns_i2c_writereg((*(id->p_send_buf)++), CDNS_I2C_DATA_OFFSET); 466 id->send_count--; 467 } 468 469 /* 470 * Clear the bus hold flag if there is no more data 471 * and if it is the last message. 472 */ 473 if (!id->bus_hold_flag && !id->send_count) 474 cdns_i2c_clear_bus_hold(id); 475 /* Set the slave address in address register - triggers operation. */ 476 cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, 477 CDNS_I2C_ADDR_OFFSET); 478 479 cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET); 480 } 481 482 /** 483 * cdns_i2c_master_reset - Reset the interface 484 * @adap: pointer to the i2c adapter driver instance 485 * 486 * This function cleanup the fifos, clear the hold bit and status 487 * and disable the interrupts. 488 */ 489 static void cdns_i2c_master_reset(struct i2c_adapter *adap) 490 { 491 struct cdns_i2c *id = adap->algo_data; 492 u32 regval; 493 494 /* Disable the interrupts */ 495 cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET); 496 /* Clear the hold bit and fifos */ 497 regval = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 498 regval &= ~CDNS_I2C_CR_HOLD; 499 regval |= CDNS_I2C_CR_CLR_FIFO; 500 cdns_i2c_writereg(regval, CDNS_I2C_CR_OFFSET); 501 /* Update the transfercount register to zero */ 502 cdns_i2c_writereg(0, CDNS_I2C_XFER_SIZE_OFFSET); 503 /* Clear the interupt status register */ 504 regval = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET); 505 cdns_i2c_writereg(regval, CDNS_I2C_ISR_OFFSET); 506 /* Clear the status register */ 507 regval = cdns_i2c_readreg(CDNS_I2C_SR_OFFSET); 508 cdns_i2c_writereg(regval, CDNS_I2C_SR_OFFSET); 509 } 510 511 static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg, 512 struct i2c_adapter *adap) 513 { 514 unsigned long time_left; 515 u32 reg; 516 517 id->p_msg = msg; 518 id->err_status = 0; 519 reinit_completion(&id->xfer_done); 520 521 /* Check for the TEN Bit mode on each msg */ 522 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 523 if (msg->flags & I2C_M_TEN) { 524 if (reg & CDNS_I2C_CR_NEA) 525 cdns_i2c_writereg(reg & ~CDNS_I2C_CR_NEA, 526 CDNS_I2C_CR_OFFSET); 527 } else { 528 if (!(reg & CDNS_I2C_CR_NEA)) 529 cdns_i2c_writereg(reg | CDNS_I2C_CR_NEA, 530 CDNS_I2C_CR_OFFSET); 531 } 532 533 /* Check for the R/W flag on each msg */ 534 if (msg->flags & I2C_M_RD) 535 cdns_i2c_mrecv(id); 536 else 537 cdns_i2c_msend(id); 538 539 /* Wait for the signal of completion */ 540 time_left = wait_for_completion_timeout(&id->xfer_done, adap->timeout); 541 if (time_left == 0) { 542 cdns_i2c_master_reset(adap); 543 dev_err(id->adap.dev.parent, 544 "timeout waiting on completion\n"); 545 return -ETIMEDOUT; 546 } 547 548 cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, 549 CDNS_I2C_IDR_OFFSET); 550 551 /* If it is bus arbitration error, try again */ 552 if (id->err_status & CDNS_I2C_IXR_ARB_LOST) 553 return -EAGAIN; 554 555 return 0; 556 } 557 558 /** 559 * cdns_i2c_master_xfer - The main i2c transfer function 560 * @adap: pointer to the i2c adapter driver instance 561 * @msgs: pointer to the i2c message structure 562 * @num: the number of messages to transfer 563 * 564 * Initiates the send/recv activity based on the transfer message received. 