On 9/25/20 12:17 PM, Luc Michel wrote:
> A clock mux can be configured to select one of its 10 sources through
> the cm_ctl register. It also embeds yet another clock divider, composed
> of an integer part and a fractionnal part. The number of bits of each
Typo "fractional".
> part is mux dependant.
Typo "dependent"?
>
> Signed-off-by: Luc Michel <l...@lmichel.fr>
> ---
> hw/misc/bcm2835_cprman.c | 43 +++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c
> index 8df2db0fd9..75bc11939b 100644
> --- a/hw/misc/bcm2835_cprman.c
> +++ b/hw/misc/bcm2835_cprman.c
> @@ -229,19 +229,60 @@ static const TypeInfo cprman_pll_channel_info = {
> };
>
>
> /* clock mux */
>
> +static bool clock_mux_is_enabled(CprmanClockMuxState *mux)
> +{
> + return FIELD_EX32(*mux->reg_cm, CM_CLOCKx_CTL, ENABLE);
> +}
> +
> static void clock_mux_update(CprmanClockMuxState *mux)
> {
> - clock_update(mux->out, 0);
> + uint64_t freq, div;
> + uint32_t src = FIELD_EX32(*mux->reg_cm, CM_CLOCKx_CTL, SRC);
> + bool enabled = clock_mux_is_enabled(mux);
> +
> + *mux->reg_cm = FIELD_DP32(*mux->reg_cm, CM_CLOCKx_CTL, BUSY, enabled);
> +
> + if (!enabled) {
> + clock_update(mux->out, 0);
> + return;
> + }
> +
> + freq = clock_get_hz(mux->srcs[src]);
> +
> + if (mux->int_bits == 0 && mux->frac_bits == 0) {
> + clock_update_hz(mux->out, freq);
> + return;
> + }
> +
> + /*
> + * The divider has an integer and a fractional part. The size of each
> part
> + * varies with the muxes (int_bits and frac_bits). Both parts are
> + * concatenated, with the integer part always starting at bit 12.
> + */
> + div = mux->reg_cm[1] >> (R_CM_CLOCKx_DIV_FRAC_LENGTH - mux->frac_bits);
> + div &= (1 << (mux->int_bits + mux->frac_bits)) - 1;
> +
> + freq = (freq << mux->frac_bits) / div;
> +
> + clock_update_hz(mux->out, freq);
> }
>
> static void clock_mux_src_update(void *opaque)
> {
> CprmanClockMuxState **backref = opaque;
> CprmanClockMuxState *s = *backref;
> + CprmanClockMuxSource src = backref - s->backref;
> + uint32_t current_src;
> +
> + current_src = FIELD_EX32(*s->reg_cm, CM_CLOCKx_CTL, SRC);
> +
> + if (current_src != src) {
> + return;
> + }
>
> clock_mux_update(s);
> }
>
> static void clock_mux_init(Object *obj)
>
