1 files changed, 224 insertions, 73 deletions

diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
index db8afc7427a6..5e3d6bb7e437 100644
--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c
@@ -1,21 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * drivers/clocksource/arm_global_timer.c
  *
  * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
  * Author: Stuart Menefy <stuart.menefy@st.com>
  * Author: Srinivas Kandagatla <srinivas.kandagatla@st.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.
  */
 
 #include <linux/init.h>
 #include <linux/interrupt.h>
+#include <linux/bitfield.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
 #include <linux/cpu.h>
 #include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/of.h>
@@ -33,6 +32,7 @@
 #define GT_CONTROL_COMP_ENABLE		BIT(1)	/* banked */
 #define GT_CONTROL_IRQ_ENABLE		BIT(2)	/* banked */
 #define GT_CONTROL_AUTO_INC		BIT(3)	/* banked */
+#define GT_CONTROL_PRESCALER_MASK	GENMASK(15, 8)
 
 #define GT_INT_STATUS	0x0c
 #define GT_INT_STATUS_EVENT_FLAG	BIT(0)
@@ -41,6 +41,7 @@
 #define GT_COMP1	0x14
 #define GT_AUTO_INC	0x18
 
+#define MAX_F_ERR 50
 /*
  * We are expecting to be clocked by the ARM peripheral clock.
  *
@@ -48,7 +49,9 @@
  * the units for all operations.
  */
 static void __iomem *gt_base;
-static unsigned long gt_clk_rate;
+static struct notifier_block gt_clk_rate_change_nb;
+static u32 gt_psv_new, gt_psv_bck;
+static unsigned long gt_target_rate;
 static int gt_ppi;
 static struct clock_event_device __percpu *gt_evt;
 
@@ -60,7 +63,7 @@ static struct clock_event_device __percpu *gt_evt;
  *  different to the 32-bit upper value read previously, go back to step 2.
  *  Otherwise the 64-bit timer counter value is correct.
  */
-static u64 gt_counter_read(void)
+static u64 notrace _gt_counter_read(void)
 {
 	u64 counter;
 	u32 lower;
@@ -79,7 +82,12 @@ static u64 gt_counter_read(void)
 	return counter;
 }
 
-/**
+static u64 gt_counter_read(void)
+{
+	return _gt_counter_read();
+}
+
+/*
  * To ensure that updates to comparator value register do not set the
  * Interrupt Status Register proceed as follows:
  * 1. Clear the Comp Enable bit in the Timer Control Register.
@@ -93,40 +101,38 @@ static void gt_compare_set(unsigned long delta, int periodic)
 	unsigned long ctrl;
 
 	counter += delta;
-	ctrl = GT_CONTROL_TIMER_ENABLE;
-	writel(ctrl, gt_base + GT_CONTROL);
-	writel(lower_32_bits(counter), gt_base + GT_COMP0);
-	writel(upper_32_bits(counter), gt_base + GT_COMP1);
+	ctrl = readl(gt_base + GT_CONTROL);
+	ctrl &= ~(GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE |
+		  GT_CONTROL_AUTO_INC);
+	ctrl |= GT_CONTROL_TIMER_ENABLE;
+	writel_relaxed(ctrl, gt_base + GT_CONTROL);
+	writel_relaxed(lower_32_bits(counter), gt_base + GT_COMP0);
+	writel_relaxed(upper_32_bits(counter), gt_base + GT_COMP1);
 
 	if (periodic) {
-		writel(delta, gt_base + GT_AUTO_INC);
+		writel_relaxed(delta, gt_base + GT_AUTO_INC);
 		ctrl |= GT_CONTROL_AUTO_INC;
 	}
 
 	ctrl |= GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE;
-	writel(ctrl, gt_base + GT_CONTROL);
+	writel_relaxed(ctrl, gt_base + GT_CONTROL);
 }
 
-static void gt_clockevent_set_mode(enum clock_event_mode mode,
-				   struct clock_event_device *clk)
+static int gt_clockevent_shutdown(struct clock_event_device *evt)
 {
 	unsigned long ctrl;
 
