soc/tegra: pmc: Fix early initialisation of PMC

During early initialisation, the available power partitions for a given
device is configured as well as the polarity of the PMC interrupt. Both
of which should only be configured if there is a valid device node for
the PMC device. This is because the soc data used for configuring the
power partitions is only available if a device node for the PMC is found
and the code to configure the interrupt polarity uses the device node
pointer directly.

Some early device-tree images may not have this device node and so fix
this by ensuring the device node pointer is valid when configuring these
items.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/soc/tegra/pmc.c

@@ -1550,16 +1550,17 @@ static int __init tegra_pmc_early_init(void)
 		return -ENXIO;
 	}
 
+	mutex_init(&pmc->powergates_lock);
+
+	if (np) {
 		/* Create a bit-map of the available and valid partitions */
 		for (i = 0; i < pmc->soc->num_powergates; i++)
 			if (pmc->soc->powergates[i])
 				set_bit(i, pmc->powergates_available);
 
-	mutex_init(&pmc->powergates_lock);
-
 		/*
-	 * Invert the interrupt polarity if a PMC device tree node exists and
-	 * contains the nvidia,invert-interrupt property.
+		 * Invert the interrupt polarity if a PMC device tree node
+		 * exists and contains the nvidia,invert-interrupt property.
 		 */
 		invert = of_property_read_bool(np, "nvidia,invert-interrupt");
 
@@ -1571,6 +1572,7 @@ static int __init tegra_pmc_early_init(void)
 			value &= ~PMC_CNTRL_INTR_POLARITY;
 
 		tegra_pmc_writel(value, PMC_CNTRL);
+	}
 
 	return 0;
 }