This is a note to let you know that I've just added the patch titled

serial: 8250: Add Nuvoton NPCM UART

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: serial-8250-add-nuvoton-npcm-uart.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From f597fbce38d230af95384f4a04e0a13a1d0ad45d Mon Sep 17 00:00:00 2001

From: Joel Stanley joel@jms.id.au Date: Mon, 5 Mar 2018 22:17:38 +1030 Subject: serial: 8250: Add Nuvoton NPCM UART

From: Joel Stanley joel@jms.id.au

commit f597fbce38d230af95384f4a04e0a13a1d0ad45d upstream.

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.

Reviewed-by: Rob Herring robh@kernel.org Signed-off-by: Joel Stanley joel@jms.id.au Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- Documentation/devicetree/bindings/serial/8250.txt | 1 drivers/tty/serial/8250/8250_of.c | 1 drivers/tty/serial/8250/8250_port.c | 33 ++++++++++++++++++++++ include/uapi/linux/serial_core.h | 3 ++ 4 files changed, 38 insertions(+)

--- 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. --- 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_plat { .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); --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -47,6 +47,10 @@ #define UART_EXAR_SLEEP 0x8b /* Sleep mode */ #define UART_EXAR_DVID 0x8d /* Device identification */

+/* Nuvoton NPCM timeout register */ +#define UART_NPCM_TOR 7 +#define UART_NPCM_TOIE BIT(7) /* Timeout Interrupt Enable */ + /* * Debugging. */ @@ -293,6 +297,15 @@ static const struct serial8250_config ua 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 */ @@ -2161,6 +2174,15 @@ int serial8250_do_startup(struct uart_po 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 @@ -2483,6 +2505,15 @@ static unsigned int xr17v35x_get_divisor 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) @@ -2503,6 +2534,8 @@ static unsigned int serial8250_get_divis 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);

--- 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

Patches currently in stable-queue which might be from joel@jms.id.au are

queue-4.15/serial-8250-add-nuvoton-npcm-uart.patch