saa7146_i2c.c revision 3593cab5d62c4c7abced1076710f9bc2d8847433 
1#include <media/saa7146_vv.h>
2
3static u32 saa7146_i2c_func(struct i2c_adapter *adapter)
4{
5//fm	DEB_I2C(("'%s'.\n", adapter->name));
6
7	return	  I2C_FUNC_I2C
8		| I2C_FUNC_SMBUS_QUICK
9		| I2C_FUNC_SMBUS_READ_BYTE	| I2C_FUNC_SMBUS_WRITE_BYTE
10		| I2C_FUNC_SMBUS_READ_BYTE_DATA | I2C_FUNC_SMBUS_WRITE_BYTE_DATA;
11}
12
13/* this function returns the status-register of our i2c-device */
14static inline u32 saa7146_i2c_status(struct saa7146_dev *dev)
15{
16	u32 iicsta = saa7146_read(dev, I2C_STATUS);
17/*
18	DEB_I2C(("status: 0x%08x\n",iicsta));
19*/
20	return iicsta;
21}
22
23/* this function runs through the i2c-messages and prepares the data to be
24   sent through the saa7146. have a look at the specifications p. 122 ff
25   to understand this. it returns the number of u32s to send, or -1
26   in case of an error. */
27static int saa7146_i2c_msg_prepare(const struct i2c_msg *m, int num, u32 *op)
28{
29	int h1, h2;
30	int i, j, addr;
31	int mem = 0, op_count = 0;
32
33	/* first determine size of needed memory */
34	for(i = 0; i < num; i++) {
35		mem += m[i].len + 1;
36	}
37
38	/* worst case: we need one u32 for three bytes to be send
39	   plus one extra byte to address the device */
40	mem = 1 + ((mem-1) / 3);
41
42	/* we assume that op points to a memory of at least SAA7146_I2C_MEM bytes
43	   size. if we exceed this limit... */
44	if ( (4*mem) > SAA7146_I2C_MEM ) {
45//fm		DEB_I2C(("cannot prepare i2c-message.\n"));
46		return -ENOMEM;
47	}
48
49	/* be careful: clear out the i2c-mem first */
50	memset(op,0,sizeof(u32)*mem);
51
52	/* loop through all messages */
53	for(i = 0; i < num; i++) {
54
55		/* insert the address of the i2c-slave.
56		   note: we get 7 bit i2c-addresses,
57		   so we have to perform a translation */
58		addr = (m[i].addr*2) + ( (0 != (m[i].flags & I2C_M_RD)) ? 1 : 0);
59		h1 = op_count/3; h2 = op_count%3;
60		op[h1] |= (	    (u8)addr << ((3-h2)*8));
61		op[h1] |= (SAA7146_I2C_START << ((3-h2)*2));
62		op_count++;
63
64		/* loop through all bytes of message i */
65		for(j = 0; j < m[i].len; j++) {
66			/* insert the data bytes */
67			h1 = op_count/3; h2 = op_count%3;
68			op[h1] |= ( (u32)((u8)m[i].buf[j]) << ((3-h2)*8));
69			op[h1] |= (       SAA7146_I2C_CONT << ((3-h2)*2));
70			op_count++;
71		}
72
73	}
74
75	/* have a look at the last byte inserted:
76	  if it was: ...CONT change it to ...STOP */
77	h1 = (op_count-1)/3; h2 = (op_count-1)%3;
78	if ( SAA7146_I2C_CONT == (0x3 & (op[h1] >> ((3-h2)*2))) ) {
79		op[h1] &= ~(0x2 << ((3-h2)*2));
80		op[h1] |= (SAA7146_I2C_STOP << ((3-h2)*2));
81	}
82
83	/* return the number of u32s to send */
84	return mem;
85}
86
87/* this functions loops through all i2c-messages. normally, it should determine
88   which bytes were read through the adapter and write them back to the corresponding
89   i2c-message. but instead, we simply write back all bytes.
