diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 9 | ||||
| -rw-r--r-- | arch/arm/mach-shmobile/Kconfig | 6 | ||||
| -rw-r--r-- | drivers/clocksource/Makefile | 1 | ||||
| -rw-r--r-- | drivers/clocksource/em_sti.c | 406 | ||||
| -rw-r--r-- | include/linux/clockchips.h | 1 | ||||
| -rw-r--r-- | kernel/time/clockevents.c | 3 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 18 |
7 files changed, 442 insertions, 2 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index c45513d806ab..a92c5ebf373e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2543,6 +2543,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. sched_debug [KNL] Enables verbose scheduler debug messages. + skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate + xtime_lock contention on larger systems, and/or RCU lock + contention on all systems with CONFIG_MAXSMP set. + Format: { "0" | "1" } + 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" + 1 -- enable. + Note: increases power consumption, thus should only be + enabled if running jitter sensitive (HPC/RT) workloads. + security= [SECURITY] Choose a security module to enable at boot. If this boot parameter is not specified, only the first security module asking for security registration will be diff --git a/arch/arm/mach-shmobile/Kconfig b/arch/arm/mach-shmobile/Kconfig index f31383c32f9c..df33909205e2 100644 --- a/arch/arm/mach-shmobile/Kconfig +++ b/arch/arm/mach-shmobile/Kconfig @@ -186,6 +186,12 @@ config SH_TIMER_TMU help This enables build of the TMU timer driver. +config EM_TIMER_STI + bool "STI timer driver" + default y + help + This enables build of the STI timer driver. + endmenu config SH_CLK_CPG diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index 8d81a1d32653..dd3e661a124d 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -6,6 +6,7 @@ obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC) += cs5535-clockevt.o obj-$(CONFIG_SH_TIMER_CMT) += sh_cmt.o obj-$(CONFIG_SH_TIMER_MTU2) += sh_mtu2.o obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.o +obj-$(CONFIG_EM_TIMER_STI) += em_sti.o obj-$(CONFIG_CLKBLD_I8253) += i8253.o obj-$(CONFIG_CLKSRC_MMIO) += mmio.o obj-$(CONFIG_DW_APB_TIMER) += dw_apb_timer.o diff --git a/drivers/clocksource/em_sti.c b/drivers/clocksource/em_sti.c new file mode 100644 index 000000000000..372051d1bba8 --- /dev/null +++ b/drivers/clocksource/em_sti.c @@ -0,0 +1,406 @@ +/* + * Emma Mobile Timer Support - STI + * + * Copyright (C) 2012 Magnus Damm + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <linux/init.h> +#include <linux/platform_device.h> +#include <linux/spinlock.h> +#include <linux/interrupt.h> +#include <linux/ioport.h> +#include <linux/io.h> +#include <linux/clk.h> +#include <linux/irq.h> +#include <linux/err.h> +#include <linux/delay.h> +#include <linux/clocksource.h> +#include <linux/clockchips.h> +#include <linux/slab.h> +#include <linux/module.h> + +enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; + +struct em_sti_priv { + void __iomem *base; + struct clk *clk; + struct platform_device *pdev; + unsigned int active[USER_NR]; + unsigned long rate; + raw_spinlock_t lock; + struct clock_event_device ced; + struct clocksource cs; +}; + +#define STI_CONTROL 0x00 +#define STI_COMPA_H 0x10 +#define STI_COMPA_L 0x14 +#define STI_COMPB_H 0x18 +#define STI_COMPB_L 0x1c +#define STI_COUNT_H 0x20 +#define STI_COUNT_L 0x24 +#define STI_COUNT_RAW_H 0x28 +#define STI_COUNT_RAW_L 0x2c +#define STI_SET_H 0x30 +#define STI_SET_L 0x34 +#define STI_INTSTATUS 0x40 +#define STI_INTRAWSTATUS 0x44 +#define STI_INTENSET 0x48 +#define STI_INTENCLR 0x4c +#define STI_INTFFCLR 0x50 + +static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) +{ + return ioread32(p->base + offs); +} + +static inline void em_sti_write(struct em_sti_priv *p, int offs, + unsigned long value) +{ + iowrite32(value, p->base + offs); +} + +static int em_sti_enable(struct em_sti_priv *p) +{ + int ret; + + /* enable clock */ + ret = clk_enable(p->clk); + if (ret) { + dev_err(&p->pdev->dev, "cannot enable clock\n"); + return ret; + } + + /* configure channel, periodic mode and maximum timeout */ + p->rate = clk_get_rate(p->clk); + + /* reset the counter */ + em_sti_write(p, STI_SET_H, 0x40000000); + em_sti_write(p, STI_SET_L, 0x00000000); + + /* mask and clear pending interrupts */ + em_sti_write(p, STI_INTENCLR, 3); + em_sti_write(p, STI_INTFFCLR, 3); + + /* enable updates of counter registers */ + em_sti_write(p, STI_CONTROL, 1); + + return 0; +} + +static void em_sti_disable(struct em_sti_priv *p) +{ + /* mask interrupts */ + em_sti_write(p, STI_INTENCLR, 3); + + /* stop clock */ + clk_disable(p->clk); +} + +static cycle_t em_sti_count(struct em_sti_priv *p) +{ + cycle_t ticks; + unsigned long flags; + + /* the STI hardware buffers the 48-bit count, but to + * break it out into two 32-bit access the registers + * must be accessed in a certain order. + * Always read STI_COUNT_H before STI_COUNT_L. + */ + raw_spin_lock_irqsave(&p->lock, flags); + ticks = (cycle_t)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32; + ticks |= em_sti_read(p, STI_COUNT_L); + raw_spin_unlock_irqrestore(&p->lock, flags); + + return ticks; +} + +static cycle_t em_sti_set_next(struct em_sti_priv *p, cycle_t next) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&p->lock, flags); + + /* mask compare A interrupt */ + em_sti_write(p, STI_INTENCLR, 1); + + /* update compare A value */ + em_sti_write(p, STI_COMPA_H, next >> 32); + em_sti_write(p, STI_COMPA_L, next & 0xffffffff); + + /* clear compare A interrupt source */ + em_sti_write(p, STI_INTFFCLR, 1); + + /* unmask compare A interrupt */ + em_sti_write(p, STI_INTENSET, 1); + + raw_spin_unlock_irqrestore(&p->lock, flags); + + return next; +} + +static irqreturn_t em_sti_interrupt(int irq, void *dev_id) +{ + struct em_sti_priv *p = dev_id; + + p->ced.event_handler(&p->ced); + return IRQ_HANDLED; +} + +static int em_sti_start(struct em_sti_priv *p, unsigned int user) +{ + unsigned long flags; + int used_before; + int ret = 0; + + raw_spin_lock_irqsave(&p->lock, flags); + used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; + if (!used_before) + ret = em_sti_enable(p); + + if (!ret) + p->active[user] = 1; + raw_spin_unlock_irqrestore(&p->lock, flags); + + return ret; +} + +static void em_sti_stop(struct em_sti_priv *p, unsigned int user) +{ + unsigned long flags; + int used_before, used_after; + + raw_spin_lock_irqsave(&p->lock, flags); + used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; + p->active[user] = 0; + used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; + + if (used_before && !used_after) + em_sti_disable(p); + raw_spin_unlock_irqrestore(&p->lock, flags); +} + +static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) +{ + return container_of(cs, struct em_sti_priv, cs); +} + +static cycle_t em_sti_clocksource_read(struct clocksource *cs) +{ + return em_sti_count(cs_to_em_sti(cs)); +} + +static int em_sti_clocksource_enable(struct clocksource *cs) +{ + int ret; + struct em_sti_priv *p = cs_to_em_sti(cs); + + ret = em_sti_start(p, USER_CLOCKSOURCE); + if (!ret) + __clocksource_updatefreq_hz(cs, p->rate); + return ret; +} + +static void em_sti_clocksource_disable(struct clocksource *cs) +{ + em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE); +} + +static void em_sti_clocksource_resume(struct clocksource *cs) +{ + em_sti_clocksource_enable(cs); +} + +static int em_sti_register_clocksource(struct em_sti_priv *p) +{ + struct clocksource *cs = &p->cs; + + memset(cs, 0, sizeof(*cs)); + cs->name = dev_name(&p->pdev->dev); + cs->rating = 200; + cs->read = em_sti_clocksource_read; + cs->enable = em_sti_clocksource_enable; + cs->disable = em_sti_clocksource_disable; + cs->suspend = em_sti_clocksource_disable; + cs->resume = em_sti_clocksource_resume; + cs->mask = CLOCKSOURCE_MASK(48); + cs->flags = CLOCK_SOURCE_IS_CONTINUOUS; + + dev_info(&p->pdev->dev, "used as clock source\n"); + + /* Register with dummy 1 Hz value, gets updated in ->enable() */ + clocksource_register_hz(cs, 1); + return 0; +} + +static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced) +{ + return container_of(ced, struct em_sti_priv, ced); +} + +static void em_sti_clock_event_mode(enum clock_event_mode mode, + struct clock_event_device *ced) +{ + struct em_sti_priv *p = ced_to_em_sti(ced); + + /* deal with old setting first */ + switch (ced->mode) { + case CLOCK_EVT_MODE_ONESHOT: + em_sti_stop(p, USER_CLOCKEVENT); + break; + default: + break; + } + + switch (mode) { + case CLOCK_EVT_MODE_ONESHOT: + dev_info(&p->pdev->dev, "used for oneshot clock events\n"); + em_sti_start(p, USER_CLOCKEVENT); + clockevents_config(&p->ced, p->rate); + break; + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + em_sti_stop(p, USER_CLOCKEVENT); + break; + default: + break; + } +} + +static int em_sti_clock_event_next(unsigned long delta, + struct clock_event_device *ced) +{ + struct em_sti_priv *p = ced_to_em_sti(ced); + cycle_t next; + int safe; + + next = em_sti_set_next(p, em_sti_count(p) + delta); + safe = em_sti_count(p) < (next - 1); + + return !safe; +} + +static void