565 * 566 * Return: number of msgs processed on success, negative error otherwise 567 */ 568 static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, 569 int num) 570 { 571 int ret, count; 572 u32 reg; 573 struct cdns_i2c *id = adap->algo_data; 574 bool hold_quirk; 575 576 ret = pm_runtime_get_sync(id->dev); 577 if (ret < 0) 578 return ret; 579 /* Check if the bus is free */ 580 if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) { 581 ret = -EAGAIN; 582 goto out; 583 } 584 585 hold_quirk = !!(id->quirks & CDNS_I2C_BROKEN_HOLD_BIT); 586 /* 587 * Set the flag to one when multiple messages are to be 588 * processed with a repeated start. 589 */ 590 if (num > 1) { 591 /* 592 * This controller does not give completion interrupt after a 593 * master receive message if HOLD bit is set (repeated start), 594 * resulting in SW timeout. Hence, if a receive message is 595 * followed by any other message, an error is returned 596 * indicating that this sequence is not supported. 597 */ 598 for (count = 0; (count < num - 1 && hold_quirk); count++) { 599 if (msgs[count].flags & I2C_M_RD) { 600 dev_warn(adap->dev.parent, 601 "Can't do repeated start after a receive message\n"); 602 ret = -EOPNOTSUPP; 603 goto out; 604 } 605 } 606 id->bus_hold_flag = 1; 607 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 608 reg |= CDNS_I2C_CR_HOLD; 609 cdns_i2c_writereg(reg, CDNS_I2C_CR_OFFSET); 610 } else { 611 id->bus_hold_flag = 0; 612 } 613 614 /* Process the msg one by one */ 615 for (count = 0; count < num; count++, msgs++) { 616 if (count == (num - 1)) 617 id->bus_hold_flag = 0; 618 619 ret = cdns_i2c_process_msg(id, msgs, adap); 620 if (ret) 621 goto out; 622 623 /* Report the other error interrupts to application */ 624 if (id->err_status) { 625 cdns_i2c_master_reset(adap); 626 627 if (id->err_status & CDNS_I2C_IXR_NACK) { 628 ret = -ENXIO; 629 goto out; 630 } 631 ret = -EIO; 632 goto out; 633 } 634 } 635 636 ret = num; 637 out: 638 pm_runtime_mark_last_busy(id->dev); 639 pm_runtime_put_autosuspend(id->dev); 640 return ret; 641 } 642 643 /** 644 * cdns_i2c_func - Returns the supported features of the I2C driver 645 * @adap: pointer to the i2c adapter structure 646 * 647 * Return: 32 bit value, each bit corresponding to a feature 648 */ 649 static u32 cdns_i2c_func(struct i2c_adapter *adap) 650 { 651 return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | 652 (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) | 653 I2C_FUNC_SMBUS_BLOCK_DATA; 654 } 655 656 static const struct i2c_algorithm cdns_i2c_algo = { 657 .master_xfer = cdns_i2c_master_xfer, 658 .functionality = cdns_i2c_func, 659 }; 660 661 /** 662 * cdns_i2c_calc_divs - Calculate clock dividers 663 * @f: I2C clock frequency 664 * @input_clk: Input clock frequency 665 * @a: First divider (return value) 666 * @b: Second divider (return value) 667 * 668 * f is used as input and output variable. As input it is used as target I2C 669 * frequency. On function exit f holds the actually resulting I2C frequency. 670 * 671 * Return: 0 on success, negative errno otherwise. 672 */ 673 static int cdns_i2c_calc_divs(unsigned long *f, unsigned long input_clk, 674 unsigned int *a, unsigned int *b) 675 { 676 unsigned long fscl = *f, best_fscl = *f, actual_fscl, temp; 677 unsigned int div_a, div_b, calc_div_a = 0, calc_div_b = 0; 678 unsigned int last_error, current_error; 679 680 /* calculate (divisor_a+1) x (divisor_b+1) */ 681 temp = input_clk / (22 * fscl); 682 683 /* 684 * If the calculated value is negative or 0, the fscl input is out of 685 * range. Return error. 