qemu /
qemu /
6f86885a74584f069db95bd6043d9497388808b4 ppc/pnv: Wire up pca9552 GPIO pins for PCIe hotplug power control
For power10-rainier, a pca9552 device is used for PCIe slot hotplug
power control by the Power Hypervisor code. The code expects that
some time after it enables power to a PCIe slot by asserting one of
the pca9552 GPIO pins 0-4, it should see a "power good" signal asserted
on one of pca9552 GPIO pins 5-9.
To simulate this behavior, we simply connect the GPIO outputs for
pins 0-4 to the GPIO inputs for pins 5-9.
Each PCIe slot is assigned 3 GPIO pins on the pca9552 device, for
control of up to 5 PCIe slots. The per-slot signal names are:
SLOTx_EN.......PHYP uses this as an output to enable
slot power. We connect this to the
SLOTx_PG pin to simulate a PGOOD signal.
SLOTx_PG.......PHYP uses this as in input to detect
PGOOD for the slot. For our purposes
we just connect this to the SLOTx_EN
output.
SLOTx_Control..PHYP uses this as an output to prevent
a race condition in the real hotplug
circuitry, but we can ignore this output
for simulation.
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
1 file changed
