1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * I2C adapter for the IMG Serial Control Bus (SCB) IP block. 4 * 5 * Copyright (C) 2009, 2010, 2012, 2014 Imagination Technologies Ltd. 6 * 7 * There are three ways that this I2C controller can be driven: 8 * 9 * - Raw control of the SDA and SCK signals. 10 * 11 * This corresponds to MODE_RAW, which takes control of the signals 12 * directly for a certain number of clock cycles (the INT_TIMING 13 * interrupt can be used for timing). 14 * 15 * - Atomic commands. A low level I2C symbol (such as generate 16 * start/stop/ack/nack bit, generate byte, receive byte, and receive 17 * ACK) is given to the hardware, with detection of completion by bits 18 * in the LINESTAT register. 19 * 20 * This mode of operation is used by MODE_ATOMIC, which uses an I2C 21 * state machine in the interrupt handler to compose/react to I2C 22 * transactions using atomic mode commands, and also by MODE_SEQUENCE, 23 * which emits a simple fixed sequence of atomic mode commands. 24 * 25 * Due to software control, the use of atomic commands usually results 26 * in suboptimal use of the bus, with gaps between the I2C symbols while 27 * the driver decides what to do next. 28 * 29 * - Automatic mode. A bus address, and whether to read/write is 30 * specified, and the hardware takes care of the I2C state machine, 31 * using a FIFO to send/receive bytes of data to an I2C slave. The 32 * driver just has to keep the FIFO drained or filled in response to the 33 * appropriate FIFO interrupts. 34 * 35 * This corresponds to MODE_AUTOMATIC, which manages the FIFOs and deals 36 * with control of repeated start bits between I2C messages. 37 * 38 * Use of automatic mode and the FIFO can make much more efficient use 39 * of the bus compared to individual atomic commands, with potentially 40 * no wasted time between I2C symbols or I2C messages. 41 * 42 * In most cases MODE_AUTOMATIC is used, however if any of the messages in 43 * a transaction are zero byte writes (e.g. used by i2cdetect for probing 44 * the bus), MODE_ATOMIC must be used since automatic mode is normally 45 * started by the writing of data into the FIFO. 46 * 47 * The other modes are used in specific circumstances where MODE_ATOMIC and 48 * MODE_AUTOMATIC aren't appropriate. MODE_RAW is used to implement a bus 49 * recovery routine. MODE_SEQUENCE is used to reset the bus and make sure 50 * it is in a sane state. 51 * 52 * Notice that the driver implements a timer-based timeout mechanism. 53 * The reason for this mechanism is to reduce the number of interrupts 54 * received in automatic mode. 55 * 56 * The driver would get a slave event and transaction done interrupts for 57 * each atomic mode command that gets completed. However, these events are 58 * not needed in automatic mode, becase those atomic mode commands are 59 * managed automatically by the hardware. 60 * 61 * In practice, normal I2C transactions will be complete well before you 62 * get the timer interrupt, as the timer is re-scheduled during FIFO 63 * maintenance and disabled after the transaction is complete. 64 * 65 * In this way normal automatic mode operation isn't impacted by 66 * unnecessary interrupts, but the exceptional abort condition can still be 67 * detected (with a slight delay). 68 */ 69 70 #include <linux/bitops.h> 71 #include <linux/clk.h> 72 #include <linux/completion.h> 73 #include <linux/err.h> 74 #include <linux/i2c.h> 75 #include <linux/init.h> 76 #include <linux/interrupt.h> 77 #include <linux/io.h> 78 #include <linux/kernel.h> 79 #include <linux/module.h> 80 #include <linux/of_platform.h> 81 #include <linux/platform_device.h> 82 #include <linux/pm_runtime.h> 83 #include <linux/slab.h> 84 #include <linux/timer.h> 85 86 /* Register offsets */ 87 88 #define SCB_STATUS_REG 0x00 89 #define SCB_OVERRIDE_REG 0x04 90 #define SCB_READ_ADDR_REG 0x08 91 #define SCB_READ_COUNT_REG 0x0c 92 #define SCB_WRITE_ADDR_REG 0x10 93 #define SCB_READ_DATA_REG 0x14 94 #define SCB_WRITE_DATA_REG 0x18 95 #define SCB_FIFO_STATUS_REG 0x1c 96 #define SCB_CONTROL_SOFT_RESET 0x1f 97 #define SCB_CLK_SET_REG 0x3c 98 #define SCB_INT_STATUS_REG 0x40 99 #define SCB_INT_CLEAR_REG 0x44 100 #define SCB_INT_MASK_REG 0x48 101 #define SCB_CONTROL_REG 0x4c 102 #define SCB_TIME_TPL_REG 0x50 103 #define SCB_TIME_TPH_REG 0x54 104 #define SCB_TIME_TP2S_REG 0x58 105 #define SCB_TIME_TBI_REG 0x60 106 #define SCB_TIME_TSL_REG 0x64 107 #define SCB_TIME_TDL_REG 0x68 108 #define SCB_TIME_TSDL_REG 0x6c 109 #define SCB_TIME_TSDH_REG 0x70 110 #define SCB_READ_XADDR_REG 0x74 111 #define SCB_WRITE_XADDR_REG 0x78 112 #define SCB_WRITE_COUNT_REG 0x7c 113 #define SCB_CORE_REV_REG 0x80 114 #define SCB_TIME_TCKH_REG 0x84 115 #define SCB_TIME_TCKL_REG 0x88 116 #define SCB_FIFO_FLUSH_REG 0x8c 117 #define SCB_READ_FIFO_REG 0x94 118 #define SCB_CLEAR_REG 0x98 119 120 /* SCB_CONTROL_REG bits */ 121 122 #define SCB_CONTROL_CLK_ENABLE 0x1e0 123 #define SCB_CONTROL_TRANSACTION_HALT 0x200 124 125 #define FIFO_READ_FULL BIT(0) 126 #define FIFO_READ_EMPTY BIT(1) 127 #define FIFO_WRITE_FULL BIT(2) 128 #define FIFO_WRITE_EMPTY BIT(3) 129 130 /* SCB_CLK_SET_REG bits */ 131 #define SCB_FILT_DISABLE BIT(31) 132 #define SCB_FILT_BYPASS BIT(30) 133 #define SCB_FILT_INC_MASK 0x7f 134 #define SCB_FILT_INC_SHIFT 16 135 #define SCB_INC_MASK 0x7f 136 #define SCB_INC_SHIFT 8 137 138 /* SCB_INT_*_REG bits */ 139 140 #define INT_BUS_INACTIVE BIT(0) 141 #define INT_UNEXPECTED_START BIT(1) 142 #define INT_SCLK_LOW_TIMEOUT BIT(2) 143 #define INT_SDAT_LOW_TIMEOUT BIT(3) 144 #define INT_WRITE_ACK_ERR BIT(4) 145 #define INT_ADDR_ACK_ERR BIT(5) 146 #define INT_FIFO_FULL BIT(9) 147 #define INT_FIFO_FILLING BIT(10) 148 #define INT_FIFO_EMPTY BIT(11) 149 #define INT_FIFO_EMPTYING BIT(12) 150 #define