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Date: Wed, 11 Nov 2015 21:03:14 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Dave Penkler <dpenkler@...il.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
peter.chen@...escale.com, teuniz@...il.com,
USB <linux-usb@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
dpenkler@...il.org
Subject: Re: [PATCH v3 1/5] Implement an ioctl to support the USMTMC-USB488
READ_STATUS_BYTE operation.
On Wed, Nov 11, 2015 at 1:16 PM, Dave Penkler <dpenkler@...il.com> wrote:
> Background:
> When performing a read on an instrument that is executing a function
> that runs longer than the USB timeout the instrument may hang and require
> a device reset to recover. The READ_STATUS_BYTE operation always returns
> even when the instrument is busy permitting to poll for the appropriate
> condition. This capability is refered to in instrument application notes
> on synchronizing acquisitions for other platforms.
>
Won't comment precisely by line, but common nitpicks about style:
- added empty lines where no need
- redundant parens
- pieces of code takes whole line when they are quite fit tail of previous one.
And why malloc for 8 bytes?
> Signed-off-by: Dave Penkler <dpenkler@...il.com>
> ---
> drivers/usb/class/usbtmc.c | 223 +++++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/usb/tmc.h | 2 +
> 2 files changed, 225 insertions(+)
>
> diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
> index 7a11a82..c1593e7 100644
> --- a/drivers/usb/class/usbtmc.c
> +++ b/drivers/usb/class/usbtmc.c
> @@ -87,6 +87,20 @@ struct usbtmc_device_data {
> u8 bTag_last_write; /* needed for abort */
> u8 bTag_last_read; /* needed for abort */
>
> +
> + /* data for interrupt in endpoint handling */
> + u8 bNotify1;
> + u8 bNotify2;
> + u16 ifnum;
> + u8 iin_bTag;
> + u8 *iin_buffer;
> + atomic_t iin_data_valid;
> + unsigned int iin_ep;
> + int iin_ep_present;
> + int iin_interval;
> + struct urb *iin_urb;
> + u16 iin_wMaxPacketSize;
> +
> u8 rigol_quirk;
>
> /* attributes from the USB TMC spec for this device */
> @@ -99,6 +113,7 @@ struct usbtmc_device_data {
> struct usbtmc_dev_capabilities capabilities;
> struct kref kref;
> struct mutex io_mutex; /* only one i/o function running at a time */
> + wait_queue_head_t waitq;
> };
> #define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
>
> @@ -373,6 +388,91 @@ exit:
> return rv;
> }
>
> +static int usbtmc488_ioctl_read_stb(struct usbtmc_device_data *data,
> + unsigned long arg)
> +{
> + u8 *buffer;
> + struct device *dev;
> + int rv;
> + u8 tag, stb;
> +
> + dev = &data->intf->dev;
> +
> + dev_dbg(dev, "Enter ioctl_read_stb iin_ep_present: %d\n",
> + data->iin_ep_present);
> +
> + buffer = kmalloc(8, GFP_KERNEL);
> + if (!buffer)
> + return -ENOMEM;
> +
> +
> + atomic_set(&data->iin_data_valid, 0);
> +
> + rv = usb_control_msg(data->usb_dev,
> + usb_rcvctrlpipe(data->usb_dev, 0),
> + USBTMC488_REQUEST_READ_STATUS_BYTE,
> + USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
> + data->iin_bTag,
> + data->ifnum,
> + buffer, 0x03, USBTMC_TIMEOUT);
> +
> + if (rv < 0) {
> + dev_err(dev, "stb usb_control_msg returned %d\n", rv);
> + goto exit;
> + }
> +
> + if (buffer[0] != USBTMC_STATUS_SUCCESS) {
> + dev_err(dev, "control status returned %x\n",
> + buffer[0]);
> + rv = -EIO;
> + goto exit;
> + }
> +
> + if (data->iin_ep_present) {
> +
> + rv = wait_event_interruptible_timeout(
> + data->waitq,
> + (atomic_read(&data->iin_data_valid) != 0),
> + USBTMC_TIMEOUT
> + );
> +
> + if (rv < 0) {
> + dev_dbg(dev, "wait interrupted %d\n", rv);
> + goto exit;
> + }
> +
> + if (rv == 0) {
> + dev_dbg(dev, "wait timed out\n");
> + rv = -ETIME;
> + goto exit;
> + }
> +
> + tag = data->bNotify1 & 0x7f;
> +
> + if (tag != data->iin_bTag) {
> + dev_err(dev, "expected bTag %x got %x\n",
> + data->iin_bTag, tag);
> + }
> +
> + stb = data->bNotify2;
> + } else {
> + stb = buffer[2];
> + }
> +
> + rv = copy_to_user((void __user *)arg, &stb, sizeof(stb));
> + if (rv)
> + rv = -EFAULT;
> +
> + exit:
> + /* bump interrupt bTag */
> + data->iin_bTag += 1;
> + if (data->iin_bTag > 127)
> + data->iin_bTag = 2;
> +
> + kfree(buffer);
> + return rv;
> +}
> +
> /*
> * Sends a REQUEST_DEV_DEP_MSG_IN message on the Bulk-IN endpoint.