90   fixme: this could be improved. */
91static int saa7146_i2c_msg_cleanup(const struct i2c_msg *m, int num, u32 *op)
92{
93	int i, j;
94	int op_count = 0;
95
96	/* loop through all messages */
97	for(i = 0; i < num; i++) {
98
99		op_count++;
100
101		/* loop throgh all bytes of message i */
102		for(j = 0; j < m[i].len; j++) {
103			/* write back all bytes that could have been read */
104			m[i].buf[j] = (op[op_count/3] >> ((3-(op_count%3))*8));
105			op_count++;
106		}
107	}
108
109	return 0;
110}
111
112/* this functions resets the i2c-device and returns 0 if everything was fine, otherwise -1 */
113static int saa7146_i2c_reset(struct saa7146_dev *dev)
114{
115	/* get current status */
116	u32 status = saa7146_i2c_status(dev);
117
118	/* clear registers for sure */
119	saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
120	saa7146_write(dev, I2C_TRANSFER, 0);
121
122	/* check if any operation is still in progress */
123	if ( 0 != ( status & SAA7146_I2C_BUSY) ) {
124
125		/* yes, kill ongoing operation */
126		DEB_I2C(("busy_state detected.\n"));
127
128		/* set "ABORT-OPERATION"-bit (bit 7)*/
129		saa7146_write(dev, I2C_STATUS, (dev->i2c_bitrate | MASK_07));
130		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
131		msleep(SAA7146_I2C_DELAY);
132
133		/* clear all error-bits pending; this is needed because p.123, note 1 */
134		saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
135		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
136		msleep(SAA7146_I2C_DELAY);
137	}
138
139	/* check if any error is (still) present. (this can be necessary because p.123, note 1) */
140	status = saa7146_i2c_status(dev);
141
142	if ( dev->i2c_bitrate != status ) {
143
144		DEB_I2C(("error_state detected. status:0x%08x\n",status));
145
146		/* Repeat the abort operation. This seems to be necessary
147		   after serious protocol errors caused by e.g. the SAA7740 */
148		saa7146_write(dev, I2C_STATUS, (dev->i2c_bitrate | MASK_07));
149		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
150		msleep(SAA7146_I2C_DELAY);
151
152		/* clear all error-bits pending */
153		saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
154		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
155		msleep(SAA7146_I2C_DELAY);
156
157		/* the data sheet says it might be necessary to clear the status
158		   twice after an abort */
159		saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
160		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
161		msleep(SAA7146_I2C_DELAY);
162	}
163
164	/* if any error is still present, a fatal error has occured ... */
165	status = saa7146_i2c_status(dev);
166	if ( dev->i2c_bitrate != status ) {
167		DEB_I2C(("fatal error. status:0x%08x\n",status));
168		return -1;
169	}
170
171	return 0;
172}
173
174/* this functions writes out the data-byte 'dword' to the i2c-device.
175   it returns 0 if ok, -1 if the transfer failed, -2 if the transfer
176   failed badly (e.g. address error) */
177static int saa7146_i2c_writeout(struct saa7146_dev *dev, u32* dword, int short_delay)
178{
179	u32 status = 0, mc2 = 0;
180	int trial = 0;
181	unsigned long timeout;
182
183	/* write out i2c-command */
184	DEB_I2C(("before: 0x%08x (status: 0x%08x), %d\n",*dword,saa7146_read(dev, I2C_STATUS), dev->i2c_op));
185
186	if( 0 != (SAA7146_USE_I2C_IRQ & dev->ext->flags)) {
187
188		saa7146_write(dev, I2C_STATUS,	 dev->i2c_bitrate);
189		saa7146_write(dev, I2C_TRANSFER, *dword);
190
191		dev->i2c_op = 1;
192		SAA7146_IER_ENABLE(dev, MASK_16|MASK_17);
193		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
194
195		wait_event_interruptible(dev->i2c_wq, dev->i2c_op == 0);
196		if (signal_pending (current)) {
197			/* a signal arrived */
198			return -ERESTARTSYS;
199		}
200		status = saa7146_read(dev, I2C_STATUS);
201	} else {
202		saa7146_write(dev, I2C_STATUS,	 dev->i2c_bitrate);
203		saa7146_write(dev, I2C_TRANSFER, *dword);
204		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
205
206		/* do not poll for i2c-status before upload is complete */
207		timeout = jiffies + HZ/100 + 1; /* 10ms */
208		while(1) {
209			mc2 = (saa7146_read(dev, MC2) & 0x1);
210			if( 0 != mc2 ) {
211				break;
212			}
213			if (time_after(jiffies,timeout)) {
214				printk(KERN_WARNING "saa7146_i2c_writeout: timed out waiting for MC2\n");
215				return -EIO;
216			}
217		}
218		/* wait until we get a transfer done or error */
219		timeout = jiffies + HZ/100 + 1; /* 10ms */
220		while(1) {
221			/**
222			 *  first read usually delivers bogus results...
