GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/bootloader/u-boot-2020.01/arch/arm/mach-at91/armv7/timer.c

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+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2007-2008
+ * Stelian Pop <stelian@popies.net>
+ * Lead Tech Design <www.leadtechdesign.com>
+ *
+ * (C) Copyright 2013
+ * Bo Shen <voice.shen@atmel.com>
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/arch/hardware.h>
+#include <asm/arch/at91_pit.h>
+#include <asm/arch/clk.h>
+#include <div64.h>
+
+#if !defined(CONFIG_AT91FAMILY)
+# error You need to define CONFIG_AT91FAMILY in your board config!
+#endif
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * We're using the SAMA5D3x PITC in 32 bit mode, by
+ * setting the 20 bit counter period to its maximum (0xfffff).
+ * (See the relevant data sheets to understand that this really works)
+ *
+ * We do also mimic the typical powerpc way of incrementing
+ * two 32 bit registers called tbl and tbu.
+ *
+ * Those registers increment at 1/16 the main clock rate.
+ */
+
+#define TIMER_LOAD_VAL	0xfffff
+
+/*
+ * Use the PITC in full 32 bit incrementing mode
+ */
+int timer_init(void)
+{
+	at91_pit_t *pit = (at91_pit_t *)ATMEL_BASE_PIT;
+
+	/* Enable PITC Clock */
+	at91_periph_clk_enable(ATMEL_ID_PIT);
+
+	/* Enable PITC */
+	writel(TIMER_LOAD_VAL | AT91_PIT_MR_EN , &pit->mr);
+
+	gd->arch.timer_rate_hz = get_pit_clk_rate() / 16;
+
+	return 0;
+}
+
+/*
+ * Return the number of timer ticks per second.
+ */
+ulong get_tbclk(void)
+{
+	return gd->arch.timer_rate_hz;
+}