diff options
author | Andres Salomon <dilinger@queued.net> | 2007-10-12 23:04:06 +0200 |
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committer | Thomas Gleixner <tglx@inhelltoy.tec.linutronix.de> | 2007-10-12 23:04:06 +0200 |
commit | 8f36881b3c972ebc019195692849f22488f9c0a3 (patch) | |
tree | dd14aeb1fdb6f516f154a276d21f82c58d5e35b3 /arch/x86/kernel | |
parent | 83d7384f8d4aa216b49cf9cb286ea743054b119f (diff) | |
download | linux-8f36881b3c972ebc019195692849f22488f9c0a3.tar.bz2 |
x86: Geode MFGPT clock event device support
Add support for an MFGPT clock event device; this allows us to use MFGPTs as
the basis for high-resolution timers.
Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r-- | arch/x86/kernel/mfgpt_32.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c index 3a63a2dd8d27..0ab680f2d9db 100644 --- a/arch/x86/kernel/mfgpt_32.c +++ b/arch/x86/kernel/mfgpt_32.c @@ -48,6 +48,12 @@ static struct mfgpt_timer_t { #define MFGPT_HZ (32000 / MFGPT_DIVISOR) #define MFGPT_PERIODIC (MFGPT_HZ / HZ) +#ifdef CONFIG_GEODE_MFGPT_TIMER +static int __init mfgpt_timer_setup(void); +#else +#define mfgpt_timer_setup() (0) +#endif + /* Allow for disabling of MFGPTs */ static int disable; static int __init mfgpt_disable(char *s) @@ -82,6 +88,9 @@ int __init geode_mfgpt_detect(void) } } + /* set up clock event device, if desired */ + i = mfgpt_timer_setup(); + return count; } @@ -195,3 +204,159 @@ int geode_mfgpt_alloc_timer(int timer, int domain, struct module *owner) return -1; } + +#ifdef CONFIG_GEODE_MFGPT_TIMER + +/* + * The MFPGT timers on the CS5536 provide us with suitable timers to use + * as clock event sources - not as good as a HPET or APIC, but certainly + * better then the PIT. This isn't a general purpose MFGPT driver, but + * a simplified one designed specifically to act as a clock event source. + * For full details about the MFGPT, please consult the CS5536 data sheet. + */ + +#include <linux/clocksource.h> +#include <linux/clockchips.h> + +static unsigned int mfgpt_tick_mode = CLOCK_EVT_MODE_SHUTDOWN; +static u16 mfgpt_event_clock; + +static int irq = 7; +static int __init mfgpt_setup(char *str) +{ + get_option(&str, &irq); + return 1; +} +__setup("mfgpt_irq=", mfgpt_setup); + +static inline void mfgpt_disable_timer(u16 clock) +{ + u16 val = geode_mfgpt_read(clock, MFGPT_REG_SETUP); + geode_mfgpt_write(clock, MFGPT_REG_SETUP, val & ~MFGPT_SETUP_CNTEN); +} + +static int mfgpt_next_event(unsigned long, struct clock_event_device *); +static void mfgpt_set_mode(enum clock_event_mode, struct clock_event_device *); + +static struct clock_event_device mfgpt_clockevent = { + .name = "mfgpt-timer", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_mode = mfgpt_set_mode, + .set_next_event = mfgpt_next_event, + .rating = 250, + .cpumask = CPU_MASK_ALL, + .shift = 32 +}; + +static inline void mfgpt_start_timer(u16 clock, u16 delta) +{ + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_CMP2, (u16) delta); + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0); + + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, + MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2); +} + +static void mfgpt_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + mfgpt_disable_timer(mfgpt_event_clock); + + if (mode == CLOCK_EVT_MODE_PERIODIC) + mfgpt_start_timer(mfgpt_event_clock, MFGPT_PERIODIC); + + mfgpt_tick_mode = mode; +} + +static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt) +{ + mfgpt_start_timer(mfgpt_event_clock, delta); + return 0; +} + +/* Assume (foolishly?), that this interrupt was due to our tick */ + +static irqreturn_t mfgpt_tick(int irq, void *dev_id) +{ + if (mfgpt_tick_mode == CLOCK_EVT_MODE_SHUTDOWN) + return IRQ_HANDLED; + + /* Turn off the clock */ + mfgpt_disable_timer(mfgpt_event_clock); + + /* Clear the counter */ + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0); + + /* Restart the clock in periodic mode */ + + if (mfgpt_tick_mode == CLOCK_EVT_MODE_PERIODIC) { + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, + MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2); + } + + mfgpt_clockevent.event_handler(&mfgpt_clockevent); + return IRQ_HANDLED; +} + +static struct irqaction mfgptirq = { + .handler = mfgpt_tick, + .flags = IRQF_DISABLED | IRQF_NOBALANCING, + .mask = CPU_MASK_NONE, + .name = "mfgpt-timer" +}; + +static int __init mfgpt_timer_setup(void) +{ + int timer, ret; + u16 val; + + timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING, + THIS_MODULE); + if (timer < 0) { + printk(KERN_ERR + "mfgpt-timer: Could not allocate a MFPGT timer\n"); + return -ENODEV; + } + + mfgpt_event_clock = timer; + /* Set the clock scale and enable the event mode for CMP2 */ + val = MFGPT_SCALE | (3 << 8); + + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val); + + /* Set up the IRQ on the MFGPT side */ + 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; + } + + /* And register it with the kernel */ + ret = setup_irq(irq, &mfgptirq); + + if (ret) { + printk(KERN_ERR + "mfgpt-timer: Unable to set up the interrupt.\n"); + goto err; + } + + /* Set up the clock event */ + mfgpt_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC, 32); + mfgpt_clockevent.min_delta_ns = clockevent_delta2ns(0xF, + &mfgpt_clockevent); + mfgpt_clockevent.max_delta_ns = clockevent_delta2ns(0xFFFE, + &mfgpt_clockevent); + + printk(KERN_INFO + "mfgpt-timer: registering the MFGT timer as a clock event.\n"); + clockevents_register_device(&mfgpt_clockevent); + + return 0; + +err: + 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; +} + +#endif |