2f0778afac
sched_clock() is yet another blocker on the road to the single image. This patch implements an idea by Russell King: http://www.spinics.net/lists/linux-omap/msg49561.html Instead of asking the platform to implement both sched_clock() itself and the rollover callback, simply register a read() function, and let the ARM code care about sched_clock() itself, the conversion to ns and the rollover. sched_clock() uses this read() function as an indirection to the platform code. If the platform doesn't provide a read(), the code falls back to the jiffy counter (just like the default sched_clock). This allow some simplifications and possibly some footprint gain when multiple platforms are compiled in. Among the drawbacks, the removal of the *_fixed_sched_clock optimization which could negatively impact some platforms (sa1100, tegra, versatile and omap). Tested on 11MPCore, OMAP4 and Tegra. Cc: Imre Kaloz <kaloz@openwrt.org> Cc: Eric Miao <eric.y.miao@gmail.com> Cc: Colin Cross <ccross@android.com> Cc: Erik Gilling <konkers@android.com> Cc: Olof Johansson <olof@lixom.net> Cc: Sascha Hauer <kernel@pengutronix.de> Cc: Alessandro Rubini <rubini@unipv.it> Cc: STEricsson <STEricsson_nomadik_linux@list.st.com> Cc: Lennert Buytenhek <kernel@wantstofly.org> Cc: Ben Dooks <ben-linux@fluff.org> Tested-by: Jamie Iles <jamie@jamieiles.com> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Krzysztof Halasa <khc@pm.waw.pl> Acked-by: Kukjin Kim <kgene.kim@samsung.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
121 lines
3.3 KiB
C
121 lines
3.3 KiB
C
/*
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* OMAP 32ksynctimer/counter_32k-related code
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*
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* Copyright (C) 2009 Texas Instruments
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* Copyright (C) 2010 Nokia Corporation
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* Tony Lindgren <tony@atomide.com>
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* Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/clocksource.h>
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#include <asm/sched_clock.h>
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#include <plat/common.h>
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#include <plat/board.h>
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#include <plat/clock.h>
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/*
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* 32KHz clocksource ... always available, on pretty most chips except
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* OMAP 730 and 1510. Other timers could be used as clocksources, with
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* higher resolution in free-running counter modes (e.g. 12 MHz xtal),
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* but systems won't necessarily want to spend resources that way.
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*/
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static void __iomem *timer_32k_base;
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#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
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static u32 notrace omap_32k_read_sched_clock(void)
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{
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return timer_32k_base ? __raw_readl(timer_32k_base) : 0;
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}
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/**
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* read_persistent_clock - Return time from a persistent clock.
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*
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* Reads the time from a source which isn't disabled during PM, the
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* 32k sync timer. Convert the cycles elapsed since last read into
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* nsecs and adds to a monotonically increasing timespec.
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*/
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static struct timespec persistent_ts;
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static cycles_t cycles, last_cycles;
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static unsigned int persistent_mult, persistent_shift;
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void read_persistent_clock(struct timespec *ts)
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{
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unsigned long long nsecs;
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cycles_t delta;
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struct timespec *tsp = &persistent_ts;
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last_cycles = cycles;
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cycles = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
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delta = cycles - last_cycles;
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nsecs = clocksource_cyc2ns(delta, persistent_mult, persistent_shift);
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timespec_add_ns(tsp, nsecs);
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*ts = *tsp;
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}
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int __init omap_init_clocksource_32k(void)
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{
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static char err[] __initdata = KERN_ERR
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"%s: can't register clocksource!\n";
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if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
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u32 pbase;
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unsigned long size = SZ_4K;
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void __iomem *base;
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struct clk *sync_32k_ick;
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if (cpu_is_omap16xx()) {
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pbase = OMAP16XX_TIMER_32K_SYNCHRONIZED;
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size = SZ_1K;
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} else if (cpu_is_omap2420())
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pbase = OMAP2420_32KSYNCT_BASE + 0x10;
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else if (cpu_is_omap2430())
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pbase = OMAP2430_32KSYNCT_BASE + 0x10;
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else if (cpu_is_omap34xx())
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pbase = OMAP3430_32KSYNCT_BASE + 0x10;
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else if (cpu_is_omap44xx())
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pbase = OMAP4430_32KSYNCT_BASE + 0x10;
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else
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return -ENODEV;
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/* For this to work we must have a static mapping in io.c for this area */
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base = ioremap(pbase, size);
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if (!base)
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return -ENODEV;
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sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
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if (!IS_ERR(sync_32k_ick))
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clk_enable(sync_32k_ick);
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timer_32k_base = base;
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/*
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* 120000 rough estimate from the calculations in
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* __clocksource_updatefreq_scale.
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*/
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clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
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32768, NSEC_PER_SEC, 120000);
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if (clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
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clocksource_mmio_readl_up))
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printk(err, "32k_counter");
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setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
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}
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return 0;
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}
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