1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Driver for STMicroelectronics STM32 I2C controller 4 * 5 * This I2C controller is described in the STM32F429/439 Soc reference manual. 6 * Please see below a link to the documentation: 7 * http://www.st.com/resource/en/reference_manual/DM00031020.pdf 8 * 9 * Copyright (C) M'boumba Cedric Madianga 2016 10 * Copyright (C) STMicroelectronics 2017 11 * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com> 12 * 13 * This driver is based on i2c-st.c 14 * 15 */ 16 17#include <linux/clk.h> 18#include <linux/delay.h> 19#include <linux/err.h> 20#include <linux/i2c.h> 21#include <linux/interrupt.h> 22#include <linux/io.h> 23#include <linux/iopoll.h> 24#include <linux/module.h> 25#include <linux/of_address.h> 26#include <linux/of_irq.h> 27#include <linux/of.h> 28#include <linux/platform_device.h> 29#include <linux/reset.h> 30 31#include "i2c-stm32.h" 32 33/* STM32F4 I2C offset registers */ 34#define STM32F4_I2C_CR1 0x00 35#define STM32F4_I2C_CR2 0x04 36#define STM32F4_I2C_DR 0x10 37#define STM32F4_I2C_SR1 0x14 38#define STM32F4_I2C_SR2 0x18 39#define STM32F4_I2C_CCR 0x1C 40#define STM32F4_I2C_TRISE 0x20 41#define STM32F4_I2C_FLTR 0x24 42 43/* STM32F4 I2C control 1*/ 44#define STM32F4_I2C_CR1_POS BIT(11) 45#define STM32F4_I2C_CR1_ACK BIT(10) 46#define STM32F4_I2C_CR1_STOP BIT(9) 47#define STM32F4_I2C_CR1_START BIT(8) 48#define STM32F4_I2C_CR1_PE BIT(0) 49 50/* STM32F4 I2C control 2 */ 51#define STM32F4_I2C_CR2_FREQ_MASK GENMASK(5, 0) 52#define STM32F4_I2C_CR2_FREQ(n) ((n) & STM32F4_I2C_CR2_FREQ_MASK) 53#define STM32F4_I2C_CR2_ITBUFEN BIT(10) 54#define STM32F4_I2C_CR2_ITEVTEN BIT(9) 55#define STM32F4_I2C_CR2_ITERREN BIT(8) 56#define STM32F4_I2C_CR2_IRQ_MASK (STM32F4_I2C_CR2_ITBUFEN | \ 57 STM32F4_I2C_CR2_ITEVTEN | \ 58 STM32F4_I2C_CR2_ITERREN) 59 60/* STM32F4 I2C Status 1 */ 61#define STM32F4_I2C_SR1_AF BIT(10) 62#define STM32F4_I2C_SR1_ARLO BIT(9) 63#define STM32F4_I2C_SR1_BERR BIT(8) 64#define STM32F4_I2C_SR1_TXE BIT(7) 65#define STM32F4_I2C_SR1_RXNE BIT(6) 66#define STM32F4_I2C_SR1_BTF BIT(2) 67#define STM32F4_I2C_SR1_ADDR BIT(1) 68#define STM32F4_I2C_SR1_SB BIT(0) 69#define STM32F4_I2C_SR1_ITEVTEN_MASK (STM32F4_I2C_SR1_BTF | \ 70 STM32F4_I2C_SR1_ADDR | \ 71 STM32F4_I2C_SR1_SB) 72#define STM32F4_I2C_SR1_ITBUFEN_MASK (STM32F4_I2C_SR1_TXE | \ 73 STM32F4_I2C_SR1_RXNE) 74#define STM32F4_I2C_SR1_ITERREN_MASK (STM32F4_I2C_SR1_AF | \ 75 STM32F4_I2C_SR1_ARLO | \ 76 STM32F4_I2C_SR1_BERR) 77 78/* STM32F4 I2C Status 2 */ 79#define STM32F4_I2C_SR2_BUSY BIT(1) 80 81/* STM32F4 I2C Control Clock */ 82#define STM32F4_I2C_CCR_CCR_MASK GENMASK(11, 0) 83#define STM32F4_I2C_CCR_CCR(n) ((n) & STM32F4_I2C_CCR_CCR_MASK) 84#define STM32F4_I2C_CCR_FS BIT(15) 85#define STM32F4_I2C_CCR_DUTY BIT(14) 86 87/* STM32F4 I2C Trise */ 88#define STM32F4_I2C_TRISE_VALUE_MASK GENMASK(5, 0) 89#define STM32F4_I2C_TRISE_VALUE(n) ((n) & STM32F4_I2C_TRISE_VALUE_MASK) 90 91#define STM32F4_I2C_MIN_STANDARD_FREQ 2U 92#define STM32F4_I2C_MIN_FAST_FREQ 6U 93#define STM32F4_I2C_MAX_FREQ 46U 94#define HZ_TO_MHZ 1000000 95 96/** 97 * struct stm32f4_i2c_msg - client specific data 98 * @addr: 8-bit slave addr, including r/w bit 99 * @count: number of bytes to be transferred 100 * @buf: data buffer 101 * @result: result of the transfer 102 * @stop: last I2C msg to be