linux-kernel - [PATCH v3 4/6] clk: sunxi-ng: mux: Allow muxes to have keys

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Date:   Wed,  2 Feb 2022 20:17:34 -0600
From:   Samuel Holland <samuel@...lland.org>
To:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        linux-sunxi@...ts.linux.dev
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Michael Turquette <mturquette@...libre.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, Stephen Boyd <sboyd@...nel.org>,
        Samuel Holland <samuel@...lland.org>
Subject: [PATCH v3 4/6] clk: sunxi-ng: mux: Allow muxes to have keys

The muxes in the RTC can only be updated when setting a key field to a
specific value. Add a feature flag to denote muxes with this property.

Since so far the key value is always the same, it does not need to be
provided separately for each mux.

Signed-off-by: Samuel Holland <samuel@...lland.org>
---

Changes in v3:
 - Drop the SUNXI_CCU_MUX_HW_WITH_KEY macro, since it is no longer used.

 drivers/clk/sunxi-ng/ccu_common.h | 1 +
 drivers/clk/sunxi-ng/ccu_mux.c    | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h
index 98a1834b58bb..fbf16c6b896d 100644
--- a/drivers/clk/sunxi-ng/ccu_common.h
+++ b/drivers/clk/sunxi-ng/ccu_common.h
@@ -17,6 +17,7 @@
 #define CCU_FEATURE_LOCK_REG		BIT(5)
 #define CCU_FEATURE_MMC_TIMING_SWITCH	BIT(6)
 #define CCU_FEATURE_SIGMA_DELTA_MOD	BIT(7)
+#define CCU_FEATURE_KEY_FIELD		BIT(8)
 
 /* MMC timing mode switch bit */
 #define CCU_MMC_NEW_TIMING_MODE		BIT(30)
diff --git a/drivers/clk/sunxi-ng/ccu_mux.c b/drivers/clk/sunxi-ng/ccu_mux.c
index 2306a1cd83e4..1d557e323169 100644
--- a/drivers/clk/sunxi-ng/ccu_mux.c
+++ b/drivers/clk/sunxi-ng/ccu_mux.c
@@ -12,6 +12,8 @@
 #include "ccu_gate.h"
 #include "ccu_mux.h"
 
+#define CCU_MUX_KEY_VALUE		0x16aa0000
+
 static u16 ccu_mux_get_prediv(struct ccu_common *common,
 			      struct ccu_mux_internal *cm,
 			      int parent_index)
@@ -191,6 +193,11 @@ int ccu_mux_helper_set_parent(struct ccu_common *common,
 	spin_lock_irqsave(common->lock, flags);
 
 	reg = readl(common->base + common->reg);
+
+	/* The key field always reads as zero. */
+	if (common->features & CCU_FEATURE_KEY_FIELD)
+		reg |= CCU_MUX_KEY_VALUE;
+
 	reg &= ~GENMASK(cm->width + cm->shift - 1, cm->shift);
 	writel(reg | (index << cm->shift), common->base + common->reg);
 
-- 
2.33.1