-	switch (mode) {
-	case CLOCK_EVT_MODE_PERIODIC:
-		gt_compare_set(DIV_ROUND_CLOSEST(gt_clk_rate, HZ), 1);
-		break;
-	case CLOCK_EVT_MODE_ONESHOT:
-	case CLOCK_EVT_MODE_UNUSED:
-	case CLOCK_EVT_MODE_SHUTDOWN:
-		ctrl = readl(gt_base + GT_CONTROL);
-		ctrl &= ~(GT_CONTROL_COMP_ENABLE |
-				GT_CONTROL_IRQ_ENABLE | GT_CONTROL_AUTO_INC);
-		writel(ctrl, gt_base + GT_CONTROL);
-		break;
-	default:
-		break;
-	}
+	ctrl = readl(gt_base + GT_CONTROL);
+	ctrl &= ~(GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE |
+		  GT_CONTROL_AUTO_INC);
+	writel(ctrl, gt_base + GT_CONTROL);
+	return 0;
+}
+
+static int gt_clockevent_set_periodic(struct clock_event_device *evt)
+{
+	gt_compare_set(DIV_ROUND_CLOSEST(gt_target_rate, HZ), 1);
+	return 0;
 }
 
 static int gt_clockevent_set_next_event(unsigned long evt,
@@ -155,7 +161,7 @@ static irqreturn_t gt_clockevent_interrupt(int irq, void *dev_id)
 	 *	the Global Timer flag _after_ having incremented
 	 *	the Comparator register	value to a higher value.
 	 */
-	if (evt->mode == CLOCK_EVT_MODE_ONESHOT)
+	if (clockevent_state_oneshot(evt))
 		gt_compare_set(ULONG_MAX, 0);
 
 	writel_relaxed(GT_INT_STATUS_EVENT_FLAG, gt_base + GT_INT_STATUS);
@@ -164,106 +170,234 @@ static irqreturn_t gt_clockevent_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int __cpuinit gt_clockevents_init(struct clock_event_device *clk)
+static int gt_starting_cpu(unsigned int cpu)
 {
-	int cpu = smp_processor_id();
+	struct clock_event_device *clk = this_cpu_ptr(gt_evt);
 
 	clk->name = "arm_global_timer";
-	clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
-	clk->set_mode = gt_clockevent_set_mode;
+	clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
+		CLOCK_EVT_FEAT_PERCPU;
+	clk->set_state_shutdown = gt_clockevent_shutdown;
+	clk->set_state_periodic = gt_clockevent_set_periodic;
+	clk->set_state_oneshot = gt_clockevent_shutdown;
+	clk->set_state_oneshot_stopped = gt_clockevent_shutdown;
 	clk->set_next_event = gt_clockevent_set_next_event;
 	clk->cpumask = cpumask_of(cpu);
 	clk->rating = 300;
 	clk->irq = gt_ppi;
-	clockevents_config_and_register(clk, gt_clk_rate,
+	clockevents_config_and_register(clk, gt_target_rate,
 					1, 0xffffffff);
 	enable_percpu_irq(clk->irq, IRQ_TYPE_NONE);
 	return 0;
 }
 
-static void gt_clockevents_stop(struct clock_event_device *clk)
+static int gt_dying_cpu(unsigned int cpu)
 {
-	gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
+	struct clock_event_device *clk = this_cpu_ptr(gt_evt);
+
 	disable_percpu_irq(clk->irq);
+	return 0;
 }
 
-static cycle_t gt_clocksource_read(struct clocksource *cs)
+static u64 gt_clocksource_read(struct clocksource *cs)
 {
 	return gt_counter_read();
 }
 
+static void gt_resume(struct clocksource *cs)
+{
+	unsigned long ctrl;
+
+	ctrl = readl(gt_base + GT_CONTROL);
+	if (!(ctrl & GT_CONTROL_TIMER_ENABLE))
+		/* re-enable timer on resume */
+		writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
+}
+
 static struct clocksource gt_clocksource = {
 	.name	= "arm_global_timer",
 	.rating	= 300,
 	.read	= gt_clocksource_read,
 	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+	.resume = gt_resume,
 };
 
 #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
-static u32 notrace gt_sched_clock_read(void)
+static u64 notrace gt_sched_clock_read(void)
 {
-	return gt_counter_read();
+	return _gt_counter_read();
 }
 #endif
 