sent, i.e. STOP to be generated 103 */ 104struct stm32f4_i2c_msg { 105 u8 addr; 106 u32 count; 107 u8 *buf; 108 int result; 109 bool stop; 110}; 111 112/** 113 * struct stm32f4_i2c_dev - private data of the controller 114 * @adap: I2C adapter for this controller 115 * @dev: device for this controller 116 * @base: virtual memory area 117 * @complete: completion of I2C message 118 * @clk: hw i2c clock 119 * @speed: I2C clock frequency of the controller. Standard or Fast are supported 120 * @parent_rate: I2C clock parent rate in MHz 121 * @msg: I2C transfer information 122 */ 123struct stm32f4_i2c_dev { 124 struct i2c_adapter adap; 125 struct device *dev; 126 void __iomem *base; 127 struct completion complete; 128 struct clk *clk; 129 int speed; 130 int parent_rate; 131 struct stm32f4_i2c_msg msg; 132}; 133 134static inline void stm32f4_i2c_set_bits(void __iomem *reg, u32 mask) 135{ 136 writel_relaxed(readl_relaxed(reg) | mask, reg); 137} 138 139static inline void stm32f4_i2c_clr_bits(void __iomem *reg, u32 mask) 140{ 141 writel_relaxed(readl_relaxed(reg) & ~mask, reg); 142} 143 144static void stm32f4_i2c_disable_irq(struct stm32f4_i2c_dev *i2c_dev) 145{ 146 void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2; 147 148 stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_IRQ_MASK); 149} 150 151static int stm32f4_i2c_set_periph_clk_freq(struct stm32f4_i2c_dev *i2c_dev) 152{ 153 u32 freq; 154 u32 cr2 = 0; 155 156 i2c_dev->parent_rate = clk_get_rate(i2c_dev->clk); 157 freq = DIV_ROUND_UP(i2c_dev->parent_rate, HZ_TO_MHZ); 158 159 if (i2c_dev->speed == STM32_I2C_SPEED_STANDARD) { 160 /* 161 * To reach 100 kHz, the parent clk frequency should be between 162 * a minimum value of 2 MHz and a maximum value of 46 MHz due 163 * to hardware limitation 164 */ 165 if (freq < STM32F4_I2C_MIN_STANDARD_FREQ || 166 freq > STM32F4_I2C_MAX_FREQ) { 167 dev_err(i2c_dev->dev, 168 "bad parent clk freq for standard mode\n"); 169 return -EINVAL; 170 } 171 } else { 172 /* 173 * To be as close as possible to 400 kHz, the parent clk 174 * frequency should be between a minimum value of 6 MHz and a 175 * maximum value of 46 MHz due to hardware limitation 176 */ 177 if (freq < STM32F4_I2C_MIN_FAST_FREQ || 178 freq > STM32F4_I2C_MAX_FREQ) { 179 dev_err(i2c_dev->dev, 180 "bad parent clk freq for fast mode\n"); 181 return -EINVAL; 182 } 183 } 184 185 cr2 |= STM32F4_I2C_CR2_FREQ(freq); 186 writel_relaxed(cr2, i2c_dev->base + STM32F4_I2C_CR2); 187 188 return 0; 189} 190 191static void stm32f4_i2c_set_rise_time(struct stm32f4_i2c_dev *i2c_dev) 192{ 193 u32 freq = DIV_ROUND_UP(i2c_dev->parent_rate, HZ_TO_MHZ); 194 u32 trise; 195 196 /* 197 * These bits must be programmed with the maximum SCL rise time given in 198 * the I2C bus specification, incremented by 1. 199 * 200 * In standard mode, the maximum allowed SCL rise time is 1000 ns. 201 * If, in the I2C_CR2 register, the value of FREQ[5:0] bits is equal to 202 * 0x08 so period = 125 ns therefore the TRISE[5:0] bits must be 203 * programmed with 0x9. (1000 ns / 125 ns + 1) 204 * So, for I2C standard mode TRISE = FREQ[5:0] + 1 205 * 206 * In fast mode, the maximum allowed SCL rise time is 300 ns. 207 * If, in the I2C_CR2 register, the value of FREQ[5:0] bits is equal to 208 * 0x08 so period = 125 ns therefore the TRISE[5:0] bits must be 209 * programmed with 0x3. (300 ns / 125 ns + 1) 210 * So, for I2C fast mode TRISE = FREQ[5:0] * 300 / 1000 + 1 211 * 212 * Function stm32f4_i2c_set_periph_clk_freq made sure that parent rate 213 * is not higher than 46 MHz . As a result trise is at most 4 bits wide 214 * and so fits into the TRISE bits [5:0]. 