drivers/i2c/busses/i2c-stm32f7.c

   1 /*
   2  * Driver for STMicroelectronics STM32F7 I2C controller
   3  *
   4  * This I2C controller is described in the STM32F75xxx and STM32F74xxx Soc
   5  * reference manual.
   6  * Please see below a link to the documentation:
   7  * http://www.st.com/resource/en/reference_manual/dm00124865.pdf
   8  *
   9  * Copyright (C) M'boumba Cedric Madianga 2017
  10  * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
  11  *
  12  * This driver is based on i2c-stm32f4.c
  13  *
  14  * License terms:  GNU General Public License (GPL), version 2
  15  */
  16 #include <linux/clk.h>
  17 #include <linux/delay.h>
  18 #include <linux/err.h>
  19 #include <linux/i2c.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/io.h>
  22 #include <linux/iopoll.h>
  23 #include <linux/module.h>
  24 #include <linux/of.h>
  25 #include <linux/of_address.h>
  26 #include <linux/of_irq.h>
  27 #include <linux/of_platform.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/reset.h>
  30 #include <linux/slab.h>
  31
  32 #include "i2c-stm32.h"
  33
  34 /* STM32F7 I2C registers */
  35 #define STM32F7_I2C_CR1                         0x00
  36 #define STM32F7_I2C_CR2                         0x04
  37 #define STM32F7_I2C_TIMINGR                     0x10
  38 #define STM32F7_I2C_ISR                         0x18
  39 #define STM32F7_I2C_ICR                         0x1C
  40 #define STM32F7_I2C_RXDR                        0x24
  41 #define STM32F7_I2C_TXDR                        0x28
  42
  43 /* STM32F7 I2C control 1 */
  44 #define STM32F7_I2C_CR1_ANFOFF                  BIT(12)
  45 #define STM32F7_I2C_CR1_ERRIE                   BIT(7)
  46 #define STM32F7_I2C_CR1_TCIE                    BIT(6)
  47 #define STM32F7_I2C_CR1_STOPIE                  BIT(5)
  48 #define STM32F7_I2C_CR1_NACKIE                  BIT(4)
  49 #define STM32F7_I2C_CR1_ADDRIE                  BIT(3)
  50 #define STM32F7_I2C_CR1_RXIE                    BIT(2)
  51 #define STM32F7_I2C_CR1_TXIE                    BIT(1)
  52 #define STM32F7_I2C_CR1_PE                      BIT(0)
  53 #define STM32F7_I2C_ALL_IRQ_MASK                (STM32F7_I2C_CR1_ERRIE \
  54                                                 | STM32F7_I2C_CR1_TCIE \
  55                                                 | STM32F7_I2C_CR1_STOPIE \
  56                                                 | STM32F7_I2C_CR1_NACKIE \
  57                                                 | STM32F7_I2C_CR1_RXIE \
  58                                                 | STM32F7_I2C_CR1_TXIE)
  59
  60 /* STM32F7 I2C control 2 */
  61 #define STM32F7_I2C_CR2_RELOAD                  BIT(24)
  62 #define STM32F7_I2C_CR2_NBYTES_MASK             GENMASK(23, 16)
  63 #define STM32F7_I2C_CR2_NBYTES(n)               (((n) & 0xff) << 16)
  64 #define STM32F7_I2C_CR2_NACK                    BIT(15)
  65 #define STM32F7_I2C_CR2_STOP                    BIT(14)
  66 #define STM32F7_I2C_CR2_START                   BIT(13)
  67 #define STM32F7_I2C_CR2_RD_WRN                  BIT(10)
  68 #define STM32F7_I2C_CR2_SADD7_MASK              GENMASK(7, 1)
  69 #define STM32F7_I2C_CR2_SADD7(n)                (((n) & 0x7f) << 1)
  70
  71 /* STM32F7 I2C Interrupt Status */
  72 #define STM32F7_I2C_ISR_BUSY                    BIT(15)
  73 #define STM32F7_I2C_ISR_ARLO                    BIT(9)
  74 #define STM32F7_I2C_ISR_BERR                    BIT(8)
  75 #define STM32F7_I2C_ISR_TCR                     BIT(7)
  76 #define STM32F7_I2C_ISR_TC                      BIT(6)
  77 #define STM32F7_I2C_ISR_STOPF                   BIT(5)
  78 #define STM32F7_I2C_ISR_NACKF                   BIT(4)
  79 #define STM32F7_I2C_ISR_RXNE                    BIT(2)
  80 #define STM32F7_I2C_ISR_TXIS                    BIT(1)
  81
  82 /* STM32F7 I2C Interrupt Clear */
  83 #define STM32F7_I2C_ICR_ARLOCF                  BIT(9)
  84 #define STM32F7_I2C_ICR_BERRCF                  BIT(8)
  85 #define STM32F7_I2C_ICR_STOPCF                  BIT(5)
  86 #define STM32F7_I2C_ICR_NACKCF                  BIT(4)
  87
  88 /* STM32F7 I2C Timing */
  89 #define STM32F7_I2C_TIMINGR_PRESC(n)            (((n) & 0xf) << 28)
  90 #define STM32F7_I2C_TIMINGR_SCLDEL(n)           (((n) & 0xf) << 20)
  91 #define STM32F7_I2C_TIMINGR_SDADEL(n)           (((n) & 0xf) << 16)
  92 #define STM32F7_I2C_TIMINGR_SCLH(n)             (((n) & 0xff) << 8)
  93 #define STM32F7_I2C_TIMINGR_SCLL(n)             ((n) & 0xff)
  94
