1 /* 2 * MPC52xx SPI bus driver. 3 * 4 * Copyright (C) 2008 Secret Lab Technologies Ltd. 5 * 6 * This file is released under the GPLv2 7 * 8 * This is the driver for the MPC5200's dedicated SPI controller. 9 * 10 * Note: this driver does not support the MPC5200 PSC in SPI mode. For 11 * that driver see drivers/spi/mpc52xx_psc_spi.c 12 */ 13 14 #include <linux/module.h> 15 #include <linux/errno.h> 16 #include <linux/of_platform.h> 17 #include <linux/interrupt.h> 18 #include <linux/delay.h> 19 #include <linux/spi/spi.h> 20 #include <linux/io.h> 21 #include <linux/of_gpio.h> 22 #include <linux/slab.h> 23 #include <asm/time.h> 24 #include <asm/mpc52xx.h> 25 26 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 27 MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver"); 28 MODULE_LICENSE("GPL"); 29 30 /* Register offsets */ 31 #define SPI_CTRL1 0x00 32 #define SPI_CTRL1_SPIE (1 << 7) 33 #define SPI_CTRL1_SPE (1 << 6) 34 #define SPI_CTRL1_MSTR (1 << 4) 35 #define SPI_CTRL1_CPOL (1 << 3) 36 #define SPI_CTRL1_CPHA (1 << 2) 37 #define SPI_CTRL1_SSOE (1 << 1) 38 #define SPI_CTRL1_LSBFE (1 << 0) 39 40 #define SPI_CTRL2 0x01 41 #define SPI_BRR 0x04 42 43 #define SPI_STATUS 0x05 44 #define SPI_STATUS_SPIF (1 << 7) 45 #define SPI_STATUS_WCOL (1 << 6) 46 #define SPI_STATUS_MODF (1 << 4) 47 48 #define SPI_DATA 0x09 49 #define SPI_PORTDATA 0x0d 50 #define SPI_DATADIR 0x10 51 52 /* FSM state return values */ 53 #define FSM_STOP 0 /* Nothing more for the state machine to */ 54 /* do. If something interesting happens */ 55 /* then an IRQ will be received */ 56 #define FSM_POLL 1 /* need to poll for completion, an IRQ is */ 57 /* not expected */ 58 #define FSM_CONTINUE 2 /* Keep iterating the state machine */ 59 60 /* Driver internal data */ 61 struct mpc52xx_spi { 62 struct spi_master *master; 63 void __iomem *regs; 64 int irq0; /* MODF irq */ 65 int irq1; /* SPIF irq */ 66 unsigned int ipb_freq; 67 68 /* Statistics; not used now, but will be reintroduced for debugfs */ 69 int msg_count; 70 int wcol_count; 71 int wcol_ticks; 72 u32 wcol_tx_timestamp; 73 int modf_count; 74 int byte_count; 75 76 struct list_head queue; /* queue of pending messages */ 77 spinlock_t lock; 78 struct work_struct work; 79 80 /* Details of current transfer (length, and buffer pointers) */ 81 struct spi_message *message; /* current message */ 82 struct spi_transfer *transfer; /* current transfer */ 83 int (*state)(int irq, struct mpc52xx_spi *ms, u8 status, u8 data); 84 int len; 85 int timestamp; 86 u8 *rx_buf; 87 const u8 *tx_buf; 88 int cs_change; 89 int gpio_cs_count; 90 unsigned int *gpio_cs; 91 }; 92 93 /* 94 * CS control function 95 */ 96 static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value) 97 { 98 int cs; 99 100 if (ms->gpio_cs_count > 0) { 101 cs = ms->message->spi->chip_select; 102 gpio_set_value(ms->gpio_cs[cs], value ? 0 : 1); 103 } else 104 out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08); 105 } 106 107 /* 108 * Start a new transfer. This is called both by the idle state 109 * for the first transfer in a message, and by the wait state when the 110 * previous transfer in a message is complete. 