clk: fixed-factor: Convert into a module platform driver

Adds support for fixed-factor clock providers which have not been
enabled via of_clk_init().

This is required by Device trees overlays that introduce clocks
providers.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
[sboyd@codeaurora.org: Make new private function static, don't
check clk for NULL when unregistering in driver remove]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/clk-fixed-factor.c

@@ -12,6 +12,7 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/of.h>
+#include <linux/platform_device.h>
 
 /*
  * DOC: basic fixed multiplier and divider clock that cannot gate
@@ -147,27 +148,25 @@ static const struct of_device_id set_rate_parent_matches[] = {
 	{ /* Sentinel */ },
 };
 
-/**
- * of_fixed_factor_clk_setup() - Setup function for simple fixed factor clock
- */
-void __init of_fixed_factor_clk_setup(struct device_node *node)
+static struct clk *_of_fixed_factor_clk_setup(struct device_node *node)
 {
 	struct clk *clk;
 	const char *clk_name = node->name;
 	const char *parent_name;
 	unsigned long flags = 0;
 	u32 div, mult;
+	int ret;
 
 	if (of_property_read_u32(node, "clock-div", &div)) {
 		pr_err("%s Fixed factor clock <%s> must have a clock-div property\n",
 			__func__, node->name);
-		return;
+		return ERR_PTR(-EIO);
 	}
 
 	if (of_property_read_u32(node, "clock-mult", &mult)) {
 		pr_err("%s Fixed factor clock <%s> must have a clock-mult property\n",
 			__func__, node->name);
-		return;
+		return ERR_PTR(-EIO);
 	}
 
 	of_property_read_string(node, "clock-output-names", &clk_name);
@@ -178,10 +177,68 @@ void __init of_fixed_factor_clk_setup(struct device_node *node)
 
 	clk = clk_register_fixed_factor(NULL, clk_name, parent_name, flags,
 					mult, div);
-	if (!IS_ERR(clk))
-		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	if (IS_ERR(clk))
+		return clk;
+
+	ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	if (ret) {
+		clk_unregister(clk);
+		return ERR_PTR(ret);
+	}
+
+	return clk;
+}
+
+/**
+ * of_fixed_factor_clk_setup() - Setup function for simple fixed factor clock
+ */
+void __init of_fixed_factor_clk_setup(struct device_node *node)
+{
+	_of_fixed_factor_clk_setup(node);
 }
 EXPORT_SYMBOL_GPL(of_fixed_factor_clk_setup);
 CLK_OF_DECLARE(fixed_factor_clk, "fixed-factor-clock",
 		of_fixed_factor_clk_setup);
+
+static int of_fixed_factor_clk_remove(struct platform_device *pdev)
+{
+	struct clk *clk = platform_get_drvdata(pdev);
+
+	clk_unregister_fixed_factor(clk);
+
+	return 0;
+}
+
+static int of_fixed_factor_clk_probe(struct platform_device *pdev)
+{
+	struct clk *clk;
+
+	/*
+	 * This function is not executed when of_fixed_factor_clk_setup
+	 * succeeded.
+	 */
+	clk = _of_fixed_factor_clk_setup(pdev->dev.of_node);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	platform_set_drvdata(pdev, clk);
+
+	return 0;
+}
+
+static const struct of_device_id of_fixed_factor_clk_ids[] = {
+	{ .compatible = "fixed-factor-clock" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, of_fixed_factor_clk_ids);
+
+static struct platform_driver of_fixed_factor_clk_driver = {
+	.driver = {
+		.name = "of_fixed_factor_clk",
+		.of_match_table = of_fixed_factor_clk_ids,
+	},
+	.probe = of_fixed_factor_clk_probe,
+	.remove = of_fixed_factor_clk_remove,
+};
+builtin_platform_driver(of_fixed_factor_clk_driver);
 #endif