On Wed, 2011-01-19 at 16:14 -0500, Ben Dooks wrote:
> On Wed, Jan 19, 2011 at 01:26:37PM -0800, Guenter Roeck wrote:
> > Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
> > ---
> > drivers/i2c/busses/Kconfig | 10 +
> > drivers/i2c/busses/Makefile | 1 +
> > drivers/i2c/busses/i2c-diolan-u2c.c | 529 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 540 insertions(+), 0 deletions(-)
> > create mode 100644 drivers/i2c/busses/i2c-diolan-u2c.c
> >
> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> > index 113505a..30f8dbd 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 9d2d0ec..3c630b7 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 0000000..44905ce
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-diolan-u2c.c
> > @@ -0,0 +1,529 @@
> > +/*
> > + * 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@xxxxxxxxxxx)
> > + *
> > + * 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
> > +
>
> might be worth type-defing the commands and responses, but not especially
> important.
>
I think it is useful.
> > +#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_CLOSEST(1000000, (f)) - 10) / 2 + 1)
>
> how about rounding down? surely the speed requested is the maximum?
>
No strong opinion either way. Rounding down would mean rounding up the
speed, though (higher number is lower speed). I'll round it up.
> > +/* Structure to hold all of our device specific stuff */
> > +struct i2c_diolan_u2c {
> > + 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 */
> > + u8 obuffer[DIOLAN_OUTBUF_LEN]; /* output buffer */
> > + u8 ibuffer[DIOLAN_INBUF_LEN]; /* input buffer */
>
> you should cache-line align the buffers to avoid any problems with
> dma-vs-cache, etc.
>
Can you point me to some code doing that ? Or do you mean I should
allocate the buffers separately ?
> > +/* 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);
> > + if (tmpret < 0 && ret == 0)
> > + ret = tmpret;
> > + else if (ret >= 0 && tmpret == 0 && actual > 0) {
> > + switch (dev->ibuffer[actual - 1]) {
> > + case RESP_NACK:
> > + ret = -ENXIO;
> > + break;
> > + case RESP_TIMEOUT:
> > + ret = -ETIMEDOUT;
> > + break;
> > + case RESP_OK:
> > + /* strip off return code */
> > + ret = actual - 1;
> > + break;
> > + default:
> > + ret = -EIO;
> > + break;
> > + }
> > + }
> > + }
> > + }
>
> this looks a little complicated with ret and tmpret.
>
Yes. Problem is that I have to retrieve all messages one by one even if
there was an error. I'll see if I can come up with something better, but
right now I have no idea how to simplify it.
> > + dev->olen = 0;
> > + dev->ocount = 0;
> > + return ret;
> > +}
> > +
>
> > +static int diolan_usb_cmd_data2(struct i2c_diolan_u2c *dev, u8 command, u8 d1,
> > + u8 d2, bool flush)
> > +{
> > + int ret = 0;
> > +
> > + dev->obuffer[dev->olen++] = command;
> > + dev->obuffer[dev->olen++] = d1;
> > + dev->obuffer[dev->olen++] = d2;
> > + dev->ocount++;
> > + if (flush || dev->olen >= DIOLAN_FLUSH_LEN)
> > + ret = diolan_usb_transfer(dev);
> > + return ret;
> > +}
>
> how about wrapping the check for usb_transfer into one call?
> say diolan_written_cmd(dev, flush) and then just use that as a
> return and remove any need for 'int ret = 0' as well.
>
Ok.
> > +/*
> > + * 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");
>
> [snip]
>
>
> > + "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);
>
> why bother returning ret from some of these when they're not checked?
>
Good point. Made it void.
> > + 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;
> > + }
>
> i think this is ok.
>
> > + int ret;
> > +
> > + /* 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");
>
> how about "no memory for device state"
>
Ok.
> > + 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)
> > + goto error_free;
>
> do all return paths of diolan_init() print error?
>
No. I'll add a message.
> > +
> > + /* 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;
> > +}
> > +
>
Thanks a lot for the review!
Guenter
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