1 /* 2 * SPI_PPC4XX SPI controller driver. 3 * 4 * Copyright (C) 2007 Gary Jennejohn <garyj@denx.de> 5 * Copyright 2008 Stefan Roese <sr@denx.de>, DENX Software Engineering 6 * Copyright 2009 Harris Corporation, Steven A. Falco <sfalco@harris.com> 7 * 8 * Based in part on drivers/spi/spi_s3c24xx.c 9 * 10 * Copyright (c) 2006 Ben Dooks 11 * Copyright (c) 2006 Simtec Electronics 12 * Ben Dooks <ben@simtec.co.uk> 13 * 14 * This program is free software; you can redistribute it and/or modify it 15 * under the terms of the GNU General Public License version 2 as published 16 * by the Free Software Foundation. 17 */ 18 19 /* 20 * The PPC4xx SPI controller has no FIFO so each sent/received byte will 21 * generate an interrupt to the CPU. This can cause high CPU utilization. 22 * This driver allows platforms to reduce the interrupt load on the CPU 23 * during SPI transfers by setting max_speed_hz via the device tree. 24 */ 25 26 #include <linux/module.h> 27 #include <linux/init.h> 28 #include <linux/sched.h> 29 #include <linux/slab.h> 30 #include <linux/errno.h> 31 #include <linux/wait.h> 32 #include <linux/of_platform.h> 33 #include <linux/of_spi.h> 34 #include <linux/of_gpio.h> 35 #include <linux/interrupt.h> 36 #include <linux/delay.h> 37 38 #include <linux/gpio.h> 39 #include <linux/spi/spi.h> 40 #include <linux/spi/spi_bitbang.h> 41 42 #include <asm/io.h> 43 #include <asm/dcr.h> 44 #include <asm/dcr-regs.h> 45 46 /* bits in mode register - bit 0 is MSb */ 47 48 /* 49 * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock" 50 * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock" 51 * Note: This is the inverse of CPHA. 52 */ 53 #define SPI_PPC4XX_MODE_SCP (0x80 >> 3) 54 55 /* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */ 56 #define SPI_PPC4XX_MODE_SPE (0x80 >> 4) 57 58 /* 59 * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode 60 * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode 61 * Note: This is identical to SPI_LSB_FIRST. 62 */ 63 #define SPI_PPC4XX_MODE_RD (0x80 >> 5) 64 65 /* 66 * SPI_PPC4XX_MODE_CI = 0 means "clock idles low" 67 * SPI_PPC4XX_MODE_CI = 1 means "clock idles high" 68 * Note: This is identical to CPOL. 69 */ 70 #define SPI_PPC4XX_MODE_CI (0x80 >> 6) 71 72 /* 73 * SPI_PPC4XX_MODE_IL = 0 means "loopback disable" 74 * SPI_PPC4XX_MODE_IL = 1 means "loopback enable" 75 */ 76 #define SPI_PPC4XX_MODE_IL (0x80 >> 7) 77 78 /* bits in control register */ 79 /* starts a transfer when set */ 80 #define SPI_PPC4XX_CR_STR (0x80 >> 7) 81 82 /* bits in status register */ 83 /* port is busy with a transfer */ 84 #define SPI_PPC4XX_SR_BSY (0x80 >> 6) 85 /* RxD ready */ 86 #define SPI_PPC4XX_SR_RBR (0x80 >> 7) 87 88 /* clock settings (SCP and CI) for various SPI modes */ 89 #define SPI_CLK_MODE0 (SPI_PPC4XX_MODE_SCP | 0) 90 #define SPI_CLK_MODE1 (0 | 0) 91 #define SPI_CLK_MODE2 (SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI) 92 #define SPI_CLK_MODE3 (0 | SPI_PPC4XX_MODE_CI) 93 94 #define DRIVER_NAME "spi_ppc4xx_of" 95 96 struct spi_ppc4xx_regs { 97 u8 mode; 98 u8 rxd; 99 u8 txd; 100 u8 cr; 101 u8 sr; 102 u8 dummy; 103 /* 104 * Clock divisor modulus register 105 * This uses the follwing formula: 106 * SCPClkOut = OPBCLK/(4(CDM + 1)) 107 * or 