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authorSteven A. Falco <sfalco@harris.com>2009-09-22 19:45:58 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 10:39:43 -0400
commit44dab88e7cc99d1d2caa9a8936e09d9a98a6761a (patch)
tree412611ccdccc4e9dd348f1568bc3ed8055720fff /drivers/spi/spi_ppc4xx.c
parent7a8fa725b21ae19a3d9a2de196a440da8c9085a6 (diff)
spi: add spi_ppc4xx driver
This adds a SPI driver for the SPI controller found in the IBM/AMCC 4xx PowerPC's. Signed-off-by: Stefan Roese <sr@denx.de> Signed-off-by: Wolfgang Ocker <weo@reccoware.de> Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com> Signed-off-by: Steven A. Falco <sfalco@harris.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi/spi_ppc4xx.c')
-rw-r--r--drivers/spi/spi_ppc4xx.c612
1 files changed, 612 insertions, 0 deletions
diff --git a/drivers/spi/spi_ppc4xx.c b/drivers/spi/spi_ppc4xx.c
new file mode 100644
index 000000000000..140a18d6cf3e
--- /dev/null
+++ b/drivers/spi/spi_ppc4xx.c
@@ -0,0 +1,612 @@
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/errno.h>
30#include <linux/wait.h>
31#include <linux/of_platform.h>
32#include <linux/of_spi.h>
33#include <linux/of_gpio.h>
34#include <linux/interrupt.h>
35#include <linux/delay.h>
36
37#include <linux/gpio.h>
38#include <linux/spi/spi.h>
39#include <linux/spi/spi_bitbang.h>
40
41#include <asm/io.h>
42#include <asm/dcr.h>
43#include <asm/dcr-regs.h>
44
45/* bits in mode register - bit 0 is MSb */
46
47/*
48 * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock"
49 * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock"
50 * Note: This is the inverse of CPHA.
51 */
52#define SPI_PPC4XX_MODE_SCP (0x80 >> 3)
53
54/* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */
55#define SPI_PPC4XX_MODE_SPE (0x80 >> 4)
56
57/*
58 * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode
59 * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode
60 * Note: This is identical to SPI_LSB_FIRST.
61 */
62#define SPI_PPC4XX_MODE_RD (0x80 >> 5)
63
64/*
65 * SPI_PPC4XX_MODE_CI = 0 means "clock idles low"
66 * SPI_PPC4XX_MODE_CI = 1 means "clock idles high"
67 * Note: This is identical to CPOL.
68 */
69#define SPI_PPC4XX_MODE_CI (0x80 >> 6)
70
71/*
72 * SPI_PPC4XX_MODE_IL = 0 means "loopback disable"
73 * SPI_PPC4XX_MODE_IL = 1 means "loopback enable"
74 */
75#define SPI_PPC4XX_MODE_IL (0x80 >> 7)
76
77/* bits in control register */
78/* starts a transfer when set */
79#define SPI_PPC4XX_CR_STR (0x80 >> 7)
80
81/* bits in status register */
82/* port is busy with a transfer */
83#define SPI_PPC4XX_SR_BSY (0x80 >> 6)
84/* RxD ready */
85#define SPI_PPC4XX_SR_RBR (0x80 >> 7)
86
87/* clock settings (SCP and CI) for various SPI modes */
88#define SPI_CLK_MODE0 (SPI_PPC4XX_MODE_SCP | 0)
89#define SPI_CLK_MODE1 (0 | 0)
90#define SPI_CLK_MODE2 (SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI)
91#define SPI_CLK_MODE3 (0 | SPI_PPC4XX_MODE_CI)
92
93#define DRIVER_NAME "spi_ppc4xx_of"
94
95struct spi_ppc4xx_regs {
96 u8 mode;
97 u8 rxd;
98 u8 txd;
99 u8 cr;
100 u8 sr;
101 u8 dummy;
102 /*
103 * Clock divisor modulus register
104 * This uses the follwing formula:
105 * SCPClkOut = OPBCLK/(4(CDM + 1))
106 * or
107 * CDM = (OPBCLK/4*SCPClkOut) - 1
108 * bit 0 is the MSb!
