[PATCH v1 2/5] clk: imx: add simple regmap-backed clock mux

[Sven Van Asbroeck]

On the imx6 QuadPlus, some clocktree muxes have control bits located
in the GPR area. This area is already modelled as a syscon regmap.

To control these muxes, add a simple regmap-backed clock mux.

Signed-off-by: Sven Van Asbroeck <TheSven73@xxxxxxxxx>
---

Tree: v5.8-rc4

To: Shawn Guo <shawnguo@xxxxxxxxxx>
To: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Cc: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
Cc: Fabio Estevam <festevam@xxxxxxxxx>
Cc: NXP Linux Team <linux-imx@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-clk@xxxxxxxxxxxxxxx

 drivers/clk/imx/Makefile         |   1 +
 drivers/clk/imx/clk-mux-regmap.c | 110 +++++++++++++++++++++++++++++++
 drivers/clk/imx/clk.h            |   7 ++
 3 files changed, 118 insertions(+)
 create mode 100644 drivers/clk/imx/clk-mux-regmap.c

diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
index 928f874c73d2..3d36740c1efd 100644
--- a/drivers/clk/imx/Makefile
+++ b/drivers/clk/imx/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_MXC_CLK) += \
 	clk-pllv3.o \
 	clk-pllv4.o \
 	clk-sscg-pll.o \
+	clk-mux-regmap.o \
 	clk-pll14xx.o
 
 obj-$(CONFIG_MXC_CLK_SCU) += \
diff --git a/drivers/clk/imx/clk-mux-regmap.c b/drivers/clk/imx/clk-mux-regmap.c
new file mode 100644
index 000000000000..ba5fde525999
--- /dev/null
+++ b/drivers/clk/imx/clk-mux-regmap.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Sven Van Asbroeck
+ *
+ * Simple clock multiplexer, backed by a regmap
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include "clk.h"
+
+struct clk_mux_regmap {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	unsigned int reg;
+	u8 shift;
+	u32 mask;
+};
+
+#define to_clk_mux_regmap(_hw) container_of(_hw, struct clk_mux_regmap, hw)
+
+static u8 clk_regmap_read_index(struct clk_mux_regmap *clk)
+{
+	unsigned int val;
+
+	if (regmap_read(clk->regmap, clk->reg, &val))
+		return 0;
+
+	val >>= clk->shift;
+	val &= clk->mask;
+
+	return (u8)val;
+}
+
+static u8 clk_mux_regmap_get_parent(struct clk_hw *hw)
+{
+	struct clk_mux_regmap *clk = to_clk_mux_regmap(hw);
+
+	return clk_regmap_read_index(clk);
+}
+
+static int clk_mux_regmap_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_mux_regmap *clk = to_clk_mux_regmap(hw);
+
+	return regmap_update_bits(clk->regmap, clk->reg,
+				  clk->mask << clk->shift,
+				  (unsigned int)index << clk->shift);
+}
+
+static int clk_mux_regmap_determine_rate(struct clk_hw *hw,
+					 struct clk_rate_request *req)
+{
+	struct clk_mux_regmap *clk = to_clk_mux_regmap(hw);
+	struct clk_hw *parent;
+	u8 index;
+
+	index = clk_regmap_read_index(clk);
+	parent = clk_hw_get_parent_by_index(hw, index);
+	if (!parent)
+		return -EINVAL;
+	req->rate = clk_hw_get_rate(parent);
+
+	return 0;
+}
+
+static const struct clk_ops clk_mux_regmap_ops = {
+	.get_parent = clk_mux_regmap_get_parent,
+	.set_parent = clk_mux_regmap_set_parent,
+	.determine_rate = clk_mux_regmap_determine_rate,
+};
+
+struct clk_hw *
+imx_clk_hw_mux_regmap(const char *name, struct regmap *regmap, unsigned int reg,
+		      u8 shift, u8 width, const char * const *parent_names,
+		      int num_parents)
+{
+	struct clk_mux_regmap *clk_regmap;
+	struct clk_init_data init = {};
+	struct clk_hw *hw;
+	int ret;
+
+	if (num_parents > (1 << width))
+		return ERR_PTR(-EINVAL);
+
+	clk_regmap = kzalloc(sizeof(*clk_regmap), GFP_KERNEL);
+	if (!clk_regmap)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;
+	init.ops = &clk_mux_regmap_ops;
+	clk_regmap->regmap = regmap;
+	clk_regmap->reg = reg;
+	clk_regmap->shift = shift;
+	clk_regmap->mask = BIT(width) - 1;
+	clk_regmap->hw.init = &init;
+
+	hw = &clk_regmap->hw;
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		kfree(clk_regmap);
+		hw = ERR_PTR(ret);
+	}
+
+	return hw;
+}
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 16adbc34e05f..4df766abbe16 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -5,6 +5,8 @@
 #include <linux/spinlock.h>
 #include <linux/clk-provider.h>
 
+struct regmap;
+
 #define IMX_CLK_GATE2_SINGLE_BIT	1
 
 extern spinlock_t imx_ccm_lock;
@@ -447,6 +449,11 @@ static inline struct clk_hw *imx_dev_clk_hw_mux(struct device *dev,
 			reg, shift, width, 0, &imx_ccm_lock);
 }
 
+struct clk_hw *
+imx_clk_hw_mux_regmap(const char *name, struct regmap *regmap, unsigned int reg,
+		      u8 shift, u8 width, const char * const *parent_names,
+		      int num_parents);
+
 static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
 			u8 shift, u8 width, const char * const *parents,
 			int num_parents)
-- 
2.17.1