686 */ 687 if (!temp || (temp > (CDNS_I2C_DIVA_MAX * CDNS_I2C_DIVB_MAX))) 688 return -EINVAL; 689 690 last_error = -1; 691 for (div_a = 0; div_a < CDNS_I2C_DIVA_MAX; div_a++) { 692 div_b = DIV_ROUND_UP(input_clk, 22 * fscl * (div_a + 1)); 693 694 if ((div_b < 1) || (div_b > CDNS_I2C_DIVB_MAX)) 695 continue; 696 div_b--; 697 698 actual_fscl = input_clk / (22 * (div_a + 1) * (div_b + 1)); 699 700 if (actual_fscl > fscl) 701 continue; 702 703 current_error = ((actual_fscl > fscl) ? (actual_fscl - fscl) : 704 (fscl - actual_fscl)); 705 706 if (last_error > current_error) { 707 calc_div_a = div_a; 708 calc_div_b = div_b; 709 best_fscl = actual_fscl; 710 last_error = current_error; 711 } 712 } 713 714 *a = calc_div_a; 715 *b = calc_div_b; 716 *f = best_fscl; 717 718 return 0; 719 } 720 721 /** 722 * cdns_i2c_setclk - This function sets the serial clock rate for the I2C device 723 * @clk_in: I2C clock input frequency in Hz 724 * @id: Pointer to the I2C device structure 725 * 726 * The device must be idle rather than busy transferring data before setting 727 * these device options. 728 * The data rate is set by values in the control register. 729 * The formula for determining the correct register values is 730 * Fscl = Fpclk/(22 x (divisor_a+1) x (divisor_b+1)) 731 * See the hardware data sheet for a full explanation of setting the serial 732 * clock rate. The clock can not be faster than the input clock divide by 22. 733 * The two most common clock rates are 100KHz and 400KHz. 734 * 735 * Return: 0 on success, negative error otherwise 736 */ 737 static int cdns_i2c_setclk(unsigned long clk_in, struct cdns_i2c *id) 738 { 739 unsigned int div_a, div_b; 740 unsigned int ctrl_reg; 741 int ret = 0; 742 unsigned long fscl = id->i2c_clk; 743 744 ret = cdns_i2c_calc_divs(&fscl, clk_in, &div_a, &div_b); 745 if (ret) 746 return ret; 747 748 ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); 749 ctrl_reg &= ~(CDNS_I2C_CR_DIVA_MASK | CDNS_I2C_CR_DIVB_MASK); 750 ctrl_reg |= ((div_a << CDNS_I2C_CR_DIVA_SHIFT) | 751 (div_b << CDNS_I2C_CR_DIVB_SHIFT)); 752 cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET); 753 754 return 0; 755 } 756 757 /** 758 * cdns_i2c_clk_notifier_cb - Clock rate change callback 759 * @nb: Pointer to notifier block 760 * @event: Notification reason 761 * @data: Pointer to notification data object 762 * 763 * This function is called when the cdns_i2c input clock frequency changes. 764 * The callback checks whether a valid bus frequency can be generated after the 765 * change. If so, the change is acknowledged, otherwise the change is aborted. 766 * New dividers are written to the HW in the pre- or post change notification 767 * depending on the scaling direction. 768 * 769 * Return: NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK 770 * to acknowledge the change, NOTIFY_DONE if the notification is 771 * considered irrelevant. 772 */ 773 static int cdns_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long 774 event, void *data) 775 { 776 struct clk_notifier_data *ndata = data; 777 struct cdns_i2c *id = to_cdns_i2c(nb); 778 779 if (pm_runtime_suspended(id->dev)) 780 return NOTIFY_OK; 781 782 switch (event) { 783 case PRE_RATE_CHANGE: 784 { 785 unsigned long input_clk = ndata->new_rate; 786 unsigned long fscl = id->i2c_clk; 787 unsigned int div_a, div_b; 788 int ret; 789 790 ret = cdns_i2c_calc_divs(&fscl, input_clk, &div_a, &div_b); 791 