215 */ 216 if (i2c_dev->speed == STM32_I2C_SPEED_STANDARD) 217 trise = freq + 1; 218 else 219 trise = freq * 3 / 10 + 1; 220 221 writel_relaxed(STM32F4_I2C_TRISE_VALUE(trise), 222 i2c_dev->base + STM32F4_I2C_TRISE); 223} 224 225static void stm32f4_i2c_set_speed_mode(struct stm32f4_i2c_dev *i2c_dev) 226{ 227 u32 val; 228 u32 ccr = 0; 229 230 if (i2c_dev->speed == STM32_I2C_SPEED_STANDARD) { 231 /* 232 * In standard mode: 233 * t_scl_high = t_scl_low = CCR * I2C parent clk period 234 * So to reach 100 kHz, we have: 235 * CCR = I2C parent rate / (100 kHz * 2) 236 * 237 * For example with parent rate = 2 MHz: 238 * CCR = 2000000 / (100000 * 2) = 10 239 * t_scl_high = t_scl_low = 10 * (1 / 2000000) = 5000 ns 240 * t_scl_high + t_scl_low = 10000 ns so 100 kHz is reached 241 * 242 * Function stm32f4_i2c_set_periph_clk_freq made sure that 243 * parent rate is not higher than 46 MHz . As a result val 244 * is at most 8 bits wide and so fits into the CCR bits [11:0]. 245 */ 246 val = i2c_dev->parent_rate / (I2C_MAX_STANDARD_MODE_FREQ * 2); 247 } else { 248 /* 249 * In fast mode, we compute CCR with duty = 0 as with low 250 * frequencies we are not able to reach 400 kHz. 251 * In that case: 252 * t_scl_high = CCR * I2C parent clk period 253 * t_scl_low = 2 * CCR * I2C parent clk period 254 * So, CCR = I2C parent rate / (400 kHz * 3) 255 * 256 * For example with parent rate = 6 MHz: 257 * CCR = 6000000 / (400000 * 3) = 5 258 * t_scl_high = 5 * (1 / 6000000) = 833 ns > 600 ns 259 * t_scl_low = 2 * 5 * (1 / 6000000) = 1667 ns > 1300 ns 260 * t_scl_high + t_scl_low = 2500 ns so 400 kHz is reached 261 * 262 * Function stm32f4_i2c_set_periph_clk_freq made sure that 263 * parent rate is not higher than 46 MHz . As a result val 264 * is at most 6 bits wide and so fits into the CCR bits [11:0]. 265 */ 266 val = DIV_ROUND_UP(i2c_dev->parent_rate, I2C_MAX_FAST_MODE_FREQ * 3); 267 268 /* Select Fast mode */ 269 ccr |= STM32F4_I2C_CCR_FS; 270 } 271 272 ccr |= STM32F4_I2C_CCR_CCR(val); 273 writel_relaxed(ccr, i2c_dev->base + STM32F4_I2C_CCR); 274} 275 276/** 277 * stm32f4_i2c_hw_config() - Prepare I2C block 278 * @i2c_dev: Controller's private data 279 */ 280static int stm32f4_i2c_hw_config(struct stm32f4_i2c_dev *i2c_dev) 281{ 282 int ret; 283 284 ret = stm32f4_i2c_set_periph_clk_freq(i2c_dev); 285 if (ret) 286 return ret; 287 288 stm32f4_i2c_set_rise_time(i2c_dev); 289 290 stm32f4_i2c_set_speed_mode(i2c_dev); 291 292 /* Enable I2C */ 293 writel_relaxed(STM32F4_I2C_CR1_PE, i2c_dev->base + STM32F4_I2C_CR1); 294 295 return 0; 296} 297 298static int stm32f4_i2c_wait_free_bus(struct stm32f4_i2c_dev *i2c_dev) 299{ 300 u32 status; 301 int ret; 302 303 ret = readl_relaxed_poll_timeout(i2c_dev->base + STM32F4_I2C_SR2, 304 status, 305 !