223			 */
224			saa7146_i2c_status(dev);
225			status = saa7146_i2c_status(dev);
226			if ((status & 0x3) != 1)
227				break;
228			if (time_after(jiffies,timeout)) {
229				/* this is normal when probing the bus
230				 * (no answer from nonexisistant device...)
231				 */
232				DEB_I2C(("saa7146_i2c_writeout: timed out waiting for end of xfer\n"));
233				return -EIO;
234			}
235			if ((++trial < 20) && short_delay)
236				udelay(10);
237			else
238			msleep(1);
239		}
240	}
241
242	/* give a detailed status report */
243	if ( 0 != (status & SAA7146_I2C_ERR)) {
244
245		if( 0 != (status & SAA7146_I2C_SPERR) ) {
246			DEB_I2C(("error due to invalid start/stop condition.\n"));
247		}
248		if( 0 != (status & SAA7146_I2C_DTERR) ) {
249			DEB_I2C(("error in data transmission.\n"));
250		}
251		if( 0 != (status & SAA7146_I2C_DRERR) ) {
252			DEB_I2C(("error when receiving data.\n"));
253		}
254		if( 0 != (status & SAA7146_I2C_AL) ) {
255			DEB_I2C(("error because arbitration lost.\n"));
256		}
257
258		/* we handle address-errors here */
259		if( 0 != (status & SAA7146_I2C_APERR) ) {
260			DEB_I2C(("error in address phase.\n"));
261			return -EREMOTEIO;
262		}
263
264		return -EIO;
265	}
266
267	/* read back data, just in case we were reading ... */
268	*dword = saa7146_read(dev, I2C_TRANSFER);
269
270	DEB_I2C(("after: 0x%08x\n",*dword));
271	return 0;
272}
273
274int saa7146_i2c_transfer(struct saa7146_dev *dev, const struct i2c_msg *msgs, int num, int retries)
275{
276	int i = 0, count = 0;
277	u32* buffer = dev->d_i2c.cpu_addr;
278	int err = 0;
279	int address_err = 0;
280	int short_delay = 0;
281
282	if (mutex_lock_interruptible(&dev->i2c_lock))
283		return -ERESTARTSYS;
284
285	for(i=0;i<num;i++) {
286		DEB_I2C(("msg:%d/%d\n",i+1,num));
287	}
288
289	/* prepare the message(s), get number of u32s to transfer */
290	count = saa7146_i2c_msg_prepare(msgs, num, buffer);
291	if ( 0 > count ) {
292		err = -1;
293		goto out;
294	}
295
296	if ( count > 3 || 0 != (SAA7146_I2C_SHORT_DELAY & dev->ext->flags) )
297		short_delay = 1;
298
299	do {
300		/* reset the i2c-device if necessary */
301		err = saa7146_i2c_reset(dev);
302		if ( 0 > err ) {
303			DEB_I2C(("could not reset i2c-device.\n"));
304			goto out;
305		}
306
307		/* write out the u32s one after another */
308		for(i = 0; i < count; i++) {
309			err = saa7146_i2c_writeout(dev, &buffer[i], short_delay);
310			if ( 0 != err) {
311				/* this one is unsatisfying: some i2c slaves on some
312				   dvb cards don't acknowledge correctly, so the saa7146
313				   thinks that an address error occured. in that case, the
314				   transaction should be retrying, even if an address error
315				   occured. analog saa7146 based cards extensively rely on
316				   i2c address probing, however, and address errors indicate that a
317				   device is really *not* there. retrying in that case
318				   increases the time the device needs to probe greatly, so
319				   it should be avoided. because of the fact, that only
