clk: sunxi: Add A23 APB0 divider clock support

The A23 has an almost identical PRCM clock tree. The difference in
the APB0 clock is the smallest divisor is 1, instead of 2.

This patch adds a separate sun8i-a23-apb0-clk driver to support it.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Documentation/devicetree/bindings/clock/sunxi.txt

@@ -28,6 +28,7 @@ Required properties:
 	"allwinner,sun8i-a23-ahb1-gates-clk" - for the AHB1 gates on A23
 	"allwinner,sun4i-a10-apb0-clk" - for the APB0 clock
 	"allwinner,sun6i-a31-apb0-clk" - for the APB0 clock on A31
+	"allwinner,sun8i-a23-apb0-clk" - for the APB0 clock on A23
 	"allwinner,sun4i-a10-apb0-gates-clk" - for the APB0 gates on A10
 	"allwinner,sun5i-a13-apb0-gates-clk" - for the APB0 gates on A13
 	"allwinner,sun5i-a10s-apb0-gates-clk" - for the APB0 gates on A10s

drivers/clk/sunxi/Makefile

@@ -6,4 +6,6 @@ obj-y += clk-sunxi.o clk-factors.o
 obj-y += clk-a10-hosc.o
 obj-y += clk-a20-gmac.o
 
-obj-$(CONFIG_MFD_SUN6I_PRCM) += clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o
+obj-$(CONFIG_MFD_SUN6I_PRCM) += \
+	clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o \
+	clk-sun8i-apb0.o

drivers/clk/sunxi/clk-sun8i-apb0.c

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2014 Chen-Yu Tsai
+ * Author: Chen-Yu Tsai <wens@csie.org>
+ *
+ * Allwinner A23 APB0 clock driver
+ *
+ * License Terms: GNU General Public License v2
+ *
+ * Based on clk-sun6i-apb0.c
+ * Allwinner A31 APB0 clock driver
+ *
+ * Copyright (C) 2014 Free Electrons
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+static int sun8i_a23_apb0_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	const char *clk_name = np->name;
+	const char *clk_parent;
+	struct resource *r;
+	void __iomem *reg;
+	struct clk *clk;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	reg = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(reg))
+		return PTR_ERR(reg);
+
+	clk_parent = of_clk_get_parent_name(np, 0);
+	if (!clk_parent)
+		return -EINVAL;
+
+	of_property_read_string(np, "clock-output-names", &clk_name);
+
+	/* The A23 APB0 clock is a standard 2 bit wide divider clock */
+	clk = clk_register_divider(&pdev->dev, clk_name, clk_parent, 0, reg,
+				   0, 2, CLK_DIVIDER_POWER_OF_TWO, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	return of_clk_add_provider(np, of_clk_src_simple_get, clk);
+}
+
+const struct of_device_id sun8i_a23_apb0_clk_dt_ids[] = {
+	{ .compatible = "allwinner,sun8i-a23-apb0-clk" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver sun8i_a23_apb0_clk_driver = {
+	.driver = {
+		.name = "sun8i-a23-apb0-clk",
+		.owner = THIS_MODULE,
+		.of_match_table = sun8i_a23_apb0_clk_dt_ids,
+	},
+	.probe = sun8i_a23_apb0_clk_probe,
+};
+module_platform_driver(sun8i_a23_apb0_clk_driver);
+
+MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
+MODULE_DESCRIPTION("Allwinner A23 APB0 clock Driver");
+MODULE_LICENSE("GPL v2");