clk: gate: add explicit big endian support

Add a clock specific flag to switch register accesses to big endian, to
allow runtime configuration of big endian gated clocks.
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk-gate.c

@@ -23,6 +23,22 @@
  * parent - fixed parent.  No clk_set_parent support
  */
 
+static inline u32 clk_gate_readl(struct clk_gate *gate)
+{
+	if (gate->flags & CLK_GATE_BIG_ENDIAN)
+		return ioread32be(gate->reg);
+
+	return clk_readl(gate->reg);
+}
+
+static inline void clk_gate_writel(struct clk_gate *gate, u32 val)
+{
+	if (gate->flags & CLK_GATE_BIG_ENDIAN)
+		iowrite32be(val, gate->reg);
+	else
+		clk_writel(val, gate->reg);
+}
+
 /*
  * It works on following logic:
  *
@@ -55,7 +71,7 @@ static void clk_gate_endisable(struct clk_hw *hw, int enable)
 		if (set)
 			reg |= BIT(gate->bit_idx);
 	} else {
-		reg = clk_readl(gate->reg);
+		reg = clk_gate_readl(gate);
 
 		if (set)
 			reg |= BIT(gate->bit_idx);
@@ -63,7 +79,7 @@ static void clk_gate_endisable(struct clk_hw *hw, int enable)
 			reg &= ~BIT(gate->bit_idx);
 	}
 
-	clk_writel(reg, gate->reg);
+	clk_gate_writel(gate, reg);
 
 	if (gate->lock)
 		spin_unlock_irqrestore(gate->lock, flags);
@@ -88,7 +104,7 @@ int clk_gate_is_enabled(struct clk_hw *hw)
 	u32 reg;
 	struct clk_gate *gate = to_clk_gate(hw);
 
-	reg = clk_readl(gate->reg);
+	reg = clk_gate_readl(gate);
 
 	/* if a set bit disables this clk, flip it before masking */
 	if (gate->flags & CLK_GATE_SET_TO_DISABLE)

include/linux/clk-provider.h

@@ -349,6 +349,9 @@ void of_fixed_clk_setup(struct device_node *np);
  *	of this register, and mask of gate bits are in higher 16-bit of this
  *	register.  While setting the gate bits, higher 16-bit should also be
  *	updated to indicate changing gate bits.
+ * CLK_GATE_BIG_ENDIAN - by default little endian register accesses are used for
+ *	the gate register.  Setting this flag makes the register accesses big
+ *	endian.
  */
 struct clk_gate {
 	struct clk_hw hw;
@@ -362,6 +365,7 @@ struct clk_gate {
 
 #define CLK_GATE_SET_TO_DISABLE		BIT(0)
 #define CLK_GATE_HIWORD_MASK		BIT(1)
+#define CLK_GATE_BIG_ENDIAN		BIT(2)
 
 extern const struct clk_ops clk_gate_ops;
 struct clk *clk_register_gate(struct device *dev, const char *name,