i2c/busses: Add support for Diolan U2C-12 USB-I2C adapter

This patch adds support for the Diolan U2C-12 USB-I2C adapter.
It also updates MAINTAINERS to list the author as maintainer.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

5 files changed, 578 insertions, 0 deletions

diff --git a/Documentation/i2c/busses/i2c-diolan-u2c b/Documentation/i2c/busses/i2c-diolan-u2c
new file mode 100644
index 000000000000..30fe4bb9a069
--- /dev/null
+++ b/Documentation/i2c/busses/i2c-diolan-u2c
@@ -0,0 +1,26 @@
+Kernel driver i2c-diolan-u2c
+
+Supported adapters:
+  * Diolan U2C-12 I2C-USB adapter
+    Documentation:
+	http://www.diolan.com/i2c/u2c12.html
+
+Author: Guenter Roeck <guenter.roeck@ericsson.com>
+
+Description
+-----------
+
+This is the driver for the Diolan U2C-12 USB-I2C adapter.
+
+The Diolan U2C-12 I2C-USB Adapter provides a low cost solution to connect
+a computer to I2C slave devices using a USB interface. It also supports
+connectivity to SPI devices.
+
+This driver only supports the I2C interface of U2C-12. The driver does not use
+interrupts.
+
+
+Module parameters
+-----------------
+
+* frequency: I2C bus frequency
diff --git a/MAINTAINERS b/MAINTAINERS
index cf0f3a5c09cc..74cad4fa5ae5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2093,6 +2093,12 @@ F:	Documentation/serial/digiepca.txt
 F:	drivers/char/epca*
 F:	drivers/char/digi*
 
+DIOLAN U2C-12 I2C DRIVER
+M:	Guenter Roeck <guenter.roeck@ericsson.com>
+L:	linux-i2c@vger.kernel.org
+S:	Maintained
+F:	drivers/i2c/busses/i2c-diolan-u2c.c
+
 DIRECTORY NOTIFICATION (DNOTIFY)
 M:	Eric Paris <eparis@parisplace.org>
 S:	Maintained
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 113505a6434e..30f8dbd7e03d 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -648,6 +648,16 @@ config I2C_EG20T
 
 comment "External I2C/SMBus adapter drivers"
 
+config I2C_DIOLAN_U2C
+	tristate "Diolan U2C-12 USB adapter"
+	depends on USB
+	help
+	  If you say yes to this option, support will be included for Diolan
+	  U2C-12, a USB to I2C interface.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-diolan-u2c.
+
 config I2C_PARPORT
 	tristate "Parallel port adapter"
 	depends on PARPORT
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 9d2d0ec7fb23..3c630b7c5663 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -64,6 +64,7 @@ obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
 obj-$(CONFIG_I2C_EG20T)         += i2c-eg20t.o
 
 # External I2C/SMBus adapter drivers
+obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
 obj-$(CONFIG_I2C_PARPORT)	+= i2c-parport.o
 obj-$(CONFIG_I2C_PARPORT_LIGHT)	+= i2c-parport-light.o
 obj-$(CONFIG_I2C_TAOS_EVM)	+= i2c-taos-evm.o
diff --git a/drivers/i2c/busses/i2c-diolan-u2c.c b/drivers/i2c/busses/i2c-diolan-u2c.c
new file mode 100644
index 000000000000..76366716a854
--- /dev/null
+++ b/drivers/i2c/busses/i2c-diolan-u2c.c
@@ -0,0 +1,535 @@
+/*
+ * Driver for the Diolan u2c-12 USB-I2C adapter
+ *
+ * Copyright (c) 2010-2011 Ericsson AB
+ *
+ * Derived from:
+ *  i2c-tiny-usb.c
+ *  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 <linux/types.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+
+#define DRIVER_NAME		"i2c-diolan-u2c"
+
