iicbb is generic support for I2C bit-banging.

Other files: timeout management added to the I2C framework.

1 files changed, 323 insertions, 0 deletions

diff --git a/sys/dev/iicbus/iicbb.c b/sys/dev/iicbus/iicbb.c
new file mode 100644
index 0000000..f544d4b
--- /dev/null
+++ b/sys/dev/iicbus/iicbb.c
@@ -0,0 +1,323 @@
+/*-
+ * Copyright (c) 1998 Nicolas Souchu
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	$Id$
+ *
+ */
+
+/*
+ * Generic I2C bit-banging code
+ *
+ * Example:
+ *
+ *	iicbus
+ *	 /  \ 
+ *    iicbb pcf
+ *     |  \
+ *   bti2c lpbb
+ *
+ * From Linux I2C generic interface
+ * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
+ *
+ * TODO: port Peter's generic bit-banging code <dufault@hda.com>
+ */
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/systm.h>
+#include <sys/module.h>
+#include <sys/bus.h>
+#include <sys/conf.h>
+#include <sys/buf.h>
+#include <sys/uio.h>
+#include <sys/malloc.h>
+
+#include <machine/clock.h>
+
+#include <dev/iicbus/iiconf.h>
+#include <dev/iicbus/iicbus.h>
+
+#include <dev/smbus/smbconf.h>
+
+#include "iicbus_if.h"
+#include "iicbb_if.h"
+
+struct iicbb_softc {
+	int dummy;
+};
+
+static int iicbb_probe(device_t);
+static int iicbb_attach(device_t);
+static void iicbb_print_child(device_t, device_t);
+
+static int iicbb_callback(device_t, int, caddr_t);
+static int iicbb_start(device_t, u_char, int);
+static int iicbb_stop(device_t);
+static int iicbb_write(device_t, char *, int, int *, int);
+static int iicbb_read(device_t, char *, int, int *, int, int);
+static int iicbb_reset(device_t, u_char, u_char, u_char *);
+
+static device_method_t iicbb_methods[] = {
+	/* device interface */
+	DEVMETHOD(device_probe,		iicbb_probe),
+	DEVMETHOD(device_attach,	iicbb_attach),
+
+	/* bus interface */
+	DEVMETHOD(bus_print_child,	iicbb_print_child),
+
+	/* iicbus interface */
+	DEVMETHOD(iicbus_callback,	iicbb_callback),
+	DEVMETHOD(iicbus_start,		iicbb_start),
+	DEVMETHOD(iicbus_repeated_start, iicbb_start),
+	DEVMETHOD(iicbus_stop,		iicbb_stop),
+	DEVMETHOD(iicbus_write,		iicbb_write),
+	DEVMETHOD(iicbus_read,		iicbb_read),
+	DEVMETHOD(iicbus_reset,		iicbb_reset),
+
+	{ 0, 0 }
+};
+
+static driver_t iicbb_driver = {
+	"iicbb",
+	iicbb_methods,
+	DRIVER_TYPE_MISC,
+	sizeof(struct iicbb_softc),
+};
+
+static devclass_t iicbb_devclass;
+
+static int iicbb_probe(device_t dev)
+{
+	device_set_desc(dev, "I2C generic bit-banging driver");
+
+	return (0);
+}
+
+static int iicbb_attach(device_t dev)
+{
+	return (0);
+}
+
+static void
+iicbb_print_child(device_t bus, device_t dev)
+{
+	int error;
+	u_char oldaddr;
+
+	/* retrieve the interface I2C address */
+	error = IICBB_RESET(bus, IIC_FASTEST, 0, &oldaddr);
+	if (error == IIC_ENOADDR) {
+		printf(" on %s%d master-only", device_get_name(bus),
+			device_get_unit(bus));
+
+	} else {
+		/* restore the address */
+		IICBB_RESET(bus, IIC_FASTEST, oldaddr, NULL);
+
+		printf(" on %s%d addr 0x%x", device_get_name(bus),
+			device_get_unit(bus), oldaddr & 0xff);
+	}
+
+	return;
+}
+
+#define I2C_SET(dev,ctrl,data) \
+	IICBB_SETLINES(device_get_parent(dev), ctrl, data)
+
+#define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
+
+static int i2c_debug = 0;
+#define I2C_DEBUG(x) if (i2c_debug) (x)
+
+static void iicbb_one(device_t dev)
+{
+	I2C_SET(dev,0,1);
