From 957458111280e7772cffc1ccbac75a5270e9267f Mon Sep 17 00:00:00 2001 From: Luc Michel Date: Sat, 10 Oct 2020 15:57:53 +0200 Subject: [PATCH] hw/misc/bcm2835_cprman: implement PLL channels behaviour MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit A PLL channel is able to further divide the generated PLL frequency. The divider is given in the CTRL_A2W register. Some channels have an additional fixed divider which is always applied to the signal. Tested-by: Philippe Mathieu-Daudé Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Luc Michel Tested-by: Guenter Roeck Signed-off-by: Peter Maydell --- 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 12fa78181b..71c1d7b9e7 100644 --- a/hw/misc/bcm2835_cprman.c +++ b/hw/misc/bcm2835_cprman.c @@ -134,9 +134,40 @@ 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 */ -- 2.11.4.GIT