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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>
This commit is contained in:
Glenn Miles 2024-02-05 17:40:16 +10:00 committed by Nicholas Piggin
parent 33467ecb86
commit 6f86885a74
1 changed files with 13 additions and 1 deletions
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14
hw/ppc/pnv.c
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@ -1900,7 +1900,19 @@ 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 *dev = 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(dev), 0, qdev_get_gpio_in(DEVICE(dev), 5));
qdev_connect_gpio_out(DEVICE(dev), 1, qdev_get_gpio_in(DEVICE(dev), 6));
qdev_connect_gpio_out(DEVICE(dev), 2, qdev_get_gpio_in(DEVICE(dev), 7));
qdev_connect_gpio_out(DEVICE(dev), 3, qdev_get_gpio_in(DEVICE(dev), 8));
qdev_connect_gpio_out(DEVICE(dev), 4, qdev_get_gpio_in(DEVICE(dev), 9));
}
}