USB: serial: cp210x: add 16-bit register access functions

cp210x_get_config and cp210x_set_config are cumbersome to use. This change
introduces new register access functions for 16-bit values, instead of
the above functions.

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

1 files changed, 108 insertions, 39 deletions

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 987813b8a7f9..e9b2bddd719f 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -423,14 +423,88 @@ static int cp210x_set_config(struct usb_serial_port *port, u8 request,
 }
 
 /*
- * cp210x_set_config_single
- * Convenience function for calling cp210x_set_config on single data values
- * without requiring an integer pointer
+ * Reads a variable-sized block of CP210X_ registers, identified by req.
+ * Returns data into buf in native USB byte order.
  */
-static inline int cp210x_set_config_single(struct usb_serial_port *port,
-		u8 request, unsigned int data)
+static int cp210x_read_reg_block(struct usb_serial_port *port, u8 req,
+		void *buf, int bufsize)
 {
-	return cp210x_set_config(port, request, &data, 2);
+	struct usb_serial *serial = port->serial;
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	void *dmabuf;
+	int result;
+
+	dmabuf = kmalloc(bufsize, GFP_KERNEL);
+	if (!dmabuf) {
+		/*
+		 * FIXME Some callers don't bother to check for error,
+		 * at least give them consistent junk until they are fixed
+		 */
+		memset(buf, 0, bufsize);
+		return -ENOMEM;
+	}
+
+	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
+			req, REQTYPE_INTERFACE_TO_HOST, 0,
+			port_priv->bInterfaceNumber, dmabuf, bufsize,
+			USB_CTRL_SET_TIMEOUT);
+	if (result == bufsize) {
+		memcpy(buf, dmabuf, bufsize);
+		result = 0;
+	} else {
+		dev_err(&port->dev, "failed get req 0x%x size %d status: %d\n",
+				req, bufsize, result);
+		if (result >= 0)
+			result = -EPROTO;
+
+		/*
+		 * FIXME Some callers don't bother to check for error,
+		 * at least give them consistent junk until they are fixed
+		 */
+		memset(buf, 0, bufsize);
+	}
+
+	kfree(dmabuf);
+
+	return result;
+}
+
+/*
+ * Reads any 16-bit CP210X_ register identified by req.
+ */
+static int cp210x_read_u16_reg(struct usb_serial_port *port, u8 req, u16 *val)
+{
+	__le16 le16_val;
+	int err;
+
+	err = cp210x_read_reg_block(port, req, &le16_val, sizeof(le16_val));
+	if (err)
+		return err;
+
+	*val = le16_to_cpu(le16_val);
+	return 0;
+}
+
+/*
+ * Writes any 16-bit CP210X_ register (req) whose value is passed
+ * entirely in the wValue field of the USB request.
+ */
+static int cp210x_write_u16_reg(struct usb_serial_port *port, u8 req, u16 val)
+{
+	struct usb_serial *serial = port->serial;
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	int result;
+
+	result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
+			req, REQTYPE_HOST_TO_INTERFACE, val,
+			port_priv->bInterfaceNumber, NULL, 0,
+			USB_CTRL_SET_TIMEOUT);
+	if (result < 0) {
+		dev_err(&port->dev, "failed set request 0x%x status: %d\n",
+				req, result);
+	}
+
+	return result;
 }
 
 /*
@@ -442,47 +516,46 @@ static inline int cp210x_set_config_single(struct usb_serial_port *port,
 static int cp210x_detect_swapped_line_ctl(struct usb_serial_port *port)
 {
 	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
-	unsigned int line_ctl_save;
-	unsigned int line_ctl_test;
+	u16 line_ctl_save;
+	u16 line_ctl_test;
 	int err;
 
-	err = cp210x_get_config(port, CP210X_GET_LINE_CTL, &line_ctl_save, 2);
+	err = cp210x_read_u16_reg(port, CP210X_GET_LINE_CTL, &line_ctl_save);
 	if (err)
 		return err;
 
