Commit c82c6d45 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: pl2303: refactor baud-rate divisor handling 



Refactor baud-rate divisor handling.

Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 871996ed

drivers/usb/serial/pl2303.c

+25 −16
Original line number Diff line number Diff line
@@ -339,6 +339,28 @@ static speed_t pl2303_get_supported_baud_rate(speed_t baud) 
	return baud;

}



static speed_t pl2303_encode_baud_rate_divisor(unsigned char buf[4],

								speed_t baud)

{

	unsigned int tmp;



	/*

	 * Apparently the formula is:

	 * baudrate = 12M * 32 / (2^buf[1]) / buf[0]

	 */

	tmp = 12000000 * 32 / baud;

	buf[3] = 0x80;

	buf[2] = 0;

	buf[1] = (tmp >= 256);

	while (tmp >= 256) {

		tmp >>= 2;

		buf[1] <<= 1;

	}

	buf[0] = tmp;



	return baud;

}



static void pl2303_encode_baud_rate(struct tty_struct *tty,

					struct usb_serial_port *port,

					u8 buf[4])
@@ -362,23 +384,10 @@ static void pl2303_encode_baud_rate(struct tty_struct *tty, 
	 */

	baud = pl2303_get_supported_baud_rate(baud);



	if (baud <= 115200) {

	if (baud <= 115200)

		put_unaligned_le32(baud, buf);

	} else {

		/*

		 * Apparently the formula for higher speeds is:

		 * baudrate = 12M * 32 / (2^buf[1]) / buf[0]

		 */

		unsigned tmp = 12000000 * 32 / baud;

		buf[3] = 0x80;

		buf[2] = 0;

		buf[1] = (tmp >= 256);

		while (tmp >= 256) {

			tmp >>= 2;

			buf[1] <<= 1;

		}

		buf[0] = tmp;

	}

	else

		baud = pl2303_encode_baud_rate_divisor(buf, baud);



	/* Save resulting baud rate */

	tty_encode_baud_rate(tty, baud, baud);