  95 #define STM32F7_I2C_MAX_LEN                     0xff
  96
  97 #define STM32F7_I2C_DNF_DEFAULT                 0
  98 #define STM32F7_I2C_DNF_MAX                     16
  99
 100 #define STM32F7_I2C_ANALOG_FILTER_ENABLE        1
 101 #define STM32F7_I2C_ANALOG_FILTER_DELAY_MIN     50      /* ns */
 102 #define STM32F7_I2C_ANALOG_FILTER_DELAY_MAX     260     /* ns */
 103
 104 #define STM32F7_I2C_RISE_TIME_DEFAULT           25      /* ns */
 105 #define STM32F7_I2C_FALL_TIME_DEFAULT           10      /* ns */
 106
 107 #define STM32F7_PRESC_MAX                       BIT(4)
 108 #define STM32F7_SCLDEL_MAX                      BIT(4)
 109 #define STM32F7_SDADEL_MAX                      BIT(4)
 110 #define STM32F7_SCLH_MAX                        BIT(8)
 111 #define STM32F7_SCLL_MAX                        BIT(8)
 112
 113 /**
 114  * struct stm32f7_i2c_spec - private i2c specification timing
 115  * @rate: I2C bus speed (Hz)
 116  * @rate_min: 80% of I2C bus speed (Hz)
 117  * @rate_max: 100% of I2C bus speed (Hz)
 118  * @fall_max: Max fall time of both SDA and SCL signals (ns)
 119  * @rise_max: Max rise time of both SDA and SCL signals (ns)
 120  * @hddat_min: Min data hold time (ns)
 121  * @vddat_max: Max data valid time (ns)
 122  * @sudat_min: Min data setup time (ns)
 123  * @l_min: Min low period of the SCL clock (ns)
 124  * @h_min: Min high period of the SCL clock (ns)
 125  */
 126 struct stm32f7_i2c_spec {
 127         u32 rate;
 128         u32 rate_min;
 129         u32 rate_max;
 130         u32 fall_max;
 131         u32 rise_max;
 132         u32 hddat_min;
 133         u32 vddat_max;
 134         u32 sudat_min;
 135         u32 l_min;
 136         u32 h_min;
 137 };
 138
 139 /**
 140  * struct stm32f7_i2c_setup - private I2C timing setup parameters
 141  * @speed: I2C speed mode (standard, Fast Plus)
 142  * @speed_freq: I2C speed frequency  (Hz)
 143  * @clock_src: I2C clock source frequency (Hz)
 144  * @rise_time: Rise time (ns)
 145  * @fall_time: Fall time (ns)
 146  * @dnf: Digital filter coefficient (0-16)
 147  * @analog_filter: Analog filter delay (On/Off)
 148  */
 149 struct stm32f7_i2c_setup {
 150         enum stm32_i2c_speed speed;
 151         u32 speed_freq;
 152         u32 clock_src;
 153         u32 rise_time;
 154         u32 fall_time;
 155         u8 dnf;
 156         bool analog_filter;
 157 };
 158
 159 /**
 160  * struct stm32f7_i2c_timings - private I2C output parameters
 161  * @prec: Prescaler value
 162  * @scldel: Data setup time
 163  * @sdadel: Data hold time
 164  * @sclh: SCL high period (master mode)
 165  * @sclh: SCL low period (master mode)
 166  */
 167 struct stm32f7_i2c_timings {
 168         struct list_head node;
 169         u8 presc;
 170         u8 scldel;
 171         u8 sdadel;
 172         u8 sclh;
 173         u8 scll;
 174 };
 175
 176 /**
 177  * struct stm32f7_i2c_msg - client specific data
 178  * @addr: 8-bit slave addr, including r/w bit
 179  * @count: number of bytes to be transferred
 180  * @buf: data buffer
 181  * @result: result of the transfer
 182  * @stop: last I2C msg to be sent, i.e. STOP to be generated
 183  */
 184 struct stm32f7_i2c_msg {
 185         u8 addr;
 186         u32 count;
 187         u8 *buf;
 188         int result;
 189         bool stop;
 190 };
 191
 192 /**
 193  * struct stm32f7_i2c_dev - private data of the controller
 194  * @adap: I2C adapter for this controller
 195  * @dev: device for this controller
 196  * @base: virtual memory area
 197  * @complete: completion of I2C message
 198  * @clk: hw i2c clock
 199  * @speed: I2C clock frequency of the controller. Standard, Fast or Fast+
 200  * @msg: Pointer to data to be written
 201  * @msg_num: number of I2C messages to be executed
 202  * @msg_id: message identifiant
 203  * @f7_msg: customized i2c msg for driver usage
 204  * @setup: I2C timing input setup
 205  * @timing: I2C computed timings
 206  */
 207 struct stm32f7_i2c_dev {
 208         struct i2c_adapter adap;
 209         struct device *dev;
 210         void __iomem *base;
 211         struct completion complete;
 212         struct clk *clk;
 213         int speed;
 214         struct i2c_msg *msg;
 215         unsigned int msg_num;
 216         unsigned int msg_id;
 217         struct stm32f7_i2c_msg f7_msg;
 218         struct stm32f7_i2c_setup setup;
 219         struct stm32f7_i2c_timings timing;
 220 };
 221
 222 /**
 223  * All these values are coming from I2C Specification, Version 6.0, 4th of
 224  * April 2014.
