SPL: Add support for loading image from ram in SPL.
[oweals/u-boot.git] / 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 #if defined(CONFIG_AT91FAMILY)
34 #include <asm/io.h>
35 #include <asm/arch/hardware.h>
36 #include <asm/arch/at91_pio.h>
37 #ifdef CONFIG_AT91_LEGACY
38 #include <asm/arch/gpio.h>
39 #endif
40 #endif
41 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
42 #include <asm/arch/ixp425.h>
43 #endif
44 #ifdef CONFIG_LPC2292
45 #include <asm/arch/hardware.h>
46 #endif
47 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
48 #include <asm/io.h>
49 #endif
50 #include <i2c.h>
51
52 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
53 # include <asm/gpio.h>
54
55 # ifndef I2C_GPIO_SYNC
56 #  define I2C_GPIO_SYNC
57 # endif
58
59 # ifndef I2C_INIT
60 #  define I2C_INIT \
61         do { \
62                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
63                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
64         } while (0)
65 # endif
66
67 # ifndef I2C_ACTIVE
68 #  define I2C_ACTIVE do { } while (0)
69 # endif
70
71 # ifndef I2C_TRISTATE
72 #  define I2C_TRISTATE do { } while (0)
73 # endif
74
75 # ifndef I2C_READ
76 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
77 # endif
78
79 # ifndef I2C_SDA
80 #  define I2C_SDA(bit) \
81         do { \
82                 if (bit) \
83                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
84                 else \
85                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
86                 I2C_GPIO_SYNC; \
87         } while (0)
88 # endif
89
90 # ifndef I2C_SCL
91 #  define I2C_SCL(bit) \
92         do { \
93                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
94                 I2C_GPIO_SYNC; \
95         } while (0)
96 # endif
97
98 # ifndef I2C_DELAY
99 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
100 # endif
101
102 #endif
103
104 /* #define      DEBUG_I2C       */
105
106 #ifdef DEBUG_I2C
107 DECLARE_GLOBAL_DATA_PTR;
108 #endif
109
110 /*-----------------------------------------------------------------------
111  * Definitions
112  */
113
114 #define RETRIES         0
115
116 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
117 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
118
119
120 #ifdef DEBUG_I2C
121 #define PRINTD(fmt,args...)     do {    \
122                 printf (fmt ,##args);   \
123         } while (0)
124 #else
125 #define PRINTD(fmt,args...)
126 #endif
127
128 #if defined(CONFIG_I2C_MULTI_BUS)
129 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
130 #endif /* CONFIG_I2C_MULTI_BUS */
131
132 /*-----------------------------------------------------------------------
133  * Local functions
134  */
135 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
136 static void  send_reset (void);
137 #endif
138 static void  send_start (void);
139 static void  send_stop  (void);
140 static void  send_ack   (int);
141 static int   write_byte (uchar byte);
142 static uchar read_byte  (int);
143
144 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
145 /*-----------------------------------------------------------------------
146  * Send a reset sequence consisting of 9 clocks with the data signal high
147  * to clock any confused device back into an idle state.  Also send a
148  * <stop> at the end of the sequence for belts & suspenders.
