i2c-au1550.c revision f09f71b24e77a2f2b4e5c98311c8804fc61ad8bc 
1/*
2 * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
3 * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
4 *
5 * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
6 *
7 * The documentation describes this as an SMBus controller, but it doesn't
8 * understand any of the SMBus protocol in hardware.  It's really an I2C
9 * controller that could emulate most of the SMBus in software.
10 *
11 * This is just a skeleton adapter to use with the Au1550 PSC
12 * algorithm.  It was developed for the Pb1550, but will work with
13 * any Au1550 board that has a similar PSC configuration.
14 *
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * as published by the Free Software Foundation; either version 2
18 * of the License, or (at your option) any later version.
19 *
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
23 * GNU General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software
27 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
28 */
29
30#include <linux/delay.h>
31#include <linux/kernel.h>
32#include <linux/module.h>
33#include <linux/platform_device.h>
34#include <linux/init.h>
35#include <linux/errno.h>
36#include <linux/i2c.h>
37#include <linux/slab.h>
38
39#include <asm/mach-au1x00/au1xxx.h>
40#include <asm/mach-au1x00/au1xxx_psc.h>
41
42struct i2c_au1550_data {
43	u32	psc_base;
44	int	xfer_timeout;
45	int	ack_timeout;
46	struct i2c_adapter adap;
47	struct resource *ioarea;
48};
49
50static int
51wait_xfer_done(struct i2c_au1550_data *adap)
52{
53	u32	stat;
54	int	i;
55	volatile psc_smb_t	*sp;
56
57	sp = (volatile psc_smb_t *)(adap->psc_base);
58
59	/* Wait for Tx Buffer Empty
60	*/
61	for (i = 0; i < adap->xfer_timeout; i++) {
62		stat = sp->psc_smbstat;
63		au_sync();
64		if ((stat & PSC_SMBSTAT_TE) != 0)
65			return 0;
66
67		udelay(1);
68	}
69
70	return -ETIMEDOUT;
71}
72
73static int
74wait_ack(struct i2c_au1550_data *adap)
75{
76	u32	stat;
77	volatile psc_smb_t	*sp;
78
79	if (wait_xfer_done(adap))
80		return -ETIMEDOUT;
81
82	sp = (volatile psc_smb_t *)(adap->psc_base);
83
84	stat = sp->psc_smbevnt;
85	au_sync();
86
87	if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
88		return -ETIMEDOUT;
89
90	return 0;
91}
92
93static int
94wait_master_done(struct i2c_au1550_data *adap)
95{
96	u32	stat;
97	int	i;
98	volatile psc_smb_t	*sp;
99
100	sp = (volatile psc_smb_t *)(adap->psc_base);
101
102	/* Wait for Master Done.
103	*/
104	for (i = 0; i < adap->xfer_timeout; i++) {
105		stat = sp->psc_smbevnt;
106		au_sync();
107		if ((stat & PSC_SMBEVNT_MD) != 0)
108			return 0;
109		udelay(1);
110	}
111
112	return -ETIMEDOUT;
113}
114
115static int
116do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
117{
118	volatile psc_smb_t	*sp;
119	u32			stat;
120
121	sp = (volatile psc_smb_t *)(adap->psc_base);
122
123	/* Reset the FIFOs, clear events.
124	*/
125	stat = sp->psc_smbstat;
126	sp->psc_smbevnt = PSC_SMBEVNT_ALLCLR;
127	au_sync();
128
129	if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
130		sp->psc_smbpcr = PSC_SMBPCR_DC;
131		au_sync();
132		do {
133			stat = sp->psc_smbpcr;
134			au_sync();
135		} while ((stat & PSC_SMBPCR_DC) != 0);
136		udelay(50);
137	}
138
139	/* Write out the i2c chip address and specify operation
140	*/
141	addr <<= 1;
142	if (rd)
143		addr |= 1;
144
145	/* zero-byte xfers stop immediately */
146	if (q)
147		addr |= PSC_SMBTXRX_STP;
148
149	/* Put byte into fifo, start up master.
