drivers/i2c/stm32f7_i2c.c

   1 /*
   2  * (C) Copyright 2017 STMicroelectronics
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <clk.h>
   9 #include <dm.h>
  10 #include <i2c.h>
  11 #include <reset.h>
  12
  13 #include <dm/device.h>
  14 #include <linux/io.h>
  15
  16 /* STM32 I2C registers */
  17 struct stm32_i2c_regs {
  18         u32 cr1;        /* I2C control register 1 */
  19         u32 cr2;        /* I2C control register 2 */
  20         u32 oar1;       /* I2C own address 1 register */
  21         u32 oar2;       /* I2C own address 2 register */
  22         u32 timingr;    /* I2C timing register */
  23         u32 timeoutr;   /* I2C timeout register */
  24         u32 isr;        /* I2C interrupt and status register */
  25         u32 icr;        /* I2C interrupt clear register */
  26         u32 pecr;       /* I2C packet error checking register */
  27         u32 rxdr;       /* I2C receive data register */
  28         u32 txdr;       /* I2C transmit data register */
  29 };
  30
  31 #define STM32_I2C_CR1                           0x00
  32 #define STM32_I2C_CR2                           0x04
  33 #define STM32_I2C_TIMINGR                       0x10
  34 #define STM32_I2C_ISR                           0x18
  35 #define STM32_I2C_ICR                           0x1C
  36 #define STM32_I2C_RXDR                          0x24
  37 #define STM32_I2C_TXDR                          0x28
  38
  39 /* STM32 I2C control 1 */
  40 #define STM32_I2C_CR1_ANFOFF                    BIT(12)
  41 #define STM32_I2C_CR1_ERRIE                     BIT(7)
  42 #define STM32_I2C_CR1_TCIE                      BIT(6)
  43 #define STM32_I2C_CR1_STOPIE                    BIT(5)
  44 #define STM32_I2C_CR1_NACKIE                    BIT(4)
  45 #define STM32_I2C_CR1_ADDRIE                    BIT(3)
  46 #define STM32_I2C_CR1_RXIE                      BIT(2)
  47 #define STM32_I2C_CR1_TXIE                      BIT(1)
  48 #define STM32_I2C_CR1_PE                        BIT(0)
  49
  50 /* STM32 I2C control 2 */
  51 #define STM32_I2C_CR2_AUTOEND                   BIT(25)
  52 #define STM32_I2C_CR2_RELOAD                    BIT(24)
  53 #define STM32_I2C_CR2_NBYTES_MASK               GENMASK(23, 16)
  54 #define STM32_I2C_CR2_NBYTES(n)                 ((n & 0xff) << 16)
  55 #define STM32_I2C_CR2_NACK                      BIT(15)
  56 #define STM32_I2C_CR2_STOP                      BIT(14)
  57 #define STM32_I2C_CR2_START                     BIT(13)
  58 #define STM32_I2C_CR2_HEAD10R                   BIT(12)
  59 #define STM32_I2C_CR2_ADD10                     BIT(11)
  60 #define STM32_I2C_CR2_RD_WRN                    BIT(10)
  61 #define STM32_I2C_CR2_SADD10_MASK               GENMASK(9, 0)
  62 #define STM32_I2C_CR2_SADD10(n)                 ((n & STM32_I2C_CR2_SADD10_MASK))
  63 #define STM32_I2C_CR2_SADD7_MASK                GENMASK(7, 1)
  64 #define STM32_I2C_CR2_SADD7(n)                  ((n & 0x7f) << 1)
  65 #define STM32_I2C_CR2_RESET_MASK                (STM32_I2C_CR2_HEAD10R \
  66                                                 | STM32_I2C_CR2_NBYTES_MASK \
  67                                                 | STM32_I2C_CR2_SADD7_MASK \
  68                                                 | STM32_I2C_CR2_RELOAD \
  69                                                 | STM32_I2C_CR2_RD_WRN)
  70
  71 /* STM32 I2C Interrupt Status */
  72 #define STM32_I2C_ISR_BUSY                      BIT(15)
  73 #define STM32_I2C_ISR_ARLO                      BIT(9)
  74 #define STM32_I2C_ISR_BERR                      BIT(8)
  75 #define STM32_I2C_ISR_TCR                       BIT(7)
  76 #define STM32_I2C_ISR_TC                        BIT(6)
  77 #define STM32_I2C_ISR_STOPF                     BIT(5)
  78 #define STM32_I2C_ISR_NACKF                     BIT(4)
  79 #define STM32_I2C_ISR_ADDR                      BIT(3)
  80 #define STM32_I2C_ISR_RXNE                      BIT(2)
