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[u-boot] / drivers / i2c / soft_i2c.c
1 /*
2  * (C) Copyright 2001, 2002
3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4  *
5  * See file CREDITS for list of people who contributed to this
6  * project.
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License as
10  * published by the Free Software Foundation; either version 2 of
11  * the License, or (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21  * MA 02111-1307 USA
22  *
23  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
24  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
25  * Neil Russell.
26  */
27
28 #include <common.h>
29 #ifdef  CONFIG_MPC8260                  /* only valid for MPC8260 */
30 #include <ioports.h>
31 #include <asm/io.h>
32 #endif
33 #ifdef  CONFIG_AT91RM9200               /* need this for the at91rm9200 */
34 #include <asm/io.h>
35 #include <asm/arch/hardware.h>
36 #endif
37 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
38 #include <asm/arch/ixp425.h>
39 #endif
40 #ifdef CONFIG_LPC2292
41 #include <asm/arch/hardware.h>
42 #endif
43 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
44 #include <asm/io.h>
45 #endif
46 #include <i2c.h>
47
48 /* #define      DEBUG_I2C       */
49
50 #ifdef DEBUG_I2C
51 DECLARE_GLOBAL_DATA_PTR;
52 #endif
53
54 /*-----------------------------------------------------------------------
55  * Definitions
56  */
57
58 #define RETRIES         0
59
60 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
61 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
62
63
64 #ifdef DEBUG_I2C
65 #define PRINTD(fmt,args...)     do {    \
66         if (gd->have_console)           \
67                 printf (fmt ,##args);   \
68         } while (0)
69 #else
70 #define PRINTD(fmt,args...)
71 #endif
72
73 #if defined(CONFIG_I2C_MULTI_BUS)
74 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
75 #endif /* CONFIG_I2C_MULTI_BUS */
76
77 /*-----------------------------------------------------------------------
78  * Local functions
79  */
80 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
81 static void  send_reset (void);
82 #endif
83 static void  send_start (void);
84 static void  send_stop  (void);
85 static void  send_ack   (int);
86 static int   write_byte (uchar byte);
87 static uchar read_byte  (int);
88
89 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
90 /*-----------------------------------------------------------------------
91  * Send a reset sequence consisting of 9 clocks with the data signal high
92  * to clock any confused device back into an idle state.  Also send a
93  * <stop> at the end of the sequence for belts & suspenders.
94  */
95 static void send_reset(void)
96 {
97         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
98         int j;
99
100         I2C_SCL(1);
101         I2C_SDA(1);
102 #ifdef  I2C_INIT
103         I2C_INIT;
104 #endif
105         I2C_TRISTATE;
106         for(j = 0; j < 9; j++) {
107                 I2C_SCL(0);
108                 I2C_DELAY;
109                 I2C_DELAY;
110                 I2C_SCL(1);
111                 I2C_DELAY;
112                 I2C_DELAY;
113         }
114         send_stop();
115         I2C_TRISTATE;
116 }
117 #endif
118
119 /*-----------------------------------------------------------------------
120  * START: High -> Low on SDA while SCL is High
121  */
122 static void send_start(void)
123 {
124         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
125
126         I2C_DELAY;
127         I2C_SDA(1);
128         I2C_ACTIVE;
129         I2C_DELAY;
130         I2C_SCL(1);
131         I2C_DELAY;
132         I2C_SDA(0);
133         I2C_DELAY;
134 }
135
136 /*-----------------------------------------------------------------------
137  * STOP: Low -> High on SDA while SCL is High
138  */
139 static void send_stop(void)
140 {
141         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
142
143         I2C_SCL(0);
144         I2C_DELAY;
145         I2C_SDA(0);
146         I2C_ACTIVE;
147         I2C_DELAY;
148         I2C_SCL(1);
149         I2C_DELAY;
150         I2C_SDA(1);
151         I2C_DELAY;
152         I2C_TRISTATE;
153 }
154
155 /*-----------------------------------------------------------------------
156  * ack should be I2C_ACK or I2C_NOACK
157  */
158 static void send_ack(int ack)
159 {
160         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
161
162         I2C_SCL(0);
163         I2C_DELAY;
164         I2C_ACTIVE;
165         I2C_SDA(ack);
166         I2C_DELAY;
167         I2C_SCL(1);
168         I2C_DELAY;
169         I2C_DELAY;
170         I2C_SCL(0);
171         I2C_DELAY;
172 }
173
174 /*-----------------------------------------------------------------------
175  * Send 8 bits and look for an acknowledgement.
