]> git.sur5r.net Git - u-boot/blob - common/soft_i2c.c
Merge with git+ssh://sr@pollux.denx.org/home/sr/git/u-boot/denx/.git
[u-boot] / common / 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 #endif
32 #ifdef CONFIG_AT91RM9200DK              /* need this for the at91rm9200dk */
33 #include <asm/io.h>
34 #include <asm/arch/hardware.h>
35 #endif
36 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
37 #include <asm/arch/ixp425.h>
38 #endif
39 #include <i2c.h>
40
41 #if defined(CONFIG_SOFT_I2C)
42
43 /* #define      DEBUG_I2C       */
44
45 #ifdef DEBUG_I2C
46 DECLARE_GLOBAL_DATA_PTR;
47 #endif
48
49
50 /*-----------------------------------------------------------------------
51  * Definitions
52  */
53
54 #define RETRIES         0
55
56
57 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
58 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
59
60
61 #ifdef DEBUG_I2C
62 #define PRINTD(fmt,args...)     do {    \
63         if (gd->have_console)           \
64                 printf (fmt ,##args);   \
65         } while (0)
66 #else
67 #define PRINTD(fmt,args...)
68 #endif
69
70 /*-----------------------------------------------------------------------
71  * Local functions
72  */
73 static void  send_reset (void);
74 static void  send_start (void);
75 static void  send_stop  (void);
76 static void  send_ack   (int);
77 static int   write_byte (uchar byte);
78 static uchar read_byte  (int);
79
80
81 /*-----------------------------------------------------------------------
82  * Send a reset sequence consisting of 9 clocks with the data signal high
83  * to clock any confused device back into an idle state.  Also send a
84  * <stop> at the end of the sequence for belts & suspenders.
85  */
86 static void send_reset(void)
87 {
88 #ifdef  CONFIG_MPC8260
89         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
90 #endif
91 #ifdef  CONFIG_8xx
92         volatile immap_t *immr = (immap_t *)CFG_IMMR;
93 #endif
94         int j;
95
96         I2C_SCL(1);
97         I2C_SDA(1);
98 #ifdef  I2C_INIT
99         I2C_INIT;
100 #endif
101         I2C_TRISTATE;
102         for(j = 0; j < 9; j++) {
103                 I2C_SCL(0);
104                 I2C_DELAY;
105                 I2C_DELAY;
106                 I2C_SCL(1);
107                 I2C_DELAY;
108                 I2C_DELAY;
109         }
110         send_stop();
111         I2C_TRISTATE;
112 }
113
114 /*-----------------------------------------------------------------------
115  * START: High -> Low on SDA while SCL is High
116  */
117 static void send_start(void)
118 {
119 #ifdef  CONFIG_MPC8260
120         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
121 #endif
122 #ifdef  CONFIG_8xx
123         volatile immap_t *immr = (immap_t *)CFG_IMMR;
124 #endif
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 #ifdef  CONFIG_MPC8260
142         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
143 #endif
144 #ifdef  CONFIG_8xx
145         volatile immap_t *immr = (immap_t *)CFG_IMMR;
146 #endif
147
148         I2C_SCL(0);
149         I2C_DELAY;
150         I2C_SDA(0);
151         I2C_ACTIVE;
152         I2C_DELAY;
153         I2C_SCL(1);
154         I2C_DELAY;
155         I2C_SDA(1);
156         I2C_DELAY;
157         I2C_TRISTATE;
158 }
159
160
161 /*-----------------------------------------------------------------------
162  * ack should be I2C_ACK or I2C_NOACK
163  */
164 static void send_ack(int ack)
165 {
166 #ifdef  CONFIG_MPC8260
167         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
168 #endif
169 #ifdef  CONFIG_8xx
170         volatile immap_t *immr = (immap_t *)CFG_IMMR;
171 #endif
172
173         I2C_SCL(0);
174         I2C_DELAY;
175         I2C_ACTIVE;
176         I2C_SDA(ack);
177         I2C_DELAY;
178         I2C_SCL(1);
179         I2C_DELAY;
180         I2C_DELAY;
181         I2C_SCL(0);
182         I2C_DELAY;
183 }
184
185
186 /*-----------------------------------------------------------------------
187  * Send 8 bits and look for an acknowledgement.
188  */
189 static int write_byte(uchar data)
190 {
191 #ifdef  CONFIG_MPC8260
192         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
193 #endif
194 #ifdef  CONFIG_8xx
195         volatile immap_t *immr = (immap_t *)CFG_IMMR;
196 #endif
197         int j;
198         int nack;
199
200         I2C_ACTIVE;
201         for(j = 0; j < 8; j++) {
202                 I2C_SCL(0);
203                 I2C_DELAY;
204                 I2C_SDA(data & 0x80);
205                 I2C_DELAY;
206                 I2C_SCL(1);
207                 I2C_DELAY;
208                 I2C_DELAY;
209
210                 data <<= 1;
211         }
212
213         /*
214          * Look for an <ACK>(negative logic) and return it.
215          */
216         I2C_SCL(0);
217         I2C_DELAY;
218         I2C_SDA(1);
219         I2C_TRISTATE;
220         I2C_DELAY;
221         I2C_SCL(1);
222         I2C_DELAY;
223         I2C_DELAY;
224         nack = I2C_READ;
225         I2C_SCL(0);
226         I2C_DELAY;
227         I2C_ACTIVE;
228
229         return(nack);   /* not a nack is an ack */
230 }
231
232
233 /*-----------------------------------------------------------------------
234  * if ack == I2C_ACK, ACK the byte so can continue reading, else
235  * send I2C_NOACK to end the read.
