/* * (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, const 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); }