--- /dev/null
+/*
+ * Copyright (C) 2015 ARM Limited
+ *
+ * Author: Vladimir Murzin <vladimir.murzin@arm.com>
+ *
+ * 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.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+#define TIMER_CTRL 0x0
+#define TIMER_CTRL_ENABLE BIT(0)
+#define TIMER_CTRL_IE BIT(3)
+
+#define TIMER_VALUE 0x4
+#define TIMER_RELOAD 0x8
+#define TIMER_INT 0xc
+
+struct clockevent_mps2 {
+ void __iomem *reg;
+ u32 clock_count_per_tick;
+ struct clock_event_device clkevt;
+};
+
+static void __iomem *sched_clock_base;
+
+static u64 notrace mps2_sched_read(void)
+{
+ return ~readl_relaxed(sched_clock_base + TIMER_VALUE);
+}
+
+static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)
+{
+ return container_of(c, struct clockevent_mps2, clkevt);
+}
+
+static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)
+{
+ writel_relaxed(val, to_mps2_clkevt(c)->reg + offset);
+}
+
+static int mps2_timer_shutdown(struct clock_event_device *ce)
+{
+ clockevent_mps2_writel(0, ce, TIMER_RELOAD);
+ clockevent_mps2_writel(0, ce, TIMER_CTRL);
+
+ return 0;
+}
+
+static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)
+{
+ clockevent_mps2_writel(next, ce, TIMER_VALUE);
+ clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
+
+ return 0;
+}
+
+static int mps2_timer_set_periodic(struct clock_event_device *ce)
+{
+ u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;
+
+ clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);
+ clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);
+ clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
+
+ return 0;
+}
+
+static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
+{
+ struct clockevent_mps2 *ce = dev_id;
+ u32 status = readl_relaxed(ce->reg + TIMER_INT);
+
+ if (!status) {
+ pr_warn("spurious interrupt\n");
+ return IRQ_NONE;
+ }
+
+ writel_relaxed(1, ce->reg + TIMER_INT);
+
+ ce->clkevt.event_handler(&ce->clkevt);
+
+ return IRQ_HANDLED;
+}
+
+static int __init mps2_clockevent_init(struct device_node *np)
+{
+ void __iomem *base;
+ struct clk *clk = NULL;
+ struct clockevent_mps2 *ce;
+ u32 rate;
+ int irq, ret;
+ const char *name = "mps2-clkevt";
+
+ ret = of_property_read_u32(np, "clock-frequency", &rate);
+ if (ret) {
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ ret = PTR_ERR(clk);
+ pr_err("failed to get clock for clockevent: %d\n", ret);
+ goto out;
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ pr_err("failed to enable clock for clockevent: %d\n", ret);
+ goto out_clk_put;
+ }
+
+ rate = clk_get_rate(clk);
+ }
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ ret = -EADDRNOTAVAIL;
+ pr_err("failed to map register for clockevent: %d\n", ret);
+ goto out_clk_disable;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (!irq) {
+ ret = -ENOENT;
+ pr_err("failed to get irq for clockevent: %d\n", ret);
+ goto out_iounmap;
+ }
+
+ ce = kzalloc(sizeof(*ce), GFP_KERNEL);
+ if (!ce) {
+ ret = -ENOMEM;
+ goto out_iounmap;
+ }
+
+ ce->reg = base;
+ ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);
+ ce->clkevt.irq = irq;
+ ce->clkevt.name = name;
+ ce->clkevt.rating = 200;
+ ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+ ce->clkevt.cpumask = cpu_possible_mask;
+ ce->clkevt.set_state_shutdown = mps2_timer_shutdown,
+ ce->clkevt.set_state_periodic = mps2_timer_set_periodic,
+ ce->clkevt.set_state_oneshot = mps2_timer_shutdown,
+ ce->clkevt.set_next_event = mps2_timer_set_next_event;
+
+ /* Ensure timer is disabled */
+ writel_relaxed(0, base + TIMER_CTRL);
+
+ ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce);
+ if (ret) {
+ pr_err("failed to request irq for clockevent: %d\n", ret);
+ goto out_kfree;
+ }
+
+ clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);
+
+ return 0;
+
+out_kfree:
+ kfree(ce);
+out_iounmap:
+ iounmap(base);
+out_clk_disable:
+ /* clk_{disable, unprepare, put}() can handle NULL as a parameter */
+ clk_disable_unprepare(clk);
+out_clk_put:
+ clk_put(clk);
+out:
+ return ret;
+}
+
+static int __init mps2_clocksource_init(struct device_node *np)
+{
+ void __iomem *base;
+ struct clk *clk = NULL;
+ u32 rate;
+ int ret;
+ const char *name = "mps2-clksrc";
+
+ ret = of_property_read_u32(np, "clock-frequency", &rate);
+ if (ret) {
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ ret = PTR_ERR(clk);
+ pr_err("failed to get clock for clocksource: %d\n", ret);
+ goto out;
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ pr_err("failed to enable clock for clocksource: %d\n", ret);
+ goto out_clk_put;
+ }
+
+ rate = clk_get_rate(clk);
+ }
+
+ base = of_iomap(np, 0);
+ if (!base) {
+ ret = -EADDRNOTAVAIL;
+ pr_err("failed to map register for clocksource: %d\n", ret);
+ goto out_clk_disable;
+ }
+
+ /* Ensure timer is disabled */
+ writel_relaxed(0, base + TIMER_CTRL);
+
+ /* ... and set it up as free-running clocksource */
+ writel_relaxed(0xffffffff, base + TIMER_VALUE);
+ writel_relaxed(0xffffffff, base + TIMER_RELOAD);
+
+ writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL);
+
+ ret = clocksource_mmio_init(base + TIMER_VALUE, name,
+ rate, 200, 32,
+ clocksource_mmio_readl_down);
+ if (ret) {
+ pr_err("failed to init clocksource: %d\n", ret);
+ goto out_iounmap;
+ }
+
+ sched_clock_base = base;
+ sched_clock_register(mps2_sched_read, 32, rate);
+
+ return 0;
+
+out_iounmap:
+ iounmap(base);
+out_clk_disable:
+ /* clk_{disable, unprepare, put}() can handle NULL as a parameter */
+ clk_disable_unprepare(clk);
+out_clk_put:
+ clk_put(clk);
+out:
+ return ret;
+}
+
+static void __init mps2_timer_init(struct device_node *np)
+{
+ static int has_clocksource, has_clockevent;
+ int ret;
+
+ if (!has_clocksource) {
+ ret = mps2_clocksource_init(np);
+ if (!ret) {
+ has_clocksource = 1;
+ return;
+ }
+ }
+
+ if (!has_clockevent) {
+ ret = mps2_clockevent_init(np);
+ if (!ret) {
+ has_clockevent = 1;
+ return;
+ }
+ }
+}
+
+CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);
projects / cascardo / linux.git / commitdiff