--- /dev/null
+/*
+ * Copyright 2012-2013 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+#include <linux/clk.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <asm/sched_clock.h>
+
+/*
+ * Each pit takes 0x10 Bytes register space
+ */
+#define PITMCR 0x00
+#define PIT0_OFFSET 0x100
+#define PITn_OFFSET(n) (PIT0_OFFSET + 0x10 * (n))
+#define PITLDVAL 0x00
+#define PITCVAL 0x04
+#define PITTCTRL 0x08
+#define PITTFLG 0x0c
+
+#define PITMCR_MDIS (0x1 << 1)
+
+#define PITTCTRL_TEN (0x1 << 0)
+#define PITTCTRL_TIE (0x1 << 1)
+#define PITCTRL_CHN (0x1 << 2)
+
+#define PITTFLG_TIF 0x1
+
+static void __iomem *clksrc_base;
+static void __iomem *clkevt_base;
+static unsigned long cycle_per_jiffy;
+
+static inline void pit_timer_enable(void)
+{
+ __raw_writel(PITTCTRL_TEN | PITTCTRL_TIE, clkevt_base + PITTCTRL);
+}
+
+static inline void pit_timer_disable(void)
+{
+ __raw_writel(0, clkevt_base + PITTCTRL);
+}
+
+static inline void pit_irq_acknowledge(void)
+{
+ __raw_writel(PITTFLG_TIF, clkevt_base + PITTFLG);
+}
+
+static unsigned int pit_read_sched_clock(void)
+{
+ return __raw_readl(clksrc_base + PITCVAL);
+}
+
+static int __init pit_clocksource_init(unsigned long rate)
+{
+ /* set the max load value and start the clock source counter */
+ __raw_writel(0, clksrc_base + PITTCTRL);
+ __raw_writel(~0UL, clksrc_base + PITLDVAL);
+ __raw_writel(PITTCTRL_TEN, clksrc_base + PITTCTRL);
+
+ setup_sched_clock(pit_read_sched_clock, 32, rate);
+ return clocksource_mmio_init(clksrc_base + PITCVAL, "vf-pit", rate,
+ 300, 32, clocksource_mmio_readl_down);
+}
+
+static int pit_set_next_event(unsigned long delta,
+ struct clock_event_device *unused)
+{
+ /*
+ * 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();
+ __raw_writel(delta - 1, clkevt_base + PITLDVAL);
+ pit_timer_enable();
+
+ return 0;
+}
+
+static void pit_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ pit_set_next_event(cycle_per_jiffy, evt);
+ break;
+ default:
+ break;
+ }
+}
+
+static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+
+ pit_irq_acknowledge();
+
+ /*
+ * 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(evt->mode == CLOCK_EVT_MODE_ONESHOT))
+ pit_timer_disable();
+
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static struct clock_event_device clockevent_pit = {
+ .name = "VF pit timer",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .set_mode = pit_set_mode,
+ .set_next_event = pit_set_next_event,
+ .rating = 300,
+};
+
+static struct irqaction pit_timer_irq = {
+ .name = "VF pit timer",
+ .flags = IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = pit_timer_interrupt,
+ .dev_id = &clockevent_pit,
+};
+
+static int __init pit_clockevent_init(unsigned long rate, int irq)
+{
+ __raw_writel(0, clkevt_base + PITTCTRL);
+ __raw_writel(PITTFLG_TIF, clkevt_base + PITTFLG);
+
+ BUG_ON(setup_irq(irq, &pit_timer_irq));
+
+ clockevent_pit.cpumask = cpumask_of(0);
+ clockevent_pit.irq = irq;
+ /*
+ * 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 conter 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(&clockevent_pit, rate, 2, 0xffffffff);
+
+ return 0;
+}
+
+static void __init pit_timer_init(struct device_node *np)
+{
+ struct clk *pit_clk;
+ void __iomem *timer_base;
+ unsigned long clk_rate;
+ int irq;
+
+ timer_base = of_iomap(np, 0);
+ BUG_ON(!timer_base);
+
+ /*
+ * PIT0 and PIT1 can be chained to build a 64-bit timer,
+ * so choose PIT2 as clocksource, PIT3 as clockevent device,
+ * and leave PIT0 and PIT1 unused for anyone else who needs them.
+ */
+ clksrc_base = timer_base + PITn_OFFSET(2);
+ clkevt_base = timer_base + PITn_OFFSET(3);
+
+ irq = irq_of_parse_and_map(np, 0);
+ BUG_ON(irq <= 0);
+
+ pit_clk = of_clk_get(np, 0);
+ BUG_ON(IS_ERR(pit_clk));
+
+ BUG_ON(clk_prepare_enable(pit_clk));
+
+ clk_rate = clk_get_rate(pit_clk);
+ cycle_per_jiffy = clk_rate / (HZ);
+
+ /* enable the pit module */
+ __raw_writel(~PITMCR_MDIS, timer_base + PITMCR);
+
+ BUG_ON(pit_clocksource_init(clk_rate));
+
+ pit_clockevent_init(clk_rate, irq);
+}
+CLOCKSOURCE_OF_DECLARE(vf610, "fsl,vf610-pit", pit_timer_init);
projects / firefly-linux-kernel-4.4.55.git / commitdiff