blob: 80e172d3e72a7faab0064db66640c815c836e7a2 [file] [log] [blame]
Steven A. Falco44dab882009-09-22 16:45:58 -07001/*
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090029#include <linux/slab.h>
Steven A. Falco44dab882009-09-22 16:45:58 -070030#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
96struct 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. */
115struct 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 */
141struct spi_ppc4xx_cs {
142 u8 mode;
143};
144
145static 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
169static 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
229static 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
278static 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
299static 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
360static void spi_ppc4xx_cleanup(struct spi_device *spi)
361{
362 kfree(spi->controller_state);
363}
364
365static 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
377static 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/*
Grant Likely2dc11582010-08-06 09:25:50 -0600391 * platform_device layer stuff...
Steven A. Falco44dab882009-09-22 16:45:58 -0700392 */
Grant Likely2dc11582010-08-06 09:25:50 -0600393static int __init spi_ppc4xx_of_probe(struct platform_device *op,
Steven A. Falco44dab882009-09-22 16:45:58 -0700394 const struct of_device_id *match)
395{
396 struct ppc4xx_spi *hw;
397 struct spi_master *master;
398 struct spi_bitbang *bbp;
399 struct resource resource;
Grant Likelyb5355072010-05-25 23:24:02 -0600400 struct device_node *np = op->dev.of_node;
Steven A. Falco44dab882009-09-22 16:45:58 -0700401 struct device *dev = &op->dev;
402 struct device_node *opbnp;
403 int ret;
404 int num_gpios;
405 const unsigned int *clk;
406
407 master = spi_alloc_master(dev, sizeof *hw);
408 if (master == NULL)
409 return -ENOMEM;
Anatolij Gustschin12b15e82010-07-27 22:35:58 +0200410 master->dev.of_node = np;
Steven A. Falco44dab882009-09-22 16:45:58 -0700411 dev_set_drvdata(dev, master);
412 hw = spi_master_get_devdata(master);
413 hw->master = spi_master_get(master);
414 hw->dev = dev;
415
416 init_completion(&hw->done);
417
418 /*
419 * A count of zero implies a single SPI device without any chip-select.
420 * Note that of_gpio_count counts all gpios assigned to this spi master.
421 * This includes both "null" gpio's and real ones.
422 */
423 num_gpios = of_gpio_count(np);
424 if (num_gpios) {
425 int i;
426
427 hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL);
428 if (!hw->gpios) {
429 ret = -ENOMEM;
430 goto free_master;
431 }
432
433 for (i = 0; i < num_gpios; i++) {
434 int gpio;
435 enum of_gpio_flags flags;
436
437 gpio = of_get_gpio_flags(np, i, &flags);
438 hw->gpios[i] = gpio;
439
440 if (gpio_is_valid(gpio)) {
441 /* Real CS - set the initial state. */
442 ret = gpio_request(gpio, np->name);
443 if (ret < 0) {
444 dev_err(dev, "can't request gpio "
445 "#%d: %d\n", i, ret);
446 goto free_gpios;
447 }
448
449 gpio_direction_output(gpio,
450 !!(flags & OF_GPIO_ACTIVE_LOW));
451 } else if (gpio == -EEXIST) {
452 ; /* No CS, but that's OK. */
453 } else {
454 dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
455 ret = -EINVAL;
456 goto free_gpios;
457 }
458 }
459 }
460
461 /* Setup the state for the bitbang driver */
462 bbp = &hw->bitbang;
463 bbp->master = hw->master;
464 bbp->setup_transfer = spi_ppc4xx_setupxfer;
465 bbp->chipselect = spi_ppc4xx_chipsel;
466 bbp->txrx_bufs = spi_ppc4xx_txrx;
467 bbp->use_dma = 0;
468 bbp->master->setup = spi_ppc4xx_setup;
469 bbp->master->cleanup = spi_ppc4xx_cleanup;
470
471 /* Allocate bus num dynamically. */
472 bbp->master->bus_num = -1;
473
474 /* the spi->mode bits understood by this driver: */
475 bbp->master->mode_bits =
476 SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST;
477
478 /* this many pins in all GPIO controllers */
479 bbp->master->num_chipselect = num_gpios;
480