> * @transfer_size: number of bytes to request from the device.
> @@ -1069,6 +1169,11 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> case USBTMC_IOCTL_ABORT_BULK_IN:
> retval = usbtmc_ioctl_abort_bulk_in(data);
> break;
> +
> + case USBTMC488_IOCTL_READ_STB:
> + retval = usbtmc488_ioctl_read_stb(data, arg);
> + break;
> +
> }
>
> skip_io_on_zombie:
> @@ -1092,6 +1197,69 @@ static struct usb_class_driver usbtmc_class = {
> .minor_base = USBTMC_MINOR_BASE,
> };
>
> +static void usbtmc_interrupt(struct urb *urb)
> +{
> + struct usbtmc_device_data *data = urb->context;
> + int status = urb->status;
> + int rv;
> +
> + dev_dbg(&data->intf->dev, "int status: %d len %d\n",
> + status, urb->actual_length);
> +
> + switch (status) {
> + case 0: /* SUCCESS */
> +
> + if (data->iin_buffer[0] & 0x80) {
> + /* check for valid STB notification */
> + if ((data->iin_buffer[0] & 0x7f) > 1) {
> + data->bNotify1 = data->iin_buffer[0];
> + data->bNotify2 = data->iin_buffer[1];
> + atomic_set(&data->iin_data_valid, 1);
> + wake_up_interruptible(&data->waitq);
> + goto exit;
> + }
> + }
> + dev_warn(&data->intf->dev, "invalid notification: %x\n",
> + data->iin_buffer[0]);
> + break;
> + case -EOVERFLOW:
> + dev_err(&data->intf->dev,
> + "%s - overflow with length %d, actual length is %d\n",
> + __func__, data->iin_wMaxPacketSize, urb->actual_length);
> + case -ECONNRESET:
> + case -ENOENT:
> + case -ESHUTDOWN:
> + case -EILSEQ:
> + case -ETIME:
> + /* urb terminated, clean up */
> + dev_dbg(&data->intf->dev,
> + "%s - urb terminated, status: %d\n",
> + __func__, status);
> + return;
> + default:
> + dev_err(&data->intf->dev,
> + "%s - unknown status received: %d\n",
> + __func__, status);
> + }
> +exit:
> + rv = usb_submit_urb(urb, GFP_ATOMIC);
> + if (rv) {
> + dev_err(&data->intf->dev, "%s - usb_submit_urb failed: %d\n",
> + __func__, rv);
> + }
> +}
> +
> +static void usbtmc_free_int(struct usbtmc_device_data *data)
> +{
> + if (data->iin_ep_present) {
> + if (data->iin_urb) {
> + usb_kill_urb(data->iin_urb);
> + kfree(data->iin_buffer);
> + usb_free_urb(data->iin_urb);
> + kref_put(&data->kref, usbtmc_delete);
> + }
> + }
> +}
>
> static int usbtmc_probe(struct usb_interface *intf,
> const struct usb_device_id *id)
> @@ -1114,6 +1282,8 @@ static int usbtmc_probe(struct usb_interface *intf,
> usb_set_intfdata(intf, data);
> kref_init(&data->kref);
> mutex_init(&data->io_mutex);
> + init_waitqueue_head(&data->waitq);
> + atomic_set(&data->iin_data_valid, 0);
> data->zombie = 0;
>
> /* Determine if it is a Rigol or not */
> @@ -1134,9 +1304,12 @@ static int usbtmc_probe(struct usb_interface *intf,
> data->bTag = 1;
> data->TermCharEnabled = 0;
> data->TermChar = '\n';
> + /* 2 <= bTag <= 127 USBTMC-USB488 subclass specification 4.3.1 */
> + data->iin_bTag = 2;
>
> /* USBTMC devices have only one setting, so use that */
> iface_desc = data->intf->cur_altsetting;
> + data->ifnum = iface_desc->desc.bInterfaceNumber;
>
> /* Find bulk in endpoint */
> for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
> @@ -1161,6 +1334,20 @@ static int usbtmc_probe(struct usb_interface *intf,
> break;
> }
> }
> + /* Find int endpoint */
> + for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