INT_TRANSACTION_DONE BIT(15) 151 #define INT_SLAVE_EVENT BIT(16) 152 #define INT_MASTER_HALTED BIT(17) 153 #define INT_TIMING BIT(18) 154 #define INT_STOP_DETECTED BIT(19) 155 156 #define INT_FIFO_FULL_FILLING (INT_FIFO_FULL | INT_FIFO_FILLING) 157 158 /* Level interrupts need clearing after handling instead of before */ 159 #define INT_LEVEL 0x01e00 160 161 /* Don't allow any interrupts while the clock may be off */ 162 #define INT_ENABLE_MASK_INACTIVE 0x00000 163 164 /* Interrupt masks for the different driver modes */ 165 166 #define INT_ENABLE_MASK_RAW INT_TIMING 167 168 #define INT_ENABLE_MASK_ATOMIC (INT_TRANSACTION_DONE | \ 169 INT_SLAVE_EVENT | \ 170 INT_ADDR_ACK_ERR | \ 171 INT_WRITE_ACK_ERR) 172 173 #define INT_ENABLE_MASK_AUTOMATIC (INT_SCLK_LOW_TIMEOUT | \ 174 INT_ADDR_ACK_ERR | \ 175 INT_WRITE_ACK_ERR | \ 176 INT_FIFO_FULL | \ 177 INT_FIFO_FILLING | \ 178 INT_FIFO_EMPTY | \ 179 INT_MASTER_HALTED | \ 180 INT_STOP_DETECTED) 181 182 #define INT_ENABLE_MASK_WAITSTOP (INT_SLAVE_EVENT | \ 183 INT_ADDR_ACK_ERR | \ 184 INT_WRITE_ACK_ERR) 185 186 /* SCB_STATUS_REG fields */ 187 188 #define LINESTAT_SCLK_LINE_STATUS BIT(0) 189 #define LINESTAT_SCLK_EN BIT(1) 190 #define LINESTAT_SDAT_LINE_STATUS BIT(2) 191 #define LINESTAT_SDAT_EN BIT(3) 192 #define LINESTAT_DET_START_STATUS BIT(4) 193 #define LINESTAT_DET_STOP_STATUS BIT(5) 194 #define LINESTAT_DET_ACK_STATUS BIT(6) 195 #define LINESTAT_DET_NACK_STATUS BIT(7) 196 #define LINESTAT_BUS_IDLE BIT(8) 197 #define LINESTAT_T_DONE_STATUS BIT(9) 198 #define LINESTAT_SCLK_OUT_STATUS BIT(10) 199 #define LINESTAT_SDAT_OUT_STATUS BIT(11) 200 #define LINESTAT_GEN_LINE_MASK_STATUS BIT(12) 201 #define LINESTAT_START_BIT_DET BIT(13) 202 #define LINESTAT_STOP_BIT_DET BIT(14) 203 #define LINESTAT_ACK_DET BIT(15) 204 #define LINESTAT_NACK_DET BIT(16) 205 #define LINESTAT_INPUT_HELD_V BIT(17) 206 #define LINESTAT_ABORT_DET BIT(18) 207 #define LINESTAT_ACK_OR_NACK_DET (LINESTAT_ACK_DET | LINESTAT_NACK_DET) 208 #define LINESTAT_INPUT_DATA 0xff000000 209 #define LINESTAT_INPUT_DATA_SHIFT 24 210 211 #define LINESTAT_CLEAR_SHIFT 13 212 #define LINESTAT_LATCHED (0x3f << LINESTAT_CLEAR_SHIFT) 213 214 /* SCB_OVERRIDE_REG fields */ 215 216 #define OVERRIDE_SCLK_OVR BIT(0) 217 #define OVERRIDE_SCLKEN_OVR BIT(1) 218 #define OVERRIDE_SDAT_OVR BIT(2) 219 #define OVERRIDE_SDATEN_OVR BIT(3) 220 #define OVERRIDE_MASTER BIT(9) 221 #define OVERRIDE_LINE_OVR_EN BIT(10) 222 #define OVERRIDE_DIRECT BIT(11) 223 #define OVERRIDE_CMD_SHIFT 4 224 #define OVERRIDE_CMD_MASK 0x1f 225 #define OVERRIDE_DATA_SHIFT 24 226 227 #define OVERRIDE_SCLK_DOWN (OVERRIDE_LINE_OVR_EN | \ 228 OVERRIDE_SCLKEN_OVR) 229 #define OVERRIDE_SCLK_UP (OVERRIDE_LINE_OVR_EN | \ 230 OVERRIDE_SCLKEN_OVR | \ 231 OVERRIDE_SCLK_OVR) 232 #define OVERRIDE_SDAT_DOWN (OVERRIDE_LINE_OVR_EN | \ 233 OVERRIDE_SDATEN_OVR) 234 #define OVERRIDE_SDAT_UP (OVERRIDE_LINE_OVR_EN | \ 235 OVERRIDE_SDATEN_OVR | \ 236 OVERRIDE_SDAT_OVR) 237 238 /* OVERRIDE_CMD values */ 239 240 #define CMD_PAUSE 0x00 241 #define CMD_GEN_DATA 0x01 242 #define CMD_GEN_START 0x02 243 #define CMD_GEN_STOP 0x03 244 #define CMD_GEN_ACK 0x04 245 #define CMD_GEN_NACK 0x05 246 #define CMD_RET_DATA 0x08 247 #define CMD_RET_ACK 0x09 248 249 /* Fixed timing values */ 250 251 #define TIMEOUT_TBI 0x0 252 #define TIMEOUT_TSL 0xffff 253 #define TIMEOUT_TDL 0x0 254 255 /* Transaction timeout */ 256 257 #define IMG_I2C_TIMEOUT (msecs_to_jiffies(1000)) 258 259 /* 260 * Worst incs are 1 (inaccurate) and 16*256 (irregular). 261 * So a sensible inc is the logarithmic mean: 64 (2^6), which is 262 * in the middle of the valid range (0-127). 263 */ 264 #define SCB_OPT_INC 64 265 266 /* Setup the clock enable filtering for 25 ns */ 267 #define SCB_FILT_GLITCH 25 268 269 /* 270 * Bits to return from interrupt handler functions for different modes. 271 * This delays completion until we've finished with the registers, so that the 272 * function waiting for completion can safely disable the clock to save power. 273 */ 274 #define ISR_COMPLETE_M BIT(31) 275 #define ISR_FATAL_M BIT(30) 276 #define ISR_WAITSTOP BIT(29) 277 #define ISR_STATUS_M 0x0000ffff /* contains +ve errno */ 278 #define ISR_COMPLETE(err) (ISR_COMPLETE_M | (ISR_STATUS_M & (err))) 279 #define ISR_FATAL(err) (ISR_COMPLETE(err) | ISR_FATAL_M) 280 281 #define IMG_I2C_PM_TIMEOUT 1000 /* ms */ 282 283 enum img_i2c_mode { 284 MODE_INACTIVE, 285 MODE_RAW, 286 MODE_ATOMIC, 287 MODE_AUTOMATIC, 288 MODE_SEQUENCE, 289 MODE_FATAL, 290 MODE_WAITSTOP, 291 MODE_SUSPEND, 292 }; 293 294 /* Timing parameters for i2c modes (in ns) */ 295 struct img_i2c_timings { 296 const char *name; 297 unsigned int max_bitrate; 298 unsigned int tckh, tckl, tsdh, tsdl; 299 unsigned int tp2s, tpl, tph; 300 }; 301 302 /* The timings array must be ordered from slower to faster */ 303 static struct img_i2c_timings timings[] = { 304 /* Standard mode */ 305 { 306 .name = "standard", 307 .max_bitrate = I2C_MAX_STANDARD_MODE_FREQ, 308 .tckh = 4000, 309 .tckl = 4700, 310 .tsdh = 4700, 311 .tsdl = 8700, 312 .tp2s = 4700, 313 .tpl = 4700, 314 .tph = 4000, 315 }, 316 /* Fast mode */ 317 { 318 .name = "fast", 319 .max_bitrate = I2C_MAX_FAST_MODE_FREQ, 320 .tckh = 600, 321 .tckl = 1300, 322 .tsdh = 600, 323 .tsdl = 1200, 324 .tp2s = 1300, 325 .tpl = 600, 326 .tph = 600, 327 }, 328 }; 329 330 /* Reset dance */ 331 static u8 img_i2c_reset_seq[] = { CMD_GEN_START, 332 CMD_GEN_DATA, 0xff, 333 CMD_RET_ACK, 334 CMD_GEN_START, 335 CMD_GEN_STOP, 336 0 }; 337 /* Just issue a stop (after an abort condition) */ 338 static u8 img_i2c_stop_seq[] = { CMD_GEN_STOP, 339 0 }; 340 341 /* We're interested in different interrupts depending on the mode */ 342 static unsigned int img_i2c_int_enable_by_mode[] = { 343 [MODE_INACTIVE] = INT_ENABLE_MASK_INACTIVE, 344 [MODE_RAW] = INT_ENABLE_MASK_RAW, 345 [MODE_ATOMIC] = INT_ENABLE_MASK_ATOMIC, 346 [MODE_AUTOMATIC] = INT_ENABLE_MASK_AUTOMATIC, 347 [MODE_SEQUENCE] = INT_ENABLE_MASK_ATOMIC, 348 [MODE_FATAL] = 0, 349 [MODE_WAITSTOP] = INT_ENABLE_MASK_WAITSTOP, 350 [MODE_SUSPEND] = 0, 351 }; 352 353 /* Atomic command names */ 354 static const char * const img_i2c_atomic_cmd_names[] = { 355 [CMD_PAUSE] = "PAUSE", 356 [CMD_GEN_DATA] = "GEN_DATA", 357 [CMD_GEN_START] = "GEN_START", 358 [CMD_GEN_STOP] = "GEN_STOP", 359 [CMD_GEN_ACK] = "GEN_ACK", 360 [CMD_GEN_NACK] = "GEN_NACK", 361 [CMD_RET_DATA] = "RET_DATA", 362 [CMD_RET_ACK] = "RET_ACK", 363 }; 364 365 struct img_i2c { 366 struct i2c_adapter adap; 367 368 void __iomem *base; 369 370 /* 371 * The scb core clock is used to get the input frequency, and to disable 372 * it after every set of transactions to save some power. 