Annotation of src/sys/dev/i2c/i2c_bitbang.c, Revision 1.4.4.1
1.4.4.1 ! ad 1: /* $NetBSD: i2c_bitbang.c,v 1.6 2006/11/16 01:32:50 christos Exp $ */
1.1 thorpej 2:
3: /*
4: * Copyright (c) 2003 Wasabi Systems, Inc.
5: * All rights reserved.
6: *
7: * Written by Jason R. Thorpe for Wasabi Systems, Inc.
8: *
9: * Redistribution and use in source and binary forms, with or without
10: * modification, are permitted provided that the following conditions
11: * are met:
12: * 1. Redistributions of source code must retain the above copyright
13: * notice, this list of conditions and the following disclaimer.
14: * 2. Redistributions in binary form must reproduce the above copyright
15: * notice, this list of conditions and the following disclaimer in the
16: * documentation and/or other materials provided with the distribution.
17: * 3. All advertising materials mentioning features or use of this software
18: * must display the following acknowledgement:
19: * This product includes software developed for the NetBSD Project by
20: * Wasabi Systems, Inc.
21: * 4. The name of Wasabi Systems, Inc. may not be used to endorse
22: * or promote products derived from this software without specific prior
23: * written permission.
24: *
25: * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
26: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27: * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28: * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
29: * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31: * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33: * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34: * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35: * POSSIBILITY OF SUCH DAMAGE.
36: */
37:
38: /*
39: * Common module for bit-bang'ing an I2C bus.
40: */
41:
42: #include <sys/param.h>
43:
44: #include <dev/i2c/i2cvar.h>
45: #include <dev/i2c/i2c_bitbang.h>
46:
1.3 christos 47: #define SETBITS(x) ops->ibo_set_bits(v, (x))
1.1 thorpej 48: #define DIR(x) ops->ibo_set_dir(v, (x))
49: #define READ ops->ibo_read_bits(v)
50:
51: #define SDA ops->ibo_bits[I2C_BIT_SDA] /* i2c signal */
52: #define SCL ops->ibo_bits[I2C_BIT_SCL] /* i2c signal */
53: #define OUTPUT ops->ibo_bits[I2C_BIT_OUTPUT] /* SDA is output */
54: #define INPUT ops->ibo_bits[I2C_BIT_INPUT] /* SDA is input */
55:
56: /*ARGSUSED*/
57: int
58: i2c_bitbang_send_start(void *v, int flags, i2c_bitbang_ops_t ops)
59: {
60:
61: DIR(OUTPUT);
62:
1.3 christos 63: SETBITS(SDA | SCL);
1.1 thorpej 64: delay(5); /* bus free time (4.7 uS) */
1.3 christos 65: SETBITS( SCL);
1.1 thorpej 66: delay(4); /* start hold time (4.0 uS) */
1.3 christos 67: SETBITS( 0);
1.1 thorpej 68: delay(5); /* clock low time (4.7 uS) */
69:
70: return (0);
71: }
72:
73: /*ARGSUSED*/
74: int
75: i2c_bitbang_send_stop(void *v, int flags, i2c_bitbang_ops_t ops)
76: {
77:
78: DIR(OUTPUT);
79:
1.3 christos 80: SETBITS( SCL);
1.1 thorpej 81: delay(4); /* stop setup time (4.0 uS) */
1.3 christos 82: SETBITS(SDA | SCL);
1.1 thorpej 83:
84: return (0);
85: }
86:
87: int
88: i2c_bitbang_initiate_xfer(void *v, i2c_addr_t addr, int flags,
