linux-kernel - [RFC v1] clk: core: support clocks that need to be enabled during re-parent

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Date:   Mon, 10 Jun 2019 11:44:53 +0800
From:   Weiyi Lu <weiyi.lu@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        Stephen Boyd <sboyd@...nel.org>
CC:     James Liao <jamesjj.liao@...iatek.com>,
        Fan Chen <fan.chen@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <linux-clk@...r.kernel.org>,
        <srv_heupstream@...iatek.com>, <stable@...r.kernel.org>,
        Weiyi Lu <weiyi.lu@...iatek.com>,
        Biao Huang <biao.huang@...iatek.com>
Subject: [RFC v1] clk: core: support clocks that need to be enabled during re-parent

When using property assigned-clock-parents to assign parent clocks,
core clocks might still be disabled during re-parent.
Add flag 'CLK_OPS_CORE_ENABLE' for those clocks must be enabled
during re-parent.

Signed-off-by: Weiyi Lu <weiyi.lu@...iatek.com>
---
 drivers/clk/clk.c            | 9 +++++++++
 include/linux/clk-provider.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 443711f..b2e6fe3 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1717,6 +1717,10 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core,
 		clk_core_prepare_enable(parent);
 	}
 
+	/* enable core if CLK_OPS_CORE_ENABLE is set */
+	if (core->flags & CLK_OPS_CORE_ENABLE)
+		clk_core_prepare_enable(core);
+
 	/* migrate prepare count if > 0 */
 	if (core->prepare_count) {
 		clk_core_prepare_enable(parent);
@@ -1744,6 +1748,10 @@ static void __clk_set_parent_after(struct clk_core *core,
 		clk_core_disable_unprepare(old_parent);
 	}
 
+	/* re-balance ref counting if CLK_OPS_CORE_ENABLE is set */
+	if (core->flags & CLK_OPS_CORE_ENABLE)
+		clk_core_disable_unprepare(core);
+
 	/* re-balance ref counting if CLK_OPS_PARENT_ENABLE is set */
 	if (core->flags & CLK_OPS_PARENT_ENABLE) {
 		clk_core_disable_unprepare(parent);
@@ -2973,6 +2981,7 @@ static int clk_dump_show(struct seq_file *s, void *data)
 	ENTRY(CLK_IS_CRITICAL),
 	ENTRY(CLK_OPS_PARENT_ENABLE),
 	ENTRY(CLK_DUTY_CYCLE_PARENT),
+	ENTRY(CLK_OPS_CORE_ENABLE),
 #undef ENTRY
 };
 
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index bb6118f..39a1fed 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -34,6 +34,7 @@
 #define CLK_OPS_PARENT_ENABLE	BIT(12)
 /* duty cycle call may be forwarded to the parent clock */
 #define CLK_DUTY_CYCLE_PARENT	BIT(13)
+#define CLK_OPS_CORE_ENABLE	BIT(14)	/* core need enable during re-parent */
 
 struct clk;
 struct clk_hw;
-- 
1.8.1.1.dirty