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clk: fractional-divider: add CLK_FRAC_DIVIDER_ZERO_BASED flag support 

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>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
This commit is contained in:
A.s. Dong 2018-11-14 13:01:39 +00:00 committed by Stephen Boyd
parent 4046807942
commit e983da27f7
2 changed files with 18 additions and 0 deletions
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10
drivers/clk/clk-fractional-divider.c
View File

@ -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;
@ -103,6 +108,11 @@ 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

8
include/linux/clk-provider.h
View File

@ -601,6 +601,12 @@ 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 numerator and denominator
* 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.
*/
struct clk_fractional_divider {
struct clk_hw hw;
@ -620,6 +626,8 @@ 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,