USB: serial: f81534: fix reading old/new IC config

The F81532/534 had a internal configuration space to save & control
IC state with address F81534_CUSTOM_ADDRESS_START (0x2f00). Layout
as following:
+00h: to indicate the section is valid
+01h~04h: UART Mode & port availability
+05h~08h: Output pin control on IC power on
+09h~12h: Output pin control on working <-- New added

Old driver will use +05~08h as default on working, but newer IC will
configed with shutdown mode(7) in 05h~08h and working mode with RS232(1)
in 09h~12h. It'll make mainstream driver not working.

This patch will make mainstream driver compatible older and newer IC.
If using a old IC, the +05h~08h will be 00h~06h, we'll direct apply it.
If using a new IC, the +05h~08h will be 07h or larger, we'll read +09h~12h
to apply newer configuration.

Signed-off-by: Ji-Ze Hong (Peter Hong) <[e-mail]>
Signed-off-by: Johan Hovold <[e-mail]>

drivers/usb/serial/f81534.c

···
 #define F81534_CONFIG1_REG		(0x09 + F81534_UART_BASE_ADDRESS)
 
 #define F81534_DEF_CONF_ADDRESS_START	0x3000
-#define F81534_DEF_CONF_SIZE		8
+#define F81534_DEF_CONF_SIZE		12
 
 #define F81534_CUSTOM_ADDRESS_START	0x2f00
 #define F81534_CUSTOM_DATA_SIZE		0x10
 #define F81534_CUSTOM_NO_CUSTOM_DATA	0xff
 #define F81534_CUSTOM_VALID_TOKEN	0xf0
 #define F81534_CONF_OFFSET		1
-#define F81534_CONF_GPIO_OFFSET		4
+#define F81534_CONF_INIT_GPIO_OFFSET	4
+#define F81534_CONF_WORK_GPIO_OFFSET	8
+#define F81534_CONF_GPIO_SHUTDOWN	7
+#define F81534_CONF_GPIO_RS232		1
 
 #define F81534_MAX_DATA_BLOCK		64
 #define F81534_MAX_BUS_RETRY		20
···
 	serial_priv = usb_get_serial_data(serial);
 	port_priv = usb_get_serial_port_data(port);
 
-	idx = F81534_CONF_GPIO_OFFSET + port_priv->phy_num;
+	idx = F81534_CONF_INIT_GPIO_OFFSET + port_priv->phy_num;
 	value = serial_priv->conf_data[idx];
+	if (value >= F81534_CONF_GPIO_SHUTDOWN) {
+		/*
+		 * Newer IC configure will make transceiver in shutdown mode on
+		 * initial power on. We need enable it before using UARTs.
+		 */
+		idx = F81534_CONF_WORK_GPIO_OFFSET + port_priv->phy_num;
+		value = serial_priv->conf_data[idx];
+		if (value >= F81534_CONF_GPIO_SHUTDOWN)
+			value = F81534_CONF_GPIO_RS232;
+	}
+
 	pins = &f81534_port_out_pins[port_priv->phy_num];
 
 	for (i = 0; i < ARRAY_SIZE(pins->pin); ++i) {