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

2026-09-06 03:52:57 +08:00
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+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2000-2004
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ */
+
+#include <common.h>
+#include <mpc8xx.h>
+#include <asm/processor.h>
+#include <asm/io.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * get_clocks() fills in gd->cpu_clock depending on CONFIG_8xx_GCLK_FREQ
+ */
+int get_clocks(void)
+{
+	immap_t __iomem *immap = (immap_t __iomem *)CONFIG_SYS_IMMR;
+	uint sccr = in_be32(&immap->im_clkrst.car_sccr);
+	uint divider = 1 << (((sccr & SCCR_DFBRG11) >> 11) * 2);
+
+	/*
+	 * If for some reason measuring the gclk frequency won't
+	 * work, we return the hardwired value.
+	 * (For example, the cogent CMA286-60 CPU module has no
+	 * separate oscillator for PITRTCLK)
+	 */
+	gd->cpu_clk = CONFIG_8xx_GCLK_FREQ;
+
+	if ((sccr & SCCR_EBDF11) == 0) {
+		/* No Bus Divider active */
+		gd->bus_clk = gd->cpu_clk;
+	} else {
+		/* The MPC8xx has only one BDF: half clock speed */
+		gd->bus_clk = gd->cpu_clk / 2;
+	}
+
+	gd->arch.brg_clk = gd->cpu_clk / divider;
+
+	return 0;
+}