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Annotation of src/sys/dev/i2c/i2c_bitbang.c, Revision 1.1.4.2

1.1.4.2 ! skrll       1: /*     $NetBSD: i2c_bitbang.c,v 1.1.4.1 2004/08/03 10:46:05 skrll Exp $        */
        !             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:
        !            47: #define        SET(x)          ops->ibo_set_bits(v, (x))
        !            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:
        !            63:        SET(SDA | SCL);
        !            64:        delay(5);               /* bus free time (4.7 uS) */
        !            65:        SET(      SCL);
        !            66:        delay(4);               /* start hold time (4.0 uS) */
        !            67:        SET(        0);
        !            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:
        !            80:        SET(      SCL);
        !            81:        delay(4);               /* stop setup time (4.0 uS) */
        !            82:        SET(SDA | SCL);
        !            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:        int i2caddr;
        !            92:
        !            93:        /* XXX Only support 7-bit addressing for now. */
        !            94:        if ((addr & 0x78) == 0x78)
        !            95:                return (EINVAL);
        !            96:
        !            97:        i2caddr = (addr << 1) | ((flags & I2C_F_READ) ? 1 : 0);
        !            98:
        !            99:        (void) i2c_bitbang_send_start(v, flags, ops);
        !           100:        return (i2c_bitbang_write_byte(v, i2caddr, flags & ~I2C_F_STOP, ops));
        !           101: }
        !           102:
        !           103: int
        !           104: i2c_bitbang_read_byte(void *v, uint8_t *valp, int flags,
        !           105:     i2c_bitbang_ops_t ops)
        !           106: {
        !           107:        int i;
        !           108:        uint8_t val = 0;
        !           109:        uint32_t bit;
        !           110:
        !           111:        DIR(INPUT);
        !           112:        SET(SDA      );
        !           113:
        !           114:        for (i = 0; i < 8; i++) {
        !           115:                val <<= 1;
        !           116:                SET(SDA | SCL);
        !           117:                delay(4);       /* clock high time (4.0 uS) */
        !           118:                if (READ & SDA)
        !           119:                        val |= 1;
        !           120:                SET(SDA      );
        !           121:                delay(5);       /* clock low time (4.7 uS) */
        !           122:        }
        !           123:
        !           124:        bit = (flags & I2C_F_LAST) ? SDA : 0;
        !           125:        DIR(OUTPUT);
        !           126:        SET(bit      );
        !           127:        delay(1);       /* data setup time (250 nS) */
        !           128:        SET(bit | SCL);
        !           129:        delay(4);       /* clock high time (4.0 uS) */
        !           130:        SET(bit      );
        !           131:        delay(5);       /* clock low time (4.7 uS) */
        !           132:
        !           133:        DIR(INPUT);
        !           134:        SET(SDA      );
        !           135:        delay(5);
        !           136:
        !           137:        if ((flags & (I2C_F_STOP | I2C_F_LAST)) == (I2C_F_STOP | I2C_F_LAST))
        !           138:                (void) i2c_bitbang_send_stop(v, flags, ops);
        !           139:
        !           140:        *valp = val;
        !           141:        return (0);
        !           142: }
        !           143:
        !           144: int
        !           145: i2c_bitbang_write_byte(void *v, uint8_t val, int flags,
        !           146:     i2c_bitbang_ops_t ops)
        !           147: {
        !           148:        uint32_t bit;
        !           149:        uint8_t mask;
        !           150:        int error;
        !           151:
        !           152:        DIR(OUTPUT);
        !           153:
        !           154:        for (mask = 0x80; mask != 0; mask >>= 1) {
        !           155:                bit = (val & mask) ? SDA : 0;
        !           156:                SET(bit      );
        !           157:                delay(1);       /* data setup time (250 nS) */
        !           158:                SET(bit | SCL);
        !           159:                delay(4);       /* clock high time (4.0 uS) */
        !           160:                SET(bit      );
        !           161:                delay(5);       /* clock low time (4.7 uS) */
        !           162:        }
        !           163:
        !           164:        DIR(INPUT);
        !           165:
        !           166:        SET(SDA      );
        !           167:        delay(5);
        !           168:        SET(SDA | SCL);
        !           169:        delay(4);
        !           170:        error = (READ & SDA) ? EIO : 0;
        !           171:        SET(SDA      );
        !           172:        delay(5);
        !           173:
        !           174:        if (flags & I2C_F_STOP)
        !           175:                (void) i2c_bitbang_send_stop(v, flags, ops);
        !           176:
        !           177:        return (error);
        !           178: }

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