 225  *
 226  * Table10. Characteristics of the SDA and SCL bus lines for Standard, Fast,
 227  * and Fast-mode Plus I2C-bus devices
 228  */
 229 static struct stm32f7_i2c_spec i2c_specs[] = {
 230         [STM32_I2C_SPEED_STANDARD] = {
 231                 .rate = 100000,
 232                 .rate_min = 80000,
 233                 .rate_max = 100000,
 234                 .fall_max = 300,
 235                 .rise_max = 1000,
 236                 .hddat_min = 0,
 237                 .vddat_max = 3450,
 238                 .sudat_min = 250,
 239                 .l_min = 4700,
 240                 .h_min = 4000,
 241         },
 242         [STM32_I2C_SPEED_FAST] = {
 243                 .rate = 400000,
 244                 .rate_min = 320000,
 245                 .rate_max = 400000,
 246                 .fall_max = 300,
 247                 .rise_max = 300,
 248                 .hddat_min = 0,
 249                 .vddat_max = 900,
 250                 .sudat_min = 100,
 251                 .l_min = 1300,
 252                 .h_min = 600,
 253         },
 254         [STM32_I2C_SPEED_FAST_PLUS] = {
 255                 .rate = 1000000,
 256                 .rate_min = 800000,
 257                 .rate_max = 1000000,
 258                 .fall_max = 100,
 259                 .rise_max = 120,
 260                 .hddat_min = 0,
 261                 .vddat_max = 450,
 262                 .sudat_min = 50,
 263                 .l_min = 500,
 264                 .h_min = 260,
 265         },
 266 };
 267
 268 static const struct stm32f7_i2c_setup stm32f7_setup = {
 269         .rise_time = STM32F7_I2C_RISE_TIME_DEFAULT,
 270         .fall_time = STM32F7_I2C_FALL_TIME_DEFAULT,
 271         .dnf = STM32F7_I2C_DNF_DEFAULT,
 272         .analog_filter = STM32F7_I2C_ANALOG_FILTER_ENABLE,
 273 };
 274
 275 static inline void stm32f7_i2c_set_bits(void __iomem *reg, u32 mask)
 276 {
 277         writel_relaxed(readl_relaxed(reg) | mask, reg);
 278 }
 279
 280 static inline void stm32f7_i2c_clr_bits(void __iomem *reg, u32 mask)
 281 {
 282         writel_relaxed(readl_relaxed(reg) & ~mask, reg);
 283 }
 284
 285 static int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
 286                                       struct stm32f7_i2c_setup *setup,
 287                                       struct stm32f7_i2c_timings *output)
 288 {
 289         u32 p_prev = STM32F7_PRESC_MAX;
 290         u32 i2cclk = DIV_ROUND_CLOSEST(NSEC_PER_SEC,
 291                                        setup->clock_src);
 292         u32 i2cbus = DIV_ROUND_CLOSEST(NSEC_PER_SEC,
 293                                        setup->speed_freq);
 294         u32 clk_error_prev = i2cbus;
 295         u32 tsync;
 296         u32 af_delay_min, af_delay_max;
 297         u32 dnf_delay;
 298         u32 clk_min, clk_max;
 299         int sdadel_min, sdadel_max;
 300         int scldel_min;
 301         struct stm32f7_i2c_timings *v, *_v, *s;
 302         struct list_head solutions;
 303         u16 p, l, a, h;
 304         int ret = 0;
 305
 306         if (setup->speed >= STM32_I2C_SPEED_END) {
 307                 dev_err(i2c_dev->dev, "speed out of bound {%d/%d}\n",
 308                         setup->speed, STM32_I2C_SPEED_END - 1);
 309                 return -EINVAL;
 310         }
 311
 312         if ((setup->rise_time > i2c_specs[setup->speed].rise_max) ||
 313             (setup->fall_time > i2c_specs[setup->speed].fall_max)) {
 314                 dev_err(i2c_dev->dev,
 315                         "timings out of bound Rise{%d>%d}/Fall{%d>%d}\n",
 316                         setup->rise_time, i2c_specs[setup->speed].rise_max,
 317                         setup->fall_time, i2c_specs[setup->speed].fall_max);
 318                 return -EINVAL;
 319         }
 320
 321         if (setup->dnf > STM32F7_I2C_DNF_MAX) {
 322                 dev_err(i2c_dev->dev,
 323                         "DNF out of bound %d/%d\n",
 324                         setup->dnf, STM32F7_I2C_DNF_MAX);
 325                 return -EINVAL;
 326         }
 327
 328         if (setup->speed_freq > i2c_specs[setup->speed].rate) {
 329                 dev_err(i2c_dev->dev, "ERROR: Freq {%d/%d}\n",
 330                         setup->speed_freq, i2c_specs[setup->speed].rate);
 331                 return -EINVAL;
 332         }
 333
 334         /*  Analog and Digital Filters */
 335         af_delay_min =
 336                 (setup->analog_filter ?