-	line_ctl_test = 0x800;
-	err = cp210x_set_config(port, CP210X_SET_LINE_CTL, &line_ctl_test, 2);
+	err = cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, 0x800);
 	if (err)
 		return err;
 
-	err = cp210x_get_config(port, CP210X_GET_LINE_CTL, &line_ctl_test, 2);
+	err = cp210x_read_u16_reg(port, CP210X_GET_LINE_CTL, &line_ctl_test);
 	if (err)
 		return err;
 
 	if (line_ctl_test == 8) {
 		port_priv->has_swapped_line_ctl = true;
-		line_ctl_save = swab16((u16)line_ctl_save);
+		line_ctl_save = swab16(line_ctl_save);
 	}
 
-	return cp210x_set_config(port, CP210X_SET_LINE_CTL, &line_ctl_save, 2);
+	return cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, line_ctl_save);
 }
 
 /*
- * Must always be called instead of cp210x_get_config(CP210X_GET_LINE_CTL)
+ * Must always be called instead of cp210x_read_u16_reg(CP210X_GET_LINE_CTL)
  * to workaround cp2108 bug and get correct value.
  */
-static int cp210x_get_line_ctl(struct usb_serial_port *port, unsigned int *ctl)
+static int cp210x_get_line_ctl(struct usb_serial_port *port, u16 *ctl)
 {
 	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
 	int err;
 
-	err = cp210x_get_config(port, CP210X_GET_LINE_CTL, ctl, 2);
+	err = cp210x_read_u16_reg(port, CP210X_GET_LINE_CTL, ctl);
 	if (err)
 		return err;
 
 	/* Workaround swapped bytes in 16-bit value from CP210X_GET_LINE_CTL */
 	if (port_priv->has_swapped_line_ctl)
-		*ctl = swab16((u16)(*ctl));
+		*ctl = swab16(*ctl);
 
 	return 0;
 }
@@ -533,8 +606,7 @@ static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
 	int result;
 
-	result = cp210x_set_config_single(port, CP210X_IFC_ENABLE,
-								UART_ENABLE);
+	result = cp210x_write_u16_reg(port, CP210X_IFC_ENABLE, UART_ENABLE);
 	if (result) {
 		dev_err(&port->dev, "%s - Unable to enable UART\n", __func__);
 		return result;
@@ -552,15 +624,12 @@ static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *port)
 
 static void cp210x_close(struct usb_serial_port *port)
 {
-	unsigned int purge_ctl;
-
 	usb_serial_generic_close(port);
 
 	/* Clear both queues; cp2108 needs this to avoid an occasional hang */
-	purge_ctl = PURGE_ALL;
-	cp210x_set_config(port, CP210X_PURGE, &purge_ctl, 2);
+	cp210x_write_u16_reg(port, CP210X_PURGE, PURGE_ALL);
 
-	cp210x_set_config_single(port, CP210X_IFC_ENABLE, UART_DISABLE);
+	cp210x_write_u16_reg(port, CP210X_IFC_ENABLE, UART_DISABLE);
 }
 
 /*
@@ -640,7 +709,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 	struct device *dev = &port->dev;
 	unsigned int cflag, modem_ctl[4];
 	unsigned int baud;
-	unsigned int bits;
+	u16 bits;
 
 	cp210x_get_config(port, CP210X_GET_BAUDRATE, &baud, 4);
 
@@ -673,14 +742,14 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 		cflag |= CS8;
 		bits &= ~BITS_DATA_MASK;
 		bits |= BITS_DATA_8;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits);
 		break;
 	default:
 		dev_dbg(dev, "%s - Unknown number of data bits, using 8\n", __func__);
 		cflag |= CS8;
 		bits &= ~BITS_DATA_MASK;
 		bits |= BITS_DATA_8;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits);
 		break;
 	}
 
