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From e76ecd496c9b074ab21b17f12494d823a407e89a Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Sun, 28 Jul 2013 16:26:41 +0200
Subject: [PATCH 21/57] MIPS: ralink: add cpu frequency scaling
This feature will break udelay() and cause the delay loop to have longer delays
when the frequency is scaled causing a performance hit.
Signed-off-by: John Crispin <blogic@openwrt.org>
---
arch/mips/ralink/cevt-rt3352.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
--- a/arch/mips/ralink/cevt-rt3352.c
+++ b/arch/mips/ralink/cevt-rt3352.c
@@ -29,6 +29,10 @@
/* enable the counter */
#define CFG_CNT_EN 0x1
+/* mt7620 frequency scaling defines */
+#define CLK_LUT_CFG 0x40
+#define SLEEP_EN BIT(31)
+
struct systick_device {
void __iomem *membase;
struct clock_event_device dev;
@@ -36,6 +40,8 @@ struct systick_device {
int freq_scale;
};
+static void (*systick_freq_scaling)(struct systick_device *sdev, int status);
+
static void systick_set_clock_mode(enum clock_event_mode mode,
struct clock_event_device *evt);
@@ -87,6 +93,21 @@ static struct irqaction systick_irqactio
.dev_id = &systick.dev,
};
+static inline void mt7620_freq_scaling(struct systick_device *sdev, int status)
+{
+ if (sdev->freq_scale == status)
+ return;
+
+ sdev->freq_scale = status;
+
+ pr_info("%s: %s autosleep mode\n", systick.dev.name,
+ (status) ? ("enable") : ("disable"));
+ if (status)
+ rt_sysc_w32(rt_sysc_r32(CLK_LUT_CFG) | SLEEP_EN, CLK_LUT_CFG);
+ else
+ rt_sysc_w32(rt_sysc_r32(CLK_LUT_CFG) & ~SLEEP_EN, CLK_LUT_CFG);
+}
+
static void systick_set_clock_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
@@ -101,9 +122,13 @@ static void systick_set_clock_mode(enum
sdev->irq_requested = 1;
iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
systick.membase + SYSTICK_CONFIG);
+ if (systick_freq_scaling)
+ systick_freq_scaling(sdev, 1);
break;
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);
sdev->irq_requested = 0;
@@ -116,12 +141,23 @@ static void systick_set_clock_mode(enum
}
}
+static const struct of_device_id systick_match[] = {
+ { .compatible = "ralink,mt7620-systick", .data = mt7620_freq_scaling},
+ {},
+};
+
static void __init ralink_systick_init(struct device_node *np)
{
+ const struct of_device_id *match;
+
systick.membase = of_iomap(np, 0);
if (!systick.membase)
return;
+ match = of_match_node(systick_match, np);
+ if (match)
+ systick_freq_scaling = match->data;
+
systick_irqaction.name = np->name;
systick.dev.name = np->name;
clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
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