* Alan Cox <alan@xxxxxxxxxxxxxxx> wrote:
> From: Feng Tang <feng.tang@xxxxxxxxx>
>
> To enable early printk of HSU console, simply set "earlyprint=hsu" in
> kernel command line.
>
> Currently we put the code in the mrst_earlyprintk.c and it need enable
> CONFIG_X86_MRST_EARLY_PRINTK config option
>
> Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> 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 | 128 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 132 insertions(+), 0 deletions(-)
Please Cc: x86 patches to the x86 maintainers.
> diff --git a/arch/x86/include/asm/mrst.h b/arch/x86/include/asm/mrst.h
> index 704d2fd..b6531da 100644
> --- a/arch/x86/include/asm/mrst.h
> +++ b/arch/x86/include/asm/mrst.h
> @@ -46,5 +46,6 @@ 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;
> extern void mrst_early_printk(const char *fmt, ...);
> #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 4aff765..1fb1305 100644
> --- a/arch/x86/kernel/mrst_earlyprintk.c
> +++ b/arch/x86/kernel/mrst_earlyprintk.c
> @@ -9,9 +9,12 @@
> * of the License.
> */
>
> +#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>
>
> @@ -281,3 +284,128 @@ void mrst_early_printk(const char *fmt, ...)
>
> early_mrst_console.write(&early_mrst_console, buf, n);
> }
> +
> +
> +/* Will use HSU port2 for early console */
> +
> +/*
> + * Note:
> + * 1. still need GPIO workaround for UART2
> + *
> + */
> +static spinlock_t hsu_lock;
Please use DEFINE_SPINLOCK().
> +static int hsu_inited;
'initialized' is the proper English word i think.
> +static void __iomem *phsu;
> +#define HSU_PORT2_PADDR 0xffa28180
Newline undersupply.
(Please use newlines to separate blocks of different types of
definitions.)
> +#define MFD_GPIO_HSU_REG 0xff12c064
> +
> +static void early_hsu_init(void)
> +{
> + u8 lcr;
> +
> + if (phsu && hsu_inited)
> + return;
Surely one of those will suffice as a "have we initialized" flag?
Also, under what circumstances can we call early_hsu_init() twice?
> +
> + spin_lock_init(&hsu_lock);
Can be removed if it's DEFINE_SPINLOCK() declared.
> +
> + /* GPIO workaround */
> + set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, MFD_GPIO_HSU_REG);
> + phsu = (void *)(__fix_to_virt(FIX_EARLYCON_MEM_BASE) +
> + (MFD_GPIO_HSU_REG & (PAGE_SIZE - 1)));
> +
> + *((u32 *)phsu) = 0x55465;
What does 0x55465 stand for?
> +
> + 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)));
> +
> + 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);
> +
> +
> +
Newline oversupply.
> + writeb(0x7, phsu + UART_FCR);
> +
> + hsu_inited = 1;
> +}
> +
> +#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
> +static void early_hsu_putc(char ch)
Newline undersupply.
> +{
> + unsigned int timeout = 10000; /* 10ms*/
> + u8 status;
> +
> + while (timeout--) {
> + status = readb(phsu + UART_LSR);
> + if (status & BOTH_EMPTY)
> + break;
> +
> + udelay(1);
> + }
> +
> + if (timeout == 0xffffffff)
> + return;
Using the -1 literal will dtrt too, and will be slightly clearer to the
potentially overworked reader of such patches.
> +
> + writeb(ch, phsu + UART_TX);
> +}
> +
> +static void early_hsu_write(struct console *con,
> + const char *str, unsigned n)
Unnecessary linebreak. Ignore checkpatch when it suggests crap.
> +{
> + int i;
Space character oversupply.
> + unsigned long flags;
> +
> + /*
> + printk("%s(): enter\n\n", __func__);
> + */
Can go away i suspect.
> +
> + if (unlikely(!hsu_inited))
> + early_hsu_init();
We check the 'hsu_inited' flag in early_hsu_init() too. One of the
checks is superfluous.
> +
> + spin_lock_irqsave(&hsu_lock, flags);
In early_printk code we generally try to avoid the use of spinlocks.
It is a 'console of last resort', and we try to keep it as simple as
possible. The current early_printk.c code does not have a single
spinlock, and still it's robust and usable in a wide range of
circumstances, is NMI safe, etc.
With allowing early_hsu_putc() to execute in parallel, we at most can
lose a character, because the UART's BOTH_EMPTY state might be stale.
But it's not a real issue in practice: default earlyprintk is turned off
way before SMP initializes.
> + for (i = 0; i < n && *str; i++) {
> + if (*str == '\n')
> + early_hsu_putc('\r');
> + early_hsu_putc(*str);
> +
> + str++;
> + }
> + spin_unlock_irqrestore(&hsu_lock, flags);
> +}
> +
> +
> +struct console early_hsu_console = {
> + .name = "earlyhsu",
> + .write = early_hsu_write,
> + .flags = CON_PRINTBUFFER,
> + .index = -1,
> +};
> +
> +void hsu_early_printk(const char *fmt, ...)
> +{
> + char buf[512];
> + int n;
> + va_list ap;
> +
> + va_start(ap, fmt);
> + n = vscnprintf(buf, 512, fmt, ap);
> + va_end(ap);
> +
> + early_hsu_console.write(&early_mrst_console, buf, n);
> +}
Instead of this hack that duplicates much of early_printk() please add
something like:
extern void __earlyprintk(struct console *con, ...)
and then hsa_early_printk() becomes:
#define hsu_early_printk(x...) __early_printk(&earlymrst_console, x...)
... or so - and other subsystems may make use of it as well, to
implement their own special unconditional-printout routines.
Thanks,
Ingo
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