--- /dev/null
+/*
+ * Copyright (C) 2013-2014 Altera Corporation
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/delay.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+#define ALTERA_TIMER_STATUS_REG 0
+#define ALTERA_TIMER_CONTROL_REG 4
+#define ALTERA_TIMER_PERIODL_REG 8
+#define ALTERA_TIMER_PERIODH_REG 12
+#define ALTERA_TIMER_SNAPL_REG 16
+#define ALTERA_TIMER_SNAPH_REG 20
+
+#define ALTERA_TIMER_CONTROL_ITO_MSK (0x1)
+#define ALTERA_TIMER_CONTROL_CONT_MSK (0x2)
+#define ALTERA_TIMER_CONTROL_START_MSK (0x4)
+#define ALTERA_TIMER_CONTROL_STOP_MSK (0x8)
+
+struct nios2_timer {
+ void __iomem *base;
+ unsigned long freq;
+ int irq;
+};
+
+struct nios2_clockevent_dev {
+ struct nios2_timer timer;
+ struct clock_event_device ced;
+};
+
+struct nios2_clocksource {
+ struct nios2_timer timer;
+ struct clocksource cs;
+};
+
+static inline struct nios2_clockevent_dev *
+ to_nios2_clkevent(struct clock_event_device *evt)
+{
+ return container_of(evt, struct nios2_clockevent_dev, ced);
+}
+
+static inline struct nios2_clocksource *
+ to_nios2_clksource(struct clocksource *cs)
+{
+ return container_of(cs, struct nios2_clocksource, cs);
+}
+
+static u16 timer_readw(struct nios2_timer *timer, u32 offs)
+{
+ return readw(timer->base + offs);
+}
+
+static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
+{
+ writew(val, timer->base + offs);
+}
+
+static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
+{
+ unsigned long count;
+
+ timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
+ count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
+ timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
+
+ return count;
+}
+
+static cycle_t nios2_timer_read(struct clocksource *cs)
+{
+ struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
+ unsigned long flags;
+ u32 count;
+
+ local_irq_save(flags);
+ count = read_timersnapshot(&nios2_cs->timer);
+ local_irq_restore(flags);
+
+ /* Counter is counting down */
+ return ~count;
+}
+
+static struct nios2_clocksource nios2_cs = {
+ .cs = {
+ .name = "nios2-clksrc",
+ .rating = 250,
+ .read = nios2_timer_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ },
+};
+
+cycles_t get_cycles(void)
+{
+ return nios2_timer_read(&nios2_cs.cs);
+}
+
+static void nios2_timer_start(struct nios2_timer *timer)
+{
+ u16 ctrl;
+
+ ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
+ ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
+ timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
+}
+
+static void nios2_timer_stop(struct nios2_timer *timer)
+{
+ u16 ctrl;
+
+ ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
+ ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
+ timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
+}
+
+static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
+ enum clock_event_mode mode)
+{
+ u16 ctrl;
+
+ /* The timer's actual period is one cycle greater than the value
+ * stored in the period register. */
+ period--;
+
+ ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
+ /* stop counter */
+ timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
+ ALTERA_TIMER_CONTROL_REG);
+
+ /* write new count */
+ timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
+ timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
+
+ ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
+ if (mode == CLOCK_EVT_MODE_PERIODIC)
+ ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
+ else
+ ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
+ timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
+}
+
+static int nios2_timer_set_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
+
+ nios2_timer_config(&nios2_ced->timer, delta, evt->mode);
+
+ return 0;
+}
+
+static void nios2_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ unsigned long period;
+ struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
+ struct nios2_timer *timer = &nios2_ced->timer;
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ period = DIV_ROUND_UP(timer->freq, HZ);
+ nios2_timer_config(timer, period, CLOCK_EVT_MODE_PERIODIC);
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ nios2_timer_stop(timer);
+ break;
+ case CLOCK_EVT_MODE_RESUME:
+ nios2_timer_start(timer);
+ break;
+ }
+}
+
+irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = (struct clock_event_device *) dev_id;
+ struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
+
+ /* Clear the interrupt condition */
+ timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static void __init nios2_timer_get_base_and_freq(struct device_node *np,
+ void __iomem **base, u32 *freq)
+{
+ *base = of_iomap(np, 0);
+ if (!*base)
+ panic("Unable to map reg for %s\n", np->name);
+
+ if (of_property_read_u32(np, "clock-frequency", freq))
+ panic("Unable to get %s clock frequency\n", np->name);
+}
+
+static struct nios2_clockevent_dev nios2_ce = {
+ .ced = {
+ .name = "nios2-clkevent",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .rating = 250,
+ .shift = 32,
+ .set_next_event = nios2_timer_set_next_event,
+ .set_mode = nios2_timer_set_mode,
+ },
+};
+
+static __init void nios2_clockevent_init(struct device_node *timer)
+{
+ void __iomem *iobase;
+ u32 freq;
+ int irq;
+
+ nios2_timer_get_base_and_freq(timer, &iobase, &freq);
+
+ irq = irq_of_parse_and_map(timer, 0);
+ if (irq < 0)
+ panic("Unable to parse timer irq\n");
+
+ nios2_ce.timer.base = iobase;
+ nios2_ce.timer.irq = irq;
+ nios2_ce.timer.freq = freq;
+
+ nios2_ce.ced.cpumask = cpumask_of(0);
+ nios2_ce.ced.irq = irq;
+
+ nios2_timer_stop(&nios2_ce.timer);
+ /* clear pending interrupt */
+ timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
+
+ if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
+ &nios2_ce.ced))
+ panic("Unable to setup timer irq\n");
+
+ clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
+}
+
+static __init void nios2_clocksource_init(struct device_node *timer)
+{
+ unsigned int ctrl;
+ void __iomem *iobase;
+ u32 freq;
+
+ nios2_timer_get_base_and_freq(timer, &iobase, &freq);
+
+ nios2_cs.timer.base = iobase;
+ nios2_cs.timer.freq = freq;
+
+ clocksource_register_hz(&nios2_cs.cs, freq);
+
+ timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
+ timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
+
+ /* interrupt disable + continuous + start */
+ ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
+ timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
+
+ /* Calibrate the delay loop directly */
+ lpj_fine = freq / HZ;
+}
+
+/*
+ * The first timer instance will use as a clockevent. If there are two or
+ * more instances, the second one gets used as clocksource and all
+ * others are unused.
+*/
+static void __init nios2_time_init(struct device_node *timer)
+{
+ static int num_called;
+
+ switch (num_called) {
+ case 0:
+ nios2_clockevent_init(timer);
+ break;
+ case 1:
+ nios2_clocksource_init(timer);
+ break;
+ default:
+ break;
+ }
+
+ num_called++;
+}
+
+void read_persistent_clock(struct timespec *ts)
+{
+ ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
+ ts->tv_nsec = 0;
+}
+
+void __init time_init(void)
+{
+ clocksource_of_init();
+}
+
+CLOCKSOURCE_OF_DECLARE(nios2_timer, "altr,timer-1.0", nios2_time_init);
projects / kernel.git / commitdiff