  81 #define STM32_I2C_ISR_TXIS                      BIT(1)
  82 #define STM32_I2C_ISR_TXE                       BIT(0)
  83 #define STM32_I2C_ISR_ERRORS                    (STM32_I2C_ISR_BERR \
  84                                                 | STM32_I2C_ISR_ARLO)
  85
  86 /* STM32 I2C Interrupt Clear */
  87 #define STM32_I2C_ICR_ARLOCF                    BIT(9)
  88 #define STM32_I2C_ICR_BERRCF                    BIT(8)
  89 #define STM32_I2C_ICR_STOPCF                    BIT(5)
  90 #define STM32_I2C_ICR_NACKCF                    BIT(4)
  91
  92 /* STM32 I2C Timing */
  93 #define STM32_I2C_TIMINGR_PRESC(n)              ((n & 0xf) << 28)
  94 #define STM32_I2C_TIMINGR_SCLDEL(n)             ((n & 0xf) << 20)
  95 #define STM32_I2C_TIMINGR_SDADEL(n)             ((n & 0xf) << 16)
  96 #define STM32_I2C_TIMINGR_SCLH(n)               ((n & 0xff) << 8)
  97 #define STM32_I2C_TIMINGR_SCLL(n)               (n & 0xff)
  98
  99 #define STM32_I2C_MAX_LEN                       0xff
 100
 101 #define STM32_I2C_DNF_DEFAULT                   0
 102 #define STM32_I2C_DNF_MAX                       16
 103
 104 #define STM32_I2C_ANALOG_FILTER_ENABLE  1
 105 #define STM32_I2C_ANALOG_FILTER_DELAY_MIN       50      /* ns */
 106 #define STM32_I2C_ANALOG_FILTER_DELAY_MAX       260     /* ns */
 107
 108 #define STM32_I2C_RISE_TIME_DEFAULT             25      /* ns */
 109 #define STM32_I2C_FALL_TIME_DEFAULT             10      /* ns */
 110
 111 #define STM32_PRESC_MAX                         BIT(4)
 112 #define STM32_SCLDEL_MAX                        BIT(4)
 113 #define STM32_SDADEL_MAX                        BIT(4)
 114 #define STM32_SCLH_MAX                          BIT(8)
 115 #define STM32_SCLL_MAX                          BIT(8)
 116
 117 #define STM32_NSEC_PER_SEC                      1000000000L
 118
 119 #define STANDARD_RATE                           100000
 120 #define FAST_RATE                               400000
 121 #define FAST_PLUS_RATE                          1000000
 122
 123 enum stm32_i2c_speed {
 124         STM32_I2C_SPEED_STANDARD, /* 100 kHz */
 125         STM32_I2C_SPEED_FAST, /* 400 kHz */
 126         STM32_I2C_SPEED_FAST_PLUS, /* 1 MHz */
 127         STM32_I2C_SPEED_END,
 128 };
 129
 130 /**
 131  * struct stm32_i2c_spec - private i2c specification timing
 132  * @rate: I2C bus speed (Hz)
 133  * @rate_min: 80% of I2C bus speed (Hz)
 134  * @rate_max: 120% of I2C bus speed (Hz)
 135  * @fall_max: Max fall time of both SDA and SCL signals (ns)
 136  * @rise_max: Max rise time of both SDA and SCL signals (ns)
 137  * @hddat_min: Min data hold time (ns)
 138  * @vddat_max: Max data valid time (ns)
 139  * @sudat_min: Min data setup time (ns)
 140  * @l_min: Min low period of the SCL clock (ns)
 141  * @h_min: Min high period of the SCL clock (ns)
 142  */
 143
 144 struct stm32_i2c_spec {
 145         u32 rate;
 146         u32 rate_min;
 147         u32 rate_max;
 148         u32 fall_max;
 149         u32 rise_max;
 150         u32 hddat_min;
 151         u32 vddat_max;
 152         u32 sudat_min;
 153         u32 l_min;
 154         u32 h_min;
 155 };
 156
 157 /**
 158  * struct stm32_i2c_setup - private I2C timing setup parameters
 159  * @speed: I2C speed mode (standard, Fast Plus)
 160  * @speed_freq: I2C speed frequency  (Hz)
 161  * @clock_src: I2C clock source frequency (Hz)
 162  * @rise_time: Rise time (ns)
 163  * @fall_time: Fall time (ns)
 164  * @dnf: Digital filter coefficient (0-16)
 165  * @analog_filter: Analog filter delay (On/Off)
 166  */
 167 struct stm32_i2c_setup {
 168         enum stm32_i2c_speed speed;
 169         u32 speed_freq;
 170         u32 clock_src;
 171         u32 rise_time;
 172         u32 fall_time;
 173         u8 dnf;
 174         bool analog_filter;
 175 };
 176
 177 /**
 178  * struct stm32_i2c_timings - private I2C output parameters
 179  * @prec: Prescaler value
 180  * @scldel: Data setup time