373 */ 374 struct clk *scb_clk, *sys_clk; 375 unsigned int bitrate; 376 bool need_wr_rd_fence; 377 378 /* state */ 379 struct completion msg_complete; 380 spinlock_t lock; /* lock before doing anything with the state */ 381 struct i2c_msg msg; 382 383 /* After the last transaction, wait for a stop bit */ 384 bool last_msg; 385 int msg_status; 386 387 enum img_i2c_mode mode; 388 u32 int_enable; /* depends on mode */ 389 u32 line_status; /* line status over command */ 390 391 /* 392 * To avoid slave event interrupts in automatic mode, use a timer to 393 * poll the abort condition if we don't get an interrupt for too long. 394 */ 395 struct timer_list check_timer; 396 bool t_halt; 397 398 /* atomic mode state */ 399 bool at_t_done; 400 bool at_slave_event; 401 int at_cur_cmd; 402 u8 at_cur_data; 403 404 /* Sequence: either reset or stop. See img_i2c_sequence. */ 405 u8 *seq; 406 407 /* raw mode */ 408 unsigned int raw_timeout; 409 }; 410 411 static int img_i2c_runtime_suspend(struct device *dev); 412 static int img_i2c_runtime_resume(struct device *dev); 413 414 static void img_i2c_writel(struct img_i2c *i2c, u32 offset, u32 value) 415 { 416 writel(value, i2c->base + offset); 417 } 418 419 static u32 img_i2c_readl(struct img_i2c *i2c, u32 offset) 420 { 421 return readl(i2c->base + offset); 422 } 423 424 /* 425 * The code to read from the master read fifo, and write to the master 426 * write fifo, checks a bit in an SCB register before every byte to 427 * ensure that the fifo is not full (write fifo) or empty (read fifo). 428 * Due to clock domain crossing inside the SCB block the updated value 429 * of this bit is only visible after 2 cycles. 430 * 431 * The scb_wr_rd_fence() function does 2 dummy writes (to the read-only 432 * revision register), and it's called after reading from or writing to the 433 * fifos to ensure that subsequent reads of the fifo status bits do not read 434 * stale values. 435 */ 436 static void img_i2c_wr_rd_fence(struct img_i2c *i2c) 437 { 438 if (i2c->need_wr_rd_fence) { 439 img_i2c_writel(i2c, SCB_CORE_REV_REG, 0); 440 img_i2c_writel(i2c, SCB_CORE_REV_REG, 0); 441 } 442 } 443 444 static void img_i2c_switch_mode(struct img_i2c *i2c, enum img_i2c_mode mode) 445 { 446 i2c->mode = mode; 447 i2c->int_enable = img_i2c_int_enable_by_mode[mode]; 448 i2c->line_status = 0; 449 } 450 451 static void img_i2c_raw_op(struct img_i2c *i2c) 452 { 453 i2c->raw_timeout = 0; 454 img_i2c_writel(i2c, SCB_OVERRIDE_REG, 455 OVERRIDE_SCLKEN_OVR | 456 OVERRIDE_SDATEN_OVR | 457 OVERRIDE_MASTER | 458 OVERRIDE_LINE_OVR_EN | 459 OVERRIDE_DIRECT | 460 ((i2c->at_cur_cmd & OVERRIDE_CMD_MASK) << OVERRIDE_CMD_SHIFT) | 461 (i2c->at_cur_data << OVERRIDE_DATA_SHIFT)); 462 } 463 464 static const char *img_i2c_atomic_op_name(unsigned int cmd) 465 { 466 if (unlikely(cmd >= ARRAY_SIZE(img_i2c_atomic_cmd_names))) 467 return "UNKNOWN"; 468 return img_i2c_atomic_cmd_names[cmd]; 469 } 470 471 /* Send a single atomic mode command to the hardware */ 472 static void img_i2c_atomic_op(struct img_i2c *i2c, int cmd, u8 data) 473 { 474 i2c->at_cur_cmd = cmd; 475 i2c->at_cur_data = data; 476 477 /* work around lack of data setup time when generating data */ 478 if (cmd == CMD_GEN_DATA && i2c->mode == MODE_ATOMIC) { 479 u32 line_status = img_i2c_readl(i2c, SCB_STATUS_REG); 480 481 if (line_status & LINESTAT_SDAT_LINE_STATUS && !(data & 0x80)) { 482 /* hold the data line down for a moment */ 483 img_i2c_switch_mode(i2c, MODE_RAW); 484 img_i2c_raw_op(i2c); 485 return; 486 } 487 } 488 489 dev_dbg(i2c->adap.dev.parent, 490 "atomic cmd=%s (%d) data=%#x\n", 491 img_i2c_atomic_op_name(cmd), cmd, data); 492 i2c->at_t_done = (cmd == CMD_RET_DATA || cmd == CMD_RET_ACK); 493 i2c->at_slave_event = false; 494 i2c->line_status = 0; 495 496 img_i2c_writel(i2c, SCB_OVERRIDE_REG, 497 ((cmd & OVERRIDE_CMD_MASK) << OVERRIDE_CMD_SHIFT) | 498 OVERRIDE_MASTER | 499 OVERRIDE_DIRECT | 500 (data << OVERRIDE_DATA_SHIFT)); 501 } 502 503 /* Start a transaction in atomic mode */ 504 static void img_i2c_atomic_start(struct img_i2c *i2c) 505 { 506 img_i2c_switch_mode(i2c, MODE_ATOMIC); 507 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 508 img_i2c_atomic_op(i2c, CMD_GEN_START, 0x00); 509 } 510 511 static void img_i2c_soft_reset(struct img_i2c *i2c) 512 { 513 i2c->t_halt = false; 514 img_i2c_writel(i2c, SCB_CONTROL_REG, 0); 515 img_i2c_writel(i2c, SCB_CONTROL_REG, 516 SCB_CONTROL_CLK_ENABLE | SCB_CONTROL_SOFT_RESET); 517 } 518 519 /* 520 * Enable or release transaction halt for control of repeated starts. 521 * In version 3.3 of the IP when transaction halt is set, an interrupt 522 * will be generated after each byte of a transfer instead of after 523 * every transfer but before the stop bit. 524 * Due to this behaviour we have to be careful that every time we 525 * release the transaction halt we have to re-enable it straight away 526 * so that we only process a single byte, not doing so will result in 527 * all remaining bytes been processed and a stop bit being issued, 528 * which will prevent us having a repeated start. 