111 */ 112 static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms) 113 { 114 ms->rx_buf = ms->transfer->rx_buf; 115 ms->tx_buf = ms->transfer->tx_buf; 116 ms->len = ms->transfer->len; 117 118 /* Activate the chip select */ 119 if (ms->cs_change) 120 mpc52xx_spi_chipsel(ms, 1); 121 ms->cs_change = ms->transfer->cs_change; 122 123 /* Write out the first byte */ 124 ms->wcol_tx_timestamp = get_tbl(); 125 if (ms->tx_buf) 126 out_8(ms->regs + SPI_DATA, *ms->tx_buf++); 127 else 128 out_8(ms->regs + SPI_DATA, 0); 129 } 130 131 /* Forward declaration of state handlers */ 132 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms, 133 u8 status, u8 data); 134 static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, 135 u8 status, u8 data); 136 137 /* 138 * IDLE state 139 * 140 * No transfers are in progress; if another transfer is pending then retrieve 141 * it and kick it off. Otherwise, stop processing the state machine 142 */ 143 static int 144 mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data) 145 { 146 struct spi_device *spi; 147 int spr, sppr; 148 u8 ctrl1; 149 150 if (status && (irq != NO_IRQ)) 151 dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n", 152 status); 153 154 /* Check if there is another transfer waiting. */ 155 if (list_empty(&ms->queue)) 156 return FSM_STOP; 157 158 /* get the head of the queue */ 159 ms->message = list_first_entry(&ms->queue, struct spi_message, queue); 160 list_del_init(&ms->message->queue); 161 162 /* Setup the controller parameters */ 163 ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR; 164 spi = ms->message->spi; 165 if (spi->mode & SPI_CPHA) 166 ctrl1 |= SPI_CTRL1_CPHA; 167 if (spi->mode & SPI_CPOL) 168 ctrl1 |= SPI_CTRL1_CPOL; 169 if (spi->mode & SPI_LSB_FIRST) 170 ctrl1 |= SPI_CTRL1_LSBFE; 171 out_8(ms->regs + SPI_CTRL1, ctrl1); 172 173 /* Setup the controller speed */ 174 /* minimum divider is '2'. Also, add '1' to force rounding the 175 * divider up. */ 176 sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1; 177 spr = 0; 178 if (sppr < 1) 179 sppr = 1; 180 while (((sppr - 1) & ~0x7) != 0) { 181 sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */ 182 spr++; 183 } 184 sppr--; /* sppr quantity in register is offset by 1 */ 185 if (spr > 7) { 186 /* Don't overrun limits of SPI baudrate register */ 187 spr = 7; 188 sppr = 7; 189 } 190 out_8(ms->regs + SPI_BRR, sppr << 4 | spr); /* Set speed */ 191 192 ms->cs_change = 1; 193 ms->transfer = container_of(ms->message->transfers.next, 194 struct spi_transfer, transfer_list); 195 196 mpc52xx_spi_start_transfer(ms); 197 ms->state = mpc52xx_spi_fsmstate_transfer; 198 199 return FSM_CONTINUE; 200 } 201 202 /* 203 * TRANSFER state 204 * 205 * In the middle of a transfer. If the SPI core has completed processing 206 * a byte, then read out the received data and write out the next byte 207 * (unless this transfer is finished; in which case go on to the wait 208 * state) 209 */ 210 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms, 211 u8 status, u8 data) 212 { 213 if (!status) 214 return ms->irq0 ? FSM_STOP : FSM_POLL; 215 216 if (status & SPI_STATUS_WCOL) { 217 /* The SPI controller is