149  */
150 static void send_reset(void)
151 {
152         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
153         int j;
154
155         I2C_SCL(1);
156         I2C_SDA(1);
157 #ifdef  I2C_INIT
158         I2C_INIT;
159 #endif
160         I2C_TRISTATE;
161         for(j = 0; j < 9; j++) {
162                 I2C_SCL(0);
163                 I2C_DELAY;
164                 I2C_DELAY;
165                 I2C_SCL(1);
166                 I2C_DELAY;
167                 I2C_DELAY;
168         }
169         send_stop();
170         I2C_TRISTATE;
171 }
172 #endif
173
174 /*-----------------------------------------------------------------------
175  * START: High -> Low on SDA while SCL is High
176  */
177 static void send_start(void)
178 {
179         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
180
181         I2C_DELAY;
182         I2C_SDA(1);
183         I2C_ACTIVE;
184         I2C_DELAY;
185         I2C_SCL(1);
186         I2C_DELAY;
187         I2C_SDA(0);
188         I2C_DELAY;
189 }
190
191 /*-----------------------------------------------------------------------
192  * STOP: Low -> High on SDA while SCL is High
193  */
194 static void send_stop(void)
195 {
196         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
197
198         I2C_SCL(0);
199         I2C_DELAY;
200         I2C_SDA(0);
201         I2C_ACTIVE;
202         I2C_DELAY;
203         I2C_SCL(1);
204         I2C_DELAY;
205         I2C_SDA(1);
206         I2C_DELAY;
207         I2C_TRISTATE;
208 }
209
210 /*-----------------------------------------------------------------------
211  * ack should be I2C_ACK or I2C_NOACK
212  */
213 static void send_ack(int ack)
214 {
215         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
216
217         I2C_SCL(0);
218         I2C_DELAY;
219         I2C_ACTIVE;
220         I2C_SDA(ack);
221         I2C_DELAY;
222         I2C_SCL(1);
223         I2C_DELAY;
224         I2C_DELAY;
225         I2C_SCL(0);
226         I2C_DELAY;
227 }
228
229 /*-----------------------------------------------------------------------
230  * Send 8 bits and look for an acknowledgement.
231  */
232 static int write_byte(uchar data)
233 {
234         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
235         int j;
236         int nack;
237
238         I2C_ACTIVE;
239         for(j = 0; j < 8; j++) {
240                 I2C_SCL(0);
241                 I2C_DELAY;
242                 I2C_SDA(data & 0x80);
243                 I2C_DELAY;
244                 I2C_SCL(1);
245                 I2C_DELAY;
246                 I2C_DELAY;
247
248                 data <<= 1;
249         }
250
251         /*
252          * Look for an <ACK>(negative logic) and return it.
253          */
254         I2C_SCL(0);
255         I2C_DELAY;
256         I2C_SDA(1);
257         I2C_TRISTATE;
258         I2C_DELAY;
259         I2C_SCL(1);
260         I2C_DELAY;
261         I2C_DELAY;
262         nack = I2C_READ;
263         I2C_SCL(0);
264         I2C_DELAY;
265         I2C_ACTIVE;
266
267         return(nack);   /* not a nack is an ack */
268 }
269
270 #if defined(CONFIG_I2C_MULTI_BUS)
271 /*
272  * Functions for multiple I2C bus handling
273  */
274 unsigned int i2c_get_bus_num(void)
275 {
276         return i2c_bus_num;
277 }
278
279 int i2c_set_bus_num(unsigned int bus)
280 {
281 #if defined(CONFIG_I2C_MUX)
282         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
283                 i2c_bus_num = bus;
284         } else {
285                 int     ret;
286
287                 ret = i2x_mux_select_mux(bus);
288                 i2c_init_board();
289                 if (ret == 0)
290                         i2c_bus_num = bus;
291                 else
292                         return ret;
293         }
294 #else
295         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
296                 return -1;
297         i2c_bus_num = bus;
298 #endif
299         return 0;
300 }
301 #endif
302
303 /*-----------------------------------------------------------------------
304  * if ack == I2C_ACK, ACK the byte so can continue reading, else
305  * send I2C_NOACK to end the read.
306  */
307 static uchar read_byte(int ack)
308 {
309         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
310         int  data;
311         int  j;
312
313         /*
314          * Read 8 bits, MSB first.
315          */
316         I2C_TRISTATE;
317         I2C_SDA(1);
318         data = 0;
319         for(j = 0; j < 8; j++) {
320                 I2C_SCL(0);
321                 I2C_DELAY;
322                 I2C_SCL(1);
323                 I2C_DELAY;
324                 data <<= 1;
325                 data |= I2C_READ;
326                 I2C_DELAY;
327         }
328         send_ack(ack);
329
330         return(data);
331 }
332
333 /*=====================================================================*/
334 /*                         Public Functions                            */
335 /*=====================================================================*/
336
337 /*-----------------------------------------------------------------------
338  * Initialization
339  */
340 void i2c_init (int speed, int slaveaddr)
341 {
342 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
343         /* call board specific i2c bus reset routine before accessing the   */
344         /* environment, which might be in a chip on that bus. For details   */
345         /* about this problem see doc/I2C_Edge_Conditions.                  */
346         i2c_init_board();
347 #else
348         /*
349          * WARNING: Do NOT save speed in a static variable: if the
350          * I2C routines are called before RAM is initialized (to read
351          * the DIMM SPD, for instance), RAM won't be usable and your
352          * system will crash.