529 */ 530 static void img_i2c_transaction_halt(struct img_i2c *i2c, bool t_halt) 531 { 532 u32 val; 533 534 if (i2c->t_halt == t_halt) 535 return; 536 i2c->t_halt = t_halt; 537 val = img_i2c_readl(i2c, SCB_CONTROL_REG); 538 if (t_halt) 539 val |= SCB_CONTROL_TRANSACTION_HALT; 540 else 541 val &= ~SCB_CONTROL_TRANSACTION_HALT; 542 img_i2c_writel(i2c, SCB_CONTROL_REG, val); 543 } 544 545 /* Drain data from the FIFO into the buffer (automatic mode) */ 546 static void img_i2c_read_fifo(struct img_i2c *i2c) 547 { 548 while (i2c->msg.len) { 549 u32 fifo_status; 550 u8 data; 551 552 img_i2c_wr_rd_fence(i2c); 553 fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG); 554 if (fifo_status & FIFO_READ_EMPTY) 555 break; 556 557 data = img_i2c_readl(i2c, SCB_READ_DATA_REG); 558 *i2c->msg.buf = data; 559 560 img_i2c_writel(i2c, SCB_READ_FIFO_REG, 0xff); 561 i2c->msg.len--; 562 i2c->msg.buf++; 563 } 564 } 565 566 /* Fill the FIFO with data from the buffer (automatic mode) */ 567 static void img_i2c_write_fifo(struct img_i2c *i2c) 568 { 569 while (i2c->msg.len) { 570 u32 fifo_status; 571 572 img_i2c_wr_rd_fence(i2c); 573 fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG); 574 if (fifo_status & FIFO_WRITE_FULL) 575 break; 576 577 img_i2c_writel(i2c, SCB_WRITE_DATA_REG, *i2c->msg.buf); 578 i2c->msg.len--; 579 i2c->msg.buf++; 580 } 581 582 /* Disable fifo emptying interrupt if nothing more to write */ 583 if (!i2c->msg.len) 584 i2c->int_enable &= ~INT_FIFO_EMPTYING; 585 } 586 587 /* Start a read transaction in automatic mode */ 588 static void img_i2c_read(struct img_i2c *i2c) 589 { 590 img_i2c_switch_mode(i2c, MODE_AUTOMATIC); 591 if (!i2c->last_msg) 592 i2c->int_enable |= INT_SLAVE_EVENT; 593 594 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 595 img_i2c_writel(i2c, SCB_READ_ADDR_REG, i2c->msg.addr); 596 img_i2c_writel(i2c, SCB_READ_COUNT_REG, i2c->msg.len); 597 598 mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1)); 599 } 600 601 /* Start a write transaction in automatic mode */ 602 static void img_i2c_write(struct img_i2c *i2c) 603 { 604 img_i2c_switch_mode(i2c, MODE_AUTOMATIC); 605 if (!i2c->last_msg) 606 i2c->int_enable |= INT_SLAVE_EVENT; 607 608 img_i2c_writel(i2c, SCB_WRITE_ADDR_REG, i2c->msg.addr); 609 img_i2c_writel(i2c, SCB_WRITE_COUNT_REG, i2c->msg.len); 610 611 mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1)); 612 img_i2c_write_fifo(i2c); 613 614 /* img_i2c_write_fifo() may modify int_enable */ 615 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 616 } 617 618 /* 619 * Indicate that the transaction is complete. This is called from the 620 * ISR to wake up the waiting thread, after which the ISR must not 621 * access any more SCB registers. 622 */ 623 static void img_i2c_complete_transaction(struct img_i2c *i2c, int status) 624 { 625 img_i2c_switch_mode(i2c, MODE_INACTIVE); 626 if (status) { 627 i2c->msg_status = status; 628 img_i2c_transaction_halt(i2c, false); 629 } 630 complete(&i2c->msg_complete); 631 } 632 633 static unsigned int img_i2c_raw_atomic_delay_handler(struct img_i2c *i2c, 634 u32 int_status, u32 line_status) 635 { 636 /* Stay in raw mode for this, so we don't just loop infinitely */ 637 img_i2c_atomic_op(i2c, i2c->at_cur_cmd, i2c->at_cur_data); 638 img_i2c_switch_mode(i2c, MODE_ATOMIC); 639 return 0; 640 } 641 642 static unsigned int img_i2c_raw(struct img_i2c *i2c, u32 int_status, 643 u32 line_status) 644 { 645 if (int_status & INT_TIMING) { 646 if (i2c->raw_timeout == 0) 647 return img_i2c_raw_atomic_delay_handler(i2c, 648 int_status, line_status); 649 --i2c->raw_timeout; 650 } 651 return 0; 652 } 653 654 static unsigned int img_i2c_sequence(struct img_i2c *i2c, u32 int_status) 655 { 656 static const unsigned int continue_bits[] = { 657 [CMD_GEN_START] = LINESTAT_START_BIT_DET, 658 [CMD_GEN_DATA] = LINESTAT_INPUT_HELD_V, 659 [CMD_RET_ACK] = LINESTAT_ACK_DET | LINESTAT_NACK_DET, 660 [CMD_RET_DATA] = LINESTAT_INPUT_HELD_V, 661 [CMD_GEN_STOP] = LINESTAT_STOP_BIT_DET, 662 }; 663 int next_cmd = -1; 664 u8 next_data = 0x00; 665 666 if (int_status & INT_SLAVE_EVENT) 667 i2c->at_slave_event = true; 668 if (int_status & INT_TRANSACTION_DONE) 669 i2c->at_t_done = true; 670 671 if (!i2c->at_slave_event || !i2c->at_t_done) 672 return 0; 673 674 /* wait if no continue bits are set */ 675 if (i2c->at_cur_cmd >= 0 && 676 i2c->at_cur_cmd < ARRAY_SIZE(continue_bits)) { 677 unsigned int cont_bits = continue_bits[i2c->at_cur_cmd]; 678 679 if (cont_bits) { 680 cont_bits |= LINESTAT_ABORT_DET; 681 if (!(i2c->line_status & cont_bits)) 682 return 0; 683 } 684 } 685 686 /* follow the sequence of commands in i2c->seq */ 687 next_cmd = *i2c->seq; 688 /* stop on a nil */ 689 if (!next_cmd) { 690 img_i2c_writel(i2c, SCB_OVERRIDE_REG, 0); 691 return ISR_COMPLETE(0); 692 } 693 /* when generating data, the next byte is the data */ 694 if (next_cmd == CMD_GEN_DATA) { 695 ++i2c->seq; 696 next_data = *i2c->seq; 697 } 698 ++i2c->seq; 699 img_i2c_atomic_op(i2c, next_cmd, next_data); 700 701 return 0; 702 } 703 704 static void img_i2c_reset_start(struct img_i2c *i2c) 705 { 706 /* Initiate the magic dance */ 707 img_i2c_switch_mode(i2c, MODE_SEQUENCE); 708 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 709 i2c->seq = img_i2c_reset_seq; 710 i2c->at_slave_event = true; 711 i2c->at_t_done = true; 712 i2c->at_cur_cmd = -1; 713 714 /* img_i2c_reset_seq isn't empty so the following won't fail */ 715 img_i2c_sequence(i2c, 0); 716 } 717 718 static void img_i2c_stop_start(struct img_i2c *i2c) 719 { 720 /* Initiate a stop bit sequence */ 721 img_i2c_switch_mode(i2c, MODE_SEQUENCE); 722 