+#define USB_VENDOR_ID_DIOLAN		0x0abf
+#define USB_DEVICE_ID_DIOLAN_U2C	0x3370
+
+#define DIOLAN_OUT_EP		0x02
+#define DIOLAN_IN_EP		0x84
+
+/* commands via USB, must match command ids in the firmware */
+#define CMD_I2C_READ		0x01
+#define CMD_I2C_WRITE		0x02
+#define CMD_I2C_SCAN		0x03	/* Returns list of detected devices */
+#define CMD_I2C_RELEASE_SDA	0x04
+#define CMD_I2C_RELEASE_SCL	0x05
+#define CMD_I2C_DROP_SDA	0x06
+#define CMD_I2C_DROP_SCL	0x07
+#define CMD_I2C_READ_SDA	0x08
+#define CMD_I2C_READ_SCL	0x09
+#define CMD_GET_FW_VERSION	0x0a
+#define CMD_GET_SERIAL		0x0b
+#define CMD_I2C_START		0x0c
+#define CMD_I2C_STOP		0x0d
+#define CMD_I2C_REPEATED_START	0x0e
+#define CMD_I2C_PUT_BYTE	0x0f
+#define CMD_I2C_GET_BYTE	0x10
+#define CMD_I2C_PUT_ACK		0x11
+#define CMD_I2C_GET_ACK		0x12
+#define CMD_I2C_PUT_BYTE_ACK	0x13
+#define CMD_I2C_GET_BYTE_ACK	0x14
+#define CMD_I2C_SET_SPEED	0x1b
+#define CMD_I2C_GET_SPEED	0x1c
+#define CMD_I2C_SET_CLK_SYNC	0x24
+#define CMD_I2C_GET_CLK_SYNC	0x25
+#define CMD_I2C_SET_CLK_SYNC_TO	0x26
+#define CMD_I2C_GET_CLK_SYNC_TO	0x27
+
+#define RESP_OK			0x00
+#define RESP_FAILED		0x01
+#define RESP_BAD_MEMADDR	0x04
+#define RESP_DATA_ERR		0x05
+#define RESP_NOT_IMPLEMENTED	0x06
+#define RESP_NACK		0x07
+#define RESP_TIMEOUT		0x09
+
+#define U2C_I2C_SPEED_FAST	0	/* 400 kHz */
+#define U2C_I2C_SPEED_STD	1	/* 100 kHz */
+#define U2C_I2C_SPEED_2KHZ	242	/* 2 kHz, minimum speed */
+#define U2C_I2C_SPEED(f)	((DIV_ROUND_UP(1000000, (f)) - 10) / 2 + 1)
+
+#define U2C_I2C_FREQ_FAST	400000
+#define U2C_I2C_FREQ_STD	100000
+#define U2C_I2C_FREQ(s)		(1000000 / (2 * (s - 1) + 10))
+
+#define DIOLAN_USB_TIMEOUT	100	/* in ms */
+#define DIOLAN_SYNC_TIMEOUT	20	/* in ms */
+
+#define DIOLAN_OUTBUF_LEN	128
+#define DIOLAN_FLUSH_LEN	(DIOLAN_OUTBUF_LEN - 4)
+#define DIOLAN_INBUF_LEN	256	/* Maximum supported receive length */
+
+/* Structure to hold all of our device specific stuff */
+struct i2c_diolan_u2c {
+	u8 obuffer[DIOLAN_OUTBUF_LEN];	/* output buffer */
+	u8 ibuffer[DIOLAN_INBUF_LEN];	/* input buffer */
+	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 */
+	int olen;			/* Output buffer length */
+	int ocount;			/* Number of enqueued messages */
+};
+
+static uint frequency = U2C_I2C_FREQ_STD;	/* I2C clock frequency in Hz */
+
+module_param(frequency, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(frequency, "I2C clock frequency in hertz");
+
+/* usb layer */
+
+/* Send command to device, and get response. */
+static int diolan_usb_transfer(struct i2c_diolan_u2c *dev)
+{
+	int ret = 0;
+	int actual;
+	int i;
+
+	if (!dev->olen || !dev->ocount)
+		return -EINVAL;
+
+	ret = usb_bulk_msg(dev->usb_dev,
+			   usb_sndbulkpipe(dev->usb_dev, DIOLAN_OUT_EP),
+			   dev->obuffer, dev->olen, &actual,
+			   DIOLAN_USB_TIMEOUT);
+	if (!ret) {
+		for (i = 0; i < dev->ocount; i++) {
+			int tmpret;
+
+			tmpret = usb_bulk_msg(dev->usb_dev,
+					      usb_rcvbulkpipe(dev->usb_dev,
+							      DIOLAN_IN_EP),
+					      dev->ibuffer,
+					      sizeof(dev->ibuffer), &actual,
+					      DIOLAN_USB_TIMEOUT);
+			/*
+			 * Stop command processing if a previous command
+			 * returned an error.
+			 * Note that we still need to retrieve all messages.
