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 <f4...@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
Signed-off-by: Luc Michel <l...@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 12fa78181b..71c1d7b9e7 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)
--
2.28.0
