1 /* 2 * This driver implements I2C master functionality using the LSI API2C 3 * controller. 4 * 5 * NOTE: The controller has a limitation in that it can only do transfers of 6 * maximum 255 bytes at a time. If a larger transfer is attempted, error code 7 * (-EINVAL) is returned. 8 * 9 * This software is licensed under the terms of the GNU General Public 10 * License version 2, as published by the Free Software Foundation, and 11 * may be copied, distributed, and modified under those terms. 12 */ 13 #include <linux/clk.h> 14 #include <linux/clkdev.h> 15 #include <linux/err.h> 16 #include <linux/i2c.h> 17 #include <linux/init.h> 18 #include <linux/interrupt.h> 19 #include <linux/module.h> 20 #include <linux/io.h> 21 #include <linux/kernel.h> 22 #include <linux/platform_device.h> 23 24 #define SCL_WAIT_TIMEOUT_NS 25000000 25 #define I2C_XFER_TIMEOUT (msecs_to_jiffies(250)) 26 #define I2C_STOP_TIMEOUT (msecs_to_jiffies(100)) 27 #define FIFO_SIZE 8 28 29 #define GLOBAL_CONTROL 0x00 30 #define GLOBAL_MST_EN BIT(0) 31 #define GLOBAL_SLV_EN BIT(1) 32 #define GLOBAL_IBML_EN BIT(2) 33 #define INTERRUPT_STATUS 0x04 34 #define INTERRUPT_ENABLE 0x08 35 #define INT_SLV BIT(1) 36 #define INT_MST BIT(0) 37 #define WAIT_TIMER_CONTROL 0x0c 38 #define WT_EN BIT(15) 39 #define WT_VALUE(_x) ((_x) & 0x7fff) 40 #define IBML_TIMEOUT 0x10 41 #define IBML_LOW_MEXT 0x14 42 #define IBML_LOW_SEXT 0x18 43 #define TIMER_CLOCK_DIV 0x1c 44 #define I2C_BUS_MONITOR 0x20 45 #define BM_SDAC BIT(3) 46 #define BM_SCLC BIT(2) 47 #define BM_SDAS BIT(1) 48 #define BM_SCLS BIT(0) 49 #define SOFT_RESET 0x24 50 #define MST_COMMAND 0x28 51 #define CMD_BUSY (1<<3) 52 #define CMD_MANUAL (0x00 | CMD_BUSY) 53 #define CMD_AUTO (0x01 | CMD_BUSY) 54 #define MST_RX_XFER 0x2c 55 #define MST_TX_XFER 0x30 56 #define MST_ADDR_1 0x34 57 #define MST_ADDR_2 0x38 58 #define MST_DATA 0x3c 59 #define MST_TX_FIFO 0x40 60 #define MST_RX_FIFO 0x44 61 #define MST_INT_ENABLE 0x48 62 #define MST_INT_STATUS 0x4c 63 #define MST_STATUS_RFL (1 << 13) /* RX FIFO serivce */ 64 #define MST_STATUS_TFL (1 << 12) /* TX FIFO service */ 65 #define MST_STATUS_SNS (1 << 11) /* Manual mode done */ 66 #define MST_STATUS_SS (1 << 10) /* Automatic mode done */ 67 #define MST_STATUS_SCC (1 << 9) /* Stop complete */ 68 #define MST_STATUS_IP (1 << 8) /* Invalid parameter */ 69 #define MST_STATUS_TSS (1 << 7) /* Timeout */ 70 #define MST_STATUS_AL (1 << 6) /* Arbitration lost */ 71 #define MST_STATUS_ND (1 << 5) /* NAK on data phase */ 72 #define MST_STATUS_NA (1 << 4) /* NAK on address phase */ 73 #define MST_STATUS_NAK (MST_STATUS_NA | \ 74 MST_STATUS_ND) 75 #define MST_STATUS_ERR (MST_STATUS_NAK | \ 76 MST_STATUS_AL | \ 77 MST_STATUS_IP | \ 78 MST_STATUS_TSS) 79 #define MST_TX_BYTES_XFRD 0x50 80 #define MST_RX_BYTES_XFRD 0x54 81 #define SCL_HIGH_PERIOD 0x80 82 #define SCL_LOW_PERIOD 0x84 83 #define SPIKE_FLTR_LEN 0x88 84 #define SDA_SETUP_TIME 0x8c 85 #define SDA_HOLD_TIME 0x90 86 87 /** 88 * axxia_i2c_dev - I2C device context 89 * @base: pointer to register struct 90 * @msg: pointer to current message 91 * @msg_xfrd: number of bytes transferred in msg 92 * @msg_err: error code for completed message 93 * @msg_complete: xfer completion object 94 * @dev: device reference 95 * @adapter: core i2c abstraction 96 * @i2c_clk: clock reference for i2c input clock 97 * @bus_clk_rate: current i2c bus clock rate 98 */ 99 struct axxia_i2c_dev { 100 void __iomem *base; 101 struct i2c_msg *msg; 102 size_t msg_xfrd; 103 int msg_err; 104 struct completion msg_complete; 105 struct device *dev; 106 struct i2c_adapter adapter; 107 struct clk *i2c_clk; 108 u32 bus_clk_rate; 109 }; 110 111 static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask) 112 { 113 u32 int_en; 114 115 int_en = readl(idev->base + MST_INT_ENABLE); 116 writel(int_en & ~mask, idev->base + MST_INT_ENABLE); 117 } 118 119 static void i2c_int_enable(struct axxia_i2c_dev *idev, u32 mask) 120 { 121 u32 int_en; 122 123 int_en = readl(idev->base + MST_INT_ENABLE); 124 writel(int_en | mask, idev->base + MST_INT_ENABLE); 125 } 126 127 /** 128 * ns_to_clk - Convert time (ns) to clock cycles for the given clock frequency. 129 */ 130 static u32 ns_to_clk(u64 ns, u32 clk_mhz) 131 { 132 return div_u64(ns * clk_mhz, 1000); 133 } 134 135 static int axxia_i2c_init(struct axxia_i2c_dev *idev) 136 { 137 u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate; 138 u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000; 139 u32 t_setup; 140 u32 t_high, t_low; 141 u32 tmo_clk; 142 u32 prescale; 143 unsigned long timeout; 144 145 dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n", 146 idev->bus_clk_rate, clk_mhz, divisor); 147 148 /* Reset controller */ 149 writel(0x01, idev->base + SOFT_RESET); 150 timeout = jiffies + msecs_to_jiffies(100); 151 while (readl(idev->base + SOFT_RESET) & 1) { 152 if (time_after(jiffies, timeout)) { 153 dev_warn(idev->dev, "Soft reset failed\n"); 154 break; 155 } 156 } 157 158 /* Enable Master Mode */ 159 writel(0x1, idev->base + GLOBAL_CONTROL); 160 161 if (idev->bus_clk_rate <= 100000) { 162 /* Standard mode SCL 50/50, tSU:DAT = 250 ns */ 163 t_high = divisor * 1 / 2; 164 t_low = divisor * 1 / 2; 165 t_setup = ns_to_clk(250, clk_mhz); 166 } else { 167 /* Fast mode SCL 33/66, tSU:DAT = 100 ns */ 168 t_high = divisor * 1 / 3; 169 t_low = divisor * 2 / 3; 170 t_setup = ns_to_clk(100, clk_mhz); 171 } 172 173 /* SCL High Time */ 174 writel(t_high, idev->base + SCL_HIGH_PERIOD); 175 /* SCL Low Time */ 176 writel(t_low, idev->base + SCL_LOW_PERIOD); 177 /* SDA Setup Time */ 178 writel(t_setup, idev->base + SDA_SETUP_TIME); 179 /* SDA Hold Time, 300ns */ 180 writel(ns_to_clk(300, clk_mhz), idev->base + SDA_HOLD_TIME); 181 /* Filter <50ns spikes */ 182 writel(ns_to_clk(50, clk_mhz), idev->base + SPIKE_FLTR_LEN); 183 184 /* Configure Time-Out Registers */ 185 tmo_clk = ns_to_clk(SCL_WAIT_TIMEOUT_NS, clk_mhz); 186 187 /* Find prescaler value that makes tmo_clk fit in 15-bits counter. */ 188 for (prescale = 0; prescale < 15; ++prescale) { 189 if (tmo_clk <= 0x7fff) 190 break; 191 tmo_clk >>= 1; 192 } 193 if (tmo_clk > 0x7fff) 194 tmo_clk = 0x7fff; 195 196 /* Prescale divider (log2) */ 197 writel(prescale, idev->base + TIMER_CLOCK_DIV); 198 /* Timeout in divided clocks */ 199 writel(WT_EN | WT_VALUE(tmo_clk), idev->base + WAIT_TIMER_CONTROL); 200 201 /* Mask all master interrupt bits */ 202 i2c_int_disable(idev, ~0); 203 204 /* Interrupt enable */ 205 writel(0x01, idev->base + INTERRUPT_ENABLE); 206 207 return 0; 208 } 209 210 static int i2c_m_rd(const struct i2c_msg *msg) 211 { 212 return (msg->flags & I2C_M_RD) != 0; 213 } 214 215 static int i2c_m_ten(const struct i2c_msg *msg) 216 { 217 return (msg->flags & I2C_M_TEN) != 0; 218 } 219 220 static int i2c_m_recv_len(const struct i2c_msg *msg) 221 { 222 return (msg->flags & I2C_M_RECV_LEN) != 0; 223 } 224 225 /** 226 * axxia_i2c_empty_rx_fifo - Fetch data from RX FIFO and update SMBus block 227 * transfer length if this is the first byte of such a transfer. 228 */ 229 static int axxia_i2c_empty_rx_fifo(struct axxia_i2c_dev *idev) 230 { 231 struct i2c_msg *msg = idev->msg; 232 size_t rx_fifo_avail = readl(idev->base + MST_RX_FIFO); 233 int bytes_to_transfer = min(rx_fifo_avail, msg->len - idev->msg_xfrd); 234 235 while (bytes_to_transfer-- > 0) { 236 int c = readl(idev->base + MST_DATA); 237 238 if (idev->msg_xfrd == 0 && i2c_m_recv_len(msg)) { 239 /* 240 * Check length byte for SMBus block read 241 */ 242 if (c <= 0 || c > I2C_SMBUS_BLOCK_MAX) { 243 idev->msg_err = -EPROTO; 244 i2c_int_disable(idev, ~0); 245 complete(&idev->msg_complete); 246 break; 247 } 248 msg->len = 1 + c; 249 writel(msg->len, idev->base + MST_RX_XFER); 250 } 251 msg->buf[idev->msg_xfrd++] = c; 252 } 253 254 return 0; 255 } 256 257 /** 258 * axxia_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer. 259 * @return: Number of bytes left to transfer. 260 */ 261 static int axxia_i2c_fill_tx_fifo(struct axxia_i2c_dev *idev) 262 { 263 struct i2c_msg *msg = idev->msg; 264 size_t tx_fifo_avail = FIFO_SIZE - readl(idev->base + MST_TX_FIFO); 265 int bytes_to_transfer = min(tx_fifo_avail, msg->len - idev->msg_xfrd); 266 int ret = msg->len - idev->msg_xfrd - bytes_to_transfer; 267 268 while (bytes_to_transfer-- > 0) 269 writel(msg->buf[idev->msg_xfrd++], idev->base + MST_DATA); 270 271 return ret; 272 } 273 274 static irqreturn_t axxia_i2c_isr(int irq, void *_dev) 275 { 276 struct axxia_i2c_dev *idev = _dev; 277 u32 status; 278 279 if (!