if (ret) { 792 dev_warn(id->adap.dev.parent, 793 "clock rate change rejected\n"); 794 return NOTIFY_STOP; 795 } 796 797 /* scale up */ 798 if (ndata->new_rate > ndata->old_rate) 799 cdns_i2c_setclk(ndata->new_rate, id); 800 801 return NOTIFY_OK; 802 } 803 case POST_RATE_CHANGE: 804 id->input_clk = ndata->new_rate; 805 /* scale down */ 806 if (ndata->new_rate < ndata->old_rate) 807 cdns_i2c_setclk(ndata->new_rate, id); 808 return NOTIFY_OK; 809 case ABORT_RATE_CHANGE: 810 /* scale up */ 811 if (ndata->new_rate > ndata->old_rate) 812 cdns_i2c_setclk(ndata->old_rate, id); 813 return NOTIFY_OK; 814 default: 815 return NOTIFY_DONE; 816 } 817 } 818 819 /** 820 * cdns_i2c_runtime_suspend - Runtime suspend method for the driver 821 * @dev: Address of the platform_device structure 822 * 823 * Put the driver into low power mode. 824 * 825 * Return: 0 always 826 */ 827 static int __maybe_unused cdns_i2c_runtime_suspend(struct device *dev) 828 { 829 struct cdns_i2c *xi2c = dev_get_drvdata(dev); 830 831 clk_disable(xi2c->clk); 832 833 return 0; 834 } 835 836 /** 837 * cdns_i2c_runtime_resume - Runtime resume 838 * @dev: Address of the platform_device structure 839 * 840 * Runtime resume callback. 841 * 842 * Return: 0 on success and error value on error 843 */ 844 static int __maybe_unused cdns_i2c_runtime_resume(struct device *dev) 845 { 846 struct cdns_i2c *xi2c = dev_get_drvdata(dev); 847 int ret; 848 849 ret = clk_enable(xi2c->clk); 850 if (ret) { 851 dev_err(dev, "Cannot enable clock.\n"); 852 return ret; 853 } 854 855 return 0; 856 } 857 858 static const struct dev_pm_ops cdns_i2c_dev_pm_ops = { 859 SET_RUNTIME_PM_OPS(cdns_i2c_runtime_suspend, 860 cdns_i2c_runtime_resume, NULL) 861 }; 862 863 static const struct cdns_platform_data r1p10_i2c_def = { 864 .quirks = CDNS_I2C_BROKEN_HOLD_BIT, 865 }; 866 867 static const struct of_device_id cdns_i2c_of_match[] = { 868 { .compatible = "cdns,i2c-r1p10", .data = &r1p10_i2c_def }, 869 { .compatible = "cdns,i2c-r1p14",}, 870 { /* end of table */ } 871 }; 872 MODULE_DEVICE_TABLE(of, cdns_i2c_of_match); 873 874 /** 875 * cdns_i2c_probe - Platform registration call 876 * @pdev: Handle to the platform device structure 877 * 878 * This function does all the memory allocation and registration for the i2c 879 * device. User can modify the address mode to 10 bit address mode using the 880 * ioctl call with option I2C_TENBIT. 881 * 882 * Return: 0 on success, negative error otherwise 883 */ 884 static int cdns_i2c_probe(struct platform_device *pdev) 885 { 886 struct resource *r_mem; 887 struct cdns_i2c *id; 888 int ret; 889 const struct of_device_id *match; 890 891 id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL); 892 if (!id) 893 return -ENOMEM; 894 895 id->dev = &pdev->dev; 896 platform_set_drvdata(pdev, id); 897 898 match = of_match_node(cdns_i2c_of_match, pdev->dev.of_node); 899 if (match && match->data) { 900 const struct cdns_platform_data *data = match->data; 901 id->quirks = data->quirks; 902 } 903 904 r_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 905 id->membase = devm_ioremap_resource(&pdev->dev, r_mem); 906 if (IS_ERR(id->membase)) 907 return PTR_ERR(id->membase); 908 909 id->irq = platform_get_irq(pdev, 0); 910 911 id->adap.owner = THIS_MODULE; 912 id->adap.dev.of_node = pdev->dev.of_node; 913 id->adap.algo = &cdns_i2c_algo; 914 id->adap.timeout = CDNS_I2C_TIMEOUT; 915 id->adap.retries = 3; /* Default retry value. */ 916 id->adap.algo_data = id; 917 id->adap.dev.parent = &pdev->dev; 918 init_completion(&id->xfer_done); 919 snprintf(id->adap.name, sizeof(id->adap.name), 920 "Cadence I2C at %08lx", (unsigned long)r_mem->start); 921 922 id->clk = devm_clk_get(&pdev->dev, NULL); 923 if (IS_ERR(id->clk)) { 924 dev_err(&pdev->dev, "input clock not found.