Commit 8f36881b authored by Andres Salomon's avatar Andres Salomon Committed by Thomas Gleixner

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: default avatarJordan Crouse <jordan.crouse@amd.com>
Signed-off-by: default avatarAndres 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 83d7384f
......@@ -1009,6 +1009,10 @@ and is between 256 and 4096 characters. It is defined in the file
meye.*= [HW] Set MotionEye Camera parameters
See Documentation/video4linux/meye.txt.
mfgpt_irq= [IA-32] Specify the IRQ to use for the
Multi-Function General Purpose Timers on AMD Geode
platforms.
mga= [HW,DRM]
mousedev.tap_time=
......
......@@ -1206,6 +1206,16 @@ config SCx200HR_TIMER
processor goes idle (as is done by the scheduler). The
other workaround is idle=poll boot option.
config GEODE_MFGPT_TIMER
bool "Geode Multi-Function General Purpose Timer (MFGPT) events"
depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
default y
help
This driver provides a clock event source based on the MFGPT
timer(s) in the CS5535 and CS5536 companion chip for the geode.
MFGPTs have a better resolution and max interval than the
generic PIT, and are suitable for use as high-res timers.
config K8_NB
def_bool y
depends on AGP_AMD64
......
......@@ -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
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