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SubjectRe: [PATCH v6 1/4] mfd: add support for Diolan DLN-2 devices
On Thu, Sep 25, 2014 at 07:07:31PM +0300, Octavian Purdila wrote:
> 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 | 9 +
> drivers/mfd/Makefile | 1 +
> drivers/mfd/dln2.c | 751 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/dln2.h | 67 +++++
> 4 files changed, 828 insertions(+)
> create mode 100644 drivers/mfd/dln2.c
> create mode 100644 include/linux/mfd/dln2.h

[...]

> +#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,

This is the only handle that was fixed (0), right? Initialise this one
explicitly in case any one ever tries to reorder them.

> + 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 */
> + unsigned long bmap;
> +
> + /* 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;
> + unsigned long flags;
> + int ret = 0;
> +
> + new = kmalloc(sizeof(*new), GFP_KERNEL);
> + if (!new)
> + return -ENOMEM;
> +
> + new->id = id;
> + new->callback = rx_cb;
> + new->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->list, &dln2->event_cb_list);
> +
> + spin_unlock_irqrestore(&dln2->event_cb_lock, flags);
> +
> + if (ret)
> + kfree(new);
> +
> + 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 int dln2_submit_urb(struct dln2_dev *dln2, struct urb *urb, gfp_t gfp)
> +{
> + int ret;
> + struct device *dev = &dln2->interface->dev;
> +
> + ret = usb_submit_urb(urb, gfp);
> + if (ret < 0)
> + dev_err(dev, "failed to (re)submit RX URB: %d\n", ret);
> + return ret;
> +}
> +
> +static void 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;
> + struct device *dev = &dln2->interface->dev;
> +
> + spin_lock(&rxs->lock);
> +
> + rxc = &rxs->slots[rx_slot];

This can be done outside the lock, right?

> +
> + if (rxc->in_use && !rxc->urb) {
> + rxc->urb = urb;
> + complete(&rxc->done);
> + /* URB will be resubmitted in free_rx_slot */
> + } else {
> + dev_warn(dev, "bad/late response %d/%d\n", handle, rx_slot);
> + dln2_submit_urb(dln2, urb, GFP_ATOMIC);

And so can the resubmission.

I think this might be easier to follow if you just do this inline in the
completion handler, and always resubmit there before returning (unless
the slot is in use).

> + }
> +
> + spin_unlock(&rxs->lock);
> +}
> +
> +static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
> + void *data, int len)

Rename this one dln2_run_event_callbacks to match your new names (much
better by the way)?

> +{
> + 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;
> +
> + 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_rx_callbacks(dln2, id, echo, data, len);
> + } else {
> + dln2_rx_transfer(dln2, urb, handle, echo);
> + /* URB will be re-submitted in dln2_rx_transfer */

This comment is a little misleading since the urb will not be
resubmitted if the corresponding slot is in use. See my comment to
dln2_rx_transfer above.

> + return;
> + }
> +
> +out:
> + dln2_submit_urb(dln2, urb, GFP_ATOMIC);
> +}
> +
> +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;
> +

You could still check the global disconnect flag here to speed up
disconnect (locking not needed). Return -ENODEV as I mentioned earlier.

> + 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)
> + dln2_submit_urb(dln2, urb, GFP_KERNEL);
> +
> + 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)
> +{
> + int ret = 0;
> + u16 result;
> + int rx_slot;
> + struct dln2_response *rsp;
> + struct dln2_rx_context *rxc;
> + struct device *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;
> + }
> +
> + dev = &dln2->interface->dev;

This can be done when declaring dev.

> +
> + 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 (!rxc->urb) {
> + ret = -ENODEV;
> + goto out_free_rx_slot;
> + }

This can only happen if disconnected, right? Perhaps add a comment
unless you want to the test the disconnected flag instead which would
make it self-explanatory.

> +
> + /* 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;
> + }
> +
> + result = le16_to_cpu(rsp->result);
> + if (result) {
> + dev_dbg(dev, "%d received response with error %d\n",
> + handle, 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;
> +}
v> +
> +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> + const void *obuf, unsigned obuf_len,
> + void *ibuf, unsigned *ibuf_len)
> +{
> + struct dln2_platform_data *dln2_pdata;
> + struct dln2_dev *dln2;
> + u16 h;
> +
> + dln2 = dev_get_drvdata(pdev->dev.parent);
> + dln2_pdata = dev_get_platdata(&pdev->dev);
> + h = dln2_pdata->handle;
> +
> + return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
> +}
> +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);
> + 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);
> + 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;
> +
> + 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 = dln2_submit_urb(dln2, dln2->rx_urb[i], GFP_KERNEL);
> + if (ret < 0)
> + return ret;

Is it really worth having this helper only to save a couple of lines on
a dev_err? If you do all resubmissions on completion inline in the
handler, you only have three places where usb_submit_urb is called.

> + }
> +
> + 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;
> + int id;
> +
> + 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);
> + INIT_LIST_HEAD(&dln2->event_cb_list);
> +
> + ret = dln2_setup_rx_urbs(dln2, hostif);
> + if (ret) {
> + dln2_free(dln2);

goto out_cleanup as mentioned earlier.

> + return ret;
> + }
> +
> + ret = dln2_hw_init(dln2);
> + if (ret < 0) {
> + dev_err(dev, "failed to initialize hardware\n");
> + goto out_cleanup;
> + }
> +
> + id = dln2->usb_dev->bus->busnum << 8 | dln2->usb_dev->devnum;

After giving this some more thought, I think you should just
use PLATFORM_DEVID_AUTO as id. I have submitted a series to fix the
other USB MFD drivers and add a convenience helper to register
hotpluggable MFDs here:

http://marc.info/?l=linux-kernel&m=141172912516884&w=2

> + ret = mfd_add_devices(dev, id, dln2_devs, ARRAY_SIZE(dln2_devs),
> + NULL, 0, NULL);
> + 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;
> +}

I'll try to take a quick look on the subdrivers on Monday.

Johan


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