 337                  STM32F7_I2C_ANALOG_FILTER_DELAY_MIN : 0);
 338         af_delay_max =
 339                 (setup->analog_filter ?
 340                  STM32F7_I2C_ANALOG_FILTER_DELAY_MAX : 0);
 341         dnf_delay = setup->dnf * i2cclk;
 342
 343         sdadel_min = setup->fall_time - i2c_specs[setup->speed].hddat_min -
 344                 af_delay_min - (setup->dnf + 3) * i2cclk;
 345
 346         sdadel_max = i2c_specs[setup->speed].vddat_max - setup->rise_time -
 347                 af_delay_max - (setup->dnf + 4) * i2cclk;
 348
 349         scldel_min = setup->rise_time + i2c_specs[setup->speed].sudat_min;
 350
 351         if (sdadel_min < 0)
 352                 sdadel_min = 0;
 353         if (sdadel_max < 0)
 354                 sdadel_max = 0;
 355
 356         dev_dbg(i2c_dev->dev, "SDADEL(min/max): %i/%i, SCLDEL(Min): %i\n",
 357                 sdadel_min, sdadel_max, scldel_min);
 358
 359         INIT_LIST_HEAD(&solutions);
 360         /* Compute possible values for PRESC, SCLDEL and SDADEL */
 361         for (p = 0; p < STM32F7_PRESC_MAX; p++) {
 362                 for (l = 0; l < STM32F7_SCLDEL_MAX; l++) {
 363                         u32 scldel = (l + 1) * (p + 1) * i2cclk;
 364
 365                         if (scldel < scldel_min)
 366                                 continue;
 367
 368                         for (a = 0; a < STM32F7_SDADEL_MAX; a++) {
 369                                 u32 sdadel = (a * (p + 1) + 1) * i2cclk;
 370
 371                                 if (((sdadel >= sdadel_min) &&
 372                                      (sdadel <= sdadel_max)) &&
 373                                     (p != p_prev)) {
 374                                         v = kmalloc(sizeof(*v), GFP_KERNEL);
 375                                         if (!v) {
 376                                                 ret = -ENOMEM;
 377                                                 goto exit;
 378                                         }
 379
 380                                         v->presc = p;
 381                                         v->scldel = l;
 382                                         v->sdadel = a;
 383                                         p_prev = p;
 384
 385                                         list_add_tail(&v->node,
 386                                                       &solutions);
 387                                 }
 388                         }
 389                 }
 390         }
 391
 392         if (list_empty(&solutions)) {
 393                 dev_err(i2c_dev->dev, "no Prescaler solution\n");
 394                 ret = -EPERM;
 395                 goto exit;
 396         }
 397
 398         tsync = af_delay_min + dnf_delay + (2 * i2cclk);
 399         s = NULL;
 400         clk_max = NSEC_PER_SEC / i2c_specs[setup->speed].rate_min;
 401         clk_min = NSEC_PER_SEC / i2c_specs[setup->speed].rate_max;
 402
 403         /*
 404          * Among Prescaler possibilities discovered above figures out SCL Low
 405          * and High Period. Provided:
 406          * - SCL Low Period has to be higher than SCL Clock Low Period
 407          *   defined by I2C Specification. I2C Clock has to be lower than
 408          *   (SCL Low Period - Analog/Digital filters) / 4.