(status & STM32F4_I2C_SR2_BUSY), 306 10, 1000); 307 if (ret) { 308 dev_dbg(i2c_dev->dev, "bus not free\n"); 309 ret = -EBUSY; 310 } 311 312 return ret; 313} 314 315/** 316 * stm32f4_i2c_write_byte() - Write a byte in the data register 317 * @i2c_dev: Controller's private data 318 * @byte: Data to write in the register 319 */ 320static void stm32f4_i2c_write_byte(struct stm32f4_i2c_dev *i2c_dev, u8 byte) 321{ 322 writel_relaxed(byte, i2c_dev->base + STM32F4_I2C_DR); 323} 324 325/** 326 * stm32f4_i2c_write_msg() - Fill the data register in write mode 327 * @i2c_dev: Controller's private data 328 * 329 * This function fills the data register with I2C transfer buffer 330 */ 331static void stm32f4_i2c_write_msg(struct stm32f4_i2c_dev *i2c_dev) 332{ 333 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 334 335 stm32f4_i2c_write_byte(i2c_dev, *msg->buf++); 336 msg->count--; 337} 338 339static void stm32f4_i2c_read_msg(struct stm32f4_i2c_dev *i2c_dev) 340{ 341 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 342 u32 rbuf; 343 344 rbuf = readl_relaxed(i2c_dev->base + STM32F4_I2C_DR); 345 *msg->buf++ = rbuf; 346 msg->count--; 347} 348 349static void stm32f4_i2c_terminate_xfer(struct stm32f4_i2c_dev *i2c_dev) 350{ 351 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 352 void __iomem *reg; 353 354 stm32f4_i2c_disable_irq(i2c_dev); 355 356 reg = i2c_dev->base + STM32F4_I2C_CR1; 357 if (msg->stop) 358 stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); 359 else 360 stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START); 361 362 complete(&i2c_dev->complete); 363} 364 365/** 366 * stm32f4_i2c_handle_write() - Handle FIFO empty interrupt in case of write 367 * @i2c_dev: Controller's private data 368 */ 369static void stm32f4_i2c_handle_write(struct stm32f4_i2c_dev *i2c_dev) 370{ 371 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 372 void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2; 373 374 if (msg->count) { 375 stm32f4_i2c_write_msg(i2c_dev); 376 if (!msg->count) { 377 /* 378 * Disable buffer interrupts for RX not empty and TX 379 * empty events 380 */ 381 stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_ITBUFEN); 382 } 383 } else { 384 stm32f4_i2c_terminate_xfer(i2c_dev); 385 } 386} 387 388/** 389 * stm32f4_i2c_handle_read() - Handle FIFO empty interrupt in case of read 390 * @i2c_dev: Controller's private data 391 * 392 * This function is called when a new data is received in data register 393 */ 394static void stm32f4_i2c_handle_read(struct stm32f4_i2c_dev *i2c_dev) 395{ 396 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 397 void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2; 398 399 switch (msg->count) { 400 case 1: 401 stm32f4_i2c_disable_irq(i2c_dev); 402 stm32f4_i2c_read_msg(i2c_dev); 403 complete(&i2c_dev->complete); 404 break; 405 /* 406 * For 2-byte reception, 3-byte reception and for Data N-2, N-1 and N 407 * for N-byte reception with N > 3, we do not have to read the data 408 * register when RX not empty event occurs as we have to wait for byte 409 * transferred finished event before reading data. 410 * So, here we just disable buffer interrupt in order to avoid another 411 * system preemption due to RX not empty event. 