 181  * @sdadel: Data hold time
 182  * @sclh: SCL high period (master mode)
 183  * @sclh: SCL low period (master mode)
 184  */
 185 struct stm32_i2c_timings {
 186         struct list_head node;
 187         u8 presc;
 188         u8 scldel;
 189         u8 sdadel;
 190         u8 sclh;
 191         u8 scll;
 192 };
 193
 194 struct stm32_i2c_priv {
 195         struct stm32_i2c_regs *regs;
 196         struct clk clk;
 197         struct stm32_i2c_setup *setup;
 198         int speed;
 199 };
 200
 201 static struct stm32_i2c_spec i2c_specs[] = {
 202         [STM32_I2C_SPEED_STANDARD] = {
 203                 .rate = STANDARD_RATE,
 204                 .rate_min = 8000,
 205                 .rate_max = 120000,
 206                 .fall_max = 300,
 207                 .rise_max = 1000,
 208                 .hddat_min = 0,
 209                 .vddat_max = 3450,
 210                 .sudat_min = 250,
 211                 .l_min = 4700,
 212                 .h_min = 4000,
 213         },
 214         [STM32_I2C_SPEED_FAST] = {
 215                 .rate = FAST_RATE,
 216                 .rate_min = 320000,
 217                 .rate_max = 480000,
 218                 .fall_max = 300,
 219                 .rise_max = 300,
 220                 .hddat_min = 0,
 221                 .vddat_max = 900,
 222                 .sudat_min = 100,
 223                 .l_min = 1300,
 224                 .h_min = 600,
 225         },
 226         [STM32_I2C_SPEED_FAST_PLUS] = {
 227                 .rate = FAST_PLUS_RATE,
 228                 .rate_min = 800000,
 229                 .rate_max = 1200000,
 230                 .fall_max = 100,
 231                 .rise_max = 120,
 232                 .hddat_min = 0,
 233                 .vddat_max = 450,
 234                 .sudat_min = 50,
 235                 .l_min = 500,
 236                 .h_min = 260,
 237         },
 238 };
 239
 240 static struct stm32_i2c_setup stm32f7_setup = {
 241         .rise_time = STM32_I2C_RISE_TIME_DEFAULT,
 242         .fall_time = STM32_I2C_FALL_TIME_DEFAULT,
 243         .dnf = STM32_I2C_DNF_DEFAULT,
 244         .analog_filter = STM32_I2C_ANALOG_FILTER_ENABLE,
 245 };
 246
 247 DECLARE_GLOBAL_DATA_PTR;
 248
 249 static int stm32_i2c_check_device_busy(struct stm32_i2c_priv *i2c_priv)
 250 {
 251         struct stm32_i2c_regs *regs = i2c_priv->regs;
 252         u32 status = readl(&regs->isr);
 253
 254         if (status & STM32_I2C_ISR_BUSY)
 255                 return -EBUSY;
 256
 257         return 0;
 258 }
 259
 260 static void stm32_i2c_message_start(struct stm32_i2c_priv *i2c_priv,
 261                                       struct i2c_msg *msg, bool stop)
 262 {
 263         struct stm32_i2c_regs *regs = i2c_priv->regs;
 264         u32 cr2 = readl(&regs->cr2);
 265
 266         /* Set transfer direction */
 267         cr2 &= ~STM32_I2C_CR2_RD_WRN;
 268         if (msg->flags & I2C_M_RD)
 269                 cr2 |= STM32_I2C_CR2_RD_WRN;
 270
 271         /* Set slave address */
 272         cr2 &= ~(STM32_I2C_CR2_HEAD10R | STM32_I2C_CR2_ADD10);
 273         if (msg->flags & I2C_M_TEN) {
 274                 cr2 &= ~STM32_I2C_CR2_SADD10_MASK;
 275                 cr2 |= STM32_I2C_CR2_SADD10(msg->addr);
 276                 cr2 |= STM32_I2C_CR2_ADD10;
 277         } else {
 278                 cr2 &= ~STM32_I2C_CR2_SADD7_MASK;
 279                 cr2 |= STM32_I2C_CR2_SADD7(msg->addr);
 280         }
 281
 282         /* Set nb bytes to transfer and reload or autoend bits */
 283         cr2 &= ~(STM32_I2C_CR2_NBYTES_MASK | STM32_I2C_CR2_RELOAD |
 284                  STM32_I2C_CR2_AUTOEND);
 285         if (msg->len > STM32_I2C_MAX_LEN) {
 286                 cr2 |= STM32_I2C_CR2_NBYTES(STM32_I2C_MAX_LEN);
 287                 cr2 |= STM32_I2C_CR2_RELOAD;
 288         } else {
 289                 cr2 |= STM32_I2C_CR2_NBYTES(msg->len);
 290         }
 291
