On 11/21/23 20:09, Glenn Miles wrote:
> 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.
>
> Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Thanks,
C.
> ---
>
> No change from previous version
>
> hw/ppc/pnv.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index d8d19fb065..088824fd9f 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -1900,7 +1900,24 @@ static void pnv_rainier_i2c_init(PnvMachineState *pnv)
> * Add a PCA9552 I2C device for PCIe hotplug control
> * to engine 2, bus 1, address 0x63
> */
> - i2c_slave_create_simple(chip10->i2c[2].busses[1], "pca9552", 0x63);
> + I2CSlave *hotplug = i2c_slave_create_simple(chip10->i2c[2].busses[1],
> + "pca9552", 0x63);
> +
> + /*
> + * Connect PCA9552 GPIO pins 0-4 (SLOTx_EN) outputs to GPIO pins 5-9
> + * (SLOTx_PG) inputs in order to fake the pgood state of PCIe slots
> + * after hypervisor code sets a SLOTx_EN pin high.
> + */
> + qdev_connect_gpio_out(DEVICE(hotplug), 0,
> + qdev_get_gpio_in(DEVICE(hotplug), 5));
> + qdev_connect_gpio_out(DEVICE(hotplug), 1,
> + qdev_get_gpio_in(DEVICE(hotplug), 6));
> + qdev_connect_gpio_out(DEVICE(hotplug), 2,
> + qdev_get_gpio_in(DEVICE(hotplug), 7));
> + qdev_connect_gpio_out(DEVICE(hotplug), 3,
> + qdev_get_gpio_in(DEVICE(hotplug), 8));
> + qdev_connect_gpio_out(DEVICE(hotplug), 4,
> + qdev_get_gpio_in(DEVICE(hotplug), 9));
> }
> }
>