412 */ 413 case 2: 414 case 3: 415 stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_ITBUFEN); 416 break; 417 /* 418 * For N byte reception with N > 3 we directly read data register 419 * until N-2 data. 420 */ 421 default: 422 stm32f4_i2c_read_msg(i2c_dev); 423 } 424} 425 426/** 427 * stm32f4_i2c_handle_rx_done() - Handle byte transfer finished interrupt 428 * in case of read 429 * @i2c_dev: Controller's private data 430 * 431 * This function is called when a new data is received in the shift register 432 * but data register has not been read yet. 433 */ 434static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev) 435{ 436 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 437 void __iomem *reg; 438 u32 mask; 439 int i; 440 441 switch (msg->count) { 442 case 2: 443 /* 444 * In order to correctly send the Stop or Repeated Start 445 * condition on the I2C bus, the STOP/START bit has to be set 446 * before reading the last two bytes (data N-1 and N). 447 * After that, we could read the last two bytes, disable 448 * remaining interrupts and notify the end of xfer to the 449 * client 450 */ 451 reg = i2c_dev->base + STM32F4_I2C_CR1; 452 if (msg->stop) 453 stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); 454 else 455 stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START); 456 457 for (i = 2; i > 0; i--) 458 stm32f4_i2c_read_msg(i2c_dev); 459 460 reg = i2c_dev->base + STM32F4_I2C_CR2; 461 mask = STM32F4_I2C_CR2_ITEVTEN | STM32F4_I2C_CR2_ITERREN; 462 stm32f4_i2c_clr_bits(reg, mask); 463 464 complete(&i2c_dev->complete); 465 break; 466 case 3: 467 /* 468 * In order to correctly generate the NACK pulse after the last 469 * received data byte, we have to enable NACK before reading N-2 470 * data 471 */ 472 reg = i2c_dev->base + STM32F4_I2C_CR1; 473 stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK); 474 stm32f4_i2c_read_msg(i2c_dev); 475 break; 476 default: 477 stm32f4_i2c_read_msg(i2c_dev); 478 } 479} 480 481/** 482 * stm32f4_i2c_handle_rx_addr() - Handle address matched interrupt in case of 483 * master receiver 484 * @i2c_dev: Controller's private data 485 */ 486static void stm32f4_i2c_handle_rx_addr(struct stm32f4_i2c_dev *i2c_dev) 487{ 488 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 489 u32 cr1; 490 491 switch (msg->count) { 492 case 0: 493 stm32f4_i2c_terminate_xfer(i2c_dev); 494 495 /* Clear ADDR flag */ 496 readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); 497 break; 498 case 1: 499 /* 500 * Single byte reception: 501 * Enable NACK and reset POS (Acknowledge position). 502 * Then, clear ADDR flag and set STOP or RepSTART. 503 * In that way, the NACK and STOP or RepStart pulses will be 504 * sent as soon as the byte will be received in shift register 505 */ 506 cr1 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR1); 507 cr1 &= ~(STM32F4_I2C_CR1_ACK | STM32F4_I2C_CR1_POS); 508 writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); 509 510 readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); 511 512 if (msg->stop) 513 cr1 |= STM32F4_I2C_CR1_STOP; 514 else 515 cr1 |= STM32F4_I2C_CR1_START; 516 writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); 517 break; 518 case 2: 519 /* 520 * 2-byte reception: 521 * Enable NACK, set POS (NACK position) and clear ADDR flag. 522 * In that way, NACK will be sent for the next byte which will 523 * be received in the shift register instead of the current 524 * one. 525 */ 526 cr1 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR1); 527 cr1 &= ~STM32F4_I2C_CR1_ACK; 528 cr1 |= STM32F4_I2C_CR1_POS; 529 writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); 530 531 readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); 