summaryrefslogtreecommitdiffstats
path: root/drivers/spi/spi_s3c24xx.c
blob: 1c643c9e1f15ff793e5d7c140e9f93ee96320544 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
/* linux/drivers/spi/spi_s3c24xx.c
 *
 * Copyright (c) 2006 Ben Dooks
 * Copyright (c) 2006 Simtec Electronics
 *	Ben Dooks <ben@simtec.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
*/

#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/platform_device.h>

#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>

#include <asm/io.h>
#include <asm/dma.h>
#include <asm/hardware.h>

#include <asm/arch/regs-gpio.h>
#include <asm/plat-s3c24xx/regs-spi.h>
#include <asm/arch/spi.h>

struct s3c24xx_spi {
	/* bitbang has to be first */
	struct spi_bitbang	 bitbang;
	struct completion	 done;

	void __iomem		*regs;
	int			 irq;
	int			 len;
	int			 count;

	void			(*set_cs)(struct s3c2410_spi_info *spi,
					  int cs, int pol);

	/* data buffers */
	const unsigned char	*tx;
	unsigned char		*rx;

	struct clk		*clk;
	struct resource		*ioarea;
	struct spi_master	*master;
	struct spi_device	*curdev;
	struct device		*dev;
	struct s3c2410_spi_info *pdata;
};

#define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT)
#define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)

static inline struct s3c24xx_spi *to_hw(struct spi_device *sdev)
{
	return spi_master_get_devdata(sdev->master);
}

static void s3c24xx_spi_gpiocs(struct s3c2410_spi_info *spi, int cs, int pol)
{
	s3c2410_gpio_setpin(spi->pin_cs, pol);
}

static void s3c24xx_spi_chipsel(struct spi_device *spi, int value)
{
	struct s3c24xx_spi *hw = to_hw(spi);
	unsigned int cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
	unsigned int spcon;

	switch (value) {
	case BITBANG_CS_INACTIVE:
		hw->set_cs(hw->pdata, spi->chip_select, cspol^1);
		break;

	case BITBANG_CS_ACTIVE:
		spcon = readb(hw->regs + S3C2410_SPCON);

		if (spi->mode & SPI_CPHA)
			spcon |= S3C2410_SPCON_CPHA_FMTB;
		else
			spcon &= ~S3C2410_SPCON_CPHA_FMTB;

		if (spi->mode & SPI_CPOL)
			spcon |= S3C2410_SPCON_CPOL_HIGH;
		else
			spcon &= ~S3C2410_SPCON_CPOL_HIGH;

		spcon |= S3C2410_SPCON_ENSCK;

		/* write new configration */

		writeb(spcon, hw->regs + S3C2410_SPCON);
		hw->set_cs(hw->pdata, spi->chip_select, cspol);

		break;
	}
}

static int s3c24xx_spi_setupxfer(struct spi_device *spi,
				 struct spi_transfer *t)
{
	struct s3c24xx_spi *hw = to_hw(spi);
	unsigned int bpw;
	unsigned int hz;
	unsigned int div;

	bpw = t ? t->bits_per_word : spi->bits_per_word;
	hz  = t ? t->speed_hz : spi->max_speed_hz;

	if (bpw != 8) {
		dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bpw);
		return -EINVAL;
	}

	div = clk_get_rate(hw->clk) / hz;

	/* is clk = pclk / (2 * (pre+1)), or is it
	 *    clk = (pclk * 2) / ( pre + 1) */

	div /= 2;

	if (div > 0)
		div -= 1;

	if (div > 255)
		div = 255;

	dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", div, hz);
	writeb(div, hw->regs + S3C2410_SPPRE);

	spin_lock(&hw->bitbang.lock);
	if (!hw->bitbang.busy) {
		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
		/* need to ndelay for 0.5 clocktick ? */
	}
	spin_unlock(&hw->bitbang.lock);

	return 0;
}

/* the spi->mode bits understood by this driver: */
#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)

static int s3c24xx_spi_setup(struct spi_device *spi)
{
	int ret;

	if (!spi->bits_per_word)
		spi->bits_per_word = 8;

	if (spi->mode & ~MODEBITS) {
		dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
			spi->mode & ~MODEBITS);
		return -EINVAL;
	}

	ret = s3c24xx_spi_setupxfer(spi, NULL);
	if (ret < 0) {
		dev_err(&spi->dev, "setupxfer returned %d\n", ret);
		return ret;
	}

	dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
		__func__, spi->mode, spi->bits_per_word,
		spi->max_speed_hz);

	return 0;
}

static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
{
	return hw->tx ? hw->tx[count] : 0;
}

static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
{
	struct s3c24xx_spi *hw = to_hw(spi);

	dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
		t->tx_buf, t->rx_buf, t->len);

	hw->tx = t->tx_buf;
	hw->rx = t->rx_buf;
	hw->len = t->len;
	hw->count = 0;

	init_completion(&hw->done);

	/* send the first byte */
	writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);

	wait_for_completion(&hw->done);

	return hw->count;
}

static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
{
	struct s3c24xx_spi *hw = dev;
	unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
	unsigned int count = hw->count;

	if (spsta & S3C2410_SPSTA_DCOL) {
		dev_dbg(hw->dev, "data-collision\n");
		complete(&hw->done);
		goto irq_done;
	}

	if (!(spsta & S3C2410_SPSTA_READY)) {
		dev_dbg(hw->dev, "spi not ready for tx?\n");
		complete(&hw->done);
		goto irq_done;
	}

	hw->count++;

	if (hw->rx)
		hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);

	count++;

	if (count < hw->len)
		writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
	else
		complete(&hw->done);

 irq_done:
	return IRQ_HANDLED;
}

static int __init s3c24xx_spi_probe(struct platform_device *pdev)
{
	struct s3c2410_spi_info *pdata;
	struct s3c24xx_spi *hw;
	struct spi_master *master;
	struct resource *res;
	int err = 0;

	master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi));
	if (master == NULL) {
		dev_err(&pdev->dev, "No memory for spi_master\n");
		err = -ENOMEM;
		goto err_nomem;
	}

	hw = spi_master_get_devdata(master);
	memset(hw, 0, sizeof(struct s3c24xx_spi));

	hw->master = spi_master_get(master);
	hw->pdata = pdata = pdev->dev.platform_data;
	hw->dev = &pdev->dev;

	if (pdata == NULL) {
		dev_err(&pdev->dev, "No platform data supplied\n");
		err = -ENOENT;
		goto err_no_pdata;
	}

	platform_set_drvdata(pdev, hw);
	init_completion(&hw->done);

