193 lines
5.1 KiB
Diff
193 lines
5.1 KiB
Diff
From 3b511d972b556712f89ccc68825c0ec8f398dc5c Mon Sep 17 00:00:00 2001
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From: John Crispin <blogic@openwrt.org>
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Date: Sun, 28 Jul 2013 13:46:09 +0200
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Subject: [PATCH 11/25] MIPS: ralink: add support for systick timer found on
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newer ralink SoC
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Newer Ralink SoC (MT7620x and RT5350) have a 50KHz clock that runs independent
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of the SoC master clock. If we want to automatic frequency scaling to work we
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need to use the systick timer as the clock source.
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Signed-off-by: John Crispin <blogic@openwrt.org>
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---
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arch/mips/ralink/Kconfig | 7 ++
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arch/mips/ralink/Makefile | 2 +
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arch/mips/ralink/cevt-rt3352.c | 145 ++++++++++++++++++++++++++++++++++++++++
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3 files changed, 154 insertions(+)
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create mode 100644 arch/mips/ralink/cevt-rt3352.c
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--- a/arch/mips/ralink/Kconfig
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+++ b/arch/mips/ralink/Kconfig
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@@ -1,5 +1,12 @@
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if RALINK
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+config CLKEVT_RT3352
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+ bool "Systick Clockevent source"
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+ depends on SOC_RT305X || SOC_MT7620
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+ default y
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+ select CLKSRC_OF
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+ select CLKSRC_MMIO
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+
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choice
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prompt "Ralink SoC selection"
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default SOC_RT305X
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--- a/arch/mips/ralink/Makefile
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+++ b/arch/mips/ralink/Makefile
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@@ -8,6 +8,8 @@
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obj-y := prom.o of.o reset.o clk.o irq.o timer.o
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+obj-$(CONFIG_CLKEVT_RT3352) += cevt-rt3352.o
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+
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obj-$(CONFIG_SOC_RT288X) += rt288x.o
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obj-$(CONFIG_SOC_RT305X) += rt305x.o
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obj-$(CONFIG_SOC_RT3883) += rt3883.o
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--- /dev/null
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+++ b/arch/mips/ralink/cevt-rt3352.c
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@@ -0,0 +1,145 @@
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+/*
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+ * This file is subject to the terms and conditions of the GNU General Public
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+ * License. See the file "COPYING" in the main directory of this archive
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+ * for more details.
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+ *
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+ * Copyright (C) 2013 by John Crispin <blogic@openwrt.org>
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+ */
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+
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+#include <linux/clockchips.h>
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+#include <linux/clocksource.h>
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+#include <linux/interrupt.h>
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+#include <linux/reset.h>
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+#include <linux/init.h>
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+#include <linux/time.h>
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+#include <linux/of.h>
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+#include <linux/of_irq.h>
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+#include <linux/of_address.h>
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+
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+#include <asm/mach-ralink/ralink_regs.h>
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+
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+#define SYSTICK_FREQ (50 * 1000)
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+
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+#define SYSTICK_CONFIG 0x00
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+#define SYSTICK_COMPARE 0x04
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+#define SYSTICK_COUNT 0x08
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+
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+/* route systick irq to mips irq 7 instead of the r4k-timer */
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+#define CFG_EXT_STK_EN 0x2
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+/* enable the counter */
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+#define CFG_CNT_EN 0x1
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+
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+struct systick_device {
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+ void __iomem *membase;
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+ struct clock_event_device dev;
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+ int irq_requested;
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+ int freq_scale;
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+};
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+
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+static void systick_set_clock_mode(enum clock_event_mode mode,
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+ struct clock_event_device *evt);
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+
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+static int systick_next_event(unsigned long delta,
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+ struct clock_event_device *evt)
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+{
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+ struct systick_device *sdev;
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+ u32 count;
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+
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+ sdev = container_of(evt, struct systick_device, dev);
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+ count = ioread32(sdev->membase + SYSTICK_COUNT);
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+ count = (count + delta) % SYSTICK_FREQ;
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+ iowrite32(count + delta, sdev->membase + SYSTICK_COMPARE);
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+
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+ return 0;
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+}
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+
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+static void systick_event_handler(struct clock_event_device *dev)
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+{
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+ /* noting to do here */
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+}
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+
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+static irqreturn_t systick_interrupt(int irq, void *dev_id)
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+{
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+ struct clock_event_device *dev = (struct clock_event_device *) dev_id;
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+
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+ dev->event_handler(dev);
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+
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+ return IRQ_HANDLED;
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+}
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+
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+static struct systick_device systick = {
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+ .dev = {
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+ /*
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+ * cevt-r4k uses 300, make sure systick
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+ * gets used if available
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+ */
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+ .rating = 310,
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+ .features = CLOCK_EVT_FEAT_ONESHOT,
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+ .set_next_event = systick_next_event,
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+ .set_mode = systick_set_clock_mode,
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+ .event_handler = systick_event_handler,
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+ },
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+};
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+
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+static struct irqaction systick_irqaction = {
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+ .handler = systick_interrupt,
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+ .flags = IRQF_PERCPU | IRQF_TIMER,
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+ .dev_id = &systick.dev,
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+};
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+
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+static void systick_set_clock_mode(enum clock_event_mode mode,
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+ struct clock_event_device *evt)
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+{
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+ struct systick_device *sdev;
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+
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+ sdev = container_of(evt, struct systick_device, dev);
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+
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+ switch (mode) {
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+ case CLOCK_EVT_MODE_ONESHOT:
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+ if (!sdev->irq_requested)
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+ setup_irq(systick.dev.irq, &systick_irqaction);
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+ sdev->irq_requested = 1;
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+ iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
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+ systick.membase + SYSTICK_CONFIG);
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+ break;
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+
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+ case CLOCK_EVT_MODE_SHUTDOWN:
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+ if (sdev->irq_requested)
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+ free_irq(systick.dev.irq, &systick_irqaction);
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+ sdev->irq_requested = 0;
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+ iowrite32(0, systick.membase + SYSTICK_CONFIG);
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+ break;
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+
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+ default:
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+ pr_err("%s: Unhandeled mips clock_mode\n", systick.dev.name);
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+ break;
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+ }
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+}
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+
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+static void __init ralink_systick_init(struct device_node *np)
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+{
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+ systick.membase = of_iomap(np, 0);
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+ if (!systick.membase)
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+ return;
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+
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+ systick_irqaction.name = np->name;
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+ systick.dev.name = np->name;
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+ clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
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+ systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
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+ systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
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+ systick.dev.irq = irq_of_parse_and_map(np, 0);
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+ if (!systick.dev.irq) {
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+ pr_err("%s: request_irq failed", np->name);
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+ return;
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+ }
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+
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+ clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
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+ SYSTICK_FREQ, 301, 16, clocksource_mmio_readl_up);
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+
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+ clockevents_register_device(&systick.dev);
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+
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+ pr_info("%s: runing - mult: %d, shift: %d\n",
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+ np->name, systick.dev.mult, systick.dev.shift);
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+}
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+
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+CLOCKSOURCE_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
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