(readl(idev->base + INTERRUPT_STATUS) & INT_MST)) 280 return IRQ_NONE; 281 282 /* Read interrupt status bits */ 283 status = readl(idev->base + MST_INT_STATUS); 284 285 if (!idev->msg) { 286 dev_warn(idev->dev, "unexpected interrupt\n"); 287 goto out; 288 } 289 290 /* RX FIFO needs service? */ 291 if (i2c_m_rd(idev->msg) && (status & MST_STATUS_RFL)) 292 axxia_i2c_empty_rx_fifo(idev); 293 294 /* TX FIFO needs service? */ 295 if (!i2c_m_rd(idev->msg) && (status & MST_STATUS_TFL)) { 296 if (axxia_i2c_fill_tx_fifo(idev) == 0) 297 i2c_int_disable(idev, MST_STATUS_TFL); 298 } 299 300 if (status & MST_STATUS_SCC) { 301 /* Stop completed */ 302 i2c_int_disable(idev, ~0); 303 complete(&idev->msg_complete); 304 } else if (status & MST_STATUS_SNS) { 305 /* Transfer done */ 306 i2c_int_disable(idev, ~0); 307 if (i2c_m_rd(idev->msg) && idev->msg_xfrd < idev->msg->len) 308 axxia_i2c_empty_rx_fifo(idev); 309 complete(&idev->msg_complete); 310 } else if (unlikely(status & MST_STATUS_ERR)) { 311 /* Transfer error */ 312 i2c_int_disable(idev, ~0); 313 if (status & MST_STATUS_AL) 314 idev->msg_err = -EAGAIN; 315 else if (status & MST_STATUS_NAK) 316 idev->msg_err = -ENXIO; 317 else 318 idev->msg_err = -EIO; 319 dev_dbg(idev->dev, "error %#x, addr=%#x rx=%u/%u tx=%u/%u\n", 320 status, 321 idev->msg->addr, 322 readl(idev->base + MST_RX_BYTES_XFRD), 323 readl(idev->base + MST_RX_XFER), 324 readl(idev->base + MST_TX_BYTES_XFRD), 325 readl(idev->base + MST_TX_XFER)); 326 complete(&idev->msg_complete); 327 } 328 329 out: 330 /* Clear interrupt */ 331 writel(INT_MST, idev->base + INTERRUPT_STATUS); 332 333 return IRQ_HANDLED; 334 } 335 336 static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg) 337 { 338 u32 int_mask = MST_STATUS_ERR | MST_STATUS_SNS; 339 u32 rx_xfer, tx_xfer; 340 u32 addr_1, addr_2; 341 unsigned long time_left; 342 343 idev->msg = msg; 344 idev->msg_xfrd = 0; 345 idev->msg_err = 0; 346 reinit_completion(&idev->msg_complete); 347 348 if (i2c_m_ten(msg)) { 349 /* 10-bit address 350 * addr_1: 5'b11110 | addr[9:8] | (R/nW) 351 * addr_2: addr[7:0] 352 */ 353 addr_1 = 0xF0 | ((msg->addr >> 7) & 0x06); 354 addr_2 = msg->addr & 0xFF; 355 } else { 356 /* 7-bit address 357 * addr_1: addr[6:0] | (R/nW) 358 * addr_2: dont care 359 */ 360 addr_1 = (msg->addr << 1) & 0xFF; 361 addr_2 = 0; 362 } 363 364 if (i2c_m_rd(msg)) { 365 /* I2C read transfer */ 366 rx_xfer = i2c_m_recv_len(msg) ? I2C_SMBUS_BLOCK_MAX : msg->len; 367 tx_xfer = 0; 368 addr_1 |= 1; /* Set the R/nW bit of the address */ 369 } else { 370 /* I2C write transfer */ 371 rx_xfer = 0; 372 tx_xfer = msg->len; 373 } 374 375 writel(rx_xfer, idev->base + MST_RX_XFER); 376 writel(tx_xfer, idev->base + MST_TX_XFER); 377 writel(addr_1, idev->base + MST_ADDR_1); 378 writel(addr_2, idev->base + MST_ADDR_2); 379 380 if (i2c_m_rd(msg)) 381 int_mask |= MST_STATUS_RFL; 382 else if (axxia_i2c_fill_tx_fifo(idev) != 0) 383 int_mask |= MST_STATUS_TFL; 384 385 /* Start manual mode */ 386 writel(CMD_MANUAL, idev->base + MST_COMMAND); 387 388 i2c_int_enable(idev, int_mask); 389 390 time_left = wait_for_completion_timeout(&idev->msg_complete, 391 I2C_XFER_TIMEOUT); 392 393 i2c_int_disable(idev, int_mask); 394 395 if (readl(idev->base + MST_COMMAND) & CMD_BUSY) 396 dev_warn(idev->dev, "busy after xfer\n"); 397 398 if (time_left == 0) 399 idev->msg_err = -ETIMEDOUT; 400 401 if (idev->msg_err == -ETIMEDOUT) 402 i2c_recover_bus(&idev->adapter); 403 404 if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO) 405 axxia_i2c_init(idev); 406 407 return idev->msg_err; 408 } 409 410 static int axxia_i2c_stop(struct axxia_i2c_dev *idev) 411 { 412 u32 int_mask = MST_STATUS_ERR | MST_STATUS_SCC; 413 unsigned long time_left; 414 415 reinit_completion(&idev->msg_complete); 416 417 /* Issue stop */ 418 writel(0xb, idev->base + MST_COMMAND); 419 i2c_int_enable(idev, int_mask); 420 time_left = wait_for_completion_timeout(&idev->msg_complete, 421 I2C_STOP_TIMEOUT); 422 i2c_int_disable(idev, int_mask); 423 if (time_left == 0) 424 return -ETIMEDOUT; 425 426 if (readl(idev->base + MST_COMMAND) & CMD_BUSY) 427 dev_warn(idev->dev, "busy after stop\n"); 428 429 return 0; 430 } 431 432 static int 433 axxia_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) 434 { 435 struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); 436 int i; 437 int ret = 0; 438 439 for (i = 0; ret == 0 && i < num; ++i) 440 ret = axxia_i2c_xfer_msg(idev, &msgs[i]); 441 442 axxia_i2c_stop(idev); 443 444 return ret ? : i; 445 } 446 447 static int axxia_i2c_get_scl(struct i2c_adapter *adap) 448 { 449 struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); 450 451 return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SCLS); 452 } 453 454 static void axxia_i2c_set_scl(struct i2c_adapter *adap, int val) 455 { 456 struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); 457 u32 tmp; 458 459 /* Preserve SDA Control */ 460 tmp = readl(idev->base + I2C_BUS_MONITOR) & BM_SDAC; 461 if (!val) 462 tmp |= BM_SCLC; 463 writel(tmp, idev->base + I2C_BUS_MONITOR); 464 } 465 466 static int axxia_i2c_get_sda(struct i2c_adapter *adap) 467 { 468 struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); 469 470 return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SDAS); 471 } 472 473 static struct i2c_bus_recovery_info axxia_i2c_recovery_info = { 474 .recover_bus = i2c_generic_scl_recovery, 475 .get_scl = axxia_i2c_get_scl, 476 .set_scl = axxia_i2c_set_scl, 477 .get_sda = axxia_i2c_get_sda, 478 }; 479 480 static u32 axxia_i2c_func(struct i2c_adapter *adap) 481 { 482 u32 caps = (I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | 483 I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA); 484 return caps; 485 } 486 487 static const struct i2c_algorithm axxia_i2c_algo = { 488 .master_xfer = axxia_i2c_xfer, 489 .functionality = axxia_i2c_func, 490 }; 491 492 static struct i2c_adapter_quirks axxia_i2c_quirks = { 493 .max_read_len = 255, 494 .max_write_len = 255, 495 }; 