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>

3 files changed, 289 insertions, 0 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e4f1a463f41a..838dc1c19d61 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/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
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 3a020ea8edef..14d1432f698b 100644
--- a/drivers/i2c/busses/Makefile
+++ b/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
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
new file mode 100644
index 000000000000..907999049d50
--- /dev/null
+++ b/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");