 292         /* Write configurations register */
 293         writel(cr2, &regs->cr2);
 294
 295         /* START/ReSTART generation */
 296         setbits_le32(&regs->cr2, STM32_I2C_CR2_START);
 297 }
 298
 299 /*
 300  * RELOAD mode must be selected if total number of data bytes to be
 301  * sent is greater than MAX_LEN
 302  */
 303
 304 static void stm32_i2c_handle_reload(struct stm32_i2c_priv *i2c_priv,
 305                                       struct i2c_msg *msg, bool stop)
 306 {
 307         struct stm32_i2c_regs *regs = i2c_priv->regs;
 308         u32 cr2 = readl(&regs->cr2);
 309
 310         cr2 &= ~STM32_I2C_CR2_NBYTES_MASK;
 311
 312         if (msg->len > STM32_I2C_MAX_LEN) {
 313                 cr2 |= STM32_I2C_CR2_NBYTES(STM32_I2C_MAX_LEN);
 314         } else {
 315                 cr2 &= ~STM32_I2C_CR2_RELOAD;
 316                 cr2 |= STM32_I2C_CR2_NBYTES(msg->len);
 317         }
 318
 319         writel(cr2, &regs->cr2);
 320 }
 321
 322 static int stm32_i2c_wait_flags(struct stm32_i2c_priv *i2c_priv,
 323                                   u32 flags, u32 *status)
 324 {
 325         struct stm32_i2c_regs *regs = i2c_priv->regs;
 326         u32 time_start = get_timer(0);
 327
 328         *status = readl(&regs->isr);
 329         while (!(*status & flags)) {
 330                 if (get_timer(time_start) > CONFIG_SYS_HZ) {
 331                         debug("%s: i2c timeout\n", __func__);
 332                         return -ETIMEDOUT;
 333                 }
 334
 335                 *status = readl(&regs->isr);
 336         }
 337
 338         return 0;
 339 }
 340
 341 static int stm32_i2c_check_end_of_message(struct stm32_i2c_priv *i2c_priv)
 342 {
 343         struct stm32_i2c_regs *regs = i2c_priv->regs;
 344         u32 mask = STM32_I2C_ISR_ERRORS | STM32_I2C_ISR_NACKF |
 345                    STM32_I2C_ISR_STOPF;
 346         u32 status;
 347         int ret;
 348
 349         ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
 350         if (ret)
 351                 return ret;
 352
 353         if (status & STM32_I2C_ISR_BERR) {
 354                 debug("%s: Bus error\n", __func__);
 355
 356                 /* Clear BERR flag */
 357                 setbits_le32(&regs->icr, STM32_I2C_ICR_BERRCF);
 358
 359                 return -EIO;
 360         }
 361
 362         if (status & STM32_I2C_ISR_ARLO) {
 363                 debug("%s: Arbitration lost\n", __func__);
 364
 365                 /* Clear ARLO flag */
 366                 setbits_le32(&regs->icr, STM32_I2C_ICR_ARLOCF);
 367
 368                 return -EAGAIN;
 369         }
 370
 371         if (status & STM32_I2C_ISR_NACKF) {
 372                 debug("%s: Receive NACK\n", __func__);
 373
 374                 /* Clear NACK flag */
 375                 setbits_le32(&regs->icr, STM32_I2C_ICR_NACKCF);
 376
 377                 /* Wait until STOPF flag is set */
 378                 mask = STM32_I2C_ISR_STOPF;
 379                 ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
 380                 if (ret)
 381                         return ret;
 382
 383                 ret = -EIO;
 384         }
 385
 386         if (status & STM32_I2C_ISR_STOPF) {
 387                 /* Clear STOP flag */
 388                 setbits_le32(&regs->icr, STM32_I2C_ICR_STOPCF);
 389
 390                 /* Clear control register 2 */
 391                 setbits_le32(&regs->cr2, STM32_I2C_CR2_RESET_MASK);
 392         }
 393
 394         return ret;
 395 }
 396
 397 static int stm32_i2c_message_xfer(struct stm32_i2c_priv *i2c_priv,
 398                                     struct i2c_msg *msg, bool stop)
 399 {
 400         struct stm32_i2c_regs *regs = i2c_priv->regs;
 401         u32 status;
 402         u32 mask = msg->flags & I2C_M_RD ? STM32_I2C_ISR_RXNE :
 403                    STM32_I2C_ISR_TXIS | STM32_I2C_ISR_NACKF;
 404         int bytes_to_rw = msg->len > STM32_I2C_MAX_LEN ?
