diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/clocksource/Kconfig | 3 | ||||
| -rw-r--r-- | drivers/clocksource/Makefile | 1 | ||||
| -rw-r--r-- | drivers/clocksource/dw_apb_timer.c | 401 |
3 files changed, 405 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index d8d3e02b912..34e9c4f8892 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -12,3 +12,6 @@ config CLKBLD_I8253 config CLKSRC_MMIO bool + +config DW_APB_TIMER + bool diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index 7922a0cfc99..85ad1646a7b 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -8,3 +8,4 @@ obj-$(CONFIG_SH_TIMER_MTU2) += sh_mtu2.o obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.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/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c new file mode 100644 index 00000000000..580f870541a --- /dev/null +++ b/drivers/clocksource/dw_apb_timer.c @@ -0,0 +1,401 @@ +/* + * (C) Copyright 2009 Intel Corporation + * Author: Jacob Pan (jacob.jun.pan@intel.com) + * + * Shared with ARM platforms, Jamie Iles, Picochip 2011 + * + * 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. + * + * Support for the Synopsys DesignWare APB Timers. + */ +#include <linux/dw_apb_timer.h> +#include <linux/delay.h> +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/io.h> +#include <linux/slab.h> + +#define APBT_MIN_PERIOD 4 +#define APBT_MIN_DELTA_USEC 200 + +#define APBTMR_N_LOAD_COUNT 0x00 +#define APBTMR_N_CURRENT_VALUE 0x04 +#define APBTMR_N_CONTROL 0x08 +#define APBTMR_N_EOI 0x0c +#define APBTMR_N_INT_STATUS 0x10 + +#define APBTMRS_INT_STATUS 0xa0 +#define APBTMRS_EOI 0xa4 +#define APBTMRS_RAW_INT_STATUS 0xa8 +#define APBTMRS_COMP_VERSION 0xac + +#define APBTMR_CONTROL_ENABLE (1 << 0) +/* 1: periodic, 0:free running. */ +#define APBTMR_CONTROL_MODE_PERIODIC (1 << 1) +#define APBTMR_CONTROL_INT (1 << 2) + +static inline struct dw_apb_clock_event_device * +ced_to_dw_apb_ced(struct clock_event_device *evt) +{ + return container_of(evt, struct dw_apb_clock_event_device, ced); +} + +static inline struct dw_apb_clocksource * +clocksource_to_dw_apb_clocksource(struct clocksource *cs) +{ + return container_of(cs, struct dw_apb_clocksource, cs); +} + +static unsigned long apbt_readl(struct dw_apb_timer *timer, unsigned long offs) +{ + return readl(timer->base + offs); +} + +static void apbt_writel(struct dw_apb_timer *timer, unsigned long val, + unsigned long offs) +{ + writel(val, timer->base + offs); +} + +static void apbt_disable_int(struct dw_apb_timer *timer) +{ + unsigned long ctrl = apbt_readl(timer, APBTMR_N_CONTROL); + + ctrl |= APBTMR_CONTROL_INT; + apbt_writel(timer, ctrl, APBTMR_N_CONTROL); +} + +/** + * dw_apb_clockevent_pause() - stop the clock_event_device from running + * + * @dw_ced: The APB clock to stop generating events. + */ +void dw_apb_clockevent_pause(struct dw_apb_clock_event_device *dw_ced) +{ + disable_irq(dw_ced->timer.irq); + apbt_disable_int(&dw_ced->timer); +} + +static void apbt_eoi(struct dw_apb_timer *timer) +{ + apbt_readl(timer, APBTMR_N_EOI); +} + +static irqreturn_t dw_apb_clockevent_irq(int irq, void *data) +{ + struct clock_event_device *evt = data; + struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt); + + if (!evt->event_handler) { + pr_info("Spurious APBT timer interrupt %d", irq); + return IRQ_NONE; + } + + if (dw_ced->eoi) + dw_ced->eoi(&dw_ced->timer); + + evt->event_handler(evt); + return IRQ_HANDLED; +} + +static void apbt_enable_int(struct dw_apb_timer *timer) +{ + unsigned long ctrl = apbt_readl(timer, APBTMR_N_CONTROL); + /* clear pending intr */ + apbt_readl(timer, APBTMR_N_EOI); + ctrl &= ~APBTMR_CONTROL_INT; + apbt_writel(timer, ctrl, APBTMR_N_CONTROL); +} + +static void apbt_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + unsigned long ctrl; + unsigned long period; + struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt); + + pr_debug("%s CPU %d mode=%d\n", __func__, first_cpu(*evt->cpumask), + mode); + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + period = DIV_ROUND_UP(dw_ced->timer.freq, HZ); + ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL); + ctrl |= APBTMR_CONTROL_MODE_PERIODIC; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + /* + * DW APB p. 46, have to disable timer before load counter, + * may cause sync problem. + */ + ctrl &= ~APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + udelay(1); + pr_debug("Setting clock period %lu for HZ %d\n", period, HZ); + apbt_writel(&dw_ced->timer, period, APBTMR_N_LOAD_COUNT); + ctrl |= APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + break; + + case CLOCK_EVT_MODE_ONESHOT: + ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL); + /* + * set free running mode, this mode will let timer reload max + * timeout which will give time (3min on 25MHz clock) to rearm + * the next event, therefore emulate the one-shot mode. + */ + ctrl &= ~APBTMR_CONTROL_ENABLE; + ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC; + + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + /* write again to set free running mode */ + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + + /* + * DW APB p. 46, load counter with all 1s before starting free + * running mode. + */ + apbt_writel(&dw_ced->timer, ~0, APBTMR_N_LOAD_COUNT); + ctrl &= ~APBTMR_CONTROL_INT; + ctrl |= APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + break; + + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL); + ctrl &= ~APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + break; + + case CLOCK_EVT_MODE_RESUME: + apbt_enable_int(&dw_ced->timer); + break; + } +} + +static int apbt_next_event(unsigned long delta, + struct clock_event_device *evt) +{ + unsigned long ctrl; + struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt); + + /* Disable timer */ + ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL); + ctrl &= ~APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + /* write new count */ + apbt_writel(&dw_ced->timer, delta, APBTMR_N_LOAD_COUNT); + ctrl |= APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + + return 0; +} + +/** + * dw_apb_clockevent_init() - use an APB timer as a clock_event_device + * + * @cpu: The CPU the events will be targeted at. + * @name: The name used for the timer and the IRQ for it. + * @rating: The rating to give the timer. + * @base: I/O base for the timer registers. + * @irq: The interrupt number to use for the timer. + * @freq: The frequency that the timer counts at. + * + * This creates a clock_event_device for using with the generic clock layer + * but does not start and register it. This should be done with + * dw_apb_clockevent_register() as the next step. If this is the first time + * it has been called for a timer then the IRQ will be requested, if not it + * just be enabled to allow CPU hotplug to avoid repeatedly requesting and + * releasing the IRQ. + */ +struct dw_apb_clock_event_device * +dw_apb_clockevent_init(int cpu, const char *name, unsigned rating, + void __iomem *base, int irq, unsigned long freq) +{ + struct dw_apb_clock_event_device *dw_ced = + kzalloc(sizeof(*dw_ced), GFP_KERNEL); + int err; + + if (!dw_ced) + return NULL; + + dw_ced->timer.base = base; + dw_ced->timer.irq = irq; + dw_ced->timer.freq = freq; + + clockevents_calc_mult_shift(&dw_ced->ced, freq, APBT_MIN_PERIOD); + dw_ced->ced.max_delta_ns = clockevent_delta2ns(0x7fffffff, + &dw_ced->ced); + dw_ced->ced.min_delta_ns = clockevent_delta2ns(5000, &dw_ced->ced); + dw_ced->ced.cpumask = cpumask_of(cpu); + dw_ced->ced.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; + dw_ced->ced.set_mode = apbt_set_mode; + dw_ced->ced.set_next_event = apbt_next_event; + dw_ced->ced.irq = dw_ced->timer.irq; + dw_ced->ced.rating = rating; + dw_ced->ced.name = name; + + dw_ced->irqaction.name = dw_ced->ced.name; + dw_ced->irqaction.handler = dw_apb_clockevent_irq; + dw_ced->irqaction.dev_id = &dw_ced->ced; + dw_ced->irqaction.irq = irq; + dw_ced->irqaction.flags = IRQF_TIMER | IRQF_IRQPOLL | + IRQF_NOBALANCING | + IRQF_DISABLED; + + dw_ced->eoi = apbt_eoi; + err = setup_irq(irq, &dw_ced->irqaction); + if (err) { + pr_err("failed to request timer irq\n"); + kfree(dw_ced); + dw_ced = NULL; + } + + return