linux-kernel - Re: [PATCH] Add poll_get_char and poll_put_char uart_ops to atmel

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Date:	Mon, 27 Jul 2009 16:23:12 +0200
From:	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
To:	Albin Tonnerre <albin.tonnerre@...il.com>
Cc:	avictor.za@...il.com, linux-kernel@...r.kernel.org,
	Albin Tonnerre <albin.tonnerre@...e-electrons.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>
Subject: Re: [PATCH] Add poll_get_char and poll_put_char uart_ops to
 atmel_serial.

[added AT91 maintainers to Cc]

Albin Tonnerre wrote:
> +#ifdef CONFIG_CONSOLE_POLL
> +static int atmel_poll_get_char(struct uart_port *port)
> +{
> +	struct atmel_uart_port *aup = to_atmel_uart_port(port);
> +
> +	while (!(readb(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_RXRDY))
> +		barrier();
> +
> +	return readb(aup->uart.membase + ATMEL_US_RHR);
> +}
> +
> +static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
> +{
> +	struct atmel_uart_port *aup = to_atmel_uart_port(port);
> +	unsigned int status;
> +
> +	while (!(readb(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_TXRDY))
> +		barrier();
> +
> +	writeb(ch, aup->uart.membase + ATMEL_US_THR);
> +}
> +#endif

All the registers are 32 bits wide, so you should use __raw_readl() and
__raw_writel() to avoid any endianness issues (AT91 is little endian
and AVR32 is big endian).

Haavard
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