1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2011 NXP Semiconductors 4 * 5 * Code portions referenced from the i2x-pxa and i2c-pnx drivers 6 * 7 * Make SMBus byte and word transactions work on LPC178x/7x 8 * Copyright (c) 2012 9 * Alexander Potashev, Emcraft Systems, aspotashev@emcraft.com 10 * Anton Protopopov, Emcraft Systems, antonp@emcraft.com 11 * 12 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com> 13 */ 14 15 #include <linux/clk.h> 16 #include <linux/errno.h> 17 #include <linux/i2c.h> 18 #include <linux/interrupt.h> 19 #include <linux/io.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/of.h> 23 #include <linux/of_device.h> 24 #include <linux/platform_device.h> 25 #include <linux/sched.h> 26 #include <linux/time.h> 27 28 /* LPC24xx register offsets and bits */ 29 #define LPC24XX_I2CONSET 0x00 30 #define LPC24XX_I2STAT 0x04 31 #define LPC24XX_I2DAT 0x08 32 #define LPC24XX_I2ADDR 0x0c 33 #define LPC24XX_I2SCLH 0x10 34 #define LPC24XX_I2SCLL 0x14 35 #define LPC24XX_I2CONCLR 0x18 36 37 #define LPC24XX_AA BIT(2) 38 #define LPC24XX_SI BIT(3) 39 #define LPC24XX_STO BIT(4) 40 #define LPC24XX_STA BIT(5) 41 #define LPC24XX_I2EN BIT(6) 42 43 #define LPC24XX_STO_AA (LPC24XX_STO | LPC24XX_AA) 44 #define LPC24XX_CLEAR_ALL (LPC24XX_AA | LPC24XX_SI | LPC24XX_STO | \ 45 LPC24XX_STA | LPC24XX_I2EN) 46 47 /* I2C SCL clock has different duty cycle depending on mode */ 48 #define I2C_STD_MODE_DUTY 46 49 #define I2C_FAST_MODE_DUTY 36 50 #define I2C_FAST_MODE_PLUS_DUTY 38 51 52 /* 53 * 26 possible I2C status codes, but codes applicable only 54 * to master are listed here and used in this driver 55 */ 56 enum { 57 M_BUS_ERROR = 0x00, 58 M_START = 0x08, 59 M_REPSTART = 0x10, 60 MX_ADDR_W_ACK = 0x18, 61 MX_ADDR_W_NACK = 0x20, 62 MX_DATA_W_ACK = 0x28, 63 MX_DATA_W_NACK = 0x30, 64 M_DATA_ARB_LOST = 0x38, 65 MR_ADDR_R_ACK = 0x40, 66 MR_ADDR_R_NACK = 0x48, 67 MR_DATA_R_ACK = 0x50, 68 MR_DATA_R_NACK = 0x58, 69 M_I2C_IDLE = 0xf8, 70 }; 71 72 struct lpc2k_i2c { 73 void __iomem *base; 74 struct clk *clk; 75 int irq; 76 wait_queue_head_t wait; 77 struct i2c_adapter adap; 78 struct i2c_msg *msg; 79 int msg_idx; 80 int msg_status; 81 int is_last; 82 }; 83 84 static void i2c_lpc2k_reset(struct lpc2k_i2c *i2c) 85 { 86 /* Will force clear all statuses */ 87 writel(LPC24XX_CLEAR_ALL, i2c->base + LPC24XX_I2CONCLR); 88 writel(0, i2c->base + LPC24XX_I2ADDR); 89 writel(LPC24XX_I2EN, i2c->base + LPC24XX_I2CONSET); 90 } 91 92 static int i2c_lpc2k_clear_arb(struct lpc2k_i2c *i2c) 93 { 94 unsigned long timeout = jiffies + msecs_to_jiffies(1000); 95 96 /* 97 * If the transfer needs to abort for some reason, we'll try to 98 * force a stop condition to clear any pending bus conditions 99 */ 100 writel(LPC24XX_STO, i2c->base + LPC24XX_I2CONSET); 101 102 /* Wait for status change */ 103 while (readl(i2c->base + LPC24XX_I2STAT) != M_I2C_IDLE) { 104 if (time_after(jiffies, timeout)) { 105 /* Bus was not idle, try to reset adapter */ 106 i2c_lpc2k_reset(i2c); 107 return -EBUSY; 108 } 109 110 cpu_relax(); 111 } 112 113 return 0; 114 } 115 116 static void i2c_lpc2k_pump_msg(struct lpc2k_i2c *i2c) 117 { 118 unsigned char data; 119 u32 status; 120 121 /* 122 * I2C in the LPC2xxx series is basically a state machine. 123 * Just run through the steps based on the current status. 