diff options
Diffstat (limited to 'arch/arm/plat-omap/counter_32k.c')
| -rw-r--r-- | arch/arm/plat-omap/counter_32k.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c new file mode 100644 index 00000000..f7fed608 --- /dev/null +++ b/arch/arm/plat-omap/counter_32k.c @@ -0,0 +1,207 @@ +/* + * OMAP 32ksynctimer/counter_32k-related code + * + * Copyright (C) 2009 Texas Instruments + * Copyright (C) 2010 Nokia Corporation + * Tony Lindgren <tony@atomide.com> + * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * NOTE: This timer is not the same timer as the old OMAP1 MPU timer. + */ +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/sched.h> + +#include <asm/sched_clock.h> + +#include <plat/common.h> +#include <plat/board.h> + +#include <plat/clock.h> + + +/* + * 32KHz clocksource ... always available, on pretty most chips except + * OMAP 730 and 1510. Other timers could be used as clocksources, with + * higher resolution in free-running counter modes (e.g. 12 MHz xtal), + * but systems won't necessarily want to spend resources that way. + */ + +#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410 + +#include <linux/clocksource.h> + +/* + * offset_32k holds the init time counter value. It is then subtracted + * from every counter read to achieve a counter that counts time from the + * kernel boot (needed for sched_clock()). + */ +static u32 offset_32k __read_mostly; + +#ifdef CONFIG_ARCH_OMAP16XX +static cycle_t notrace omap16xx_32k_read(struct clocksource *cs) +{ + return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED) - offset_32k; +} +#else +#define omap16xx_32k_read NULL +#endif + +#ifdef CONFIG_SOC_OMAP2420 +static cycle_t notrace omap2420_32k_read(struct clocksource *cs) +{ + return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10) - offset_32k; +} +#else +#define omap2420_32k_read NULL +#endif + +#ifdef CONFIG_SOC_OMAP2430 +static cycle_t notrace omap2430_32k_read(struct clocksource *cs) +{ + return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10) - offset_32k; +} +#else +#define omap2430_32k_read NULL +#endif + +#ifdef CONFIG_ARCH_OMAP3 +static cycle_t notrace omap34xx_32k_read(struct clocksource *cs) +{ + return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10) - offset_32k; +} +#else +#define omap34xx_32k_read NULL +#endif + +#ifdef CONFIG_ARCH_OMAP4 +static cycle_t notrace omap44xx_32k_read(struct clocksource *cs) +{ + return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10) - offset_32k; +} +#else +#define omap44xx_32k_read NULL +#endif + +/* + * Kernel assumes that sched_clock can be called early but may not have + * things ready yet. + */ +static cycle_t notrace omap_32k_read_dummy(struct clocksource *cs) +{ + return 0; +} + +static struct clocksource clocksource_32k = { + .name = "32k_counter", + .rating = 250, + .read = omap_32k_read_dummy, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +/* + * Returns current time from boot in nsecs. It's OK for this to wrap + * around for now, as it's just a relative time stamp. + */ +static DEFINE_CLOCK_DATA(cd); + +/* + * Constants generated by clocks_calc_mult_shift(m, s, 32768, NSEC_PER_SEC, 60). + * This gives a resolution of about 30us and a wrap period of about 36hrs. + */ +#define SC_MULT 4000000000u +#define SC_SHIFT 17 + +static inline unsigned long long notrace _omap_32k_sched_clock(void) +{ + u32 cyc = clocksource_32k.read(&clocksource_32k); + return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT); +} + +#ifndef CONFIG_OMAP_MPU_TIMER +unsigned long long notrace sched_clock(void) +{ + return _omap_32k_sched_clock(); +} +#else +unsigned long long notrace omap_32k_sched_clock(void) +{ + return _omap_32k_sched_clock(); +} +#endif + +static void notrace omap_update_sched_clock(void) +{ + u32 cyc = clocksource_32k.read(&clocksource_32k); + update_sched_clock(&cd, cyc, (u32)~0); +} + +/** + * read_persistent_clock - Return time from a persistent clock. + * + * Reads the time from a source which isn't disabled during PM, the + * 32k sync timer. Convert the cycles elapsed since last read into + * nsecs and adds to a monotonically increasing timespec. + */ +static struct timespec persistent_ts; +static cycles_t cycles, last_cycles; +void read_persistent_clock(struct timespec *ts) +{ + unsigned long long nsecs; + cycles_t delta; + struct timespec *tsp = &persistent_ts; + + last_cycles = cycles; + cycles = clocksource_32k.read(&clocksource_32k); + delta = cycles - last_cycles; + + nsecs = clocksource_cyc2ns(delta, + clocksource_32k.mult, clocksource_32k.shift); + + timespec_add_ns(tsp, nsecs); + *ts = *tsp; +} + +int __init omap_init_clocksource_32k(void) +{ + static char err[] __initdata = KERN_ERR + "%s: can't register clocksource!\n"; + + if (cpu_is_omap16xx() || cpu_class_is_omap2()) { + struct clk *sync_32k_ick; + + if (cpu_is_omap16xx()) + clocksource_32k.read = omap16xx_32k_read; + else if (cpu_is_omap2420()) + clocksource_32k.read = omap2420_32k_read; + else if (cpu_is_omap2430()) + clocksource_32k.read = omap2430_32k_read; + else if (cpu_is_omap34xx()) + clocksource_32k.read = omap34xx_32k_read; + else if (cpu_is_omap44xx()) + clocksource_32k.read = omap44xx_32k_read; + else + return -ENODEV; + + sync_32k_ick = clk_get(NULL, "omap_32ksync_ick"); + if (!IS_ERR(sync_32k_ick)) + clk_enable(sync_32k_ick); + + offset_32k = clocksource_32k.read(&clocksource_32k); + + if (clocksource_register_hz(&clocksource_32k, 32768)) + printk(err, clocksource_32k.name); + + init_fixed_sched_clock(&cd, omap_update_sched_clock, 32, + 32768, SC_MULT, SC_SHIFT); + } + return 0; +} |