89: i2c_bitbang_ops_t ops)
90: {
91:
1.4 gdamore 92: if (addr < 0x80) {
93: uint8_t i2caddr;
1.1 thorpej 94:
1.4 gdamore 95: /* disallow the 10-bit address prefix */
96: if ((addr & 0x78) == 0x78)
97: return EINVAL;
98: i2caddr = (addr << 1) | ((flags & I2C_F_READ) ? 1 : 0);
99: (void) i2c_bitbang_send_start(v, flags, ops);
100:
101: return (i2c_bitbang_write_byte(v, i2caddr,
102: flags & ~I2C_F_STOP, ops));
103:
104: } else if (addr < 0x400) {
105: uint16_t i2caddr;
106: int rv;
107:
108: i2caddr = (addr << 1) | ((flags & I2C_F_READ) ? 1 : 0) |
109: 0xf000;
110:
111: (void) i2c_bitbang_send_start(v, flags, ops);
112: rv = i2c_bitbang_write_byte(v, i2caddr >> 8,
113: flags & ~I2C_F_STOP, ops);
114: /* did a slave ack the 10-bit prefix? */
115: if (rv != 0)
116: return rv;
117:
118: /* send the lower 7-bits (+ read/write mode) */
119: return (i2c_bitbang_write_byte(v, i2caddr & 0xff,
120: flags & ~I2C_F_STOP, ops));
1.1 thorpej 121:
1.4 gdamore 122: } else
123: return EINVAL;
1.1 thorpej 124: }
125:
126: int
127: i2c_bitbang_read_byte(void *v, uint8_t *valp, int flags,
128: i2c_bitbang_ops_t ops)
129: {
130: int i;
131: uint8_t val = 0;
132: uint32_t bit;
133:
134: DIR(INPUT);
1.3 christos 135: SETBITS(SDA );
1.1 thorpej 136:
137: for (i = 0; i < 8; i++) {
138: val <<= 1;
1.3 christos 139: SETBITS(SDA | SCL);
1.1 thorpej 140: delay(4); /* clock high time (4.0 uS) */
141: if (READ & SDA)
142: val |= 1;
1.3 christos 143: SETBITS(SDA );
1.1 thorpej 144: delay(5); /* clock low time (4.7 uS) */
145: }
146:
147: bit = (flags & I2C_F_LAST) ? SDA : 0;
148: DIR(OUTPUT);
1.3 christos 149: SETBITS(bit );
1.1 thorpej 150: delay(1); /* data setup time (250 nS) */
1.3 christos 151: SETBITS(bit | SCL);
1.1 thorpej 152: delay(4); /* clock high time (4.0 uS) */
1.3 christos 153: SETBITS(bit );
1.1 thorpej 154: delay(5); /* clock low time (4.7 uS) */
155:
156: DIR(INPUT);
1.3 christos 157: SETBITS(SDA );
1.1 thorpej 158: delay(5);
159:
160: if ((flags & (I2C_F_STOP | I2C_F_LAST)) == (I2C_F_STOP | I2C_F_LAST))
161: (void) i2c_bitbang_send_stop(v, flags, ops);
162:
163: *valp = val;
164: return (0);
165: }
166:
167: int
168: i2c_bitbang_write_byte(void *v, uint8_t val, int flags,
169: i2c_bitbang_ops_t ops)
170: {
171: uint32_t bit;
172: uint8_t mask;
173: int error;
174:
175: DIR(OUTPUT);
176:
177: for (mask = 0x80; mask != 0; mask >>= 1) {
178: bit = (val & mask) ? SDA : 0;
1.3 christos 179: SETBITS(bit );
1.1 thorpej 180: delay(1); /* data setup time (250 nS) */
1.3 christos 181: SETBITS(bit | SCL);
1.1 thorpej 182: delay(4); /* clock high time (4.0 uS) */
1.3 christos 183: SETBITS(bit );
1.1 thorpej 184: delay(5); /* clock low time (4.7 uS) */
185: }
186:
187: DIR(INPUT);
188:
1.3 christos 189: SETBITS(SDA );
1.1 thorpej 190: delay(5);
1.3 christos 191: SETBITS(SDA | SCL);
1.1 thorpej 192: delay(4);
193: error = (READ & SDA) ? EIO : 0;
1.3 christos 194: SETBITS(SDA );
1.1 thorpej 195: delay(5);
196:
197: if (flags & I2C_F_STOP)
198: (void) i2c_bitbang_send_stop(v, flags, ops);
199:
200: return (error);
201: }
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