150	*/
151	sp->psc_smbtxrx = addr;
152	au_sync();
153	sp->psc_smbpcr = PSC_SMBPCR_MS;
154	au_sync();
155	if (wait_ack(adap))
156		return -EIO;
157	return (q) ? wait_master_done(adap) : 0;
158}
159
160static u32
161wait_for_rx_byte(struct i2c_au1550_data *adap, u32 *ret_data)
162{
163	int	j;
164	u32	data, stat;
165	volatile psc_smb_t	*sp;
166
167	if (wait_xfer_done(adap))
168		return -EIO;
169
170	sp = (volatile psc_smb_t *)(adap->psc_base);
171
172	j =  adap->xfer_timeout * 100;
173	do {
174		j--;
175		if (j <= 0)
176			return -EIO;
177
178		stat = sp->psc_smbstat;
179		au_sync();
180		if ((stat & PSC_SMBSTAT_RE) == 0)
181			j = 0;
182		else
183			udelay(1);
184	} while (j > 0);
185	data = sp->psc_smbtxrx;
186	au_sync();
187	*ret_data = data;
188
189	return 0;
190}
191
192static int
193i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
194		    unsigned int len)
195{
196	int	i;
197	u32	data;
198	volatile psc_smb_t	*sp;
199
200	if (len == 0)
201		return 0;
202
203	/* A read is performed by stuffing the transmit fifo with
204	 * zero bytes for timing, waiting for bytes to appear in the
205	 * receive fifo, then reading the bytes.
206	 */
207
208	sp = (volatile psc_smb_t *)(adap->psc_base);
209
210	i = 0;
211	while (i < (len-1)) {
212		sp->psc_smbtxrx = 0;
213		au_sync();
214		if (wait_for_rx_byte(adap, &data))
215			return -EIO;
216
217		buf[i] = data;
218		i++;
219	}
220
221	/* The last byte has to indicate transfer done.
222	*/
223	sp->psc_smbtxrx = PSC_SMBTXRX_STP;
224	au_sync();
225	if (wait_master_done(adap))
226		return -EIO;
227
228	data = sp->psc_smbtxrx;
229	au_sync();
230	buf[i] = data;
231	return 0;
232}
233
234static int
235i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
236		     unsigned int len)
237{
238	int	i;
239	u32	data;
240	volatile psc_smb_t	*sp;
241
242	if (len == 0)
243		return 0;
244
245	sp = (volatile psc_smb_t *)(adap->psc_base);
246
247	i = 0;
248	while (i < (len-1)) {
249		data = buf[i];
250		sp->psc_smbtxrx = data;
251		au_sync();
252		if (wait_ack(adap))
253			return -EIO;
254		i++;
255	}
256
257	/* The last byte has to indicate transfer done.
258	*/
259	data = buf[i];
260	data |= PSC_SMBTXRX_STP;
261	sp->psc_smbtxrx = data;
262	au_sync();
263	if (wait_master_done(adap))
264		return -EIO;
265	return 0;
266}
267
268static int
269au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
270{
271	struct i2c_au1550_data *adap = i2c_adap->algo_data;
272	volatile psc_smb_t *sp = (volatile psc_smb_t *)adap->psc_base;
273	struct i2c_msg *p;
274	int i, err = 0;
275
276	sp->psc_ctrl = PSC_CTRL_ENABLE;
277	au_sync();
278
279	for (i = 0; !err && i < num; i++) {
280		p = &msgs[i];
281		err = do_address(adap, p->addr, p->flags & I2C_M_RD,
282				 (p->len == 0));
283		if (err || !p->len)
284			continue;
285		if (p->flags & I2C_M_RD)
286			err = i2c_read(adap, p->buf, p->len);
287		else
288			err = i2c_write(adap, p->buf, p->len);
289	}
290
291	/* Return the number of messages processed, or the error code.
292	*/
293	if (err == 0)
294		err = num;
295
296	sp->psc_ctrl = PSC_CTRL_SUSPEND;
297	au_sync();
298
299	return err;
300}
301
302static u32
303au1550_func(struct i2c_adapter *adap)
304{
305	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
306}
307
308static const struct i2c_algorithm au1550_algo = {
309	.master_xfer	= au1550_xfer,
310	.functionality	= au1550_func,
311};
312
313static void i2c_au1550_setup(struct i2c_au1550_data *priv)
314{
315	volatile psc_smb_t *sp = (volatile psc_smb_t *)priv->psc_base;
316	u32 stat;
317
318	sp->psc_ctrl = PSC_CTRL_DISABLE;
319	au_sync();
320	sp->psc_sel = PSC_SEL_PS_SMBUSMODE;
321	sp->psc_smbcfg = 0;
322	au_sync();
323	sp->psc_ctrl = PSC_CTRL_ENABLE;
324	au_sync();
325	do {
326		stat = sp->psc_smbstat;
327		au_sync();
328	} while ((stat & PSC_SMBSTAT_SR) == 0);
329
330	sp->psc_smbcfg = (PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 |
331				PSC_SMBCFG_DD_DISABLE);
332
333	/* Divide by 8 to get a 6.25 MHz clock.  The later protocol
334	 * timings are based on this clock.
335	 */
336	sp->psc_smbcfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
337	sp->psc_smbmsk = PSC_SMBMSK_ALLMASK;
338	au_sync();
339
340	/* Set the protocol timer values.  See Table 71 in the
341	 * Au1550 Data Book for standard timing values.