353          */
354         send_reset ();
355 #endif
356 }
357
358 /*-----------------------------------------------------------------------
359  * Probe to see if a chip is present.  Also good for checking for the
360  * completion of EEPROM writes since the chip stops responding until
361  * the write completes (typically 10mSec).
362  */
363 int i2c_probe(uchar addr)
364 {
365         int rc;
366
367         /*
368          * perform 1 byte write transaction with just address byte
369          * (fake write)
370          */
371         send_start();
372         rc = write_byte ((addr << 1) | 0);
373         send_stop();
374
375         return (rc ? 1 : 0);
376 }
377
378 /*-----------------------------------------------------------------------
379  * Read bytes
380  */
381 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
382 {
383         int shift;
384         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
385                 chip, addr, alen, buffer, len);
386
387 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
388         /*
389          * EEPROM chips that implement "address overflow" are ones
390          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
391          * address and the extra bits end up in the "chip address"
392          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
393          * four 256 byte chips.
394          *
395          * Note that we consider the length of the address field to
396          * still be one byte because the extra address bits are
397          * hidden in the chip address.
398          */
399         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
400
401         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
402                 chip, addr);
403 #endif
404
405         /*
406          * Do the addressing portion of a write cycle to set the
407          * chip's address pointer.  If the address length is zero,
408          * don't do the normal write cycle to set the address pointer,
409          * there is no address pointer in this chip.
410          */
411         send_start();
412         if(alen > 0) {
413                 if(write_byte(chip << 1)) {     /* write cycle */
414                         send_stop();
415                         PRINTD("i2c_read, no chip responded %02X\n", chip);
416                         return(1);
417                 }
418                 shift = (alen-1) * 8;
419                 while(alen-- > 0) {
420                         if(write_byte(addr >> shift)) {
421                                 PRINTD("i2c_read, address not <ACK>ed\n");
422                                 return(1);
423                         }
424                         shift -= 8;
425                 }
426
427                 /* Some I2C chips need a stop/start sequence here,
428                  * other chips don't work with a full stop and need
429                  * only a start.  Default behaviour is to send the
430                  * stop/start sequence.
431                  */
432 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
433                 send_start();
434 #else
435                 send_stop();
436                 send_start();
437 #endif
438         }
439         /*
440          * Send the chip address again, this time for a read cycle.
441          * Then read the data.  On the last byte, we do a NACK instead
442          * of an ACK(len == 0) to terminate the read.
443          */
444         write_byte((chip << 1) | 1);    /* read cycle */
445         while(len-- > 0) {
446                 *buffer++ = read_byte(len == 0);
447         }
448         send_stop();
449         return(0);
450 }
451
452 /*-----------------------------------------------------------------------
453  * Write bytes
454  */
455 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
456 {
457         int shift, failures = 0;
458
459         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
460                 chip, addr, alen, buffer, len);
461
462         send_start();
463         if(write_byte(chip << 1)) {     /* write cycle */
464                 send_stop();
465                 PRINTD("i2c_write, no chip responded %02X\n", chip);
466                 return(1);
467         }
468         shift = (alen-1) * 8;
469         while(alen-- > 0) {
470                 if(write_byte(addr >> shift)) {
471                         PRINTD("i2c_write, address not <ACK>ed\n");
472                         return(1);
473                 }
474                 shift -= 8;
475         }
476
477         while(len-- > 0) {
478                 if(write_byte(*buffer++)) {
479                         failures++;
480                 }
481         }
482         send_stop();
483         return(failures);
484 }