176  */
177 static int write_byte(uchar data)
178 {
179         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
180         int j;
181         int nack;
182
183         I2C_ACTIVE;
184         for(j = 0; j < 8; j++) {
185                 I2C_SCL(0);
186                 I2C_DELAY;
187                 I2C_SDA(data & 0x80);
188                 I2C_DELAY;
189                 I2C_SCL(1);
190                 I2C_DELAY;
191                 I2C_DELAY;
192
193                 data <<= 1;
194         }
195
196         /*
197          * Look for an <ACK>(negative logic) and return it.
198          */
199         I2C_SCL(0);
200         I2C_DELAY;
201         I2C_SDA(1);
202         I2C_TRISTATE;
203         I2C_DELAY;
204         I2C_SCL(1);
205         I2C_DELAY;
206         I2C_DELAY;
207         nack = I2C_READ;
208         I2C_SCL(0);
209         I2C_DELAY;
210         I2C_ACTIVE;
211
212         return(nack);   /* not a nack is an ack */
213 }
214
215 #if defined(CONFIG_I2C_MULTI_BUS)
216 /*
217  * Functions for multiple I2C bus handling
218  */
219 unsigned int i2c_get_bus_num(void)
220 {
221         return i2c_bus_num;
222 }
223
224 int i2c_set_bus_num(unsigned int bus)
225 {
226 #if defined(CONFIG_I2C_MUX)
227         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
228                 i2c_bus_num = bus;
229         } else {
230                 int     ret;
231
232                 ret = i2x_mux_select_mux(bus);
233                 if (ret == 0)
234                         i2c_bus_num = bus;
235                 else
236                         return ret;
237         }
238 #else
239         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
240                 return -1;
241         i2c_bus_num = bus;
242 #endif
243         return 0;
244 }
245 #endif
246
247 /* TODO: add 100/400k switching */
248 unsigned int i2c_get_bus_speed(void)
249 {
250         return CONFIG_SYS_I2C_SPEED;
251 }
252
253 int i2c_set_bus_speed(unsigned int speed)
254 {
255         if (speed != CONFIG_SYS_I2C_SPEED)
256                 return -1;
257
258         return 0;
259 }
260
261 /*-----------------------------------------------------------------------
262  * if ack == I2C_ACK, ACK the byte so can continue reading, else
263  * send I2C_NOACK to end the read.
264  */
265 static uchar read_byte(int ack)
266 {
267         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
268         int  data;
269         int  j;
270
271         /*
272          * Read 8 bits, MSB first.
273          */
274         I2C_TRISTATE;
275         I2C_SDA(1);
276         data = 0;
277         for(j = 0; j < 8; j++) {
278                 I2C_SCL(0);
279                 I2C_DELAY;
280                 I2C_SCL(1);
281                 I2C_DELAY;
282                 data <<= 1;
283                 data |= I2C_READ;
284                 I2C_DELAY;
285         }
286         send_ack(ack);
287
288         return(data);
289 }
290
291 /*=====================================================================*/
292 /*                         Public Functions                            */
293 /*=====================================================================*/
294
295 /*-----------------------------------------------------------------------
296  * Initialization
297  */
298 void i2c_init (int speed, int slaveaddr)
299 {
300 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
301         /* call board specific i2c bus reset routine before accessing the   */
302         /* environment, which might be in a chip on that bus. For details   */
303         /* about this problem see doc/I2C_Edge_Conditions.                  */
304         i2c_init_board();
305 #else
306         /*
307          * WARNING: Do NOT save speed in a static variable: if the
308          * I2C routines are called before RAM is initialized (to read
309          * the DIMM SPD, for instance), RAM won't be usable and your
310          * system will crash.
311          */
312         send_reset ();
313 #endif
314 }
315
316 /*-----------------------------------------------------------------------
317  * Probe to see if a chip is present.  Also good for checking for the
318  * completion of EEPROM writes since the chip stops responding until
319  * the write completes (typically 10mSec).
320  */
321 int i2c_probe(uchar addr)
322 {
323         int rc;
324
325         /*
326          * perform 1 byte write transaction with just address byte
327          * (fake write)
328          */
329         send_start();
330         rc = write_byte ((addr << 1) | 0);
331         send_stop();
332
333         return (rc ? 1 : 0);
334 }
335
336 /*-----------------------------------------------------------------------
337  * Read bytes
338  */
339 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
340 {
341         int shift;
342         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
343                 chip, addr, alen, buffer, len);
344
345 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
346         /*
347          * EEPROM chips that implement "address overflow" are ones
348          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
349          * address and the extra bits end up in the "chip address"
350          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
351          * four 256 byte chips.
352          *
353          * Note that we consider the length of the address field to
354          * still be one byte because the extra address bits are
355          * hidden in the chip address.
356          */
357         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
358
359         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
360                 chip, addr);
361 #endif
362
363         /*
364          * Do the addressing portion of a write cycle to set the
365          * chip's address pointer.  If the address length is zero,
366          * don't do the normal write cycle to set the address pointer,
367          * there is no address pointer in this chip.
368          */
369         send_start();
370         if(alen > 0) {
371                 if(write_byte(chip << 1)) {     /* write cycle */
372                         send_stop();
373                         PRINTD("i2c_read, no chip responded %02X\n", chip);
374                         return(1);
375                 }
376                 shift = (alen-1) * 8;
377                 while(alen-- > 0) {
378                         if(write_byte(addr >> shift)) {
379                                 PRINTD("i2c_read, address not <ACK>ed\n");
380                                 return(1);
381                         }
382                         shift -= 8;
383                 }
384
385                 /* Some I2C chips need a stop/start sequence here,
386                  * other chips don't work with a full stop and need
387                  * only a start.  Default behaviour is to send the
388                  * stop/start sequence.
389                  */
390 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
391                 send_start();
392 #else
393                 send_stop();
394                 send_start();
395 #endif
396         }
397         /*
398          * Send the chip address again, this time for a read cycle.
399          * Then read the data.  On the last byte, we do a NACK instead
400          * of an ACK(len == 0) to terminate the read.
401          */
402         write_byte((chip << 1) | 1);    /* read cycle */
403         while(len-- > 0) {
404                 *buffer++ = read_byte(len == 0);
405         }
406         send_stop();
407         return(0);
408 }
409
410 /*-----------------------------------------------------------------------
411  * Write bytes
412  */
413 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
414 {
415         int shift, failures = 0;
416
417         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
418                 chip, addr, alen, buffer, len);
419
420         send_start();
421         if(write_byte(chip << 1)) {     /* write cycle */
422                 send_stop();
423                 PRINTD("i2c_write, no chip responded %02X\n", chip);
424                 return(1);
425         }
426         shift = (alen-1) * 8;
427         while(alen-- > 0) {
428                 if(write_byte(addr >> shift)) {
429                         PRINTD("i2c_write, address not <ACK>ed\n");
430                         return(1);
431                 }
432                 shift -= 8;
433         }
434
435         while(len-- > 0) {
436                 if(write_byte(*buffer++)) {
437                         failures++;
438                 }
439         }
440         send_stop();
441         return(failures);
442 }