 405                           STM32_I2C_MAX_LEN : msg->len;
 406         int ret = 0;
 407
 408         /* Add errors */
 409         mask |= STM32_I2C_ISR_ERRORS;
 410
 411         stm32_i2c_message_start(i2c_priv, msg, stop);
 412
 413         while (msg->len) {
 414                 /*
 415                  * Wait until TXIS/NACKF/BERR/ARLO flags or
 416                  * RXNE/BERR/ARLO flags are set
 417                  */
 418                 ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
 419                 if (ret)
 420                         break;
 421
 422                 if (status & (STM32_I2C_ISR_NACKF | STM32_I2C_ISR_ERRORS))
 423                         break;
 424
 425                 if (status & STM32_I2C_ISR_RXNE) {
 426                         *msg->buf++ = readb(&regs->rxdr);
 427                         msg->len--;
 428                         bytes_to_rw--;
 429                 }
 430
 431                 if (status & STM32_I2C_ISR_TXIS) {
 432                         writeb(*msg->buf++, &regs->txdr);
 433                         msg->len--;
 434                         bytes_to_rw--;
 435                 }
 436
 437                 if (!bytes_to_rw && msg->len) {
 438                         /* Wait until TCR flag is set */
 439                         mask = STM32_I2C_ISR_TCR;
 440                         ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
 441                         if (ret)
 442                                 break;
 443
 444                         bytes_to_rw = msg->len > STM32_I2C_MAX_LEN ?
 445                                       STM32_I2C_MAX_LEN : msg->len;
 446                         mask = msg->flags & I2C_M_RD ? STM32_I2C_ISR_RXNE :
 447                                STM32_I2C_ISR_TXIS | STM32_I2C_ISR_NACKF;
 448
 449                         stm32_i2c_handle_reload(i2c_priv, msg, stop);
 450                 } else if (!bytes_to_rw) {
 451                         /* Wait until TC flag is set */
 452                         mask = STM32_I2C_ISR_TC;
 453                         ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
 454                         if (ret)
 455                                 break;
 456
 457                         if (!stop)
 458                                 /* Message sent, new message has to be sent */
 459                                 return 0;
 460                 }
 461         }
 462
 463         /* End of transfer, send stop condition */
 464         mask = STM32_I2C_CR2_STOP;
 465         setbits_le32(&regs->cr2, mask);
 466
 467         return stm32_i2c_check_end_of_message(i2c_priv);
 468 }
 469
 470 static int stm32_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
 471                             int nmsgs)
 472 {
 473         struct stm32_i2c_priv *i2c_priv = dev_get_priv(bus);
 474         int ret;
 475
 476         ret = stm32_i2c_check_device_busy(i2c_priv);
 477         if (ret)
 478                 return ret;
 479
 480         for (; nmsgs > 0; nmsgs--, msg++) {
 481                 ret = stm32_i2c_message_xfer(i2c_priv, msg, nmsgs == 1);
 482                 if (ret)
 483                         return ret;
 484         }
 485
 486         return 0;
 487 }
 488
 489 static int stm32_i2c_compute_solutions(struct stm32_i2c_setup *setup,
 490                                        struct list_head *solutions)
 491 {
 492         struct stm32_i2c_timings *v;
 493         u32 p_prev = STM32_PRESC_MAX;
 494         u32 i2cclk = DIV_ROUND_CLOSEST(STM32_NSEC_PER_SEC,
 495                                        setup->clock_src);
 496         u32 af_delay_min, af_delay_max;
 497         u16 p, l, a;
 498         int sdadel_min, sdadel_max, scldel_min;
 499         int ret = 0;
 500
 501         af_delay_min = setup->analog_filter ?
 502                        STM32_I2C_ANALOG_FILTER_DELAY_MIN : 0;
 503         af_delay_max = setup->analog_filter ?