\n"); 925 return PTR_ERR(id->clk); 926 } 927 ret = clk_prepare_enable(id->clk); 928 if (ret) 929 dev_err(&pdev->dev, "Unable to enable clock.\n"); 930 931 pm_runtime_enable(id->dev); 932 pm_runtime_set_autosuspend_delay(id->dev, CNDS_I2C_PM_TIMEOUT); 933 pm_runtime_use_autosuspend(id->dev); 934 pm_runtime_set_active(id->dev); 935 936 id->clk_rate_change_nb.notifier_call = cdns_i2c_clk_notifier_cb; 937 if (clk_notifier_register(id->clk, &id->clk_rate_change_nb)) 938 dev_warn(&pdev->dev, "Unable to register clock notifier.\n"); 939 id->input_clk = clk_get_rate(id->clk); 940 941 ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", 942 &id->i2c_clk); 943 if (ret || (id->i2c_clk > CDNS_I2C_SPEED_MAX)) 944 id->i2c_clk = CDNS_I2C_SPEED_DEFAULT; 945 946 cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS, 947 CDNS_I2C_CR_OFFSET); 948 949 ret = cdns_i2c_setclk(id->input_clk, id); 950 if (ret) { 951 dev_err(&pdev->dev, "invalid SCL clock: %u Hz\n", id->i2c_clk); 952 ret = -EINVAL; 953 goto err_clk_dis; 954 } 955 956 ret = devm_request_irq(&pdev->dev, id->irq, cdns_i2c_isr, 0, 957 DRIVER_NAME, id); 958 if (ret) { 959 dev_err(&pdev->dev, "cannot get irq %d\n", id->irq); 960 goto err_clk_dis; 961 } 962 963 /* 964 * Cadence I2C controller has a bug wherein it generates 965 * invalid read transaction after HW timeout in master receiver mode. 966 * HW timeout is not used by this driver and the interrupt is disabled. 967 * But the feature itself cannot be disabled. Hence maximum value 968 * is written to this register to reduce the chances of error. 969 */ 970 cdns_i2c_writereg(CDNS_I2C_TIMEOUT_MAX, CDNS_I2C_TIME_OUT_OFFSET); 971 972 ret = i2c_add_adapter(&id->adap); 973 if (ret < 0) 974 goto err_clk_dis; 975 976 dev_info(&pdev->dev, "%u kHz mmio %08lx irq %d\n", 977 id->i2c_clk / 1000, (unsigned long)r_mem->start, id->irq); 978 979 return 0; 980 981 err_clk_dis: 982 clk_disable_unprepare(id->clk); 983 pm_runtime_set_suspended(&pdev->dev); 984 pm_runtime_disable(&pdev->dev); 985 return ret; 986 } 987 988 /** 989 * cdns_i2c_remove - Unregister the device after releasing the resources 990 * @pdev: Handle to the platform device structure 991 * 992 * This function frees all the resources allocated to the device. 993 * 994 * Return: 0 always 995 */ 996 static int cdns_i2c_remove(struct platform_device *pdev) 997 { 998 struct cdns_i2c *id = platform_get_drvdata(pdev); 999 1000 i2c_del_adapter(&id->adap); 1001 clk_notifier_unregister(id->clk, &id->clk_rate_change_nb); 1002 clk_disable_unprepare(id->clk); 1003 pm_runtime_disable(&pdev->dev); 1004 1005 return 0; 1006 } 1007 1008 static struct platform_driver cdns_i2c_drv = { 1009 .driver = { 1010 .name = DRIVER_NAME, 1011 .of_match_table = cdns_i2c_of_match, 1012 .pm = &cdns_i2c_dev_pm_ops, 1013 }, 1014 .probe = cdns_i2c_probe, 1015 .remove = cdns_i2c_remove, 1016 }; 1017 1018 module_platform_driver(cdns_i2c_drv); 1019 1020 MODULE_AUTHOR("Xilinx Inc."); 1021 MODULE_DESCRIPTION("Cadence I2C bus driver"); 1022 MODULE_LICENSE("GPL"); 1023