532 break; 533 534 default: 535 /* 536 * N-byte reception: 537 * Enable ACK, reset POS (ACK position) and clear ADDR flag. 538 * In that way, ACK will be sent as soon as the current byte 539 * will be received in the shift register 540 */ 541 cr1 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR1); 542 cr1 |= STM32F4_I2C_CR1_ACK; 543 cr1 &= ~STM32F4_I2C_CR1_POS; 544 writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); 545 546 readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); 547 break; 548 } 549} 550 551/** 552 * stm32f4_i2c_isr_event() - Interrupt routine for I2C bus event 553 * @irq: interrupt number 554 * @data: Controller's private data 555 */ 556static irqreturn_t stm32f4_i2c_isr_event(int irq, void *data) 557{ 558 struct stm32f4_i2c_dev *i2c_dev = data; 559 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 560 u32 possible_status = STM32F4_I2C_SR1_ITEVTEN_MASK; 561 u32 status, ien, event, cr2; 562 563 cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2); 564 ien = cr2 & STM32F4_I2C_CR2_IRQ_MASK; 565 566 /* Update possible_status if buffer interrupt is enabled */ 567 if (ien & STM32F4_I2C_CR2_ITBUFEN) 568 possible_status |= STM32F4_I2C_SR1_ITBUFEN_MASK; 569 570 status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1); 571 event = status & possible_status; 572 if (!event) { 573 dev_dbg(i2c_dev->dev, 574 "spurious evt irq (status=0x%08x, ien=0x%08x)\n", 575 status, ien); 576 return IRQ_NONE; 577 } 578 579 /* Start condition generated */ 580 if (event & STM32F4_I2C_SR1_SB) 581 stm32f4_i2c_write_byte(i2c_dev, msg->addr); 582 583 /* I2C Address sent */ 584 if (event & STM32F4_I2C_SR1_ADDR) { 585 if (msg->addr & I2C_M_RD) 586 stm32f4_i2c_handle_rx_addr(i2c_dev); 587 else 588 readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); 589 590 /* 591 * Enable buffer interrupts for RX not empty and TX empty 592 * events 593 */ 594 cr2 |= STM32F4_I2C_CR2_ITBUFEN; 595 writel_relaxed(cr2, i2c_dev->base + STM32F4_I2C_CR2); 596 } 597 598 /* TX empty */ 599 if ((event & STM32F4_I2C_SR1_TXE) && !(msg->addr & I2C_M_RD)) 600 stm32f4_i2c_handle_write(i2c_dev); 601 602 /* RX not empty */ 603 if ((event & STM32F4_I2C_SR1_RXNE) && (msg->addr & I2C_M_RD)) 604 stm32f4_i2c_handle_read(i2c_dev); 605 606 /* 607 * The BTF (Byte Transfer finished) event occurs when: 608 * - in reception : a new byte is received in the shift register 609 * but the previous byte has not been read yet from data register 610 * - in transmission: a new byte should be sent but the data register 611 * has not been written yet 612 */ 613 if (event & STM32F4_I2C_SR1_BTF) { 614 if (msg->addr & I2C_M_RD) 615 stm32f4_i2c_handle_rx_done(i2c_dev); 616 else 617 stm32f4_i2c_handle_write(i2c_dev); 618 } 619 620 return IRQ_HANDLED; 621} 622 623/** 624 * stm32f4_i2c_isr_error() - Interrupt routine for I2C bus error 625 * @irq: interrupt number 626 * @data: Controller's private data 627 */ 628static irqreturn_t stm32f4_i2c_isr_error(int irq, void *data) 629{ 630 struct stm32f4_i2c_dev *i2c_dev = data; 631 struct stm32f4_i2c_msg *msg = &i2c_dev->msg; 632 void __iomem *reg; 633 u32 status; 634 635 status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1); 636 637 /* Arbitration lost */ 638 if (status & STM32F4_I2C_SR1_ARLO) { 639 status &= ~STM32F4_I2C_SR1_ARLO; 640 writel_relaxed(status, i2c_dev->base + STM32F4_I2C_SR1); 641 msg->result = -EAGAIN; 642 } 643 644 /* 645 * Acknowledge failure: 646 * In master transmitter mode a Stop must be generated by software 647 */ 648 if (status & STM32F4_I2C_SR1_AF) { 649 if (!