summaryrefslogtreecommitdiff
path: root/drivers/i2c/busses/i2c-au1550.c
blob: a6aae84e570656d9ef9b54bed57142c438d59211 (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
/*
 * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
 * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
 *
 * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
 *
 * The documentation describes this as an SMBus controller, but it doesn't
 * understand any of the SMBus protocol in hardware.  It's really an I2C
 * controller that could emulate most of the SMBus in software.
 *
 * This is just a skeleton adapter to use with the Au1550 PSC
 * algorithm.  It was developed for the Pb1550, but will work with
 * any Au1550 board that has a similar PSC configuration.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/slab.h>

#include <asm/mach-au1x00/au1000.h>
#include <asm/mach-au1x00/au1xxx_psc.h>

#define PSC_SEL		0x00
#define PSC_CTRL	0x04
#define PSC_SMBCFG	0x08
#define PSC_SMBMSK	0x0C
#define PSC_SMBPCR	0x10
#define PSC_SMBSTAT	0x14
#define PSC_SMBEVNT	0x18
#define PSC_SMBTXRX	0x1C
#define PSC_SMBTMR	0x20

struct i2c_au1550_data {
	void __iomem *psc_base;
	int	xfer_timeout;
	struct i2c_adapter adap;
	struct resource *ioarea;
};

static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v)
{
	__raw_writel(v, a->psc_base + r);
	wmb();
}

static inline unsigned long RD(struct i2c_au1550_data *a, int r)
{
	return __raw_readl(a->psc_base + r);
}

static int wait_xfer_done(struct i2c_au1550_data *adap)
{
	int i;

	/* Wait for Tx Buffer Empty */
	for (i = 0; i < adap->xfer_timeout; i++) {
		if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE)
			return 0;

		udelay(1);
	}

	return -ETIMEDOUT;
}

static int wait_ack(struct i2c_au1550_data *adap)
{
	unsigned long stat;

	if (wait_xfer_done(adap))
		return -ETIMEDOUT;

	stat = RD(adap, PSC_SMBEVNT);
	if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
		return -ETIMEDOUT;

	return 0;
}

static int wait_master_done(struct i2c_au1550_data *adap)
{
	int i;

	/* Wait for Master Done. */
	for (i = 0; i < 2 * adap->xfer_timeout; i++) {
		if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0)
			return 0;
		udelay(1);
	}

	return -ETIMEDOUT;
}

static int
do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
{
	unsigned long stat;

	/* Reset the FIFOs, clear events. */
	stat = RD(adap, PSC_SMBSTAT);
	WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR);

	if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
		WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC);
		while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0)
			cpu_relax();
		udelay(50);
	}

	/* Write out the i2c chip address and specify operation */
	addr <<= 1;
	if (rd)
		addr |= 1;

	/* zero-byte xfers stop immediately */
	if (q)
		addr |= PSC_SMBTXRX_STP;

	/* Put byte into fifo, start up master. */
	WR(adap, PSC_SMBTXRX, addr);
	WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS);
	if (wait_ack(adap))
		return -EIO;
	return (q) ? wait_master_done(adap) : 0;
}

static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out)
{
	int j;

	if (wait_xfer_done(adap))
		return -EIO;

	j =  adap->xfer_timeout * 100;
	do {
		j--;
		if (j <= 0)
			return -EIO;

		if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0)
			j = 0;
		else
			udelay(1);
	} while (j > 0);

	*out = RD(adap, PSC_SMBTXRX);

	return 0;
}

static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
		    unsigned int len)
{
	int i;

	if (len == 0)
		return 0;

	/* A read is performed by stuffing the transmit fifo with
	 * zero bytes for timing, waiting for bytes to appear in the
	 * receive fifo, then reading the bytes.
	 */
	i = 0;
	while (i < (len - 1)) {
		WR(adap, PSC_SMBTXRX, 0);
		if (wait_for_rx_byte(adap, &buf[i]))
			return -EIO;

		i++;
	}

	/* The last byte has to indicate transfer done. */
	WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP);
	if (wait_master_done(adap))
		return -EIO;

	buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff);
	return 0;
}

static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
		     unsigned int len)
{
	int i;
	unsigned long data;

	if (len == 0)
		return 0;

	i = 0;
	while (i < (len-1)) {
		data = buf[i];
		WR(adap, PSC_SMBTXRX, data);
		if (wait_ack(adap))
			return -EIO;
		i++;
	}

	/* The last byte has to indicate transfer done. */
	data = buf[i];
	data |= PSC_SMBTXRX_STP;
	WR(adap, PSC_SMBTXRX, data);
	if (wait_master_done(adap))
		return -EIO;
	return 0;
}

static int
au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
{
	struct i2c_au1550_data *adap = i2c_adap->algo_data;
	struct i2c_msg *p;
	int i, err = 0;

