clk: qcom: Add support for dummy reset controller

The consumers of the dummy clock provider would require support for dummy
resets, which would make a dummy assert/deassert reset signals. The dummy
reset controller registers for 0-100 reset signals.

The consumers node would have the reset phandle and reset specific pairs
and the reset signal names.

test_node {
	....
	resets = <&clock_gcc GCC_PHY_BCR>;
	reset-names = "phy_reset";
};

Change-Id: I242d2f36a6b4af53c658dbaa7a0f32e46cd3af33
Signed-off-by: Taniya Das <tdas@codeaurora.org>

Documentation/devicetree/bindings/arm/msm/clock-controller-dummy.txt

@@ -9,9 +9,14 @@ Required properties:
 - #clock_cells:		Must be <1>. This will allow the common clock device
 			tree framework to recognize _this_ device node as a
 			clock provider.
+Optional properties:
+- #reset-cells:		Must be <1>. This will allow the common reset device
+			tree framework to recognize _this_ device node as a
+			reset controller provider.
 
 Example:
 	clock_rpm: qcom,rpmcc {
 		compatible = "qcom,dummycc";
 		#clock-cells = <1>;
+		#reset-cells = <1>;
 	};

drivers/clk/qcom/clk-dummy.c

@@ -15,14 +15,18 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/reset-controller.h>
 
 struct clk_dummy {
 	struct clk_hw hw;
+	struct reset_controller_dev reset;
 	unsigned long rrate;
 };
 
 #define to_clk_dummy(_hw)	container_of(_hw, struct clk_dummy, hw)
 
+#define RESET_MAX	100
+
 static int dummy_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 					unsigned long parent_rate)
 {
@@ -58,15 +62,35 @@ struct clk_ops clk_dummy_ops = {
 };
 EXPORT_SYMBOL_GPL(clk_dummy_ops);
 
+static int dummy_reset_assert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	pr_debug("%s\n", __func__);
+	return 0;
+}
+
+static int dummy_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	pr_debug("%s\n", __func__);
+	return 0;
+}
+
+static struct reset_control_ops dummy_reset_ops = {
+	.assert         = dummy_reset_assert,
+	.deassert       = dummy_reset_deassert,
+};
+
 /**
  * clk_register_dummy - register dummy clock with the
  *				   clock framework
  * @dev: device that is registering this clock
  * @name: name of this clock
  * @flags: framework-specific flags
+ * @node: device node
  */
 static struct clk *clk_register_dummy(struct device *dev, const char *name,
-		unsigned long flags)
+		unsigned long flags, struct device_node *node)
 {
 	struct clk_dummy *dummy;
 	struct clk *clk;
@@ -85,8 +109,20 @@ static struct clk *clk_register_dummy(struct device *dev, const char *name,
 
 	/* register the clock */
 	clk = clk_register(dev, &dummy->hw);
-	if (IS_ERR(clk))
+	if (IS_ERR(clk)) {
 		kfree(dummy);
+		return clk;
+	}
+
+	dummy->reset.of_node = node;
+	dummy->reset.ops = &dummy_reset_ops;
+	dummy->reset.nr_resets = RESET_MAX;
+
+	if (reset_controller_register(&dummy->reset))
+		pr_err("Failed to register reset controller for %s\n", name);
+	else
+		pr_info("Successfully registered a dummy reset controller for %s\n",
+								name);
 
 	return clk;
 }
@@ -101,10 +137,15 @@ static void of_dummy_clk_setup(struct device_node *node)
 
 	of_property_read_string(node, "clock-output-names", &clk_name);
 
-	clk = clk_register_dummy(NULL, clk_name, 0);
+	clk = clk_register_dummy(NULL, clk_name, 0, node);
 	if (!IS_ERR(clk))
 		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	else {
+		pr_err("Failed to register dummy clock controller for %s\n",
+								clk_name);
+		return;
+	}
 
-	pr_info("%s: Dummy clock registered\n", clk_name);
+	pr_info("Successfully registered dummy clock for %s\n", clk_name);
 }
 CLK_OF_DECLARE(dummy_clk, "qcom,dummycc", of_dummy_clk_setup);