108 * CDM = (OPBCLK/4*SCPClkOut) - 1 109 * bit 0 is the MSb! 110 */ 111 u8 cdm; 112 }; 113 114 /* SPI Controller driver's private data. */ 115 struct ppc4xx_spi { 116 /* bitbang has to be first */ 117 struct spi_bitbang bitbang; 118 struct completion done; 119 120 u64 mapbase; 121 u64 mapsize; 122 int irqnum; 123 /* need this to set the SPI clock */ 124 unsigned int opb_freq; 125 126 /* for transfers */ 127 int len; 128 int count; 129 /* data buffers */ 130 const unsigned char *tx; 131 unsigned char *rx; 132 133 int *gpios; 134 135 struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */ 136 struct spi_master *master; 137 struct device *dev; 138 }; 139 140 /* need this so we can set the clock in the chipselect routine */ 141 struct spi_ppc4xx_cs { 142 u8 mode; 143 }; 144 145 static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t) 146 { 147 struct ppc4xx_spi *hw; 148 u8 data; 149 150 dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n", 151 t->tx_buf, t->rx_buf, t->len); 152 153 hw = spi_master_get_devdata(spi->master); 154 155 hw->tx = t->tx_buf; 156 hw->rx = t->rx_buf; 157 hw->len = t->len; 158 hw->count = 0; 159 160 /* send the first byte */ 161 data = hw->tx ? hw->tx[0] : 0; 162 out_8(&hw->regs->txd, data); 163 out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR); 164 wait_for_completion(&hw->done); 165 166 return hw->count; 167 } 168 169 static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t) 170 { 171 struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master); 172 struct spi_ppc4xx_cs *cs = spi->controller_state; 173 int scr; 174 u8 cdm = 0; 175 u32 speed; 176 u8 bits_per_word; 177 178 /* Start with the generic configuration for this device. */ 179 bits_per_word = spi->bits_per_word; 180 speed = spi->max_speed_hz; 181 182 /* 183 * Modify the configuration if the transfer overrides it. Do not allow 184 * the transfer to overwrite the generic configuration with zeros. 185 */ 186 if (t) { 187 if (t->bits_per_word) 188 bits_per_word = t->bits_per_word; 189 190 if (t->speed_hz) 191 speed = min(t->speed_hz, spi->max_speed_hz); 192 } 193 194 if (bits_per_word != 8) { 195 dev_err(&spi->dev, "invalid bits-per-word (%d)\n", 196 bits_per_word); 197 return -EINVAL; 198 } 199 200 if (!speed || (speed > spi->max_speed_hz)) { 201 dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed); 202 return -EINVAL; 203 } 204 205 /* Write new configration */ 206 out_8(&hw->regs->mode, cs->mode); 207 208 /* Set the clock */ 209 /* opb_freq was already divided by 4 */ 210 scr = (hw->opb_freq / speed) - 1; 211 if (scr > 0) 212 cdm = min(scr, 0xff); 213 214 dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed); 215 216 if (in_8(&hw->regs->cdm) != cdm) 217 out_8(&hw->regs->cdm, cdm); 218 219 spin_lock(&hw->bitbang.lock); 220 if (!hw->bitbang.busy) { 221 hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE); 222 /* Need to ndelay here? */ 223 } 224 spin_unlock(&hw->bitbang.lock); 225 226 return 0; 227 } 228 229 static int spi_ppc4xx_setup(struct spi_device *spi) 230 { 231 struct spi_ppc4xx_cs *cs = spi->controller_state; 232 233 if (spi->bits_per_word != 8) { 234 dev_err(&spi->dev, "invalid bits-per-word (%d)\n", 235 spi->bits_per_word); 236 return -EINVAL; 237 } 238 239 if (!spi->max_speed_hz) { 240 dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n"); 241 return -EINVAL; 242 } 243 244 if (cs == NULL) { 245 cs = kzalloc(sizeof *cs, GFP_KERNEL); 246 if (!cs) 247 return -ENOMEM; 248 spi->controller_state = cs; 249 } 250 251 /* 252 * We set all bits of the SPI0_MODE register, so, 253 * no need to read-modify-write 254 */ 255 cs->mode = SPI_PPC4XX_MODE_SPE; 256 257 switch (spi->mode & (SPI_CPHA | SPI_CPOL)) { 258 case SPI_MODE_0: 259 cs->mode |= SPI_CLK_MODE0; 260 break; 261 case SPI_MODE_1: 262 cs->mode |= SPI_CLK_MODE1; 263 break; 264 case SPI_MODE_2: 265 cs->mode |= SPI_CLK_MODE2; 266 break; 267 case SPI_MODE_3: 268 cs->mode |= SPI_CLK_MODE3; 269 break; 270 } 271 272 if (spi->mode & SPI_LSB_FIRST) 273 cs->mode |= SPI_PPC4XX_MODE_RD; 274 275 return 0; 276 } 277 278 static void spi_ppc4xx_chipsel(struct spi_device *spi, int value) 279 { 280 struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master); 281 unsigned int cs = spi->chip_select; 282 unsigned int cspol; 283 284 /* 285 * If there are no chip selects at all, or if this is the special 286 * case of a non-existent (dummy) chip select, do nothing. 287 */ 288 289 if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST) 290 return; 291 292 cspol = spi->mode & SPI_CS_HIGH ? 1 : 0; 293 if (value == BITBANG_CS_INACTIVE) 294 cspol = !cspol; 295 296 gpio_set_value(hw->gpios[cs], cspol); 297 } 298 299 static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id) 300 { 301 struct ppc4xx_spi *hw; 302 u8 status; 303 u8 data; 304 unsigned int count; 305 306 hw = (struct ppc4xx_spi *)dev_id; 307 308 status = in_8(&hw->regs->sr); 309 if (!status) 310 return IRQ_NONE; 311 312 /* 313 * BSY de-asserts one cycle after the transfer is complete. The 314 * interrupt is asserted after the transfer is complete. The exact 315 * relationship is not documented, hence this code. 316 */ 317 318 if (unlikely(status & SPI_PPC4XX_SR_BSY)) { 319 u8 lstatus; 320 int cnt = 0; 321 322 dev_dbg(hw->dev, "got interrupt but spi still busy?\n"); 323 do { 324 ndelay(10); 325 lstatus = in_8(&hw->regs->sr); 326 } while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY); 327 328 if (cnt >= 100) { 329 dev_err(hw->dev, "busywait: too many loops!\n"); 330 complete(&hw->done); 331 return IRQ_HANDLED; 332 } else { 333 /* status is always 1 (RBR) here */ 334 status = in_8(&hw->regs->sr); 335 dev_dbg(hw->dev, "loops %d status %x\n", cnt, status); 336 } 337 } 338 339 count = hw->count; 340 hw->count++; 341 342 /* RBR triggered this interrupt. Therefore, data must be ready. */ 343 data = in_8(&hw->regs->rxd); 344 if (hw->rx) 345 hw->rx[count] = data; 346 347 count++; 348 349 if (count < hw->len) { 350 data = hw->tx ? hw->tx[count] : 0; 351 out_8(&hw->regs->txd, data); 352 out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR); 353 } else { 354 complete(&hw->done); 355 } 356 357 return IRQ_HANDLED; 358 } 359 360 static void spi_ppc4xx_cleanup(struct spi_device *spi) 361 { 362 kfree(spi->controller_state); 363 } 364 365 static void spi_ppc4xx_enable(struct ppc4xx_spi *hw) 366 { 367 /* 368 * On all 4xx PPC's the SPI bus is shared/multiplexed with 369 * the 2nd I2C bus. We need to enable the the SPI bus before 370 * using it. 371 */ 372 373 /* need to clear bit 14 to enable SPC */ 374 dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0); 375 } 376 377 static void free_gpios(struct ppc4xx_spi *hw) 378 { 379 if (hw->master->num_chipselect) { 380 int i; 381 for (i = 0; i < hw->master->num_chipselect; i++) 382 if (gpio_is_valid(hw->gpios[i])) 383 gpio_free(hw->gpios[i]); 384 385 kfree(hw->gpios); 386 hw->gpios = NULL; 387 } 388 } 389 390 /* 391 * platform_device layer stuff... 