> + endpoint = &iface_desc->endpoint[n].desc;
> +
> + if (usb_endpoint_is_int_in(endpoint)) {
> + data->iin_ep_present = 1;
> + data->iin_ep = endpoint->bEndpointAddress;
> + data->iin_wMaxPacketSize = usb_endpoint_maxp(endpoint);
> + data->iin_interval = endpoint->bInterval;
> + dev_dbg(&intf->dev, "Found Int in endpoint at %u\n",
> + data->iin_ep);
> + break;
> + }
> + }
>
> retcode = get_capabilities(data);
> if (retcode)
> @@ -1169,6 +1356,40 @@ static int usbtmc_probe(struct usb_interface *intf,
> retcode = sysfs_create_group(&intf->dev.kobj,
> &capability_attr_grp);
>
> +
> + if (data->iin_ep_present) {
> + /* allocate int urb */
> + data->iin_urb = usb_alloc_urb(0, GFP_KERNEL);
> + if (!data->iin_urb) {
> + dev_err(&intf->dev, "Failed to allocate int urb\n");
> + goto error_register;
> + }
> +
> + /* will reference data in int urb */
> + kref_get(&data->kref);
> +
> + /* allocate buffer for interrupt in */
> + data->iin_buffer = kmalloc(data->iin_wMaxPacketSize,
> + GFP_KERNEL);
> + if (!data->iin_buffer) {
> + dev_err(&intf->dev, "Failed to allocate int buf\n");
> + goto error_register;
> + }
> +
> + /* fill interrupt urb */
> + usb_fill_int_urb(data->iin_urb, data->usb_dev,
> + usb_rcvintpipe(data->usb_dev, data->iin_ep),
> + data->iin_buffer, data->iin_wMaxPacketSize,
> + usbtmc_interrupt,
> + data, data->iin_interval);
> +
> + if (usb_submit_urb(data->iin_urb, GFP_KERNEL)) {
> + retcode = -EIO;
> + dev_err(&intf->dev, "Failed to submit iin_urb\n");
> + goto error_register;
> + }
> + }
> +
> retcode = sysfs_create_group(&intf->dev.kobj, &data_attr_grp);
>
> retcode = usb_register_dev(intf, &usbtmc_class);
> @@ -1185,6 +1406,7 @@ static int usbtmc_probe(struct usb_interface *intf,
> error_register:
> sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
> sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
> + usbtmc_free_int(data);
> kref_put(&data->kref, usbtmc_delete);
> return retcode;
> }
> @@ -1196,6 +1418,7 @@ static void usbtmc_disconnect(struct usb_interface *intf)
> dev_dbg(&intf->dev, "usbtmc_disconnect called\n");
>
> data = usb_get_intfdata(intf);
> + usbtmc_free_int(data);
> usb_deregister_dev(intf, &usbtmc_class);
> sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
> sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
> diff --git a/include/uapi/linux/usb/tmc.h b/include/uapi/linux/usb/tmc.h
> index c045ae1..49060ea 100644
> --- a/include/uapi/linux/usb/tmc.h
> +++ b/include/uapi/linux/usb/tmc.h
> @@ -30,6 +30,7 @@
> #define USBTMC_REQUEST_CHECK_CLEAR_STATUS 6
> #define USBTMC_REQUEST_GET_CAPABILITIES 7
> #define USBTMC_REQUEST_INDICATOR_PULSE 64
> +#define USBTMC488_REQUEST_READ_STATUS_BYTE 128
>
> /* Request values for USBTMC driver's ioctl entry point */
> #define USBTMC_IOC_NR 91
> @@ -39,5 +40,6 @@
> #define USBTMC_IOCTL_ABORT_BULK_IN _IO(USBTMC_IOC_NR, 4)
> #define USBTMC_IOCTL_CLEAR_OUT_HALT _IO(USBTMC_IOC_NR, 6)
> #define USBTMC_IOCTL_CLEAR_IN_HALT _IO(USBTMC_IOC_NR, 7)
> +#define USBTMC488_IOCTL_READ_STB _IOR(USBTMC_IOC_NR, 18, unsigned char)
>
> #endif
> --
> 2.5.1
> --
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--
With Best Regards,
Andy Shevchenko
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