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SubjectRe: MFGPT driver inhibits boot on some boards
On 01/08/08 17:25 +0200, Jens Rottmann wrote:
> mfgpt: check IRQ before using MFGPT as clocksource
>
> Adds a simple IRQ autodetection to the AMD Geode MFGPT driver, and more
> importantly, adds some checks, if IRQs can actually be received on the
> chosen line. This fixes cases where MFGPT is selected as clocksource
> though not producing any ticks, so the kernel simply starves during
> boot.
>
> Signed-off-by: Jens Rottmann <JRottmann@LiPPERTEmbedded.de>

One comment below - otherwise, I reviewed it and it looks good, but
I haven't tried it.

Jordan

> ---
>
> --- linux-2.6.26/include/asm-x86/geode.h
> +++ mfgpt-irq-fix/include/asm-x86/geode.h
> @@ -50,6 +50,7 @@
> #define MSR_PIC_YSEL_HIGH 0x51400021
> #define MSR_PIC_ZSEL_LOW 0x51400022
> #define MSR_PIC_ZSEL_HIGH 0x51400023
> +#define MSR_PIC_IRQM_LPC 0x51400025
>
> #define MSR_MFGPT_IRQ 0x51400028
> #define MSR_MFGPT_NR 0x51400029
> @@ -237,7 +238,7 @@
> }
>
> extern int geode_mfgpt_toggle_event(int timer, int cmp, int event, int enable);
> -extern int geode_mfgpt_set_irq(int timer, int cmp, int irq, int enable);
> +extern int geode_mfgpt_set_irq(int timer, int cmp, int *irq, int enable);
> extern int geode_mfgpt_alloc_timer(int timer, int domain);
>
> #define geode_mfgpt_setup_irq(t, c, i) geode_mfgpt_set_irq((t), (c), (i), 1)
> --- linux-2.6.26/arch/x86/kernel/mfgpt_32.c
> +++ mfgpt-irq-fix/arch/x86/kernel/mfgpt_32.c
> @@ -33,6 +33,8 @@
> #include <linux/module.h>
> #include <asm/geode.h>
>
> +#define MFGPT_DEFAULT_IRQ 7
> +
> static struct mfgpt_timer_t {
> unsigned int avail:1;
> } mfgpt_timers[MFGPT_MAX_TIMERS];
> @@ -157,29 +159,41 @@
> }
> EXPORT_SYMBOL_GPL(geode_mfgpt_toggle_event);
>
> -int geode_mfgpt_set_irq(int timer, int cmp, int irq, int enable)
> +int geode_mfgpt_set_irq(int timer, int cmp, int *irq, int enable)
> {
> - u32 val, dummy;
> - int offset;
> + u32 zsel, lpc, dummy;
> + int shift;
>
> if (timer < 0 || timer >= MFGPT_MAX_TIMERS)
> return -EIO;
>
> - if (geode_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
> + /* IRQ already set to 2 means VSA is using the timer's Siamese twin */

Please make this more descriptive - something like this:
/* If the IRQ is set to 2, then VSA is using the other timer in the pair */
Siamese twin might be confusing.

> + shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer % 4) * 4;
> + rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
> + if (((zsel >> shift) & 0xF) == 2)
> return -EIO;

> - rdmsr(MSR_PIC_ZSEL_LOW, val, dummy);
> -
> - offset = (timer % 4) * 4;
> + /* Choose IRQ: if none supplied, keep IRQ already set or use default */
> + if (!*irq)
> + *irq = (zsel >> shift) & 0xF;
> + if (!*irq)
> + *irq = MFGPT_DEFAULT_IRQ;

> - val &= ~((0xF << offset) | (0xF << (offset + 16)));
> + /* Can't use IRQ if it's 0 (=disabled), 2, or routed to LPC */
> + if (*irq < 1 || *irq == 2 || *irq > 15)
> + return -EIO;
> + rdmsr(MSR_PIC_IRQM_LPC, lpc, dummy);
> + if (lpc & (1 << *irq))
> + return -EIO;

> + /* All chosen and checked - go for it */
> + if (geode_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
> + return -EIO;
> if (enable) {
> - val |= (irq & 0x0F) << (offset);
> - val |= (irq & 0x0F) << (offset + 16);
> + zsel = (zsel & ~(0xF << shift)) | (*irq << shift);
> + wrmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
> }
>
> - wrmsr(MSR_PIC_ZSEL_LOW, val, dummy);
> return 0;
> }
>
> @@ -242,7 +256,7 @@
> static unsigned int mfgpt_tick_mode = CLOCK_EVT_MODE_SHUTDOWN;
> static u16 mfgpt_event_clock;
>
> -static int irq = 7;
> +static int irq;
> static int __init mfgpt_setup(char *str)
> {
> get_option(&str, &irq);
> @@ -346,7 +360,7 @@ int __init mfgpt_timer_setup(void)
> mfgpt_event_clock = timer;
>
> /* Set up the IRQ on the MFGPT side */
> - if (geode_mfgpt_setup_irq(mfgpt_event_clock, MFGPT_CMP2, irq)) {
> + if (geode_mfgpt_setup_irq(mfgpt_event_clock, MFGPT_CMP2, &irq)) {
> printk(KERN_ERR "mfgpt-timer: Could not set up IRQ %d\n", irq);
> return -EIO;
> }
> @@ -374,13 +388,14 @@ int __init mfgpt_timer_setup(void)
> &mfgpt_clockevent);
>
> printk(KERN_INFO
> - "mfgpt-timer: registering the MFGPT timer as a clock event.\n");
> + "mfgpt-timer: Registering MFGPT timer %d as a clock event, using IRQ %d\n",
> + timer, irq);
> clockevents_register_device(&mfgpt_clockevent);
>
> return 0;
>
> err:
> - geode_mfgpt_release_irq(mfgpt_event_clock, MFGPT_CMP2, irq);
> + geode_mfgpt_release_irq(mfgpt_event_clock, MFGPT_CMP2, &irq);
> printk(KERN_ERR
> "mfgpt-timer: Unable to set up the MFGPT clock source\n");
> return -EIO;
> _
>
>



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