[U-Boot] [PATCH 3/7] S3C24XX: Add serial driver

[Marek Vasut]

Dear José Miguel Gonçalves,

> Serial driver for the S3C24XX SoCs.
> 
> Signed-off-by: José Miguel Gonçalves <jose.goncalves at inov.pt>
> ---
>  drivers/serial/Makefile         |    1 +
>  drivers/serial/s3c24xx_serial.c |  146
> +++++++++++++++++++++++++++++++++++++++ 2 files changed, 147 insertions(+)
>  create mode 100644 drivers/serial/s3c24xx_serial.c
> 
> diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> index 65d0f23..2cbdaac 100644
> --- a/drivers/serial/Makefile
> +++ b/drivers/serial/Makefile
> @@ -52,6 +52,7 @@ COBJS-$(CONFIG_PL011_SERIAL) += serial_pl01x.o
>  COBJS-$(CONFIG_PXA_SERIAL) += serial_pxa.o
>  COBJS-$(CONFIG_SA1100_SERIAL) += serial_sa1100.o
>  COBJS-$(CONFIG_S3C24X0_SERIAL) += serial_s3c24x0.o
> +COBJS-$(CONFIG_S3C24XX_SERIAL) += s3c24xx_serial.o

What's the difference between those two drivers ?!

>  COBJS-$(CONFIG_S3C44B0_SERIAL) += serial_s3c44b0.o
>  COBJS-$(CONFIG_XILINX_UARTLITE) += serial_xuartlite.o
>  COBJS-$(CONFIG_SANDBOX_SERIAL) += sandbox.o
> diff --git a/drivers/serial/s3c24xx_serial.c
> b/drivers/serial/s3c24xx_serial.c new file mode 100644
> index 0000000..11f13a5
> --- /dev/null
> +++ b/drivers/serial/s3c24xx_serial.c
> @@ -0,0 +1,146 @@
> +/*
> + * (C) Copyright 2012 INOV - INESC Inovacao
> + * Jose Goncalves <jose.goncalves at inov.pt>
> + *
> + * Based on drivers/serial/s3c64xx.c
> + *
> + * See file CREDITS for list of people who contributed to this
> + * project.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + */
> +
> +#include <common.h>
> +#include <asm/arch/s3c24xx_cpu.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +#ifdef CONFIG_SERIAL0
> +#define UART_NR	S3C24XX_UART0
> +
> +#elif defined(CONFIG_SERIAL1)
> +#define UART_NR	S3C24XX_UART1
> +
> +#elif defined(CONFIG_SERIAL2)
> +#define UART_NR	S3C24XX_UART2
> +
> +#elif defined(CONFIG_SERIAL3)
> +#define UART_NR	S3C24XX_UART3
> +
> +#else
> +#error "Bad: you didn't configure serial ..."

Error itself is "Bad:" so remove it

> +#endif
> +
> +#define barrier() asm volatile("" ::: "memory")

Is that even used ?

> +/*
> + * The coefficient, used to calculate the baudrate on S3C24XX UARTs is
> + * calculated as C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
> + * however, section 2.1.10 of the S3C2416 User's Manual doesn't recommend
> + * using 1 for 1, 3 for 2, ... (2^n - 1) for n, instead, they suggest
> using + * these constants:
> + */
> +static const int udivslot[] = {

const int const ... const array const members

> +	0x0000, 0x0080, 0x0808, 0x0888, 0x2222, 0x4924, 0x4A52, 0x54AA,
> +	0x5555, 0xD555, 0xD5D5, 0xDDD5, 0xDDDD, 0xDFDD, 0xDFDF, 0xFFDF,
> +};
> +
> +void serial_setbrg(void)
> +{
> +	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
> +	u32 pclk;
> +	u32 baudrate;
> +	int i;
> +
> +	pclk = get_PCLK();
> +	baudrate = gd->baudrate;
> +
> +	uart->ubrdiv = (pclk / baudrate / 16) - 1;
> +	uart->udivslot = udivslot[(pclk / baudrate) % 16];
> +
> +	for (i = 0; i < 100; i++)
> +		barrier();
> +}
> +
> +/*
> + * Initialise the serial port with the given baudrate. The settings
> + * are always 8 data bits, no parity, 1 stop bit, no start bits.
> + */
> +int serial_init(void)
> +{
> +	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
> +
> +	/* FIFO enable, Tx/Rx FIFO clear */
> +	uart->ufcon = 0x07;
> +	uart->umcon = 0x00;

Magic numbers, fix

> +	/* Normal mode, No parity, 1 stop bit, 8 data bits */
> +	uart->ulcon = 0x03;
> +	/* Polling mode */
> +	uart->ucon = 0x005;
> +
> +	serial_setbrg();
> +
> +	return 0;
> +}
> +
> +/*
> + * Read a single byte from the serial port.
> + */
> +int serial_getc(void)
> +{
> +	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
> +
> +	/* Wait for character to arrive */
> +	while (!(uart->utrstat & 0x1)) ;
> +
> +	return uart->urxh & 0xff;
> +}
> +
> +/*
> + * Output a single byte to the serial port.
> + */
> +void serial_putc(const char c)
> +{
> +	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
> +
> +	/* Wait for room in the TX FIFO */
> +	while (!(uart->utrstat & 0x2)) ;
> +
> +	uart->utxh = c;
> +
> +	/* If \n, also do \r */
> +	if (c == '\n')
> +		serial_putc('\r');
> +}
> +
> +/*
> + * Test whether a character is in the RX buffer.
> + */
> +int serial_tstc(void)
> +{
> +	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
> +
> +	return uart->utrstat & 0x1;
> +}
> +
> +/*
> + * Output a string to the serial port.
> + */
> +void serial_puts(const char *s)
> +{
> +	while (*s)
> +		serial_putc(*s++);
> +}

Can you implement it as a serial multi (CONFIG_SERIAL_MULTI) right away ? 
thanks.

Best regards,
Marek Vasut