[v8,1/4] mfd: add support for Diolan DLN-2 devices
diff mbox

Message ID 1413384491-23703-2-git-send-email-octavian.purdila@intel.com
State Not Applicable
Headers show

Commit Message

Octavian Purdila Oct. 15, 2014, 2:48 p.m. UTC
This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
Master Adapter DLN-2. Details about the device can be found here:

https://www.diolan.com/i2c/i2c_interface.html.

Information about the USB protocol can be found in the Programmer's
Reference Manual [1], see section 1.7.

Because the hardware has a single transmit endpoint and a single
receive endpoint the communication between the various DLN2 drivers
and the hardware will be muxed/demuxed by this driver.

Each DLN2 module will be identified by the handle field within the DLN2
message header. If a DLN2 module issues multiple commands in parallel
they will be identified by the echo counter field in the message header.

The DLN2 modules can use the dln2_transfer() function to issue a
command and wait for its response. They can also register a callback
that is going to be called when a specific event id is generated by
the device (e.g. GPIO interrupts). The device uses handle 0 for
sending events.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/mfd/Kconfig      |  11 +
 drivers/mfd/Makefile     |   1 +
 drivers/mfd/dln2.c       | 756 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/dln2.h |  69 +++++
 4 files changed, 837 insertions(+)
 create mode 100644 drivers/mfd/dln2.c
 create mode 100644 include/linux/mfd/dln2.h

Comments

Johan Hovold Oct. 23, 2014, 3:16 p.m. UTC | #1
On Wed, Oct 15, 2014 at 05:48:08PM +0300, Octavian Purdila wrote:

Here's some late feedback due to travels. You managed to get two updates
in there so commenting on the diff from v6.

> +struct dln2_event_cb_entry {
> +	struct list_head list;
> +	u16 id;
> +	struct platform_device *pdev;
> +	dln2_event_cb_t callback;
> +};
> +
> +int dln2_register_event_cb(struct platform_device *pdev, u16 id,
> +			   dln2_event_cb_t rx_cb)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_event_cb_entry *i, *new_cb;

Can you use a name which does not have the same suffix as the actual
callback function (i.e. "_cb"). Just call it "entry" or something.

> +	unsigned long flags;
> +	int ret = 0;
> +
> +	new_cb = kmalloc(sizeof(*new_cb), GFP_KERNEL);

Use kzalloc here.

> +	if (!new_cb)
> +		return -ENOMEM;
> +
> +	new_cb->id = id;
> +	new_cb->callback = rx_cb;
> +	new_cb->pdev = pdev;
> +
> +	spin_lock_irqsave(&dln2->event_cb_lock, flags);
> +
> +	list_for_each_entry(i, &dln2->event_cb_list, list) {
> +		if (i->id == id) {
> +			ret = -EBUSY;
> +			break;
> +		}
> +	}
> +
> +	if (!ret)
> +		list_add_rcu(&new_cb->list, &dln2->event_cb_list);
> +
> +	spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
> +
> +	if (ret)
> +		kfree(new_cb);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(dln2_register_event_cb);
> +
> +void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_event_cb_entry *i;
> +	unsigned long flags;
> +	bool found = false;
> +
> +	spin_lock_irqsave(&dln2->event_cb_lock, flags);
> +
> +	list_for_each_entry(i, &dln2->event_cb_list, list) {
> +		if (i->id == id) {
> +			list_del_rcu(&i->list);
> +			found = true;
> +			break;
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
> +
> +	if (found) {
> +		synchronize_rcu();
> +		kfree(i);
> +	}
> +}
> +EXPORT_SYMBOL(dln2_unregister_event_cb);
> +

Please add a comment describing the return value (i.e. when the urb had
been saved and shouldn't be resubmitted).

Also could rename this helper so it doesn't appear to be a variant of
dln2_transfer (e.g. something with "complete" in the name).

> +static bool dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
> +			     u16 handle, u16 rx_slot)
> +{
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +	struct dln2_rx_context *rxc;
> +	bool ret = false;
> +
> +	rxc = &rxs->slots[rx_slot];
> +
> +	/*
> +	 * No need to disable interrupts as this lock is not taken in
> +	 * interrupt context elsewhere in this driver and this
> +	 * function (or its callers) are not exported to other
> +	 * modules.

Why do you break comment lines already at 70 chars?

> +	 */
> +	spin_lock(&rxs->lock);
> +	if (rxc->in_use && !rxc->urb) {
> +		rxc->urb = urb;
> +		complete(&rxc->done);
> +		ret = true;
> +	}
> +	spin_unlock(&rxs->lock);
> +
> +	return ret;
> +}
> +
> +static void dln2_run_event_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
> +				     void *data, int len)
> +{
> +	struct dln2_event_cb_entry *i;
> +
> +	rcu_read_lock();
> +
> +	list_for_each_entry_rcu(i, &dln2->event_cb_list, list)
> +		if (i->id == id)
> +			i->callback(i->pdev, echo, data, len);
> +
> +	rcu_read_unlock();
> +}
> +
> +static void dln2_rx(struct urb *urb)
> +{
> +	struct dln2_dev *dln2 = urb->context;
> +	struct dln2_header *hdr = urb->transfer_buffer;
> +	struct device *dev = &dln2->interface->dev;
> +	u16 id, echo, handle, size;
> +	u8 *data;
> +	int len;
> +	int err;
> +
> +	switch (urb->status) {
> +	case 0:
> +		/* success */
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +	case -EPIPE:
> +		/* this urb is terminated, clean up */
> +		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
> +		return;
> +	default:
> +		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
> +		goto out;
> +	}
> +
> +	if (urb->actual_length < sizeof(struct dln2_header)) {
> +		dev_err(dev, "short response: %d\n", urb->actual_length);
> +		goto out;
> +	}
> +
> +	handle = le16_to_cpu(hdr->handle);
> +	id = le16_to_cpu(hdr->id);
> +	echo = le16_to_cpu(hdr->echo);
> +	size = le16_to_cpu(hdr->size);
> +
> +	if (size != urb->actual_length) {
> +		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
> +			handle, id, echo, size, urb->actual_length);
> +		goto out;
> +	}
> +
> +	if (handle >= DLN2_HANDLES) {
> +		dev_warn(dev, "RX: invalid handle %d\n", handle);
> +		goto out;
> +	}
> +
> +	data = urb->transfer_buffer + sizeof(struct dln2_header);
> +	len = urb->actual_length - sizeof(struct dln2_header);
> +
> +	if (handle == DLN2_HANDLE_EVENT) {
> +		dln2_run_event_callbacks(dln2, id, echo, data, len);
> +	} else {
> +		/* URB will be re-submitted in free_rx_slot */

Refer to _dln2_transfer (the only place where free_rx_slot is used) as
well.

> +		if (dln2_rx_transfer(dln2, urb, handle, echo))
> +			return;
> +		dev_warn(dev, "bad/late response %d/%d\n", handle, echo);

Move this message back to the helper.

> +	}
> +
> +out:
> +	err = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (err < 0)
> +		dev_err(dev, "failed to resubmit RX URB: %d\n", err);
> +}
> +

[...]

> +static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
> +			      struct usb_host_interface *hostif)
> +{
> +	int i;
> +	const int rx_max_size = DLN2_RX_BUF_SIZE;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		int ret;
> +		struct device *dev = &dln2->interface->dev;

Move these out of the loop.

> +
> +		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
> +		if (!dln2->rx_buf[i])
> +			return -ENOMEM;
> +
> +		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
> +		if (!dln2->rx_urb[i])
> +			return -ENOMEM;
> +
> +		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
> +				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
> +				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
> +
> +		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to submit RX URB: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct dln2_platform_data dln2_pdata_gpio = {
> +	.handle = DLN2_HANDLE_GPIO,
> +};
> +
> +/* Only one I2C port seems to be supported on current hardware */
> +static struct dln2_platform_data dln2_pdata_i2c = {
> +	.handle = DLN2_HANDLE_I2C,
> +	.port = 0,
> +};
> +
> +static const struct mfd_cell dln2_devs[] = {
> +	{
> +		.name = "dln2-gpio",
> +		.platform_data = &dln2_pdata_gpio,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +	{
> +		.name = "dln2-i2c",
> +		.platform_data = &dln2_pdata_i2c,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +};
> +
> +static void dln2_disconnect(struct usb_interface *interface)
> +{
> +	struct dln2_dev *dln2 = usb_get_intfdata(interface);
> +	int i, j;
> +
> +	/* don't allow starting new transfers */
> +	spin_lock(&dln2->disconnect_lock);
> +	dln2->disconnect = true;
> +	spin_unlock(&dln2->disconnect_lock);
> +
> +	/* cancel in progress transfers */
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&rxs->lock, flags);
> +
> +		/* cancel all response waiters */
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
> +			struct dln2_rx_context *rxc = &rxs->slots[j];
> +
> +			if (rxc->in_use)
> +				complete(&rxc->done);
> +		}
> +
> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +	}
> +
> +	/* wait for transfers to end */
> +	wait_event(dln2->disconnect_wq, !dln2->active_transfers);
> +
> +	mfd_remove_devices(&interface->dev);
> +
> +	dln2_free(dln2);
> +}
> +
> +static int dln2_probe(struct usb_interface *interface,
> +		      const struct usb_device_id *usb_id)
> +{
> +	struct usb_host_interface *hostif = interface->cur_altsetting;
> +	struct device *dev = &interface->dev;
> +	struct dln2_dev *dln2;
> +	int ret;
> +	int i, j;
> +
> +	if (hostif->desc.bInterfaceNumber != 0 ||
> +	    hostif->desc.bNumEndpoints < 2)
> +		return -ENODEV;
> +
> +	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
> +	if (!dln2)
> +		return -ENOMEM;
> +
> +	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
> +	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
> +	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> +	dln2->interface = interface;
> +	usb_set_intfdata(interface, dln2);
> +	init_waitqueue_head(&dln2->disconnect_wq);
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
> +		spin_lock_init(&dln2->mod_rx_slots[i].lock);
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
> +			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
> +	}
> +
> +	spin_lock_init(&dln2->event_cb_lock);
> +	spin_lock_init(&dln2->disconnect_lock);
> +	INIT_LIST_HEAD(&dln2->event_cb_list);
> +
> +	ret = dln2_setup_rx_urbs(dln2, hostif);
> +	if (ret)
> +		goto out_cleanup;
> +
> +	ret = dln2_hw_init(dln2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to initialize hardware\n");
> +		goto out_cleanup;
> +	}
> +
> +	ret = mfd_add_hotplug_devices(dev, dln2_devs, ARRAY_SIZE(dln2_devs));

So this now depends on 15bb4d6e8534 ("mfd: core: Add helper function to
register hotplug devices") in the MFD tree.

Please mention what tree the patch is against in your cover letter (I
noticed you had rebased when it no longer applied to 3.17).

You should drop the gpiolib patch now that v3.18-rc1 is out as well.

> +	if (ret != 0) {
> +		dev_err(dev, "failed to add mfd devices to core\n");
> +		goto out_cleanup;
> +	}
> +
> +	return 0;
> +
> +out_cleanup:
> +	dln2_free(dln2);
> +
> +	return ret;
> +}
> +
> +static const struct usb_device_id dln2_table[] = {
> +	{ USB_DEVICE(0xa257, 0x2013) },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(usb, dln2_table);
> +
> +static struct usb_driver dln2_driver = {
> +	.name = "dln2",
> +	.probe = dln2_probe,
> +	.disconnect = dln2_disconnect,
> +	.id_table = dln2_table,
> +};
> +
> +module_usb_driver(dln2_driver);
> +
> +MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
> +MODULE_DESCRIPTION("Core driver for the Diolan DLN2 interface adapter");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
> new file mode 100644
> index 0000000..57ddc58
> --- /dev/null
> +++ b/include/linux/mfd/dln2.h
> @@ -0,0 +1,69 @@
> +#ifndef __LINUX_USB_DLN2_H
> +#define __LINUX_USB_DLN2_H
> +
> +#define DLN2_CMD(cmd, id)		((cmd) | ((id) << 8))
> +
> +struct dln2_platform_data {
> +	u16 handle;		/* sub-driver handle (internally used only) */
> +	u8 port;		/* I2C/SPI port */
> +};
> +
> +/**
> + * dln2_event_cb_t - event callback function signature
> + *
> + * @pdev - the sub-device that registered this callback
> + * @echo - the echo header field received in the message
> + * @data - the data payload
> + * @len  - the data payload length
> + *
> + * The callback function is called in interrupt context and the data
> + * payload is only valid during the call. If the user needs later
> + * access of the data, it must copy it.
> + */
> +
> +typedef void (*dln2_event_cb_t)(struct platform_device *pdev, u16 echo,
> +				const void *data, int len);
> +
> +/**
> + * dl2n_register_event_cb - register a callback function for an event
> + *
> + * @pdev - the sub-device that registers the callback
> + * @event - the event for which to register a callback
> + * @event_cb - the callback function
> + *
> + * @return 0 in case of success, negative value in case of error
> + */
> +int dln2_register_event_cb(struct platform_device *pdev, u16 event,
> +			   dln2_event_cb_t event_cb);
> +
> +/**
> + * dln2_unregister_event_cb - unregister the callback function for an event
> + *
> + * @pdev - the sub-device that registered the callback
> + * @event - the event for which to register a callback
> + */
> +void dln2_unregister_event_cb(struct platform_device *pdev, u16 event);
> +
> +/**
> + * dln2_transfer - issue a DLN2 command and wait for a response and
> + * the associated data
> + *
> + * @pdev - the sub-device which is issuing this transfer
> + * @cmd - the command to be sent to the device
> + * @obuf - the buffer to be sent to the device; it can be NULL if the
> + *	user doesn't need to transmit data with this command
> + * @obuf_len - the size of the buffer to be sent to the device
> + * @ibuf - any data associated with the response will be copied here;
> + *	it can be NULL if the user doesn't need the response data
> + * @ibuf_len - must be initialized to the input buffer size; it will
> + *	be modified to indicate the actual data transfered;
> + * @result - pointer to store the result code received from hardware;
> + *	it can be NULL if the user doesn't need the result code
> + *
> + * @return 0 for success, negative value for errors
> + */
> +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> +		  const void *obuf, unsigned obuf_len,
> +		  void *ibuf, unsigned *ibuf_len, u16 *result);

Why add yet another parameter for the result and then never even use it?
Please remove it. You can add a new function for it (and a wrapper)
later if it's ever needed.

You should also consider adding a convenience function for when you
don't care about any returned data (e.g. dln2_transfer_tx) so you don't
have to pass all those NULLs (most calls currently have three NULL
params).

> +
> +#endif

Johan
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Octavian Purdila Oct. 27, 2014, 1:21 p.m. UTC | #2
On Thu, Oct 23, 2014 at 6:16 PM, Johan Hovold <johan@kernel.org> wrote:
>
> On Wed, Oct 15, 2014 at 05:48:08PM +0300, Octavian Purdila wrote:
>
> Here's some late feedback due to travels. You managed to get two updates
> in there so commenting on the diff from v6.
>

Thanks for the review :)

> > +struct dln2_event_cb_entry {
> > +     struct list_head list;
> > +     u16 id;
> > +     struct platform_device *pdev;
> > +     dln2_event_cb_t callback;
> > +};
> > +
> > +int dln2_register_event_cb(struct platform_device *pdev, u16 id,
> > +                        dln2_event_cb_t rx_cb)
> > +{
> > +     struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> > +     struct dln2_event_cb_entry *i, *new_cb;
>
> Can you use a name which does not have the same suffix as the actual
> callback function (i.e. "_cb"). Just call it "entry" or something.
>

OK.

> > +     unsigned long flags;
> > +     int ret = 0;
> > +
> > +     new_cb = kmalloc(sizeof(*new_cb), GFP_KERNEL);
>
> Use kzalloc here.

Why kzalloc? All of the fields are initialized below.

>
> > +     if (!new_cb)
> > +             return -ENOMEM;
> > +
> > +     new_cb->id = id;
> > +     new_cb->callback = rx_cb;
> > +     new_cb->pdev = pdev;
> > +
> > +     spin_lock_irqsave(&dln2->event_cb_lock, flags);
> > +
> > +     list_for_each_entry(i, &dln2->event_cb_list, list) {
> > +             if (i->id == id) {
> > +                     ret = -EBUSY;
> > +                     break;
> > +             }
> > +     }
> > +
> > +     if (!ret)
> > +             list_add_rcu(&new_cb->list, &dln2->event_cb_list);
> > +
> > +     spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
> > +
> > +     if (ret)
> > +             kfree(new_cb);
> > +
> > +     return ret;
> > +}
> > +EXPORT_SYMBOL(dln2_register_event_cb);
> > +
> > +void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
> > +{
> > +     struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> > +     struct dln2_event_cb_entry *i;
> > +     unsigned long flags;
> > +     bool found = false;
> > +
> > +     spin_lock_irqsave(&dln2->event_cb_lock, flags);
> > +
> > +     list_for_each_entry(i, &dln2->event_cb_list, list) {
> > +             if (i->id == id) {
> > +                     list_del_rcu(&i->list);
> > +                     found = true;
> > +                     break;
> > +             }
> > +     }
> > +
> > +     spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
> > +
> > +     if (found) {
> > +             synchronize_rcu();
> > +             kfree(i);
> > +     }
> > +}
> > +EXPORT_SYMBOL(dln2_unregister_event_cb);
> > +
>
> Please add a comment describing the return value (i.e. when the urb had
> been saved and shouldn't be resubmitted).
>
> Also could rename this helper so it doesn't appear to be a variant of
> dln2_transfer (e.g. something with "complete" in the name).
>

Ok, I will use dln2_transfer_complete.

> > +static bool dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
> > +                          u16 handle, u16 rx_slot)
> > +{
> > +     struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> > +     struct dln2_rx_context *rxc;
> > +     bool ret = false;
> > +
> > +     rxc = &rxs->slots[rx_slot];
> > +
> > +     /*
> > +      * No need to disable interrupts as this lock is not taken in
> > +      * interrupt context elsewhere in this driver and this
> > +      * function (or its callers) are not exported to other
> > +      * modules.
>
> Why do you break comment lines already at 70 chars?
>

Oops, relic in my .emacs, will fix all comments in v9.

> > +      */
> > +     spin_lock(&rxs->lock);
> > +     if (rxc->in_use && !rxc->urb) {
> > +             rxc->urb = urb;
> > +             complete(&rxc->done);
> > +             ret = true;
> > +     }
> > +     spin_unlock(&rxs->lock);
> > +
> > +     return ret;
> > +}
> > +
> > +static void dln2_run_event_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
> > +                                  void *data, int len)
> > +{
> > +     struct dln2_event_cb_entry *i;
> > +
> > +     rcu_read_lock();
> > +
> > +     list_for_each_entry_rcu(i, &dln2->event_cb_list, list)
> > +             if (i->id == id)
> > +                     i->callback(i->pdev, echo, data, len);
> > +
> > +     rcu_read_unlock();
> > +}
> > +
> > +static void dln2_rx(struct urb *urb)
> > +{
> > +     struct dln2_dev *dln2 = urb->context;
> > +     struct dln2_header *hdr = urb->transfer_buffer;
> > +     struct device *dev = &dln2->interface->dev;
> > +     u16 id, echo, handle, size;
> > +     u8 *data;
> > +     int len;
> > +     int err;
> > +
> > +     switch (urb->status) {
> > +     case 0:
> > +             /* success */
> > +             break;
> > +     case -ECONNRESET:
> > +     case -ENOENT:
> > +     case -ESHUTDOWN:
> > +     case -EPIPE:
> > +             /* this urb is terminated, clean up */
> > +             dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
> > +             return;
> > +     default:
> > +             dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
> > +             goto out;
> > +     }
> > +
> > +     if (urb->actual_length < sizeof(struct dln2_header)) {
> > +             dev_err(dev, "short response: %d\n", urb->actual_length);
> > +             goto out;
> > +     }
> > +
> > +     handle = le16_to_cpu(hdr->handle);
> > +     id = le16_to_cpu(hdr->id);
> > +     echo = le16_to_cpu(hdr->echo);
> > +     size = le16_to_cpu(hdr->size);
> > +
> > +     if (size != urb->actual_length) {
> > +             dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
> > +                     handle, id, echo, size, urb->actual_length);
> > +             goto out;
> > +     }
> > +
> > +     if (handle >= DLN2_HANDLES) {
> > +             dev_warn(dev, "RX: invalid handle %d\n", handle);
> > +             goto out;
> > +     }
> > +
> > +     data = urb->transfer_buffer + sizeof(struct dln2_header);
> > +     len = urb->actual_length - sizeof(struct dln2_header);
> > +
> > +     if (handle == DLN2_HANDLE_EVENT) {
> > +             dln2_run_event_callbacks(dln2, id, echo, data, len);
> > +     } else {
> > +             /* URB will be re-submitted in free_rx_slot */
>
> Refer to _dln2_transfer (the only place where free_rx_slot is used) as
> well.
>

OK.

> > +             if (dln2_rx_transfer(dln2, urb, handle, echo))
> > +                     return;
> > +             dev_warn(dev, "bad/late response %d/%d\n", handle, echo);
>
> Move this message back to the helper.
>

OK.

> > +     }
> > +
> > +out:
> > +     err = usb_submit_urb(urb, GFP_ATOMIC);
> > +     if (err < 0)
> > +             dev_err(dev, "failed to resubmit RX URB: %d\n", err);
> > +}
> > +
>
> [...]
>
> > +static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
> > +                           struct usb_host_interface *hostif)
> > +{
> > +     int i;
> > +     const int rx_max_size = DLN2_RX_BUF_SIZE;
> > +
> > +     for (i = 0; i < DLN2_MAX_URBS; i++) {
> > +             int ret;
> > +             struct device *dev = &dln2->interface->dev;
>
> Move these out of the loop.
>
> > +
> > +             dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
> > +             if (!dln2->rx_buf[i])
> > +                     return -ENOMEM;
> > +
> > +             dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
> > +             if (!dln2->rx_urb[i])
> > +                     return -ENOMEM;
> > +
> > +             usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
> > +                               usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
> > +                               dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
> > +
> > +             ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
> > +             if (ret < 0) {
> > +                     dev_err(dev, "failed to submit RX URB: %d\n", ret);
> > +                     return ret;
> > +             }
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static struct dln2_platform_data dln2_pdata_gpio = {
> > +     .handle = DLN2_HANDLE_GPIO,
> > +};
> > +
> > +/* Only one I2C port seems to be supported on current hardware */
> > +static struct dln2_platform_data dln2_pdata_i2c = {
> > +     .handle = DLN2_HANDLE_I2C,
> > +     .port = 0,
> > +};
> > +
> > +static const struct mfd_cell dln2_devs[] = {
> > +     {
> > +             .name = "dln2-gpio",
> > +             .platform_data = &dln2_pdata_gpio,
> > +             .pdata_size = sizeof(struct dln2_platform_data),
> > +     },
> > +     {
> > +             .name = "dln2-i2c",
> > +             .platform_data = &dln2_pdata_i2c,
> > +             .pdata_size = sizeof(struct dln2_platform_data),
> > +     },
> > +};
> > +
> > +static void dln2_disconnect(struct usb_interface *interface)
> > +{
> > +     struct dln2_dev *dln2 = usb_get_intfdata(interface);
> > +     int i, j;
> > +
> > +     /* don't allow starting new transfers */
> > +     spin_lock(&dln2->disconnect_lock);
> > +     dln2->disconnect = true;
> > +     spin_unlock(&dln2->disconnect_lock);
> > +
> > +     /* cancel in progress transfers */
> > +     for (i = 0; i < DLN2_HANDLES; i++) {
> > +             struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
> > +             unsigned long flags;
> > +
> > +             spin_lock_irqsave(&rxs->lock, flags);
> > +
> > +             /* cancel all response waiters */
> > +             for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
> > +                     struct dln2_rx_context *rxc = &rxs->slots[j];
> > +
> > +                     if (rxc->in_use)
> > +                             complete(&rxc->done);
> > +             }
> > +
> > +             spin_unlock_irqrestore(&rxs->lock, flags);
> > +     }
> > +
> > +     /* wait for transfers to end */
> > +     wait_event(dln2->disconnect_wq, !dln2->active_transfers);
> > +
> > +     mfd_remove_devices(&interface->dev);
> > +
> > +     dln2_free(dln2);
> > +}
> > +
> > +static int dln2_probe(struct usb_interface *interface,
> > +                   const struct usb_device_id *usb_id)
> > +{
> > +     struct usb_host_interface *hostif = interface->cur_altsetting;
> > +     struct device *dev = &interface->dev;
> > +     struct dln2_dev *dln2;
> > +     int ret;
> > +     int i, j;
> > +
> > +     if (hostif->desc.bInterfaceNumber != 0 ||
> > +         hostif->desc.bNumEndpoints < 2)
> > +             return -ENODEV;
> > +
> > +     dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
> > +     if (!dln2)
> > +             return -ENOMEM;
> > +
> > +     dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
> > +     dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
> > +     dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> > +     dln2->interface = interface;
> > +     usb_set_intfdata(interface, dln2);
> > +     init_waitqueue_head(&dln2->disconnect_wq);
> > +
> > +     for (i = 0; i < DLN2_HANDLES; i++) {
> > +             init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
> > +             spin_lock_init(&dln2->mod_rx_slots[i].lock);
> > +             for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
> > +                     init_completion(&dln2->mod_rx_slots[i].slots[j].done);
> > +     }
> > +
> > +     spin_lock_init(&dln2->event_cb_lock);
> > +     spin_lock_init(&dln2->disconnect_lock);
> > +     INIT_LIST_HEAD(&dln2->event_cb_list);
> > +
> > +     ret = dln2_setup_rx_urbs(dln2, hostif);
> > +     if (ret)
> > +             goto out_cleanup;
> > +
> > +     ret = dln2_hw_init(dln2);
> > +     if (ret < 0) {
> > +             dev_err(dev, "failed to initialize hardware\n");
> > +             goto out_cleanup;
> > +     }
> > +
> > +     ret = mfd_add_hotplug_devices(dev, dln2_devs, ARRAY_SIZE(dln2_devs));
>
> So this now depends on 15bb4d6e8534 ("mfd: core: Add helper function to
> register hotplug devices") in the MFD tree.
>
> Please mention what tree the patch is against in your cover letter (I
> noticed you had rebased when it no longer applied to 3.17).
>
> You should drop the gpiolib patch now that v3.18-rc1 is out as well.

This series is based against the Lee's for-mfd-next-v3.19 tree that
does not yet contain the gpiolib patch.

>
> > +     if (ret != 0) {
> > +             dev_err(dev, "failed to add mfd devices to core\n");
> > +             goto out_cleanup;
> > +     }
> > +
> > +     return 0;
> > +
> > +out_cleanup:
> > +     dln2_free(dln2);
> > +
> > +     return ret;
> > +}
> > +
> > +static const struct usb_device_id dln2_table[] = {
> > +     { USB_DEVICE(0xa257, 0x2013) },
> > +     { }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(usb, dln2_table);
> > +
> > +static struct usb_driver dln2_driver = {
> > +     .name = "dln2",
> > +     .probe = dln2_probe,
> > +     .disconnect = dln2_disconnect,
> > +     .id_table = dln2_table,
> > +};
> > +
> > +module_usb_driver(dln2_driver);
> > +
> > +MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
> > +MODULE_DESCRIPTION("Core driver for the Diolan DLN2 interface adapter");
> > +MODULE_LICENSE("GPL v2");
> > diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
> > new file mode 100644
> > index 0000000..57ddc58
> > --- /dev/null
> > +++ b/include/linux/mfd/dln2.h
> > @@ -0,0 +1,69 @@
> > +#ifndef __LINUX_USB_DLN2_H
> > +#define __LINUX_USB_DLN2_H
> > +
> > +#define DLN2_CMD(cmd, id)            ((cmd) | ((id) << 8))
> > +
> > +struct dln2_platform_data {
> > +     u16 handle;             /* sub-driver handle (internally used only) */
> > +     u8 port;                /* I2C/SPI port */
> > +};
> > +
> > +/**
> > + * dln2_event_cb_t - event callback function signature
> > + *
> > + * @pdev - the sub-device that registered this callback
> > + * @echo - the echo header field received in the message
> > + * @data - the data payload
> > + * @len  - the data payload length
> > + *
> > + * The callback function is called in interrupt context and the data
> > + * payload is only valid during the call. If the user needs later
> > + * access of the data, it must copy it.
> > + */
> > +
> > +typedef void (*dln2_event_cb_t)(struct platform_device *pdev, u16 echo,
> > +                             const void *data, int len);
> > +
> > +/**
> > + * dl2n_register_event_cb - register a callback function for an event
> > + *
> > + * @pdev - the sub-device that registers the callback
> > + * @event - the event for which to register a callback
> > + * @event_cb - the callback function
> > + *
> > + * @return 0 in case of success, negative value in case of error
> > + */
> > +int dln2_register_event_cb(struct platform_device *pdev, u16 event,
> > +                        dln2_event_cb_t event_cb);
> > +
> > +/**
> > + * dln2_unregister_event_cb - unregister the callback function for an event
> > + *
> > + * @pdev - the sub-device that registered the callback
> > + * @event - the event for which to register a callback
> > + */
> > +void dln2_unregister_event_cb(struct platform_device *pdev, u16 event);
> > +
> > +/**
> > + * dln2_transfer - issue a DLN2 command and wait for a response and
> > + * the associated data
> > + *
> > + * @pdev - the sub-device which is issuing this transfer
> > + * @cmd - the command to be sent to the device
> > + * @obuf - the buffer to be sent to the device; it can be NULL if the
> > + *   user doesn't need to transmit data with this command
> > + * @obuf_len - the size of the buffer to be sent to the device
> > + * @ibuf - any data associated with the response will be copied here;
> > + *   it can be NULL if the user doesn't need the response data
> > + * @ibuf_len - must be initialized to the input buffer size; it will
> > + *   be modified to indicate the actual data transfered;
> > + * @result - pointer to store the result code received from hardware;
> > + *   it can be NULL if the user doesn't need the result code
> > + *
> > + * @return 0 for success, negative value for errors
> > + */
> > +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> > +               const void *obuf, unsigned obuf_len,
> > +               void *ibuf, unsigned *ibuf_len, u16 *result);
>
> Why add yet another parameter for the result and then never even use it?
> Please remove it. You can add a new function for it (and a wrapper)
> later if it's ever needed.
>

It is needed for setting the frequency, but you are right I should add
it with that patch set.

> You should also consider adding a convenience function for when you
> don't care about any returned data (e.g. dln2_transfer_tx) so you don't
> have to pass all those NULLs (most calls currently have three NULL
> params).
>

OK, will do it in v9.
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Johan Hovold Oct. 27, 2014, 2:36 p.m. UTC | #3
On Mon, Oct 27, 2014 at 03:21:10PM +0200, Octavian Purdila wrote:
> On Thu, Oct 23, 2014 at 6:16 PM, Johan Hovold <johan@kernel.org> wrote:
> > On Wed, Oct 15, 2014 at 05:48:08PM +0300, Octavian Purdila wrote:

> > > +struct dln2_event_cb_entry {
> > > +     struct list_head list;
> > > +     u16 id;
> > > +     struct platform_device *pdev;
> > > +     dln2_event_cb_t callback;
> > > +};
> > > +
> > > +int dln2_register_event_cb(struct platform_device *pdev, u16 id,
> > > +                        dln2_event_cb_t rx_cb)
> > > +{
> > > +     struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> > > +     struct dln2_event_cb_entry *i, *new_cb;
> >
> > Can you use a name which does not have the same suffix as the actual
> > callback function (i.e. "_cb"). Just call it "entry" or something.
> >
> 
> OK.
> 
> > > +     unsigned long flags;
> > > +     int ret = 0;
> > > +
> > > +     new_cb = kmalloc(sizeof(*new_cb), GFP_KERNEL);
> >
> > Use kzalloc here.
> 
> Why kzalloc? All of the fields are initialized below.

It's good practise to clear any data structure at allocation. The cost
is negligible.
 
> > > +     if (!new_cb)
> > > +             return -ENOMEM;
> > > +
> > > +     new_cb->id = id;
> > > +     new_cb->callback = rx_cb;
> > > +     new_cb->pdev = pdev;
> > > +
> > > +     spin_lock_irqsave(&dln2->event_cb_lock, flags);
> > > +
> > > +     list_for_each_entry(i, &dln2->event_cb_list, list) {
> > > +             if (i->id == id) {
> > > +                     ret = -EBUSY;
> > > +                     break;
> > > +             }
> > > +     }
> > > +
> > > +     if (!ret)
> > > +             list_add_rcu(&new_cb->list, &dln2->event_cb_list);
> > > +
> > > +     spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
> > > +
> > > +     if (ret)
> > > +             kfree(new_cb);
> > > +
> > > +     return ret;
> > > +}
> > > +EXPORT_SYMBOL(dln2_register_event_cb);

> > > +     ret = mfd_add_hotplug_devices(dev, dln2_devs, ARRAY_SIZE(dln2_devs));
> >
> > So this now depends on 15bb4d6e8534 ("mfd: core: Add helper function to
> > register hotplug devices") in the MFD tree.
> >
> > Please mention what tree the patch is against in your cover letter (I
> > noticed you had rebased when it no longer applied to 3.17).
> >
> > You should drop the gpiolib patch now that v3.18-rc1 is out as well.
> 
> This series is based against the Lee's for-mfd-next-v3.19 tree that
> does not yet contain the gpiolib patch.

Ok, but make sure to include that information in the cover letter.

Johan
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Patch
diff mbox

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index c9200d3..4538815a 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -189,6 +189,17 @@  config MFD_DA9063
 	  Additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_DLN2
+	tristate "Diolan DLN2 support"
+	select MFD_CORE
+	depends on USB
+	help
+
+	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter
+	  DLN-2. Additional drivers such as I2C_DLN2, GPIO_DLN2,
+	  etc. must be enabled in order to use the functionality of
+	  the device.
+
 config MFD_MC13XXX
 	tristate
 	depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 61f8dbf..2cd7e74 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -175,6 +175,7 @@  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
 obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
 obj-$(CONFIG_MFD_MENF21BMC)	+= menf21bmc.o
 obj-$(CONFIG_MFD_HI6421_PMIC)	+= hi6421-pmic-core.o
+obj-$(CONFIG_MFD_DLN2)		+= dln2.o
 
 intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
 obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
new file mode 100644
index 0000000..124b262
--- /dev/null
+++ b/drivers/mfd/dln2.c
@@ -0,0 +1,756 @@ 
+/*
+ * Driver for the Diolan DLN-2 USB adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Derived from:
+ *  i2c-diolan-u2c.c
+ *  Copyright (c) 2010-2011 Ericsson AB
+ *
+ * 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/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/dln2.h>
+#include <linux/rculist.h>
+
+struct dln2_header {
+	__le16 size;
+	__le16 id;
+	__le16 echo;
+	__le16 handle;
+} __packed;
+
+struct dln2_response {
+	struct dln2_header hdr;
+	__le16 result;
+} __packed;
+
+#define DLN2_GENERIC_MODULE_ID		0x00
+#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
+#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
+#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
+
+#define DLN2_HW_ID			0x200
+#define DLN2_USB_TIMEOUT		200	/* in ms */
+#define DLN2_MAX_RX_SLOTS		16
+#define DLN2_MAX_URBS			16
+#define DLN2_RX_BUF_SIZE		512
+
+enum dln2_handle {
+	DLN2_HANDLE_EVENT = 0,		/* don't change, hardware defined */
+	DLN2_HANDLE_CTRL,
+	DLN2_HANDLE_GPIO,
+	DLN2_HANDLE_I2C,
+	DLN2_HANDLES
+};
+
+/*
+ * Receive context used between the receive demultiplexer and the
+ * transfer routine. While sending a request the transfer routine
+ * will look for a free receive context and use it to wait for a
+ * response and to receive the URB and thus the response data.
+ */
+struct dln2_rx_context {
+	/* completion used to wait for a response */
+	struct completion done;
+
+	/* if non-NULL the URB contains the response */
+	struct urb *urb;
+
+	/* if true then this context is used to wait for a response */
+	bool in_use;
+};
+
+/*
+ * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
+ * use the handle header field to identify the module in
+ * dln2_dev.mod_rx_slots and then the echo header field to index the
+ * slots field and find the receive context for a particular request.
+ */
+struct dln2_mod_rx_slots {
+	/* RX slots bitmap */
+	DECLARE_BITMAP(bmap, DLN2_MAX_RX_SLOTS);
+
+	/* used to wait for a free RX slot */
+	wait_queue_head_t wq;
+
+	/* used to wait for an RX operation to complete */
+	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
+
+	/* avoid races between alloc/free_rx_slot and dln2_rx_transfer */
+	spinlock_t lock;
+};
+
+struct dln2_dev {
+	struct usb_device *usb_dev;
+	struct usb_interface *interface;
+	u8 ep_in;
+	u8 ep_out;
+
+	struct urb *rx_urb[DLN2_MAX_URBS];
+	void *rx_buf[DLN2_MAX_URBS];
+
+	struct dln2_mod_rx_slots mod_rx_slots[DLN2_HANDLES];
+
+	struct list_head event_cb_list;
+	spinlock_t event_cb_lock;
+
+	bool disconnect;
+	int active_transfers;
+	wait_queue_head_t disconnect_wq;
+	spinlock_t disconnect_lock;
+};
+
+struct dln2_event_cb_entry {
+	struct list_head list;
+	u16 id;
+	struct platform_device *pdev;
+	dln2_event_cb_t callback;
+};
+
+int dln2_register_event_cb(struct platform_device *pdev, u16 id,
+			   dln2_event_cb_t rx_cb)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_event_cb_entry *i, *new_cb;
+	unsigned long flags;
+	int ret = 0;
+
+	new_cb = kmalloc(sizeof(*new_cb), GFP_KERNEL);
+	if (!new_cb)
+		return -ENOMEM;
+
+	new_cb->id = id;
+	new_cb->callback = rx_cb;
+	new_cb->pdev = pdev;
+
+	spin_lock_irqsave(&dln2->event_cb_lock, flags);
+
+	list_for_each_entry(i, &dln2->event_cb_list, list) {
+		if (i->id == id) {
+			ret = -EBUSY;
+			break;
+		}
+	}
+
+	if (!ret)
+		list_add_rcu(&new_cb->list, &dln2->event_cb_list);
+
+	spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
+
+	if (ret)
+		kfree(new_cb);
+
+	return ret;
+}
+EXPORT_SYMBOL(dln2_register_event_cb);
+
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_event_cb_entry *i;
+	unsigned long flags;
+	bool found = false;
+
+	spin_lock_irqsave(&dln2->event_cb_lock, flags);
+
+	list_for_each_entry(i, &dln2->event_cb_list, list) {
+		if (i->id == id) {
+			list_del_rcu(&i->list);
+			found = true;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
+
+	if (found) {
+		synchronize_rcu();
+		kfree(i);
+	}
+}
+EXPORT_SYMBOL(dln2_unregister_event_cb);
+
+static bool dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
+			     u16 handle, u16 rx_slot)
+{
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+	struct dln2_rx_context *rxc;
+	bool ret = false;
+
+	rxc = &rxs->slots[rx_slot];
+
+	/*
+	 * No need to disable interrupts as this lock is not taken in
+	 * interrupt context elsewhere in this driver and this
+	 * function (or its callers) are not exported to other
+	 * modules.
+	 */
+	spin_lock(&rxs->lock);
+	if (rxc->in_use && !rxc->urb) {
+		rxc->urb = urb;
+		complete(&rxc->done);
+		ret = true;
+	}
+	spin_unlock(&rxs->lock);
+
+	return ret;
+}
+
+static void dln2_run_event_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
+				     void *data, int len)
+{
+	struct dln2_event_cb_entry *i;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(i, &dln2->event_cb_list, list)
+		if (i->id == id)
+			i->callback(i->pdev, echo, data, len);
+
+	rcu_read_unlock();
+}
+
+static void dln2_rx(struct urb *urb)
+{
+	struct dln2_dev *dln2 = urb->context;
+	struct dln2_header *hdr = urb->transfer_buffer;
+	struct device *dev = &dln2->interface->dev;
+	u16 id, echo, handle, size;
+	u8 *data;
+	int len;
+	int err;
+
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+	case -EPIPE:
+		/* this urb is terminated, clean up */
+		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
+		return;
+	default:
+		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
+		goto out;
+	}
+
+	if (urb->actual_length < sizeof(struct dln2_header)) {
+		dev_err(dev, "short response: %d\n", urb->actual_length);
+		goto out;
+	}
+
+	handle = le16_to_cpu(hdr->handle);
+	id = le16_to_cpu(hdr->id);
+	echo = le16_to_cpu(hdr->echo);
+	size = le16_to_cpu(hdr->size);
+
+	if (size != urb->actual_length) {
+		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
+			handle, id, echo, size, urb->actual_length);
+		goto out;
+	}
+
+	if (handle >= DLN2_HANDLES) {
+		dev_warn(dev, "RX: invalid handle %d\n", handle);
+		goto out;
+	}
+
+	data = urb->transfer_buffer + sizeof(struct dln2_header);
+	len = urb->actual_length - sizeof(struct dln2_header);
+
+	if (handle == DLN2_HANDLE_EVENT) {
+		dln2_run_event_callbacks(dln2, id, echo, data, len);
+	} else {
+		/* URB will be re-submitted in free_rx_slot */
+		if (dln2_rx_transfer(dln2, urb, handle, echo))
+			return;
+		dev_warn(dev, "bad/late response %d/%d\n", handle, echo);
+	}
+
+out:
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err < 0)
+		dev_err(dev, "failed to resubmit RX URB: %d\n", err);
+}
+
+static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
+			   int *obuf_len, gfp_t gfp)
+{
+	int len;
+	void *buf;
+	struct dln2_header *hdr;
+
+	len = *obuf_len + sizeof(*hdr);
+	buf = kmalloc(len, gfp);
+	if (!buf)
+		return NULL;
+
+	hdr = (struct dln2_header *)buf;
+	hdr->id = cpu_to_le16(cmd);
+	hdr->size = cpu_to_le16(len);
+	hdr->echo = cpu_to_le16(echo);
+	hdr->handle = cpu_to_le16(handle);
+
+	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
+
+	*obuf_len = len;
+
+	return buf;
+}
+
+static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
+			  const void *obuf, int obuf_len)
+{
+	int ret = 0;
+	int len = obuf_len;
+	void *buf;
+	int actual;
+
+	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(dln2->usb_dev,
+			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
+			   buf, len, &actual, DLN2_USB_TIMEOUT);
+
+	kfree(buf);
+
+	return ret;
+}
+
+static bool find_free_slot(struct dln2_dev *dln2, u16 handle, int *slot)
+{
+	struct dln2_mod_rx_slots *rxs;
+	unsigned long flags;
+
+	if (dln2->disconnect) {
+		*slot = -ENODEV;
+		return true;
+	}
+
+	rxs = &dln2->mod_rx_slots[handle];
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	*slot = find_first_zero_bit(rxs->bmap, DLN2_MAX_RX_SLOTS);
+
+	if (*slot < DLN2_MAX_RX_SLOTS) {
+		struct dln2_rx_context *rxc = &rxs->slots[*slot];
+
+		set_bit(*slot, rxs->bmap);
+		rxc->in_use = true;
+	}
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	return *slot < DLN2_MAX_RX_SLOTS;
+}
+
+static int alloc_rx_slot(struct dln2_dev *dln2, u16 handle)
+{
+	int ret;
+	int slot;
+
+	/*
+	 * No need to timeout here, the wait is bounded by the timeout
+	 * in _dln2_transfer.
+	 */
+	ret = wait_event_interruptible(dln2->mod_rx_slots[handle].wq,
+				       find_free_slot(dln2, handle, &slot));
+	if (ret < 0)
+		return ret;
+
+	return slot;
+}
+
+static void free_rx_slot(struct dln2_dev *dln2, u16 handle, int slot)
+{
+	struct dln2_mod_rx_slots *rxs;
+	struct urb *urb = NULL;
+	unsigned long flags;
+	struct dln2_rx_context *rxc;
+
+	rxs = &dln2->mod_rx_slots[handle];
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	clear_bit(slot, rxs->bmap);
+
+	rxc = &rxs->slots[slot];
+	rxc->in_use = false;
+	urb = rxc->urb;
+	rxc->urb = NULL;
+	reinit_completion(&rxc->done);
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (urb) {
+		int err;
+		struct device *dev = &dln2->interface->dev;
+
+		err = usb_submit_urb(urb, GFP_KERNEL);
+		if (err < 0)
+			dev_err(dev, "failed to resubmit RX URB: %d\n", err);
+	}
+
+	wake_up_interruptible(&rxs->wq);
+}
+
+static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
+			  const void *obuf, unsigned obuf_len,
+			  void *ibuf, unsigned *ibuf_len, u16 *result)
+{
+	int ret = 0;
+	int rx_slot;
+	struct dln2_response *rsp;
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+
+	spin_lock(&dln2->disconnect_lock);
+	if (!dln2->disconnect)
+		dln2->active_transfers++;
+	else
+		ret = -ENODEV;
+	spin_unlock(&dln2->disconnect_lock);
+
+	if (ret)
+		return ret;
+
+	rx_slot = alloc_rx_slot(dln2, handle);
+	if (rx_slot < 0) {
+		ret = rx_slot;
+		goto out_decr;
+	}
+
+	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
+	if (ret < 0) {
+		dev_err(dev, "USB write failed: %d\n", ret);
+		goto out_free_rx_slot;
+	}
+
+	rxc = &rxs->slots[rx_slot];
+
+	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
+	if (ret <= 0) {
+		if (!ret)
+			ret = -ETIMEDOUT;
+		goto out_free_rx_slot;
+	}
+
+	if (dln2->disconnect) {
+		ret = -ENODEV;
+		goto out_free_rx_slot;
+	}
+
+	/* if we got here we know that the response header has been checked */
+	rsp = rxc->urb->transfer_buffer;
+
+	if (rsp->hdr.size < sizeof(*rsp)) {
+		ret = -EPROTO;
+		goto out_free_rx_slot;
+	}
+
+	if (result)
+		*result = le16_to_cpu(rsp->result);
+	if (le16_to_cpu(rsp->result) > 0x80) {
+		dev_dbg(dev, "%d received response with error %d\n",
+			handle, le16_to_cpu(rsp->result));
+		ret = -EREMOTEIO;
+		goto out_free_rx_slot;
+	}
+
+	if (!ibuf) {
+		ret = 0;
+		goto out_free_rx_slot;
+	}
+
+	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
+		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
+
+	memcpy(ibuf, rsp + 1, *ibuf_len);
+
+out_free_rx_slot:
+	free_rx_slot(dln2, handle, rx_slot);
+out_decr:
+	spin_lock(&dln2->disconnect_lock);
+	dln2->active_transfers--;
+	spin_unlock(&dln2->disconnect_lock);
+	if (dln2->disconnect)
+		wake_up(&dln2->disconnect_wq);
+
+	return ret;
+}
+
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len, u16 *result)
+{
+	struct dln2_platform_data *dln2_pdata;
+	struct dln2_dev *dln2;
+	u16 handle;
+
+	dln2 = dev_get_drvdata(pdev->dev.parent);
+	dln2_pdata = dev_get_platdata(&pdev->dev);
+	handle = dln2_pdata->handle;
+
+	return _dln2_transfer(dln2, handle, cmd, obuf, obuf_len, ibuf, ibuf_len,
+			      result);
+}
+EXPORT_SYMBOL(dln2_transfer);
+
+static int dln2_check_hw(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 hw_type;
+	int len = sizeof(hw_type);
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
+			     NULL, 0, &hw_type, &len, NULL);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(hw_type))
+		return -EREMOTEIO;
+
+	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
+		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported\n",
+			le32_to_cpu(hw_type));
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int dln2_print_serialno(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 serial_no;
+	int len = sizeof(serial_no);
+	struct device *dev = &dln2->interface->dev;
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
+			     &serial_no, &len, NULL);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(serial_no))
+		return -EREMOTEIO;
+
+	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
+
+	return 0;
+}
+
+static int dln2_hw_init(struct dln2_dev *dln2)
+{
+	int ret;
+
+	ret = dln2_check_hw(dln2);
+	if (ret < 0)
+		return ret;
+
+	return dln2_print_serialno(dln2);
+}
+
+static void dln2_free_rx_urbs(struct dln2_dev *dln2)
+{
+	int i;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		usb_kill_urb(dln2->rx_urb[i]);
+		usb_free_urb(dln2->rx_urb[i]);
+		kfree(dln2->rx_buf[i]);
+	}
+}
+
+static void dln2_free(struct dln2_dev *dln2)
+{
+	dln2_free_rx_urbs(dln2);
+	usb_put_dev(dln2->usb_dev);
+	kfree(dln2);
+}
+
+static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
+			      struct usb_host_interface *hostif)
+{
+	int i;
+	const int rx_max_size = DLN2_RX_BUF_SIZE;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		int ret;
