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 $
27 * $DragonFly: src/sys/bus/iicbus/iicbb.c,v 1.5 2006/12/22 23:12:16 swildner Exp $
32 * Generic I2C bit-banging code
42 * From Linux I2C generic interface
43 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
45 * TODO: port Peter's generic bit-banging code <dufault@hda.com>
48 #include <sys/param.h>
49 #include <sys/kernel.h>
50 #include <sys/systm.h>
51 #include <sys/module.h>
56 #include <sys/malloc.h>
58 #include <machine/clock.h>
63 #include <bus/smbus/smbconf.h>
65 #include "iicbus_if.h"
72 static int iicbb_attach(device_t);
73 static void iicbb_child_detached(device_t, device_t);
74 static int iicbb_detach(device_t);
75 static int iicbb_print_child(device_t, device_t);
76 static int iicbb_probe(device_t);
78 static int iicbb_callback(device_t, int, caddr_t);
79 static int iicbb_start(device_t, u_char, int);
80 static int iicbb_stop(device_t);
81 static int iicbb_write(device_t, const char *, int, int *, int);
82 static int iicbb_read(device_t, char *, int, int *, int, int);
83 static int iicbb_reset(device_t, u_char, u_char, u_char *);
85 static device_method_t iicbb_methods[] = {
86 /* device interface */
87 DEVMETHOD(device_probe, iicbb_probe),
88 DEVMETHOD(device_attach, iicbb_attach),
89 DEVMETHOD(device_detach, iicbb_detach),
92 DEVMETHOD(bus_child_detached, iicbb_child_detached),
93 DEVMETHOD(bus_print_child, iicbb_print_child),
95 /* iicbus interface */
96 DEVMETHOD(iicbus_callback, iicbb_callback),
97 DEVMETHOD(iicbus_start, iicbb_start),
98 DEVMETHOD(iicbus_repeated_start, iicbb_start),
99 DEVMETHOD(iicbus_stop, iicbb_stop),
100 DEVMETHOD(iicbus_write, iicbb_write),
101 DEVMETHOD(iicbus_read, iicbb_read),
102 DEVMETHOD(iicbus_reset, iicbb_reset),
107 static driver_t iicbb_driver = {
110 sizeof(struct iicbb_softc),
113 static devclass_t iicbb_devclass;
116 iicbb_probe(device_t dev)
118 device_set_desc(dev, "I2C bit-banging driver");
124 iicbb_attach(device_t dev)
126 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
128 sc->iicbus = device_add_child(dev, "iicbus", -1);
131 bus_generic_attach(dev);
137 iicbb_detach(device_t dev)
139 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
143 * We need to save child because the detach indirectly causes
144 * sc->iicbus to be zeroed. Since we added the device
145 * unconditionally in iicbb_attach, we need to make sure we
146 * delete it here. See iicbb_child_detached. We need that
147 * callback in case newbus detached our children w/o detaching
148 * us (say iicbus is a module and unloaded w/o iicbb being
152 bus_generic_detach(dev);
154 device_delete_child(dev, child);
160 iicbb_child_detached(device_t dev, device_t child)
162 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
164 if (child == sc->iicbus)
169 iicbb_print_child(device_t bus, device_t dev)
175 retval += bus_print_child_header(bus, dev);
176 /* retrieve the interface I2C address */
177 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
178 if (error == IIC_ENOADDR) {
179 retval += kprintf(" on %s master-only\n",
180 device_get_nameunit(bus));
182 /* restore the address */
183 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
185 retval += kprintf(" on %s addr 0x%x\n",
186 device_get_nameunit(bus), oldaddr & 0xff);
192 #define I2C_SET(dev,ctrl,data) \
193 IICBB_SETLINES(device_get_parent(dev), ctrl, data)
195 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
197 static int i2c_debug = 0;
198 #define I2C_DEBUG(x) if (i2c_debug) (x)
201 iicbb_one(device_t dev)
210 iicbb_zero(device_t dev)
219 * Waiting for ACKNOWLEDGE.
221 * When a chip is being addressed or has received data it will issue an
222 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
223 * (set it to high level) and then release the CLOCK line.
224 * Now it must wait for the SLAVE to pull the DATA line low.
225 * Actually on the bus this looks like a START condition so nothing happens
226 * because of the fact that the IC's that have not been addressed are doing
229 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
230 * line low and then the SLAVE will release the SDA (data) line.
233 iicbb_ack(device_t dev, int timeout)
242 noack = I2C_GET(dev);
245 DELAY(10); /* XXX wait 10us */
249 I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
255 iicbb_sendbyte(device_t dev, u_char data)
261 (data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
262 I2C_DEBUG(kprintf("w%02x",(int)data));
267 iicbb_readbyte(device_t dev, int last)
270 unsigned char data=0;
280 last ? iicbb_one(dev) : iicbb_zero(dev);
281 I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
286 iicbb_callback(device_t dev, int index, caddr_t data)
288 return (IICBB_CALLBACK(device_get_parent(dev), index, data));
292 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
294 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
298 iicbb_start(device_t dev, u_char slave, int timeout)
302 I2C_DEBUG(kprintf("<"));
310 iicbb_sendbyte(dev, slave);
313 if (iicbb_ack(dev, timeout)) {
326 iicbb_stop(device_t dev)
331 I2C_DEBUG(kprintf(">"));
336 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
338 int bytes, error = 0;
343 iicbb_sendbyte(dev,(u_char)*buf++);
346 if (iicbb_ack(dev, timeout)) {
360 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
366 /* XXX should insert delay here */
367 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
377 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
378 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
379 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);