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SubjectRe: [PATCH 1/3] clk: mux: Add regmap support for simple mux
On Thu, May 28, 2015 at 08:41:46PM +0200, Matthias Brugger wrote:
> Some devices like SoCs from Mediatek need to use the clock muxes
> through a regmap interface.
> This patch adds regmap support for simple the simple multiplexer
> clock code.
>
> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> ---
> drivers/clk/clk-mux.c | 103 ++++++++++++++++++++++++++++++++++++++-----
> include/linux/clk-provider.h | 40 +++++++++++++++++
> 2 files changed, 132 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
> index 1fa2a8d..c7c692a 100644
> --- a/drivers/clk/clk-mux.c
> +++ b/drivers/clk/clk-mux.c
> @@ -29,6 +29,26 @@
>
> #define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
>
> +static void clk_mux_writel(struct clk_mux *mux, u32 val)
> +{
> + if (mux->flags && CLK_MUX_USE_REGMAP)
> + regmap_write(mux->regmap, mux->offset, val);
> + else
> + clk_writel(val, mux->reg);
> +}
> +
> +static u32 clk_mux_readl(struct clk_mux *mux)
> +{
> + u32 val;
> +
> + if (mux->flags && CLK_MUX_USE_REGMAP)
> + regmap_read(mux->regmap, mux->offset, &val);
> + else
> + val = clk_readl(mux->reg);
> +
> + return val;
> +}
> +
> static u8 clk_mux_get_parent(struct clk_hw *hw)
> {
> struct clk_mux *mux = to_clk_mux(hw);
> @@ -42,7 +62,10 @@ static u8 clk_mux_get_parent(struct clk_hw *hw)
> * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so
> * val = 0x4 really means "bit 2, index starts at bit 0"
> */
> - val = clk_readl(mux->reg) >> mux->shift;
> +
> + val = clk_mux_readl(mux);
> +
> + val >>= mux->shift;
> val &= mux->mask;
>
> if (mux->table) {
> @@ -89,11 +112,11 @@ static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
> if (mux->flags & CLK_MUX_HIWORD_MASK) {
> val = mux->mask << (mux->shift + 16);
> } else {
> - val = clk_readl(mux->reg);
> + val = clk_mux_readl(mux);
> val &= ~(mux->mask << mux->shift);
> }
> val |= index << mux->shift;
> - clk_writel(val, mux->reg);
> + clk_mux_writel(mux, val);

With regmap the register lock is inside the regmap, you must hold it
during read/modify/write operations which means you have to use
regmap_update_bits rather than regmap_read followed by regmap_write.

Sascha

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