[PATCH v2 5/5] tty/serial: Add earlycon support for Spreadtrum serial driver

One Thousand Gnomes
2014-10-18T21:06:15Z

On Fri, 17 Oct 2014 17:54:25 +0800
Chunyan Zhang <chunyan.zhang@spreadtrum.com> wrote:

> Add serial driver for spreadtrum sharkl platform with earlycon
> support at first.

> +#define UART_TXD 0x0000
> +#define UART_RXD 0x0004
> +#define UART_STS0 0x0008
> +#define UART_STS1 0x000C
> +#define UART_IEN 0x0010
> +#define UART_ICLR 0x0014
> +#define UART_CTL0 0x0018
> +#define UART_CTL1 0x001C
> +#define UART_CTL2 0x0020
> +#define UART_CLKD0 0x0024
> +#define UART_CLKD1 0x0028
> +#define UART_STS2 0x002C
> +
> +/*line status */
> +#define UART_LSR_TX_OVER (0x1<<15)

Given we use UART_ for all the 8250 defines it might be better to use
something else - SHARK_LSR_TX_OVER etc to avoid future confusion

> +static void serial_sprd_putc(struct uart_port *port, int c)
> +{
> + while (!(readl(port->membase + UART_STS0) & UART_LSR_TX_OVER))
> + ;
> + writeb(c, port->membase + UART_TXD);
> +}
> +
> +static void serial_sprd_early_write(struct console *con, const char *s,
> + unsigned n)
> +{
> + struct earlycon_device *dev = con->data;
> +
> + uart_console_write(&dev->port, s, n, serial_sprd_putc);
> +}
> +
> +static int __init serial_sprd_early_console_setup(
> + struct earlycon_device *device,
> + const char *opt)
> +{
> + if (!device->port.membase)
> + return -ENODEV;
> +
> + device->con->write = serial_sprd_early_write;
> + return 0;
> +}

This seems fine but it would be useful to see both the earlycon and the
main uart/console driver and how they fit together.

Alan