236  */
237 static uchar read_byte(int ack)
238 {
239 #ifdef  CONFIG_MPC8260
240         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
241 #endif
242 #ifdef  CONFIG_8xx
243         volatile immap_t *immr = (immap_t *)CFG_IMMR;
244 #endif
245         int  data;
246         int  j;
247
248         /*
249          * Read 8 bits, MSB first.
250          */
251         I2C_TRISTATE;
252         data = 0;
253         for(j = 0; j < 8; j++) {
254                 I2C_SCL(0);
255                 I2C_DELAY;
256                 I2C_SCL(1);
257                 I2C_DELAY;
258                 data <<= 1;
259                 data |= I2C_READ;
260                 I2C_DELAY;
261         }
262         send_ack(ack);
263
264         return(data);
265 }
266
267 /*=====================================================================*/
268 /*                         Public Functions                            */
269 /*=====================================================================*/
270
271 /*-----------------------------------------------------------------------
272  * Initialization
273  */
274 void i2c_init (int speed, int slaveaddr)
275 {
276         /*
277          * WARNING: Do NOT save speed in a static variable: if the
278          * I2C routines are called before RAM is initialized (to read
279          * the DIMM SPD, for instance), RAM won't be usable and your
280          * system will crash.
281          */
282         send_reset ();
283 }
284
285 /*-----------------------------------------------------------------------
286  * Probe to see if a chip is present.  Also good for checking for the
287  * completion of EEPROM writes since the chip stops responding until
288  * the write completes (typically 10mSec).
289  */
290 int i2c_probe(uchar addr)
291 {
292         int rc;
293
294         /*
295          * perform 1 byte write transaction with just address byte
296          * (fake write)
297          */
298         send_start();
299         rc = write_byte ((addr << 1) | 0);
300         send_stop();
301
302         return (rc ? 1 : 0);
303 }
304
305 /*-----------------------------------------------------------------------
306  * Read bytes
307  */
308 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
309 {
310         int shift;
311         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
312                 chip, addr, alen, buffer, len);
313
314 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
315         /*
316          * EEPROM chips that implement "address overflow" are ones
317          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
318          * address and the extra bits end up in the "chip address"
319          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
320          * four 256 byte chips.
321          *
322          * Note that we consider the length of the address field to
323          * still be one byte because the extra address bits are
324          * hidden in the chip address.
325          */
326         chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
327
328         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
329                 chip, addr);
330 #endif
331
332         /*
333          * Do the addressing portion of a write cycle to set the
334          * chip's address pointer.  If the address length is zero,
335          * don't do the normal write cycle to set the address pointer,
336          * there is no address pointer in this chip.
337          */
338         send_start();
339         if(alen > 0) {
340                 if(write_byte(chip << 1)) {     /* write cycle */
341                         send_stop();
342                         PRINTD("i2c_read, no chip responded %02X\n", chip);
343                         return(1);
344                 }
345                 shift = (alen-1) * 8;
346                 while(alen-- > 0) {
347                         if(write_byte(addr >> shift)) {
348                                 PRINTD("i2c_read, address not <ACK>ed\n");
349                                 return(1);
350                         }
351                         shift -= 8;
352                 }
353                 send_stop();    /* reportedly some chips need a full stop */
354                 send_start();
355         }
356         /*
357          * Send the chip address again, this time for a read cycle.
358          * Then read the data.  On the last byte, we do a NACK instead
359          * of an ACK(len == 0) to terminate the read.
360          */
361         write_byte((chip << 1) | 1);    /* read cycle */
362         while(len-- > 0) {
363                 *buffer++ = read_byte(len == 0);
364         }
365         send_stop();
366         return(0);
367 }
368
369 /*-----------------------------------------------------------------------
370  * Write bytes
371  */
372 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
373 {
374         int shift, failures = 0;
375
376         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
377                 chip, addr, alen, buffer, len);
378
379         send_start();
380         if(write_byte(chip << 1)) {     /* write cycle */
381                 send_stop();
382                 PRINTD("i2c_write, no chip responded %02X\n", chip);
383                 return(1);
384         }
385         shift = (alen-1) * 8;
386         while(alen-- > 0) {
387                 if(write_byte(addr >> shift)) {
388                         PRINTD("i2c_write, address not <ACK>ed\n");
389                         return(1);
390                 }
391                 shift -= 8;
392         }
393
394         while(len-- > 0) {
395                 if(write_byte(*buffer++)) {
396                         failures++;
397                 }
398         }
399         send_stop();
400         return(failures);
401 }
402
403 /*-----------------------------------------------------------------------
404  * Read a register
405  */
406 uchar i2c_reg_read(uchar i2c_addr, uchar reg)
407 {
408         uchar buf;
409
410         i2c_read(i2c_addr, reg, 1, &buf, 1);
411
412         return(buf);
413 }
414
415 /*-----------------------------------------------------------------------
416  * Write a register
417  */
418 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
419 {
420         i2c_write(i2c_addr, reg, 1, &val, 1);
421 }
422
423
424 #endif  /* CONFIG_SOFT_I2C */