clk: Add generic sync_state callback for disabling unused clocks

There are unused clocks that need to remain untouched by clk_disable_unused,
and most likely could be disabled later on sync_state. So provide a generic
sync_state callback for the clock providers that register such clocks.
Then, use the same mechanism as clk_disable_unused from that generic
callback, but pass the device to make sure only the clocks belonging to
the current clock provider get disabled, if unused. Also, during the
default clk_disable_unused, if the driver that registered the clock has
the generic clk_sync_state_disable_unused callback set for sync_state,
skip disabling its clocks.
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221227204528.1899863-1-abel.vesa@linaro.org

drivers/clk/clk.c

@@ -1302,14 +1302,26 @@ static void clk_core_disable_unprepare(struct clk_core *core)
 	clk_core_unprepare_lock(core);
 }
 
-static void __init clk_unprepare_unused_subtree(struct clk_core *core)
+static void clk_unprepare_unused_subtree(struct clk_core *core,
+						struct device *dev)
 {
+	bool from_sync_state = !!dev;
 	struct clk_core *child;
 
 	lockdep_assert_held(&prepare_lock);
 
 	hlist_for_each_entry(child, &core->children, child_node)
-		clk_unprepare_unused_subtree(child);
+		clk_unprepare_unused_subtree(child, dev);
+
+	if (from_sync_state && core->dev != dev)
+		return;
+
+	/*
+	 * clock will be unprepared on sync_state,
+	 * so leave as is for now
+	 */
+	if (!from_sync_state && dev_has_sync_state(core->dev))
+		return;
 
 	if (core->prepare_count)
 		return;
@@ -1332,15 +1344,27 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
 	clk_pm_runtime_put(core);
 }
 
-static void __init clk_disable_unused_subtree(struct clk_core *core)
+static void clk_disable_unused_subtree(struct clk_core *core,
+					struct device *dev)
 {
+	bool from_sync_state = !!dev;
 	struct clk_core *child;
 	unsigned long flags;
 
 	lockdep_assert_held(&prepare_lock);
 
 	hlist_for_each_entry(child, &core->children, child_node)
-		clk_disable_unused_subtree(child);
+		clk_disable_unused_subtree(child, dev);
+
+	if (from_sync_state && core->dev != dev)
+		return;
+
+	/*
+	 * clock will be disabled on sync_state,
+	 * so leave as is for now
+	 */
+	if (!from_sync_state && dev_has_sync_state(core->dev))
+		return;
 
 	if (core->flags & CLK_OPS_PARENT_ENABLE)
 		clk_core_prepare_enable(core->parent);
@@ -1378,7 +1402,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
 		clk_core_disable_unprepare(core->parent);
 }
 
-static bool clk_ignore_unused __initdata;
+static bool clk_ignore_unused;
 static int __init clk_ignore_unused_setup(char *__unused)
 {
 	clk_ignore_unused = true;
@@ -1386,35 +1410,46 @@ static int __init clk_ignore_unused_setup(char *__unused)
 }
 __setup("clk_ignore_unused", clk_ignore_unused_setup);
 
-static int __init clk_disable_unused(void)
+static void __clk_disable_unused(struct device *dev)
 {
 	struct clk_core *core;
 
 	if (clk_ignore_unused) {
 		pr_warn("clk: Not disabling unused clocks\n");
-		return 0;
+		return;
 	}
 
 	clk_prepare_lock();
 
 	hlist_for_each_entry(core, &clk_root_list, child_node)
-		clk_disable_unused_subtree(core);
+		clk_disable_unused_subtree(core, dev);
 
 	hlist_for_each_entry(core, &clk_orphan_list, child_node)
-		clk_disable_unused_subtree(core);
+		clk_disable_unused_subtree(core, dev);
 
 	hlist_for_each_entry(core, &clk_root_list, child_node)
-		clk_unprepare_unused_subtree(core);
+		clk_unprepare_unused_subtree(core, dev);
 
 	hlist_for_each_entry(core, &clk_orphan_list, child_node)
-		clk_unprepare_unused_subtree(core);
+		clk_unprepare_unused_subtree(core, dev);
 
 	clk_prepare_unlock();
+}
+
+static int __init clk_disable_unused(void)
+{
+	__clk_disable_unused(NULL);
 
 	return 0;
 }
 late_initcall_sync(clk_disable_unused);
 
+void clk_sync_state_disable_unused(struct device *dev)
+{
+	__clk_disable_unused(dev);
+}
+EXPORT_SYMBOL_GPL(clk_sync_state_disable_unused);
+
 static int clk_core_determine_round_nolock(struct clk_core *core,
 					   struct clk_rate_request *req)
 {

include/linux/clk-provider.h

@@ -720,6 +720,7 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock);
+void clk_sync_state_disable_unused(struct device *dev);
 /**
  * clk_register_divider - register a divider clock with the clock framework
  * @dev: device registering this clock