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>
---
drivers/usb/serial/f81534.c | 74 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 74 insertions(+)
diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 30b966d71ae8..18bd2a478199 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -751,6 +751,74 @@ 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 int 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_register(serial,
+ F81534_MODEM_STATUS_REG + phy * 0x10, &msr);
+ if (status)
+ return status;
+
+ if ((msr & msr_mask) != msr_mask)
+ return 0;
+
+ status = f81534_set_register(serial,
+ F81534_FIFO_CONTROL_REG + phy * 0x10,
+ UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
+ UART_FCR_CLEAR_XMIT);
+ if (status)
+ return status;
+
+ status = f81534_get_register(serial,
+ F81534_MODEM_CONTROL_REG + phy * 0x10,
+ &old_mcr);
+ if (status)
+ return status;
+
+ status = f81534_set_register(serial,
+ F81534_MODEM_CONTROL_REG + phy * 0x10,
+ UART_MCR_LOOP);
+ if (status)
+ return status;
+
+ status = f81534_set_register(serial,
+ F81534_MODEM_CONTROL_REG + phy * 0x10, 0x0);
+ if (status)
+ return status;
+
+ msleep(60);
+
+ status = f81534_get_register(serial,
+ F81534_LINE_STATUS_REG + phy * 0x10, &lsr);
+ if (status)
+ return status;
+
+ status = f81534_set_register(serial,
+ F81534_MODEM_CONTROL_REG + phy * 0x10,
+ old_mcr);
+ if (status)
+ return status;
+
+ if ((lsr & UART_LSR_BI) == UART_LSR_BI)
+ return -ENODEV;
+
+ return 0;
+}
+
+/*
* 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
@@ -832,6 +900,9 @@ 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 (f81534_check_port_hw_disabled(serial, i))
+ continue;
+
if (setting[i] & F81534_PORT_UNAVAILABLE)
continue;
@@ -1306,6 +1377,9 @@ static int f81534_attach(struct usb_serial *serial)
/* Assign phy-to-logic mapping */
for (i = 0; i < F81534_NUM_PORT; ++i) {
+ 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;
--
2.7.4
--
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