320				   analog based cards use irq based i2c transactions (for dvb
321				   cards, this screwes up other interrupt sources), we bail out
322				   completely for analog cards after an address error and trust
323				   the saa7146 address error detection. */
324				if ( -EREMOTEIO == err ) {
325					if( 0 != (SAA7146_USE_I2C_IRQ & dev->ext->flags)) {
326						goto out;
327					}
328					address_err++;
329				}
330				DEB_I2C(("error while sending message(s). starting again.\n"));
331				break;
332			}
333		}
334		if( 0 == err ) {
335			err = num;
336			break;
337		}
338
339		/* delay a bit before retrying */
340		msleep(10);
341
342	} while (err != num && retries--);
343
344	/* if every retry had an address error, exit right away */
345	if (address_err == retries) {
346		goto out;
347	}
348
349	/* if any things had to be read, get the results */
350	if ( 0 != saa7146_i2c_msg_cleanup(msgs, num, buffer)) {
351		DEB_I2C(("could not cleanup i2c-message.\n"));
352		err = -1;
353		goto out;
354	}
355
356	/* return the number of delivered messages */
357	DEB_I2C(("transmission successful. (msg:%d).\n",err));
358out:
359	/* another bug in revision 0: the i2c-registers get uploaded randomly by other
360	   uploads, so we better clear them out before continueing */
361	if( 0 == dev->revision ) {
362		u32 zero = 0;
363		saa7146_i2c_reset(dev);
364		if( 0 != saa7146_i2c_writeout(dev, &zero, short_delay)) {
365			INFO(("revision 0 error. this should never happen.\n"));
366		}
367	}
368
369	mutex_unlock(&dev->i2c_lock);
370	return err;
371}
372
373/* utility functions */
374static int saa7146_i2c_xfer(struct i2c_adapter* adapter, struct i2c_msg *msg, int num)
375{
376	struct saa7146_dev* dev = i2c_get_adapdata(adapter);
377
378	/* use helper function to transfer data */
379	return saa7146_i2c_transfer(dev, msg, num, adapter->retries);
380}
381
382
383/*****************************************************************************/
384/* i2c-adapter helper functions                                              */
385#include <linux/i2c-id.h>
386
387/* exported algorithm data */
388static struct i2c_algorithm saa7146_algo = {
389	.master_xfer	= saa7146_i2c_xfer,
390	.functionality	= saa7146_i2c_func,
391};
392
393int saa7146_i2c_adapter_prepare(struct saa7146_dev *dev, struct i2c_adapter *i2c_adapter, u32 bitrate)
394{
395	DEB_EE(("bitrate: 0x%08x\n",bitrate));
396
397	/* enable i2c-port pins */
398	saa7146_write(dev, MC1, (MASK_08 | MASK_24));
399
400	dev->i2c_bitrate = bitrate;
401	saa7146_i2c_reset(dev);
402
403	if( NULL != i2c_adapter ) {
404		BUG_ON(!i2c_adapter->class);
405		i2c_set_adapdata(i2c_adapter,dev);
406		i2c_adapter->dev.parent    = &dev->pci->dev;
407		i2c_adapter->algo	   = &saa7146_algo;
408		i2c_adapter->algo_data     = NULL;
409		i2c_adapter->id		   = I2C_HW_SAA7146;
410		i2c_adapter->timeout = SAA7146_I2C_TIMEOUT;
411		i2c_adapter->retries = SAA7146_I2C_RETRIES;
412	}
413
414	return 0;
415}
416