--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Clocksource driver for Loongson-1 SoC
+ *
+ * Copyright (c) 2023 Keguang Zhang <keguang.zhang@gmail.com>
+ */
+
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/sizes.h>
+#include "timer-of.h"
+
+/* Loongson-1 PWM Timer Register Definitions */
+#define PWM_CNTR 0x0
+#define PWM_HRC 0x4
+#define PWM_LRC 0x8
+#define PWM_CTRL 0xc
+
+/* PWM Control Register Bits */
+#define INT_LRC_EN BIT(11)
+#define INT_HRC_EN BIT(10)
+#define CNTR_RST BIT(7)
+#define INT_SR BIT(6)
+#define INT_EN BIT(5)
+#define PWM_SINGLE BIT(4)
+#define PWM_OE BIT(3)
+#define CNT_EN BIT(0)
+
+#define CNTR_WIDTH 24
+
+DEFINE_RAW_SPINLOCK(ls1x_timer_lock);
+
+struct ls1x_clocksource {
+ void __iomem *reg_base;
+ unsigned long ticks_per_jiffy;
+ struct clocksource clksrc;
+};
+
+static inline struct ls1x_clocksource *to_ls1x_clksrc(struct clocksource *c)
+{
+ return container_of(c, struct ls1x_clocksource, clksrc);
+}
+
+static inline void ls1x_pwmtimer_set_period(unsigned int period,
+ struct timer_of *to)
+{
+ writel(period, timer_of_base(to) + PWM_LRC);
+ writel(period, timer_of_base(to) + PWM_HRC);
+}
+
+static inline void ls1x_pwmtimer_clear(struct timer_of *to)
+{
+ writel(0, timer_of_base(to) + PWM_CNTR);
+}
+
+static inline void ls1x_pwmtimer_start(struct timer_of *to)
+{
+ writel((INT_EN | PWM_OE | CNT_EN), timer_of_base(to) + PWM_CTRL);
+}
+
+static inline void ls1x_pwmtimer_stop(struct timer_of *to)
+{
+ writel(0, timer_of_base(to) + PWM_CTRL);
+}
+
+static inline void ls1x_pwmtimer_irq_ack(struct timer_of *to)
+{
+ int val;
+
+ val = readl(timer_of_base(to) + PWM_CTRL);
+ val |= INT_SR;
+ writel(val, timer_of_base(to) + PWM_CTRL);
+}
+
+static irqreturn_t ls1x_clockevent_isr(int irq, void *dev_id)
+{
+ struct clock_event_device *clkevt = dev_id;
+ struct timer_of *to = to_timer_of(clkevt);
+
+ ls1x_pwmtimer_irq_ack(to);
+ ls1x_pwmtimer_clear(to);
+ ls1x_pwmtimer_start(to);
+
+ clkevt->event_handler(clkevt);
+
+ return IRQ_HANDLED;
+}
+
+static int ls1x_clockevent_set_state_periodic(struct clock_event_device *clkevt)
+{
+ struct timer_of *to = to_timer_of(clkevt);
+
+ raw_spin_lock(&ls1x_timer_lock);
+ ls1x_pwmtimer_set_period(timer_of_period(to), to);
+ ls1x_pwmtimer_clear(to);
+ ls1x_pwmtimer_start(to);
+ raw_spin_unlock(&ls1x_timer_lock);
+
+ return 0;
+}
+
+static int ls1x_clockevent_tick_resume(struct clock_event_device *clkevt)
+{
+ raw_spin_lock(&ls1x_timer_lock);
+ ls1x_pwmtimer_start(to_timer_of(clkevt));
+ raw_spin_unlock(&ls1x_timer_lock);
+
+ return 0;
+}
+
+static int ls1x_clockevent_set_state_shutdown(struct clock_event_device *clkevt)
+{
+ raw_spin_lock(&ls1x_timer_lock);
+ ls1x_pwmtimer_stop(to_timer_of(clkevt));
+ raw_spin_unlock(&ls1x_timer_lock);
+
+ return 0;
+}
+
+static int ls1x_clockevent_set_next(unsigned long evt,
+ struct clock_event_device *clkevt)
+{
+ struct timer_of *to = to_timer_of(clkevt);
+
+ raw_spin_lock(&ls1x_timer_lock);
+ ls1x_pwmtimer_set_period(evt, to);
+ ls1x_pwmtimer_clear(to);
+ ls1x_pwmtimer_start(to);
+ raw_spin_unlock(&ls1x_timer_lock);
+
+ return 0;
+}
+
+static struct timer_of ls1x_to = {