+			 */
+			if (ret < 0)
+				continue;
+			ret = tmpret;
+			if (ret == 0 && actual > 0) {
+				switch (dev->ibuffer[actual - 1]) {
+				case RESP_NACK:
+					/*
+					 * Return ENXIO if NACK was received as
+					 * response to the address phase,
+					 * EIO otherwise
+					 */
+					ret = i == 1 ? -ENXIO : -EIO;
+					break;
+				case RESP_TIMEOUT:
+					ret = -ETIMEDOUT;
+					break;
+				case RESP_OK:
+					/* strip off return code */
+					ret = actual - 1;
+					break;
+				default:
+					ret = -EIO;
+					break;
+				}
+			}
+		}
+	}
+	dev->olen = 0;
+	dev->ocount = 0;
+	return ret;
+}
+
+static int diolan_write_cmd(struct i2c_diolan_u2c *dev, bool flush)
+{
+	if (flush || dev->olen >= DIOLAN_FLUSH_LEN)
+		return diolan_usb_transfer(dev);
+	return 0;
+}
+
+/* Send command (no data) */
+static int diolan_usb_cmd(struct i2c_diolan_u2c *dev, u8 command, bool flush)
+{
+	dev->obuffer[dev->olen++] = command;
+	dev->ocount++;
+	return diolan_write_cmd(dev, flush);
+}
+
+/* Send command with one byte of data */
+static int diolan_usb_cmd_data(struct i2c_diolan_u2c *dev, u8 command, u8 data,
+			       bool flush)
+{
+	dev->obuffer[dev->olen++] = command;
+	dev->obuffer[dev->olen++] = data;
+	dev->ocount++;
+	return diolan_write_cmd(dev, flush);
+}
+
+/* Send command with two bytes of data */
+static int diolan_usb_cmd_data2(struct i2c_diolan_u2c *dev, u8 command, u8 d1,
+				u8 d2, bool flush)
+{
+	dev->obuffer[dev->olen++] = command;
+	dev->obuffer[dev->olen++] = d1;
+	dev->obuffer[dev->olen++] = d2;
+	dev->ocount++;
+	return diolan_write_cmd(dev, flush);
+}
+
+/*
+ * Flush input queue.
+ * If we don't do this at startup and the controller has queued up
+ * messages which were not retrieved, it will stop responding
+ * at some point.
+ */
+static void diolan_flush_input(struct i2c_diolan_u2c *dev)
+{
+	int i;
+
+	for (i = 0; i < 10; i++) {
+		int actual = 0;
+		int ret;
+
+		ret = usb_bulk_msg(dev->usb_dev,
+				   usb_rcvbulkpipe(dev->usb_dev, DIOLAN_IN_EP),
+				   dev->ibuffer, sizeof(dev->ibuffer), &actual,
+				   DIOLAN_USB_TIMEOUT);
+		if (ret < 0 || actual == 0)
+			break;
+	}
+	if (i == 10)
+		dev_err(&dev->interface->dev, "Failed to flush input buffer\n");
+}
+
+static int diolan_i2c_start(struct i2c_diolan_u2c *dev)
+{
+	return diolan_usb_cmd(dev, CMD_I2C_START, false);
+}
+
+static int diolan_i2c_repeated_start(struct i2c_diolan_u2c *dev)
+{
+	return diolan_usb_cmd(dev, CMD_I2C_REPEATED_START, false);
+}
+
+static int diolan_i2c_stop(struct i2c_diolan_u2c *dev)
+{
+	return diolan_usb_cmd(dev, CMD_I2C_STOP, true);
+}
+
+static int diolan_i2c_get_byte_ack(struct i2c_diolan_u2c *dev, bool ack,
+				   u8 *byte)
+{
+	int ret;
+
+	ret = diolan_usb_cmd_data(dev, CMD_I2C_GET_BYTE_ACK, ack, true);
+	if (ret > 0)
+		*byte = dev->ibuffer[0];
+	else if (ret == 0)
+		ret = -EIO;
+
+	return ret;
+}
+
+static int diolan_i2c_put_byte_ack(struct i2c_diolan_u2c *dev, u8 byte)
+{
+	return diolan_usb_cmd_data(dev, CMD_I2C_PUT_BYTE_ACK, byte, false);
+}
+
