1 files changed, 340 insertions, 0 deletions
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
new file mode 100644
index 0000000000..9a14f721a2
--- /dev/null
+++ b/arch/arm/kernel/smp_twd.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/kernel/smp_twd.c
+ *
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/smp.h>
+#include <linux/jiffies.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+
+#include <asm/smp_twd.h>
+
+/* set up by the platform code */
+static void __iomem *twd_base;
+
+static struct clk *twd_clk;
+static unsigned long twd_timer_rate;
+static DEFINE_PER_CPU(bool, percpu_setup_called);
+
+static struct clock_event_device __percpu *twd_evt;
+static unsigned int twd_features =
+		CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+static int twd_ppi;
+
+static int twd_shutdown(struct clock_event_device *clk)
+{
+	writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
+	return 0;
+}
+
+static int twd_set_oneshot(struct clock_event_device *clk)
+{
+	/* period set, and timer enabled in 'next_event' hook */
+	writel_relaxed(TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT,
+		       twd_base + TWD_TIMER_CONTROL);
+	return 0;
+}
+
+static int twd_set_periodic(struct clock_event_device *clk)
+{
+	unsigned long ctrl = TWD_TIMER_CONTROL_ENABLE |
+			     TWD_TIMER_CONTROL_IT_ENABLE |
+			     TWD_TIMER_CONTROL_PERIODIC;
+
+	writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
+		       twd_base + TWD_TIMER_LOAD);
+	writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
+	return 0;
+}
+
+static int twd_set_next_event(unsigned long evt,
+			struct clock_event_device *unused)
+{
+	unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL);
+
+	ctrl |= TWD_TIMER_CONTROL_ENABLE;
+
+	writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER);
+	writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
+
+	return 0;
+}
+
+/*
+ * local_timer_ack: checks for a local timer interrupt.
+ *
+ * If a local timer interrupt has occurred, acknowledge and return 1.
+ * Otherwise, return 0.
+ */
+static int twd_timer_ack(void)
+{
+	if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) {
+		writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT);
+		return 1;
+	}
+
+	return 0;
+}
+
+static void twd_timer_stop(void)
+{
+	struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
+
+	twd_shutdown(clk);
+	disable_percpu_irq(clk->irq);
+}
+
+/*
+ * Updates clockevent frequency when the cpu frequency changes.
+ * Called on the cpu that is changing frequency with interrupts disabled.
+ */
+static void twd_update_frequency(void *new_rate)
+{
+	twd_timer_rate = *((unsigned long *) new_rate);
+
+	clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate);
+}
+
+static int twd_rate_change(struct notifier_block *nb,
+	unsigned long flags, void *data)
+{
+	struct clk_notifier_data *cnd = data;
+
+	/*
+	 * The twd clock events must be reprogrammed to account for the new
+	 * frequency.  The timer is local to a cpu, so cross-call to the
+	 * changing cpu.
+	 */
+	if (flags == POST_RATE_CHANGE)
+		on_each_cpu(twd_update_frequency,
+				  (void *)&cnd->new_rate, 1);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block twd_clk_nb = {
+	.notifier_call = twd_rate_change,
+};
+
+static int twd_clk_init(void)
+{
+	if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
+		return clk_notifier_register(twd_clk, &twd_clk_nb);
+
+	return 0;
+}
+core_initcall(twd_clk_init);
+
+static void twd_calibrate_rate(void)
+{
+	unsigned long count;
+	u64 waitjiffies;
+
+	/*
+	 * If this is the first time round, we need to work out how fast
+	 * the timer ticks
+	 */
+	if (twd_timer_rate == 0) {
+		pr_info("Calibrating local timer... ");
+
+		/* Wait for a tick to start */
+		waitjiffies = get_jiffies_64() + 1;
+
+		while (get_jiffies_64() < waitjiffies)
+			udelay(10);
+
+		/* OK, now the tick has started, let's get the timer going */
+		waitjiffies += 5;
+
+				 /* enable, no interrupt or reload */
+		writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL);
+
+				 /* maximum value */
+		writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
+
+		while (get_jiffies_64() < waitjiffies)
+			udelay(10);
+
+		count = readl_relaxed(twd_base + TWD_TIMER_COUNTER);
+
+		twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
+
+		pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
+			(twd_timer_rate / 10000) % 100);
+	}
+}
+
+static irqreturn_t twd_handler(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+
+	if (twd_timer_ack()) {
+		evt->event_handler(evt);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static void twd_get_clock(struct device_node *np)
+{
+	int err;
+
+	if (np)
+		twd_clk = of_clk_get(np, 0);
+	else
+		twd_clk = clk_get_sys("smp_twd", NULL);
+
+	if (IS_ERR(twd_clk)) {
+		pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
+		return;
+	}
+
+	err = clk_prepare_enable(twd_clk);
+	if (err) {
+		pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
+		clk_put(twd_clk);
+		return;
+	}
+
+	twd_timer_rate = clk_get_rate(twd_clk);
+}
+
+/*
+ * Setup the local clock events for a CPU.
