clk: meson: add g12a cpu dynamic divider driver

Add a clock driver for the cpu dynamic divider, this divider needs
to have a flag set before setting the divider value then removed
while writing the new value to the register.

This drivers implements this behavior and will be used essentially
on the Amlogic G12A and G12B SoCs for cpu clock trees.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

drivers/clk/meson/Kconfig

@@ -36,6 +36,10 @@ config COMMON_CLK_MESON_EE_CLKC
 	tristate
 	select COMMON_CLK_MESON_REGMAP
 
+config COMMON_CLK_MESON_CPU_DYNDIV
+	tristate
+	select COMMON_CLK_MESON_REGMAP
+
 config COMMON_CLK_MESON8B
 	bool
 	depends on ARCH_MESON
@@ -98,6 +102,7 @@ config COMMON_CLK_G12A
 	select COMMON_CLK_MESON_PLL
 	select COMMON_CLK_MESON_AO_CLKC
 	select COMMON_CLK_MESON_EE_CLKC
+	select COMMON_CLK_MESON_CPU_DYNDIV
 	select MFD_SYSCON
 	help
 	  Support for the clock controller on Amlogic S905D2, S905X2 and S905Y2

drivers/clk/meson/Makefile

@@ -2,6 +2,7 @@
 # Amlogic clock drivers
 
 obj-$(CONFIG_COMMON_CLK_MESON_AO_CLKC) += meson-aoclk.o
+obj-$(CONFIG_COMMON_CLK_MESON_CPU_DYNDIV) += clk-cpu-dyndiv.o
 obj-$(CONFIG_COMMON_CLK_MESON_DUALDIV) += clk-dualdiv.o
 obj-$(CONFIG_COMMON_CLK_MESON_EE_CLKC) += meson-eeclk.o
 obj-$(CONFIG_COMMON_CLK_MESON_MPLL) += clk-mpll.o

drivers/clk/meson/clk-cpu-dyndiv.c

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Copyright (c) 2019 BayLibre, SAS.
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+
+#include "clk-regmap.h"
+#include "clk-cpu-dyndiv.h"
+
+static inline struct meson_clk_cpu_dyndiv_data *
+meson_clk_cpu_dyndiv_data(struct clk_regmap *clk)
+{
+	return (struct meson_clk_cpu_dyndiv_data *)clk->data;
+}
+
+static unsigned long meson_clk_cpu_dyndiv_recalc_rate(struct clk_hw *hw,
+						      unsigned long prate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_cpu_dyndiv_data *data = meson_clk_cpu_dyndiv_data(clk);
+
+	return divider_recalc_rate(hw, prate,
+				   meson_parm_read(clk->map, &data->div),
+				   NULL, 0, data->div.width);
+}
+
+static long meson_clk_cpu_dyndiv_round_rate(struct clk_hw *hw,
+					    unsigned long rate,
+					    unsigned long *prate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_cpu_dyndiv_data *data = meson_clk_cpu_dyndiv_data(clk);
+
+	return divider_round_rate(hw, rate, prate, NULL, data->div.width, 0);
+}
+
+static int meson_clk_cpu_dyndiv_set_rate(struct clk_hw *hw, unsigned long rate,
+					  unsigned long parent_rate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_cpu_dyndiv_data *data = meson_clk_cpu_dyndiv_data(clk);
+	unsigned int val;
+	int ret;
+
+	ret = divider_get_val(rate, parent_rate, NULL, data->div.width, 0);
+	if (ret < 0)
+		return ret;
+
+	val = (unsigned int)ret << data->div.shift;
+
+	/* Write the SYS_CPU_DYN_ENABLE bit before changing the divider */
+	meson_parm_write(clk->map, &data->dyn, 1);
+
+	/* Update the divider while removing the SYS_CPU_DYN_ENABLE bit */
+	return regmap_update_bits(clk->map, data->div.reg_off,
+				  SETPMASK(data->div.width, data->div.shift) |
+				  SETPMASK(data->dyn.width, data->dyn.shift),
+				  val);
+};
+
+const struct clk_ops meson_clk_cpu_dyndiv_ops = {
+	.recalc_rate = meson_clk_cpu_dyndiv_recalc_rate,
+	.round_rate = meson_clk_cpu_dyndiv_round_rate,
+	.set_rate = meson_clk_cpu_dyndiv_set_rate,
+};
+EXPORT_SYMBOL_GPL(meson_clk_cpu_dyndiv_ops);
+
+MODULE_DESCRIPTION("Amlogic CPU Dynamic Clock divider");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_LICENSE("GPL v2");

drivers/clk/meson/clk-cpu-dyndiv.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019 BayLibre, SAS.
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ */
+
+#ifndef __MESON_CLK_CPU_DYNDIV_H
+#define __MESON_CLK_CPU_DYNDIV_H
+
+#include <linux/clk-provider.h>
+#include "parm.h"
+
+struct meson_clk_cpu_dyndiv_data {
+	struct parm div;
+	struct parm dyn;
+};
+
+extern const struct clk_ops meson_clk_cpu_dyndiv_ops;
+
+#endif /* __MESON_CLK_CPU_DYNDIV_H */