USB: serial: ch341: add register and USB request definitions

No functional changes, this just gives names to some registers and USB
requests based on Grigori Goronzy's work and WinChipTech's Linux driver
(which reassuringly agree), then uses them in place of magic numbers.
This also renames the misnamed BREAK2 register (actually UART config)
Signed-off-by: Aidan Thornton <makosoft@gmail.com>
Reviewed-by: Grigori Goronzy <greg@chown.ath.cx>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/ch341.c

@@ -61,13 +61,26 @@
  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  */
 
+#define CH341_REQ_READ_VERSION 0x5F
 #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
-
+#define CH341_REQ_SERIAL_INIT  0xA1
+#define CH341_REQ_MODEM_CTRL   0xA4
+
+#define CH341_REG_BREAK        0x05
+#define CH341_REG_LCR          0x18
+#define CH341_NBREAK_BITS      0x01
+
+#define CH341_LCR_ENABLE_RX    0x80
+#define CH341_LCR_ENABLE_TX    0x40
+#define CH341_LCR_MARK_SPACE   0x20
+#define CH341_LCR_PAR_EVEN     0x10
+#define CH341_LCR_ENABLE_PAR   0x08
+#define CH341_LCR_STOP_BITS_2  0x04
+#define CH341_LCR_CS8          0x03
+#define CH341_LCR_CS7          0x02
+#define CH341_LCR_CS6          0x01
+#define CH341_LCR_CS5          0x00
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x4348, 0x5523) },
@@ -144,16 +157,16 @@ static int ch341_set_baudrate(struct usb_device *dev,
 	a = (factor & 0xff00) | divisor;
 	b = factor & 0xff;
 
-	r = ch341_control_out(dev, 0x9a, 0x1312, a);
+	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a);
 	if (!r)
-		r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
+		r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x0f2c, b);
 
 	return r;
 }
 
 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 {
-	return ch341_control_out(dev, 0xa4, ~control, 0);
+	return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
 }
 
 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
@@ -167,7 +180,7 @@ static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 	if (!buffer)
 		return -ENOMEM;
 
-	r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
+	r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 	if (r < 0)
 		goto out;
 
@@ -197,11 +210,11 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 		return -ENOMEM;
 
 	/* expect two bytes 0x27 0x00 */
-	r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
+	r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 	if (r < 0)
 		goto out;
 
-	r = ch341_control_out(dev, 0xa1, 0, 0);
+	r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 	if (r < 0)
 		goto out;
 
@@ -210,11 +223,11 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 		goto out;
 
 	/* expect two bytes 0x56 0x00 */
-	r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
+	r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
 	if (r < 0)
 		goto out;
 
-	r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
+	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x0050);
 	if (r < 0)
 		goto out;
 
@@ -223,7 +236,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	if (r < 0)
 		goto out;
 
-	r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
+	r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0x501f, 0xd90a);
 	if (r < 0)
 		goto out;
 
@@ -370,7 +383,7 @@ 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 =
-			((uint16_t) CH341_REG_BREAK2 << 8) | CH341_REG_BREAK1;
+			((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 	struct usb_serial_port *port = tty->driver_data;
 	int r;
 	uint16_t reg_contents;
@@ -391,12 +404,12 @@ static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 		__func__, break_reg[0], break_reg[1]);
 	if (break_state != 0) {
 		dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
-		break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
-		break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
+		break_reg[0] &= ~CH341_NBREAK_BITS;
+		break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 	} else {
 		dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
-		break_reg[0] |= CH341_NBREAK_BITS_REG1;
-		break_reg[1] |= CH341_NBREAK_BITS_REG2;
+		break_reg[0] |= CH341_NBREAK_BITS;
+		break_reg[1] |= CH341_LCR_ENABLE_TX;
 	}
 	dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 		__func__, break_reg[0], break_reg[1]);