1 files changed, 292 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-nxp-pit.c b/drivers/clocksource/timer-nxp-pit.c
new file mode 100644
index 000000000000..2a0ee4109ead
--- /dev/null
+++ b/drivers/clocksource/timer-nxp-pit.c
@@ -0,0 +1,292 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2012-2013 Freescale Semiconductor, Inc.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+#include <linux/clk.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+
+/*
+ * Each pit takes 0x10 Bytes register space
+ */
+#define PIT0_OFFSET	0x100
+#define PIT_CH(n)       (PIT0_OFFSET + 0x10 * (n))
+
+#define PITMCR(__base)	(__base)
+
+#define PITMCR_FRZ	BIT(0)
+#define PITMCR_MDIS	BIT(1)
+
+#define PITLDVAL(__base)	(__base)
+#define PITTCTRL(__base)	((__base) + 0x08)
+
+#define PITCVAL_OFFSET	0x04
+#define PITCVAL(__base)	((__base) + 0x04)
+
+#define PITTCTRL_TEN			BIT(0)
+#define PITTCTRL_TIE			BIT(1)
+
+#define PITTFLG(__base)	((__base) + 0x0c)
+
+#define PITTFLG_TIF			BIT(0)
+
+struct pit_timer {
+	void __iomem *clksrc_base;
+	void __iomem *clkevt_base;
+	unsigned long cycle_per_jiffy;
+	struct clock_event_device ced;
+	struct clocksource cs;
+};
+
+static void __iomem *sched_clock_base;
+
+static inline struct pit_timer *ced_to_pit(struct clock_event_device *ced)
+{
+	return container_of(ced, struct pit_timer, ced);
+}
+
+static inline struct pit_timer *cs_to_pit(struct clocksource *cs)
+{
+	return container_of(cs, struct pit_timer, cs);
+}
+
+static inline void pit_module_enable(void __iomem *base)
+{
+	writel(0, PITMCR(base));
+}
+
+static inline void pit_module_disable(void __iomem *base)
+{
+	writel(PITMCR_MDIS, PITMCR(base));
+}
+
+static inline void pit_timer_enable(void __iomem *base, bool tie)
+{
+	u32 val = PITTCTRL_TEN | (tie ? PITTCTRL_TIE : 0);
+
+	writel(val, PITTCTRL(base));
+}
+
+static inline void pit_timer_disable(void __iomem *base)
+{
+	writel(0, PITTCTRL(base));
+}
+
+static inline void pit_timer_set_counter(void __iomem *base, unsigned int cnt)
+{
+	writel(cnt, PITLDVAL(base));
+}
+
+static inline void pit_timer_irqack(struct pit_timer *pit)
+{
+	writel(PITTFLG_TIF, PITTFLG(pit->clkevt_base));
+}
+
+static u64 notrace pit_read_sched_clock(void)
+{
+	return ~readl(sched_clock_base);
+}
+
+static u64 pit_timer_clocksource_read(struct clocksource *cs)
+{
+	struct pit_timer *pit = cs_to_pit(cs);
+
+	return (u64)~readl(PITCVAL(pit->clksrc_base));
+}
+
+static int __init pit_clocksource_init(struct pit_timer *pit, const char *name,
+				       void __iomem *base, unsigned long rate)
+{
+	/*
+	 * The channels 0 and 1 can be chained to build a 64-bit
+	 * timer. Let's use the channel 2 as a clocksource and leave
+	 * the channels 0 and 1 unused for anyone else who needs them
+	 */
+	pit->clksrc_base = base + PIT_CH(2);
+	pit->cs.name = name;
+	pit->cs.rating = 300;
+	pit->cs.read = pit_timer_clocksource_read;
+	pit->cs.mask = CLOCKSOURCE_MASK(32);
+	pit->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+	/* set the max load value and start the clock source counter */
+	pit_timer_disable(pit->clksrc_base);
+	pit_timer_set_counter(pit->clksrc_base, ~0);
+	pit_timer_enable(pit->clksrc_base, 0);
+
+	sched_clock_base = pit->clksrc_base + PITCVAL_OFFSET;
+	sched_clock_register(pit_read_sched_clock, 32, rate);
+
+	return clocksource_register_hz(&pit->cs, rate);
+}
+
+static int pit_set_next_event(unsigned long delta, struct clock_event_device *ced)
+{
+	struct pit_timer *pit = ced_to_pit(ced);
+
+	/*
+	 * set a new value to PITLDVAL register will not restart the timer,
+	 * to abort the current cycle and start a timer period with the new
+	 * value, the timer must be disabled and enabled again.
+	 * and the PITLAVAL should be set to delta minus one according to pit
+	 * hardware requirement.