481 /* Get the clock for the OPB */
482 opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
483 if (opbnp == NULL) {
484 dev_err(dev, "OPB: cannot find node\n");
485 ret = -ENODEV;
486 goto free_gpios;
487 }
488 /* Get the clock (Hz) for the OPB */
489 clk = of_get_property(opbnp, "clock-frequency", NULL);
490 if (clk == NULL) {
491 dev_err(dev, "OPB: no clock-frequency property set\n");
492 of_node_put(opbnp);
493 ret = -ENODEV;
494 goto free_gpios;
495 }
496 hw->opb_freq = *clk;
497 hw->opb_freq >>= 2;
498 of_node_put(opbnp);
499
500 ret = of_address_to_resource(np, 0, &resource);
501 if (ret) {
502 dev_err(dev, "error while parsing device node resource\n");
503 goto free_gpios;
504 }
505 hw->mapbase = resource.start;
506 hw->mapsize = resource.end - resource.start + 1;
507
508 /* Sanity check */
509 if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
510 dev_err(dev, "too small to map registers\n");
511 ret = -EINVAL;
512 goto free_gpios;
513 }
514
515 /* Request IRQ */
516 hw->irqnum = irq_of_parse_and_map(np, 0);
517 ret = request_irq(hw->irqnum, spi_ppc4xx_int,
518 IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw);
519 if (ret) {
520 dev_err(dev, "unable to allocate interrupt\n");
521 goto free_gpios;
522 }
523
524 if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
525 dev_err(dev, "resource unavailable\n");
526 ret = -EBUSY;
527 goto request_mem_error;
528 }
529
530 hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
531
532 if (!hw->regs) {
533 dev_err(dev, "unable to memory map registers\n");
534 ret = -ENXIO;
535 goto map_io_error;
536 }
537
538 spi_ppc4xx_enable(hw);
539
540 /* Finally register our spi controller */
541 dev->dma_mask = 0;
542 ret = spi_bitbang_start(bbp);
543 if (ret) {
544 dev_err(dev, "failed to register SPI master\n");
545 goto unmap_regs;
546 }
547
548 dev_info(dev, "driver initialized\n");
Steven A. Falco44dab882009-09-22 16:45:58 -0700549
550 return 0;
551
552unmap_regs:
553 iounmap(hw->regs);
554map_io_error:
555 release_mem_region(hw->mapbase, hw->mapsize);
556request_mem_error:
557 free_irq(hw->irqnum, hw);
558free_gpios:
559 free_gpios(hw);
560free_master:
561 dev_set_drvdata(dev, NULL);
562 spi_master_put(master);
563
564 dev_err(dev, "initialization failed\n");
565 return ret;
566}
567
Grant Likely2dc11582010-08-06 09:25:50 -0600568static int __exit spi_ppc4xx_of_remove(struct platform_device *op)
Steven A. Falco44dab882009-09-22 16:45:58 -0700569{
570 struct spi_master *master = dev_get_drvdata(&op->dev);
571 struct ppc4xx_spi *hw = spi_master_get_devdata(master);
572
573 spi_bitbang_stop(&hw->bitbang);
574 dev_set_drvdata(&op->dev, NULL);
575 release_mem_region(hw->mapbase, hw->mapsize);
576 free_irq(hw->irqnum, hw);
577 iounmap(hw->regs);
578 free_gpios(hw);
579 return 0;
580}
581
Márton Németh631e61b2010-01-20 13:49:44 -0700582static const struct of_device_id spi_ppc4xx_of_match[] = {
Steven A. Falco44dab882009-09-22 16:45:58 -0700583 { .compatible = "ibm,ppc4xx-spi", },
584 {},
585};
586
587MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
588
589static struct of_platform_driver spi_ppc4xx_of_driver = {
Steven A. Falco44dab882009-09-22 16:45:58 -0700590 .probe = spi_ppc4xx_of_probe,
591 .remove = __exit_p(spi_ppc4xx_of_remove),
592 .driver = {
593 .name = DRIVER_NAME,
594 .owner = THIS_MODULE,
Grant Likely40182942010-04-13 16:13:02 -0700595 .of_match_table = spi_ppc4xx_of_match,
Steven A. Falco44dab882009-09-22 16:45:58 -0700596 },
597};
598
599static int __init spi_ppc4xx_init(void)
600{
601 return of_register_platform_driver(&spi_ppc4xx_of_driver);
602}
603module_init(spi_ppc4xx_init);
604
605static void __exit spi_ppc4xx_exit(void)
606{
607 of_unregister_platform_driver(&spi_ppc4xx_of_driver);
608}
609module_exit(spi_ppc4xx_exit);
610
611MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
612MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
613MODULE_LICENSE("GPL");