124 */ 125 status = readl(i2c->base + LPC24XX_I2STAT); 126 127 switch (status) { 128 case M_START: 129 case M_REPSTART: 130 /* Start bit was just sent out, send out addr and dir */ 131 data = i2c_8bit_addr_from_msg(i2c->msg); 132 133 writel(data, i2c->base + LPC24XX_I2DAT); 134 writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR); 135 break; 136 137 case MX_ADDR_W_ACK: 138 case MX_DATA_W_ACK: 139 /* 140 * Address or data was sent out with an ACK. If there is more 141 * data to send, send it now 142 */ 143 if (i2c->msg_idx < i2c->msg->len) { 144 writel(i2c->msg->buf[i2c->msg_idx], 145 i2c->base + LPC24XX_I2DAT); 146 } else if (i2c->is_last) { 147 /* Last message, send stop */ 148 writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET); 149 writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); 150 i2c->msg_status = 0; 151 disable_irq_nosync(i2c->irq); 152 } else { 153 i2c->msg_status = 0; 154 disable_irq_nosync(i2c->irq); 155 } 156 157 i2c->msg_idx++; 158 break; 159 160 case MR_ADDR_R_ACK: 161 /* Receive first byte from slave */ 162 if (i2c->msg->len == 1) { 163 /* Last byte, return NACK */ 164 writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR); 165 } else { 166 /* Not last byte, return ACK */ 167 writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET); 168 } 169 170 writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR); 171 break; 172 173 case MR_DATA_R_NACK: 174 /* 175 * The I2C shows NACK status on reads, so we need to accept 176 * the NACK as an ACK here. This should be ok, as the real 177 * BACK would of been caught on the address write. 178 */ 179 case MR_DATA_R_ACK: 180 /* Data was received */ 181 if (i2c->msg_idx < i2c->msg->len) { 182 i2c->msg->buf[i2c->msg_idx] = 183 readl(i2c->base + LPC24XX_I2DAT); 184 } 185 186 /* If transfer is done, send STOP */ 187 if (i2c->msg_idx >= i2c->msg->len - 1 && i2c->is_last) { 188 writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET); 189 writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); 190 i2c->msg_status = 0; 191 } 192 193 /* Message is done */ 194 if (i2c->msg_idx >= i2c->msg->len - 1) { 195 i2c->msg_status = 0; 196 disable_irq_nosync(i2c->irq); 197 } 198 199 /* 200 * One pre-last data input, send NACK to tell the slave that 201 * this is going to be the last data byte to be transferred. 202 */ 203 if (i2c->msg_idx >= i2c->msg->len - 2) { 204 /* One byte left to receive - NACK */ 205 writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR); 206 } else { 207 /* More than one byte left to receive - ACK */ 208 writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET); 209 } 210 211 writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR); 212 i2c->msg_idx++; 213 break; 214 215 case MX_ADDR_W_NACK: 216 case MX_DATA_W_NACK: 217 case MR_ADDR_R_NACK: 218 /* NACK processing is done */ 219 writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET); 220 i2c->msg_status = -ENXIO; 221 disable_irq_nosync(i2c->irq); 222 break; 223 224 case M_DATA_ARB_LOST: 225 /* Arbitration lost */ 226 i2c->msg_status = -EAGAIN; 227 228 /* Release the I2C bus */ 229 writel(LPC24XX_STA | LPC24XX_STO, i2c->base + LPC24XX_I2CONCLR); 230 disable_irq_nosync(i2c->irq); 231 break; 232 233 default: 234 /* Unexpected statuses */ 235 i2c->msg_status = -EIO; 236 disable_irq_nosync(i2c->irq); 