[PATCH V2 4/5] usb: serial: f81534: add H/W disable port support

[Ji-Ze Hong (Peter Hong)]

The F81532/534 can be disable port by manufacturer with
following H/W design.
    1: Connect DCD/DSR/CTS/RI pin to ground.
    2: Connect RX pin to ground.

In driver, we'll implements some detect method likes following:
    1: Read MSR.
    2: Turn MCR LOOP bit on, off and read LSR after delay with 60ms.
       It'll contain BREAK status in LSR.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@xxxxxxxxx>
---
V2:
	1: f81534_check_port_hw_disabled() change return type from int to bool.
	2: Add help function f81534_set_phy_port_register() /
	   f81534_get_phy_port_register() for f81534_check_port_hw_disabled()
	   to read register without port.
	3: Re-write f81534_calc_num_ports() & f81534_attach() to reduce the
	   f81534_check_port_hw_disabled() repeatedly called.

 drivers/usb/serial/f81534.c | 160 +++++++++++++++++++++++++++-----------------
 1 file changed, 99 insertions(+), 61 deletions(-)

diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 7f175f39a171..a4666171239a 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -307,6 +307,20 @@ static int f81534_set_mask_register(struct usb_serial *serial, u16 reg,
 	return f81534_set_register(serial, reg, tmp);
 }
 
+static int f81534_set_phy_port_register(struct usb_serial *serial, int phy,
+					u16 reg, u8 data)
+{
+	return f81534_set_register(serial, reg + F81534_UART_OFFSET * phy,
+					data);
+}
+
+static int f81534_get_phy_port_register(struct usb_serial *serial, int phy,
+					u16 reg, u8 *data)
+{
+	return f81534_get_register(serial, reg + F81534_UART_OFFSET * phy,
+					data);
+}
+
 static int f81534_set_port_register(struct usb_serial_port *port, u16 reg,
 					u8 data)
 {
@@ -730,6 +744,70 @@ static int f81534_find_config_idx(struct usb_serial *serial, u8 *index)
 }
 
 /*
+ * The F81532/534 will not report serial port to USB serial subsystem when
+ * H/W DCD/DSR/CTS/RI/RX pin connected to ground.
+ *
+ * To detect RX pin status, we'll enable MCR interal loopback, disable it and
+ * delayed for 60ms. It connected to ground If LSR register report UART_LSR_BI.
+ */
+static bool f81534_check_port_hw_disabled(struct usb_serial *serial, int phy)
+{
+	int status;
+	u8 old_mcr;
+	u8 msr;
+	u8 lsr;
+	u8 msr_mask;
+
+	msr_mask = UART_MSR_DCD | UART_MSR_RI | UART_MSR_DSR | UART_MSR_CTS;
+
+	status = f81534_get_phy_port_register(serial, phy,
+				F81534_MODEM_STATUS_REG, &msr);
+	if (status)
+		return false;
+
+	if ((msr & msr_mask) != msr_mask)
+		return false;
+
+	status = f81534_set_phy_port_register(serial, phy,
+				F81534_FIFO_CONTROL_REG, UART_FCR_ENABLE_FIFO |
+				UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
+	if (status)
+		return false;
+
+	status = f81534_get_phy_port_register(serial, phy,
+				F81534_MODEM_CONTROL_REG, &old_mcr);
+	if (status)
+		return false;
+
+	status = f81534_set_phy_port_register(serial, phy,
+				F81534_MODEM_CONTROL_REG, UART_MCR_LOOP);
+	if (status)
+		return false;
+
+	status = f81534_set_phy_port_register(serial, phy,
+				F81534_MODEM_CONTROL_REG, 0x0);
+	if (status)
+		return false;
+
+	msleep(60);
+
+	status = f81534_get_phy_port_register(serial, phy,
+				F81534_LINE_STATUS_REG, &lsr);
+	if (status)
+		return false;
+
+	status = f81534_set_phy_port_register(serial, phy,
+				F81534_MODEM_CONTROL_REG, old_mcr);
+	if (status)
+		return false;
+
+	if ((lsr & UART_LSR_BI) == UART_LSR_BI)
+		return true;
+
+	return false;
+}
+
+/*
  * We had 2 generation of F81532/534 IC. All has an internal storage.
  *
  * 1st is pure USB-to-TTL RS232 IC and designed for 4 ports only, no any
@@ -750,11 +828,10 @@ static int f81534_find_config_idx(struct usb_serial *serial, u8 *index)
 static int f81534_calc_num_ports(struct usb_serial *serial,
 					struct usb_serial_endpoints *epds)
 {
+	struct f81534_serial_private *serial_priv;
 	struct device *dev = &serial->interface->dev;
 	int size_bulk_in = usb_endpoint_maxp(epds->bulk_in[0]);
 	int size_bulk_out = usb_endpoint_maxp(epds->bulk_out[0]);
-	u8 setting[F81534_CUSTOM_DATA_SIZE];
-	u8 setting_idx;
 	u8 num_port = 0;
 	int status;
 	size_t i;
@@ -765,8 +842,15 @@ static int f81534_calc_num_ports(struct usb_serial *serial,
 		return -ENODEV;
 	}
 