+	 */
+	pit_timer_disable(pit->clkevt_base);
+	pit_timer_set_counter(pit->clkevt_base, delta - 1);
+	pit_timer_enable(pit->clkevt_base, true);
+
+	return 0;
+}
+
+static int pit_shutdown(struct clock_event_device *ced)
+{
+	struct pit_timer *pit = ced_to_pit(ced);
+
+	pit_timer_disable(pit->clkevt_base);
+
+	return 0;
+}
+
+static int pit_set_periodic(struct clock_event_device *ced)
+{
+	struct pit_timer *pit = ced_to_pit(ced);
+
+	pit_set_next_event(pit->cycle_per_jiffy, ced);
+
+	return 0;
+}
+
+static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *ced = dev_id;
+	struct pit_timer *pit = ced_to_pit(ced);
+
+	pit_timer_irqack(pit);
+
+	/*
+	 * pit hardware doesn't support oneshot, it will generate an interrupt
+	 * and reload the counter value from PITLDVAL when PITCVAL reach zero,
+	 * and start the counter again. So software need to disable the timer
+	 * to stop the counter loop in ONESHOT mode.
+	 */
+	if (likely(clockevent_state_oneshot(ced)))
+		pit_timer_disable(pit->clkevt_base);
+
+	ced->event_handler(ced);
+
+	return IRQ_HANDLED;
+}
+
+static int __init pit_clockevent_init(struct pit_timer *pit, const char *name,
+				      void __iomem *base, unsigned long rate,
+				      int irq, unsigned int cpu)
+{
+	/*
+	 * The channels 0 and 1 can be chained to build a 64-bit
+	 * timer. Let's use the channel 3 as a clockevent and leave
+	 * the channels 0 and 1 unused for anyone else who needs them
+	 */
+	pit->clkevt_base = base + PIT_CH(3);
+	pit->cycle_per_jiffy = rate / (HZ);
+
+	pit_timer_disable(pit->clkevt_base);
+
+	pit_timer_irqack(pit);
+
+	BUG_ON(request_irq(irq, pit_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
+			   name, &pit->ced));
+
+	pit->ced.cpumask = cpumask_of(cpu);
+	pit->ced.irq = irq;
+
+	pit->ced.name = name;
+	pit->ced.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	pit->ced.set_state_shutdown = pit_shutdown;
+	pit->ced.set_state_periodic = pit_set_periodic;
+	pit->ced.set_next_event	= pit_set_next_event;
+	pit->ced.rating	= 300;
+
+	/*
+	 * The value for the LDVAL register trigger is calculated as:
+	 * LDVAL trigger = (period / clock period) - 1
+	 * The pit is a 32-bit down count timer, when the counter value
+	 * reaches 0, it will generate an interrupt, thus the minimal
+	 * LDVAL trigger value is 1. And then the min_delta is
+	 * minimal LDVAL trigger value + 1, and the max_delta is full 32-bit.
+	 */
+	clockevents_config_and_register(&pit->ced, rate, 2, 0xffffffff);
+
+	return 0;
+}
+
+static int __init pit_timer_init(struct device_node *np)
+{
+	struct pit_timer *pit;
+	struct clk *pit_clk;
+	void __iomem *timer_base;
+	const char *name = of_node_full_name(np);
+	unsigned long clk_rate;
+	int irq, ret;
+
+	pit = kzalloc(sizeof(*pit), GFP_KERNEL);
+	if (!pit)
+		return -ENOMEM;
+
+	ret = -ENXIO;
+	timer_base = of_iomap(np, 0);
+	if (!timer_base) {
+		pr_err("Failed to iomap\n");
+		goto out_kfree;
+	}
+
+	ret = -EINVAL;
+	irq = irq_of_parse_and_map(np, 0);
+	if (irq <= 0) {
+		pr_err("Failed to irq_of_parse_and_map\n");
+		goto out_iounmap;
+	}
+
+	pit_clk = of_clk_get(np, 0);
+	if (IS_ERR(pit_clk)) {
+		ret = PTR_ERR(pit_clk);
+		goto out_iounmap;
+	}
+
+	ret = clk_prepare_enable(pit_clk);
+	if (ret)
+		goto out_clk_put;
+
+	clk_rate = clk_get_rate(pit_clk);
+
+	/* enable the pit module */
+	pit_module_enable(timer_base);
+
+	ret = pit_clocksource_init(pit, name, timer_base, clk_rate);
+	if (ret)
+		goto out_pit_module_disable;
+
+	ret = pit_clockevent_init(pit, name, timer_base, clk_rate, irq, 0);
+	if (ret)
+		goto out_pit_clocksource_unregister;
+
+	return 0;
+
+out_pit_clocksource_unregister:
+	clocksource_unregister(&pit->cs);
+out_pit_module_disable:
+	pit_module_disable(timer_base);
+	clk_disable_unprepare(pit_clk);
+out_clk_put:
+	clk_put(pit_clk);
+out_iounmap:
+	iounmap(timer_base);
+out_kfree:
+	kfree(pit);
+
+	return ret;
+}
+TIMER_OF_DECLARE(vf610, "fsl,vf610-pit", pit_timer_init);