+		struct device *dev = &dln2->interface->dev;
+
+		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
+		if (!dln2->rx_buf[i])
+			return -ENOMEM;
+
+		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!dln2->rx_urb[i])
+			return -ENOMEM;
+
+		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
+				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
+				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
+
+		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
+		if (ret < 0) {
+			dev_err(dev, "failed to submit RX URB: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static struct dln2_platform_data dln2_pdata_gpio = {
+	.handle = DLN2_HANDLE_GPIO,
+};
+
+/* Only one I2C port seems to be supported on current hardware */
+static struct dln2_platform_data dln2_pdata_i2c = {
+	.handle = DLN2_HANDLE_I2C,
+	.port = 0,
+};
+
+static const struct mfd_cell dln2_devs[] = {
+	{
+		.name = "dln2-gpio",
+		.platform_data = &dln2_pdata_gpio,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+	{
+		.name = "dln2-i2c",
+		.platform_data = &dln2_pdata_i2c,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+};
+
+static void dln2_disconnect(struct usb_interface *interface)
+{
+	struct dln2_dev *dln2 = usb_get_intfdata(interface);
+	int i, j;
+
+	/* don't allow starting new transfers */
+	spin_lock(&dln2->disconnect_lock);
+	dln2->disconnect = true;
+	spin_unlock(&dln2->disconnect_lock);
+
+	/* cancel in progress transfers */
+	for (i = 0; i < DLN2_HANDLES; i++) {
+		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
+		unsigned long flags;
+
+		spin_lock_irqsave(&rxs->lock, flags);
+
+		/* cancel all response waiters */
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
+			struct dln2_rx_context *rxc = &rxs->slots[j];
+
+			if (rxc->in_use)
+				complete(&rxc->done);
+		}
+
+		spin_unlock_irqrestore(&rxs->lock, flags);
+	}
+
+	/* wait for transfers to end */
+	wait_event(dln2->disconnect_wq, !dln2->active_transfers);
+
+	mfd_remove_devices(&interface->dev);
+
+	dln2_free(dln2);
+}
+
+static int dln2_probe(struct usb_interface *interface,
+		      const struct usb_device_id *usb_id)
+{
+	struct usb_host_interface *hostif = interface->cur_altsetting;
+	struct device *dev = &interface->dev;
+	struct dln2_dev *dln2;
+	int ret;
+	int i, j;
+
+	if (hostif->desc.bInterfaceNumber != 0 ||
+	    hostif->desc.bNumEndpoints < 2)
+		return -ENODEV;
+
+	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
+	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
+	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
+	dln2->interface = interface;
+	usb_set_intfdata(interface, dln2);
+	init_waitqueue_head(&dln2->disconnect_wq);
+
+	for (i = 0; i < DLN2_HANDLES; i++) {
+		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
+		spin_lock_init(&dln2->mod_rx_slots[i].lock);
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
+			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
+	}
+
+	spin_lock_init(&dln2->event_cb_lock);
+	spin_lock_init(&dln2->disconnect_lock);
+	INIT_LIST_HEAD(&dln2->event_cb_list);
+
+	ret = dln2_setup_rx_urbs(dln2, hostif);
+	if (ret)
+		goto out_cleanup;
+
+	ret = dln2_hw_init(dln2);
+	if (ret < 0) {
+		dev_err(dev, "failed to initialize hardware\n");
+		goto out_cleanup;
+	}
+
+	ret = mfd_add_hotplug_devices(dev, dln2_devs, ARRAY_SIZE(dln2_devs));
+	if (ret != 0) {
+		dev_err(dev, "failed to add mfd devices to core\n");
+		goto out_cleanup;
+	}
+
+	return 0;
+
+out_cleanup:
+	dln2_free(dln2);
+
+	return ret;
+}
+
+static const struct usb_device_id dln2_table[] = {
+	{ USB_DEVICE(0xa257, 0x2013) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, dln2_table);
+
+static struct usb_driver dln2_driver = {
+	.name = "dln2",
+	.probe = dln2_probe,
+	.disconnect = dln2_disconnect,
+	.id_table = dln2_table,
+};
+
+module_usb_driver(dln2_driver);
+
+MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
+MODULE_DESCRIPTION("Core driver for the Diolan DLN2 interface adapter");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
new file mode 100644
index 0000000..57ddc58
--- /dev/null
+++ b/include/linux/mfd/dln2.h
@@ -0,0 +1,69 @@ 
+#ifndef __LINUX_USB_DLN2_H
+#define __LINUX_USB_DLN2_H
+
+#define DLN2_CMD(cmd, id)		((cmd) | ((id) << 8))
+
+struct dln2_platform_data {
+	u16 handle;		/* sub-driver handle (internally used only) */
+	u8 port;		/* I2C/SPI port */
+};
+
+/**
+ * dln2_event_cb_t - event callback function signature
+ *
+ * @pdev - the sub-device that registered this callback
+ * @echo - the echo header field received in the message
+ * @data - the data payload
+ * @len  - the data payload length
+ *
+ * The callback function is called in interrupt context and the data
+ * payload is only valid during the call. If the user needs later
+ * access of the data, it must copy it.
+ */
+
+typedef void (*dln2_event_cb_t)(struct platform_device *pdev, u16 echo,
+				const void *data, int len);
+
+/**
+ * dl2n_register_event_cb - register a callback function for an event
+ *
+ * @pdev - the sub-device that registers the callback
+ * @event - the event for which to register a callback
+ * @event_cb - the callback function
+ *
+ * @return 0 in case of success, negative value in case of error
+ */
+int dln2_register_event_cb(struct platform_device *pdev, u16 event,
+			   dln2_event_cb_t event_cb);
+
+/**
+ * dln2_unregister_event_cb - unregister the callback function for an event
+ *
+ * @pdev - the sub-device that registered the callback
+ * @event - the event for which to register a callback
+ */
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 event);
+
+/**
+ * dln2_transfer - issue a DLN2 command and wait for a response and
+ * the associated data
+ *
+ * @pdev - the sub-device which is issuing this transfer
+ * @cmd - the command to be sent to the device
+ * @obuf - the buffer to be sent to the device; it can be NULL if the
+ *	user doesn't need to transmit data with this command
+ * @obuf_len - the size of the buffer to be sent to the device
+ * @ibuf - any data associated with the response will be copied here;
+ *	it can be NULL if the user doesn't need the response data
+ * @ibuf_len - must be initialized to the input buffer size; it will
+ *	be modified to indicate the actual data transfered;
+ * @result - pointer to store the result code received from hardware;
+ *	it can be NULL if the user doesn't need the result code
+ *
+ * @return 0 for success, negative value for errors
+ */
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len, u16 *result);
+
+#endif