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serial: 8250: Add Nuvoton NPCM UART

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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>
This commit is contained in:
Joel Stanley 2018-03-05 22:17:38 +10:30 committed by Greg Kroah-Hartman
parent c0aed3667b
commit cbf733ca58
4 changed files with 38 additions and 0 deletions
Documentation/devicetree/bindings/serial
8250.txt
drivers/tty/serial/8250
8250_of.c8250_port.c
include/uapi/linux
serial_core.h

1
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.

1
drivers/tty/serial/8250/8250_of.c

@ -321,6 +321,7 @@ 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);

33
drivers/tty/serial/8250/8250_port.c

@ -51,6 +51,10 @@
#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.
*/
@ -297,6 +301,15 @@ 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 */
@ -2168,6 +2181,15 @@ 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
@ -2490,6 +2512,15 @@ 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)
@ -2510,6 +2541,8 @@ 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);

3
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