+static int diolan_set_speed(struct i2c_diolan_u2c *dev, u8 speed)
+{
+	return diolan_usb_cmd_data(dev, CMD_I2C_SET_SPEED, speed, true);
+}
+
+/* Enable or disable clock synchronization (stretching) */
+static int diolan_set_clock_synch(struct i2c_diolan_u2c *dev, bool enable)
+{
+	return diolan_usb_cmd_data(dev, CMD_I2C_SET_CLK_SYNC, enable, true);
+}
+
+/* Set clock synchronization timeout in ms */
+static int diolan_set_clock_synch_timeout(struct i2c_diolan_u2c *dev, int ms)
+{
+	int to_val = ms * 10;
+
+	return diolan_usb_cmd_data2(dev, CMD_I2C_SET_CLK_SYNC_TO,
+				    to_val & 0xff, (to_val >> 8) & 0xff, true);
+}
+
+static void diolan_fw_version(struct i2c_diolan_u2c *dev)
+{
+	int ret;
+
+	ret = diolan_usb_cmd(dev, CMD_GET_FW_VERSION, true);
+	if (ret >= 2)
+		dev_info(&dev->interface->dev,
+			 "Diolan U2C firmware version %u.%u\n",
+			 (unsigned int)dev->ibuffer[0],
+			 (unsigned int)dev->ibuffer[1]);
+}
+
+static void diolan_get_serial(struct i2c_diolan_u2c *dev)
+{
+	int ret;
+	u32 serial;
+
+	ret = diolan_usb_cmd(dev, CMD_GET_SERIAL, true);
+	if (ret >= 4) {
+		serial = le32_to_cpu(*(u32 *)dev->ibuffer);
+		dev_info(&dev->interface->dev,
+			 "Diolan U2C serial number %u\n", serial);
+	}
+}
+
+static int diolan_init(struct i2c_diolan_u2c *dev)
+{
+	int speed, ret;
+
+	if (frequency >= 200000) {
+		speed = U2C_I2C_SPEED_FAST;
+		frequency = U2C_I2C_FREQ_FAST;
+	} else if (frequency >= 100000 || frequency == 0) {
+		speed = U2C_I2C_SPEED_STD;
+		frequency = U2C_I2C_FREQ_STD;
+	} else {
+		speed = U2C_I2C_SPEED(frequency);
+		if (speed > U2C_I2C_SPEED_2KHZ)
+			speed = U2C_I2C_SPEED_2KHZ;
+		frequency = U2C_I2C_FREQ(speed);
+	}
+
+	dev_info(&dev->interface->dev,
+		 "Diolan U2C at USB bus %03d address %03d speed %d Hz\n",
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum, frequency);
+
+	diolan_flush_input(dev);
+	diolan_fw_version(dev);
+	diolan_get_serial(dev);
+
+	/* Set I2C speed */
+	ret = diolan_set_speed(dev, speed);
+	if (ret < 0)
+		return ret;
+
+	/* Configure I2C clock synchronization */
+	ret = diolan_set_clock_synch(dev, speed != U2C_I2C_SPEED_FAST);
+	if (ret < 0)
+		return ret;
+
+	if (speed != U2C_I2C_SPEED_FAST)
+		ret = diolan_set_clock_synch_timeout(dev, DIOLAN_SYNC_TIMEOUT);
+
+	return ret;
+}
+
+/* i2c layer */
+
+static int diolan_usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
+			   int num)
+{
+	struct i2c_diolan_u2c *dev = i2c_get_adapdata(adapter);
+	struct i2c_msg *pmsg;
+	int i, j;
+	int ret, sret;
+
+	ret = diolan_i2c_start(dev);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < num; i++) {
+		pmsg = &msgs[i];
+		if (i) {
+			ret = diolan_i2c_repeated_start(dev);
+			if (ret < 0)
+				goto abort;
+		}
+		if (pmsg->flags & I2C_M_RD) {
+			ret =
+			    diolan_i2c_put_byte_ack(dev, (pmsg->addr << 1) | 1);
+			if (ret < 0)
+				goto abort;
+			for (j = 0; j < pmsg->len; j++) {
+				u8 byte;
+				bool ack = j < pmsg->len - 1;
+
+				/*
+				 * Don't send NACK if this is the first byte
+				 * of a SMBUS_BLOCK message.
