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/sched.h>
28 #include <linux/slab.h>
29 #include <linux/errno.h>
30 #include <linux/wait.h>
31 #include <linux/of_address.h>
32 #include <linux/of_irq.h>
33 #include <linux/of_platform.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 following 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
spi_ppc4xx_txrx(struct spi_device * spi,struct spi_transfer * t)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
spi_ppc4xx_setupxfer(struct spi_device * spi,struct spi_transfer * t)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 (!speed || (speed > spi->max_speed_hz)) {
195 dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
196 return -EINVAL;
197 }
198
199 /* Write new configuration */
200 out_8(&hw->regs->mode, cs->mode);
201
202 /* Set the clock */
203 /* opb_freq was already divided by 4 */
204 scr = (hw->opb_freq / speed) - 1;
205 if (scr > 0)
206 cdm = min(scr, 0xff);
207
208 dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
209
210 if (in_8(&hw->regs->cdm) != cdm)
211 out_8(&hw->regs->cdm, cdm);
212
213 mutex_lock(&hw->bitbang.lock);
214 if (!hw->bitbang.busy) {
215 hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
216 /* Need to ndelay here? */
217 }
218 mutex_unlock(&hw->bitbang.lock);
219
220 return 0;
221 }
222
spi_ppc4xx_setup(struct spi_device * spi)223 static int spi_ppc4xx_setup(struct spi_device *spi)
224 {
225 struct spi_ppc4xx_cs *cs = spi->controller_state;
226
227 if (!spi->max_speed_hz) {
228 dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
229 return -EINVAL;
230 }
231
232 if (cs == NULL) {
233 cs = kzalloc(sizeof *cs, GFP_KERNEL);
234 if (!cs)
235 return -ENOMEM;
236 spi->controller_state = cs;
237 }
238
239 /*
240 * We set all bits of the SPI0_MODE register, so,
241 * no need to read-modify-write
242 */
243 cs->mode = SPI_PPC4XX_MODE_SPE;
244
245 switch (spi->mode & (SPI_CPHA | SPI_CPOL)) {
246 case SPI_MODE_0:
247 cs->mode |= SPI_CLK_MODE0;
248 break;
249 case SPI_MODE_1:
250 cs->mode |= SPI_CLK_MODE1;
251 break;
252 case SPI_MODE_2:
253 cs->mode |= SPI_CLK_MODE2;
254 break;
255 case SPI_MODE_3:
256 cs->mode |= SPI_CLK_MODE3;
257 break;
258 }
259
260 if (spi->mode & SPI_LSB_FIRST)
261 cs->mode |= SPI_PPC4XX_MODE_RD;
262
263 return 0;
264 }
265
spi_ppc4xx_chipsel(struct spi_device * spi,int value)266 static void spi_ppc4xx_chipsel(struct spi_device *spi, int value)
267 {
268 struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
269 unsigned int cs = spi->chip_select;
270 unsigned int cspol;
271
272 /*
273 * If there are no chip selects at all, or if this is the special
274 * case of a non-existent (dummy) chip select, do nothing.
275 */
276
277 if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST)
278 return;
279
280 cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
281 if (value == BITBANG_CS_INACTIVE)
282 cspol = !cspol;
283
284 gpio_set_value(hw->gpios[cs], cspol);
285 }
286
spi_ppc4xx_int(int irq,void * dev_id)287 static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
288 {
289 struct ppc4xx_spi *hw;
290 u8 status;
291 u8 data;
292 unsigned int count;
293
294 hw = (struct ppc4xx_spi *)dev_id;
295
296 status = in_8(&hw->regs->sr);
297 if (!status)
298 return IRQ_NONE;
299
300 /*
301 * BSY de-asserts one cycle after the transfer is complete. The
302 * interrupt is asserted after the transfer is complete. The exact
303 * relationship is not documented, hence this code.