109 */
110 u8 cdm;
111};
112
113/* SPI Controller driver's private data. */
114struct ppc4xx_spi {
115 /* bitbang has to be first */
116 struct spi_bitbang bitbang;
117 struct completion done;
118
119 u64 mapbase;
120 u64 mapsize;
121 int irqnum;
122 /* need this to set the SPI clock */
123 unsigned int opb_freq;
124
125 /* for transfers */
126 int len;
127 int count;
128 /* data buffers */
129 const unsigned char *tx;
130 unsigned char *rx;
131
132 int *gpios;
133
134 struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */
135 struct spi_master *master;
136 struct device *dev;
137};
138
139/* need this so we can set the clock in the chipselect routine */
140struct spi_ppc4xx_cs {
141 u8 mode;
142};
143
144static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t)
145{
146 struct ppc4xx_spi *hw;
147 u8 data;
148
149 dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
150 t->tx_buf, t->rx_buf, t->len);
151
152 hw = spi_master_get_devdata(spi->master);
153
154 hw->tx = t->tx_buf;
155 hw->rx = t->rx_buf;
156 hw->len = t->len;
157 hw->count = 0;
158
159 /* send the first byte */
160 data = hw->tx ? hw->tx[0] : 0;
161 out_8(&hw->regs->txd, data);
162 out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
163 wait_for_completion(&hw->done);
164
165 return hw->count;
166}
167
168static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
169{
170 struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
171 struct spi_ppc4xx_cs *cs = spi->controller_state;
172 int scr;
173 u8 cdm = 0;
174 u32 speed;
175 u8 bits_per_word;
176
177 /* Start with the generic configuration for this device. */
178 bits_per_word = spi->bits_per_word;
179 speed = spi->max_speed_hz;
180
181 /*
182 * Modify the configuration if the transfer overrides it. Do not allow
183 * the transfer to overwrite the generic configuration with zeros.
184 */
185 if (t) {
186 if (t->bits_per_word)
187 bits_per_word = t->bits_per_word;
188
189 if (t->speed_hz)
190 speed = min(t->speed_hz, spi->max_speed_hz);
191 }
192
193 if (bits_per_word != 8) {
194 dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
195 bits_per_word);
196 return -EINVAL;
197 }
198
199 if (!speed || (speed > spi->max_speed_hz)) {
200 dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
201 return -EINVAL;
202 }
203
204 /* Write new configration */
205 out_8(&hw->regs->mode, cs->mode);
206
207 /* Set the clock */
208 /* opb_freq was already divided by 4 */
209 scr = (hw->opb_freq / speed) - 1;
210 if (scr > 0)
211 cdm = min(scr, 0xff);
212
213 dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
214
215 if (in_8(&hw->regs->cdm) != cdm)
216 out_8(&hw->regs->cdm, cdm);
217
218 spin_lock(&hw->bitbang.lock);
219 if (!hw->bitbang.busy) {
220 hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
221 /* Need to ndelay here? */
222 }
223 spin_unlock(&hw->bitbang.lock);
224
225 return 0;
226}
227
228static int spi_ppc4xx_setup(struct spi_device *spi)
229{
230 struct spi_ppc4xx_cs *cs = spi->controller_state;
231
232 if (spi->bits_per_word != 8) {
233 dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
234 spi->bits_per_word);
235 return -EINVAL;
236 }
237
238 if (!spi->max_speed_hz) {
239 dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
240 return -EINVAL;
241 }
242
243 if (cs == NULL) {
244 cs = kzalloc(sizeof *cs, GFP_KERNEL);
245 if (!cs)
246 return -ENOMEM;
247 spi->controller_state = cs;
248 }
249
250 /*
251 * We set all bits of the SPI0_MODE register, so,
252 * no need to read-modify-write
253 */
254 cs->mode = SPI_PPC4XX_MODE_SPE;
255
256 switch (spi->mode & (SPI_CPHA | SPI_CPOL)) {
257 case SPI_MODE_0:
258 cs->mode |= SPI_CLK_MODE0;
259 break;
260 case SPI_MODE_1:
261 cs->mode |= SPI_CLK_MODE1;
262 break;
263 case SPI_MODE_2:
264 cs->mode |= SPI_CLK_MODE2;
265 break;
266 case SPI_MODE_3:
267 cs->mode |= SPI_CLK_MODE3;
268 break;
269 }
270
271 if (spi->mode & SPI_LSB_FIRST)
272 cs->mode |= SPI_PPC4XX_MODE_RD;
273
274 return 0;
275}
276
277static void spi_ppc4xx_chipsel(struct spi_device *spi, int value)
278{
279 struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
280 unsigned int cs = spi->chip_select;
281 unsigned int cspol;
282
283 /*
284 * If there are no chip selects at all, or if this is the special
285 * case of a non-existent (dummy) chip select, do nothing.