-static void __init gt_clocksource_init(void)
+static unsigned long gt_read_long(void)
+{
+	return readl_relaxed(gt_base + GT_COUNTER0);
+}
+
+static struct delay_timer gt_delay_timer = {
+	.read_current_timer = gt_read_long,
+};
+
+static void gt_write_presc(u32 psv)
+{
+	u32 reg;
+
+	reg = readl(gt_base + GT_CONTROL);
+	reg &= ~GT_CONTROL_PRESCALER_MASK;
+	reg |= FIELD_PREP(GT_CONTROL_PRESCALER_MASK, psv);
+	writel(reg, gt_base + GT_CONTROL);
+}
+
+static u32 gt_read_presc(void)
+{
+	u32 reg;
+
+	reg = readl(gt_base + GT_CONTROL);
+	return FIELD_GET(GT_CONTROL_PRESCALER_MASK, reg);
+}
+
+static void __init gt_delay_timer_init(void)
+{
+	gt_delay_timer.freq = gt_target_rate;
+	register_current_timer_delay(&gt_delay_timer);
+}
+
+static int __init gt_clocksource_init(unsigned int psv)
 {
 	writel(0, gt_base + GT_CONTROL);
 	writel(0, gt_base + GT_COUNTER0);
 	writel(0, gt_base + GT_COUNTER1);
-	/* enables timer on all the cores */
-	writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
+	/* set prescaler and enable timer on all the cores */
+	writel(FIELD_PREP(GT_CONTROL_PRESCALER_MASK, psv - 1) |
+	       GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
 
 #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
-	setup_sched_clock(gt_sched_clock_read, 32, gt_clk_rate);
+	sched_clock_register(gt_sched_clock_read, 64, gt_target_rate);
 #endif
-	clocksource_register_hz(&gt_clocksource, gt_clk_rate);
+	return clocksource_register_hz(&gt_clocksource, gt_target_rate);
 }
 
-static int __cpuinit gt_cpu_notify(struct notifier_block *self,
-					   unsigned long action, void *hcpu)
+static int gt_clk_rate_change_cb(struct notifier_block *nb,
+				 unsigned long event, void *data)
 {
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_STARTING:
-		gt_clockevents_init(this_cpu_ptr(gt_evt));
+	struct clk_notifier_data *ndata = data;
+
+	switch (event) {
+	case PRE_RATE_CHANGE:
+	{
+		unsigned long psv;
+
+		psv = DIV_ROUND_CLOSEST(ndata->new_rate, gt_target_rate);
+		if (!psv ||
+		    abs(gt_target_rate - (ndata->new_rate / psv)) > MAX_F_ERR)
+			return NOTIFY_BAD;
+
+		psv--;
+
+		/* prescaler within legal range? */
+		if (!FIELD_FIT(GT_CONTROL_PRESCALER_MASK, psv))
+			return NOTIFY_BAD;
+
+		/*
+		 * store timer clock ctrl register so we can restore it in case
+		 * of an abort.
+		 */
+		gt_psv_bck = gt_read_presc();
+		gt_psv_new = psv;
+		/* scale down: adjust divider in post-change notification */
+		if (ndata->new_rate < ndata->old_rate)
+			return NOTIFY_DONE;
+
+		/* scale up: adjust divider now - before frequency change */
+		gt_write_presc(psv);
+		break;
+	}
+	case POST_RATE_CHANGE:
+		/* scale up: pre-change notification did the adjustment */
+		if (ndata->new_rate > ndata->old_rate)
+			return NOTIFY_OK;
+
+		/* scale down: adjust divider now - after frequency change */
+		gt_write_presc(gt_psv_new);
 		break;
-	case CPU_DYING:
-		gt_clockevents_stop(this_cpu_ptr(gt_evt));
+
+	case ABORT_RATE_CHANGE:
+		/* we have to undo the adjustment in case we scale up */
+		if (ndata->new_rate < ndata->old_rate)
+			return NOTIFY_OK;
+
+		/* restore original register value */
+		gt_write_presc(gt_psv_bck);
 		break;
+	default:
+		return NOTIFY_DONE;
 	}
 
-	return NOTIFY_OK;
+	return NOTIFY_DONE;
 }
-static struct notifier_block gt_cpu_nb __cpuinitdata = {
-	.notifier_call = gt_cpu_notify,
+
+struct gt_prescaler_config {
+	const char *compatible;
+	unsigned long prescaler;
+};
+
+static const struct gt_prescaler_config gt_prescaler_configs[] = {
+	/*
+	 * On am43 the global timer clock is a child of the clock used for CPU
+	 * OPPs, so the initial prescaler has to be compatible with all OPPs
+	 * which are 300, 600, 720, 800 and 1000 with a fixed divider of 2, this
+	 * gives us a GCD of 10. Initial frequency is 1000, so the prescaler is
+	 * 50.
+	 */
+	{ .compatible = "ti,am43", .prescaler = 50 },
+	{ .compatible = "xlnx,zynq-7000", .prescaler = 2 },
+	{ .compatible = NULL }
 };
 