 504                        STM32_I2C_ANALOG_FILTER_DELAY_MAX : 0;
 505
 506         sdadel_min = setup->fall_time - i2c_specs[setup->speed].hddat_min -
 507                      af_delay_min - (setup->dnf + 3) * i2cclk;
 508
 509         sdadel_max = i2c_specs[setup->speed].vddat_max - setup->rise_time -
 510                      af_delay_max - (setup->dnf + 4) * i2cclk;
 511
 512         scldel_min = setup->rise_time + i2c_specs[setup->speed].sudat_min;
 513
 514         if (sdadel_min < 0)
 515                 sdadel_min = 0;
 516         if (sdadel_max < 0)
 517                 sdadel_max = 0;
 518
 519         debug("%s: SDADEL(min/max): %i/%i, SCLDEL(Min): %i\n", __func__,
 520               sdadel_min, sdadel_max, scldel_min);
 521
 522         /* Compute possible values for PRESC, SCLDEL and SDADEL */
 523         for (p = 0; p < STM32_PRESC_MAX; p++) {
 524                 for (l = 0; l < STM32_SCLDEL_MAX; l++) {
 525                         u32 scldel = (l + 1) * (p + 1) * i2cclk;
 526
 527                         if (scldel < scldel_min)
 528                                 continue;
 529
 530                         for (a = 0; a < STM32_SDADEL_MAX; a++) {
 531                                 u32 sdadel = (a * (p + 1) + 1) * i2cclk;
 532
 533                                 if (((sdadel >= sdadel_min) &&
 534                                      (sdadel <= sdadel_max)) &&
 535                                     (p != p_prev)) {
 536                                         v = kmalloc(sizeof(*v), GFP_KERNEL);
 537                                         if (!v)
 538                                                 return -ENOMEM;
 539
 540                                         v->presc = p;
 541                                         v->scldel = l;
 542                                         v->sdadel = a;
 543                                         p_prev = p;
 544
 545                                         list_add_tail(&v->node, solutions);
 546                                 }
 547                         }
 548                 }
 549         }
 550
 551         if (list_empty(solutions)) {
 552                 pr_err("%s: no Prescaler solution\n", __func__);
 553                 ret = -EPERM;
 554         }
 555
 556         return ret;
 557 }
 558
 559 static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
 560                                      struct list_head *solutions,
 561                                      struct stm32_i2c_timings *s)
 562 {
 563         struct stm32_i2c_timings *v;
 564         u32 i2cbus = DIV_ROUND_CLOSEST(STM32_NSEC_PER_SEC,
 565                                        setup->speed_freq);
 566         u32 clk_error_prev = i2cbus;
 567         u32 i2cclk = DIV_ROUND_CLOSEST(STM32_NSEC_PER_SEC,
 568                                        setup->clock_src);
 569         u32 clk_min, clk_max;
 570         u32 af_delay_min;
 571         u32 dnf_delay;
 572         u32 tsync;
 573         u16 l, h;
 574         int ret = 0;
 575
 576         af_delay_min = setup->analog_filter ?
 577                        STM32_I2C_ANALOG_FILTER_DELAY_MIN : 0;
 578         dnf_delay = setup->dnf * i2cclk;
 579
 580         tsync = af_delay_min + dnf_delay + (2 * i2cclk);
 581         clk_max = STM32_NSEC_PER_SEC / i2c_specs[setup->speed].rate_min;
 582         clk_min = STM32_NSEC_PER_SEC / i2c_specs[setup->speed].rate_max;
 583
 584         /*
 585          * Among Prescaler possibilities discovered above figures out SCL Low
 586          * and High Period. Provided:
 587          * - SCL Low Period has to be higher than Low Period of the SCL Clock
 588          *   defined by I2C Specification. I2C Clock has to be lower than
 589          *   (SCL Low Period - Analog/Digital filters) / 4.
 590          * - SCL High Period has to be lower than High Period of the SCL Clock
 591          *   defined by I2C Specification
 592          * - I2C Clock has to be lower than SCL High Period
 593          */
 594         list_for_each_entry(v, solutions, node) {
 595                 u32 prescaler = (v->presc + 1) * i2cclk;
 596
 597                 for (l = 0; l < STM32_SCLL_MAX; l++) {
 598                         u32 tscl_l = (l + 1) * prescaler + tsync;
 599                         if ((tscl_l < i2c_specs[setup->speed].l_min) ||
 600                             (i2cclk >=
 601                              ((tscl_l - af_delay_min - dnf_delay) / 4))) {
 602                                 continue;
 603                         }
 604
 605                         for (h = 0; h < STM32_SCLH_MAX; h++) {
 606                                 u32 tscl_h = (h + 1) * prescaler + tsync;
 607                                 u32 tscl = tscl_l + tscl_h +
 608                                            setup->rise_time + setup->fall_time;
 609
 610                                 if ((tscl >= clk_min) && (tscl <= clk_max) &&
 611                                     (tscl_h >= i2c_specs[setup->speed].h_min) &&
