USB: ftdi_sio: clean up SIO write support

The original SIO devices require a control byte for every packet
written. Clean up the unnecessarily messy implementation of this.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index a41974e..f515f32 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -71,10 +71,6 @@ struct ftdi_private {
                                /* the last data state set - needed for doing
                                 * a break
                                 */
-       int write_offset;       /* This is the offset in the usb data block to
-                                * write the serial data - it varies between
-                                * devices
-                                */
        int flags;              /* some ASYNC_xxxx flags are supported */
        unsigned long last_dtr_rts;     /* saved modem control outputs */
        wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
@@ -1279,7 +1275,6 @@ static void ftdi_determine_type(struct usb_serial_port *port)
 
        /* Assume it is not the original SIO device for now. */
        priv->baud_base = 48000000 / 2;
-       priv->write_offset = 0;
 
        version = le16_to_cpu(udev->descriptor.bcdDevice);
        interfaces = udev->actconfig->desc.bNumInterfaces;
@@ -1321,7 +1316,6 @@ static void ftdi_determine_type(struct usb_serial_port *port)
                /* Old device.  Assume it's the original SIO. */
                priv->chip_type = SIO;
                priv->baud_base = 12000000 / 16;
-               priv->write_offset = 1;
        } else if (version < 0x400) {
                /* Assume it's an FT8U232AM (or FT8U245AM) */
                /* (It might be a BM because of the iSerialNumber bug,
@@ -1757,50 +1751,29 @@ static int ftdi_prepare_write_buffer(struct usb_serial_port *port,
 {
        struct ftdi_private *priv;
        unsigned char *buffer;
-       int data_offset ;       /* will be 1 for the SIO and 0 otherwise */
-       int transfer_size;
+       int len;
 
        priv = usb_get_serial_port_data(port);
 
-       data_offset = priv->write_offset;
-       dbg("data_offset set to %d", data_offset);
+       len = count;
+       if (priv->chip_type == SIO && count != 0)
+               len += ((count - 1) / (priv->max_packet_size - 1)) + 1;
 
-       /* Determine total transfer size */
-       transfer_size = count;
-       if (data_offset > 0) {
-               /* Original sio needs control bytes too... */
-               transfer_size += (data_offset *
-                               ((count + (priv->max_packet_size - 1 - data_offset)) /
-                                (priv->max_packet_size - data_offset)));
-       }
-
-       buffer = kmalloc(transfer_size, GFP_ATOMIC);
+       buffer = kmalloc(len, GFP_ATOMIC);
        if (!buffer) {
                dev_err(&port->dev, "%s - could not allocate buffer\n",
                                __func__);
                return -ENOMEM;
        }
 
-       /* Copy data */
-       if (data_offset > 0) {
-               /* Original sio requires control byte at start of
-                  each packet. */
-               int user_pktsz = priv->max_packet_size - data_offset;
-               int todo = count;
-               unsigned char *first_byte = buffer;
-               const unsigned char *current_position = src;
-
-               while (todo > 0) {
-                       if (user_pktsz > todo)
-                               user_pktsz = todo;
-                       /* Write the control byte at the front of the packet*/
-                       *first_byte = 1 | ((user_pktsz) << 2);
-                       /* Copy data for packet */
-                       memcpy(first_byte + data_offset,
-                               current_position, user_pktsz);
-                       first_byte += user_pktsz + data_offset;
-                       current_position += user_pktsz;
-                       todo -= user_pktsz;
+       if (priv->chip_type == SIO) {
+               int i, msg_len;
+
+               for (i = 0; i < len; i += priv->max_packet_size) {
+                       msg_len = min_t(int, len - i, priv->max_packet_size) - 1;
+                       buffer[i] = (msg_len << 2) + 1;
+                       memcpy(&buffer[i + 1], src, msg_len);
+                       src += msg_len;
                }
        } else {
                memcpy(buffer, src, count);