 409          * - SCL High Period has to be lower than SCL Clock High Period
 410          *   defined by I2C Specification
 411          * - I2C Clock has to be lower than SCL High Period
 412          */
 413         list_for_each_entry(v, &solutions, node) {
 414                 u32 prescaler = (v->presc + 1) * i2cclk;
 415
 416                 for (l = 0; l < STM32F7_SCLL_MAX; l++) {
 417                         u32 tscl_l = (l + 1) * prescaler + tsync;
 418
 419                         if ((tscl_l < i2c_specs[setup->speed].l_min) ||
 420                             (i2cclk >=
 421                              ((tscl_l - af_delay_min - dnf_delay) / 4))) {
 422                                 continue;
 423                         }
 424
 425                         for (h = 0; h < STM32F7_SCLH_MAX; h++) {
 426                                 u32 tscl_h = (h + 1) * prescaler + tsync;
 427                                 u32 tscl = tscl_l + tscl_h +
 428                                         setup->rise_time + setup->fall_time;
 429
 430                                 if ((tscl >= clk_min) && (tscl <= clk_max) &&
 431                                     (tscl_h >= i2c_specs[setup->speed].h_min) &&
 432                                     (i2cclk < tscl_h)) {
 433                                         int clk_error = tscl - i2cbus;
 434
 435                                         if (clk_error < 0)
 436                                                 clk_error = -clk_error;
 437
 438                                         if (clk_error < clk_error_prev) {
 439                                                 clk_error_prev = clk_error;
 440                                                 v->scll = l;
 441                                                 v->sclh = h;
 442                                                 s = v;
 443                                         }
 444                                 }
 445                         }
 446                 }
 447         }
 448
 449         if (!s) {
 450                 dev_err(i2c_dev->dev, "no solution at all\n");
 451                 ret = -EPERM;
 452                 goto exit;
 453         }
 454
 455         output->presc = s->presc;
 456         output->scldel = s->scldel;
 457         output->sdadel = s->sdadel;
 458         output->scll = s->scll;
 459         output->sclh = s->sclh;
 460
 461         dev_dbg(i2c_dev->dev,
 462                 "Presc: %i, scldel: %i, sdadel: %i, scll: %i, sclh: %i\n",
 463                 output->presc,
 464                 output->scldel, output->sdadel,
 465                 output->scll, output->sclh);
 466
 467 exit:
 468         /* Release list and memory */
 469         list_for_each_entry_safe(v, _v, &solutions, node) {
 470                 list_del(&v->node);
 471                 kfree(v);
 472         }
 473
 474         return ret;
 475 }
 476
 477 static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
 478                                     struct stm32f7_i2c_setup *setup)
 479 {
 480         int ret = 0;
 481
 482         setup->speed = i2c_dev->speed;
 483         setup->speed_freq = i2c_specs[setup->speed].rate;
 484         setup->clock_src = clk_get_rate(i2c_dev->clk);
 485
 486         if (!setup->clock_src) {
 487                 dev_err(i2c_dev->dev, "clock rate is 0\n");
 488                 return -EINVAL;
 489         }
 490
 491         do {
 492                 ret = stm32f7_i2c_compute_timing(i2c_dev, setup,
 493                                                  &i2c_dev->timing);
 494                 if (ret) {
 495                         dev_err(i2c_dev->dev,
 496                                 "failed to compute I2C timings.\n");
 497                         if (i2c_dev->speed > STM32_I2C_SPEED_STANDARD) {
 498                                 i2c_dev->speed--;
 499                                 setup->speed = i2c_dev->speed;
 500                                 setup->speed_freq =
 501                                         i2c_specs[setup->speed].rate;
 502                                 dev_warn(i2c_dev->dev,
 503                                          "downgrade I2C Speed Freq to (%i)\n",
 504                                          i2c_specs[setup->speed].rate);
 505                         } else {
 506                                 break;
 507                         }
 508                 }
 509         } while (ret);
 510
 511         if (ret) {
 512                 dev_err(i2c_dev->dev, "Impossible to compute I2C timings.\n");
 513                 return ret;
 514         }
 515
 516         dev_dbg(i2c_dev->dev, "I2C Speed(%i), Freq(%i), Clk Source(%i)\n",
 517                 setup->speed, setup->speed_freq, setup->clock_src);
 518         dev_dbg(i2c_dev->dev, "I2C Rise(%i) and Fall(%i) Time\n",
 519                 setup->rise_time, setup->fall_time);
 520         dev_dbg(i2c_dev->dev, "I2C Analog Filter(%s), DNF(%i)\n",
 521                 (setup->analog_filter ? "On" : "Off"), setup->dnf);
 522
 523         return 0;
 524 }
 525
 526 static void stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
 527 {
 528         struct stm32f7_i2c_timings *t = &i2c_dev->timing;
 529         u32 timing = 0;
 530
 531         /* Timing settings */
 532         timing |= STM32F7_I2C_TIMINGR_PRESC(t->presc);
 533         timing |= STM32F7_I2C_TIMINGR_SCLDEL(t->scldel);
 534         timing |= STM32F7_I2C_TIMINGR_SDADEL(t->sdadel);
 535         timing |= STM32F7_I2C_TIMINGR_SCLH(t->sclh);
 536         timing |= STM32F7_I2C_TIMINGR_SCLL(t->scll);
 537         writel_relaxed(timing, i2c_dev->base + STM32F7_I2C_TIMINGR);
 538
 539         /* Enable I2C */
 540         if (i2c_dev->setup.analog_filter)
 541                 stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
 542                                      STM32F7_I2C_CR1_ANFOFF);
 543         else
 544                 stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
 545                                      STM32F7_I2C_CR1_ANFOFF);
 546         stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
 547                              STM32F7_I2C_CR1_PE);
 548 }
 549
 550 static void stm32f7_i2c_write_tx_data(struct stm32f7_i2c_dev *i2c_dev)
 551 {
 552         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 553         void __iomem *base = i2c_dev->base;
 554