	/* setup the master state. */

	master->num_chipselect = hw->pdata->num_cs;
	master->bus_num = pdata->bus_num;

	/* setup the state for the bitbang driver */

	hw->bitbang.master         = hw->master;
	hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
	hw->bitbang.chipselect     = s3c24xx_spi_chipsel;
	hw->bitbang.txrx_bufs      = s3c24xx_spi_txrx;
	hw->bitbang.master->setup  = s3c24xx_spi_setup;

	dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);

	/* find and map our resources */

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
		err = -ENOENT;
		goto err_no_iores;
	}

	hw->ioarea = request_mem_region(res->start, (res->end - res->start)+1,
					pdev->name);

	if (hw->ioarea == NULL) {
		dev_err(&pdev->dev, "Cannot reserve region\n");
		err = -ENXIO;
		goto err_no_iores;
	}

	hw->regs = ioremap(res->start, (res->end - res->start)+1);
	if (hw->regs == NULL) {
		dev_err(&pdev->dev, "Cannot map IO\n");
		err = -ENXIO;
		goto err_no_iomap;
	}

	hw->irq = platform_get_irq(pdev, 0);
	if (hw->irq < 0) {
		dev_err(&pdev->dev, "No IRQ specified\n");
		err = -ENOENT;
		goto err_no_irq;
	}

	err = request_irq(hw->irq, s3c24xx_spi_irq, 0, pdev->name, hw);
	if (err) {
		dev_err(&pdev->dev, "Cannot claim IRQ\n");
		goto err_no_irq;
	}

	hw->clk = clk_get(&pdev->dev, "spi");
	if (IS_ERR(hw->clk)) {
		dev_err(&pdev->dev, "No clock for device\n");
		err = PTR_ERR(hw->clk);
		goto err_no_clk;
	}

	/* for the moment, permanently enable the clock */

	clk_enable(hw->clk);

	/* program defaults into the registers */

	writeb(0xff, hw->regs + S3C2410_SPPRE);
	writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
	writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);

	/* setup any gpio we can */

	if (!pdata->set_cs) {
		hw->set_cs = s3c24xx_spi_gpiocs;

		s3c2410_gpio_setpin(pdata->pin_cs, 1);
		s3c2410_gpio_cfgpin(pdata->pin_cs, S3C2410_GPIO_OUTPUT);
	} else
		hw->set_cs = pdata->set_cs;

	/* register our spi controller */

	err = spi_bitbang_start(&hw->bitbang);
	if (err) {
		dev_err(&pdev->dev, "Failed to register SPI master\n");
		goto err_register;
	}

	return 0;

 err_register:
	clk_disable(hw->clk);
	clk_put(hw->clk);

 err_no_clk:
	free_irq(hw->irq, hw);

 err_no_irq:
	iounmap(hw->regs);

 err_no_iomap:
	release_resource(hw->ioarea);
	kfree(hw->ioarea);

 err_no_iores:
 err_no_pdata:
	spi_master_put(hw->master);;

 err_nomem:
	return err;
}

static int __exit s3c24xx_spi_remove(struct platform_device *dev)
{
	struct s3c24xx_spi *hw = platform_get_drvdata(dev);

	platform_set_drvdata(dev, NULL);

	spi_unregister_master(hw->master);

	clk_disable(hw->clk);
	clk_put(hw->clk);

	free_irq(hw->irq, hw);
	iounmap(hw->regs);

	release_resource(hw->ioarea);
	kfree(hw->ioarea);

	spi_master_put(hw->master);
	return 0;
}


#ifdef CONFIG_PM

static int s3c24xx_spi_suspend(struct platform_device *pdev, pm_message_t msg)
{
	struct s3c24xx_spi *hw = platform_get_drvdata(pdev);

	clk_disable(hw->clk);
	return 0;
}

static int s3c24xx_spi_resume(struct platform_device *pdev)
{
	struct s3c24xx_spi *hw = platform_get_drvdata(pdev);

	clk_enable(hw->clk);
	return 0;
}

#else
#define s3c24xx_spi_suspend NULL
#define s3c24xx_spi_resume  NULL
#endif

MODULE_ALIAS("platform:s3c2410-spi");
static struct platform_driver s3c24xx_spidrv = {
	.remove		= __exit_p(s3c24xx_spi_remove),
	.suspend	= s3c24xx_spi_suspend,
	.resume		= s3c24xx_spi_resume,
	.driver		= {
		.name	= "s3c2410-spi",
		.owner	= THIS_MODULE,
	},
};

static int __init s3c24xx_spi_init(void)
{
        return platform_driver_probe(&s3c24xx_spidrv, s3c24xx_spi_probe);
}

static void __exit s3c24xx_spi_exit(void)
{
        platform_driver_unregister(&s3c24xx_spidrv);
}

module_init(s3c24xx_spi_init);
module_exit(s3c24xx_spi_exit);

MODULE_DESCRIPTION("S3C24XX SPI Driver");
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud