Merge tag 'timers-v5.14' of https://git.linaro.org/people/daniel.lezc…

…ano/linux into timers/core

Pull clockevent/source updates from Daniel Lezcano:

 - Remove arch_timer_rate1 variable as it is unused in the architected
   ARM timer (Jisheng Zhang)

 - Minor cleanups (whitespace, constification, ...) for the Samsung pwm
   timer (Krzysztof Kozlowski)

 - Acknowledge and disable the timer interrupt at suspend time to
   prevent the suspend to be aborted by the ATF if there is a pending
   one on the Mediatek timer (Evan Benn)

 - Save and restore the configuration register at suspend/resume time
   for TI dm timer (Tony Lindgren)

 - Set the scene for the next timers support by renaming the array
   variables on the Ingenic time (Zhou Yanjie)

 - Add the clock rate change notification to adjust the prescalar value
   and compensate the clock source on the ARM global timer (Andrea
   Merello)

 - Add missing variable static annotation on the ARM global timer (Zou
   Wei)

 - Remove a duplicate argument when building the bits field on the ARM
   global timer (Wan Jiabing)

 - Improve the timer workaround function by reducing the loop on the
   Allwinner A64 timer (Samuel Holland)

 - Do no restore the register context in case of error on the TI dm
   timer (Tony Lindgren)

Link: https://lore.kernel.org/r/65ed5f60-d7a5-b4ae-ff78-0382d4671cc5@linaro.org

arch/arm/mach-zynq/Kconfig

@@ -6,7 +6,7 @@ config ARCH_ZYNQ
 	select ARCH_SUPPORTS_BIG_ENDIAN
 	select ARM_AMBA
 	select ARM_GIC
-	select ARM_GLOBAL_TIMER if !CPU_FREQ
+	select ARM_GLOBAL_TIMER
 	select CADENCE_TTC_TIMER
 	select HAVE_ARM_SCU if SMP
 	select HAVE_ARM_TWD if SMP

drivers/clocksource/Kconfig

@@ -358,6 +358,20 @@ config ARM_GLOBAL_TIMER
 	help
 	  This option enables support for the ARM global timer unit.
 
+config ARM_GT_INITIAL_PRESCALER_VAL
+	int "ARM global timer initial prescaler value"
+	default 2 if ARCH_ZYNQ
+	default 1
+	depends on ARM_GLOBAL_TIMER
+	help
+	  When the ARM global timer initializes, its current rate is declared
+	  to the kernel and maintained forever. Should it's parent clock
+	  change, the driver tries to fix the timer's internal prescaler.
+	  On some machs (i.e. Zynq) the initial prescaler value thus poses
+	  bounds about how much the parent clock is allowed to decrease or
+	  increase wrt the initial clock value.
+	  This affects CPU_FREQ max delta from the initial frequency.
+
 config ARM_TIMER_SP804
 	bool "Support for Dual Timer SP804 module" if COMPILE_TEST
 	depends on GENERIC_SCHED_CLOCK && CLKDEV_LOOKUP

drivers/clocksource/arm_arch_timer.c

@@ -64,7 +64,6 @@ struct arch_timer {
 #define to_arch_timer(e) container_of(e, struct arch_timer, evt)
 
 static u32 arch_timer_rate __ro_after_init;
-u32 arch_timer_rate1 __ro_after_init;
 static int arch_timer_ppi[ARCH_TIMER_MAX_TIMER_PPI] __ro_after_init;
 
 static const char *arch_timer_ppi_names[ARCH_TIMER_MAX_TIMER_PPI] = {
@@ -365,7 +364,7 @@ static u64 notrace arm64_858921_read_cntvct_el0(void)
 	do {								\
 		_val = read_sysreg(reg);				\
 		_retries--;						\
-	} while (((_val + 1) & GENMASK(9, 0)) <= 1 && _retries);	\
+	} while (((_val + 1) & GENMASK(8, 0)) <= 1 && _retries);	\
 									\
 	WARN_ON_ONCE(!_retries);					\
 	_val;								\

drivers/clocksource/arm_global_timer.c

@@ -31,6 +31,10 @@
 #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_SHIFT      8
+#define GT_CONTROL_PRESCALER_MAX        0xF
+#define GT_CONTROL_PRESCALER_MASK       (GT_CONTROL_PRESCALER_MAX << \
+					 GT_CONTROL_PRESCALER_SHIFT)
 
 #define GT_INT_STATUS	0x0c
 #define GT_INT_STATUS_EVENT_FLAG	BIT(0)
@@ -39,14 +43,16 @@
 #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.
  *
  * Note: it is assumed we are using a prescaler value of zero, so this is
  * 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, gt_target_rate;
 static int gt_ppi;
 static struct clock_event_device __percpu *gt_evt;
 