237 break; 238 } 239 240 /* Exit on failure or all bytes transferred */ 241 if (i2c->msg_status != -EBUSY) 242 wake_up(&i2c->wait); 243 244 /* 245 * If `msg_status` is zero, then `lpc2k_process_msg()` 246 * is responsible for clearing the SI flag. 247 */ 248 if (i2c->msg_status != 0) 249 writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); 250 } 251 252 static int lpc2k_process_msg(struct lpc2k_i2c *i2c, int msgidx) 253 { 254 /* A new transfer is kicked off by initiating a start condition */ 255 if (!msgidx) { 256 writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET); 257 } else { 258 /* 259 * A multi-message I2C transfer continues where the 260 * previous I2C transfer left off and uses the 261 * current condition of the I2C adapter. 262 */ 263 if (unlikely(i2c->msg->flags & I2C_M_NOSTART)) { 264 WARN_ON(i2c->msg->len == 0); 265 266 if (!(i2c->msg->flags & I2C_M_RD)) { 267 /* Start transmit of data */ 268 writel(i2c->msg->buf[0], 269 i2c->base + LPC24XX_I2DAT); 270 i2c->msg_idx++; 271 } 272 } else { 273 /* Start or repeated start */ 274 writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET); 275 } 276 277 writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); 278 } 279 280 enable_irq(i2c->irq); 281 282 /* Wait for transfer completion */ 283 if (wait_event_timeout(i2c->wait, i2c->msg_status != -EBUSY, 284 msecs_to_jiffies(1000)) == 0) { 285 disable_irq_nosync(i2c->irq); 286 287 return -ETIMEDOUT; 288 } 289 290 return i2c->msg_status; 291 } 292 293 static int i2c_lpc2k_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, 294 int msg_num) 295 { 296 struct lpc2k_i2c *i2c = i2c_get_adapdata(adap); 297 int ret, i; 298 u32 stat; 299 300 /* Check for bus idle condition */ 301 stat = readl(i2c->base + LPC24XX_I2STAT); 302 if (stat != M_I2C_IDLE) { 303 /* Something is holding the bus, try to clear it */ 304 return i2c_lpc2k_clear_arb(i2c); 305 } 306 307 /* Process a single message at a time */ 308 for (i = 0; i < msg_num; i++) { 309 /* Save message pointer and current message data index */ 310 i2c->msg = &msgs[i]; 311 i2c->msg_idx = 0; 312 i2c->msg_status = -EBUSY; 313 i2c->is_last = (i == (msg_num - 1)); 314 315 ret = lpc2k_process_msg(i2c, i); 316 if (ret) 317 return ret; 318 } 319 320 return msg_num; 321 } 322 323 static irqreturn_t i2c_lpc2k_handler(int irq, void *dev_id) 324 { 325 struct lpc2k_i2c *i2c = dev_id; 326 327 if (readl(i2c->base + LPC24XX_I2CONSET) & LPC24XX_SI) { 328 i2c_lpc2k_pump_msg(i2c); 329 return IRQ_HANDLED; 330 } 331 332 return IRQ_NONE; 333 } 334 335 static u32 i2c_lpc2k_functionality(struct i2c_adapter *adap) 336 { 337 /* Only emulated SMBus for now */ 338 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 339 } 340 341 static const struct i2c_algorithm i2c_lpc2k_algorithm = { 342 .master_xfer = i2c_lpc2k_xfer, 343 .functionality = i2c_lpc2k_functionality, 344 }; 345 346 static int i2c_lpc2k_probe(struct platform_device *pdev) 347 { 348 struct lpc2k_i2c *i2c; 349 u32 bus_clk_rate; 350 u32 scl_high; 351 u32 clkrate; 352 int ret; 353 354 i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL); 355 if (!i2c) 356 return -ENOMEM; 357 358 i2c->base = devm_platform_ioremap_resource(pdev, 0); 359 if (IS_ERR(i2c->base)) 360 return PTR_ERR(i2c->base); 361 362 i2c->irq = platform_get_irq(pdev, 0); 363 if (i2c->irq < 0) 364 return i2c->irq; 365 366 init_waitqueue_head(&i2c->wait); 367 368 i2c->clk = devm_clk_get_enabled(&pdev->dev, NULL); 369 if (IS_ERR(i2c->clk)) { 370 dev_err(&pdev->dev, "failed to enable clock.