 612                                     (i2cclk < tscl_h)) {
 613                                         int clk_error = tscl - i2cbus;
 614
 615                                         if (clk_error < 0)
 616                                                 clk_error = -clk_error;
 617
 618                                         if (clk_error < clk_error_prev) {
 619                                                 clk_error_prev = clk_error;
 620                                                 v->scll = l;
 621                                                 v->sclh = h;
 622                                                 s = v;
 623                                         }
 624                                 }
 625                         }
 626                 }
 627         }
 628
 629         if (!s) {
 630                 pr_err("%s: no solution at all\n", __func__);
 631                 ret = -EPERM;
 632         }
 633
 634         return ret;
 635 }
 636
 637 static int stm32_i2c_compute_timing(struct stm32_i2c_priv *i2c_priv,
 638                                       struct stm32_i2c_setup *setup,
 639                                       struct stm32_i2c_timings *output)
 640 {
 641         struct stm32_i2c_timings *v, *_v, *s;
 642         struct list_head solutions;
 643         int ret;
 644
 645         if (setup->speed >= STM32_I2C_SPEED_END) {
 646                 pr_err("%s: speed out of bound {%d/%d}\n", __func__,
 647                       setup->speed, STM32_I2C_SPEED_END - 1);
 648                 return -EINVAL;
 649         }
 650
 651         if ((setup->rise_time > i2c_specs[setup->speed].rise_max) ||
 652             (setup->fall_time > i2c_specs[setup->speed].fall_max)) {
 653                 pr_err("%s :timings out of bound Rise{%d>%d}/Fall{%d>%d}\n",
 654                       __func__,
 655                       setup->rise_time, i2c_specs[setup->speed].rise_max,
 656                       setup->fall_time, i2c_specs[setup->speed].fall_max);
 657                 return -EINVAL;
 658         }
 659
 660         if (setup->dnf > STM32_I2C_DNF_MAX) {
 661                 pr_err("%s: DNF out of bound %d/%d\n", __func__,
 662                       setup->dnf, STM32_I2C_DNF_MAX);
 663                 return -EINVAL;
 664         }
 665
 666         if (setup->speed_freq > i2c_specs[setup->speed].rate) {
 667                 pr_err("%s: Freq {%d/%d}\n", __func__,
 668                       setup->speed_freq, i2c_specs[setup->speed].rate);
 669                 return -EINVAL;
 670         }
 671
 672         s = NULL;
 673         INIT_LIST_HEAD(&solutions);
 674         ret = stm32_i2c_compute_solutions(setup, &solutions);
 675         if (ret)
 676                 goto exit;
 677
 678         ret = stm32_i2c_choose_solution(setup, &solutions, s);
 679         if (ret)
 680                 goto exit;
 681
 682         output->presc = s->presc;
 683         output->scldel = s->scldel;
 684         output->sdadel = s->sdadel;
 685         output->scll = s->scll;
 686         output->sclh = s->sclh;
 687
 688         debug("%s: Presc: %i, scldel: %i, sdadel: %i, scll: %i, sclh: %i\n",
 689               __func__, output->presc,
 690               output->scldel, output->sdadel,
 691               output->scll, output->sclh);
 692
 693 exit:
 694         /* Release list and memory */
 695         list_for_each_entry_safe(v, _v, &solutions, node) {
 696                 list_del(&v->node);
 697                 kfree(v);
 698         }
 699
 700         return ret;
 701 }
 702
 703 static int stm32_i2c_setup_timing(struct stm32_i2c_priv *i2c_priv,
 704                                     struct stm32_i2c_timings *timing)
 705 {
 706         struct stm32_i2c_setup *setup = i2c_priv->setup;
 707         int ret = 0;
 708
 709         setup->speed = i2c_priv->speed;
 710         setup->speed_freq = i2c_specs[setup->speed].rate;
 711         setup->clock_src = clk_get_rate(&i2c_priv->clk);
 712
 713         if (!setup->clock_src) {
 714                 pr_err("%s: clock rate is 0\n", __func__);
 715                 return -EINVAL;
 716         }
 717
 718         do {
 719                 ret = stm32_i2c_compute_timing(i2c_priv, setup, timing);
 720                 if (ret) {
 721                         debug("%s: failed to compute I2C timings.\n",
 722                               __func__);
 723                         if (i2c_priv->speed > STM32_I2C_SPEED_STANDARD) {
 724                                 i2c_priv->speed--;
 725                                 setup->speed = i2c_priv->speed;
 726                                 setup->speed_freq =
 727                                         i2c_specs[setup->speed].rate;
 728                                 debug("%s: downgrade I2C Speed Freq to (%i)\n",
 729                                       __func__, i2c_specs[setup->speed].rate);
 730                         } else {
 731                                 break;
 732                         }
 733                 }
