clk: Add {devm_}clk_hw_{register,unregister}() APIs

We've largely split the clk consumer and provider APIs along
struct clk and struct clk_hw, but clk_register() still returns a
struct clk pointer for each struct clk_hw that's registered.
Eventually we'd like to only allocate struct clks when there's a
user, because struct clk is per-user now, so clk_register() needs
to change.

Let's add new APIs to register struct clk_hws, but this time
we'll hide the struct clk from the caller by returning an int
error code. Also add an unregistration API that takes the clk_hw
structure that was passed to the registration API. This way
provider drivers never have to deal with a struct clk pointer
unless they're using the clk consumer APIs.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

Documentation/driver-model/devres.txt

@@ -236,6 +236,7 @@ certainly invest a bit more effort into libata core layer).
 CLOCK
   devm_clk_get()
   devm_clk_put()
+  devm_clk_hw_register()
 
 DMA
   dmam_alloc_coherent()

drivers/clk/clk.c

@@ -2536,6 +2536,22 @@ fail_out:
 }
 EXPORT_SYMBOL_GPL(clk_register);
 
+/**
+ * clk_hw_register - register a clk_hw and return an error code
+ * @dev: device that is registering this clock
+ * @hw: link to hardware-specific clock data
+ *
+ * clk_hw_register is the primary interface for populating the clock tree with
+ * new clock nodes. It returns an integer equal to zero indicating success or
+ * less than zero indicating failure. Drivers must test for an error code after
+ * calling clk_hw_register().
+ */
+int clk_hw_register(struct device *dev, struct clk_hw *hw)
+{
+	return PTR_ERR_OR_ZERO(clk_register(dev, hw));
+}
+EXPORT_SYMBOL_GPL(clk_hw_register);
+
 /* Free memory allocated for a clock. */
 static void __clk_release(struct kref *ref)
 {
@@ -2637,11 +2653,26 @@ unlock:
 }
 EXPORT_SYMBOL_GPL(clk_unregister);
 
+/**
+ * clk_hw_unregister - unregister a currently registered clk_hw
+ * @hw: hardware-specific clock data to unregister
+ */
+void clk_hw_unregister(struct clk_hw *hw)
+{
+	clk_unregister(hw->clk);
+}
+EXPORT_SYMBOL_GPL(clk_hw_unregister);
+
 static void devm_clk_release(struct device *dev, void *res)
 {
 	clk_unregister(*(struct clk **)res);
 }
 
+static void devm_clk_hw_release(struct device *dev, void *res)
+{
+	clk_hw_unregister(*(struct clk_hw **)res);
+}
+
 /**
  * devm_clk_register - resource managed clk_register()
  * @dev: device that is registering this clock
@@ -2672,6 +2703,36 @@ struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
 }
 EXPORT_SYMBOL_GPL(devm_clk_register);
 
+/**
+ * devm_clk_hw_register - resource managed clk_hw_register()
+ * @dev: device that is registering this clock
+ * @hw: link to hardware-specific clock data
+ *
+ * Managed clk_hw_register(). Clocks returned from this function are
+ * automatically clk_hw_unregister()ed on driver detach. See clk_hw_register()
+ * for more information.
+ */
+int devm_clk_hw_register(struct device *dev, struct clk_hw *hw)
+{
+	struct clk_hw **hwp;
+	int ret;
+
+	hwp = devres_alloc(devm_clk_hw_release, sizeof(*hwp), GFP_KERNEL);
+	if (!hwp)
+		return -ENOMEM;
+
+	ret = clk_hw_register(dev, hw);
+	if (!ret) {
+		*hwp = hw;
+		devres_add(dev, hwp);
+	} else {
+		devres_free(hwp);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_clk_hw_register);
+
 static int devm_clk_match(struct device *dev, void *res, void *data)
 {
 	struct clk *c = res;
@@ -2680,6 +2741,15 @@ static int devm_clk_match(struct device *dev, void *res, void *data)
 	return c == data;
 }
 
+static int devm_clk_hw_match(struct device *dev, void *res, void *data)
+{
+	struct clk_hw *hw = res;
+
+	if (WARN_ON(!hw))
+		return 0;
+	return hw == data;
+}
+
 /**
  * devm_clk_unregister - resource managed clk_unregister()
  * @clk: clock to unregister
@@ -2694,6 +2764,22 @@ void devm_clk_unregister(struct device *dev, struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(devm_clk_unregister);
 
+/**
+ * devm_clk_hw_unregister - resource managed clk_hw_unregister()
+ * @dev: device that is unregistering the hardware-specific clock data
+ * @hw: link to hardware-specific clock data
+ *
+ * Unregister a clk_hw registered with devm_clk_hw_register(). Normally
+ * this function will not need to be called and the resource management
+ * code will ensure that the resource is freed.
+ */
+void devm_clk_hw_unregister(struct device *dev, struct clk_hw *hw)
+{
+	WARN_ON(devres_release(dev, devm_clk_hw_release, devm_clk_hw_match,
+				hw));
+}
+EXPORT_SYMBOL_GPL(devm_clk_hw_unregister);
+
 /*
  * clkdev helpers
  */

include/linux/clk-provider.h

@@ -655,9 +655,15 @@ struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
 struct clk *clk_register(struct device *dev, struct clk_hw *hw);
 struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw);
 
+int __must_check clk_hw_register(struct device *dev, struct clk_hw *hw);
+int __must_check devm_clk_hw_register(struct device *dev, struct clk_hw *hw);
+
 void clk_unregister(struct clk *clk);
 void devm_clk_unregister(struct device *dev, struct clk *clk);
 
+void clk_hw_unregister(struct clk_hw *hw);
+void devm_clk_hw_unregister(struct device *dev, struct clk_hw *hw);
+
 /* helper functions */
 const char *__clk_get_name(const struct clk *clk);
 const char *clk_hw_get_name(const struct clk_hw *hw);