(msg->addr & I2C_M_RD)) { 650 reg = i2c_dev->base + STM32F4_I2C_CR1; 651 stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); 652 } 653 status &= ~STM32F4_I2C_SR1_AF; 654 writel_relaxed(status, i2c_dev->base + STM32F4_I2C_SR1); 655 msg->result = -EIO; 656 } 657 658 /* Bus error */ 659 if (status & STM32F4_I2C_SR1_BERR) { 660 status &= ~STM32F4_I2C_SR1_BERR; 661 writel_relaxed(status, i2c_dev->base + STM32F4_I2C_SR1); 662 msg->result = -EIO; 663 } 664 665 stm32f4_i2c_disable_irq(i2c_dev); 666 complete(&i2c_dev->complete); 667 668 return IRQ_HANDLED; 669} 670 671/** 672 * stm32f4_i2c_xfer_msg() - Transfer a single I2C message 673 * @i2c_dev: Controller's private data 674 * @msg: I2C message to transfer 675 * @is_first: first message of the sequence 676 * @is_last: last message of the sequence 677 */ 678static int stm32f4_i2c_xfer_msg(struct stm32f4_i2c_dev *i2c_dev, 679 struct i2c_msg *msg, bool is_first, 680 bool is_last) 681{ 682 struct stm32f4_i2c_msg *f4_msg = &i2c_dev->msg; 683 void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR1; 684 unsigned long timeout; 685 u32 mask; 686 int ret; 687 688 f4_msg->addr = i2c_8bit_addr_from_msg(msg); 689 f4_msg->buf = msg->buf; 690 f4_msg->count = msg->len; 691 f4_msg->result = 0; 692 f4_msg->stop = is_last; 693 694 reinit_completion(&i2c_dev->complete); 695 696 /* Enable events and errors interrupts */ 697 mask = STM32F4_I2C_CR2_ITEVTEN | STM32F4_I2C_CR2_ITERREN; 698 stm32f4_i2c_set_bits(i2c_dev->base + STM32F4_I2C_CR2, mask); 699 700 if (is_first) { 701 ret = stm32f4_i2c_wait_free_bus(i2c_dev); 702 if (ret) 703 return ret; 704 705 /* START generation */ 706 stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START); 707 } 708 709 timeout = wait_for_completion_timeout(&i2c_dev->complete, 710 i2c_dev->adap.timeout); 711 ret = f4_msg->result; 712 713 if (!timeout) 714 ret = -ETIMEDOUT; 715 716 return ret; 717} 718 719/** 720 * stm32f4_i2c_xfer() - Transfer combined I2C message 721 * @i2c_adap: Adapter pointer to the controller 722 * @msgs: Pointer to data to be written. 723 * @num: Number of messages to be executed 724 */ 725static int stm32f4_i2c_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], 726 int num) 727{ 728 struct stm32f4_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap); 729 int ret, i; 730 731 ret = clk_enable(i2c_dev->clk); 732 if (ret) { 733 dev_err(i2c_dev->dev, "Failed to enable clock\n"); 734 return ret; 735 } 736 737 for (i = 0; i < num && !ret; i++) 738 ret = stm32f4_i2c_xfer_msg(i2c_dev, &msgs[i], i == 0, 739 i == num - 1); 740 741 clk_disable(i2c_dev->clk); 742 743 return (ret < 0) ? ret : num; 744} 745 746static u32 stm32f4_i2c_func(struct i2c_adapter *adap) 747{ 748 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 749} 750 751static const struct i2c_algorithm stm32f4_i2c_algo = { 752 .master_xfer = stm32f4_i2c_xfer, 753 .functionality = stm32f4_i2c_func, 754}; 755 756static int stm32f4_i2c_probe(struct platform_device *pdev) 757{ 758 struct device_node *np = pdev->dev.of_node; 759 struct stm32f4_i2c_dev *i2c_dev; 760 