2 * Copyright (c) 1998, 2001 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 1.21 2009/02/10 22:50:23 imp Exp $
30 * Generic I2C bit-banging code
40 * From Linux I2C generic interface
41 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
45 #include <sys/param.h>
46 #include <sys/kernel.h>
47 #include <sys/systm.h>
48 #include <sys/module.h>
52 #include <bus/iicbus/iiconf.h>
53 #include <bus/iicbus/iicbus.h>
55 #include <bus/smbus/smbconf.h>
57 #include "iicbus_if.h"
64 static int iicbb_attach(device_t);
65 static void iicbb_child_detached(device_t, device_t);
66 static int iicbb_detach(device_t);
67 static int iicbb_print_child(device_t, device_t);
68 static int iicbb_probe(device_t);
70 static int iicbb_callback(device_t, int, caddr_t);
71 static int iicbb_start(device_t, u_char, int);
72 static int iicbb_stop(device_t);
73 static int iicbb_write(device_t, const char *, int, int *, int);
74 static int iicbb_read(device_t, char *, int, int *, int, int);
75 static int iicbb_reset(device_t, u_char, u_char, u_char *);
77 static device_method_t iicbb_methods[] = {
78 /* device interface */
79 DEVMETHOD(device_probe, iicbb_probe),
80 DEVMETHOD(device_attach, iicbb_attach),
81 DEVMETHOD(device_detach, iicbb_detach),
84 DEVMETHOD(bus_child_detached, iicbb_child_detached),
85 DEVMETHOD(bus_print_child, iicbb_print_child),
87 /* iicbus interface */
88 DEVMETHOD(iicbus_callback, iicbb_callback),
89 DEVMETHOD(iicbus_start, iicbb_start),
90 DEVMETHOD(iicbus_repeated_start, iicbb_start),
91 DEVMETHOD(iicbus_stop, iicbb_stop),
92 DEVMETHOD(iicbus_write, iicbb_write),
93 DEVMETHOD(iicbus_read, iicbb_read),
94 DEVMETHOD(iicbus_reset, iicbb_reset),
95 DEVMETHOD(iicbus_transfer, iicbus_transfer_gen),
100 driver_t iicbb_driver = {
103 sizeof(struct iicbb_softc),
106 devclass_t iicbb_devclass;
109 iicbb_probe(device_t dev)
111 device_set_desc(dev, "I2C bit-banging driver");
117 iicbb_attach(device_t dev)
119 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
121 sc->iicbus = device_add_child(dev, "iicbus", -1);
124 bus_generic_attach(dev);
130 iicbb_detach(device_t dev)
132 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
136 * We need to save child because the detach indirectly causes
137 * sc->iicbus to be zeroed. Since we added the device
138 * unconditionally in iicbb_attach, we need to make sure we
139 * delete it here. See iicbb_child_detached. We need that
140 * callback in case newbus detached our children w/o detaching
141 * us (say iicbus is a module and unloaded w/o iicbb being
145 bus_generic_detach(dev);
147 device_delete_child(dev, child);
153 iicbb_child_detached( device_t dev, device_t child )
155 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
157 if (child == sc->iicbus)
162 iicbb_print_child(device_t bus, device_t dev)
168 retval += bus_print_child_header(bus, dev);
169 /* retrieve the interface I2C address */
170 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
171 if (error == IIC_ENOADDR) {
172 retval += kprintf(" on %s master-only\n",
173 device_get_nameunit(bus));
175 /* restore the address */
176 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
178 retval += kprintf(" on %s addr 0x%x\n",
179 device_get_nameunit(bus), oldaddr & 0xff);
187 #define I2C_SETSDA(dev,val) do { \
188 IICBB_SETSDA(device_get_parent(dev), val); \
192 #define I2C_SETSCL(dev,val) do { \
193 iicbb_setscl(dev, val, 100); \
196 #define I2C_SET(dev,ctrl,data) do { \
197 I2C_SETSCL(dev, ctrl); \
198 I2C_SETSDA(dev, data); \
201 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
203 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
205 static int i2c_debug = 0;
206 #define I2C_DEBUG(x) do { \
207 if (i2c_debug) (x); \
210 #define I2C_LOG(format,args...) do { \
211 kprintf(format, args); \
215 iicbb_setscl(device_t dev, int val, int timeout)
219 IICBB_SETSCL(device_get_parent(dev), val);
222 while (val && !I2C_GETSCL(dev) && k++ < timeout) {
223 IICBB_SETSCL(device_get_parent(dev), val);
231 iicbb_one(device_t dev, int timeout)
240 iicbb_zero(device_t dev, int timeout)
249 * Waiting for ACKNOWLEDGE.
251 * When a chip is being addressed or has received data it will issue an
252 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
253 * (set it to high level) and then release the CLOCK line.
254 * Now it must wait for the SLAVE to pull the DATA line low.
255 * Actually on the bus this looks like a START condition so nothing happens
256 * because of the fact that the IC's that have not been addressed are doing
259 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
260 * line low and then the SLAVE will release the SDA (data) line.
263 iicbb_ack(device_t dev, int timeout)
271 noack = I2C_GETSDA(dev);
276 } while (k < timeout);
279 I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
285 iicbb_sendbyte(device_t dev, u_char data, int timeout)
289 for (i=7; i>=0; i--) {
291 iicbb_one(dev, timeout);
293 iicbb_zero(dev, timeout);
296 I2C_DEBUG(kprintf("w%02x",(int)data));
301 iicbb_readbyte(device_t dev, int last, int timeout)
304 unsigned char data=0;
315 iicbb_one(dev, timeout);
317 iicbb_zero(dev, timeout);
319 I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
324 iicbb_callback(device_t dev, int index, caddr_t data)
326 return (IICBB_CALLBACK(device_get_parent(dev), index, data));
330 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
332 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
336 iicbb_start(device_t dev, u_char slave, int timeout)
340 I2C_DEBUG(kprintf("<"));
347 iicbb_sendbyte(dev, slave, timeout);
350 if (iicbb_ack(dev, timeout)) {
363 iicbb_stop(device_t dev)
368 I2C_DEBUG(kprintf(">"));
373 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
375 int bytes, error = 0;
380 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
383 if (iicbb_ack(dev, timeout)) {
397 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
403 /* XXX should insert delay here */
404 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
414 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, NULL, NULL);
415 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, NULL, NULL);
416 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, NULL, NULL);
417 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, NULL, NULL);
419 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
420 MODULE_VERSION(iicbb, IICBB_MODVER);