i2c: New i2c-tiny-usb bus driver

Add a driver for the i2c-tiny-usb interface. This is a simple
do-it-yourself USB to I2C interface targeted at experimental and
home use. See the i2c-tiny-usb homepage for hardware details:
http://www.harbaum.org/till/i2c_tiny_usb

Signed-off-by: Till Harbaum <till@harbaum.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

MAINTAINERS

@@ -1643,6 +1643,13 @@ L:	i2c@lm-sensors.org
 T:	quilt http://khali.linux-fr.org/devel/linux-2.6/jdelvare-i2c/
 S:	Maintained
 
+I2C-TINY-USB DRIVER
+P:	Till Harbaum
+M:	till@harbaum.org
+L:	i2c@lm-sensors.org
+T:	http://www.harbaum.org/till/i2c_tiny_usb
+S:	Maintained
+
 i386 BOOT CODE
 P:	Riley H. Williams
 M:	Riley@Williams.Name

drivers/i2c/busses/Kconfig

@@ -525,6 +525,17 @@ config I2C_STUB
 
 	  If you don't know what to do here, definitely say N.
 
+config I2C_TINY_USB
+	tristate "I2C-Tiny-USB"
+	depends on USB
+	help
+	  If you say yes to this option, support will be included for the
+	  i2c-tiny-usb, a simple do-it-yourself USB to I2C interface. See
+	  http://www.harbaum.org/till/i2c_tiny_usb for hardware details.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-tiny-usb.
+
 config I2C_VERSATILE
 	tristate "ARM Versatile/Realview I2C bus support"
 	depends on ARCH_VERSATILE || ARCH_REALVIEW

drivers/i2c/busses/Makefile

@@ -44,6 +44,7 @@ obj-$(CONFIG_I2C_SIS5595)	+= i2c-sis5595.o
 obj-$(CONFIG_I2C_SIS630)	+= i2c-sis630.o
 obj-$(CONFIG_I2C_SIS96X)	+= i2c-sis96x.o
 obj-$(CONFIG_I2C_STUB)		+= i2c-stub.o
+obj-$(CONFIG_I2C_TINY_USB)	+= i2c-tiny-usb.o
 obj-$(CONFIG_I2C_VERSATILE)	+= i2c-versatile.o
 obj-$(CONFIG_I2C_ACORN)		+= i2c-acorn.o
 obj-$(CONFIG_I2C_VIA)		+= i2c-via.o

