clk: fractional-divider: add explicit big endian support

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

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

drivers/clk/clk-fractional-divider.c

@@ -13,6 +13,22 @@
 #include <linux/slab.h>
 #include <linux/rational.h>
 
+static inline u32 clk_fd_readl(struct clk_fractional_divider *fd)
+{
+	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
+		return ioread32be(fd->reg);
+
+	return clk_readl(fd->reg);
+}
+
+static inline void clk_fd_writel(struct clk_fractional_divider *fd, u32 val)
+{
+	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
+		iowrite32be(val, fd->reg);
+	else
+		clk_writel(val, fd->reg);
+}
+
 static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
 					unsigned long parent_rate)
 {
@@ -27,7 +43,7 @@ static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
 	else
 		__acquire(fd->lock);
 
-	val = clk_readl(fd->reg);
+	val = clk_fd_readl(fd);
 
 	if (fd->lock)
 		spin_unlock_irqrestore(fd->lock, flags);
@@ -115,10 +131,10 @@ static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
 	else
 		__acquire(fd->lock);
 
-	val = clk_readl(fd->reg);
+	val = clk_fd_readl(fd);
 	val &= ~(fd->mmask | fd->nmask);
 	val |= (m << fd->mshift) | (n << fd->nshift);
-	clk_writel(val, fd->reg);
+	clk_fd_writel(fd, val);
 
 	if (fd->lock)
 		spin_unlock_irqrestore(fd->lock, flags);

include/linux/clk-provider.h

@@ -606,6 +606,9 @@ void clk_hw_unregister_fixed_factor(struct clk_hw *hw);
  *	is the value read from the register. If CLK_FRAC_DIVIDER_ZERO_BASED
  *	is set then the numerator and denominator are both the value read
  *	plus one.
+ * CLK_FRAC_DIVIDER_BIG_ENDIAN - By default little endian register accesses are
+ *	used for the divider register.  Setting this flag makes the register
+ *	accesses big endian.
  */
 struct clk_fractional_divider {
 	struct clk_hw	hw;
@@ -626,6 +629,7 @@ struct clk_fractional_divider {
 #define to_clk_fd(_hw) container_of(_hw, struct clk_fractional_divider, hw)
 
 #define CLK_FRAC_DIVIDER_ZERO_BASED		BIT(0)
+#define CLK_FRAC_DIVIDER_BIG_ENDIAN		BIT(1)
 
 extern const struct clk_ops clk_fractional_divider_ops;
 struct clk *clk_register_fractional_divider(struct device *dev,