clk: 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 divider clocks.

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

drivers/clk/clk-divider.c

@@ -25,6 +25,22 @@
  * parent - fixed parent.  No clk_set_parent support
  */
 
+static inline u32 clk_div_readl(struct clk_divider *divider)
+{
+	if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
+		return ioread32be(divider->reg);
+
+	return clk_readl(divider->reg);
+}
+
+static inline void clk_div_writel(struct clk_divider *divider, u32 val)
+{
+	if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
+		iowrite32be(val, divider->reg);
+	else
+		clk_writel(val, divider->reg);
+}
+
 static unsigned int _get_table_maxdiv(const struct clk_div_table *table,
 				      u8 width)
 {
@@ -135,7 +151,7 @@ static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
 	struct clk_divider *divider = to_clk_divider(hw);
 	unsigned int val;
 
-	val = clk_readl(divider->reg) >> divider->shift;
+	val = clk_div_readl(divider) >> divider->shift;
 	val &= clk_div_mask(divider->width);
 
 	return divider_recalc_rate(hw, parent_rate, val, divider->table,
@@ -370,7 +386,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 	if (divider->flags & CLK_DIVIDER_READ_ONLY) {
 		u32 val;
 
-		val = clk_readl(divider->reg) >> divider->shift;
+		val = clk_div_readl(divider) >> divider->shift;
 		val &= clk_div_mask(divider->width);
 
 		return divider_ro_round_rate(hw, rate, prate, divider->table,
@@ -420,11 +436,11 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
 		val = clk_div_mask(divider->width) << (divider->shift + 16);
 	} else {
-		val = clk_readl(divider->reg);
+		val = clk_div_readl(divider);
 		val &= ~(clk_div_mask(divider->width) << divider->shift);
 	}
 	val |= (u32)value << divider->shift;
-	clk_writel(val, divider->reg);
+	clk_div_writel(divider, val);
 
 	if (divider->lock)
 		spin_unlock_irqrestore(divider->lock, flags);

include/linux/clk-provider.h

@@ -417,6 +417,9 @@ struct clk_div_table {
  * CLK_DIVIDER_MAX_AT_ZERO - For dividers which are like CLK_DIVIDER_ONE_BASED
  *	except when the value read from the register is zero, the divisor is
  *	2^width of the field.
+ * CLK_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_divider {
 	struct clk_hw	hw;
@@ -438,6 +441,7 @@ struct clk_divider {
 #define CLK_DIVIDER_ROUND_CLOSEST	BIT(4)
 #define CLK_DIVIDER_READ_ONLY		BIT(5)
 #define CLK_DIVIDER_MAX_AT_ZERO		BIT(6)
+#define CLK_DIVIDER_BIG_ENDIAN		BIT(7)
 
 extern const struct clk_ops clk_divider_ops;
 extern const struct clk_ops clk_divider_ro_ops;