+				 */
+				if (j == 0 && (pmsg->flags & I2C_M_RECV_LEN))
+					ack = true;
+
+				ret = diolan_i2c_get_byte_ack(dev, ack, &byte);
+				if (ret < 0)
+					goto abort;
+				/*
+				 * Adjust count if first received byte is length
+				 */
+				if (j == 0 && (pmsg->flags & I2C_M_RECV_LEN)) {
+					if (byte == 0
+					    || byte > I2C_SMBUS_BLOCK_MAX) {
+						ret = -EPROTO;
+						goto abort;
+					}
+					pmsg->len += byte;
+				}
+				pmsg->buf[j] = byte;
+			}
+		} else {
+			ret = diolan_i2c_put_byte_ack(dev, pmsg->addr << 1);
+			if (ret < 0)
+				goto abort;
+			for (j = 0; j < pmsg->len; j++) {
+				ret = diolan_i2c_put_byte_ack(dev,
+							      pmsg->buf[j]);
+				if (ret < 0)
+					goto abort;
+			}
+		}
+	}
+abort:
+	sret = diolan_i2c_stop(dev);
+	if (sret < 0 && ret >= 0)
+		ret = sret;
+	return ret;
+}
+
+/*
+ * Return list of supported functionality.
+ */
+static u32 diolan_usb_func(struct i2c_adapter *a)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+	       I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL;
+}
+
+static const struct i2c_algorithm diolan_usb_algorithm = {
+	.master_xfer = diolan_usb_xfer,
+	.functionality = diolan_usb_func,
+};
+
+/* device layer */
+
+static const struct usb_device_id diolan_u2c_table[] = {
+	{ USB_DEVICE(USB_VENDOR_ID_DIOLAN, USB_DEVICE_ID_DIOLAN_U2C) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, diolan_u2c_table);
+
+static void diolan_u2c_free(struct i2c_diolan_u2c *dev)
+{
+	usb_put_dev(dev->usb_dev);
+	kfree(dev);
+}
+
+static int diolan_u2c_probe(struct usb_interface *interface,
+			    const struct usb_device_id *id)
+{
+	struct i2c_diolan_u2c *dev;
+	int ret;
+
+	/* allocate memory for our device state and initialize it */
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL) {
+		dev_err(&interface->dev, "no memory for device state\n");
+		ret = -ENOMEM;
+		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);
+
+	/* setup i2c adapter description */
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_HWMON;
+	dev->adapter.algo = &diolan_usb_algorithm;
+	i2c_set_adapdata(&dev->adapter, dev);
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
+		 DRIVER_NAME " at bus %03d device %03d",
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
+
+	dev->adapter.dev.parent = &dev->interface->dev;
+
+	/* initialize diolan i2c interface */
+	ret = diolan_init(dev);
+	if (ret < 0) {
+		dev_err(&interface->dev, "failed to initialize adapter\n");
+		goto error_free;
+	}
+
+	/* and finally attach to i2c layer */
+	ret = i2c_add_adapter(&dev->adapter);
+	if (ret < 0) {
+		dev_err(&interface->dev, "failed to add I2C adapter\n");
+		goto error_free;
+	}
+
+	dev_dbg(&interface->dev, "connected " DRIVER_NAME "\n");
+
+	return 0;
+
+error_free:
+	usb_set_intfdata(interface, NULL);
+	diolan_u2c_free(dev);
+error:
+	return ret;
+}
+
+static void diolan_u2c_disconnect(struct usb_interface *interface)
+{
+	struct i2c_diolan_u2c *dev = usb_get_intfdata(interface);
+
+	i2c_del_adapter(&dev->adapter);
+	usb_set_intfdata(interface, NULL);
+	diolan_u2c_free(dev);
+
+	dev_dbg(&interface->dev, "disconnected\n");
+}
+
+static struct usb_driver diolan_u2c_driver = {
+	.name = DRIVER_NAME,
+	.probe = diolan_u2c_probe,
+	.disconnect = diolan_u2c_disconnect,
+	.id_table = diolan_u2c_table,
+};
+
+static int __init diolan_u2c_init(void)
+{
+	/* register this driver with the USB subsystem */
+	return usb_register(&diolan_u2c_driver);
+}
+
+static void __exit diolan_u2c_exit(void)
+{
+	/* deregister this driver with the USB subsystem */
+	usb_deregister(&diolan_u2c_driver);
+}
+
+module_init(diolan_u2c_init);
+module_exit(diolan_u2c_exit);
+
+MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
+MODULE_DESCRIPTION(DRIVER_NAME " driver");
+MODULE_LICENSE("GPL");