usb: usbtmc: Add ioctl for vendor specific write

The new ioctl USBTMC_IOCTL_WRITE sends a generic message to bulk OUT. This ioctl is used for vendor specific or asynchronous I/O as well.

The message is split into chunks of 4k (page size). Message size is aligned to 32 bit boundaries.

With flag USBTMC_FLAG_ASYNC the ioctl is non blocking. With flag USBTMC_FLAG_APPEND additional urbs are queued and out_status/out_transfer_size is not reset. EPOLLOUT | EPOLLWRNORM is signaled when all submitted urbs are completed.

Flush flying urbs when file handle is closed or device is suspended or reset.

Signed-off-by Guido Kiener <[email protected]>

Reviewed-by Steve Bayless <[email protected]>

---
 drivers/usb/class/usbtmc.c   | 416 ++++++++++++++++++++++++++++++++++-
 include/uapi/linux/usb/tmc.h |  14 ++
 2 files changed, 428 insertions(+), 2 deletions(-)

drivers/usb/class/usbtmc.c +12 -0

index 846599dd0c84..c46280f53f39 100644
@@ -37,6 +37,8 @@
 /* Default USB timeout (in milliseconds) */
 #define USBTMC_TIMEOUT		5000
 
+/* Max number of urbs used in write transfers */
+#define MAX_URBS_IN_FLIGHT	16
 /* I/O buffer size used in generic read/write functions */
 #define USBTMC_BUFSIZE		(4096)
 

@@ -125,9 +127,19 @@ struct usbtmc_file_data {
 	u32            timeout;
 	u8             srq_byte;
 	atomic_t       srq_asserted;
+
 	u8             eom_val;
 	u8             term_char;
 	bool           term_char_enabled;
+
+	spinlock_t     err_lock; /* lock for errors */
+
+	struct usb_anchor submitted;
+
+	/* data for generic_write */
+	struct semaphore limit_write_sem;
+	u32 out_transfer_size;
+	int out_status;
 };
 
 #ifdef CONFIG_COMPAT