Re: [PATCH v5 4/5] clk: spacemit: k1: Add TWSI8 bus and function clocks

Haylen Chu
2025-03-07T06:31:07Z

On Thu, Mar 06, 2025 at 05:57:50PM +0000, Haylen Chu wrote:
> The control register for TWSI8 clocks, APBC_TWSI8_CLK_RST, contains mux
> selection bits, reset assertion bit and enable bits for function and bus
> clocks. It has a quirk that reading always results in zero.
>
> As a workaround, let's hardcode the mux value as zero to select
> pll1_d78_31p5 as parent and treat twsi8_clk as a gate, whose enable mask
> is combined from the real bus and function clocks to avoid the
> write-only register being shared between two clk_hws, in which case
> updates of one clk_hw zero the other's bits.
>
> With a 1:1 factor serving as placeholder for the bus clock, the I2C-8
> controller could be brought up, which is essential for boards attaching
> power-management chips to it.
>
> Signed-off-by: Haylen Chu <heylenay@4d2.org>
> ---
> drivers/clk/spacemit/ccu-k1.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
> index 5974a0a1b5f6..44db48ae7131 100644
> --- a/drivers/clk/spacemit/ccu-k1.c
> +++ b/drivers/clk/spacemit/ccu-k1.c
> @@ -558,6 +558,10 @@ static CCU_MUX_GATE_DEFINE(twsi7_clk, twsi_parents,
> APBC_TWSI7_CLK_RST,
> 4, 3, BIT(1),
> 0);
> +static CCU_GATE_DEFINE(twsi8_clk, CCU_PARENT_HW(pll1_d78_31p5),
> + APBC_TWSI8_CLK_RST,
> + BIT(1) | BIT(0),
> + 0);
>
> static const struct clk_parent_data timer_parents[] = {
> CCU_PARENT_HW(pll1_d192_12p8),
> @@ -795,6 +799,8 @@ static CCU_GATE_DEFINE(twsi7_bus_clk, CCU_PARENT_HW(apb_clk),
> APBC_TWSI7_CLK_RST,
> BIT(0),
> 0);
> +static CCU_FACTOR_DEFINE(twsi8_bus_clk, CCU_PARENT_HW(apb_clk),
> + 1, 1);
>
> static CCU_GATE_DEFINE(timers1_bus_clk, CCU_PARENT_HW(apb_clk),
> APBC_TIMERS1_CLK_RST,
> --
> 2.48.1
>

Oops, I don't split out the twsi8-related definitions completely from
PATCH 3, causing building errors with only PATCH 3 applied. Will fix it
in the next version.

Best regards,
Haylen Chu