stoopid. At slower speeds, it may 218 * raise the SPIF flag before the state machine is actually 219 * finished, which causes a collision (internal to the state 220 * machine only). The manual recommends inserting a delay 221 * between receiving the interrupt and sending the next byte, 222 * but it can also be worked around simply by retrying the 223 * transfer which is what we do here. */ 224 ms->wcol_count++; 225 ms->wcol_ticks += get_tbl() - ms->wcol_tx_timestamp; 226 ms->wcol_tx_timestamp = get_tbl(); 227 data = 0; 228 if (ms->tx_buf) 229 data = *(ms->tx_buf - 1); 230 out_8(ms->regs + SPI_DATA, data); /* try again */ 231 return FSM_CONTINUE; 232 } else if (status & SPI_STATUS_MODF) { 233 ms->modf_count++; 234 dev_err(&ms->master->dev, "mode fault\n"); 235 mpc52xx_spi_chipsel(ms, 0); 236 ms->message->status = -EIO; 237 if (ms->message->complete) 238 ms->message->complete(ms->message->context); 239 ms->state = mpc52xx_spi_fsmstate_idle; 240 return FSM_CONTINUE; 241 } 242 243 /* Read data out of the spi device */ 244 ms->byte_count++; 245 if (ms->rx_buf) 246 *ms->rx_buf++ = data; 247 248 /* Is the transfer complete? */ 249 ms->len--; 250 if (ms->len == 0) { 251 ms->timestamp = get_tbl(); 252 ms->timestamp += ms->transfer->delay_usecs * tb_ticks_per_usec; 253 ms->state = mpc52xx_spi_fsmstate_wait; 254 return FSM_CONTINUE; 255 } 256 257 /* Write out the next byte */ 258 ms->wcol_tx_timestamp = get_tbl(); 259 if (ms->tx_buf) 260 out_8(ms->regs + SPI_DATA, *ms->tx_buf++); 261 else 262 out_8(ms->regs + SPI_DATA, 0); 263 264 return FSM_CONTINUE; 265 } 266 267 /* 268 * WAIT state 269 * 270 * A transfer has completed; need to wait for the delay period to complete 271 * before starting the next transfer 272 */ 273 static int 274 mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data) 275 { 276 if (status && irq) 277 dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n", 278 status); 279 280 if (((int)get_tbl()) - ms->timestamp < 0) 281 return FSM_POLL; 282 283 ms->message->actual_length += ms->transfer->len; 284 285 /* Check if there is another transfer in this message. If there 286 * aren't then deactivate CS, notify sender, and drop back to idle 287 * to start the next message. */ 288 if (ms->transfer->transfer_list.next == &ms->message->transfers) { 289 ms->msg_count++; 290 mpc52xx_spi_chipsel(ms, 0); 291 ms->message->status = 0; 292 if (ms->message->complete) 293 ms->message->complete(ms->message->context); 294 ms->state = mpc52xx_spi_fsmstate_idle; 295 return FSM_CONTINUE; 296 } 297 298 /* There is another transfer; kick it off */ 299 300 if (ms->cs_change) 301 mpc52xx_spi_chipsel(ms, 0); 302 303 ms->transfer = container_of(ms->transfer->transfer_list.next, 304 struct spi_transfer, transfer_list); 305 mpc52xx_spi_start_transfer(ms); 306 ms->state = mpc52xx_spi_fsmstate_transfer; 307 return FSM_CONTINUE; 308 } 309 310 /** 311 * mpc52xx_spi_fsm_process - Finite State Machine iteration function 312 * @irq: irq number that triggered the FSM or 0 for polling 313 * @ms: pointer to mpc52xx_spi driver data 314 */ 315 static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms) 316 { 317 int rc = FSM_CONTINUE; 