304 */
305
306 if (unlikely(status & SPI_PPC4XX_SR_BSY)) {
307 u8 lstatus;
308 int cnt = 0;
309
310 dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
311 do {
312 ndelay(10);
313 lstatus = in_8(&hw->regs->sr);
314 } while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
315
316 if (cnt >= 100) {
317 dev_err(hw->dev, "busywait: too many loops!\n");
318 complete(&hw->done);
319 return IRQ_HANDLED;
320 } else {
321 /* status is always 1 (RBR) here */
322 status = in_8(&hw->regs->sr);
323 dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
324 }
325 }
326
327 count = hw->count;
328 hw->count++;
329
330 /* RBR triggered this interrupt. Therefore, data must be ready. */
331 data = in_8(&hw->regs->rxd);
332 if (hw->rx)
333 hw->rx[count] = data;
334
335 count++;
336
337 if (count < hw->len) {
338 data = hw->tx ? hw->tx[count] : 0;
339 out_8(&hw->regs->txd, data);
340 out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
341 } else {
342 complete(&hw->done);
343 }
344
345 return IRQ_HANDLED;
346 }
347
spi_ppc4xx_cleanup(struct spi_device * spi)348 static void spi_ppc4xx_cleanup(struct spi_device *spi)
349 {
350 kfree(spi->controller_state);
351 }
352
spi_ppc4xx_enable(struct ppc4xx_spi * hw)353 static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
354 {
355 /*
356 * On all 4xx PPC's the SPI bus is shared/multiplexed with
357 * the 2nd I2C bus. We need to enable the the SPI bus before
358 * using it.
359 */
360
361 /* need to clear bit 14 to enable SPC */
362 dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
363 }
364
free_gpios(struct ppc4xx_spi * hw)365 static void free_gpios(struct ppc4xx_spi *hw)
366 {
367 if (hw->master->num_chipselect) {
368 int i;
369 for (i = 0; i < hw->master->num_chipselect; i++)
370 if (gpio_is_valid(hw->gpios[i]))
371 gpio_free(hw->gpios[i]);
372
373 kfree(hw->gpios);
374 hw->gpios = NULL;
375 }
376 }
377
378 /*
379 * platform_device layer stuff...
380 */
spi_ppc4xx_of_probe(struct platform_device * op)381 static int spi_ppc4xx_of_probe(struct platform_device *op)
382 {
383 struct ppc4xx_spi *hw;
384 struct spi_master *master;
385 struct spi_bitbang *bbp;
386 struct resource resource;
387 struct device_node *np = op->dev.of_node;
388 struct device *dev = &op->dev;
389 struct device_node *opbnp;
390 int ret;
391 int num_gpios;
392 const unsigned int *clk;
393
394 master = spi_alloc_master(dev, sizeof *hw);
395 if (master == NULL)
396 return -ENOMEM;
397 master->dev.of_node = np;
398 platform_set_drvdata(op, master);
399 hw = spi_master_get_devdata(master);
400 hw->master = master;
401 hw->dev = dev;
402
403 init_completion(&hw->done);
404
405 /*
406 * A count of zero implies a single SPI device without any chip-select.
407 * Note that of_gpio_count counts all gpios assigned to this spi master.
408 * This includes both "null" gpio's and real ones.
409 */
410 num_gpios = of_gpio_count(np);
411 if (num_gpios > 0) {
412 int i;
413
414 hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL);
415 if (!hw->gpios) {
416 ret = -ENOMEM;
417 goto free_master;
418 }
419
420 for (i = 0; i < num_gpios; i++) {
421 int gpio;
422 enum of_gpio_flags flags;
423
424 gpio = of_get_gpio_flags(np, i, &flags);
425 hw->gpios[i] = gpio;
426
427 if (gpio_is_valid(gpio)) {
428 /* Real CS - set the initial state. */
429 ret = gpio_request(gpio, np->name);
430 if (ret < 0) {
431 dev_err(dev, "can't request gpio "
432 "#%d: %d\n", i, ret);
433 goto free_gpios;
434 }
435
436 gpio_direction_output(gpio,
437 !!(flags & OF_GPIO_ACTIVE_LOW));
438 } else if (gpio == -EEXIST) {
439 ; /* No CS, but that's OK. */
440 } else {
441 dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
442 ret = -EINVAL;
443 goto free_gpios;
444 }
445 }
446 }
447
448 /* Setup the state for the bitbang driver */
449 bbp = &hw->bitbang;
450 bbp->master = hw->master;
