--- /dev/null
+/*
+ * (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__,
+ cpumask_first(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;
+
+ 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);
+}
Code Review / kvmfornfv.git / blobdiff