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 723 i2c->seq = img_i2c_stop_seq; 724 i2c->at_slave_event = true; 725 i2c->at_t_done = true; 726 i2c->at_cur_cmd = -1; 727 728 /* img_i2c_stop_seq isn't empty so the following won't fail */ 729 img_i2c_sequence(i2c, 0); 730 } 731 732 static unsigned int img_i2c_atomic(struct img_i2c *i2c, 733 u32 int_status, 734 u32 line_status) 735 { 736 int next_cmd = -1; 737 u8 next_data = 0x00; 738 739 if (int_status & INT_SLAVE_EVENT) 740 i2c->at_slave_event = true; 741 if (int_status & INT_TRANSACTION_DONE) 742 i2c->at_t_done = true; 743 744 if (!i2c->at_slave_event || !i2c->at_t_done) 745 goto next_atomic_cmd; 746 if (i2c->line_status & LINESTAT_ABORT_DET) { 747 dev_dbg(i2c->adap.dev.parent, "abort condition detected\n"); 748 next_cmd = CMD_GEN_STOP; 749 i2c->msg_status = -EIO; 750 goto next_atomic_cmd; 751 } 752 753 /* i2c->at_cur_cmd may have completed */ 754 switch (i2c->at_cur_cmd) { 755 case CMD_GEN_START: 756 next_cmd = CMD_GEN_DATA; 757 next_data = i2c_8bit_addr_from_msg(&i2c->msg); 758 break; 759 case CMD_GEN_DATA: 760 if (i2c->line_status & LINESTAT_INPUT_HELD_V) 761 next_cmd = CMD_RET_ACK; 762 break; 763 case CMD_RET_ACK: 764 if (i2c->line_status & LINESTAT_ACK_DET || 765 (i2c->line_status & LINESTAT_NACK_DET && 766 i2c->msg.flags & I2C_M_IGNORE_NAK)) { 767 if (i2c->msg.len == 0) { 768 next_cmd = CMD_GEN_STOP; 769 } else if (i2c->msg.flags & I2C_M_RD) { 770 next_cmd = CMD_RET_DATA; 771 } else { 772 next_cmd = CMD_GEN_DATA; 773 next_data = *i2c->msg.buf; 774 --i2c->msg.len; 775 ++i2c->msg.buf; 776 } 777 } else if (i2c->line_status & LINESTAT_NACK_DET) { 778 i2c->msg_status = -EIO; 779 next_cmd = CMD_GEN_STOP; 780 } 781 break; 782 case CMD_RET_DATA: 783 if (i2c->line_status & LINESTAT_INPUT_HELD_V) { 784 *i2c->msg.buf = (i2c->line_status & 785 LINESTAT_INPUT_DATA) 786 >> LINESTAT_INPUT_DATA_SHIFT; 787 --i2c->msg.len; 788 ++i2c->msg.buf; 789 if (i2c->msg.len) 790 next_cmd = CMD_GEN_ACK; 791 else 792 next_cmd = CMD_GEN_NACK; 793 } 794 break; 795 case CMD_GEN_ACK: 796 if (i2c->line_status & LINESTAT_ACK_DET) { 797 next_cmd = CMD_RET_DATA; 798 } else { 799 i2c->msg_status = -EIO; 800 next_cmd = CMD_GEN_STOP; 801 } 802 break; 803 case CMD_GEN_NACK: 804 next_cmd = CMD_GEN_STOP; 805 break; 806 case CMD_GEN_STOP: 807 img_i2c_writel(i2c, SCB_OVERRIDE_REG, 0); 808 return ISR_COMPLETE(0); 809 default: 810 dev_err(i2c->adap.dev.parent, "bad atomic command %d\n", 811 i2c->at_cur_cmd); 812 i2c->msg_status = -EIO; 813 next_cmd = CMD_GEN_STOP; 814 break; 815 } 816 817 next_atomic_cmd: 818 if (next_cmd != -1) { 819 /* don't actually stop unless we're the last transaction */ 820 if (next_cmd == CMD_GEN_STOP && !i2c->msg_status && 821 !i2c->last_msg) 822 return ISR_COMPLETE(0); 823 img_i2c_atomic_op(i2c, next_cmd, next_data); 824 } 825 return 0; 826 } 827 828 /* 829 * Timer function to check if something has gone wrong in automatic mode (so we 830 * don't have to handle so many interrupts just to catch an exception). 831 */ 832 static void img_i2c_check_timer(struct timer_list *t) 833 { 834 struct img_i2c *i2c = from_timer(i2c, t, check_timer); 835 unsigned long flags; 836 unsigned int line_status; 837 838 spin_lock_irqsave(&i2c->lock, flags); 839 line_status = img_i2c_readl(i2c, SCB_STATUS_REG); 840 841 /* check for an abort condition */ 842 if (line_status & LINESTAT_ABORT_DET) { 843 dev_dbg(i2c->adap.dev.parent, 844 "abort condition detected by check timer\n"); 845 /* enable slave event interrupt mask to trigger irq */ 846 img_i2c_writel(i2c, SCB_INT_MASK_REG, 847 i2c->int_enable | INT_SLAVE_EVENT); 848 } 849 850 spin_unlock_irqrestore(&i2c->lock, flags); 851 } 852 853 static unsigned int img_i2c_auto(struct img_i2c *i2c, 854 unsigned int int_status, 855 unsigned int line_status) 856 { 857 if (int_status & (INT_WRITE_ACK_ERR | INT_ADDR_ACK_ERR)) 858 return ISR_COMPLETE(EIO); 859 860 if (line_status & LINESTAT_ABORT_DET) { 861 dev_dbg(i2c->adap.dev.parent, "abort condition detected\n"); 862 /* empty the read fifo */ 863 if ((i2c->msg.flags & I2C_M_RD) && 864 (int_status & INT_FIFO_FULL_FILLING)) 865 img_i2c_read_fifo(i2c); 866 /* use atomic mode and try to force a stop bit */ 867 i2c->msg_status = -EIO; 868 img_i2c_stop_start(i2c); 869 return 0; 870 } 871 872 /* Enable transaction halt on start bit */ 873 if (!i2c->last_msg && line_status & LINESTAT_START_BIT_DET) { 874 img_i2c_transaction_halt(i2c, !i2c->last_msg); 875 /* we're no longer interested in the slave event */ 876 i2c->int_enable &= ~INT_SLAVE_EVENT; 877 } 878 879 mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1)); 880 881 if (int_status & INT_STOP_DETECTED) { 882 /* Drain remaining data in FIFO and complete transaction */ 883 if (i2c->msg.flags & I2C_M_RD) 884 img_i2c_read_fifo(i2c); 885 return ISR_COMPLETE(0); 886 } 887 888 if (i2c->msg.flags & I2C_M_RD) { 889 if (int_status & (INT_FIFO_FULL_FILLING | INT_MASTER_HALTED)) { 890 img_i2c_read_fifo(i2c); 891 if (i2c->msg.len == 0) 892 return ISR_WAITSTOP; 893 } 894 } else { 895 if (int_status & (INT_FIFO_EMPTY | INT_MASTER_HALTED)) { 896 if ((int_status & INT_FIFO_EMPTY) && 897 i2c->msg.len == 0) 898 return ISR_WAITSTOP; 899 img_i2c_write_fifo(i2c); 900 } 901 } 902 if (int_status & INT_MASTER_HALTED) { 903 /* 904 * Release and then enable transaction halt, to 905 * allow only a single byte to proceed. 906 */ 907 img_i2c_transaction_halt(i2c, false); 908 img_i2c_transaction_halt(i2c, !i2c->last_msg); 909 } 910 911 return 0; 912 } 913 914 static irqreturn_t img_i2c_isr(int irq, void *dev_id) 915 { 916 struct img_i2c *i2c = dev_id; 917 u32 int_status, line_status; 918 /* We handle transaction completion AFTER accessing registers */ 919 unsigned int hret; 920 921 /* Read interrupt status register. */ 922 int_status = img_i2c_readl(i2c, SCB_INT_STATUS_REG); 923 /* Clear detected interrupts. */ 924 img_i2c_writel(i2c, SCB_INT_CLEAR_REG, int_status); 925 926 /* 927 * Read line status and clear it until it actually is clear. We have 928 * to be careful not to lose any line status bits that get latched. 