451 bbp->setup_transfer = spi_ppc4xx_setupxfer;
452 bbp->chipselect = spi_ppc4xx_chipsel;
453 bbp->txrx_bufs = spi_ppc4xx_txrx;
454 bbp->use_dma = 0;
455 bbp->master->setup = spi_ppc4xx_setup;
456 bbp->master->cleanup = spi_ppc4xx_cleanup;
457 bbp->master->bits_per_word_mask = SPI_BPW_MASK(8);
458
459 /* the spi->mode bits understood by this driver: */
460 bbp->master->mode_bits =
461 SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST;
462
463 /* this many pins in all GPIO controllers */
464 bbp->master->num_chipselect = num_gpios > 0 ? num_gpios : 0;
465
466 /* Get the clock for the OPB */
467 opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
468 if (opbnp == NULL) {
469 dev_err(dev, "OPB: cannot find node\n");
470 ret = -ENODEV;
471 goto free_gpios;
472 }
473 /* Get the clock (Hz) for the OPB */
474 clk = of_get_property(opbnp, "clock-frequency", NULL);
475 if (clk == NULL) {
476 dev_err(dev, "OPB: no clock-frequency property set\n");
477 of_node_put(opbnp);
478 ret = -ENODEV;
479 goto free_gpios;
480 }
481 hw->opb_freq = *clk;
482 hw->opb_freq >>= 2;
483 of_node_put(opbnp);
484
485 ret = of_address_to_resource(np, 0, &resource);
486 if (ret) {
487 dev_err(dev, "error while parsing device node resource\n");
488 goto free_gpios;
489 }
490 hw->mapbase = resource.start;
491 hw->mapsize = resource_size(&resource);
492
493 /* Sanity check */
494 if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
495 dev_err(dev, "too small to map registers\n");
496 ret = -EINVAL;
497 goto free_gpios;
498 }
499
500 /* Request IRQ */
501 hw->irqnum = irq_of_parse_and_map(np, 0);
502 ret = request_irq(hw->irqnum, spi_ppc4xx_int,
503 0, "spi_ppc4xx_of", (void *)hw);
504 if (ret) {
505 dev_err(dev, "unable to allocate interrupt\n");
506 goto free_gpios;
507 }
508
509 if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
510 dev_err(dev, "resource unavailable\n");
511 ret = -EBUSY;
512 goto request_mem_error;
513 }
514
515 hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
516
517 if (!hw->regs) {
518 dev_err(dev, "unable to memory map registers\n");
519 ret = -ENXIO;
520 goto map_io_error;
521 }
522
523 spi_ppc4xx_enable(hw);
524
525 /* Finally register our spi controller */
526 dev->dma_mask = 0;
527 ret = spi_bitbang_start(bbp);
528 if (ret) {
529 dev_err(dev, "failed to register SPI master\n");
530 goto unmap_regs;
531 }
532
533 dev_info(dev, "driver initialized\n");
534
535 return 0;
536
537 unmap_regs:
538 iounmap(hw->regs);
539 map_io_error:
540 release_mem_region(hw->mapbase, hw->mapsize);
541 request_mem_error:
542 free_irq(hw->irqnum, hw);
543 free_gpios:
544 free_gpios(hw);
545 free_master:
546 spi_master_put(master);
547
548 dev_err(dev, "initialization failed\n");
549 return ret;
550 }
551
spi_ppc4xx_of_remove(struct platform_device * op)552 static int spi_ppc4xx_of_remove(struct platform_device *op)
553 {
554 struct spi_master *master = platform_get_drvdata(op);
555 struct ppc4xx_spi *hw = spi_master_get_devdata(master);
556
557 spi_bitbang_stop(&hw->bitbang);
558 release_mem_region(hw->mapbase, hw->mapsize);
559 free_irq(hw->irqnum, hw);
560 iounmap(hw->regs);
561 free_gpios(hw);
562 spi_master_put(master);
563 return 0;
564 }
565
566 static const struct of_device_id spi_ppc4xx_of_match[] = {
567 { .compatible = "ibm,ppc4xx-spi", },
568 {},
569 };
570
571 MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
572
573 static struct platform_driver spi_ppc4xx_of_driver = {
574 .probe = spi_ppc4xx_of_probe,
575 .remove = spi_ppc4xx_of_remove,
576 .driver = {
577 .name = DRIVER_NAME,
578 .of_match_table = spi_ppc4xx_of_match,
579 },
580 };
581 module_platform_driver(spi_ppc4xx_of_driver);
582
583 MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
584 MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
585 MODULE_LICENSE("GPL");
586