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>

hw/ppc/pnv.c

@@ -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));
     }
 }