| Message ID | 20200925101731.2159827-9-luc@lmichel.fr |
|---|---|
| State | Superseded |
| Headers | show |
| Series | raspi: add the bcm2835 cprman clock manager | expand |
On 9/25/20 12:17 PM, Luc Michel wrote: > A PLL channel is able to further divide the generated PLL frequency. The You can move the 'The' to the next line =) > divider is given in the ctrl_a2w register. Some channels have a s/a/an/ > additional fixed divider which is always applied to the signal. > > Signed-off-by: Luc Michel <luc@lmichel.fr> > --- > hw/misc/bcm2835_cprman.c | 33 ++++++++++++++++++++++++++++++++- > 1 file changed, 32 insertions(+), 1 deletion(-) > > diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c > index 2c70a3f317..e644aeb2b5 100644 > --- a/hw/misc/bcm2835_cprman.c > +++ b/hw/misc/bcm2835_cprman.c > @@ -132,13 +132,44 @@ static const TypeInfo cprman_pll_info = { > }; > > > /* PLL channel */ > > +static bool pll_channel_is_enabled(CprmanPLLChannelState *channel) > +{ > + /* > + * XXX I'm not sure of the purpose of the LOAD field. The Linux driver does > + * not set it when enabling the channel, but does clear it when disabling > + * it. Cc'ed firmware developers who might have a clue. > + */ > + return !FIELD_EX32(*channel->reg_a2w_ctrl, A2W_PLLx_CHANNELy, DISABLE) > + && !(*channel->reg_cm & channel->hold_mask); > +} > + > static void pll_channel_update(CprmanPLLChannelState *channel) > { > - clock_update(channel->out, 0); > + uint64_t freq, div; > + > + if (!pll_channel_is_enabled(channel)) { > + clock_update(channel->out, 0); > + return; > + } > + > + div = FIELD_EX32(*channel->reg_a2w_ctrl, A2W_PLLx_CHANNELy, DIV); > + > + if (!div) { > + /* > + * It seems that when the divider value is 0, it is considered as > + * being maximum by the hardware (see the Linux driver). > + */ > + div = R_A2W_PLLx_CHANNELy_DIV_MASK; > + } > + > + /* Some channels have an additional fixed divider */ > + freq = clock_get_hz(channel->pll_in) / (div * channel->fixed_divider); > + > + clock_update_hz(channel->out, freq); > } > > /* Update a PLL and all its channels */ > static void pll_update_all_channels(BCM2835CprmanState *s, > CprmanPLLState *pll) >
diff --git a/hw/misc/bcm2835_cprman.c b/hw/misc/bcm2835_cprman.c index 2c70a3f317..e644aeb2b5 100644 --- a/hw/misc/bcm2835_cprman.c +++ b/hw/misc/bcm2835_cprman.c @@ -132,13 +132,44 @@ static const TypeInfo cprman_pll_info = { }; /* PLL channel */ +static bool pll_channel_is_enabled(CprmanPLLChannelState *channel) +{ + /* + * XXX I'm not sure of the purpose of the LOAD field. The Linux driver does + * not set it when enabling the channel, but does clear it when disabling + * it. + */ + return !FIELD_EX32(*channel->reg_a2w_ctrl, A2W_PLLx_CHANNELy, DISABLE) + && !(*channel->reg_cm & channel->hold_mask); +} + static void pll_channel_update(CprmanPLLChannelState *channel) { - clock_update(channel->out, 0); + uint64_t freq, div; + + if (!pll_channel_is_enabled(channel)) { + clock_update(channel->out, 0); + return; + } + + div = FIELD_EX32(*channel->reg_a2w_ctrl, A2W_PLLx_CHANNELy, DIV); + + if (!div) { + /* + * It seems that when the divider value is 0, it is considered as + * being maximum by the hardware (see the Linux driver). + */ + div = R_A2W_PLLx_CHANNELy_DIV_MASK; + } + + /* Some channels have an additional fixed divider */ + freq = clock_get_hz(channel->pll_in) / (div * channel->fixed_divider); + + clock_update_hz(channel->out, freq); } /* Update a PLL and all its channels */ static void pll_update_all_channels(BCM2835CprmanState *s, CprmanPLLState *pll)
A PLL channel is able to further divide the generated PLL frequency. The divider is given in the ctrl_a2w register. Some channels have a additional fixed divider which is always applied to the signal. Signed-off-by: Luc Michel <luc@lmichel.fr> --- hw/misc/bcm2835_cprman.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-)