[PATCH 3/9] clk: fractional-divider: add CLK_FRAC_DIVIDER_ZERO_BASED flag support

Dong Aisheng
2017-05-15T13:59:17Z

Adding CLK_FRAC_DIVIDER_ZERO_BASED flag to indicate the numerator and
denominator value in register are start from 0.

This can be used to support frac dividers like below:
Divider output clock = Divider input clock x [(frac +1) / (div +1)]
where frac/div in register is:
000b - Divide by 1.
001b - Divide by 2.
010b - Divide by 3.

Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
drivers/clk/clk-fractional-divider.c | 10 ++++++++++
include/linux/clk-provider.h | 7 +++++++
2 files changed, 17 insertions(+)

diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c
index aab9046..455bec5 100644
--- a/drivers/clk/clk-fractional-divider.c
+++ b/drivers/clk/clk-fractional-divider.c
@@ -40,6 +40,11 @@ static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
m = (val & fd->mmask) >> fd->mshift;
n = (val & fd->nmask) >> fd->nshift;

+ if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
+ m++;
+ n++;
+ }
+
if (!n || !m)
return parent_rate;

@@ -91,6 +96,11 @@ static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0),
&m, &n);

+ if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
+ m--;
+ n--;
+ }
+
if (fd->lock)
spin_lock_irqsave(fd->lock, flags);
else
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index a6efbb9..4466cae 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -557,6 +557,11 @@ void clk_hw_unregister_fixed_factor(struct clk_hw *hw);
* @lock: register lock
*
* Clock with adjustable fractional divider affecting its output frequency.
+ *
+ * Flags:
+ * CLK_FRAC_DIVIDER_ZERO_BASED - by default the divisor is the value read
+ * from the register. If CLK_FRAC_DIVIDER_ZERO_BASED is set then the
+ * divider is the raw value read from the register plus one.
*/
struct clk_fractional_divider {
struct clk_hw hw;
@@ -573,6 +578,8 @@ 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)
+
extern const struct clk_ops clk_fractional_divider_ops;
struct clk *clk_register_fractional_divider(struct device *dev,
const char *name, const char *parent_name, unsigned long flags,
--
2.7.4