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authorJens Rottmann <JRottmann@LiPPERTEmbedded.de>2008-08-04 14:40:16 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-15 17:12:32 +0200
commit0d5cdc97e242a5589e5dca23277675f4b4482490 (patch)
tree8eea2c2db4541a05114dd9fb61e782a0e5d13458 /arch
parentb635acec48bcaa9183fcbf4e3955616b0d4119b5 (diff)
x86, geode-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> Cc: Andres Salomon <dilinger@debian.org> Cc: linux-geode@bombadil.infradead.org Cc: Jordan Crouse <jordan.crouse@amd.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/mfgpt_32.c52
1 files changed, 37 insertions, 15 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c
index 07c0f828f48..3b599518c32 100644
--- a/arch/x86/kernel/mfgpt_32.c
+++ b/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 +159,48 @@ int geode_mfgpt_toggle_event(int timer, int cmp, int event, int enable)
}
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))
+ /*
+ * Unfortunately, MFGPTs come in pairs sharing their IRQ lines. If VSA
+ * is using the same CMP of the timer's Siamese twin, the IRQ is set to
+ * 2, and we mustn't use nor change it.
+ * XXX: Likewise, 2 Linux drivers might clash if the 2nd overwrites the
+ * IRQ of the 1st. This can only happen if forcing an IRQ, calling this
+ * with *irq==0 is safe. Currently there _are_ no 2 drivers.
+ */
+ rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
+ shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer % 4) * 4;
+ if (((zsel >> shift) & 0xF) == 2)
return -EIO;
- rdmsr(MSR_PIC_ZSEL_LOW, val, dummy);
+ /* Choose IRQ: if none supplied, keep IRQ already set or use default */
+ if (!*irq)
+ *irq = (zsel >> shift) & 0xF;
+ if (!*irq)
+ *irq = MFGPT_DEFAULT_IRQ;
- offset = (timer % 4) * 4;
-
- 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 +263,7 @@ EXPORT_SYMBOL_GPL(geode_mfgpt_alloc_timer);
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 +367,7 @@ 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 +395,14 @@ 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;