1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * I2C bus driver for Amlogic Meson SoCs 4 * 5 * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com> 6 */ 7 8 #include <linux/bitfield.h> 9 #include <linux/clk.h> 10 #include <linux/completion.h> 11 #include <linux/i2c.h> 12 #include <linux/interrupt.h> 13 #include <linux/io.h> 14 #include <linux/iopoll.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/of_device.h> 19 #include <linux/platform_device.h> 20 #include <linux/types.h> 21 22 /* Meson I2C register map */ 23 #define REG_CTRL 0x00 24 #define REG_SLAVE_ADDR 0x04 25 #define REG_TOK_LIST0 0x08 26 #define REG_TOK_LIST1 0x0c 27 #define REG_TOK_WDATA0 0x10 28 #define REG_TOK_WDATA1 0x14 29 #define REG_TOK_RDATA0 0x18 30 #define REG_TOK_RDATA1 0x1c 31 32 /* Control register fields */ 33 #define REG_CTRL_START BIT(0) 34 #define REG_CTRL_ACK_IGNORE BIT(1) 35 #define REG_CTRL_STATUS BIT(2) 36 #define REG_CTRL_ERROR BIT(3) 37 #define REG_CTRL_CLKDIV_SHIFT 12 38 #define REG_CTRL_CLKDIV_MASK GENMASK(21, REG_CTRL_CLKDIV_SHIFT) 39 #define REG_CTRL_CLKDIVEXT_SHIFT 28 40 #define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, REG_CTRL_CLKDIVEXT_SHIFT) 41 42 #define REG_SLV_ADDR_MASK GENMASK(7, 0) 43 #define REG_SLV_SDA_FILTER_MASK GENMASK(10, 8) 44 #define REG_SLV_SCL_FILTER_MASK GENMASK(13, 11) 45 #define REG_SLV_SCL_LOW_SHIFT 16 46 #define REG_SLV_SCL_LOW_MASK GENMASK(27, REG_SLV_SCL_LOW_SHIFT) 47 #define REG_SLV_SCL_LOW_EN BIT(28) 48 49 #define I2C_TIMEOUT_MS 500 50 #define FILTER_DELAY 15 51 52 enum { 53 TOKEN_END = 0, 54 TOKEN_START, 55 TOKEN_SLAVE_ADDR_WRITE, 56 TOKEN_SLAVE_ADDR_READ, 57 TOKEN_DATA, 58 TOKEN_DATA_LAST, 59 TOKEN_STOP, 60 }; 61 62 enum { 63 STATE_IDLE, 64 STATE_READ, 65 STATE_WRITE, 66 }; 67 68 /** 69 * struct meson_i2c - Meson I2C device private data 70 * 71 * @adap: I2C adapter instance 72 * @dev: Pointer to device structure 73 * @regs: Base address of the device memory mapped registers 74 * @clk: Pointer to clock structure 75 * @msg: Pointer to the current I2C message 76 * @state: Current state in the driver state machine 77 * @last: Flag set for the last message in the transfer 78 * @count: Number of bytes to be sent/received in current transfer 79 * @pos: Current position in the send/receive buffer 80 * @error: Flag set when an error is received 81 * @lock: To avoid race conditions between irq handler and xfer code 82 * @done: Completion used to wait for transfer termination 83 * @tokens: Sequence of tokens to be written to the device 84 * @num_tokens: Number of tokens 85 * @data: Pointer to the controller's platform data 86 */ 87 struct meson_i2c { 88 struct i2c_adapter adap; 89 struct device *dev; 90 void __iomem *regs; 91 struct clk *clk; 92 93 struct i2c_msg *msg; 94 int state; 95 bool last; 96 int count; 97 int pos; 98 int error; 99 100 spinlock_t lock; 101 struct completion done; 102 u32 tokens[2]; 103 int num_tokens; 104 105 const struct meson_i2c_data *data; 106 }; 107 108 struct meson_i2c_data { 109 void (*set_clk_div)(struct meson_i2c *i2c, unsigned int freq); 110 }; 111 112 static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask, 113 u32 val) 114 { 115 u32 data; 116 117 data = readl(i2c->regs + reg); 118 data &= ~mask; 119 data |= val & mask; 120 writel(data, i2c->regs + reg); 121 } 122 123 static void meson_i2c_reset_tokens(struct meson_i2c *i2c) 124 { 125 i2c->tokens[0] = 0; 126 i2c->tokens[1] = 0; 127 i2c->num_tokens = 0; 128 } 129 130 static void meson_i2c_add_token(struct meson_i2c *i2c, int token) 131 { 132 if (i2c->num_tokens < 8) 133 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4); 134 else 135 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4); 136 137 i2c->num_tokens++; 138 } 139 140 static void meson_gxbb_axg_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq) 141 { 142 unsigned long clk_rate = clk_get_rate(i2c->clk); 143 unsigned int div_h, div_l; 144 145 /* According to I2C-BUS Spec 2.1, in FAST-MODE, the minimum LOW period is 1.3uS, and 146 * minimum HIGH is least 0.6us. 147 * For 400000 freq, the period is 2.5us. To keep within the specs, give 40% of period to 148 * HIGH and 60% to LOW. This means HIGH at 1.0us and LOW 1.5us. 149 * The same applies for Fast-mode plus, where LOW is 0.5us and HIGH is 0.26us. 150 * Duty = H/(H + L) = 2/5 151 */ 152 if (freq <= I2C_MAX_STANDARD_MODE_FREQ) { 153 div_h = DIV_ROUND_UP(clk_rate, freq); 154 div_l = DIV_ROUND_UP(div_h, 4); 155 div_h = DIV_ROUND_UP(div_h, 2) - FILTER_DELAY; 156 } else { 157 div_h = DIV_ROUND_UP(clk_rate * 2, freq * 5) - FILTER_DELAY; 158 div_l = DIV_ROUND_UP(clk_rate * 3, freq * 5 * 2); 159 } 160 161 /* clock divider has 12 bits */ 162 if (div_h > GENMASK(11, 0)) { 163 dev_err(i2c->dev, "requested bus frequency too low\n"); 164 div_h = GENMASK(11, 0); 165 } 166 if (div_l > GENMASK(11, 0)) { 167 dev_err(i2c->dev, "requested bus frequency too low\n"); 168 div_l = GENMASK(11, 0); 169 } 170 171 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK, 172 FIELD_PREP(REG_CTRL_CLKDIV_MASK, div_h & GENMASK(9, 0))); 173 174 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK, 175 FIELD_PREP(REG_CTRL_CLKDIVEXT_MASK, div_h >> 10)); 176 177 /* set SCL low delay */ 178 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_MASK, 179 FIELD_PREP(REG_SLV_SCL_LOW_MASK, div_l)); 180 181 /* Enable HIGH/LOW mode */ 182 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, REG_SLV_SCL_LOW_EN); 183 184 dev_dbg(i2c->dev, "%s: clk %lu, freq %u, divh %u, divl %u\n", __func__, 185 clk_rate, freq, div_h, div_l); 186 } 187 188 static void meson6_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq) 189 { 190 unsigned long clk_rate = clk_get_rate(i2c->clk); 191 unsigned int div; 192 193 div = DIV_ROUND_UP(clk_rate, freq); 194 div -= FILTER_DELAY; 195 div = DIV_ROUND_UP(div, 4); 196 197 /* clock divider has 12 bits */ 198 if (div > GENMASK(11, 0)) { 199 dev_err(i2c->dev, "requested bus frequency too low\n"); 200 div = GENMASK(11, 0); 201 } 202 203 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK, 204 FIELD_PREP(REG_CTRL_CLKDIV_MASK, div & GENMASK(9, 0))); 205 206 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK, 207 FIELD_PREP(REG_CTRL_CLKDIVEXT_MASK, div >> 10)); 208 209 /* Disable HIGH/LOW mode */ 210 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, 0); 211 212 dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__, 213 clk_rate, freq, div); 214 } 215 216 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len) 217 { 218 u32 