-static void __init global_timer_of_register(struct device_node *np)
+static unsigned long gt_get_initial_prescaler_value(struct device_node *np)
+{
+	const struct gt_prescaler_config *config;
+
+	if (CONFIG_ARM_GT_INITIAL_PRESCALER_VAL != 0)
+		return CONFIG_ARM_GT_INITIAL_PRESCALER_VAL;
+
+	for (config = gt_prescaler_configs; config->compatible; config++) {
+		if (of_machine_is_compatible(config->compatible))
+			return config->prescaler;
+	}
+
+	return 1;
+}
+
+static int __init global_timer_of_register(struct device_node *np)
 {
 	struct clk *gt_clk;
-	int err = 0;
+	static unsigned long gt_clk_rate;
+	int err;
+	unsigned long psv;
 
 	/*
-	 * In r2p0 the comparators for each processor with the global timer
+	 * In A9 r2p0 the comparators for each processor with the global timer
 	 * fire when the timer value is greater than or equal to. In previous
 	 * revisions the comparators fired when the timer value was equal to.
 	 */
-	if ((read_cpuid_id() & 0xf0000f) < 0x200000) {
+	if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9
+	    && (read_cpuid_id() & 0xf0000f) < 0x200000) {
 		pr_warn("global-timer: non support for this cpu version.\n");
-		return;
+		return -ENOSYS;
 	}
 
 	gt_ppi = irq_of_parse_and_map(np, 0);
 	if (!gt_ppi) {
 		pr_warn("global-timer: unable to parse irq\n");
-		return;
+		return -EINVAL;
 	}
 
 	gt_base = of_iomap(np, 0);
 	if (!gt_base) {
 		pr_warn("global-timer: invalid base address\n");
-		return;
+		return -ENXIO;
 	}
 
 	gt_clk = of_clk_get(np, 0);
@@ -277,12 +411,22 @@ static void __init global_timer_of_register(struct device_node *np)
 		goto out_unmap;
 	}
 
+	psv = gt_get_initial_prescaler_value(np);
 	gt_clk_rate = clk_get_rate(gt_clk);
+	gt_target_rate = gt_clk_rate / psv;
+	gt_clk_rate_change_nb.notifier_call =
+		gt_clk_rate_change_cb;
+	err = clk_notifier_register(gt_clk, &gt_clk_rate_change_nb);
+	if (err) {
+		pr_warn("Unable to register clock notifier\n");
+		goto out_clk;
+	}
+
 	gt_evt = alloc_percpu(struct clock_event_device);
 	if (!gt_evt) {
 		pr_warn("global-timer: can't allocate memory\n");
 		err = -ENOMEM;
-		goto out_clk;
+		goto out_clk_nb;
 	}
 
 	err = request_percpu_irq(gt_ppi, gt_clockevent_interrupt,
@@ -293,29 +437,36 @@ static void __init global_timer_of_register(struct device_node *np)
 		goto out_free;
 	}
 
-	err = register_cpu_notifier(&gt_cpu_nb);
-	if (err) {
-		pr_warn("global-timer: unable to register cpu notifier.\n");
+	/* Register and immediately configure the timer on the boot CPU */
+	err = gt_clocksource_init(psv);
+	if (err)
 		goto out_irq;
-	}
 
-	/* Immediately configure the timer on the boot CPU */
-	gt_clocksource_init();
-	gt_clockevents_init(this_cpu_ptr(gt_evt));
+	err = cpuhp_setup_state(CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
+				"clockevents/arm/global_timer:starting",
+				gt_starting_cpu, gt_dying_cpu);
+	if (err)
+		goto out_irq;
+
+	gt_delay_timer_init();
 
-	return;
+	return 0;
 
 out_irq:
 	free_percpu_irq(gt_ppi, gt_evt);
 out_free:
 	free_percpu(gt_evt);
+out_clk_nb:
+	clk_notifier_unregister(gt_clk, &gt_clk_rate_change_nb);
 out_clk:
 	clk_disable_unprepare(gt_clk);
 out_unmap:
 	iounmap(gt_base);
 	WARN(err, "ARM Global timer register failed (%d)\n", err);
+
+	return err;
 }
 
 /* Only tested on r2p2 and r3p0  */
-CLOCKSOURCE_OF_DECLARE(arm_gt, "arm,cortex-a9-global-timer",
+TIMER_OF_DECLARE(arm_gt, "arm,cortex-a9-global-timer",
 			global_timer_of_register);