392 */ 393 static int __init spi_ppc4xx_of_probe(struct platform_device *op) 394 { 395 struct ppc4xx_spi *hw; 396 struct spi_master *master; 397 struct spi_bitbang *bbp; 398 struct resource resource; 399 struct device_node *np = op->dev.of_node; 400 struct device *dev = &op->dev; 401 struct device_node *opbnp; 402 int ret; 403 int num_gpios; 404 const unsigned int *clk; 405 406 master = spi_alloc_master(dev, sizeof *hw); 407 if (master == NULL) 408 return -ENOMEM; 409 master->dev.of_node = np; 410 dev_set_drvdata(dev, master); 411 hw = spi_master_get_devdata(master); 412 hw->master = spi_master_get(master); 413 hw->dev = dev; 414 415 init_completion(&hw->done); 416 417 /* 418 * A count of zero implies a single SPI device without any chip-select. 419 * Note that of_gpio_count counts all gpios assigned to this spi master. 420 * This includes both "null" gpio's and real ones. 421 */ 422 num_gpios = of_gpio_count(np); 423 if (num_gpios) { 424 int i; 425 426 hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL); 427 if (!hw->gpios) { 428 ret = -ENOMEM; 429 goto free_master; 430 } 431 432 for (i = 0; i < num_gpios; i++) { 433 int gpio; 434 enum of_gpio_flags flags; 435 436 gpio = of_get_gpio_flags(np, i, &flags); 437 hw->gpios[i] = gpio; 438 439 if (gpio_is_valid(gpio)) { 440 /* Real CS - set the initial state. */ 441 ret = gpio_request(gpio, np->name); 442 if (ret < 0) { 443 dev_err(dev, "can't request gpio " 444 "#%d: %d\n", i, ret); 445 goto free_gpios; 446 } 447 448 gpio_direction_output(gpio, 449 !!(flags & OF_GPIO_ACTIVE_LOW)); 450 } else if (gpio == -EEXIST) { 451 ; /* No CS, but that's OK. */ 452 } else { 453 dev_err(dev, "invalid gpio #%d: %d\n", i, gpio); 454 ret = -EINVAL; 455 goto free_gpios; 456 } 457 } 458 } 459 460 /* Setup the state for the bitbang driver */ 461 bbp = &hw->bitbang; 462 bbp->master = hw->master; 463 bbp->setup_transfer = spi_ppc4xx_setupxfer; 464 bbp->chipselect = spi_ppc4xx_chipsel; 465 bbp->txrx_bufs = spi_ppc4xx_txrx; 466 bbp->use_dma = 0; 467 bbp->master->setup = spi_ppc4xx_setup; 468 bbp->master->cleanup = spi_ppc4xx_cleanup; 469 470 /* Allocate bus num dynamically. */ 471 bbp->master->bus_num = -1; 472 473 /* the spi->mode bits understood by this driver: */ 474 bbp->master->mode_bits = 475 SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST; 476 477 /* this many pins in all GPIO controllers */ 478 bbp->master->num_chipselect = num_gpios; 479 480 /* Get the clock for the OPB */ 481 opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb"); 482 if (opbnp == NULL) { 483 dev_err(dev, "OPB: cannot find node\n"); 484 ret = -ENODEV; 485 goto free_gpios; 486 } 487 /* Get the clock (Hz) for the OPB */ 488 clk = of_get_property(opbnp, "clock-frequency", NULL); 489 if (clk == NULL) { 