em_sti_register_clockevent(struct em_sti_priv *p) +{ + struct clock_event_device *ced = &p->ced; + + memset(ced, 0, sizeof(*ced)); + ced->name = dev_name(&p->pdev->dev); + ced->features = CLOCK_EVT_FEAT_ONESHOT; + ced->rating = 200; + ced->cpumask = cpumask_of(0); + ced->set_next_event = em_sti_clock_event_next; + ced->set_mode = em_sti_clock_event_mode; + + dev_info(&p->pdev->dev, "used for clock events\n"); + + /* Register with dummy 1 Hz value, gets updated in ->set_mode() */ + clockevents_config_and_register(ced, 1, 2, 0xffffffff); +} + +static int __devinit em_sti_probe(struct platform_device *pdev) +{ + struct em_sti_priv *p; + struct resource *res; + int irq, ret; + + p = kzalloc(sizeof(*p), GFP_KERNEL); + if (p == NULL) { + dev_err(&pdev->dev, "failed to allocate driver data\n"); + ret = -ENOMEM; + goto err0; + } + + p->pdev = pdev; + platform_set_drvdata(pdev, p); + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(&pdev->dev, "failed to get I/O memory\n"); + ret = -EINVAL; + goto err0; + } + + irq = platform_get_irq(pdev, 0); + if (irq < 0) { + dev_err(&pdev->dev, "failed to get irq\n"); + ret = -EINVAL; + goto err0; + } + + /* map memory, let base point to the STI instance */ + p->base = ioremap_nocache(res->start, resource_size(res)); + if (p->base == NULL) { + dev_err(&pdev->dev, "failed to remap I/O memory\n"); + ret = -ENXIO; + goto err0; + } + + /* get hold of clock */ + p->clk = clk_get(&pdev->dev, "sclk"); + if (IS_ERR(p->clk)) { + dev_err(&pdev->dev, "cannot get clock\n"); + ret = PTR_ERR(p->clk); + goto err1; + } + + if (request_irq(irq, em_sti_interrupt, + IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, + dev_name(&pdev->dev), p)) { + dev_err(&pdev->dev, "failed to request low IRQ\n"); + ret = -ENOENT; + goto err2; + } + + raw_spin_lock_init(&p->lock); + em_sti_register_clockevent(p); + em_sti_register_clocksource(p); + return 0; + +err2: + clk_put(p->clk); +err1: + iounmap(p->base); +err0: + kfree(p); + return ret; +} + +static int __devexit em_sti_remove(struct platform_device *pdev) +{ + return -EBUSY; /* cannot unregister clockevent and clocksource */ +} + +static const struct of_device_id em_sti_dt_ids[] __devinitconst = { + { .compatible = "renesas,em-sti", }, + {}, +}; +MODULE_DEVICE_TABLE(of, em_sti_dt_ids); + +static struct platform_driver em_sti_device_driver = { + .probe = em_sti_probe, + .remove = __devexit_p(em_sti_remove), + .driver = { + .name = "em_sti", + .of_match_table = em_sti_dt_ids, + } +}; + +module_platform_driver(em_sti_device_driver); + +MODULE_AUTHOR("Magnus Damm"); +MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver"); +MODULE_LICENSE("GPL v2"); diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h index 81e803e90aa4..acba894374a1 100644 --- a/include/linux/clockchips.h +++ b/include/linux/clockchips.h @@ -132,6 +132,7 @@ extern u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt); extern void clockevents_register_device(struct clock_event_device *dev); +extern void clockevents_config(struct clock_event_device *dev, u32 freq); extern void clockevents_config_and_register(struct clock_event_device *dev, u32 freq, unsigned long min_delta, unsigned long max_delta); diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 9cd928f7a7c6..7e1ce012a851 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -297,8 +297,7 @@ void clockevents_register_device(struct clock_event_device *dev) } EXPORT_SYMBOL_GPL(clockevents_register_device); -static void clockevents_config(struct clock_event_device *dev, - u32 freq) +void clockevents_config(struct clock_event_device *dev, u32 freq) { u64 sec; diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 6a3a5b9ff561..efd386667536 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -814,6 +814,16 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) return HRTIMER_RESTART; } +static int sched_skew_tick; + +static int __init skew_tick(char *str) +{ + get_option(&str, &sched_skew_tick); + + return 0; +} +early_param("skew_tick", skew_tick); + /** * tick_setup_sched_timer - setup the tick emulation timer */ @@ -831,6 +841,14 @@ void tick_setup_sched_timer(void) /* Get the next period (per cpu) */ hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); + /* Offset the tick to avert xtime_lock contention. */ + if (sched_skew_tick) { + u64 offset = ktime_to_ns(tick_period) >> 1; + do_div(offset, num_possible_cpus()); + offset *= smp_processor_id(); + hrtimer_add_expires_ns(&ts->sched_timer, offset); + } + for (;;) { hrtimer_forward(&ts->sched_timer, now, tick_period); hrtimer_start_expires(&ts->sched_timer, |