Put back i2c bit-banging code, we'll need it soon.

1 files changed, 179 insertions, 0 deletions

diff --git a/sys/dev/i2c/i2c_bitbang.c b/sys/dev/i2c/i2c_bitbang.c
new file mode 100644
index 00000000000..5a865b0af9c
--- /dev/null
+++ b/sys/dev/i2c/i2c_bitbang.c
@@ -0,0 +1,179 @@
+/*	$OpenBSD: i2c_bitbang.c,v 1.3 2006/01/13 23:56:46 grange Exp $	*/
+/*	$NetBSD: i2c_bitbang.c,v 1.1 2003/09/30 00:35:31 thorpej Exp $	*/
+
+/*
+ * Copyright (c) 2003 Wasabi Systems, Inc.
+ * All rights reserved.
+ *
+ * Written by Jason R. Thorpe for Wasabi Systems, Inc.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed for the NetBSD Project by
+ *      Wasabi Systems, Inc.
+ * 4. The name of Wasabi Systems, Inc. may not be used to endorse
+ *    or promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
+ * 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.
+ */
+
+/*
+ * Common module for bit-bang'ing an I2C bus.
+ */
+
+#include <sys/param.h>
+
+#include <dev/i2c/i2cvar.h>
+#include <dev/i2c/i2c_bitbang.h>
+
+#define	BB_SET(x)	ops->ibo_set_bits(v, (x))
+#define	BB_DIR(x)	ops->ibo_set_dir(v, (x))
+#define	BB_READ		ops->ibo_read_bits(v)
+
+#define	SDA		ops->ibo_bits[I2C_BIT_SDA]	/* i2c signal */
+#define	SCL		ops->ibo_bits[I2C_BIT_SCL]	/* i2c signal */
+#define	OUTPUT		ops->ibo_bits[I2C_BIT_OUTPUT]	/* SDA is output */
+#define	INPUT		ops->ibo_bits[I2C_BIT_INPUT]	/* SDA is input */
+
+/*ARGSUSED*/
+int
+i2c_bitbang_send_start(void *v, int flags, i2c_bitbang_ops_t ops)
+{
+
+	BB_DIR(OUTPUT);
+
+	BB_SET(SDA | SCL);
+	delay(5);		/* bus free time (4.7 uS) */
+	BB_SET(      SCL);
+	delay(4);		/* start hold time (4.0 uS) */
+	BB_SET(        0);
+	delay(5);		/* clock low time (4.7 uS) */
+
+	return (0);
+}
+
+/*ARGSUSED*/
+int
+i2c_bitbang_send_stop(void *v, int flags, i2c_bitbang_ops_t ops)
+{
+
+	BB_DIR(OUTPUT);
+
+	BB_SET(      SCL);
+	delay(4);		/* stop setup time (4.0 uS) */
+	BB_SET(SDA | SCL);
+
+	return (0);
+}
+
+int
+i2c_bitbang_initiate_xfer(void *v, i2c_addr_t addr, int flags,
+    i2c_bitbang_ops_t ops)
+{
+	int i2caddr;
+
+	/* XXX Only support 7-bit addressing for now. */
+	if ((addr & 0x78) == 0x78)
+		return (EINVAL);
+
+	i2caddr = (addr << 1) | ((flags & I2C_F_READ) ? 1 : 0);
+
+	(void) i2c_bitbang_send_start(v, flags, ops);
+	return (i2c_bitbang_write_byte(v, i2caddr, flags & ~I2C_F_STOP, ops));
+}
+
+int
+i2c_bitbang_read_byte(void *v, uint8_t *valp, int flags,
+    i2c_bitbang_ops_t ops)
+{
+	int i;
+	uint8_t val = 0;
+	uint32_t bit;
+
+	BB_DIR(INPUT);
+	BB_SET(SDA      );
+
+	for (i = 0; i < 8; i++) {
+		val <<= 1;
+		BB_SET(SDA | SCL);
+		delay(4);	/* clock high time (4.0 uS) */
+		if (BB_READ & SDA)
+			val |= 1;
+		BB_SET(SDA      );
+		delay(5);	/* clock low time (4.7 uS) */
+	}
+
+	bit = (flags & I2C_F_LAST) ? SDA : 0;
+	BB_DIR(OUTPUT);
+	BB_SET(bit      );
+	delay(1);	/* data setup time (250 nS) */
+	BB_SET(bit | SCL);
+	delay(4);	/* clock high time (4.0 uS) */
+	BB_SET(bit      );
+	delay(5);	/* clock low time (4.7 uS) */
+
+	BB_DIR(INPUT);
+	BB_SET(SDA      );
+	delay(5);
+
+	if ((flags & (I2C_F_STOP | I2C_F_LAST)) == (I2C_F_STOP | I2C_F_LAST))
+		(void) i2c_bitbang_send_stop(v, flags, ops);
+
+	*valp = val;
+	return (0);
+}
+
+int
+i2c_bitbang_write_byte(void *v, uint8_t val, int flags,
+    i2c_bitbang_ops_t ops)
+{
+	uint32_t bit;
+	uint8_t mask;
+	int error;
+
+	BB_DIR(OUTPUT);
+
+	for (mask = 0x80; mask != 0; mask >>= 1) {
+		bit = (val & mask) ? SDA : 0;
+		BB_SET(bit      );
+		delay(1);	/* data setup time (250 nS) */
+		BB_SET(bit | SCL);
+		delay(4);	/* clock high time (4.0 uS) */
+		BB_SET(bit      );
+		delay(5);	/* clock low time (4.7 uS) */
+	}
+
+	BB_DIR(INPUT);
+
+	BB_SET(SDA      );
+	delay(5);
+	BB_SET(SDA | SCL);
+	delay(4);
+	error = (BB_READ & SDA) ? EIO : 0;
+	BB_SET(SDA      );
+	delay(5);
+
+	if (flags & I2C_F_STOP)
+		(void) i2c_bitbang_send_stop(v, flags, ops);
+
+	return (error);
+}