x86: Geode MFGPT clock event device support (8f36881b) · Commits · e / devices / android_kernel_xiaomi_markw

Documentation/kernel-parameters.txt

+4 −0

Original line number	Diff line number	Diff line
		@@ -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=

arch/i386/Kconfig

+10 −0

Original line number	Diff line number	Diff line
		@@ -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

arch/x86/kernel/mfgpt_32.c

+165 −0

Original line number	Diff line number	Diff line
		@@ -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