 555         if (f7_msg->count) {
 556                 writeb_relaxed(*f7_msg->buf++, base + STM32F7_I2C_TXDR);
 557                 f7_msg->count--;
 558         }
 559 }
 560
 561 static void stm32f7_i2c_read_rx_data(struct stm32f7_i2c_dev *i2c_dev)
 562 {
 563         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 564         void __iomem *base = i2c_dev->base;
 565
 566         if (f7_msg->count) {
 567                 *f7_msg->buf++ = readb_relaxed(base + STM32F7_I2C_RXDR);
 568                 f7_msg->count--;
 569         }
 570 }
 571
 572 static void stm32f7_i2c_reload(struct stm32f7_i2c_dev *i2c_dev)
 573 {
 574         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 575         u32 cr2;
 576
 577         cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
 578
 579         cr2 &= ~STM32F7_I2C_CR2_NBYTES_MASK;
 580         if (f7_msg->count > STM32F7_I2C_MAX_LEN) {
 581                 cr2 |= STM32F7_I2C_CR2_NBYTES(STM32F7_I2C_MAX_LEN);
 582         } else {
 583                 cr2 &= ~STM32F7_I2C_CR2_RELOAD;
 584                 cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
 585         }
 586
 587         writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
 588 }
 589
 590 static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
 591 {
 592         u32 status;
 593         int ret;
 594
 595         ret = readl_relaxed_poll_timeout(i2c_dev->base + STM32F7_I2C_ISR,
 596                                          status,
 597                                          !(status & STM32F7_I2C_ISR_BUSY),
 598                                          10, 1000);
 599         if (ret) {
 600                 dev_dbg(i2c_dev->dev, "bus busy\n");
 601                 ret = -EBUSY;
 602         }
 603
 604         return ret;
 605 }
 606
 607 static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 608                                  struct i2c_msg *msg)
 609 {
 610         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 611         void __iomem *base = i2c_dev->base;
 612         u32 cr1, cr2;
 613
 614         f7_msg->addr = msg->addr;
 615         f7_msg->buf = msg->buf;
 616         f7_msg->count = msg->len;
 617         f7_msg->result = 0;
 618         f7_msg->stop = (i2c_dev->msg_id >= i2c_dev->msg_num - 1);
 619
 620         reinit_completion(&i2c_dev->complete);
 621
 622         cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
 623         cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
 624
 625         /* Set transfer direction */
 626         cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
 627         if (msg->flags & I2C_M_RD)
 628                 cr2 |= STM32F7_I2C_CR2_RD_WRN;
 629
 630         /* Set slave address */
 631         cr2 &= ~STM32F7_I2C_CR2_SADD7_MASK;
 632         cr2 |= STM32F7_I2C_CR2_SADD7(f7_msg->addr);
 633
 634         /* Set nb bytes to transfer and reload if needed */
 635         cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK | STM32F7_I2C_CR2_RELOAD);
 636         if (f7_msg->count > STM32F7_I2C_MAX_LEN) {
 637                 cr2 |= STM32F7_I2C_CR2_NBYTES(STM32F7_I2C_MAX_LEN);
 638                 cr2 |= STM32F7_I2C_CR2_RELOAD;
 639         } else {
 640                 cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
 641         }
 642
 643         /* Enable NACK, STOP, error and transfer complete interrupts */
 644         cr1 |= STM32F7_I2C_CR1_ERRIE | STM32F7_I2C_CR1_TCIE |
 645                 STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE;
 646
 647         /* Clear TX/RX interrupt */
 648         cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
 649
 650         /* Enable RX/TX interrupt according to msg direction */
 651         if (msg->flags & I2C_M_RD)
 652                 cr1 |= STM32F7_I2C_CR1_RXIE;
 653         else
 654                 cr1 |= STM32F7_I2C_CR1_TXIE;
 655
 656         /* Configure Start/Repeated Start */
 657         cr2 |= STM32F7_I2C_CR2_START;
 658
 659         /* Write configurations registers */
 660         writel_relaxed(cr1, base + STM32F7_I2C_CR1);
 661         writel_relaxed(cr2, base + STM32F7_I2C_CR2);
 662 }
 663
 664 static void stm32f7_i2c_disable_irq(struct stm32f7_i2c_dev *i2c_dev, u32 mask)
 665 {
 666         stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1, mask);
 667 }
 668
 669 static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 670 {
 671         struct stm32f7_i2c_dev *i2c_dev = data;
 672         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 673         void __iomem *base = i2c_dev->base;
 674         u32 status, mask;
 675
 676         status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
 677
 678         /* Tx empty */
 679         if (status & STM32F7_I2C_ISR_TXIS)
 680                 stm32f7_i2c_write_tx_data(i2c_dev);
 681
 682         /* RX not empty */
 683         if (status & STM32F7_I2C_ISR_RXNE)
 684                 stm32f7_i2c_read_rx_data(i2c_dev);
 685
 686         /* NACK received */
 687         if (status & STM32F7_I2C_ISR_NACKF) {
 688                 dev_dbg(i2c_dev->dev, "<%s>: Receive NACK\n", __func__);
 689                 writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
 690                 f7_msg->result = -ENXIO;
 691         }
 692
 693         /* STOP detection flag */
 694         if (status & STM32F7_I2C_ISR_STOPF) {
 695                 /* Disable interrupts */
 696                 stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
 697
 698                 /* Clear STOP flag */
 699                 writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
 700
 701                 complete(&i2c_dev->complete);
 702         }
 703
 704         /* Transfer complete */
 705         if (status & STM32F7_I2C_ISR_TC) {
 706                 if (f7_msg->stop) {
 707                         mask = STM32F7_I2C_CR2_STOP;
 708                         stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
 709                 } else {
 710                         i2c_dev->msg_id++;
 711                         i2c_dev->msg++;
 712                         stm32f7_i2c_xfer_msg(i2c_dev, i2c_dev->msg);
 713                 }
 714         }
 715
 716         /*
 717          * Transfer Complete Reload: 255 data bytes have been transferred
 718          * We have to prepare the I2C controller to transfer the remaining
 719          * data.
