clk: multiplier: add explicit big endian support

Add a clock specific flag to switch register accesses to big endian, to
allow runtime configuration of big endian multiplier clocks.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk-multiplier.c

@@ -11,6 +11,22 @@
 #include <linux/of.h>
 #include <linux/slab.h>
 
+static inline u32 clk_mult_readl(struct clk_multiplier *mult)
+{
+	if (mult->flags & CLK_MULTIPLIER_BIG_ENDIAN)
+		return ioread32be(mult->reg);
+
+	return clk_readl(mult->reg);
+}
+
+static inline void clk_mult_writel(struct clk_multiplier *mult, u32 val)
+{
+	if (mult->flags & CLK_MULTIPLIER_BIG_ENDIAN)
+		iowrite32be(val, mult->reg);
+	else
+		clk_writel(val, mult->reg);
+}
+
 static unsigned long __get_mult(struct clk_multiplier *mult,
 				unsigned long rate,
 				unsigned long parent_rate)
@@ -27,7 +43,7 @@ static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw,
 	struct clk_multiplier *mult = to_clk_multiplier(hw);
 	unsigned long val;
 
-	val = clk_readl(mult->reg) >> mult->shift;
+	val = clk_mult_readl(mult) >> mult->shift;
 	val &= GENMASK(mult->width - 1, 0);
 
 	if (!val && mult->flags & CLK_MULTIPLIER_ZERO_BYPASS)
@@ -118,10 +134,10 @@ static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate,
 	else
 		__acquire(mult->lock);
 
-	val = clk_readl(mult->reg);
+	val = clk_mult_readl(mult);
 	val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift);
 	val |= factor << mult->shift;
-	clk_writel(val, mult->reg);
+	clk_mult_writel(mult, val);
 
 	if (mult->lock)
 		spin_unlock_irqrestore(mult->lock, flags);

include/linux/clk-provider.h

@@ -666,6 +666,9 @@ void clk_hw_unregister_fractional_divider(struct clk_hw *hw);
  *	leaving the parent rate unmodified.
  * CLK_MULTIPLIER_ROUND_CLOSEST - Makes the best calculated divider to be
  *	rounded to the closest integer instead of the down one.
+ * CLK_MULTIPLIER_BIG_ENDIAN - By default little endian register accesses are
+ *	used for the multiplier register.  Setting this flag makes the register
+ *	accesses big endian.
  */
 struct clk_multiplier {
 	struct clk_hw	hw;
@@ -680,6 +683,7 @@ struct clk_multiplier {
 
 #define CLK_MULTIPLIER_ZERO_BYPASS		BIT(0)
 #define CLK_MULTIPLIER_ROUND_CLOSEST	BIT(1)
+#define CLK_MULTIPLIER_BIG_ENDIAN		BIT(2)
 
 extern const struct clk_ops clk_multiplier_ops;