| Message ID | 1362127307-7986-1-git-send-email-anup.patel@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 1 Mar 2013 14:11:47 +0530, Anup Patel <anup.patel@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=uart8250-32bit,<phys_address> > > Signed-off-by: Anup Patel <anup.patel@linaro.org> Looks OK to me. FWIW: Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
On Fri, Mar 01, 2013 at 08:41:47AM +0000, Anup Patel 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=uart8250-32bit,<phys_address> > > Signed-off-by: Anup Patel <anup.patel@linaro.org> Thanks. I'll queue it for 3.10.
diff --git a/arch/arm64/kernel/early_printk.c b/arch/arm64/kernel/early_printk.c index 7e320a2..c39e90b 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 <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, }, {} };
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=uart8250-32bit,<phys_address> Signed-off-by: Anup Patel <anup.patel@linaro.org> --- arch/arm64/kernel/early_printk.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)