clk: uniphier: add CPU-gear change (cpufreq) support

Core support code for CPU frequency changes, which will be used by
the generic cpufreq driver.

The register view is different from the generic clk-mux; it has
a separate status register, and an update bit to load the register
setting.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 115 insertions, 0 deletions

diff --git a/drivers/clk/uniphier/clk-uniphier-cpugear.c b/drivers/clk/uniphier/clk-uniphier-cpugear.c
new file mode 100644
index 000000000000..9bff26e0cbb0
--- /dev/null
+++ b/drivers/clk/uniphier/clk-uniphier-cpugear.c
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2016 Socionext Inc.
+ *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/regmap.h>
+
+#include "clk-uniphier.h"
+
+#define UNIPHIER_CLK_CPUGEAR_STAT	0	/* status */
+#define UNIPHIER_CLK_CPUGEAR_SET	4	/* set */
+#define UNIPHIER_CLK_CPUGEAR_UPD	8	/* update */
+#define   UNIPHIER_CLK_CPUGEAR_UPD_BIT	BIT(0)
+
+struct uniphier_clk_cpugear {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	unsigned int regbase;
+	unsigned int mask;
+};
+
+#define to_uniphier_clk_cpugear(_hw) \
+			container_of(_hw, struct uniphier_clk_cpugear, hw)
+
+static int uniphier_clk_cpugear_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct uniphier_clk_cpugear *gear = to_uniphier_clk_cpugear(hw);
+	int ret;
+	unsigned int val;
+
+	ret = regmap_write_bits(gear->regmap,
+				gear->regbase + UNIPHIER_CLK_CPUGEAR_SET,
+				gear->mask, index);
+	if (ret)
+		return ret;
+
+	ret = regmap_write_bits(gear->regmap,
+				gear->regbase + UNIPHIER_CLK_CPUGEAR_SET,
+				UNIPHIER_CLK_CPUGEAR_UPD_BIT,
+				UNIPHIER_CLK_CPUGEAR_UPD_BIT);
+	if (ret)
+		return ret;
+
+	return regmap_read_poll_timeout(gear->regmap,
+				gear->regbase + UNIPHIER_CLK_CPUGEAR_UPD,
+				val, !(val & UNIPHIER_CLK_CPUGEAR_UPD_BIT),
+				0, 1);
+}
+
+static u8 uniphier_clk_cpugear_get_parent(struct clk_hw *hw)
+{
+	struct uniphier_clk_cpugear *gear = to_uniphier_clk_cpugear(hw);
+	int num_parents = clk_hw_get_num_parents(hw);
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(gear->regmap,
+			  gear->regbase + UNIPHIER_CLK_CPUGEAR_STAT, &val);
+	if (ret)
+		return ret;
+
+	val &= gear->mask;
+
+	return val < num_parents ? val : -EINVAL;
+}
+
+static const struct clk_ops uniphier_clk_cpugear_ops = {
+	.determine_rate = __clk_mux_determine_rate,
+	.set_parent = uniphier_clk_cpugear_set_parent,
+	.get_parent = uniphier_clk_cpugear_get_parent,
+};
+
+struct clk_hw *uniphier_clk_register_cpugear(struct device *dev,
+					 struct regmap *regmap,
+					 const char *name,
+				const struct uniphier_clk_cpugear_data *data)
+{
+	struct uniphier_clk_cpugear *gear;
+	struct clk_init_data init;
+	int ret;
+
+	gear = devm_kzalloc(dev, sizeof(*gear), GFP_KERNEL);
+	if (!gear)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &uniphier_clk_cpugear_ops;
+	init.flags = CLK_SET_RATE_PARENT;
+	init.parent_names = data->parent_names;
+	init.num_parents = data->num_parents,
+
+	gear->regmap = regmap;
+	gear->regbase = data->regbase;
+	gear->mask = data->mask;
+	gear->hw.init = &init;
+
+	ret = devm_clk_hw_register(dev, &gear->hw);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return &gear->hw;
+}