[PATCH 2/7] OMAP clock: add notifier infrastructure

[Paul Walmsley <paul@pwsan.com>]

Add the clock notifier infrastructure.  The external function exposed here
is omap_clk_notify_downstream().  This is intended to be used by
architecture-specific clk_set_rate() and clk_set_parent() functions, e.g.,
omap2_clk_set_rate().

Signed-off-by: Paul Walmsley <paul@pwsan.com>
---
 arch/arm/plat-omap/clock.c              |   81 +++++++++++++++++++++++++++++++
 arch/arm/plat-omap/include/mach/clock.h |    1 
 2 files changed, 82 insertions(+), 0 deletions(-)

diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c
index 4c2ed56..73bef03 100644
--- a/arch/arm/plat-omap/clock.c
+++ b/arch/arm/plat-omap/clock.c
@@ -173,6 +173,64 @@ void omap_clk_del_child(struct clk *clk, struct clk *clk2)
 	}
 }
 
+/**
+ * omap_clk_notify - call clk notifier chain
+ * @clk: struct clk * that is changing rate
+ * @msg: clk notifier type (i.e., CLK_POST_RATE_CHANGE; see mach/clock.h)
+ * @old_rate: old rate
+ * @new_rate: new rate
+ *
+ * Triggers a notifier call chain on the post-clk-rate-change notifier
+ * for clock 'clk'.  Passes a pointer to the struct clk and the
+ * previous and current rates to the notifier callback.  Intended to be
+ * called by internal clock code only.  No return value.
+ */
+static int omap_clk_notify(struct clk *clk, unsigned long msg,
+			   unsigned long old_rate, unsigned long new_rate)
+{
+	struct clk_notifier *cn;
+	struct clk_notifier_data cnd;
+	int ret = NOTIFY_DONE;
+
+	cnd.clk = clk;
+	cnd.old_rate = old_rate;
+	cnd.new_rate = new_rate;
+
+	list_for_each_entry(cn, &clk_notifier_list, node) {
+		if (cn->clk == clk) {
+			ret = atomic_notifier_call_chain(&cn->notifier_head,
+							 msg, &cnd);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * _do_clk_notifier - callback function for clock change notification
+ * @clk: struct clk * to start the notifications with
+ * @msg: notifier msg - see "Clk notifier callback types"
+ * @param2: unused
+ *
+ * Notify callbacks associated with @clk that a clock change will or has
+ * occurred.  If @msg is CLK_PREPARE_RATE_CHANGE, then actually pay attention
+ * to the notifier return value.
+ */
+static int _do_clk_notifier(struct clk *clk, unsigned long msg, u8 param2)
+{
+	int ret;
+
+	ret = omap_clk_notify(clk, msg, clk->rate, clk->temp_rate);
+	if (ret && msg == CLK_PREPARE_RATE_CHANGE)
+		return ret;
+
+	if (omap_clk_has_children(clk))
+		return omap_clk_notify_downstream(clk, msg);
+	else
+		return 0;
+}
+
 /*-------------------------------------------------------------------------
  * Standard clock functions defined in include/linux/clk.h
  *-------------------------------------------------------------------------*/
@@ -440,6 +498,27 @@ void recalculate_root_clocks(void)
 			_do_propagate_rate(clkp, 0, CURRENT_RATE);
 }
 
+/**
+ * omap_clk_notify_downstream - trigger clock change notifications
+ * @clk: struct clk * to start the notifications with
+ * @msg: notifier msg - see "Clk notifier callback types"
+ *
+ * Call clock change notifiers on clocks starting with @clk and including
+ * all of @clk's downstream children clocks.  Returns NOTIFY_DONE if
+ * the notifiers ran successfully, or when msg is CLK_PREPARE_RATE_CHANGE,
+ * NOTIFY_BAD if one of the notifiers denied the change.
+ */
+int omap_clk_notify_downstream(struct clk *clk, unsigned long msg)
+{
+	if (clk == NULL || IS_ERR(clk))
+		return -EINVAL;
+
+	if (!clk->notifier_count)
+		return 0;
+
+	return omap_clk_for_each_child(clk, msg, 0, _do_clk_notifier);
+}
+
 int clk_register(struct clk *clk)
 {
 	if (clk == NULL || IS_ERR(clk))
@@ -529,6 +608,8 @@ void clk_init_cpufreq_table(struct cpufreq_frequency_table **table)
 EXPORT_SYMBOL(clk_init_cpufreq_table);
 #endif
 
+/* Clk notifier implementations */
+
 /**
  * clk_notifier_register - add a clock parameter change notifier
  * @clk: struct clk * to watch
diff --git a/arch/arm/plat-omap/include/mach/clock.h b/arch/arm/plat-omap/include/mach/clock.h
index d08f16c..2faf4c4 100644
--- a/arch/arm/plat-omap/include/mach/clock.h
+++ b/arch/arm/plat-omap/include/mach/clock.h
@@ -183,6 +183,7 @@ extern void clk_init_cpufreq_table(struct cpufreq_frequency_table **table);
 #endif
 void omap_clk_add_child(struct clk *clk, struct clk *clk2);
 void omap_clk_del_child(struct clk *clk, struct clk *clk2);
+extern int omap_clk_notify_downstream(struct clk *clk, unsigned long msg);
 
 /* Clock flags */
 #define RATE_CKCTL		(1 << 0)	/* Main fixed ratio clocks */