[RFC PATCH 4/7] clk: sunxi-ng: mux: Allow muxes to have keys

[Samuel Holland]

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 at sholland.org>
---
 drivers/clk/sunxi-ng/ccu_common.h |  1 +
 drivers/clk/sunxi-ng/ccu_mux.c    |  7 +++++++
 drivers/clk/sunxi-ng/ccu_mux.h    | 14 ++++++++++++++
 3 files changed, 22 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 785803cd7e51..fb93cea3a502 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)
@@ -188,6 +190,11 @@ 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);
 
diff --git a/drivers/clk/sunxi-ng/ccu_mux.h b/drivers/clk/sunxi-ng/ccu_mux.h
index 5aa5a6f49bd8..6ca15e43f9c8 100644
--- a/drivers/clk/sunxi-ng/ccu_mux.h
+++ b/drivers/clk/sunxi-ng/ccu_mux.h
@@ -87,6 +87,20 @@ struct ccu_mux {
 		}							\
 	}
 
+#define SUNXI_CCU_MUX_HW_WITH_KEY(_struct, _name, _parents, _reg,	\
+				  _shift, _width, _flags)		\
+	struct ccu_mux _struct = {					\
+		.mux	= _SUNXI_CCU_MUX(_shift, _width),		\
+		.common	= {						\
+			.reg		= _reg,				\
+			.features	= CCU_FEATURE_KEY_FIELD,	\
+			.hw.init	= CLK_HW_INIT_PARENTS_HW(_name,	\
+								 _parents, \
+								 &ccu_mux_ops, \
+								 _flags), \
+		}							\
+	}
+
 static inline struct ccu_mux *hw_to_ccu_mux(struct clk_hw *hw)
 {
 	struct ccu_common *common = hw_to_ccu_common(hw);
-- 
2.31.1