2 * Copyright (c) 1998 Nicolas Souchu
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * $FreeBSD: src/sys/dev/iicbus/iicbb.c,v 1.6.2.2 2002/04/19 05:52:12 nsouch Exp $
31 * Generic I2C bit-banging code
41 * From Linux I2C generic interface
42 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
44 * TODO: port Peter's generic bit-banging code <dufault@hda.com>
47 #include <sys/param.h>
48 #include <sys/kernel.h>
49 #include <sys/systm.h>
50 #include <sys/module.h>
55 #include <sys/malloc.h>
57 #include <machine/clock.h>
59 #include <dev/iicbus/iiconf.h>
60 #include <dev/iicbus/iicbus.h>
62 #include <dev/smbus/smbconf.h>
64 #include "iicbus_if.h"
71 static int iicbb_probe(device_t);
72 static int iicbb_attach(device_t);
73 static int iicbb_detach(device_t);
74 static int iicbb_print_child(device_t, device_t);
76 static int iicbb_callback(device_t, int, caddr_t);
77 static int iicbb_start(device_t, u_char, int);
78 static int iicbb_stop(device_t);
79 static int iicbb_write(device_t, char *, int, int *, int);
80 static int iicbb_read(device_t, char *, int, int *, int, int);
81 static int iicbb_reset(device_t, u_char, u_char, u_char *);
83 static device_method_t iicbb_methods[] = {
84 /* device interface */
85 DEVMETHOD(device_probe, iicbb_probe),
86 DEVMETHOD(device_attach, iicbb_attach),
87 DEVMETHOD(device_detach, iicbb_detach),
90 DEVMETHOD(bus_print_child, iicbb_print_child),
92 /* iicbus interface */
93 DEVMETHOD(iicbus_callback, iicbb_callback),
94 DEVMETHOD(iicbus_start, iicbb_start),
95 DEVMETHOD(iicbus_repeated_start, iicbb_start),
96 DEVMETHOD(iicbus_stop, iicbb_stop),
97 DEVMETHOD(iicbus_write, iicbb_write),
98 DEVMETHOD(iicbus_read, iicbb_read),
99 DEVMETHOD(iicbus_reset, iicbb_reset),
104 static driver_t iicbb_driver = {
107 sizeof(struct iicbb_softc),
110 static devclass_t iicbb_devclass;
112 static int iicbb_probe(device_t dev)
114 device_set_desc(dev, "I2C bit-banging driver");
119 static int iicbb_attach(device_t dev)
121 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
123 bzero(sc, sizeof(struct iicbb_softc));
125 sc->iicbus = device_add_child(dev, "iicbus", -1);
130 bus_generic_attach(dev);
135 static int iicbb_detach(device_t dev)
137 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
140 bus_generic_detach(dev);
141 device_delete_child(dev, sc->iicbus);
148 iicbb_print_child(device_t bus, device_t dev)
154 retval += bus_print_child_header(bus, dev);
155 /* retrieve the interface I2C address */
156 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
157 if (error == IIC_ENOADDR) {
158 retval += printf(" on %s master-only\n",
159 device_get_nameunit(bus));
161 /* restore the address */
162 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
164 retval += printf(" on %s addr 0x%x\n",
165 device_get_nameunit(bus), oldaddr & 0xff);
171 #define I2C_SET(dev,ctrl,data) \
172 IICBB_SETLINES(device_get_parent(dev), ctrl, data)
174 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
176 static int i2c_debug = 0;
177 #define I2C_DEBUG(x) if (i2c_debug) (x)
179 static void iicbb_one(device_t dev)
187 static void iicbb_zero(device_t dev)
196 * Waiting for ACKNOWLEDGE.
198 * When a chip is being addressed or has received data it will issue an
199 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
200 * (set it to high level) and then release the CLOCK line.
201 * Now it must wait for the SLAVE to pull the DATA line low.
202 * Actually on the bus this looks like a START condition so nothing happens
203 * because of the fact that the IC's that have not been addressed are doing
206 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
207 * line low and then the SLAVE will release the SDA (data) line.
209 static int iicbb_ack(device_t dev, int timeout)
218 noack = I2C_GET(dev);
221 DELAY(10); /* XXX wait 10us */
225 I2C_DEBUG(printf("%c ",noack?'-':'+'));
230 static void iicbb_sendbyte(device_t dev, u_char data)
236 (data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
237 I2C_DEBUG(printf("w%02x",(int)data));
241 static u_char iicbb_readbyte(device_t dev, int last)
244 unsigned char data=0;
254 last ? iicbb_one(dev) : iicbb_zero(dev);
255 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
259 static int iicbb_callback(device_t dev, int index, caddr_t data)
261 return (IICBB_CALLBACK(device_get_parent(dev), index, data));
264 static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
266 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
269 static int iicbb_start(device_t dev, u_char slave, int timeout)
273 I2C_DEBUG(printf("<"));
281 iicbb_sendbyte(dev, slave);
284 if (iicbb_ack(dev, timeout)) {
296 static int iicbb_stop(device_t dev)
301 I2C_DEBUG(printf(">"));
305 static int iicbb_write(device_t dev, char * buf, int len, int *sent,
308 int bytes, error = 0;
313 iicbb_sendbyte(dev,(u_char)*buf++);
316 if (iicbb_ack(dev, timeout)) {
329 static int iicbb_read(device_t dev, char * buf, int len, int *read,
336 /* XXX should insert delay here */
337 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
347 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
348 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
349 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);