[OpenWrt-Devel] [PATCH 2/7] ramips: improve systick timer

[Michael Lee]

From: michael lee <igvtee at gmail.com>

when sleep mode is disable use MIPS as clocksource and clockevent instead of systick.
because MIPS timer has higher resolution 5ns less than systick 20us and
larger counter bits 32 > 16.
clean interrupt by write compare register at isr.
fix typo cause sleep mode not enable.

Signed-off-by: Michael Lee <igvtee at gmail.com>
---
 target/linux/ramips/patches-3.18/0066-cevt.patch | 151 ++++++++++++++++++++++-
 1 file changed, 145 insertions(+), 6 deletions(-)

diff --git a/target/linux/ramips/patches-3.18/0066-cevt.patch b/target/linux/ramips/patches-3.18/0066-cevt.patch
index 192afe4..01cb588 100644
--- a/target/linux/ramips/patches-3.18/0066-cevt.patch
+++ b/target/linux/ramips/patches-3.18/0066-cevt.patch
@@ -1,12 +1,151 @@
 --- a/arch/mips/ralink/cevt-rt3352.c
 +++ b/arch/mips/ralink/cevt-rt3352.c
-@@ -53,8 +53,7 @@ static int systick_next_event(unsigned l
- 
+@@ -45,18 +45,33 @@ static void (*systick_freq_scaling)(stru
+ static void systick_set_clock_mode(enum clock_event_mode mode,
+ 				struct clock_event_device *evt);
+
++static inline unsigned int read_count(struct systick_device *sdev)
++{
++	return ioread32(sdev->membase + SYSTICK_COUNT);
++}
++
++static inline unsigned int read_compare(struct systick_device *sdev)
++{
++	return ioread32(sdev->membase + SYSTICK_COMPARE);
++}
++
++static inline void write_compare(struct systick_device *sdev, unsigned int val)
++{
++	iowrite32(val, sdev->membase + SYSTICK_COMPARE);
++}
++
+ static int systick_next_event(unsigned long delta,
+ 				struct clock_event_device *evt)
+ {
+ 	struct systick_device *sdev;
+-	u32 count;
++	int res;
+
  	sdev = container_of(evt, struct systick_device, dev);
- 	count = ioread32(sdev->membase + SYSTICK_COUNT);
+-	count = ioread32(sdev->membase + SYSTICK_COUNT);
 -	count = (count + delta) % SYSTICK_FREQ;
 -	iowrite32(count, sdev->membase + SYSTICK_COMPARE);
-+	iowrite32(count + delta, sdev->membase + SYSTICK_COMPARE);
- 
- 	return 0;
++	delta += read_count(sdev);
++	write_compare(sdev, delta);
++	res = ((int)(read_count(sdev) - delta) >= 0) ? -ETIME : 0;
+
+-	return 0;
++	return res;
+ }
+
+ static void systick_event_handler(struct clock_event_device *dev)
+@@ -66,20 +81,25 @@ static void systick_event_handler(struct
+
+ static irqreturn_t systick_interrupt(int irq, void *dev_id)
+ {
+-	struct clock_event_device *dev = (struct clock_event_device *) dev_id;
++	int ret = 0;
++	struct clock_event_device *cdev;
++	struct systick_device *sdev;
+
+-	dev->event_handler(dev);
++	if (read_c0_cause() & STATUSF_IP7) {
++		cdev = (struct clock_event_device *) dev_id;
++		sdev = container_of(cdev, struct systick_device, dev);
++
++		/* Clear Count/Compare Interrupt */
++		write_compare(sdev, read_compare(sdev));
++		cdev->event_handler(cdev);
++		ret = 1;
++	}
+
+-	return IRQ_HANDLED;
++	return IRQ_RETVAL(ret);
+ }
+
+ static struct systick_device systick = {
+ 	.dev = {
+-		/*
+-		 * cevt-r4k uses 300, make sure systick
+-		 * gets used if available
+-		 */
+-		.rating		= 310,
+ 		.features	= CLOCK_EVT_FEAT_ONESHOT,
+ 		.set_next_event	= systick_next_event,
+ 		.set_mode	= systick_set_clock_mode,
+@@ -126,13 +146,14 @@ static void systick_set_clock_mode(enum
+ 			systick_freq_scaling(sdev, 1);
+ 		break;
+
++	case CLOCK_EVT_MODE_UNUSED:
+ 	case CLOCK_EVT_MODE_SHUTDOWN:
+ 		if (systick_freq_scaling)
+ 			systick_freq_scaling(sdev, 0);
+ 		if (sdev->irq_requested)
+-			free_irq(systick.dev.irq, &systick_irqaction);
++			remove_irq(systick.dev.irq, &systick_irqaction);
+ 		sdev->irq_requested = 0;
+-		iowrite32(0, systick.membase + SYSTICK_CONFIG);
++		iowrite32(CFG_CNT_EN, systick.membase + SYSTICK_CONFIG);
+ 		break;
+
+ 	default:
+@@ -142,38 +163,45 @@ static void systick_set_clock_mode(enum
+ }
+
+ static const struct of_device_id systick_match[] = {
+-	{ .compatible = "ralink,mt7620-systick", .data = mt7620_freq_scaling},
++	{ .compatible = "ralink,mt7620a-systick", .data = mt7620_freq_scaling},
+ 	{},
+ };
+
+ static void __init ralink_systick_init(struct device_node *np)
+ {
+ 	const struct of_device_id *match;
++	int rating = 200;
+
+ 	systick.membase = of_iomap(np, 0);
+ 	if (!systick.membase)
+ 		return;
+
+ 	match = of_match_node(systick_match, np);
+-	if (match)
++	if (match) {
+ 		systick_freq_scaling = match->data;
++		/*
++		 * cevt-r4k uses 300, make sure systick
++		 * gets used if available
++		 */
++		rating = 310;
++	}
+
+-	systick_irqaction.name = np->name;
+-	systick.dev.name = np->name;
+-	clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
+-	systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
+-	systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
++	/* enable counter than register clock source */
++	iowrite32(CFG_CNT_EN, systick.membase + SYSTICK_CONFIG);
++	clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
++			SYSTICK_FREQ, rating, 16, clocksource_mmio_readl_up);
++
++	/* register clock event */
+ 	systick.dev.irq = irq_of_parse_and_map(np, 0);
+ 	if (!systick.dev.irq) {
+ 		pr_err("%s: request_irq failed", np->name);
+ 		return;
+ 	}
+-
+-	clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
+-			SYSTICK_FREQ, 301, 16, clocksource_mmio_readl_up);
+-
+-	clockevents_register_device(&systick.dev);
+-
++	systick_irqaction.name = np->name;
++	systick.dev.name = np->name;
++	systick.dev.rating = rating;
++	systick.dev.cpumask = cpumask_of(0);
++	clockevents_config_and_register(&systick.dev, SYSTICK_FREQ, 0x3, 0x7fff);
+ 	pr_info("%s: running - mult: %d, shift: %d\n",
+ 			np->name, systick.dev.mult, systick.dev.shift);
  }
-- 
2.3.6
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