+ .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
+ .clkevt = {
+ .name = "ls1x-pwmtimer",
+ .features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT,
+ .rating = 300,
+ .set_next_event = ls1x_clockevent_set_next,
+ .set_state_periodic = ls1x_clockevent_set_state_periodic,
+ .set_state_oneshot = ls1x_clockevent_set_state_shutdown,
+ .set_state_shutdown = ls1x_clockevent_set_state_shutdown,
+ .tick_resume = ls1x_clockevent_tick_resume,
+ },
+ .of_irq = {
+ .handler = ls1x_clockevent_isr,
+ .flags = IRQF_TIMER,
+ },
+};
+
+/*
+ * Since the PWM timer overflows every two ticks, its not very useful
+ * to just read by itself. So use jiffies to emulate a free
+ * running counter:
+ */
+static u64 ls1x_clocksource_read(struct clocksource *cs)
+{
+ struct ls1x_clocksource *ls1x_cs = to_ls1x_clksrc(cs);
+ unsigned long flags;
+ int count;
+ u32 jifs;
+ static int old_count;
+ static u32 old_jifs;
+
+ raw_spin_lock_irqsave(&ls1x_timer_lock, flags);
+ /*
+ * Although our caller may have the read side of xtime_lock,
+ * this is now a seqlock, and we are cheating in this routine
+ * by having side effects on state that we cannot undo if
+ * there is a collision on the seqlock and our caller has to
+ * retry. (Namely, old_jifs and old_count.) So we must treat
+ * jiffies as volatile despite the lock. We read jiffies
+ * before latching the timer count to guarantee that although
+ * the jiffies value might be older than the count (that is,
+ * the counter may underflow between the last point where
+ * jiffies was incremented and the point where we latch the
+ * count), it cannot be newer.
+ */
+ jifs = jiffies;
+ /* read the count */
+ count = readl(ls1x_cs->reg_base + PWM_CNTR);
+
+ /*
+ * It's possible for count to appear to go the wrong way for this
+ * reason:
+ *
+ * The timer counter underflows, but we haven't handled the resulting
+ * interrupt and incremented jiffies yet.
+ *
+ * Previous attempts to handle these cases intelligently were buggy, so
+ * we just do the simple thing now.
+ */
+ if (count < old_count && jifs == old_jifs)
+ count = old_count;
+
+ old_count = count;
+ old_jifs = jifs;
+
+ raw_spin_unlock_irqrestore(&ls1x_timer_lock, flags);
+
+ return (u64)(jifs * ls1x_cs->ticks_per_jiffy) + count;
+}
+
+static struct ls1x_clocksource ls1x_clocksource = {
+ .clksrc = {
+ .name = "ls1x-pwmtimer",
+ .rating = 300,
+ .read = ls1x_clocksource_read,
+ .mask = CLOCKSOURCE_MASK(CNTR_WIDTH),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ },
+};
+
+static int __init ls1x_pwm_clocksource_init(struct device_node *np)
+{
+ struct timer_of *to = &ls1x_to;
+ int ret;
+
+ ret = timer_of_init(np, to);
+ if (ret)
+ return ret;
+
+ clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
+ 0x1, GENMASK(CNTR_WIDTH - 1, 0));
+
+ ls1x_clocksource.reg_base = timer_of_base(to);
+ ls1x_clocksource.ticks_per_jiffy = timer_of_period(to);
+
+ return clocksource_register_hz(&ls1x_clocksource.clksrc,
+ timer_of_rate(to));
+}
+
+TIMER_OF_DECLARE(ls1x_pwm_clocksource, "loongson,ls1b-pwmtimer",
+ ls1x_pwm_clocksource_init);
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