929 */ 930 line_status = img_i2c_readl(i2c, SCB_STATUS_REG); 931 if (line_status & LINESTAT_LATCHED) { 932 img_i2c_writel(i2c, SCB_CLEAR_REG, 933 (line_status & LINESTAT_LATCHED) 934 >> LINESTAT_CLEAR_SHIFT); 935 img_i2c_wr_rd_fence(i2c); 936 } 937 938 spin_lock(&i2c->lock); 939 940 /* Keep track of line status bits received */ 941 i2c->line_status &= ~LINESTAT_INPUT_DATA; 942 i2c->line_status |= line_status; 943 944 /* 945 * Certain interrupts indicate that sclk low timeout is not 946 * a problem. If any of these are set, just continue. 947 */ 948 if ((int_status & INT_SCLK_LOW_TIMEOUT) && 949 !(int_status & (INT_SLAVE_EVENT | 950 INT_FIFO_EMPTY | 951 INT_FIFO_FULL))) { 952 dev_crit(i2c->adap.dev.parent, 953 "fatal: clock low timeout occurred %s addr 0x%02x\n", 954 (i2c->msg.flags & I2C_M_RD) ? "reading" : "writing", 955 i2c->msg.addr); 956 hret = ISR_FATAL(EIO); 957 goto out; 958 } 959 960 if (i2c->mode == MODE_ATOMIC) 961 hret = img_i2c_atomic(i2c, int_status, line_status); 962 else if (i2c->mode == MODE_AUTOMATIC) 963 hret = img_i2c_auto(i2c, int_status, line_status); 964 else if (i2c->mode == MODE_SEQUENCE) 965 hret = img_i2c_sequence(i2c, int_status); 966 else if (i2c->mode == MODE_WAITSTOP && (int_status & INT_SLAVE_EVENT) && 967 (line_status & LINESTAT_STOP_BIT_DET)) 968 hret = ISR_COMPLETE(0); 969 else if (i2c->mode == MODE_RAW) 970 hret = img_i2c_raw(i2c, int_status, line_status); 971 else 972 hret = 0; 973 974 /* Clear detected level interrupts. */ 975 img_i2c_writel(i2c, SCB_INT_CLEAR_REG, int_status & INT_LEVEL); 976 977 out: 978 if (hret & ISR_WAITSTOP) { 979 /* 980 * Only wait for stop on last message. 981 * Also we may already have detected the stop bit. 982 */ 983 if (!i2c->last_msg || i2c->line_status & LINESTAT_STOP_BIT_DET) 984 hret = ISR_COMPLETE(0); 985 else 986 img_i2c_switch_mode(i2c, MODE_WAITSTOP); 987 } 988 989 /* now we've finished using regs, handle transaction completion */ 990 if (hret & ISR_COMPLETE_M) { 991 int status = -(hret & ISR_STATUS_M); 992 993 img_i2c_complete_transaction(i2c, status); 994 if (hret & ISR_FATAL_M) 995 img_i2c_switch_mode(i2c, MODE_FATAL); 996 } 997 998 /* Enable interrupts (int_enable may be altered by changing mode) */ 999 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 1000 1001 spin_unlock(&i2c->lock); 1002 1003 return IRQ_HANDLED; 1004 } 1005 1006 /* Force a bus reset sequence and wait for it to complete */ 1007 static int img_i2c_reset_bus(struct img_i2c *i2c) 1008 { 1009 unsigned long flags; 1010 unsigned long time_left; 1011 1012 spin_lock_irqsave(&i2c->lock, flags); 1013 reinit_completion(&i2c->msg_complete); 1014 img_i2c_reset_start(i2c); 1015 spin_unlock_irqrestore(&i2c->lock, flags); 1016 1017 time_left = wait_for_completion_timeout(&i2c->msg_complete, 1018 IMG_I2C_TIMEOUT); 1019 if (time_left == 0) 1020 return -ETIMEDOUT; 1021 return 0; 1022 } 1023 1024 static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, 1025 int num) 1026 { 1027 struct img_i2c *i2c = i2c_get_adapdata(adap); 1028 bool atomic = false; 1029 int i, ret; 1030 unsigned long time_left; 1031 1032 if (i2c->mode == MODE_SUSPEND) { 1033 WARN(1, "refusing to service transaction in suspended state\n"); 1034 return -EIO; 1035 } 1036 1037 if (i2c->mode == MODE_FATAL) 1038 return -EIO; 1039 1040 for (i = 0; i < num; i++) { 1041 /* 1042 * 0 byte reads are not possible because the slave could try 1043 * and pull the data line low, preventing a stop bit. 1044 */ 1045 if (!msgs[i].len && msgs[i].flags & I2C_M_RD) 1046 return -EIO; 1047 /* 1048 * 0 byte writes are possible and used for probing, but we 1049 * cannot do them in automatic mode, so use atomic mode 1050 * instead. 1051 * 1052 * Also, the I2C_M_IGNORE_NAK mode can only be implemented 1053 * in atomic mode. 1054 */ 1055 if (!msgs[i].len || 1056 (msgs[i].flags & I2C_M_IGNORE_NAK)) 1057 atomic = true; 1058 } 1059 1060 ret = pm_runtime_resume_and_get(adap->dev.parent); 1061 if (ret < 0) 1062 return ret; 1063 1064 for (i = 0; i < num; i++) { 1065 struct i2c_msg *msg = &msgs[i]; 1066 unsigned long flags; 1067 1068 spin_lock_irqsave(&i2c->lock, flags); 1069 1070 /* 1071 * Make a copy of the message struct. We mustn't modify the 1072 * original or we'll confuse drivers and i2c-dev. 1073 */ 1074 i2c->msg = *msg; 1075 i2c->msg_status = 0; 1076 1077 /* 1078 * After the last message we must have waited for a stop bit. 1079 * Not waiting can cause problems when the clock is disabled 1080 * before the stop bit is sent, and the linux I2C interface 1081 * requires separate transfers not to joined with repeated 1082 * start. 1083 */ 1084 i2c->last_msg = (i == num - 1); 1085 reinit_completion(&i2c->msg_complete); 1086 1087 /* 1088 * Clear line status and all interrupts before starting a 1089 * transfer, as we may have unserviced interrupts from 1090 * previous transfers that might be handled in the context 1091 * of the new transfer. 1092 */ 1093 img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0); 1094 img_i2c_writel(i2c, SCB_CLEAR_REG, ~0); 1095 1096 if (atomic) { 1097 img_i2c_atomic_start(i2c); 1098 } else { 1099 /* 1100 * Enable transaction halt if not the last message in 1101 * the queue so that we can control repeated starts. 1102 */ 1103 img_i2c_transaction_halt(i2c, !i2c->last_msg); 1104 1105 if (msg->flags & I2C_M_RD) 1106 img_i2c_read(i2c); 1107 else 1108 img_i2c_write(i2c); 1109 1110 /* 1111 * Release and then enable transaction halt, to 1112 * allow only a single byte to proceed. 