On 1 March 2013 13:47, Marc Zyngier <marc.zyng...@arm.com> wrote:
>
> On Fri, 1 Mar 2013 11:30:26 +0530, Anup Patel <anup.pa...@linaro.org>
> wrote:
> > This patch adds support for using earlyprintk with 8250/16550 UART
> ports.
> >
> > The 8250/16550 UART can either have 8-bit or 32-bit aligned registers
> > which is HW vendor dependent.
> >
> > Kernel args for 8-bit aligned regs:
> > earlyprintk=uart8250-8bit,<phys_address>
> >
> > Kernel args for 32-bit aligned regs:
> > earlyprintk=uart8250-16bit,<phys_address>
> ^^^^^
>
> Please fix this comment to match the actual code.
Sure, I will fix this.
>
>
> > Signed-off-by: Anup Patel <anup.pa...@linaro.org>
> > ---
> > arch/arm64/kernel/early_printk.c | 23 +++++++++++++++++++++++
> > 1 file changed, 23 insertions(+)
> >
> > diff --git a/arch/arm64/kernel/early_printk.c
> > b/arch/arm64/kernel/early_printk.c
> > index 7e320a2..d57f300 100644
> > --- a/arch/arm64/kernel/early_printk.c
> > +++ b/arch/arm64/kernel/early_printk.c
> > @@ -24,11 +24,32 @@
> > #include <linux/io.h>
> >
> > #include <linux/amba/serial.h>
> > +#include <uapi/linux/serial_reg.h>
>
> You do not need to refer to uapi here. <linux/serial_reg.h> should be
> enough.
Ok, I will use <linux/serial_reg.h>
>
>
> > static void __iomem *early_base;
> > static void (*printch)(char ch);
> >
> > /*
> > + * 8250/16550 (8-bit aligned registers) single character TX.
> > + */
> > +static void uart8250_8bit_printch(char ch)
> > +{
> > + while (!(readb_relaxed(early_base + UART_LSR) & UART_LSR_THRE))
> > + ;
> > + writeb_relaxed(ch, early_base + UART_TX);
> > +}
> > +
> > +/*
> > + * 8250/16550 (32-bit aligned registers) single character TX.
> > + */
> > +static void uart8250_32bit_printch(char ch)
> > +{
> > + while (!(readl_relaxed(early_base + (UART_LSR << 2)) & UART_LSR_THRE))
> > + ;
> > + writel_relaxed(ch, early_base + (UART_TX << 2));
> > +}
> > +
> > +/*
> > * PL011 single character TX.
> > */
> > static void pl011_printch(char ch)
> > @@ -47,6 +68,8 @@ struct earlycon_match {
> >
> > static const struct earlycon_match earlycon_match[] __initconst = {
> > { .name = "pl011", .printch = pl011_printch, },
> > + { .name = "uart8250-8bit", .printch = uart8250_8bit_printch, },
> > + { .name = "uart8250-32bit", .printch = uart8250_32bit_printch, },
> > {}
> > };
>
> --
> Fast, cheap, reliable. Pick two.
Regards,
Anup
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