rdata0, rdata1; 219 int i; 220 221 rdata0 = readl(i2c->regs + REG_TOK_RDATA0); 222 rdata1 = readl(i2c->regs + REG_TOK_RDATA1); 223 224 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__, 225 rdata0, rdata1, len); 226 227 for (i = 0; i < min(4, len); i++) 228 *buf++ = (rdata0 >> i * 8) & 0xff; 229 230 for (i = 4; i < min(8, len); i++) 231 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff; 232 } 233 234 static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len) 235 { 236 u32 wdata0 = 0, wdata1 = 0; 237 int i; 238 239 for (i = 0; i < min(4, len); i++) 240 wdata0 |= *buf++ << (i * 8); 241 242 for (i = 4; i < min(8, len); i++) 243 wdata1 |= *buf++ << ((i - 4) * 8); 244 245 writel(wdata0, i2c->regs + REG_TOK_WDATA0); 246 writel(wdata1, i2c->regs + REG_TOK_WDATA1); 247 248 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__, 249 wdata0, wdata1, len); 250 } 251 252 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c) 253 { 254 bool write = !(i2c->msg->flags & I2C_M_RD); 255 int i; 256 257 i2c->count = min(i2c->msg->len - i2c->pos, 8); 258 259 for (i = 0; i < i2c->count - 1; i++) 260 meson_i2c_add_token(i2c, TOKEN_DATA); 261 262 if (i2c->count) { 263 if (write || i2c->pos + i2c->count < i2c->msg->len) 264 meson_i2c_add_token(i2c, TOKEN_DATA); 265 else 266 meson_i2c_add_token(i2c, TOKEN_DATA_LAST); 267 } 268 269 if (write) 270 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count); 271 272 if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len) 273 meson_i2c_add_token(i2c, TOKEN_STOP); 274 275 writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0); 276 writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1); 277 } 278 279 static void meson_i2c_transfer_complete(struct meson_i2c *i2c, u32 ctrl) 280 { 281 if (ctrl & REG_CTRL_ERROR) { 282 /* 283 * The bit is set when the IGNORE_NAK bit is cleared 284 * and the device didn't respond. In this case, the 285 * I2C controller automatically generates a STOP 286 * condition. 287 */ 288 dev_dbg(i2c->dev, "error bit set\n"); 289 i2c->error = -ENXIO; 290 i2c->state = STATE_IDLE; 291 } else { 292 if (i2c->state == STATE_READ && i2c->count) 293 meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos, 294 i2c->count); 295 296 i2c->pos += i2c->count; 297 298 if (i2c->pos >= i2c->msg->len) 299 i2c->state = STATE_IDLE; 300 } 301 } 302 303 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id) 304 { 305 struct meson_i2c *i2c = dev_id; 306 unsigned int ctrl; 307 308 spin_lock(&i2c->lock); 309 310 meson_i2c_reset_tokens(i2c); 311 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0); 312 ctrl = readl(i2c->regs + REG_CTRL); 313 314 dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n", 315 i2c->state, i2c->pos, i2c->count, ctrl); 316 317 if (i2c->state == STATE_IDLE) { 318 spin_unlock(&i2c->lock); 319 return IRQ_NONE; 320 } 321 322 meson_i2c_transfer_complete(i2c, ctrl); 323 324 if (i2c->state == STATE_IDLE) { 325 complete(&i2c->done); 326 goto out; 327 } 328 329 /* Restart the processing */ 330 meson_i2c_prepare_xfer(i2c); 331 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START); 332 out: 333 spin_unlock(&i2c->lock); 334 335 return IRQ_HANDLED; 336 } 337 338 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg) 