318 u8 status, data; 319 320 while (rc == FSM_CONTINUE) { 321 /* Interrupt cleared by read of STATUS followed by 322 * read of DATA registers */ 323 status = in_8(ms->regs + SPI_STATUS); 324 data = in_8(ms->regs + SPI_DATA); 325 rc = ms->state(irq, ms, status, data); 326 } 327 328 if (rc == FSM_POLL) 329 schedule_work(&ms->work); 330 } 331 332 /** 333 * mpc52xx_spi_irq - IRQ handler 334 */ 335 static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms) 336 { 337 struct mpc52xx_spi *ms = _ms; 338 spin_lock(&ms->lock); 339 mpc52xx_spi_fsm_process(irq, ms); 340 spin_unlock(&ms->lock); 341 return IRQ_HANDLED; 342 } 343 344 /** 345 * mpc52xx_spi_wq - Workqueue function for polling the state machine 346 */ 347 static void mpc52xx_spi_wq(struct work_struct *work) 348 { 349 struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work); 350 unsigned long flags; 351 352 spin_lock_irqsave(&ms->lock, flags); 353 mpc52xx_spi_fsm_process(0, ms); 354 spin_unlock_irqrestore(&ms->lock, flags); 355 } 356 357 /* 358 * spi_master ops 359 */ 360 361 static int mpc52xx_spi_transfer(struct spi_device *spi, struct spi_message *m) 362 { 363 struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master); 364 unsigned long flags; 365 366 m->actual_length = 0; 367 m->status = -EINPROGRESS; 368 369 spin_lock_irqsave(&ms->lock, flags); 370 list_add_tail(&m->queue, &ms->queue); 371 spin_unlock_irqrestore(&ms->lock, flags); 372 schedule_work(&ms->work); 373 374 return 0; 375 } 376 377 /* 378 * OF Platform Bus Binding 379 */ 380 static int mpc52xx_spi_probe(struct platform_device *op) 381 { 382 struct spi_master *master; 383 struct mpc52xx_spi *ms; 384 void __iomem *regs; 385 u8 ctrl1; 386 int rc, i = 0; 387 int gpio_cs; 388 389 /* MMIO registers */ 390 dev_dbg(&op->dev, "probing mpc5200 SPI device\n"); 391 regs = of_iomap(op->dev.of_node, 0); 392 if (!regs) 393 return -ENODEV; 394 395 /* initialize the device */ 396 ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR; 397 out_8(regs + SPI_CTRL1, ctrl1); 398 out_8(regs + SPI_CTRL2, 0x0); 399 out_8(regs + SPI_DATADIR, 0xe); /* Set output pins */ 400 out_8(regs + SPI_PORTDATA, 0x8); /* Deassert /SS signal */ 401 402 /* Clear the status register and re-read it to check for a MODF 403 * failure. This driver cannot currently handle multiple masters 404 * on the SPI bus. This fault will also occur if the SPI signals 405 * are not connected to any pins (port_config setting) */ 406 in_8(regs + SPI_STATUS); 407 out_8(regs + SPI_CTRL1, ctrl1); 408 409 in_8(regs + SPI_DATA); 410 if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) { 411 dev_err(&op->dev, "mode fault; is port_config correct?\n"); 412 rc = -EIO; 413 goto err_init; 414 } 415 416 dev_dbg(&op->dev, "allocating spi_master struct\n"); 417 master = spi_alloc_master(&op->dev, sizeof *ms); 418 if (!master) { 419 rc = -ENOMEM; 420 goto err_alloc; 421 } 422 423 master->transfer = mpc52xx_spi_transfer; 424 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST; 425 master->bits_per_word_mask = SPI_BPW_MASK(8); 426 master->dev.of_node = op->dev.of_node; 427 428 platform_set_drvdata(op, master); 429 430 ms = spi_master_get_devdata(master); 