286 */
287
288 if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST)
289 return;
290
291 cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
292 if (value == BITBANG_CS_INACTIVE)
293 cspol = !cspol;
294
295 gpio_set_value(hw->gpios[cs], cspol);
296}
297
298static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
299{
300 struct ppc4xx_spi *hw;
301 u8 status;
302 u8 data;
303 unsigned int count;
304
305 hw = (struct ppc4xx_spi *)dev_id;
306
307 status = in_8(&hw->regs->sr);
308 if (!status)
309 return IRQ_NONE;
310
311 /*
312 * BSY de-asserts one cycle after the transfer is complete. The
313 * interrupt is asserted after the transfer is complete. The exact
314 * relationship is not documented, hence this code.
315 */
316
317 if (unlikely(status & SPI_PPC4XX_SR_BSY)) {
318 u8 lstatus;
319 int cnt = 0;
320
321 dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
322 do {
323 ndelay(10);
324 lstatus = in_8(&hw->regs->sr);
325 } while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
326
327 if (cnt >= 100) {
328 dev_err(hw->dev, "busywait: too many loops!\n");
329 complete(&hw->done);
330 return IRQ_HANDLED;
331 } else {
332 /* status is always 1 (RBR) here */
333 status = in_8(&hw->regs->sr);
334 dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
335 }
336 }
337
338 count = hw->count;
339 hw->count++;
340
341 /* RBR triggered this interrupt. Therefore, data must be ready. */
342 data = in_8(&hw->regs->rxd);
343 if (hw->rx)
344 hw->rx[count] = data;
345
346 count++;
347
348 if (count < hw->len) {
349 data = hw->tx ? hw->tx[count] : 0;
350 out_8(&hw->regs->txd, data);
351 out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
352 } else {
353 complete(&hw->done);
354 }
355
356 return IRQ_HANDLED;
357}
358
359static void spi_ppc4xx_cleanup(struct spi_device *spi)
360{
361 kfree(spi->controller_state);
362}
363
364static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
365{
366 /*
367 * On all 4xx PPC's the SPI bus is shared/multiplexed with
368 * the 2nd I2C bus. We need to enable the the SPI bus before
369 * using it.
370 */
371
372 /* need to clear bit 14 to enable SPC */
373 dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
374}
375
376static void free_gpios(struct ppc4xx_spi *hw)
377{
378 if (hw->master->num_chipselect) {
379 int i;
380 for (i = 0; i < hw->master->num_chipselect; i++)
381 if (gpio_is_valid(hw->gpios[i]))
382 gpio_free(hw->gpios[i]);
383
384 kfree(hw->gpios);
385 hw->gpios = NULL;
386 }
387}
388
389/*
390 * of_device layer stuff...
391 */
392static int __init spi_ppc4xx_of_probe(struct of_device *op,
393 const struct of_device_id *match)
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->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 dev_set_drvdata(dev, master);
410 hw = spi_master_get_devdata(master);
411 hw->master = spi_master_get(master);
412 hw->dev = dev;
413
414 init_completion(&hw->done);
415
416 /*
417 * A count of zero implies a single SPI device without any chip-select.
418 * Note that of_gpio_count counts all gpios assigned to this spi master.
419 * This includes both "null" gpio's and real ones.
