* Feng Tang <feng.tang@xxxxxxxxx> wrote:
> Intel Medfield platform has a high speed UART device, which could act
> as a early console. To enable early printk of HSU console, simply add
> "earlyprintk=hsu" in kernel command line.
>
> Currently we put the code in the mrst_earlyprintk.c as it is also for
> Intel MID platforms like the mrst early console
>
> Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> Cc: x86 maintainers <x86@xxxxxxxxxx>
> Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/mrst.h | 1 +
> arch/x86/kernel/early_printk.c | 3 +
> arch/x86/kernel/mrst_earlyprintk.c | 95 +++++++++++++++++++++++++++++++++++-
> 3 files changed, 98 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/mrst.h b/arch/x86/include/asm/mrst.h
> index 4b891b3..37bae64 100644
> --- a/arch/x86/include/asm/mrst.h
> +++ b/arch/x86/include/asm/mrst.h
> @@ -46,4 +46,5 @@ extern enum mrst_timer_options mrst_timer_options;
> #define SFI_MRTC_MAX 8
>
> extern struct console early_mrst_console;
> +extern struct console early_hsu_console;
> #endif /* _ASM_X86_MRST_H */
> diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
> index 435a070..fd095e7 100644
> --- a/arch/x86/kernel/early_printk.c
> +++ b/arch/x86/kernel/early_printk.c
> @@ -243,6 +243,9 @@ static int __init setup_early_printk(char *buf)
> #ifdef CONFIG_X86_MRST_EARLY_PRINTK
> if (!strncmp(buf, "mrst", 4))
> early_console_register(&early_mrst_console, keep);
> +
> + if (!strncmp(buf, "hsu", 3))
> + early_console_register(&early_hsu_console, keep);
> #endif
> buf++;
> }
> diff --git a/arch/x86/kernel/mrst_earlyprintk.c b/arch/x86/kernel/mrst_earlyprintk.c
> index 7c29025..c3f5348 100644
> --- a/arch/x86/kernel/mrst_earlyprintk.c
> +++ b/arch/x86/kernel/mrst_earlyprintk.c
> @@ -1,5 +1,5 @@
> /*
> - * mrst_earlyprintk.c - spi-uart early printk for Intel Moorestown platform
> + * mrst_earlyprintk.c - early consols for Intel MID platforms
s/consols/consoles
> *
> * Copyright (c) 2009 Intel Corporation
> *
> @@ -9,9 +9,19 @@
> * of the License.
> */
>
> +/*
> + * This file implements 2 early consoles named: mrst and hsu.
s/2/two
s/named: mrst/named mrst
> + * mrst is based on Maxim3110 spi-uart device, it exist in both
s/exist/exists
> + * Moorestown and Medfield platforms, while hsu is based on a High
> + * Speed UART device which only exist in Medfield platform
s/exist/exists
s/in Medfield/in the Medfield
> + */
> +
> +#include <linux/serial_reg.h>
> +#include <linux/serial_mfd.h>
> #include <linux/kmsg_dump.h>
> #include <linux/console.h>
> #include <linux/kernel.h>
> +#include <linux/delay.h>
> #include <linux/init.h>
> #include <linux/io.h>
>
> @@ -239,3 +249,86 @@ struct console early_mrst_console = {
> .flags = CON_PRINTBUFFER,
> .index = -1,
> };
> +
> +/*
> + * Following is the early console based on Medfield HSU(High
s/U(/U (
> + * Speed UART) device.
> + */
> +#define HSU_PORT2_PADDR 0xffa28180
> +
> +static int hsu_init_done;
> +static void __iomem *phsu;
> +
> +static void early_hsu_init(void)
> +{
> + u8 lcr;
> +
> + set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, HSU_PORT2_PADDR);
> + phsu = (void *)(__fix_to_virt(FIX_EARLYCON_MEM_BASE) +
> + (HSU_PORT2_PADDR & (PAGE_SIZE - 1)));
I suspect a set_fixmap_nocache_offset() helper would be nice, which
could be used the following simple way:
phsu = set_fixmap_nocache_offset(FIX_EARLYCON_MEM_BASE, HSU_PORT2_PADDR);
Note that such a helper could thus also be used to significantly
simplify the early_mrst_spi_init() function in the mrst driver.
> +
> + writeb(0x0, phsu + UART_FCR);
> +
> + /* Set to default 115200 */
> + lcr = readb(phsu + UART_LCR);
> + writeb((0x80 | lcr), phsu + UART_LCR);
> + writeb(0x18, phsu + UART_DLL);
> + writeb(lcr, phsu + UART_LCR);
> + writel(0x3600, phsu + UART_MUL*4);
> +
> + writeb(0x8, phsu + UART_MCR);
> + writeb(0x7, phsu + UART_FCR);
> + writeb(0x3, phsu + UART_LCR);
> +
> + /* Clear IRQ status */
> + readb(phsu + UART_LSR);
> + readb(phsu + UART_RX);
> + readb(phsu + UART_IIR);
> + readb(phsu + UART_MSR);
> +
> + /* Enable FIFO */
> + writeb(0x7, phsu + UART_FCR);
> +
> + hsu_init_done = 1;
> +}
Same comment as for mrst: please eliminate hsu_init_done and replace it
with properly placed explicit calls to early_hsu_init(). This gives a
much more dependable call graph in the long run.
( You can keep hsu_init_done as a debugging check initially, to make
sure the ->write() method is first called after things have been
initialized. )
> +
> +#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
> +
> +static void early_hsu_putc(char ch)
> +{
> + unsigned int timeout = 10000; /* 10ms */
> + u8 status;
> +
> + while (--timeout) {
> + status = readb(phsu + UART_LSR);
> + if (status & BOTH_EMPTY)
> + break;
> + udelay(1);
> + }
> +
> + /* Only write the char when timeout doesn't happen */
s/when timeout doesn't happen/when there was no timeout
> + if (timeout)
> + writeb(ch, phsu + UART_TX);
> +}
> +
> +static void early_hsu_write(struct console *con, const char *str, unsigned n)
> +{
> + int i;
> +
> + if (unlikely(!hsu_init_done))
> + early_hsu_init();
> +
> + for (i = 0; i < n && *str; i++) {
> + if (*str == '\n')
> + early_hsu_putc('\r');
> + early_hsu_putc(*str);
> + str++;
> + }
> +}
> +
> +struct console early_hsu_console = {
> + .name = "earlyhsu",
> + .write = early_hsu_write,
> + .flags = CON_PRINTBUFFER,
> + .index = -1,
> +};
Thanks,
Ingo
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