@@ -96,7 +102,10 @@ static void gt_compare_set(unsigned long delta, int periodic)
 	unsigned long ctrl;
 
 	counter += delta;
-	ctrl = GT_CONTROL_TIMER_ENABLE;
+	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);
@@ -123,7 +132,7 @@ static int gt_clockevent_shutdown(struct clock_event_device *evt)
 
 static int gt_clockevent_set_periodic(struct clock_event_device *evt)
 {
-	gt_compare_set(DIV_ROUND_CLOSEST(gt_clk_rate, HZ), 1);
+	gt_compare_set(DIV_ROUND_CLOSEST(gt_target_rate, HZ), 1);
 	return 0;
 }
 
@@ -177,7 +186,7 @@ static int gt_starting_cpu(unsigned int cpu)
 	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;
@@ -232,9 +241,28 @@ 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 |= psv << GT_CONTROL_PRESCALER_SHIFT;
+	writel(reg, gt_base + GT_CONTROL);
+}
+
+static u32 gt_read_presc(void)
+{
+	u32 reg;
+
+	reg = readl(gt_base + GT_CONTROL);
+	reg &= GT_CONTROL_PRESCALER_MASK;
+	return reg >> GT_CONTROL_PRESCALER_SHIFT;
+}
+
 static void __init gt_delay_timer_init(void)
 {
-	gt_delay_timer.freq = gt_clk_rate;
+	gt_delay_timer.freq = gt_target_rate;
 	register_current_timer_delay(&gt_delay_timer);
 }
 
@@ -243,18 +271,81 @@ static int __init gt_clocksource_init(void)
 	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(((CONFIG_ARM_GT_INITIAL_PRESCALER_VAL - 1) <<
+		GT_CONTROL_PRESCALER_SHIFT)
+	       | GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
 
 #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
-	sched_clock_register(gt_sched_clock_read, 64, gt_clk_rate);
+	sched_clock_register(gt_sched_clock_read, 64, gt_target_rate);
 #endif
-	return clocksource_register_hz(&gt_clocksource, gt_clk_rate);
+	return clocksource_register_hz(&gt_clocksource, gt_target_rate);
+}
+
+static int gt_clk_rate_change_cb(struct notifier_block *nb,
+				 unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+
+	switch (event) {
+	case PRE_RATE_CHANGE:
+	{
+		int psv;
+
+		psv = DIV_ROUND_CLOSEST(ndata->new_rate,
+					gt_target_rate);
+
+		if (abs(gt_target_rate - (ndata->new_rate / psv)) > MAX_F_ERR)
+			return NOTIFY_BAD;
+
+		psv--;
+
+		/* prescaler within legal range? */
+		if (psv < 0 || psv > GT_CONTROL_PRESCALER_MAX)
+			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 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_DONE;
 }
 
 static int __init global_timer_of_register(struct device_node *np)
 {
 	struct clk *gt_clk;
+	static unsigned long gt_clk_rate;
 	int err = 0;
 
 	/*
@@ -292,11 +383,20 @@ static int __init global_timer_of_register(struct device_node *np)
 	}
 
 	gt_clk_rate = clk_get_rate(gt_clk);
+	gt_target_rate = gt_clk_rate / CONFIG_ARM_GT_INITIAL_PRESCALER_VAL;
+	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,
@@ -326,6 +426,8 @@ static int __init global_timer_of_register(struct device_node *np)
 	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:

drivers/clocksource/ingenic-sysost.c

@@ -186,7 +186,7 @@ static const struct clk_ops ingenic_ost_global_timer_ops = {
 
 static const char * const ingenic_ost_clk_parents[] = { "ext" };
 
-static const struct ingenic_ost_clk_info ingenic_ost_clk_info[] = {
+static const struct ingenic_ost_clk_info x1000_ost_clk_info[] = {
 	[OST_CLK_PERCPU_TIMER] = {
 		.init_data = {
 			.name = "percpu timer",
@@ -414,14 +414,14 @@ static const struct ingenic_soc_info x1000_soc_info = {
 	.num_channels = 2,
 };
 
-static const struct of_device_id __maybe_unused ingenic_ost_of_match[] __initconst = {
-	{ .compatible = "ingenic,x1000-ost", .data = &x1000_soc_info, },
+static const struct of_device_id __maybe_unused ingenic_ost_of_matches[] __initconst = {
+	{ .compatible = "ingenic,x1000-ost", .data = &x1000_soc_info },
 	{ /* sentinel */ }
 };
 
 static int __init ingenic_ost_probe(struct device_node *np)
 {
-	const struct of_device_id *id = of_match_node(ingenic_ost_of_match, np);
+	const struct of_device_id *id = of_match_node(ingenic_ost_of_matches, np);
 	struct ingenic_ost *ost;
 	unsigned int i;
 	int ret;
@@ -462,7 +462,7 @@ static int __init ingenic_ost_probe(struct device_node *np)
 	ost->clocks->num = ost->soc_info->num_channels;
 
 	for (i = 0; i < ost->clocks->num; i++) {
-		ret = ingenic_ost_register_clock(ost, i, &ingenic_ost_clk_info[i], ost->clocks);
+		ret = ingenic_ost_register_clock(ost, i, &x1000_ost_clk_info[i], ost->clocks);
 		if (ret) {
 			pr_crit("%s: Cannot register clock %d\n", __func__, i);
 			goto err_unregister_ost_clocks;