339 { 340 int token; 341 342 token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ : 343 TOKEN_SLAVE_ADDR_WRITE; 344 345 346 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_ADDR_MASK, 347 FIELD_PREP(REG_SLV_ADDR_MASK, msg->addr << 1)); 348 349 meson_i2c_add_token(i2c, TOKEN_START); 350 meson_i2c_add_token(i2c, token); 351 } 352 353 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg, 354 int last, bool atomic) 355 { 356 unsigned long time_left, flags; 357 int ret = 0; 358 u32 ctrl; 359 360 i2c->msg = msg; 361 i2c->last = last; 362 i2c->pos = 0; 363 i2c->count = 0; 364 i2c->error = 0; 365 366 meson_i2c_reset_tokens(i2c); 367 368 flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0; 369 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags); 370 371 if (!(msg->flags & I2C_M_NOSTART)) 372 meson_i2c_do_start(i2c, msg); 373 374 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE; 375 meson_i2c_prepare_xfer(i2c); 376 377 if (!atomic) 378 reinit_completion(&i2c->done); 379 380 /* Start the transfer */ 381 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START); 382 383 if (atomic) { 384 ret = readl_poll_timeout_atomic(i2c->regs + REG_CTRL, ctrl, 385 !(ctrl & REG_CTRL_STATUS), 386 10, I2C_TIMEOUT_MS * 1000); 387 } else { 388 time_left = msecs_to_jiffies(I2C_TIMEOUT_MS); 389 time_left = wait_for_completion_timeout(&i2c->done, time_left); 390 391 if (!time_left) 392 ret = -ETIMEDOUT; 393 } 394 395 /* 396 * Protect access to i2c struct and registers from interrupt 397 * handlers triggered by a transfer terminated after the 398 * timeout period 399 */ 400 spin_lock_irqsave(&i2c->lock, flags); 401 402 if (atomic && !ret) 403 meson_i2c_transfer_complete(i2c, ctrl); 404 405 /* Abort any active operation */ 406 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0); 407 408 if (ret) 409 i2c->state = STATE_IDLE; 410 411 if (i2c->error) 412 ret = i2c->error; 413 414 spin_unlock_irqrestore(&i2c->lock, flags); 415 416 return ret; 417 } 418 419 static int meson_i2c_xfer_messages(struct i2c_adapter *adap, 420 struct i2c_msg *msgs, int num, bool atomic) 421 { 422 struct meson_i2c *i2c = adap->algo_data; 423 int i, ret = 0; 424 425 for (i = 0; i < num; i++) { 426 ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1, atomic); 427 if (ret) 428 break; 429 } 430 431 return ret ?: i; 432 } 433 434 static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, 435 int num) 436 { 437 return meson_i2c_xfer_messages(adap, msgs, num, false); 438 } 439 440 static int meson_i2c_xfer_atomic(struct i2c_adapter *adap, 441 struct i2c_msg *msgs, int num) 442 { 443 return meson_i2c_xfer_messages(adap, msgs, num, true); 444 } 445 446 static u32 meson_i2c_func(struct i2c_adapter *adap) 447 { 448 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 449 } 450 451 static const struct i2c_algorithm meson_i2c_algorithm = { 452 .master_xfer = meson_i2c_xfer, 453 .master_xfer_atomic = meson_i2c_xfer_atomic, 454 .functionality = meson_i2c_func, 455 }; 456 457 static int meson_i2c_probe(struct platform_device *pdev) 458 { 459 struct device_node *np = pdev->dev.of_node; 460 struct meson_i2c *i2c; 461 struct i2c_timings timings; 462 int irq, ret = 0; 463 464 i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL); 