+ */
+static void twd_timer_setup(void)
+{
+	struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
+	int cpu = smp_processor_id();
+
+	/*
+	 * If the basic setup for this CPU has been done before don't
+	 * bother with the below.
+	 */
+	if (per_cpu(percpu_setup_called, cpu)) {
+		writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
+		clockevents_register_device(clk);
+		enable_percpu_irq(clk->irq, 0);
+		return;
+	}
+	per_cpu(percpu_setup_called, cpu) = true;
+
+	twd_calibrate_rate();
+
+	/*
+	 * The following is done once per CPU the first time .setup() is
+	 * called.
+	 */
+	writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
+
+	clk->name = "local_timer";
+	clk->features = twd_features;
+	clk->rating = 350;
+	clk->set_state_shutdown = twd_shutdown;
+	clk->set_state_periodic = twd_set_periodic;
+	clk->set_state_oneshot = twd_set_oneshot;
+	clk->tick_resume = twd_shutdown;
+	clk->set_next_event = twd_set_next_event;
+	clk->irq = twd_ppi;
+	clk->cpumask = cpumask_of(cpu);
+
+	clockevents_config_and_register(clk, twd_timer_rate,
+					0xf, 0xffffffff);
+	enable_percpu_irq(clk->irq, 0);
+}
+
+static int twd_timer_starting_cpu(unsigned int cpu)
+{
+	twd_timer_setup();
+	return 0;
+}
+
+static int twd_timer_dying_cpu(unsigned int cpu)
+{
+	twd_timer_stop();
+	return 0;
+}
+
+static int __init twd_local_timer_common_register(struct device_node *np)
+{
+	int err;
+
+	twd_evt = alloc_percpu(struct clock_event_device);
+	if (!twd_evt) {
+		err = -ENOMEM;
+		goto out_free;
+	}
+
+	err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
+	if (err) {
+		pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
+		goto out_free;
+	}
+
+	cpuhp_setup_state_nocalls(CPUHP_AP_ARM_TWD_STARTING,
+				  "arm/timer/twd:starting",
+				  twd_timer_starting_cpu, twd_timer_dying_cpu);
+
+	twd_get_clock(np);
+	if (!of_property_read_bool(np, "always-on"))
+		twd_features |= CLOCK_EVT_FEAT_C3STOP;
+
+	/*
+	 * Immediately configure the timer on the boot CPU, unless we need
+	 * jiffies to be incrementing to calibrate the rate in which case
+	 * setup the timer in late_time_init.
+	 */
+	if (twd_timer_rate)
+		twd_timer_setup();
+	else
+		late_time_init = twd_timer_setup;
+
+	return 0;
+
+out_free:
+	iounmap(twd_base);
+	twd_base = NULL;
+	free_percpu(twd_evt);
+
+	return err;
+}
+
+static int __init twd_local_timer_of_register(struct device_node *np)
+{
+	int err;
+
+	twd_ppi = irq_of_parse_and_map(np, 0);
+	if (!twd_ppi) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	twd_base = of_iomap(np, 0);
+	if (!twd_base) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = twd_local_timer_common_register(np);
+
+out:
+	WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
+	return err;
+}
+TIMER_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
+TIMER_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
+TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);