drivers/i2c/busses/i2c-tiny-usb.c

@@ -0,0 +1,277 @@
+/*
+ * driver for the i2c-tiny-usb adapter - 1.0
+ * http://www.harbaum.org/till/i2c_tiny_usb
+ *
+ * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+
+/* include interfaces to usb layer */
+#include <linux/usb.h>
+
+/* include interface to i2c layer */
+#include <linux/i2c.h>
+
+/* commands via USB, must match command ids in the firmware */
+#define CMD_ECHO		0
+#define CMD_GET_FUNC		1
+#define CMD_SET_DELAY		2
+#define CMD_GET_STATUS		3
+
+#define CMD_I2C_IO		4
+#define CMD_I2C_IO_BEGIN	(1<<0)
+#define CMD_I2C_IO_END		(1<<1)
+
+/* i2c bit delay, default is 10us -> 100kHz */
+static int delay = 10;
+module_param(delay, int, 0);
+MODULE_PARM_DESC(delay, "bit delay in microseconds, "
+		 "e.g. 10 for 100kHz (default is 100kHz)");
+
+static int usb_read(struct i2c_adapter *adapter, int cmd,
+		    int value, int index, void *data, int len);
+
+static int usb_write(struct i2c_adapter *adapter, int cmd,
+		     int value, int index, void *data, int len);
+
+/* ----- begin of i2c layer ---------------------------------------------- */
+
+#define STATUS_IDLE		0
+#define STATUS_ADDRESS_ACK	1
+#define STATUS_ADDRESS_NAK	2
+
+static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
+{
+	unsigned char status;
+	struct i2c_msg *pmsg;
+	int i;
+
+	dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
+
+	for (i = 0 ; i < num ; i++) {
+		int cmd = CMD_I2C_IO;
+
+		if (i == 0)
+			cmd |= CMD_I2C_IO_BEGIN;
+
+		if (i == num-1)
+			cmd |= CMD_I2C_IO_END;
+
+		pmsg = &msgs[i];
+
+		dev_dbg(&adapter->dev,
+			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
+			i, pmsg->flags & I2C_M_RD ? "read" : "write",
+			pmsg->flags, pmsg->len, pmsg->addr);
+
+		/* and directly send the message */
+		if (pmsg->flags & I2C_M_RD) {
+			/* read data */
+			if (usb_read(adapter, cmd,
+				     pmsg->flags, pmsg->addr,
+				     pmsg->buf, pmsg->len) != pmsg->len) {
+				dev_err(&adapter->dev,
+					"failure reading data\n");
+				return -EREMOTEIO;
+			}
+		} else {
+			/* write data */
+			if (usb_write(adapter, cmd,
+				      pmsg->flags, pmsg->addr,
+				      pmsg->buf, pmsg->len) != pmsg->len) {
+				dev_err(&adapter->dev,
+					"failure writing data\n");
+				return -EREMOTEIO;
+			}
+		}
+
+		/* read status */
+		if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
+			dev_err(&adapter->dev, "failure reading status\n");
+			return -EREMOTEIO;
+		}
+
+		dev_dbg(&adapter->dev, "  status = %d\n", status);
+		if (status == STATUS_ADDRESS_NAK)
+			return -EREMOTEIO;
+	}
+
+	return i;
+}
+
+static u32 usb_func(struct i2c_adapter *adapter)
+{
+	u32 func;
+
+	/* get functionality from adapter */
+	if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
+	    sizeof(func)) {
+		dev_err(&adapter->dev, "failure reading functionality\n");
+		return 0;
+	}
+
+	return func;
+}
+
+/* This is the actual algorithm we define */
+static const struct i2c_algorithm usb_algorithm = {
+	.master_xfer	= usb_xfer,
+	.functionality	= usb_func,
+};
+
+/* ----- end of i2c layer ------------------------------------------------ */
+
+/* ----- begin of usb layer ---------------------------------------------- */
+
+/* The usb i2c interface uses a vid/pid pair donated by */
+/* Future Technology Devices International Ltd. */
+static struct usb_device_id i2c_tiny_usb_table [] = {
+	{ USB_DEVICE(0x0403, 0xc631) },
+	{ }			/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
+
+/* Structure to hold all of our device specific stuff */
+struct i2c_tiny_usb {
+	struct usb_device *usb_dev; /* the usb device for this device */
+	struct usb_interface *interface; /* the interface for this device */
+	struct i2c_adapter adapter; /* i2c related things */
+};
+
+static int usb_read(struct i2c_adapter *adapter, int cmd,
+		    int value, int index, void *data, int len)
+{
+	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
+
+	/* do control transfer */
+	return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
+			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
+			       USB_DIR_IN, value, index, data, len, 2000);
+}
+
+static int usb_write(struct i2c_adapter *adapter, int cmd,
+		     int value, int index, void *data, int len)
+{
+	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
+
+	/* do control transfer */
+	return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
+			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
+			       value, index, data, len, 2000);
+}
+
+static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
+{
+	usb_put_dev(dev->usb_dev);
+	kfree(dev);
+}
+
+static int i2c_tiny_usb_probe(struct usb_interface *interface,
+			      const struct usb_device_id *id)
+{
+	struct i2c_tiny_usb *dev;
+	int retval = -ENOMEM;
+	u16 version;
+
+	dev_dbg(&interface->dev, "probing usb device\n");
+
+	/* allocate memory for our device state and initialize it */
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL) {
+		dev_err(&interface->dev, "Out of memory\n");
+		goto error;
+	}
+
+	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
+	dev->interface = interface;
+
+	/* save our data pointer in this interface device */
+	usb_set_intfdata(interface, dev);
+
+	version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
+	dev_info(&interface->dev,
+		 "version %x.%02x found at bus %03d address %03d\n",
+		 version >> 8, version & 0xff,
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
+
+	/* setup i2c adapter description */
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_HWMON;
+	dev->adapter.algo = &usb_algorithm;
+	dev->adapter.algo_data = dev;
+	snprintf(dev->adapter.name, I2C_NAME_SIZE,
+		 "i2c-tiny-usb at bus %03d device %03d",
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
+
+	if (usb_write(&dev->adapter, CMD_SET_DELAY,
+		      cpu_to_le16(delay), 0, NULL, 0) != 0) {
+		dev_err(&dev->adapter.dev,
+			"failure setting delay to %dus\n", delay);
+		retval = -EIO;
+		goto error;
+	}
+
+	dev->adapter.dev.parent = &dev->interface->dev;
+
+	/* and finally attach to i2c layer */
+	i2c_add_adapter(&dev->adapter);
+
+	/* inform user about successful attachment to i2c layer */
+	dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
+
+	return 0;
+
+ error:
+	if (dev)
+		i2c_tiny_usb_free(dev);
+
+	return retval;
+}
+
+static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
+{
+	struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
+
+	i2c_del_adapter(&dev->adapter);
+	usb_set_intfdata(interface, NULL);
+	i2c_tiny_usb_free(dev);
+
+	dev_dbg(&interface->dev, "disconnected\n");
+}
+
+static struct usb_driver i2c_tiny_usb_driver = {
+	.name		= "i2c-tiny-usb",
+	.probe		= i2c_tiny_usb_probe,
+	.disconnect	= i2c_tiny_usb_disconnect,
+	.id_table	= i2c_tiny_usb_table,
+};
+
+static int __init usb_i2c_tiny_usb_init(void)
+{
+	/* register this driver with the USB subsystem */
+	return usb_register(&i2c_tiny_usb_driver);
+}
+
+static void __exit usb_i2c_tiny_usb_exit(void)
+{
+	/* deregister this driver with the USB subsystem */
+	usb_deregister(&i2c_tiny_usb_driver);
+}
+
+module_init(usb_i2c_tiny_usb_init);
+module_exit(usb_i2c_tiny_usb_exit);
+
+/* ----- end of usb layer ------------------------------------------------ */
+
+MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
+MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
+MODULE_LICENSE("GPL");