On 10/22/2015 07:36 PM, Timur Tabi wrote:
> On Fri, Sep 18, 2015 at 5:51 AM, Andre Przywara <andre.przywara@xxxxxxx> wrote:
>>
>>> static void pl011_putc(struct uart_port *port, int c)
>>> {
>>> - while (readl(port->membase + REG_FR) & UART01x_FR_TXFF)
>>> + struct uart_amba_port *uap =
>>> + container_of(port, struct uart_amba_port, port);
>>> +
>>> + while (pl011_readw(uap, REG_FR) & UART01x_FR_TXFF)
>>> ;
>>> - writeb(c, port->membase + REG_DR);
>>> - while (readl(port->membase + REG_FR) & UART01x_FR_BUSY)
>>> + pl011_writeb(uap, c, REG_DR);
>>> + while (pl011_readw(uap, REG_FR) & UART01x_FR_BUSY)
>>> ;
>>> }
>>
>> Just for the records, as this has been discussed before: pl011_putc() is
>> called by the earlycon code, before the uart_port is actually
>> initialized. So we cannot rely on the accessors, but have to use the
>> old-fashioned director accessors for this.
>>
>> Which means you cannot use that approach to get earlycon support for the
>> ZTE UART, if I get this correctly. It shouldn't be to hard to introduce
>> another earlycon type specificly for that one, copying pl011_early_write
>> and pl011_early_console_setup and changing pl011_putc into
>> zte_uart_putc. But of course this belongs into the final patch (or a
>> separate one), not in this. So I guess you just leave that function
>> unchanged in this patch.
>
> How about something like this? It adds the "sbsa32" option to the
> earlycon command-line parameter.
>
> static void pl011_putc(struct uart_port *port, int c)
> {
> while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> cpu_relax();
> writeb(c, port->membase + UART01x_DR);
> while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> cpu_relax();
> }
>
> static void pl011_early_write(struct console *con, const char *s, unsigned n)
> {
> struct earlycon_device *dev = con->data;
>
> uart_console_write(&dev->port, s, n, pl011_putc);
> }
>
> static void pl011_putc_sbsa32(struct uart_port *port, int c)
> {
> while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> cpu_relax();
> writel(c, port->membase + UART01x_DR);
> while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> cpu_relax();
> }
>
> static void pl011_early_write_sbsa32(struct console *con, const char
> *s, unsigned n)
> {
> struct earlycon_device *dev = con->data;
>
> uart_console_write(&dev->port, s, n, pl011_putc_sbsa32);
> }
>
> static int __init pl011_early_console_setup(struct earlycon_device *device,
> const char *opt)
> {
> if (!device->port.membase)
> return -ENODEV;
>
> if (strcmp(device->options, "sbsa32"))
> device->con->write = pl011_early_write_sbsa32;
> else
> device->con->write = pl011_early_write;
>
> return 0;
> }
For earlycon support, I'd prefer to see different OF_EARLYCON_DECLARE()
(and EARLYCON_DECLARE()) declarations with alternate setup() functions
for zte and sbsa32. For example:
static int __init zte_early_console_setup(struct earlycon_device *device,
const char *opt)
{
if (!device->port.membase)
return -ENODEV;
device->con->write = zte_early_write;
return 0;
}
static int __init sbsa32_early_console_setup(struct earlycon_device *device,
const char *opt)
{
if (!device->port.membase)
return -ENODEV;
device->con->write = sbsa32_early_write;
return 0;
}
EARLYCON_DECLARE(zte, zte_early_console_setup);
OF_EARLYCON_DECLARE(zte, ".......", zte_early_console_setup);
EARLYCON_DECLARE(sbsa32, sbsa32_early_console_setup);
OF_EARLYCON_DECLARE(sbsa32, "arm,sbsa-uart", sbsa32_early_console_setup);
The above assumes that the sbsa32 maintains the equivalence of
earlycon and console; ie., that
/ {
chosen {
stdout-path = &uart0;
};
soc {
uart0: serial@xxxxxx {
compatible = "arm,sbsa-uart";
};
};
};
will start a sbsa32 earlycon and later replace that with
sbsa console.
Regards,
Peter Hurley
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