The Nuvoton UART is almost compatible with the 8250 driver when probed
via the 8250_of driver, however it requires some extra configuration
at startup.
Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
---
v2:
Remove redundant whitespace
Use port number 40 to fill in a gap
Documentation/devicetree/bindings/serial/8250.txt | 1 +
drivers/tty/serial/8250/8250_of.c | 1 +
drivers/tty/serial/8250/8250_port.c | 29 +++++++++++++++++++++++
include/uapi/linux/serial_core.h | 3 +++
include/uapi/linux/serial_reg.h | 5 ++++
5 files changed, 39 insertions(+)
diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt
index dad3b2ec66d4..aeb6db4e35c3 100644
--- a/Documentation/devicetree/bindings/serial/8250.txt
+++ b/Documentation/devicetree/bindings/serial/8250.txt
@@ -24,6 +24,7 @@ Required properties:
- "ti,da830-uart"
- "aspeed,ast2400-vuart"
- "aspeed,ast2500-vuart"
+ - "nuvoton,npcm750-uart"
- "serial" if the port type is unknown.
- reg : offset and length of the register set for the device.
- interrupts : should contain uart interrupt.
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 160b8906d9b9..9835b1c1cbe1 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -316,6 +316,7 @@ static const struct of_device_id of_platform_serial_table[] = {
{ .compatible = "mrvl,mmp-uart",
.data = (void *)PORT_XSCALE, },
{ .compatible = "ti,da830-uart", .data = (void *)PORT_DA830, },
+ { .compatible = "nuvoton,npcm750-uart", .data = (void *)PORT_NPCM, },
{ /* end of list */ },
};
MODULE_DEVICE_TABLE(of, of_platform_serial_table);
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 1328c7e70108..a72222f8b005 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -293,6 +293,15 @@ static const struct serial8250_config uart_config[] = {
UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
.flags = UART_CAP_FIFO,
},
+ [PORT_NPCM] = {
+ .name = "Nuvoton 16550",
+ .fifo_size = 16,
+ .tx_loadsz = 16,
+ .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
+ UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
+ .rxtrig_bytes = {1, 4, 8, 14},
+ .flags = UART_CAP_FIFO,
+ },
};
/* Uart divisor latch read */
@@ -2140,6 +2149,15 @@ int serial8250_do_startup(struct uart_port *port)
UART_DA830_PWREMU_MGMT_FREE);
}
+ if (port->type == PORT_NPCM) {
+ /*
+ * Nuvoton calls the scratch register 'UART_TOR' (timeout
+ * register). Enable it, and set TIOC (timeout interrupt
+ * comparator) to be 0x20 for correct operation.
+ */
+ serial_port_out(port, UART_NPCM_TOR, UART_NPCM_TOIE | 0x20);
+ }
+
#ifdef CONFIG_SERIAL_8250_RSA
/*
* If this is an RSA port, see if we can kick it up to the
@@ -2462,6 +2480,15 @@ static unsigned int xr17v35x_get_divisor(struct uart_8250_port *up,
return quot_16 >> 4;
}
+/* Nuvoton NPCM UARTs have a custom divisor calculation */
+static unsigned int npcm_get_divisor(struct uart_8250_port *up,
+ unsigned int baud)
+{
+ struct uart_port *port = &up->port;
+
+ return DIV_ROUND_CLOSEST(port->uartclk, 16 * baud + 2) - 2;
+}
+
static unsigned int serial8250_get_divisor(struct uart_8250_port *up,
unsigned int baud,
unsigned int *frac)
@@ -2482,6 +2509,8 @@ static unsigned int serial8250_get_divisor(struct uart_8250_port *up,
quot = 0x8002;
else if (up->port.type == PORT_XR17V35X)
quot = xr17v35x_get_divisor(up, baud, frac);
+ else if (up->port.type == PORT_NPCM)
+ quot = npcm_get_divisor(up, baud);
else
quot = uart_get_divisor(port, baud);
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 1c8413f93e3d..dce5f9dae121 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -76,6 +76,9 @@
#define PORT_SUNZILOG 38
#define PORT_SUNSAB 39
+/* Nuvoton UART */
+#define PORT_NPCM 40
+
/* Intel EG20 */
#define PORT_PCH_8LINE 44
#define PORT_PCH_2LINE 45
diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
index be07b5470f4b..f82f3c869df9 100644
--- a/include/uapi/linux/serial_reg.h
+++ b/include/uapi/linux/serial_reg.h
@@ -376,5 +376,10 @@
#define UART_ALTR_EN_TXFIFO_LW 0x01 /* Enable the TX FIFO Low Watermark */
#define UART_ALTR_TX_LOW 0x41 /* Tx FIFO Low Watermark */
+
+/* Nuvoton NPCM timeout register */
+#define UART_NPCM_TOR 7
+#define UART_NPCM_TOIE BIT(7) /* Timeout Interrupt Enable */
+
#endif /* _LINUX_SERIAL_REG_H */
--
2.15.1
--
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