431 ms->master = master; 432 ms->regs = regs; 433 ms->irq0 = irq_of_parse_and_map(op->dev.of_node, 0); 434 ms->irq1 = irq_of_parse_and_map(op->dev.of_node, 1); 435 ms->state = mpc52xx_spi_fsmstate_idle; 436 ms->ipb_freq = mpc5xxx_get_bus_frequency(op->dev.of_node); 437 ms->gpio_cs_count = of_gpio_count(op->dev.of_node); 438 if (ms->gpio_cs_count > 0) { 439 master->num_chipselect = ms->gpio_cs_count; 440 ms->gpio_cs = kmalloc(ms->gpio_cs_count * sizeof(unsigned int), 441 GFP_KERNEL); 442 if (!ms->gpio_cs) { 443 rc = -ENOMEM; 444 goto err_alloc_gpio; 445 } 446 447 for (i = 0; i < ms->gpio_cs_count; i++) { 448 gpio_cs = of_get_gpio(op->dev.of_node, i); 449 if (gpio_cs < 0) { 450 dev_err(&op->dev, 451 "could not parse the gpio field " 452 "in oftree\n"); 453 rc = -ENODEV; 454 goto err_gpio; 455 } 456 457 rc = gpio_request(gpio_cs, dev_name(&op->dev)); 458 if (rc) { 459 dev_err(&op->dev, 460 "can't request spi cs gpio #%d " 461 "on gpio line %d\n", i, gpio_cs); 462 goto err_gpio; 463 } 464 465 gpio_direction_output(gpio_cs, 1); 466 ms->gpio_cs[i] = gpio_cs; 467 } 468 } 469 470 spin_lock_init(&ms->lock); 471 INIT_LIST_HEAD(&ms->queue); 472 INIT_WORK(&ms->work, mpc52xx_spi_wq); 473 474 /* Decide if interrupts can be used */ 475 if (ms->irq0 && ms->irq1) { 476 rc = request_irq(ms->irq0, mpc52xx_spi_irq, 0, 477 "mpc5200-spi-modf", ms); 478 rc |= request_irq(ms->irq1, mpc52xx_spi_irq, 0, 479 "mpc5200-spi-spif", ms); 480 if (rc) { 481 free_irq(ms->irq0, ms); 482 free_irq(ms->irq1, ms); 483 ms->irq0 = ms->irq1 = 0; 484 } 485 } else { 486 /* operate in polled mode */ 487 ms->irq0 = ms->irq1 = 0; 488 } 489 490 if (!ms->irq0) 491 dev_info(&op->dev, "using polled mode\n"); 492 493 dev_dbg(&op->dev, "registering spi_master struct\n"); 494 rc = spi_register_master(master); 495 if (rc) 496 goto err_register; 497 498 dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n"); 499 500 return rc; 501 502 err_register: 503 dev_err(&ms->master->dev, "initialization failed\n"); 504 err_gpio: 505 while (i-- > 0) 506 gpio_free(ms->gpio_cs[i]); 507 508 kfree(ms->gpio_cs); 509 err_alloc_gpio: 510 spi_master_put(master); 511 err_alloc: 512 err_init: 513 iounmap(regs); 514 return rc; 515 } 516 517 static int mpc52xx_spi_remove(struct platform_device *op) 518 { 519 struct spi_master *master = spi_master_get(platform_get_drvdata(op)); 520 struct mpc52xx_spi *ms = spi_master_get_devdata(master); 521 int i; 522 523 free_irq(ms->irq0, ms); 524 free_irq(ms->irq1, ms); 525 526 for (i = 0; i < ms->gpio_cs_count; i++) 527 gpio_free(ms->gpio_cs[i]); 528 529 kfree(ms->gpio_cs); 530 spi_unregister_master(master); 531 iounmap(ms->regs); 532 spi_master_put(master); 533 534 return 0; 535 } 536 537 static const struct of_device_id mpc52xx_spi_match[] = { 538 { .compatible = "fsl,mpc5200-spi", }, 539 {} 540 }; 541 MODULE_DEVICE_TABLE(of, mpc52xx_spi_match); 542 543 static struct platform_driver mpc52xx_spi_of_driver = { 544 .driver = { 545 .name = "mpc52xx-spi", 546 .of_match_table = mpc52xx_spi_match, 547 }, 548 .probe = mpc52xx_spi_probe, 549 .remove = mpc52xx_spi_remove, 550 }; 551 module_platform_driver(mpc52xx_spi_of_driver); 552