From 056b205316cc3dcf8a67cf813a26ff8a72bf3cb9 Mon Sep 17 00:00:00 2001 From: Soren Brinkmann Date: Tue, 2 Apr 2013 15:36:56 -0700 Subject: clk: divider: Introduce CLK_DIVIDER_ALLOW_ZERO flag Dividers which have CLK_DIVIDER_ONE_BASED set have a redundant state, being a divider value of zero. Some hardware implementations allow a zero divider which simply doesn't alter the frequency. I.e. it acts like a divide by one or bypassing the divider. This flag is used to handle such HW in the clk-divider model. Signed-off-by: Soren Brinkmann Signed-off-by: Mike Turquette --- include/linux/clk-provider.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include/linux/clk-provider.h') diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index b1675074fe7c..9fdfae74d669 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -249,9 +249,14 @@ struct clk_div_table { * CLK_DIVIDER_ONE_BASED - by default the divisor is the value read from the * register plus one. If CLK_DIVIDER_ONE_BASED is set then the divider is * the raw value read from the register, with the value of zero considered - * invalid + * invalid, unless CLK_DIVIDER_ALLOW_ZERO is set. * CLK_DIVIDER_POWER_OF_TWO - clock divisor is 2 raised to the value read from * the hardware register + * CLK_DIVIDER_ALLOW_ZERO - Allow zero divisors. For dividers which have + * CLK_DIVIDER_ONE_BASED set, it is possible to end up with a zero divisor. + * Some hardware implementations gracefully handle this case and allow a + * zero divisor by not modifying their input clock + * (divide by one / bypass). */ struct clk_divider { struct clk_hw hw; @@ -265,6 +270,7 @@ struct clk_divider { #define CLK_DIVIDER_ONE_BASED BIT(0) #define CLK_DIVIDER_POWER_OF_TWO BIT(1) +#define CLK_DIVIDER_ALLOW_ZERO BIT(2) extern const struct clk_ops clk_divider_ops; struct clk *clk_register_divider(struct device *dev, const char *name, -- cgit v1.2.3