	WR(adap, PSC_CTRL, PSC_CTRL_ENABLE);

	for (i = 0; !err && i < num; i++) {
		p = &msgs[i];
		err = do_address(adap, p->addr, p->flags & I2C_M_RD,
				 (p->len == 0));
		if (err || !p->len)
			continue;
		if (p->flags & I2C_M_RD)
			err = i2c_read(adap, p->buf, p->len);
		else
			err = i2c_write(adap, p->buf, p->len);
	}

	/* Return the number of messages processed, or the error code.
	*/
	if (err == 0)
		err = num;

	WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND);

	return err;
}

static u32 au1550_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm au1550_algo = {
	.master_xfer	= au1550_xfer,
	.functionality	= au1550_func,
};

static void i2c_au1550_setup(struct i2c_au1550_data *priv)
{
	unsigned long cfg;

	WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
	WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE);
	WR(priv, PSC_SMBCFG, 0);
	WR(priv, PSC_CTRL, PSC_CTRL_ENABLE);
	while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
		cpu_relax();

	cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE;
	WR(priv, PSC_SMBCFG, cfg);

	/* Divide by 8 to get a 6.25 MHz clock.  The later protocol
	 * timings are based on this clock.
	 */
	cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
	WR(priv, PSC_SMBCFG, cfg);
	WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK);

	/* Set the protocol timer values.  See Table 71 in the
	 * Au1550 Data Book for standard timing values.
	 */
	WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(15) | \
		PSC_SMBTMR_SET_PU(15) | PSC_SMBTMR_SET_SH(15) | \
		PSC_SMBTMR_SET_SU(15) | PSC_SMBTMR_SET_CL(15) | \
		PSC_SMBTMR_SET_CH(15));

	cfg |= PSC_SMBCFG_DE_ENABLE;
	WR(priv, PSC_SMBCFG, cfg);
	while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
		cpu_relax();

	WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND);
}

static void i2c_au1550_disable(struct i2c_au1550_data *priv)
{
	WR(priv, PSC_SMBCFG, 0);
	WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
}

/*
 * registering functions to load algorithms at runtime
 * Prior to calling us, the 50MHz clock frequency and routing
 * must have been set up for the PSC indicated by the adapter.
 */
static int
i2c_au1550_probe(struct platform_device *pdev)
{
	struct i2c_au1550_data *priv;
	struct resource *r;
	int ret;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!r) {
		ret = -ENODEV;
		goto out;
	}

	priv = kzalloc(sizeof(struct i2c_au1550_data), GFP_KERNEL);
	if (!priv) {
		ret = -ENOMEM;
		goto out;
	}

	priv->ioarea = request_mem_region(r->start, resource_size(r),
					  pdev->name);
	if (!priv->ioarea) {
		ret = -EBUSY;
		goto out_mem;
	}

	priv->psc_base = ioremap(r->start, resource_size(r));
	if (!priv->psc_base) {
		ret = -EIO;
		goto out_map;
	}
	priv->xfer_timeout = 200;

	priv->adap.nr = pdev->id;
	priv->adap.algo = &au1550_algo;
	priv->adap.algo_data = priv;
	priv->adap.dev.parent = &pdev->dev;
	strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));

	/* Now, set up the PSC for SMBus PIO mode. */
	i2c_au1550_setup(priv);

	ret = i2c_add_numbered_adapter(&priv->adap);
	if (ret == 0) {
		platform_set_drvdata(pdev, priv);
		return 0;
	}

	i2c_au1550_disable(priv);
	iounmap(priv->psc_base);
out_map:
	release_resource(priv->ioarea);
	kfree(priv->ioarea);
out_mem:
	kfree(priv);
out:
	return ret;
}

static int i2c_au1550_remove(struct platform_device *pdev)
{
	struct i2c_au1550_data *priv = platform_get_drvdata(pdev);

	i2c_del_adapter(&priv->adap);
	i2c_au1550_disable(priv);
	iounmap(priv->psc_base);
	release_resource(priv->ioarea);
	kfree(priv->ioarea);
	kfree(priv);
	return 0;
}

#ifdef CONFIG_PM
static int i2c_au1550_suspend(struct device *dev)
{
	struct i2c_au1550_data *priv = dev_get_drvdata(dev);

	i2c_au1550_disable(priv);

	return 0;
}

static int i2c_au1550_resume(struct device *dev)
{
	struct i2c_au1550_data *priv = dev_get_drvdata(dev);

	i2c_au1550_setup(priv);

	return 0;
}

static const struct dev_pm_ops i2c_au1550_pmops = {
	.suspend	= i2c_au1550_suspend,
	.resume		= i2c_au1550_resume,
};

#define AU1XPSC_SMBUS_PMOPS (&i2c_au1550_pmops)

#else
#define AU1XPSC_SMBUS_PMOPS NULL
#endif

static struct platform_driver au1xpsc_smbus_driver = {
	.driver = {
		.name	= "au1xpsc_smbus",
		.pm	= AU1XPSC_SMBUS_PMOPS,
	},
	.probe		= i2c_au1550_probe,
	.remove		= i2c_au1550_remove,
};

module_platform_driver(au1xpsc_smbus_driver);

MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:au1xpsc_smbus");