| Message ID | 20201005195612.1999165-12-luc@lmichel.fr |
|---|---|
| State | New |
| Headers | show |
| Series | raspi: add the bcm2835 cprman clock manager | expand |
On 10/5/20 9:56 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 fractional part. The number of bits of each > part is mux dependent. > > Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > Signed-off-by: Luc Michel <luc@lmichel.fr> > --- > hw/misc/bcm2835_cprman.c | 44 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 43 insertions(+), 1 deletion(-) > > diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c > index a470ce2026..7d59423367 100644 > --- a/hw/misc/bcm2835_cprman.c > +++ b/hw/misc/bcm2835_cprman.c > @@ -229,19 +229,61 @@ 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; > + uint32_t div, 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; I understand the description as: 0 [ 12-bit ][ 12-bit ][ reserved... ] CM_CLOCKx_DIV [ FRAC ][ INT ][ ] [ <frac>][<int> ][ ] ^^^^^^^^^^^^^ What about: div = extract32(mux->reg_cm[1], R_CM_CLOCKx_DIV_FRAC_LENGTH - mux->frac_bits, mux->frac_bits, mux->int_bits); Also consider adding the register visual representation if it is correct. > + > + if (!div) { > + clock_update(mux->out, 0); > + } > + > + freq = muldiv64(freq, 1 << 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; > + > + if (FIELD_EX32(*s->reg_cm, CM_CLOCKx_CTL, SRC) != src) { > + return; > + } > > clock_mux_update(s); > } > > static void clock_mux_init(Object *obj) >
On 11:04 Tue 06 Oct , Philippe Mathieu-Daudé wrote: > On 10/5/20 9:56 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 fractional part. The number of bits of each > > part is mux dependent. > > > > Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > > Signed-off-by: Luc Michel <luc@lmichel.fr> > > --- > > hw/misc/bcm2835_cprman.c | 44 +++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 43 insertions(+), 1 deletion(-) > > > > diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c > > index a470ce2026..7d59423367 100644 > > --- a/hw/misc/bcm2835_cprman.c > > +++ b/hw/misc/bcm2835_cprman.c > > @@ -229,19 +229,61 @@ 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; > > + uint32_t div, 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; > > I understand the description as: > > 0 > [ 12-bit ][ 12-bit ][ reserved... ] > CM_CLOCKx_DIV [ FRAC ][ INT ][ ] > [ <frac>][<int> ][ ] > ^^^^^^^^^^^^^ Yes, this is correct :) > > What about: > > div = extract32(mux->reg_cm[1], > R_CM_CLOCKx_DIV_FRAC_LENGTH - mux->frac_bits, > mux->frac_bits, mux->int_bits); Yes good idea, with s/,/+/ here -------^ > > Also consider adding the register visual representation if it is > correct. Sure, I'll add a visual representation for more clarity. Thanks!
diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c index a470ce2026..7d59423367 100644 --- a/hw/misc/bcm2835_cprman.c +++ b/hw/misc/bcm2835_cprman.c @@ -229,19 +229,61 @@ 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; + uint32_t div, 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; + + if (!div) { + clock_update(mux->out, 0); + } + + freq = muldiv64(freq, 1 << 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; + + if (FIELD_EX32(*s->reg_cm, CM_CLOCKx_CTL, SRC) != src) { + return; + } clock_mux_update(s); } static void clock_mux_init(Object *obj)