@@ -711,7 +780,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 		dev_dbg(dev, "%s - Unknown parity mode, disabling parity\n", __func__);
 		cflag &= ~PARENB;
 		bits &= ~BITS_PARITY_MASK;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits);
 		break;
 	}
 
@@ -723,7 +792,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 	case BITS_STOP_1_5:
 		dev_dbg(dev, "%s - stop bits = 1.5 (not supported, using 1 stop bit)\n", __func__);
 		bits &= ~BITS_STOP_MASK;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits);
 		break;
 	case BITS_STOP_2:
 		dev_dbg(dev, "%s - stop bits = 2\n", __func__);
@@ -732,7 +801,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 	default:
 		dev_dbg(dev, "%s - Unknown number of stop bits, using 1 stop bit\n", __func__);
 		bits &= ~BITS_STOP_MASK;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits);
 		break;
 	}
 
@@ -806,7 +875,7 @@ static void cp210x_set_termios(struct tty_struct *tty,
 {
 	struct device *dev = &port->dev;
 	unsigned int cflag, old_cflag;
-	unsigned int bits;
+	u16 bits;
 	unsigned int modem_ctl[4];
 
 	cflag = tty->termios.c_cflag;
@@ -845,7 +914,7 @@ static void cp210x_set_termios(struct tty_struct *tty,
 			bits |= BITS_DATA_8;
 			break;
 		}
-		if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))
+		if (cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits))
 			dev_dbg(dev, "Number of data bits requested not supported by device\n");
 	}
 
@@ -872,7 +941,7 @@ static void cp210x_set_termios(struct tty_struct *tty,
 				}
 			}
 		}
-		if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))
+		if (cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits))
 			dev_dbg(dev, "Parity mode not supported by device\n");
 	}
 
@@ -886,7 +955,7 @@ static void cp210x_set_termios(struct tty_struct *tty,
 			bits |= BITS_STOP_1;
 			dev_dbg(dev, "%s - stop bits = 1\n", __func__);
 		}
-		if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))
+		if (cp210x_write_u16_reg(port, CP210X_SET_LINE_CTL, bits))
 			dev_dbg(dev, "Number of stop bits requested not supported by device\n");
 	}
 
@@ -926,7 +995,7 @@ static int cp210x_tiocmset(struct tty_struct *tty,
 static int cp210x_tiocmset_port(struct usb_serial_port *port,
 		unsigned int set, unsigned int clear)
 {
-	unsigned int control = 0;
+	u16 control = 0;
 
 	if (set & TIOCM_RTS) {
 		control |= CONTROL_RTS;
@@ -947,7 +1016,7 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port,
 
 	dev_dbg(&port->dev, "%s - control = 0x%.4x\n", __func__, control);
 
-	return cp210x_set_config(port, CP210X_SET_MHS, &control, 2);
+	return cp210x_write_u16_reg(port, CP210X_SET_MHS, control);
 }
 
 static void cp210x_dtr_rts(struct usb_serial_port *p, int on)
@@ -981,7 +1050,7 @@ static int cp210x_tiocmget(struct tty_struct *tty)
 static void cp210x_break_ctl(struct tty_struct *tty, int break_state)
 {
 	struct usb_serial_port *port = tty->driver_data;
-	unsigned int state;
+	u16 state;
 
 	if (break_state == 0)
 		state = BREAK_OFF;
@@ -989,7 +1058,7 @@ static void cp210x_break_ctl(struct tty_struct *tty, int break_state)
 		state = BREAK_ON;
 	dev_dbg(&port->dev, "%s - turning break %s\n", __func__,
 		state == BREAK_OFF ? "off" : "on");
-	cp210x_set_config(port, CP210X_SET_BREAK, &state, 2);
+	cp210x_write_u16_reg(port, CP210X_SET_BREAK, state);
 }
 
 static int cp210x_port_probe(struct usb_serial_port *port)