sh: clkfwk: Use shared sh_clk_div_enable/disable().

This introduces a new flag for clocks that need to have their divisor
ratio set back to their initial mask at disable time to prevent
interactivity problems with the clock stop bit (presently div6 only).
With this in place it's possible to handle the corner case on top of the
div4 op without any particular need for leaving things split out.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/sh/clk/cpg.c

@@ -14,6 +14,8 @@
 #include <linux/io.h>
 #include <linux/sh_clk.h>
 
+#define CPG_CKSTP_BIT	BIT(8)
+
 static unsigned int sh_clk_read(struct clk *clk)
 {
 	if (clk->flags & CLK_ENABLE_REG_8BIT)
@@ -122,6 +124,30 @@ static int sh_clk_div_set_rate(struct clk *clk, unsigned long rate)
 	return 0;
 }
 
+static int sh_clk_div_enable(struct clk *clk)
+{
+	sh_clk_write(sh_clk_read(clk) & ~CPG_CKSTP_BIT, clk);
+	return 0;
+}
+
+static void sh_clk_div_disable(struct clk *clk)
+{
+	unsigned int val;
+
+	val = sh_clk_read(clk);
+	val |= CPG_CKSTP_BIT;
+
+	/*
+	 * div6 clocks require the divisor field to be non-zero or the
+	 * above CKSTP toggle silently fails. Ensure that the divisor
+	 * array is reset to its initial state on disable.
+	 */
+	if (clk->flags & CLK_MASK_DIV_ON_DISABLE)
+		val |= clk->div_mask;
+
+	sh_clk_write(val, clk);
+}
+
 /*
  * div6 support
  */
@@ -174,44 +200,20 @@ static int sh_clk_div6_set_parent(struct clk *clk, struct clk *parent)
 	return 0;
 }
 
-static int sh_clk_div6_enable(struct clk *clk)
-{
-	unsigned long value;
-	int ret;
-
-	ret = sh_clk_div_set_rate(clk, clk->rate);
-	if (ret == 0) {
-		value = sh_clk_read(clk);
-		value &= ~0x100; /* clear stop bit to enable clock */
-		sh_clk_write(value, clk);
-	}
-	return ret;
-}
-
-static void sh_clk_div6_disable(struct clk *clk)
-{
-	unsigned long value;
-
-	value = sh_clk_read(clk);
-	value |= 0x100; /* stop clock */
-	value |= clk->div_mask; /* VDIV bits must be non-zero, overwrite divider */
-	sh_clk_write(value, clk);
-}
-
 static struct sh_clk_ops sh_clk_div6_clk_ops = {
 	.recalc		= sh_clk_div_recalc,
 	.round_rate	= sh_clk_div_round_rate,
 	.set_rate	= sh_clk_div_set_rate,
-	.enable		= sh_clk_div6_enable,
-	.disable	= sh_clk_div6_disable,
+	.enable		= sh_clk_div_enable,
+	.disable	= sh_clk_div_disable,
 };
 
 static struct sh_clk_ops sh_clk_div6_reparent_clk_ops = {
 	.recalc		= sh_clk_div_recalc,
 	.round_rate	= sh_clk_div_round_rate,
 	.set_rate	= sh_clk_div_set_rate,
-	.enable		= sh_clk_div6_enable,
-	.disable	= sh_clk_div6_disable,
+	.enable		= sh_clk_div_enable,
+	.disable	= sh_clk_div_disable,
 	.set_parent	= sh_clk_div6_set_parent,
 };
 
@@ -325,17 +327,6 @@ static int sh_clk_div4_set_parent(struct clk *clk, struct clk *parent)
 	return 0;
 }
 
-static int sh_clk_div4_enable(struct clk *clk)
-{
-	sh_clk_write(sh_clk_read(clk) & ~(1 << 8), clk);
-	return 0;
-}
-
-static void sh_clk_div4_disable(struct clk *clk)
-{
-	sh_clk_write(sh_clk_read(clk) | (1 << 8), clk);
-}
-
 static struct sh_clk_ops sh_clk_div4_clk_ops = {
 	.recalc		= sh_clk_div_recalc,
 	.set_rate	= sh_clk_div_set_rate,
@@ -346,16 +337,16 @@ static struct sh_clk_ops sh_clk_div4_enable_clk_ops = {
 	.recalc		= sh_clk_div_recalc,
 	.set_rate	= sh_clk_div_set_rate,
 	.round_rate	= sh_clk_div_round_rate,
-	.enable		= sh_clk_div4_enable,
-	.disable	= sh_clk_div4_disable,
+	.enable		= sh_clk_div_enable,
+	.disable	= sh_clk_div_disable,
 };
 
 static struct sh_clk_ops sh_clk_div4_reparent_clk_ops = {
 	.recalc		= sh_clk_div_recalc,
 	.set_rate	= sh_clk_div_set_rate,
 	.round_rate	= sh_clk_div_round_rate,
-	.enable		= sh_clk_div4_enable,
-	.disable	= sh_clk_div4_disable,
+	.enable		= sh_clk_div_enable,
+	.disable	= sh_clk_div_disable,
 	.set_parent	= sh_clk_div4_set_parent,
 };
 

include/linux/sh_clk.h

@@ -69,6 +69,8 @@ struct clk {
 #define CLK_ENABLE_REG_16BIT	BIT(2)
 #define CLK_ENABLE_REG_8BIT	BIT(3)
 
+#define CLK_MASK_DIV_ON_DISABLE	BIT(4)
+
 #define CLK_ENABLE_REG_MASK	(CLK_ENABLE_REG_32BIT | \
 				 CLK_ENABLE_REG_16BIT | \
 				 CLK_ENABLE_REG_8BIT)
@@ -173,7 +175,7 @@ int sh_clk_div4_reparent_register(struct clk *clks, int nr,
 {								\
 	.enable_reg = (void __iomem *)_reg,			\
 	.enable_bit = 0, /* unused */				\
-	.flags = _flags,					\
+	.flags = _flags | CLK_MASK_DIV_ON_DISABLE,		\
 	.div_mask = SH_CLK_DIV6_MSK,				\
 	.parent_table = _parents,				\
 	.parent_num = _num_parents,				\
@@ -187,7 +189,7 @@ int sh_clk_div4_reparent_register(struct clk *clks, int nr,
 	.enable_reg	= (void __iomem *)_reg,			\
 	.enable_bit	= 0,	/* unused */			\
 	.div_mask	= SH_CLK_DIV6_MSK,			\
-	.flags		= _flags,				\
+	.flags		= _flags | CLK_MASK_DIV_ON_DISABLE,	\
 }
 
 int sh_clk_div6_register(struct clk *clks, int nr);