USB: usbtmc: TMC request code segregated from usbtmc_read

These patches implement a modification of the USBTMC
protocol to allow operation with Rigol equipment. The TMC request portion of
the code in function usbtmc_read is segregated to a function
send_request_dev_dep_msg_in as implemented by tommie in
https://github.com/tommie/linux/blob/usbtmc-rigol/drivers/usb/class/usbtmc.c
allowing the reuse later.

Signed-off-by: Alexandre Peixoto Ferreira <alexandref75@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 54 insertions, 31 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index c450b047e365..9c370427d2ef 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -375,6 +375,59 @@ exit:
         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.
+ *
+ * See the USBTMC specification, Table 4.
+ *
+ * Also updates bTag_last_write.
+ */
+static int send_request_dev_dep_msg_in(struct usbtmc_device_data *data, size_t transfer_size)
+{
+        int retval;
+        u8 buffer[USBTMC_HEADER_SIZE];
+        int actual;
+
+        /* Setup IO buffer for REQUEST_DEV_DEP_MSG_IN message
+         * Refer to class specs for details
+         */
+        buffer[0] = 2;
+        buffer[1] = data->bTag;
+        buffer[2] = ~(data->bTag);
+        buffer[3] = 0; /* Reserved */
+        buffer[4] = (transfer_size) & 255;
+        buffer[5] = ((transfer_size) >> 8) & 255;
+        buffer[6] = ((transfer_size) >> 16) & 255;
+        buffer[7] = ((transfer_size) >> 24) & 255;
+        buffer[8] = data->TermCharEnabled * 2;
+        /* Use term character? */
+        buffer[9] = data->TermChar;
+        buffer[10] = 0; /* Reserved */
+        buffer[11] = 0; /* Reserved */
+
+        /* Send bulk URB */
+        retval = usb_bulk_msg(data->usb_dev,
+                              usb_sndbulkpipe(data->usb_dev,
+                                              data->bulk_out),
+                              buffer, USBTMC_HEADER_SIZE, &actual, USBTMC_TIMEOUT);
+
+        /* Store bTag (in case we need to abort) */
+        data->bTag_last_write = data->bTag;
+
+        /* Increment bTag -- and increment again if zero */
+        data->bTag++;
+        if (!data->bTag)
+                (data->bTag)++;
+
+        if (retval < 0) {
+                dev_err(&data->intf->dev, "usb_bulk_msg in send_request_dev_dep_msg_in() returned %d\n", retval);
+                return retval;
+        }
+
+        return 0;
+}
+
 static ssize_t usbtmc_read(struct file *filp, char __user *buf,
                            size_t count, loff_t *f_pos)
 {
@@ -411,37 +464,7 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
                 else
                         this_part = remaining;
 
-                /* Setup IO buffer for DEV_DEP_MSG_IN message
-                 * Refer to class specs for details
-                 */
-                buffer[0] = 2;
-                buffer[1] = data->bTag;
-                buffer[2] = ~(data->bTag);
-                buffer[3] = 0; /* Reserved */
-                buffer[4] = (this_part) & 255;
-                buffer[5] = ((this_part) >> 8) & 255;
-                buffer[6] = ((this_part) >> 16) & 255;
-                buffer[7] = ((this_part) >> 24) & 255;
-                buffer[8] = data->TermCharEnabled * 2;
-                /* Use term character? */
-                buffer[9] = data->TermChar;
-                buffer[10] = 0; /* Reserved */
-                buffer[11] = 0; /* Reserved */
-
-                /* Send bulk URB */
-                retval = usb_bulk_msg(data->usb_dev,
-                                      usb_sndbulkpipe(data->usb_dev,
-                                                      data->bulk_out),
-                                      buffer, 12, &actual, USBTMC_TIMEOUT);
-
-                /* Store bTag (in case we need to abort) */
-                data->bTag_last_write = data->bTag;
-
-                /* Increment bTag -- and increment again if zero */
-                data->bTag++;
-                if (!data->bTag)
-                        (data->bTag)++;
-
+                        retval = send_request_dev_dep_msg_in(data, this_part);
                 if (retval < 0) {
                         dev_err(dev, "usb_bulk_msg returned %d\n", retval);
                         if (data->auto_abort)