dw_ced; +} + +/** + * dw_apb_clockevent_resume() - resume a clock that has been paused. + * + * @dw_ced: The APB clock to resume. + */ +void dw_apb_clockevent_resume(struct dw_apb_clock_event_device *dw_ced) +{ + enable_irq(dw_ced->timer.irq); +} + +/** + * dw_apb_clockevent_stop() - stop the clock_event_device and release the IRQ. + * + * @dw_ced: The APB clock to stop generating the events. + */ +void dw_apb_clockevent_stop(struct dw_apb_clock_event_device *dw_ced) +{ + free_irq(dw_ced->timer.irq, &dw_ced->ced); +} + +/** + * dw_apb_clockevent_register() - register the clock with the generic layer + * + * @dw_ced: The APB clock to register as a clock_event_device. + */ +void dw_apb_clockevent_register(struct dw_apb_clock_event_device *dw_ced) +{ + apbt_writel(&dw_ced->timer, 0, APBTMR_N_CONTROL); + clockevents_register_device(&dw_ced->ced); + apbt_enable_int(&dw_ced->timer); +} + +/** + * dw_apb_clocksource_start() - start the clocksource counting. + * + * @dw_cs: The clocksource to start. + * + * This is used to start the clocksource before registration and can be used + * to enable calibration of timers. + */ +void dw_apb_clocksource_start(struct dw_apb_clocksource *dw_cs) +{ + /* + * start count down from 0xffff_ffff. this is done by toggling the + * enable bit then load initial load count to ~0. + */ + unsigned long ctrl = apbt_readl(&dw_cs->timer, APBTMR_N_CONTROL); + + ctrl &= ~APBTMR_CONTROL_ENABLE; + apbt_writel(&dw_cs->timer, ctrl, APBTMR_N_CONTROL); + apbt_writel(&dw_cs->timer, ~0, APBTMR_N_LOAD_COUNT); + /* enable, mask interrupt */ + ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC; + ctrl |= (APBTMR_CONTROL_ENABLE | APBTMR_CONTROL_INT); + apbt_writel(&dw_cs->timer, ctrl, APBTMR_N_CONTROL); + /* read it once to get cached counter value initialized */ + dw_apb_clocksource_read(dw_cs); +} + +static cycle_t __apbt_read_clocksource(struct clocksource *cs) +{ + unsigned long current_count; + struct dw_apb_clocksource *dw_cs = + clocksource_to_dw_apb_clocksource(cs); + + current_count = apbt_readl(&dw_cs->timer, APBTMR_N_CURRENT_VALUE); + + return (cycle_t)~current_count; +} + +static void apbt_restart_clocksource(struct clocksource *cs) +{ + struct dw_apb_clocksource *dw_cs = + clocksource_to_dw_apb_clocksource(cs); + + dw_apb_clocksource_start(dw_cs); +} + +/** + * dw_apb_clocksource_init() - use an APB timer as a clocksource. + * + * @rating: The rating to give the clocksource. + * @name: The name for the clocksource. + * @base: The I/O base for the timer registers. + * @freq: The frequency that the timer counts at. + * + * This creates a clocksource using an APB timer but does not yet register it + * with the clocksource system. This should be done with + * dw_apb_clocksource_register() as the next step. + */ +struct dw_apb_clocksource * +dw_apb_clocksource_init(unsigned rating, char *name, void __iomem *base, + unsigned long freq) +{ + struct dw_apb_clocksource *dw_cs = kzalloc(sizeof(*dw_cs), GFP_KERNEL); + + if (!dw_cs) + return NULL; + + dw_cs->timer.base = base; + dw_cs->timer.freq = freq; + dw_cs->cs.name = name; + dw_cs->cs.rating = rating; + dw_cs->cs.read = __apbt_read_clocksource; + dw_cs->cs.mask = CLOCKSOURCE_MASK(32); + dw_cs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS; + dw_cs->cs.resume = apbt_restart_clocksource; + + return dw_cs; +} + +/** + * dw_apb_clocksource_register() - register the APB clocksource. + * + * @dw_cs: The clocksource to register. + */ +void dw_apb_clocksource_register(struct dw_apb_clocksource *dw_cs) +{ + clocksource_register_hz(&dw_cs->cs, dw_cs->timer.freq); +} + +/** + * dw_apb_clocksource_read() - read the current value of a clocksource. + * + * @dw_cs: The clocksource to read. + */ +cycle_t dw_apb_clocksource_read(struct dw_apb_clocksource *dw_cs) +{ + return (cycle_t)~apbt_readl(&dw_cs->timer, APBTMR_N_CURRENT_VALUE); +} + +/** + * dw_apb_clocksource_unregister() - unregister and free a clocksource. + * + * @dw_cs: The clocksource to unregister/free. + */ +void dw_apb_clocksource_unregister(struct dw_apb_clocksource *dw_cs) +{ + clocksource_unregister(&dw_cs->cs); + + kfree(dw_cs); +} |