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_ker...@gmail.com>
---
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

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