465 if (!i2c) 466 return -ENOMEM; 467 468 i2c_parse_fw_timings(&pdev->dev, &timings, true); 469 470 i2c->dev = &pdev->dev; 471 platform_set_drvdata(pdev, i2c); 472 473 spin_lock_init(&i2c->lock); 474 init_completion(&i2c->done); 475 476 i2c->data = (const struct meson_i2c_data *) 477 of_device_get_match_data(&pdev->dev); 478 479 i2c->clk = devm_clk_get(&pdev->dev, NULL); 480 if (IS_ERR(i2c->clk)) { 481 dev_err(&pdev->dev, "can't get device clock\n"); 482 return PTR_ERR(i2c->clk); 483 } 484 485 i2c->regs = devm_platform_ioremap_resource(pdev, 0); 486 if (IS_ERR(i2c->regs)) 487 return PTR_ERR(i2c->regs); 488 489 irq = platform_get_irq(pdev, 0); 490 if (irq < 0) 491 return irq; 492 493 ret = devm_request_irq(&pdev->dev, irq, meson_i2c_irq, 0, NULL, i2c); 494 if (ret < 0) { 495 dev_err(&pdev->dev, "can't request IRQ\n"); 496 return ret; 497 } 498 499 ret = clk_prepare_enable(i2c->clk); 500 if (ret < 0) { 501 dev_err(&pdev->dev, "can't prepare clock\n"); 502 return ret; 503 } 504 505 strlcpy(i2c->adap.name, "Meson I2C adapter", 506 sizeof(i2c->adap.name)); 507 i2c->adap.owner = THIS_MODULE; 508 i2c->adap.algo = &meson_i2c_algorithm; 509 i2c->adap.dev.parent = &pdev->dev; 510 i2c->adap.dev.of_node = np; 511 i2c->adap.algo_data = i2c; 512 513 /* 514 * A transfer is triggered when START bit changes from 0 to 1. 515 * Ensure that the bit is set to 0 after probe 516 */ 517 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0); 518 519 /* Disable filtering */ 520 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, 521 REG_SLV_SDA_FILTER_MASK | REG_SLV_SCL_FILTER_MASK, 0); 522 523 if (!i2c->data->set_clk_div) { 524 clk_disable_unprepare(i2c->clk); 525 return -EINVAL; 526 } 527 i2c->data->set_clk_div(i2c, timings.bus_freq_hz); 528 529 ret = i2c_add_adapter(&i2c->adap); 530 if (ret < 0) { 531 clk_disable_unprepare(i2c->clk); 532 return ret; 533 } 534 535 return 0; 536 } 537 538 static int meson_i2c_remove(struct platform_device *pdev) 539 { 540 struct meson_i2c *i2c = platform_get_drvdata(pdev); 541 542 i2c_del_adapter(&i2c->adap); 543 clk_disable_unprepare(i2c->clk); 544 545 return 0; 546 } 547 548 static const struct meson_i2c_data i2c_meson6_data = { 549 .set_clk_div = meson6_i2c_set_clk_div, 550 }; 551 552 static const struct meson_i2c_data i2c_gxbb_data = { 553 .set_clk_div = meson_gxbb_axg_i2c_set_clk_div, 554 }; 555 556 static const struct meson_i2c_data i2c_axg_data = { 557 .set_clk_div = meson_gxbb_axg_i2c_set_clk_div, 558 }; 559 560 static const struct of_device_id meson_i2c_match[] = { 561 { .compatible = "amlogic,meson6-i2c", .data = &i2c_meson6_data }, 562 { .compatible = "amlogic,meson-gxbb-i2c", .data = &i2c_gxbb_data }, 563 { .compatible = "amlogic,meson-axg-i2c", .data = &i2c_axg_data }, 564 {}, 565 }; 566 567 MODULE_DEVICE_TABLE(of, meson_i2c_match); 568 569 static struct platform_driver meson_i2c_driver = { 570 .probe = meson_i2c_probe, 571 .remove = meson_i2c_remove, 572 .driver = { 573 .name = "meson-i2c", 574 .of_match_table = meson_i2c_match, 575 }, 576 }; 577 578 module_platform_driver(meson_i2c_driver); 579 580 MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver"); 581 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>"); 582 MODULE_LICENSE("GPL v2"); 583