+	I2C_SET(dev,1,1);
+	I2C_SET(dev,0,1);
+	return;
+}
+
+static void iicbb_zero(device_t dev)
+{
+	I2C_SET(dev,0,0);
+	I2C_SET(dev,1,0);
+	I2C_SET(dev,0,0);
+	return;
+}
+
+/*
+ * Waiting for ACKNOWLEDGE.
+ *
+ * When a chip is being addressed or has received data it will issue an
+ * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
+ * (set it to high level) and then release the CLOCK line.
+ * Now it must wait for the SLAVE to pull the DATA line low.
+ * Actually on the bus this looks like a START condition so nothing happens
+ * because of the fact that the IC's that have not been addressed are doing
+ * nothing.
+ *
+ * When the SLAVE has pulled this line low the MASTER will take the CLOCK
+ * line low and then the SLAVE will release the SDA (data) line.
+ */
+static int iicbb_ack(device_t dev, int timeout)
+{
+	int noack;
+	int k = timeout/10;
+    
+	I2C_SET(dev,0,1);
+	I2C_SET(dev,1,1);
+
+	do {
+		noack = I2C_GET(dev);
+		if (!noack)
+			break;
+		DELAY(10);		/* XXX wait 10us */
+	} while (k--);
+
+	I2C_SET(dev,0,1);
+	I2C_DEBUG(printf("%c ",noack?'-':'+'));
+
+	return (noack);
+}
+
+static void iicbb_sendbyte(device_t dev, u_char data)
+{
+	int i;
+    
+	I2C_SET(dev,0,0);
+	for (i=7; i>=0; i--)
+		(data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
+	I2C_DEBUG(printf("w%02x",(int)data));
+	return;
+}
+
+static u_char iicbb_readbyte(device_t dev, int last)
+{
+	int i;
+	unsigned char data=0;
+    
+	I2C_SET(dev,0,1);
+	for (i=7; i>=0; i--) 
+	{
+		I2C_SET(dev,1,1);
+		if (I2C_GET(dev))
+			data |= (1<<i);
+		I2C_SET(dev,0,1);
+	}
+	last ? iicbb_one(dev) : iicbb_zero(dev);
+	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
+	return data;
+}
+
+static int iicbb_callback(device_t dev, int index, caddr_t data)
+{
+	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
+}
+
+static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
+{
+	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
+}
+
+static int iicbb_start(device_t dev, u_char slave, int timeout)
+{
+	int error;
+
+	I2C_DEBUG(printf("<"));
+
+	I2C_SET(dev,0,1);
+	I2C_SET(dev,1,1);
+	I2C_SET(dev,1,0);
+	I2C_SET(dev,0,0);
+
+	/* send address */
+	iicbb_sendbyte(dev, slave);
+
+	/* check for ack */
+	if (iicbb_ack(dev, timeout)) {
+		error = IIC_ENOACK;
+		goto error;
+	}
+
+	return(0);
+
+error:
+	iicbb_stop(dev);
+	return (error);
+}
+
+static int iicbb_stop(device_t dev)
+{
+	I2C_SET(dev,0,0);
+	I2C_SET(dev,1,0);
+	I2C_SET(dev,1,1);
+	I2C_DEBUG(printf(">"));
+	return (0);
+}
+
+static int iicbb_write(device_t dev, char * buf, int len, int *sent,
+			int timeout)
+{
+	int bytes, error = 0;
+
+	bytes = 0;
+	while (len) {
+		/* send byte */
+		iicbb_sendbyte(dev,(u_char)*buf++);
+
+		/* check for ack */
+		if (iicbb_ack(dev, timeout)) {
+			error = IIC_ENOACK;
+			goto error;
+		}
+		bytes ++;
+		len --;
+	}
+
+error:
+	*sent = bytes;
+	return (error);
+}
+
+static int iicbb_read(device_t dev, char * buf, int len, int *read,
+			int last, int delay)
+{
+	int bytes;
+
+	bytes = 0;
+	while (len) {
+		/* XXX should insert delay here */
+		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? 1 : 0);
+
+		bytes ++;
+		len --;
+	}
+
+	*read = bytes;
+	return (0);
+}
+
+DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
+DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);