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");