1113 * This doesn't have an effect on the initial transfer 1114 * but will allow the following transfers to start 1115 * processing if the previous transfer was marked as 1116 * complete while the i2c block was halted. 1117 */ 1118 img_i2c_transaction_halt(i2c, false); 1119 img_i2c_transaction_halt(i2c, !i2c->last_msg); 1120 } 1121 spin_unlock_irqrestore(&i2c->lock, flags); 1122 1123 time_left = wait_for_completion_timeout(&i2c->msg_complete, 1124 IMG_I2C_TIMEOUT); 1125 del_timer_sync(&i2c->check_timer); 1126 1127 if (time_left == 0) { 1128 dev_err(adap->dev.parent, "i2c transfer timed out\n"); 1129 i2c->msg_status = -ETIMEDOUT; 1130 break; 1131 } 1132 1133 if (i2c->msg_status) 1134 break; 1135 } 1136 1137 pm_runtime_mark_last_busy(adap->dev.parent); 1138 pm_runtime_put_autosuspend(adap->dev.parent); 1139 1140 return i2c->msg_status ? i2c->msg_status : num; 1141 } 1142 1143 static u32 img_i2c_func(struct i2c_adapter *adap) 1144 { 1145 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 1146 } 1147 1148 static const struct i2c_algorithm img_i2c_algo = { 1149 .master_xfer = img_i2c_xfer, 1150 .functionality = img_i2c_func, 1151 }; 1152 1153 static int img_i2c_init(struct img_i2c *i2c) 1154 { 1155 unsigned int clk_khz, bitrate_khz, clk_period, tckh, tckl, tsdh; 1156 unsigned int i, data, prescale, inc, int_bitrate, filt; 1157 struct img_i2c_timings timing; 1158 u32 rev; 1159 int ret; 1160 1161 ret = pm_runtime_resume_and_get(i2c->adap.dev.parent); 1162 if (ret < 0) 1163 return ret; 1164 1165 rev = img_i2c_readl(i2c, SCB_CORE_REV_REG); 1166 if ((rev & 0x00ffffff) < 0x00020200) { 1167 dev_info(i2c->adap.dev.parent, 1168 "Unknown hardware revision (%d.%d.%d.%d)\n", 1169 (rev >> 24) & 0xff, (rev >> 16) & 0xff, 1170 (rev >> 8) & 0xff, rev & 0xff); 1171 pm_runtime_mark_last_busy(i2c->adap.dev.parent); 1172 pm_runtime_put_autosuspend(i2c->adap.dev.parent); 1173 return -EINVAL; 1174 } 1175 1176 /* Fencing enabled by default. */ 1177 i2c->need_wr_rd_fence = true; 1178 1179 /* Determine what mode we're in from the bitrate */ 1180 timing = timings[0]; 1181 for (i = 0; i < ARRAY_SIZE(timings); i++) { 1182 if (i2c->bitrate <= timings[i].max_bitrate) { 1183 timing = timings[i]; 1184 break; 1185 } 1186 } 1187 if (i2c->bitrate > timings[ARRAY_SIZE(timings) - 1].max_bitrate) { 1188 dev_warn(i2c->adap.dev.parent, 1189 "requested bitrate (%u) is higher than the max bitrate supported (%u)\n", 1190 i2c->bitrate, 1191 timings[ARRAY_SIZE(timings) - 1].max_bitrate); 1192 timing = timings[ARRAY_SIZE(timings) - 1]; 1193 i2c->bitrate = timing.max_bitrate; 1194 } 1195 1196 bitrate_khz = i2c->bitrate / 1000; 1197 clk_khz = clk_get_rate(i2c->scb_clk) / 1000; 1198 1199 /* Find the prescale that would give us that inc (approx delay = 0) */ 1200 prescale = SCB_OPT_INC * clk_khz / (256 * 16 * bitrate_khz); 1201 prescale = clamp_t(unsigned int, prescale, 1, 8); 1202 clk_khz /= prescale; 1203 1204 /* Setup the clock increment value */ 1205 inc = (256 * 16 * bitrate_khz) / clk_khz; 1206 1207 /* 1208 * The clock generation logic allows to filter glitches on the bus. 1209 * This filter is able to remove bus glitches shorter than 50ns. 1210 * If the clock enable rate is greater than 20 MHz, no filtering 1211 * is required, so we need to disable it. 1212 * If it's between the 20-40 MHz range, there's no need to divide 1213 * the clock to get a filter. 1214 */ 1215 if (clk_khz < 20000) { 1216 filt = SCB_FILT_DISABLE; 1217 } else if (clk_khz < 40000) { 1218 filt = SCB_FILT_BYPASS; 1219 } else { 1220 /* Calculate filter clock */ 1221 filt = (64000 / ((clk_khz / 1000) * SCB_FILT_GLITCH)); 1222 1223 /* Scale up if needed */ 1224 if (64000 % ((clk_khz / 1000) * SCB_FILT_GLITCH)) 1225 inc++; 1226 1227 if (filt > SCB_FILT_INC_MASK) 1228 filt = SCB_FILT_INC_MASK; 1229 1230 filt = (filt & SCB_FILT_INC_MASK) << SCB_FILT_INC_SHIFT; 1231 } 1232 data = filt | ((inc & SCB_INC_MASK) << SCB_INC_SHIFT) | (prescale - 1); 1233 img_i2c_writel(i2c, SCB_CLK_SET_REG, data); 1234 1235 /* Obtain the clock period of the fx16 clock in ns */ 1236 clk_period = (256 * 1000000) / (clk_khz * inc); 1237 1238 /* Calculate the bitrate in terms of internal clock pulses */ 1239 int_bitrate = 1000000 / (bitrate_khz * clk_period); 1240 if ((1000000 % (bitrate_khz * clk_period)) >= 1241 ((bitrate_khz * clk_period) / 2)) 1242 int_bitrate++; 1243 1244 /* 1245 * Setup clock duty cycle, start with 50% and adjust TCKH and TCKL 1246 * values from there if they don't meet minimum timing requirements 1247 */ 1248 tckh = int_bitrate / 2; 1249 tckl = int_bitrate - tckh; 1250 1251 /* Adjust TCKH and TCKL values */ 1252 data = DIV_ROUND_UP(timing.tckl, clk_period); 1253 1254 if (tckl < data) { 1255 tckl = data; 1256 tckh = int_bitrate - tckl; 1257 } 1258 1259 if (tckh > 0) 1260 --tckh; 1261 1262 if (tckl > 0) 1263 --tckl; 1264 1265 img_i2c_writel(i2c, SCB_TIME_TCKH_REG, tckh); 1266 img_i2c_writel(i2c, SCB_TIME_TCKL_REG, tckl); 1267 1268 /* Setup TSDH value */ 1269 tsdh = DIV_ROUND_UP(timing.tsdh, clk_period); 1270 1271 if (tsdh > 1) 1272 data = tsdh - 1; 1273 else 1274 data = 0x01; 1275 img_i2c_writel(i2c, SCB_TIME_TSDH_REG, data); 1276 1277 /* This value is used later */ 1278 tsdh = data; 1279 1280 /* Setup TPL value */ 1281 data = timing.tpl / clk_period; 1282 if (data > 0) 1283 --data; 1284 img_i2c_writel(i2c, SCB_TIME_TPL_REG, data); 1285 1286 /* Setup TPH value */ 1287 data = timing.tph / clk_period; 1288 if (data > 0) 1289 --data; 1290 img_i2c_writel(i2c, SCB_TIME_TPH_REG, data); 1291 1292 /* Setup TSDL value to TPL + TSDH + 2 */ 1293 img_i2c_writel(i2c, SCB_TIME_TSDL_REG, data + tsdh + 2); 1294 1295 /* Setup TP2S value */ 1296 data = timing.tp2s / clk_period; 1297 if (data > 0) 1298 --data; 1299 img_i2c_writel(i2c, SCB_TIME_TP2S_REG, data); 1300 1301 img_i2c_writel(i2c, SCB_TIME_TBI_REG, TIMEOUT_TBI); 