 734         } while (ret);
 735
 736         if (ret) {
 737                 pr_err("%s: impossible to compute I2C timings.\n", __func__);
 738                 return ret;
 739         }
 740
 741         debug("%s: I2C Speed(%i), Freq(%i), Clk Source(%i)\n", __func__,
 742               setup->speed, setup->speed_freq, setup->clock_src);
 743         debug("%s: I2C Rise(%i) and Fall(%i) Time\n", __func__,
 744               setup->rise_time, setup->fall_time);
 745         debug("%s: I2C Analog Filter(%s), DNF(%i)\n", __func__,
 746               setup->analog_filter ? "On" : "Off", setup->dnf);
 747
 748         return 0;
 749 }
 750
 751 static int stm32_i2c_hw_config(struct stm32_i2c_priv *i2c_priv)
 752 {
 753         struct stm32_i2c_regs *regs = i2c_priv->regs;
 754         struct stm32_i2c_timings t;
 755         int ret;
 756         u32 timing = 0;
 757
 758         ret = stm32_i2c_setup_timing(i2c_priv, &t);
 759         if (ret)
 760                 return ret;
 761
 762         /* Disable I2C */
 763         clrbits_le32(&regs->cr1, STM32_I2C_CR1_PE);
 764
 765         /* Timing settings */
 766         timing |= STM32_I2C_TIMINGR_PRESC(t.presc);
 767         timing |= STM32_I2C_TIMINGR_SCLDEL(t.scldel);
 768         timing |= STM32_I2C_TIMINGR_SDADEL(t.sdadel);
 769         timing |= STM32_I2C_TIMINGR_SCLH(t.sclh);
 770         timing |= STM32_I2C_TIMINGR_SCLL(t.scll);
 771         writel(timing, &regs->timingr);
 772
 773         /* Enable I2C */
 774         if (i2c_priv->setup->analog_filter)
 775                 clrbits_le32(&regs->cr1, STM32_I2C_CR1_ANFOFF);
 776         else
 777                 setbits_le32(&regs->cr1, STM32_I2C_CR1_ANFOFF);
 778         setbits_le32(&regs->cr1, STM32_I2C_CR1_PE);
 779
 780         return 0;
 781 }
 782
 783 static int stm32_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
 784 {
 785         struct stm32_i2c_priv *i2c_priv = dev_get_priv(bus);
 786
 787         switch (speed) {
 788         case STANDARD_RATE:
 789                 i2c_priv->speed = STM32_I2C_SPEED_STANDARD;
 790                 break;
 791         case FAST_RATE:
 792                 i2c_priv->speed = STM32_I2C_SPEED_FAST;
 793                 break;
 794         case FAST_PLUS_RATE:
 795                 i2c_priv->speed = STM32_I2C_SPEED_FAST_PLUS;
 796                 break;
 797         default:
 798                 debug("%s: Speed %d not supported\n", __func__, speed);
 799                 return -EINVAL;
 800         }
 801
 802         return stm32_i2c_hw_config(i2c_priv);
 803 }
 804
 805 static int stm32_i2c_probe(struct udevice *dev)
 806 {
 807         struct stm32_i2c_priv *i2c_priv = dev_get_priv(dev);
 808         struct reset_ctl reset_ctl;
 809         fdt_addr_t addr;
 810         int ret;
 811
 812         addr = dev_read_addr(dev);
 813         if (addr == FDT_ADDR_T_NONE)
 814                 return -EINVAL;
 815
 816         i2c_priv->regs = (struct stm32_i2c_regs *)addr;
 817
 818         ret = clk_get_by_index(dev, 0, &i2c_priv->clk);
 819         if (ret)
 820                 return ret;
 821
 822         ret = clk_enable(&i2c_priv->clk);
 823         if (ret)
 824                 goto clk_free;
 825
 826         ret = reset_get_by_index(dev, 0, &reset_ctl);
 827         if (ret)
 828                 goto clk_disable;
 829
 830         reset_assert(&reset_ctl);
 831         udelay(2);
 832         reset_deassert(&reset_ctl);
 833
 834         return 0;
 835
 836 clk_disable:
 837         clk_disable(&i2c_priv->clk);
 838 clk_free:
 839         clk_free(&i2c_priv->clk);
 840
 841         return ret;
 842 }
 843
 844 static int stm32_ofdata_to_platdata(struct udevice *dev)
 845 {
 846         struct stm32_i2c_priv *i2c_priv = dev_get_priv(dev);
 847         u32 rise_time, fall_time;
 848
 849         i2c_priv->setup = (struct stm32_i2c_setup *)dev_get_driver_data(dev);
 850         if (!i2c_priv->setup)
 851                 return -EINVAL;
 852
 853         rise_time = dev_read_u32_default(dev, "i2c-scl-rising-time-ns", 0);
 854         if (rise_time)
 855                 i2c_priv->setup->rise_time = rise_time;
 856
 857         fall_time = dev_read_u32_default(dev, "i2c-scl-falling-time-ns", 0);
 858         if (fall_time)
 859                 i2c_priv->setup->fall_time = fall_time;
 860
 861         return 0;
 862 }
 863
 864 static const struct dm_i2c_ops stm32_i2c_ops = {
 865         .xfer = stm32_i2c_xfer,
 866         .set_bus_speed = stm32_i2c_set_bus_speed,
 867 };
 868
 869 static const struct udevice_id stm32_i2c_of_match[] = {
 870         { .compatible = "st,stm32f7-i2c", .data = (ulong)&stm32f7_setup },
 871         {}
 872 };
 873
 874 U_BOOT_DRIVER(stm32f7_i2c) = {
 875         .name = "stm32f7-i2c",
 876         .id = UCLASS_I2C,
 877         .of_match = stm32_i2c_of_match,
 878         .ofdata_to_platdata = stm32_ofdata_to_platdata,
 879         .probe = stm32_i2c_probe,
 880         .priv_auto_alloc_size = sizeof(struct stm32_i2c_priv),
 881         .ops = &stm32_i2c_ops,
 882 };