1 files changed, 110 insertions, 0 deletions
diff --git a/arch/metag/kernel/clock.c b/arch/metag/kernel/clock.c
new file mode 100644
index 000000000..6339c9c6d
--- /dev/null
+++ b/arch/metag/kernel/clock.c
@@ -0,0 +1,110 @@
+/*
+ * arch/metag/kernel/clock.c
+ *
+ * Copyright (C) 2012 Imagination Technologies Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#include <asm/param.h>
+#include <asm/clock.h>
+
+struct meta_clock_desc _meta_clock;
+
+/* Default machine get_core_freq callback. */
+static unsigned long get_core_freq_default(void)
+{
+#ifdef CONFIG_METAG_META21
+	/*
+	 * Meta 2 cores divide down the core clock for the Meta timers, so we
+	 * can estimate the core clock from the divider.
+	 */
+	return (metag_in32(EXPAND_TIMER_DIV) + 1) * 1000000;
+#else
+	/*
+	 * On Meta 1 we don't know the core clock, but assuming the Meta timer
+	 * is correct it can be estimated based on loops_per_jiffy.
+	 */
+	return (loops_per_jiffy * HZ * 5) >> 1;
+#endif
+}
+
+static struct clk *clk_core;
+
+/* Clk based get_core_freq callback. */
+static unsigned long get_core_freq_clk(void)
+{
+	return clk_get_rate(clk_core);
+}
+
+/**
+ * init_metag_core_clock() - Set up core clock from devicetree.
+ *
+ * Checks to see if a "core" clock is provided in the device tree, and overrides
+ * the get_core_freq callback to use it.
+ */
+static void __init init_metag_core_clock(void)
+{
+	/*
+	 * See if a core clock is provided by the devicetree (and
+	 * registered by the init callback above).
+	 */
+	struct device_node *node;
+	node = of_find_compatible_node(NULL, NULL, "img,meta");
+	if (!node) {
+		pr_warn("%s: no compatible img,meta DT node found\n",
+			__func__);
+		return;
+	}
+
+	clk_core = of_clk_get_by_name(node, "core");
+	if (IS_ERR(clk_core)) {
+		pr_warn("%s: no core clock found in DT\n",
+			__func__);
+		return;
+	}
+
+	/*
+	 * Override the core frequency callback to use
+	 * this clk.
+	 */
+	_meta_clock.get_core_freq = get_core_freq_clk;
+}
+
+/**
+ * init_metag_clocks() - Set up clocks from devicetree.
+ *
+ * Set up important clocks from device tree. In particular any needed for clock
+ * sources.
+ */
+void __init init_metag_clocks(void)
+{
+	init_metag_core_clock();
+
+	pr_info("Core clock frequency: %lu Hz\n", get_coreclock());
+}
+
+/**
+ * setup_meta_clocks() - Early set up of the Meta clock.
+ * @desc:	Clock descriptor usually provided by machine description
+ *
+ * Ensures all callbacks are valid.
+ */
+void __init setup_meta_clocks(struct meta_clock_desc *desc)
+{
+	/* copy callbacks */
+	if (desc)
+		_meta_clock = *desc;
+
+	/* set fallback functions */
+	if (!_meta_clock.get_core_freq)
+		_meta_clock.get_core_freq = get_core_freq_default;
+}
+