 720          */
 721         if (status & STM32F7_I2C_ISR_TCR)
 722                 stm32f7_i2c_reload(i2c_dev);
 723
 724         return IRQ_HANDLED;
 725 }
 726
 727 static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
 728 {
 729         struct stm32f7_i2c_dev *i2c_dev = data;
 730         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 731         void __iomem *base = i2c_dev->base;
 732         struct device *dev = i2c_dev->dev;
 733         u32 status;
 734
 735         status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
 736
 737         /* Bus error */
 738         if (status & STM32F7_I2C_ISR_BERR) {
 739                 dev_err(dev, "<%s>: Bus error\n", __func__);
 740                 writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
 741                 f7_msg->result = -EIO;
 742         }
 743
 744         /* Arbitration loss */
 745         if (status & STM32F7_I2C_ISR_ARLO) {
 746                 dev_dbg(dev, "<%s>: Arbitration loss\n", __func__);
 747                 writel_relaxed(STM32F7_I2C_ICR_ARLOCF, base + STM32F7_I2C_ICR);
 748                 f7_msg->result = -EAGAIN;
 749         }
 750
 751         stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
 752
 753         complete(&i2c_dev->complete);
 754
 755         return IRQ_HANDLED;
 756 }
 757
 758 static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 759                             struct i2c_msg msgs[], int num)
 760 {
 761         struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
 762         struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 763         unsigned long time_left;
 764         int ret;
 765
 766         i2c_dev->msg = msgs;
 767         i2c_dev->msg_num = num;
 768         i2c_dev->msg_id = 0;
 769
 770         ret = clk_enable(i2c_dev->clk);
 771         if (ret) {
 772                 dev_err(i2c_dev->dev, "Failed to enable clock\n");
 773                 return ret;
 774         }
 775
 776         ret = stm32f7_i2c_wait_free_bus(i2c_dev);
 777         if (ret)
 778                 goto clk_free;
 779
 780         stm32f7_i2c_xfer_msg(i2c_dev, msgs);
 781
 782         time_left = wait_for_completion_timeout(&i2c_dev->complete,
 783                                                 i2c_dev->adap.timeout);
 784         ret = f7_msg->result;
 785
 786         if (!time_left) {
 787                 dev_dbg(i2c_dev->dev, "Access to slave 0x%x timed out\n",
 788                         i2c_dev->msg->addr);
 789                 ret = -ETIMEDOUT;
 790         }
 791
 792 clk_free:
 793         clk_disable(i2c_dev->clk);
 794
 795         return (ret < 0) ? ret : num;
 796 }
 797
 798 static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
 799 {
 800         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 801 }
 802
 803 static struct i2c_algorithm stm32f7_i2c_algo = {
 804         .master_xfer = stm32f7_i2c_xfer,
 805         .functionality = stm32f7_i2c_func,
 806 };
 807
 808 static int stm32f7_i2c_probe(struct platform_device *pdev)
 809 {
 810         struct device_node *np = pdev->dev.of_node;
 811         struct stm32f7_i2c_dev *i2c_dev;
 812         const struct stm32f7_i2c_setup *setup;
 813         struct resource *res;
 814         u32 irq_error, irq_event, clk_rate, rise_time, fall_time;
 815         struct i2c_adapter *adap;
 816         struct reset_control *rst;
 817         int ret;
 818
 819         i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
 820         if (!i2c_dev)
 821                 return -ENOMEM;
 822
 823         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 824         i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
 825         if (IS_ERR(i2c_dev->base))
 826                 return PTR_ERR(i2c_dev->base);
 827
 828         irq_event = irq_of_parse_and_map(np, 0);
 829         if (!irq_event) {
 830                 dev_err(&pdev->dev, "IRQ event missing or invalid\n");
 831                 return -EINVAL;
 832         }
 833
 834         irq_error = irq_of_parse_and_map(np, 1);
 835         if (!irq_error) {
 836                 dev_err(&pdev->dev, "IRQ error missing or invalid\n");
 837                 return -EINVAL;
 838         }
 839
 840         i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
 841         if (IS_ERR(i2c_dev->clk)) {
 842                 dev_err(&pdev->dev, "Error: Missing controller clock\n");
 843                 return PTR_ERR(i2c_dev->clk);
 844         }
 845         ret = clk_prepare_enable(i2c_dev->clk);