+	serial_priv = devm_kzalloc(&serial->interface->dev,
+					sizeof(*serial_priv), GFP_KERNEL);
+	if (!serial_priv)
+		return -ENOMEM;
+
+	usb_set_serial_data(serial, serial_priv);
+
 	/* Check had custom setting */
-	status = f81534_find_config_idx(serial, &setting_idx);
+	status = f81534_find_config_idx(serial, &serial_priv->setting_idx);
 	if (status) {
 		dev_err(&serial->interface->dev, "%s: find idx failed: %d\n",
 				__func__, status);
@@ -777,11 +861,12 @@ static int f81534_calc_num_ports(struct usb_serial *serial,
 	 * We'll read custom data only when data available, otherwise we'll
 	 * read default value instead.
 	 */
-	if (setting_idx != F81534_CUSTOM_NO_CUSTOM_DATA) {
+	if (serial_priv->setting_idx != F81534_CUSTOM_NO_CUSTOM_DATA) {
 		status = f81534_read_flash(serial,
 						F81534_CUSTOM_ADDRESS_START +
 						F81534_CONF_OFFSET,
-						sizeof(setting), setting);
+						sizeof(serial_priv->conf_data),
+						serial_priv->conf_data);
 		if (status) {
 			dev_err(&serial->interface->dev,
 					"%s: get custom data failed: %d\n",
@@ -791,13 +876,13 @@ static int f81534_calc_num_ports(struct usb_serial *serial,
 
 		dev_dbg(&serial->interface->dev,
 				"%s: read config from block: %d\n", __func__,
-				setting_idx);
+				serial_priv->setting_idx);
 	} else {
 		/* Read default board setting */
 		status = f81534_read_flash(serial,
-				F81534_DEF_CONF_ADDRESS_START, F81534_NUM_PORT,
-				setting);
-
+				F81534_DEF_CONF_ADDRESS_START,
+				sizeof(serial_priv->conf_data),
+				serial_priv->conf_data);
 		if (status) {
 			dev_err(&serial->interface->dev,
 					"%s: read failed: %d\n", __func__,
@@ -811,7 +896,10 @@ static int f81534_calc_num_ports(struct usb_serial *serial,
 
 	/* New style, find all possible ports */
 	for (i = 0; i < F81534_NUM_PORT; ++i) {
-		if (setting[i] & F81534_PORT_UNAVAILABLE)
+		if (f81534_check_port_hw_disabled(serial, i))
+			serial_priv->conf_data[i] |= F81534_PORT_UNAVAILABLE;
+
+		if (serial_priv->conf_data[i] & F81534_PORT_UNAVAILABLE)
 			continue;
 
 		++num_port;
@@ -1228,61 +1316,11 @@ static int f81534_attach(struct usb_serial *serial)
 {
 	struct f81534_serial_private *serial_priv;
 	int index = 0;
-	int status;
 	int i;
 
-	serial_priv = devm_kzalloc(&serial->interface->dev,
-					sizeof(*serial_priv), GFP_KERNEL);
-	if (!serial_priv)
-		return -ENOMEM;
-
-	usb_set_serial_data(serial, serial_priv);
-
+	serial_priv = usb_get_serial_data(serial);
 	mutex_init(&serial_priv->urb_mutex);
 
-	/* Check had custom setting */
-	status = f81534_find_config_idx(serial, &serial_priv->setting_idx);
-	if (status) {
-		dev_err(&serial->interface->dev, "%s: find idx failed: %d\n",
-				__func__, status);
-		return status;
-	}
-
-	/*
-	 * We'll read custom data only when data available, otherwise we'll
-	 * read default value instead.
-	 */
-	if (serial_priv->setting_idx == F81534_CUSTOM_NO_CUSTOM_DATA) {
-		/*
-		 * The default configuration layout:
-		 *	byte 0/1/2/3: uart setting
-		 */
-		status = f81534_read_flash(serial,
-					F81534_DEF_CONF_ADDRESS_START,
-					F81534_DEF_CONF_SIZE,
-					serial_priv->conf_data);
-		if (status) {
-			dev_err(&serial->interface->dev,
-					"%s: read reserve data failed: %d\n",
-					__func__, status);
-			return status;
-		}
-	} else {
-		/* Only read 8 bytes for mode & GPIO */
-		status = f81534_read_flash(serial,
-						F81534_CUSTOM_ADDRESS_START +
-						F81534_CONF_OFFSET,
-						sizeof(serial_priv->conf_data),
-						serial_priv->conf_data);
-		if (status) {
-			dev_err(&serial->interface->dev,
-					"%s: idx: %d get data failed: %d\n",
-					__func__, serial_priv->setting_idx,
-					status);
-			return status;
-		}
-	}
-
 	/* Assign phy-to-logic mapping */
 	for (i = 0; i < F81534_NUM_PORT; ++i) {
 		if (serial_priv->conf_data[i] & F81534_PORT_UNAVAILABLE)
-- 
2.7.4