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Re: [PATCH v4 05/11] ppc/pnv: Wire up pca9552 GPIO pins for PCIe hotplug
From: |
Miles Glenn |
Subject: |
Re: [PATCH v4 05/11] ppc/pnv: Wire up pca9552 GPIO pins for PCIe hotplug power control |
Date: |
Tue, 21 Nov 2023 14:03:19 -0600 |
On Tue, 2023-11-21 at 19:36 +0100, Cédric Le Goater wrote:
> On 11/21/23 00:51, 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.
>
> And this is what OPAL is not doing :
>
>
> https://github.com/open-power/skiboot/blob/master/platforms/astbmc/rainier.c#L65
>
> Correct ?
>
Ah, yes, I believe you are correct!
> > 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>
> > ---
> >
> > Changes from previous version:
> > - Code moved from pnv_chip_power10_realize to
> > pnv_rainier_i2c_init
> >
> > hw/ppc/pnv.c | 20 ++++++++++++++++++--
> > 1 file changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> > index 9cefcd0fd6..80d25fc1bd 100644
> > --- a/hw/ppc/pnv.c
> > +++ b/hw/ppc/pnv.c
> > @@ -1898,8 +1898,24 @@ 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);
>
> hotplug ? why not dev simply ?
>
>
> Thanks,
>
> C.
>
>
Sure, dev is fine. I'll change it.
Thanks,
Glenn
>
> > +
> > + /*
> > + * 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));
> > }
> > }
> >
- [PATCH v4 00/11] Add powernv10 I2C devices and tests, Glenn Miles, 2023/11/20
- [PATCH v4 08/11] ppc/pnv: Use resettable interface to reset child I2C buses, Glenn Miles, 2023/11/20
- [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Glenn Miles, 2023/11/20
- Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Nicholas Piggin, 2023/11/20
- Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Cédric Le Goater, 2023/11/21
- Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Miles Glenn, 2023/11/21
- Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Cédric Le Goater, 2023/11/21
- Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Cédric Le Goater, 2023/11/21
- Re: [PATCH v4 03/11] ppc/pnv: New powernv10-rainier machine type, Miles Glenn, 2023/11/21