Quoting Heiko Stübner (2013-06-11 04:29:32)
> SoCs like the Rockchip Cortex-A9 ones contain divider some clocks
> that use the regular mechanisms for storage but allow only even
> dividers and 1 to be used.
>
> Therefore add a flag that lets _is_valid_div limit the valid dividers
> to these values. _get_maxdiv is also adapted to return even values
> for the CLK_DIVIDER_ONE_BASED case.
>
> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> ---
> drivers/clk/clk-divider.c | 14 ++++++++++++--
> include/linux/clk-provider.h | 2 ++
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index ce5cfe9..bdee7cf 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -45,8 +45,16 @@ static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
>
> static unsigned int _get_maxdiv(struct clk_divider *divider)
> {
> - if (divider->flags & CLK_DIVIDER_ONE_BASED)
> - return div_mask(divider);
> + if (divider->flags & CLK_DIVIDER_ONE_BASED) {
> + unsigned int div = div_mask(divider);
> +
> + /* decrease to even number */
> + if (divider->flags & CLK_DIVIDER_EVEN)
> + div--;
> +
> + return div;
> + }
> +
> if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
> return 1 << div_mask(divider);
> if (divider->table)
> @@ -141,6 +149,8 @@ static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
> return is_power_of_2(div);
> if (divider->table)
> return _is_valid_table_div(divider->table, div);
> + if (divider->flags & CLK_DIVIDER_EVEN && div != 1 && (div % 2) != 0)
Is it correct to check for 'div != 1' here? Wouldn't that check only be
valid in the presence of CLK_DIVIDER_ONE_BASED?
Maybe something like this would be more correct:
if (divider->flags & CLK_DIVIDER_EVEN && (div % 2) != 0) {
if (divider->flags & CLK_DIVIDER_ONE_BASED && div == 1)
return true;
return false;
}
Regards,
Mike
> + return false;
> return true;
> }
>
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 1ec14a7..bd52e52 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -266,6 +266,7 @@ struct clk_div_table {
> * of this register, and mask of divider bits are in higher 16-bit of this
> * register. While setting the divider bits, higher 16-bit should also be
> * updated to indicate changing divider bits.
> + * CLK_DIVIDER_EVEN - only allow even divider values
> */
> struct clk_divider {
> struct clk_hw hw;
> @@ -281,6 +282,7 @@ struct clk_divider {
> #define CLK_DIVIDER_POWER_OF_TWO BIT(1)
> #define CLK_DIVIDER_ALLOW_ZERO BIT(2)
> #define CLK_DIVIDER_HIWORD_MASK BIT(3)
> +#define CLK_DIVIDER_EVEN BIT(4)
>
> extern const struct clk_ops clk_divider_ops;
> struct clk *clk_register_divider(struct device *dev, const char *name,
> --
> 1.7.2.3
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