1302 img_i2c_writel(i2c, SCB_TIME_TSL_REG, TIMEOUT_TSL); 1303 img_i2c_writel(i2c, SCB_TIME_TDL_REG, TIMEOUT_TDL); 1304 1305 /* Take module out of soft reset and enable clocks */ 1306 img_i2c_soft_reset(i2c); 1307 1308 /* Disable all interrupts */ 1309 img_i2c_writel(i2c, SCB_INT_MASK_REG, 0); 1310 1311 /* Clear all interrupts */ 1312 img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0); 1313 1314 /* Clear the scb_line_status events */ 1315 img_i2c_writel(i2c, SCB_CLEAR_REG, ~0); 1316 1317 /* Enable interrupts */ 1318 img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable); 1319 1320 /* Perform a synchronous sequence to reset the bus */ 1321 ret = img_i2c_reset_bus(i2c); 1322 1323 pm_runtime_mark_last_busy(i2c->adap.dev.parent); 1324 pm_runtime_put_autosuspend(i2c->adap.dev.parent); 1325 1326 return ret; 1327 } 1328 1329 static int img_i2c_probe(struct platform_device *pdev) 1330 { 1331 struct device_node *node = pdev->dev.of_node; 1332 struct img_i2c *i2c; 1333 int irq, ret; 1334 u32 val; 1335 1336 i2c = devm_kzalloc(&pdev->dev, sizeof(struct img_i2c), GFP_KERNEL); 1337 if (!i2c) 1338 return -ENOMEM; 1339 1340 i2c->base = devm_platform_ioremap_resource(pdev, 0); 1341 if (IS_ERR(i2c->base)) 1342 return PTR_ERR(i2c->base); 1343 1344 irq = platform_get_irq(pdev, 0); 1345 if (irq < 0) 1346 return irq; 1347 1348 i2c->sys_clk = devm_clk_get(&pdev->dev, "sys"); 1349 if (IS_ERR(i2c->sys_clk)) { 1350 dev_err(&pdev->dev, "can't get system clock\n"); 1351 return PTR_ERR(i2c->sys_clk); 1352 } 1353 1354 i2c->scb_clk = devm_clk_get(&pdev->dev, "scb"); 1355 if (IS_ERR(i2c->scb_clk)) { 1356 dev_err(&pdev->dev, "can't get core clock\n"); 1357 return PTR_ERR(i2c->scb_clk); 1358 } 1359 1360 ret = devm_request_irq(&pdev->dev, irq, img_i2c_isr, 0, 1361 pdev->name, i2c); 1362 if (ret) { 1363 dev_err(&pdev->dev, "can't request irq %d\n", irq); 1364 return ret; 1365 } 1366 1367 /* Set up the exception check timer */ 1368 timer_setup(&i2c->check_timer, img_i2c_check_timer, 0); 1369 1370 i2c->bitrate = timings[0].max_bitrate; 1371 if (!of_property_read_u32(node, "clock-frequency", &val)) 1372 i2c->bitrate = val; 1373 1374 i2c_set_adapdata(&i2c->adap, i2c); 1375 i2c->adap.dev.parent = &pdev->dev; 1376 i2c->adap.dev.of_node = node; 1377 i2c->adap.owner = THIS_MODULE; 1378 i2c->adap.algo = &img_i2c_algo; 1379 i2c->adap.retries = 5; 1380 i2c->adap.nr = pdev->id; 1381 snprintf(i2c->adap.name, sizeof(i2c->adap.name), "IMG SCB I2C"); 1382 1383 img_i2c_switch_mode(i2c, MODE_INACTIVE); 1384 spin_lock_init(&i2c->lock); 1385 init_completion(&i2c->msg_complete); 1386 1387 platform_set_drvdata(pdev, i2c); 1388 1389 pm_runtime_set_autosuspend_delay(&pdev->dev, IMG_I2C_PM_TIMEOUT); 1390 pm_runtime_use_autosuspend(&pdev->dev); 1391 pm_runtime_enable(&pdev->dev); 1392 if (!pm_runtime_enabled(&pdev->dev)) { 1393 ret = img_i2c_runtime_resume(&pdev->dev); 1394 if (ret) 1395 return ret; 1396 } 1397 1398 ret = img_i2c_init(i2c); 1399 if (ret) 1400 goto rpm_disable; 1401 1402 ret = i2c_add_numbered_adapter(&i2c->adap); 1403 if (ret < 0) 1404 goto rpm_disable; 1405 1406 return 0; 1407 1408 rpm_disable: 1409 if (!pm_runtime_enabled(&pdev->dev)) 1410 img_i2c_runtime_suspend(&pdev->dev); 1411 pm_runtime_disable(&pdev->dev); 1412 pm_runtime_dont_use_autosuspend(&pdev->dev); 1413 return ret; 1414 } 1415 1416 static void img_i2c_remove(struct platform_device *dev) 1417 { 1418 struct img_i2c *i2c = platform_get_drvdata(dev); 1419 1420 i2c_del_adapter(&i2c->adap); 1421 pm_runtime_disable(&dev->dev); 1422 if (!pm_runtime_status_suspended(&dev->dev)) 1423 img_i2c_runtime_suspend(&dev->dev); 1424 } 1425 1426 static int img_i2c_runtime_suspend(struct device *dev) 1427 { 1428 struct img_i2c *i2c = dev_get_drvdata(dev); 1429 1430 clk_disable_unprepare(i2c->scb_clk); 1431 clk_disable_unprepare(i2c->sys_clk); 1432 1433 return 0; 1434 } 1435 1436 static int img_i2c_runtime_resume(struct device *dev) 1437 { 1438 struct img_i2c *i2c = dev_get_drvdata(dev); 1439 int ret; 1440 1441 ret = clk_prepare_enable(i2c->sys_clk); 1442 if (ret) { 1443 dev_err(dev, "Unable to enable sys clock\n"); 1444 return ret; 1445 } 1446 1447 ret = clk_prepare_enable(i2c->scb_clk); 1448 if (ret) { 1449 dev_err(dev, "Unable to enable scb clock\n"); 1450 clk_disable_unprepare(i2c->sys_clk); 1451 return ret; 1452 } 1453 1454 return 0; 1455 } 1456 1457 #ifdef CONFIG_PM_SLEEP 1458 static int img_i2c_suspend(struct device *dev) 1459 { 1460 struct img_i2c *i2c = dev_get_drvdata(dev); 1461 int ret; 1462 1463 ret = pm_runtime_force_suspend(dev); 1464 if (ret) 1465 return ret; 1466 1467 img_i2c_switch_mode(i2c, MODE_SUSPEND); 1468 1469 return 0; 1470 } 1471 1472 static int img_i2c_resume(struct device *dev) 1473 { 1474 struct img_i2c *i2c = dev_get_drvdata(dev); 1475 int ret; 1476 1477 ret = pm_runtime_force_resume(dev); 1478 if (ret) 1479 return ret; 1480 1481 img_i2c_init(i2c); 1482 1483 return 0; 1484 } 1485 #endif /* CONFIG_PM_SLEEP */ 1486 1487 static const struct dev_pm_ops img_i2c_pm = { 1488 SET_RUNTIME_PM_OPS(img_i2c_runtime_suspend, 1489 img_i2c_runtime_resume, 1490 NULL) 1491 SET_SYSTEM_SLEEP_PM_OPS(img_i2c_suspend, img_i2c_resume) 1492 }; 1493 1494 static const struct of_device_id img_scb_i2c_match[] = { 1495 { .compatible = "img,scb-i2c" }, 1496 { } 1497 }; 1498 MODULE_DEVICE_TABLE(of, img_scb_i2c_match); 1499 1500 static struct platform_driver img_scb_i2c_driver = { 1501 .driver = { 1502 .name = "img-i2c-scb", 1503 .of_match_table = img_scb_i2c_match, 1504 .pm = &img_i2c_pm, 1505 }, 1506 .probe = img_i2c_probe, 1507 .remove_new = img_i2c_remove, 1508 }; 1509 module_platform_driver(img_scb_i2c_driver); 1510 1511 MODULE_AUTHOR("James Hogan <jhogan@kernel.org>"); 1512 MODULE_DESCRIPTION("IMG host I2C driver"); 1513 MODULE_LICENSE("GPL v2"); 1514