MIPS: Loongson 2F: Add CPU frequency scaling support

Loongson 2F supports CPU clock scaling. When put it into wait mode by
setting the frequency as ZERO it will stay in this mode until an external
interrupt wakes the CPU again.

To enable clock scaling support, an external timer of a known stable rate
is required.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: cpufreq@vger.kernel.org,
Cc: Dave Jones <davej@redhat.com>,
Cc: Dominik Brodowski <linux@dominikbrodowski.net>,
Cc: yanh@lemote.com
Cc: huhb@lemote.com,
Patchwork: http://patchwork.linux-mips.org/patch/660/
Patchwork: http://patchwork.linux-mips.org/patch/751/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/arch/mips/include/asm/clock.h b/arch/mips/include/asm/clock.h
new file mode 100644
index 000000000000..83894aa7932c
--- /dev/null
+++ b/arch/mips/include/asm/clock.h
@@ -0,0 +1,64 @@
+#ifndef __ASM_MIPS_CLOCK_H
+#define __ASM_MIPS_CLOCK_H
+
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/seq_file.h>
+#include <linux/clk.h>
+
+extern void (*cpu_wait) (void);
+
+struct clk;
+
+struct clk_ops {
+	void (*init) (struct clk *clk);
+	void (*enable) (struct clk *clk);
+	void (*disable) (struct clk *clk);
+	void (*recalc) (struct clk *clk);
+	int (*set_rate) (struct clk *clk, unsigned long rate, int algo_id);
+	long (*round_rate) (struct clk *clk, unsigned long rate);
+};
+
+struct clk {
+	struct list_head node;
+	const char *name;
+	int id;
+	struct module *owner;
+
+	struct clk *parent;
+	struct clk_ops *ops;
+
+	struct kref kref;
+
+	unsigned long rate;
+	unsigned long flags;
+};
+
+#define CLK_ALWAYS_ENABLED	(1 << 0)
+#define CLK_RATE_PROPAGATES	(1 << 1)
+
+/* Should be defined by processor-specific code */
+void arch_init_clk_ops(struct clk_ops **, int type);
+
+int clk_init(void);
+
+int __clk_enable(struct clk *);
+void __clk_disable(struct clk *);
+
+void clk_recalc_rate(struct clk *);
+
+int clk_register(struct clk *);
+void clk_unregister(struct clk *);
+
+/* the exported API, in addition to clk_set_rate */
+/**
+ * clk_set_rate_ex - set the clock rate for a clock source, with additional parameter
+ * @clk: clock source
+ * @rate: desired clock rate in Hz
+ * @algo_id: algorithm id to be passed down to ops->set_rate
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_rate_ex(struct clk *clk, unsigned long rate, int algo_id);
+
+#endif				/* __ASM_MIPS_CLOCK_H */