clk: meson: add minimal driver for axg-ao clocks

Add minimal driver AO clocks on meson AXG family. Only ADC related clocks
are supported.

Signed-off-by: Vyacheslav Bocharov <adeep@lexina.in>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220424082159.757622-2-adeep@lexina.in

drivers/clk/meson/Makefile

@@ -5,5 +5,6 @@
 
 obj-$(CONFIG_CLK_MESON_GX) += gxbb.o
 obj-$(CONFIG_CLK_MESON_AXG) += axg.o
+obj-$(CONFIG_CLK_MESON_AXG) += axg-ao.o
 obj-$(CONFIG_CLK_MESON_G12A) += g12a.o
 obj-$(CONFIG_CLK_MESON_G12A) += g12a-ao.o

drivers/clk/meson/axg-ao.c

@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <common.h>
+#include <log.h>
+#include <asm/io.h>
+#include <clk-uclass.h>
+#include <dm.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <dt-bindings/clock/axg-aoclkc.h>
+
+#include "clk_meson.h"
+
+struct meson_clk {
+	struct regmap *map;
+};
+
+#define AO_CLK_GATE0		0x40
+#define AO_SAR_CLK		0x90
+
+static struct meson_gate gates[] = {
+	MESON_GATE(CLKID_AO_SAR_ADC, AO_CLK_GATE0, 7),
+	MESON_GATE(CLKID_AO_SAR_ADC_CLK, AO_SAR_CLK, 7),
+};
+
+static int meson_set_gate(struct clk *clk, bool on)
+{
+	struct meson_clk *priv = dev_get_priv(clk->dev);
+	struct meson_gate *gate;
+
+	gate = &gates[clk->id];
+
+	regmap_update_bits(priv->map, gate->reg,
+			   BIT(gate->bit), on ? BIT(gate->bit) : 0);
+
+	return 0;
+}
+
+static int meson_clk_enable(struct clk *clk)
+{
+	return meson_set_gate(clk, true);
+}
+
+static int meson_clk_disable(struct clk *clk)
+{
+	return meson_set_gate(clk, false);
+}
+
+static int meson_clk_probe(struct udevice *dev)
+{
+	struct meson_clk *priv = dev_get_priv(dev);
+
+	priv->map = syscon_node_to_regmap(dev_ofnode(dev_get_parent(dev)));
+	if (IS_ERR(priv->map))
+		return PTR_ERR(priv->map);
+
+	return 0;
+}
+
+static int meson_clk_request(struct clk *clk)
+{
+	if (clk->id >= ARRAY_SIZE(gates))
+		return -ENOENT;
+
+	return 0;
+}
+
+static struct clk_ops meson_clk_ops = {
+	.disable	= meson_clk_disable,
+	.enable		= meson_clk_enable,
+	.request	= meson_clk_request,
+};
+
+static const struct udevice_id meson_clk_ids[] = {
+	{ .compatible = "amlogic,meson-axg-aoclkc" },
+	{ }
+};
+
+U_BOOT_DRIVER(meson_clk_axg_ao) = {
+	.name		= "meson_clk_axg_ao",
+	.id		= UCLASS_CLK,
+	.of_match	= meson_clk_ids,
+	.priv_auto	= sizeof(struct meson_clk),
+	.ops		= &meson_clk_ops,
+	.probe		= meson_clk_probe,
+};