 846         if (ret) {
 847                 dev_err(&pdev->dev, "Failed to prepare_enable clock\n");
 848                 return ret;
 849         }
 850
 851         i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
 852         ret = device_property_read_u32(&pdev->dev, "clock-frequency",
 853                                        &clk_rate);
 854         if (!ret && clk_rate >= 1000000)
 855                 i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
 856         else if (!ret && clk_rate >= 400000)
 857                 i2c_dev->speed = STM32_I2C_SPEED_FAST;
 858         else if (!ret && clk_rate >= 100000)
 859                 i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
 860
 861         rst = devm_reset_control_get(&pdev->dev, NULL);
 862         if (IS_ERR(rst)) {
 863                 dev_err(&pdev->dev, "Error: Missing controller reset\n");
 864                 ret = PTR_ERR(rst);
 865                 goto clk_free;
 866         }
 867         reset_control_assert(rst);
 868         udelay(2);
 869         reset_control_deassert(rst);
 870
 871         i2c_dev->dev = &pdev->dev;
 872
 873         ret = devm_request_irq(&pdev->dev, irq_event, stm32f7_i2c_isr_event, 0,
 874                                pdev->name, i2c_dev);
 875         if (ret) {
 876                 dev_err(&pdev->dev, "Failed to request irq event %i\n",
 877                         irq_event);
 878                 goto clk_free;
 879         }
 880
 881         ret = devm_request_irq(&pdev->dev, irq_error, stm32f7_i2c_isr_error, 0,
 882                                pdev->name, i2c_dev);
 883         if (ret) {
 884                 dev_err(&pdev->dev, "Failed to request irq error %i\n",
 885                         irq_error);
 886                 goto clk_free;
 887         }
 888
 889         setup = of_device_get_match_data(&pdev->dev);
 890         i2c_dev->setup = *setup;
 891
 892         ret = device_property_read_u32(i2c_dev->dev, "i2c-scl-rising-time-ns",
 893                                        &rise_time);
 894         if (!ret)
 895                 i2c_dev->setup.rise_time = rise_time;
 896
 897         ret = device_property_read_u32(i2c_dev->dev, "i2c-scl-falling-time-ns",
 898                                        &fall_time);
 899         if (!ret)
 900                 i2c_dev->setup.fall_time = fall_time;
 901
 902         ret = stm32f7_i2c_setup_timing(i2c_dev, &i2c_dev->setup);
 903         if (ret)
 904                 goto clk_free;
 905
 906         stm32f7_i2c_hw_config(i2c_dev);
 907
 908         adap = &i2c_dev->adap;
 909         i2c_set_adapdata(adap, i2c_dev);
 910         snprintf(adap->name, sizeof(adap->name), "STM32F7 I2C(%pa)",
 911                  &res->start);
 912         adap->owner = THIS_MODULE;
 913         adap->timeout = 2 * HZ;
 914         adap->retries = 3;
 915         adap->algo = &stm32f7_i2c_algo;
 916         adap->dev.parent = &pdev->dev;
 917         adap->dev.of_node = pdev->dev.of_node;
 918
 919         init_completion(&i2c_dev->complete);
 920
 921         ret = i2c_add_adapter(adap);
 922         if (ret)
 923                 goto clk_free;
 924
 925         platform_set_drvdata(pdev, i2c_dev);
 926
 927         clk_disable(i2c_dev->clk);
 928
 929         dev_info(i2c_dev->dev, "STM32F7 I2C-%d bus adapter\n", adap->nr);
 930
 931         return 0;
 932
 933 clk_free:
 934         clk_disable_unprepare(i2c_dev->clk);
 935
 936         return ret;
 937 }
 938
 939 static int stm32f7_i2c_remove(struct platform_device *pdev)
 940 {
 941         struct stm32f7_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
 942
 943         i2c_del_adapter(&i2c_dev->adap);
 944
 945         clk_unprepare(i2c_dev->clk);
 946
 947         return 0;
 948 }
 949
 950 static const struct of_device_id stm32f7_i2c_match[] = {
 951         { .compatible = "st,stm32f7-i2c", .data = &stm32f7_setup},
 952         {},
 953 };
 954 MODULE_DEVICE_TABLE(of, stm32f7_i2c_match);
 955
 956 static struct platform_driver stm32f7_i2c_driver = {
 957         .driver = {
 958                 .name = "stm32f7-i2c",
 959                 .of_match_table = stm32f7_i2c_match,
 960         },
 961         .probe = stm32f7_i2c_probe,
 962         .remove = stm32f7_i2c_remove,
 963 };
 964
 965 module_platform_driver(stm32f7_i2c_driver);
 966
 967 MODULE_AUTHOR("M'boumba Cedric Madianga <cedric.madianga@gmail.com>");
 968 MODULE_DESCRIPTION("STMicroelectronics STM32F7 I2C driver");
 969 MODULE_LICENSE("GPL v2");