clk: Versatile Express clock generators ("osc") driver

This driver provides a common clock framework hardware driver
for Versatile Express clock generators (a.k.a "osc") controlled
via the config bus.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/versatile/Makefile

@@ -2,3 +2,4 @@
 obj-$(CONFIG_ICST)		+= clk-icst.o
 obj-$(CONFIG_ARCH_INTEGRATOR)	+= clk-integrator.o
 obj-$(CONFIG_ARCH_REALVIEW)	+= clk-realview.o
+obj-$(CONFIG_VEXPRESS_CONFIG)	+= clk-vexpress-osc.o

drivers/clk/versatile/clk-vexpress-osc.c

@@ -0,0 +1,146 @@
+/*
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2012 ARM Limited
+ */
+
+#define pr_fmt(fmt) "vexpress-osc: " fmt
+
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/vexpress.h>
+
+struct vexpress_osc {
+	struct vexpress_config_func *func;
+	struct clk_hw hw;
+	unsigned long rate_min;
+	unsigned long rate_max;
+};
+
+#define to_vexpress_osc(osc) container_of(osc, struct vexpress_osc, hw)
+
+static unsigned long vexpress_osc_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct vexpress_osc *osc = to_vexpress_osc(hw);
+	u32 rate;
+
+	vexpress_config_read(osc->func, 0, &rate);
+
+	return rate;
+}
+
+static long vexpress_osc_round_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long *parent_rate)
+{
+	struct vexpress_osc *osc = to_vexpress_osc(hw);
+
+	if (WARN_ON(osc->rate_min && rate < osc->rate_min))
+		rate = osc->rate_min;
+
+	if (WARN_ON(osc->rate_max && rate > osc->rate_max))
+		rate = osc->rate_max;
+
+	return rate;
+}
+
+static int vexpress_osc_set_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long parent_rate)
+{
+	struct vexpress_osc *osc = to_vexpress_osc(hw);
+
+	return vexpress_config_write(osc->func, 0, rate);
+}
+
+static struct clk_ops vexpress_osc_ops = {
+	.recalc_rate = vexpress_osc_recalc_rate,
+	.round_rate = vexpress_osc_round_rate,
+	.set_rate = vexpress_osc_set_rate,
+};
+
+
+struct clk * __init vexpress_osc_setup(struct device *dev)
+{
+	struct clk_init_data init;
+	struct vexpress_osc *osc = kzalloc(sizeof(*osc), GFP_KERNEL);
+
+	if (!osc)
+		return NULL;
+
+	osc->func = vexpress_config_func_get_by_dev(dev);
+	if (!osc->func) {
+		kfree(osc);
+		return NULL;
+	}
+
+	init.name = dev_name(dev);
+	init.ops = &vexpress_osc_ops;
+	init.flags = CLK_IS_ROOT;
+	init.num_parents = 0;
+	osc->hw.init = &init;
+
+	return clk_register(NULL, &osc->hw);
+}
+
+void __init vexpress_osc_of_setup(struct device_node *node)
+{
+	struct clk_init_data init;
+	struct vexpress_osc *osc;
+	struct clk *clk;
+	u32 range[2];
+
+	osc = kzalloc(sizeof(*osc), GFP_KERNEL);
+	if (!osc)
+		goto error;
+
+	osc->func = vexpress_config_func_get_by_node(node);
+	if (!osc->func) {
+		pr_err("Failed to obtain config func for node '%s'!\n",
+				node->name);
+		goto error;
+	}
+
+	if (of_property_read_u32_array(node, "freq-range", range,
+			ARRAY_SIZE(range)) == 0) {
+		osc->rate_min = range[0];
+		osc->rate_max = range[1];
+	}
+
+	of_property_read_string(node, "clock-output-names", &init.name);
+	if (!init.name)
+		init.name = node->name;
+
+	init.ops = &vexpress_osc_ops;
+	init.flags = CLK_IS_ROOT;
+	init.num_parents = 0;
+
+	osc->hw.init = &init;
+
+	clk = clk_register(NULL, &osc->hw);
+	if (IS_ERR(clk)) {
+		pr_err("Failed to register clock '%s'!\n", init.name);
+		goto error;
+	}
+
+	of_clk_add_provider(node, of_clk_src_simple_get, clk);
+
+	pr_debug("Registered clock '%s'\n", init.name);
+
+	return;
+
+error:
+	if (osc->func)
+		vexpress_config_func_put(osc->func);
+	kfree(osc);
+}