342	 */
343	sp->psc_smbtmr = PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(15) | \
344		PSC_SMBTMR_SET_PU(15) | PSC_SMBTMR_SET_SH(15) | \
345		PSC_SMBTMR_SET_SU(15) | PSC_SMBTMR_SET_CL(15) | \
346		PSC_SMBTMR_SET_CH(15);
347	au_sync();
348
349	sp->psc_smbcfg |= PSC_SMBCFG_DE_ENABLE;
350	do {
351		stat = sp->psc_smbstat;
352		au_sync();
353	} while ((stat & PSC_SMBSTAT_SR) == 0);
354
355	sp->psc_ctrl = PSC_CTRL_SUSPEND;
356	au_sync();
357}
358
359static void i2c_au1550_disable(struct i2c_au1550_data *priv)
360{
361	volatile psc_smb_t *sp = (volatile psc_smb_t *)priv->psc_base;
362
363	sp->psc_smbcfg = 0;
364	sp->psc_ctrl = PSC_CTRL_DISABLE;
365	au_sync();
366}
367
368/*
369 * registering functions to load algorithms at runtime
370 * Prior to calling us, the 50MHz clock frequency and routing
371 * must have been set up for the PSC indicated by the adapter.
372 */
373static int __devinit
374i2c_au1550_probe(struct platform_device *pdev)
375{
376	struct i2c_au1550_data *priv;
377	struct resource *r;
378	int ret;
379
380	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
381	if (!r) {
382		ret = -ENODEV;
383		goto out;
384	}
385
386	priv = kzalloc(sizeof(struct i2c_au1550_data), GFP_KERNEL);
387	if (!priv) {
388		ret = -ENOMEM;
389		goto out;
390	}
391
392	priv->ioarea = request_mem_region(r->start, r->end - r->start + 1,
393					  pdev->name);
394	if (!priv->ioarea) {
395		ret = -EBUSY;
396		goto out_mem;
397	}
398
399	priv->psc_base = CKSEG1ADDR(r->start);
400	priv->xfer_timeout = 200;
401	priv->ack_timeout = 200;
402
403	priv->adap.id = I2C_HW_AU1550_PSC;
404	priv->adap.nr = pdev->id;
405	priv->adap.algo = &au1550_algo;
406	priv->adap.algo_data = priv;
407	priv->adap.dev.parent = &pdev->dev;
408	strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
409
410	/* Now, set up the PSC for SMBus PIO mode.
411	*/
412	i2c_au1550_setup(priv);
413
414	ret = i2c_add_numbered_adapter(&priv->adap);
415	if (ret == 0) {
416		platform_set_drvdata(pdev, priv);
417		return 0;
418	}
419
420	i2c_au1550_disable(priv);
421
422	release_resource(priv->ioarea);
423	kfree(priv->ioarea);
424out_mem:
425	kfree(priv);
426out:
427	return ret;
428}
429
430static int __devexit
431i2c_au1550_remove(struct platform_device *pdev)
432{
433	struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
434
435	platform_set_drvdata(pdev, NULL);
436	i2c_del_adapter(&priv->adap);
437	i2c_au1550_disable(priv);
438	release_resource(priv->ioarea);
439	kfree(priv->ioarea);
440	kfree(priv);
441	return 0;
442}
443
444#ifdef CONFIG_PM
445static int
446i2c_au1550_suspend(struct platform_device *pdev, pm_message_t state)
447{
448	struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
449
450	i2c_au1550_disable(priv);
451
452	return 0;
453}
454
455static int
456i2c_au1550_resume(struct platform_device *pdev)
457{
458	struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
459
460	i2c_au1550_setup(priv);
461
462	return 0;
463}
464#else
465#define i2c_au1550_suspend	NULL
466#define i2c_au1550_resume	NULL
467#endif
468
469static struct platform_driver au1xpsc_smbus_driver = {
470	.driver = {
471		.name	= "au1xpsc_smbus",
472		.owner	= THIS_MODULE,
473	},
474	.probe		= i2c_au1550_probe,
475	.remove		= __devexit_p(i2c_au1550_remove),
476	.suspend	= i2c_au1550_suspend,
477	.resume		= i2c_au1550_resume,
478};
479
480static int __init
481i2c_au1550_init(void)
482{
483	return platform_driver_register(&au1xpsc_smbus_driver);
484}
485
486static void __exit
487i2c_au1550_exit(void)
488{
489	platform_driver_unregister(&au1xpsc_smbus_driver);
490}
491
492MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
493MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
494MODULE_LICENSE("GPL");
495MODULE_ALIAS("platform:au1xpsc_smbus");
496
497module_init (i2c_au1550_init);
498module_exit (i2c_au1550_exit);
499