496 497 static int axxia_i2c_probe(struct platform_device *pdev) 498 { 499 struct device_node *np = pdev->dev.of_node; 500 struct axxia_i2c_dev *idev = NULL; 501 struct resource *res; 502 void __iomem *base; 503 int irq; 504 int ret = 0; 505 506 idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL); 507 if (!idev) 508 return -ENOMEM; 509 510 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 511 base = devm_ioremap_resource(&pdev->dev, res); 512 if (IS_ERR(base)) 513 return PTR_ERR(base); 514 515 irq = platform_get_irq(pdev, 0); 516 if (irq < 0) { 517 dev_err(&pdev->dev, "missing interrupt resource\n"); 518 return irq; 519 } 520 521 idev->i2c_clk = devm_clk_get(&pdev->dev, "i2c"); 522 if (IS_ERR(idev->i2c_clk)) { 523 dev_err(&pdev->dev, "missing clock\n"); 524 return PTR_ERR(idev->i2c_clk); 525 } 526 527 idev->base = base; 528 idev->dev = &pdev->dev; 529 init_completion(&idev->msg_complete); 530 531 of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate); 532 if (idev->bus_clk_rate == 0) 533 idev->bus_clk_rate = 100000; /* default clock rate */ 534 535 ret = axxia_i2c_init(idev); 536 if (ret) { 537 dev_err(&pdev->dev, "failed to initialize\n"); 538 return ret; 539 } 540 541 ret = devm_request_irq(&pdev->dev, irq, axxia_i2c_isr, 0, 542 pdev->name, idev); 543 if (ret) { 544 dev_err(&pdev->dev, "failed to claim IRQ%d\n", irq); 545 return ret; 546 } 547 548 clk_prepare_enable(idev->i2c_clk); 549 550 i2c_set_adapdata(&idev->adapter, idev); 551 strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name)); 552 idev->adapter.owner = THIS_MODULE; 553 idev->adapter.algo = &axxia_i2c_algo; 554 idev->adapter.bus_recovery_info = &axxia_i2c_recovery_info; 555 idev->adapter.quirks = &axxia_i2c_quirks; 556 idev->adapter.dev.parent = &pdev->dev; 557 idev->adapter.dev.of_node = pdev->dev.of_node; 558 559 platform_set_drvdata(pdev, idev); 560 561 ret = i2c_add_adapter(&idev->adapter); 562 if (ret) { 563 dev_err(&pdev->dev, "failed to add adapter\n"); 564 return ret; 565 } 566 567 return 0; 568 } 569 570 static int axxia_i2c_remove(struct platform_device *pdev) 571 { 572 struct axxia_i2c_dev *idev = platform_get_drvdata(pdev); 573 574 clk_disable_unprepare(idev->i2c_clk); 575 i2c_del_adapter(&idev->adapter); 576 577 return 0; 578 } 579 580 /* Match table for of_platform binding */ 581 static const struct of_device_id axxia_i2c_of_match[] = { 582 { .compatible = "lsi,api2c", }, 583 {}, 584 }; 585 586 MODULE_DEVICE_TABLE(of, axxia_i2c_of_match); 587 588 static struct platform_driver axxia_i2c_driver = { 589 .probe = axxia_i2c_probe, 590 .remove = axxia_i2c_remove, 591 .driver = { 592 .name = "axxia-i2c", 593 .of_match_table = axxia_i2c_of_match, 594 }, 595 }; 596 597 module_platform_driver(axxia_i2c_driver); 598 599 MODULE_DESCRIPTION("Axxia I2C Bus driver"); 600 MODULE_AUTHOR("Anders Berg <anders.berg@lsi.com>"); 601 MODULE_LICENSE("GPL v2"); 602