\n"); 371 return PTR_ERR(i2c->clk); 372 } 373 374 ret = devm_request_irq(&pdev->dev, i2c->irq, i2c_lpc2k_handler, 0, 375 dev_name(&pdev->dev), i2c); 376 if (ret < 0) { 377 dev_err(&pdev->dev, "can't request interrupt.\n"); 378 return ret; 379 } 380 381 disable_irq_nosync(i2c->irq); 382 383 /* Place controller is a known state */ 384 i2c_lpc2k_reset(i2c); 385 386 ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", 387 &bus_clk_rate); 388 if (ret) 389 bus_clk_rate = I2C_MAX_STANDARD_MODE_FREQ; 390 391 clkrate = clk_get_rate(i2c->clk); 392 if (clkrate == 0) { 393 dev_err(&pdev->dev, "can't get I2C base clock\n"); 394 return -EINVAL; 395 } 396 397 /* Setup I2C dividers to generate clock with proper duty cycle */ 398 clkrate = clkrate / bus_clk_rate; 399 if (bus_clk_rate <= I2C_MAX_STANDARD_MODE_FREQ) 400 scl_high = (clkrate * I2C_STD_MODE_DUTY) / 100; 401 else if (bus_clk_rate <= I2C_MAX_FAST_MODE_FREQ) 402 scl_high = (clkrate * I2C_FAST_MODE_DUTY) / 100; 403 else 404 scl_high = (clkrate * I2C_FAST_MODE_PLUS_DUTY) / 100; 405 406 writel(scl_high, i2c->base + LPC24XX_I2SCLH); 407 writel(clkrate - scl_high, i2c->base + LPC24XX_I2SCLL); 408 409 platform_set_drvdata(pdev, i2c); 410 411 i2c_set_adapdata(&i2c->adap, i2c); 412 i2c->adap.owner = THIS_MODULE; 413 strscpy(i2c->adap.name, "LPC2K I2C adapter", sizeof(i2c->adap.name)); 414 i2c->adap.algo = &i2c_lpc2k_algorithm; 415 i2c->adap.dev.parent = &pdev->dev; 416 i2c->adap.dev.of_node = pdev->dev.of_node; 417 418 ret = i2c_add_adapter(&i2c->adap); 419 if (ret < 0) 420 return ret; 421 422 dev_info(&pdev->dev, "LPC2K I2C adapter\n"); 423 424 return 0; 425 } 426 427 static void i2c_lpc2k_remove(struct platform_device *dev) 428 { 429 struct lpc2k_i2c *i2c = platform_get_drvdata(dev); 430 431 i2c_del_adapter(&i2c->adap); 432 } 433 434 #ifdef CONFIG_PM 435 static int i2c_lpc2k_suspend(struct device *dev) 436 { 437 struct lpc2k_i2c *i2c = dev_get_drvdata(dev); 438 439 clk_disable(i2c->clk); 440 441 return 0; 442 } 443 444 static int i2c_lpc2k_resume(struct device *dev) 445 { 446 struct lpc2k_i2c *i2c = dev_get_drvdata(dev); 447 448 clk_enable(i2c->clk); 449 i2c_lpc2k_reset(i2c); 450 451 return 0; 452 } 453 454 static const struct dev_pm_ops i2c_lpc2k_dev_pm_ops = { 455 .suspend_noirq = i2c_lpc2k_suspend, 456 .resume_noirq = i2c_lpc2k_resume, 457 }; 458 459 #define I2C_LPC2K_DEV_PM_OPS (&i2c_lpc2k_dev_pm_ops) 460 #else 461 #define I2C_LPC2K_DEV_PM_OPS NULL 462 #endif 463 464 static const struct of_device_id lpc2k_i2c_match[] = { 465 { .compatible = "nxp,lpc1788-i2c" }, 466 {}, 467 }; 468 MODULE_DEVICE_TABLE(of, lpc2k_i2c_match); 469 470 static struct platform_driver i2c_lpc2k_driver = { 471 .probe = i2c_lpc2k_probe, 472 .remove_new = i2c_lpc2k_remove, 473 .driver = { 474 .name = "lpc2k-i2c", 475 .pm = I2C_LPC2K_DEV_PM_OPS, 476 .of_match_table = lpc2k_i2c_match, 477 }, 478 }; 479 module_platform_driver(i2c_lpc2k_driver); 480 481 MODULE_AUTHOR("Kevin Wells <kevin.wells@nxp.com>"); 482 MODULE_DESCRIPTION("I2C driver for LPC2xxx devices"); 483 MODULE_LICENSE("GPL"); 484 MODULE_ALIAS("platform:lpc2k-i2c"); 485