Commit 492896f0 authored by Tim Small's avatar Tim Small Committed by Greg Kroah-Hartman
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USb: Break support for WinChipHead CH341 340 USB->Serial "chip" 



Here is a patch to the ch341 driver which adds serial break support.

Signed-off-by: default avatarTim Small <tim@seoss.co.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 823c3fd9

drivers/usb/serial/ch341.c

+52 −0
Original line number Diff line number Diff line
@@ -56,6 +56,18 @@ 
#define CH341_BAUDBASE_FACTOR 1532620800

#define CH341_BAUDBASE_DIVMAX 3



/* Break support - the information used to implement this was gleaned from

 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.

 */



#define CH341_REQ_WRITE_REG    0x9A

#define CH341_REQ_READ_REG     0x95

#define CH341_REG_BREAK1       0x05

#define CH341_REG_BREAK2       0x18

#define CH341_NBREAK_BITS_REG1 0x01

#define CH341_NBREAK_BITS_REG2 0x40





static int debug;



static struct usb_device_id id_table [] = {
@@ -373,6 +385,45 @@ static void ch341_set_termios(struct tty_struct *tty, 
	 */

}



static void ch341_break_ctl(struct tty_struct *tty, int break_state)

{

	const uint16_t ch341_break_reg =

		CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);

	struct usb_serial_port *port = tty->driver_data;

	int r;

	uint16_t reg_contents;

	uint8_t break_reg[2];



	dbg("%s()", __func__);



	r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,

			ch341_break_reg, 0, break_reg, sizeof(break_reg));

	if (r < 0) {

		printk(KERN_WARNING "%s: USB control read error whilst getting"

				" break register contents.\n", __FILE__);

		return;

	}

	dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",

			__func__, break_reg[0], break_reg[1]);

	if (break_state != 0) {

		dbg("%s - Enter break state requested", __func__);

		break_reg[0] &= ~CH341_NBREAK_BITS_REG1;

		break_reg[1] &= ~CH341_NBREAK_BITS_REG2;

	} else {

		dbg("%s - Leave break state requested", __func__);

		break_reg[0] |= CH341_NBREAK_BITS_REG1;

		break_reg[1] |= CH341_NBREAK_BITS_REG2;

	}

	dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",

			__func__, break_reg[0], break_reg[1]);

	reg_contents = (uint16_t)break_reg[0] | ((uint16_t)break_reg[1] << 8);

	r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,

			ch341_break_reg, reg_contents);

	if (r < 0)

		printk(KERN_WARNING "%s: USB control write error whilst setting"

				" break register contents.\n", __FILE__);

}



static int ch341_tiocmset(struct tty_struct *tty, struct file *file,

			  unsigned int set, unsigned int clear)

{
@@ -576,6 +627,7 @@ static struct usb_serial_driver ch341_device = { 
	.close             = ch341_close,

	.ioctl             = ch341_ioctl,

	.set_termios       = ch341_set_termios,

	.break_ctl         = ch341_break_ctl,

	.tiocmget          = ch341_tiocmget,

	.tiocmset          = ch341_tiocmset,

	.read_int_callback = ch341_read_int_callback,