490 dev_err(dev, "OPB: no clock-frequency property set\n"); 491 of_node_put(opbnp); 492 ret = -ENODEV; 493 goto free_gpios; 494 } 495 hw->opb_freq = *clk; 496 hw->opb_freq >>= 2; 497 of_node_put(opbnp); 498 499 ret = of_address_to_resource(np, 0, &resource); 500 if (ret) { 501 dev_err(dev, "error while parsing device node resource\n"); 502 goto free_gpios; 503 } 504 hw->mapbase = resource.start; 505 hw->mapsize = resource_size(&resource); 506 507 /* Sanity check */ 508 if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) { 509 dev_err(dev, "too small to map registers\n"); 510 ret = -EINVAL; 511 goto free_gpios; 512 } 513 514 /* Request IRQ */ 515 hw->irqnum = irq_of_parse_and_map(np, 0); 516 ret = request_irq(hw->irqnum, spi_ppc4xx_int, 517 IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw); 518 if (ret) { 519 dev_err(dev, "unable to allocate interrupt\n"); 520 goto free_gpios; 521 } 522 523 if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) { 524 dev_err(dev, "resource unavailable\n"); 525 ret = -EBUSY; 526 goto request_mem_error; 527 } 528 529 hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs)); 530 531 if (!hw->regs) { 532 dev_err(dev, "unable to memory map registers\n"); 533 ret = -ENXIO; 534 goto map_io_error; 535 } 536 537 spi_ppc4xx_enable(hw); 538 539 /* Finally register our spi controller */ 540 dev->dma_mask = 0; 541 ret = spi_bitbang_start(bbp); 542 if (ret) { 543 dev_err(dev, "failed to register SPI master\n"); 544 goto unmap_regs; 545 } 546 547 dev_info(dev, "driver initialized\n"); 548 549 return 0; 550 551 unmap_regs: 552 iounmap(hw->regs); 553 map_io_error: 554 release_mem_region(hw->mapbase, hw->mapsize); 555 request_mem_error: 556 free_irq(hw->irqnum, hw); 557 free_gpios: 558 free_gpios(hw); 559 free_master: 560 dev_set_drvdata(dev, NULL); 561 spi_master_put(master); 562 563 dev_err(dev, "initialization failed\n"); 564 return ret; 565 } 566 567 static int __exit spi_ppc4xx_of_remove(struct platform_device *op) 568 { 569 struct spi_master *master = dev_get_drvdata(&op->dev); 570 struct ppc4xx_spi *hw = spi_master_get_devdata(master); 571 572 spi_bitbang_stop(&hw->bitbang); 573 dev_set_drvdata(&op->dev, NULL); 574 release_mem_region(hw->mapbase, hw->mapsize); 575 free_irq(hw->irqnum, hw); 576 iounmap(hw->regs); 577 free_gpios(hw); 578 return 0; 579 } 580 581 static const struct of_device_id spi_ppc4xx_of_match[] = { 582 { .compatible = "ibm,ppc4xx-spi", }, 583 {}, 584 }; 585 586 MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match); 587 588 static struct platform_driver spi_ppc4xx_of_driver = { 589 .probe = spi_ppc4xx_of_probe, 590 .remove = __exit_p(spi_ppc4xx_of_remove), 591 .driver = { 592 .name = DRIVER_NAME, 593 .owner = THIS_MODULE, 594 .of_match_table = spi_ppc4xx_of_match, 595 }, 596 }; 597 598 static int __init spi_ppc4xx_init(void) 599 { 600 return platform_driver_register(&spi_ppc4xx_of_driver); 601 } 602 module_init(spi_ppc4xx_init); 603 604 static void __exit spi_ppc4xx_exit(void) 605 { 606 platform_driver_unregister(&spi_ppc4xx_of_driver); 607 } 608 module_exit(spi_ppc4xx_exit); 609 610 MODULE_AUTHOR("Gary Jennejohn & Stefan Roese"); 611 MODULE_DESCRIPTION("Simple PPC4xx SPI Driver"); 612 MODULE_LICENSE("GPL"); 613