struct resource *res; 761 u32 irq_event, irq_error, clk_rate; 762 struct i2c_adapter *adap; 763 struct reset_control *rst; 764 int ret; 765 766 i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); 767 if (!i2c_dev) 768 return -ENOMEM; 769 770 i2c_dev->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res); 771 if (IS_ERR(i2c_dev->base)) 772 return PTR_ERR(i2c_dev->base); 773 774 irq_event = irq_of_parse_and_map(np, 0); 775 if (!irq_event) { 776 dev_err(&pdev->dev, "IRQ event missing or invalid\n"); 777 return -EINVAL; 778 } 779 780 irq_error = irq_of_parse_and_map(np, 1); 781 if (!irq_error) { 782 dev_err(&pdev->dev, "IRQ error missing or invalid\n"); 783 return -EINVAL; 784 } 785 786 i2c_dev->clk = devm_clk_get_enabled(&pdev->dev, NULL); 787 if (IS_ERR(i2c_dev->clk)) { 788 dev_err(&pdev->dev, "Failed to enable clock\n"); 789 return PTR_ERR(i2c_dev->clk); 790 } 791 792 rst = devm_reset_control_get_exclusive(&pdev->dev, NULL); 793 if (IS_ERR(rst)) 794 return dev_err_probe(&pdev->dev, PTR_ERR(rst), 795 "Error: Missing reset ctrl\n"); 796 797 reset_control_assert(rst); 798 udelay(2); 799 reset_control_deassert(rst); 800 801 i2c_dev->speed = STM32_I2C_SPEED_STANDARD; 802 ret = of_property_read_u32(np, "clock-frequency", &clk_rate); 803 if (!ret && clk_rate >= I2C_MAX_FAST_MODE_FREQ) 804 i2c_dev->speed = STM32_I2C_SPEED_FAST; 805 806 i2c_dev->dev = &pdev->dev; 807 808 ret = devm_request_irq(&pdev->dev, irq_event, stm32f4_i2c_isr_event, 0, 809 pdev->name, i2c_dev); 810 if (ret) { 811 dev_err(&pdev->dev, "Failed to request irq event %i\n", 812 irq_event); 813 return ret; 814 } 815 816 ret = devm_request_irq(&pdev->dev, irq_error, stm32f4_i2c_isr_error, 0, 817 pdev->name, i2c_dev); 818 if (ret) { 819 dev_err(&pdev->dev, "Failed to request irq error %i\n", 820 irq_error); 821 return ret; 822 } 823 824 ret = stm32f4_i2c_hw_config(i2c_dev); 825 if (ret) 826 return ret; 827 828 adap = &i2c_dev->adap; 829 i2c_set_adapdata(adap, i2c_dev); 830 snprintf(adap->name, sizeof(adap->name), "STM32 I2C(%pa)", &res->start); 831 adap->owner = THIS_MODULE; 832 adap->timeout = 2 * HZ; 833 adap->retries = 0; 834 adap->algo = &stm32f4_i2c_algo; 835 adap->dev.parent = &pdev->dev; 836 adap->dev.of_node = pdev->dev.of_node; 837 838 init_completion(&i2c_dev->complete); 839 840 ret = i2c_add_adapter(adap); 841 if (ret) 842 return ret; 843 844 platform_set_drvdata(pdev, i2c_dev); 845 846 clk_disable(i2c_dev->clk); 847 848 dev_info(i2c_dev->dev, "STM32F4 I2C driver registered\n"); 849 850 return 0; 851} 852 853static void stm32f4_i2c_remove(struct platform_device *pdev) 854{ 855 struct stm32f4_i2c_dev *i2c_dev = platform_get_drvdata(pdev); 856 857 i2c_del_adapter(&i2c_dev->adap); 858} 859 860static const struct of_device_id stm32f4_i2c_match[] = { 861 { .compatible = "st,stm32f4-i2c", }, 862 {}, 863}; 864MODULE_DEVICE_TABLE(of, stm32f4_i2c_match); 865 866static struct platform_driver stm32f4_i2c_driver = { 867 .driver = { 868 .name = "stm32f4-i2c", 869 .of_match_table = stm32f4_i2c_match, 870 }, 871 .probe = stm32f4_i2c_probe, 872 .remove_new = stm32f4_i2c_remove, 873}; 874 875module_platform_driver(stm32f4_i2c_driver); 876 877MODULE_AUTHOR("M'boumba Cedric Madianga <cedric.madianga@gmail.com>"); 878MODULE_DESCRIPTION("STMicroelectronics STM32F4 I2C driver"); 879MODULE_LICENSE("GPL v2"); 880