420 */
421 num_gpios = of_gpio_count(np);
422 if (num_gpios) {
423 int i;
424
425 hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL);
426 if (!hw->gpios) {
427 ret = -ENOMEM;
428 goto free_master;
429 }
430
431 for (i = 0; i < num_gpios; i++) {
432 int gpio;
433 enum of_gpio_flags flags;
434
435 gpio = of_get_gpio_flags(np, i, &flags);
436 hw->gpios[i] = gpio;
437
438 if (gpio_is_valid(gpio)) {
439 /* Real CS - set the initial state. */
440 ret = gpio_request(gpio, np->name);
441 if (ret < 0) {
442 dev_err(dev, "can't request gpio "
443 "#%d: %d\n", i, ret);
444 goto free_gpios;
445 }
446
447 gpio_direction_output(gpio,
448 !!(flags & OF_GPIO_ACTIVE_LOW));
449 } else if (gpio == -EEXIST) {
450 ; /* No CS, but that's OK. */
451 } else {
452 dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
453 ret = -EINVAL;
454 goto free_gpios;
455 }
456 }
457 }
458
459 /* Setup the state for the bitbang driver */
460 bbp = &hw->bitbang;
461 bbp->master = hw->master;
462 bbp->setup_transfer = spi_ppc4xx_setupxfer;
463 bbp->chipselect = spi_ppc4xx_chipsel;
464 bbp->txrx_bufs = spi_ppc4xx_txrx;
465 bbp->use_dma = 0;
466 bbp->master->setup = spi_ppc4xx_setup;
467 bbp->master->cleanup = spi_ppc4xx_cleanup;
468
469 /* Allocate bus num dynamically. */
470 bbp->master->bus_num = -1;
471
472 /* the spi->mode bits understood by this driver: */
473 bbp->master->mode_bits =
474 SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST;
475
476 /* this many pins in all GPIO controllers */
477 bbp->master->num_chipselect = num_gpios;
478
479 /* Get the clock for the OPB */
480 opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
481 if (opbnp == NULL) {
482 dev_err(dev, "OPB: cannot find node\n");
483 ret = -ENODEV;
484 goto free_gpios;
485 }
486 /* Get the clock (Hz) for the OPB */
487 clk = of_get_property(opbnp, "clock-frequency", NULL);
488 if (clk == NULL) {
489 dev_err(dev, "OPB: no clock-frequency property set\n");
490 of_node_put(opbnp);
491 ret = -ENODEV;
492 goto free_gpios;
493 }
494 hw->opb_freq = *clk;
495 hw->opb_freq >>= 2;
496 of_node_put(opbnp);
497
498 ret = of_address_to_resource(np, 0, &resource);
499 if (ret) {
500 dev_err(dev, "error while parsing device node resource\n");
501 goto free_gpios;
502 }
503 hw->mapbase = resource.start;
504 hw->mapsize = resource.end - resource.start + 1;
505
506 /* Sanity check */
507 if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
508 dev_err(dev, "too small to map registers\n");
509 ret = -EINVAL;
510 goto free_gpios;
511 }
512
513 /* Request IRQ */
514 hw->irqnum = irq_of_parse_and_map(np, 0);
515 ret = request_irq(hw->irqnum, spi_ppc4xx_int,
516 IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw);
517 if (ret) {
518 dev_err(dev, "unable to allocate interrupt\n");
519 goto free_gpios;
520 }
521
522 if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
523 dev_err(dev, "resource unavailable\n");
524 ret = -EBUSY;
525 goto request_mem_error;
526 }
527
528 hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
529
530 if (!hw->regs) {
531 dev_err(dev, "unable to memory map registers\n");
532 ret = -ENXIO;
533 goto map_io_error;
534 }
535
536 spi_ppc4xx_enable(hw);
537
538 /* Finally register our spi controller */
539 dev->dma_mask = 0;
540 ret = spi_bitbang_start(bbp);
541 if (ret) {
542 dev_err(dev, "failed to register SPI master\n");
543 goto unmap_regs;
544 }
545
546 dev_info(dev, "driver initialized\n");
547 of_register_spi_devices(master, np);
548
549 return 0;
550
551unmap_regs:
552 iounmap(hw->regs);
553map_io_error:
554 release_mem_region(hw->mapbase, hw->mapsize);
555request_mem_error:
556 free_irq(hw->irqnum, hw);
557free_gpios:
558 free_gpios(hw);
559free_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
567static int __exit spi_ppc4xx_of_remove(struct of_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
581static struct of_device_id spi_ppc4xx_of_match[] = {
582 { .compatible = "ibm,ppc4xx-spi", },
583 {},
584};
585
586MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
587
588static struct of_platform_driver spi_ppc4xx_of_driver = {
589 .match_table = spi_ppc4xx_of_match,
590 .probe = spi_ppc4xx_of_probe,
591 .remove = __exit_p(spi_ppc4xx_of_remove),
592 .driver = {
593 .name = DRIVER_NAME,
594 .owner = THIS_MODULE,
595 },
596};
597
598static int __init spi_ppc4xx_init(void)
599{
600 return of_register_platform_driver(&spi_ppc4xx_of_driver);
601}
602module_init(spi_ppc4xx_init);
603
604static void __exit spi_ppc4xx_exit(void)
605{
606 of_unregister_platform_driver(&spi_ppc4xx_of_driver);
607}
608module_exit(spi_ppc4xx_exit);
609
610MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
611MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
612MODULE_LICENSE("GPL");