net: wwan: iosm: fix driver not working with INTEL_IOMMU disabled

With INTEL_IOMMU disable config or by forcing intel_iommu=off from
grub some of the features of IOSM driver like browsing, flashing &
coredump collection is not working.

When driver calls DMA API - dma_map_single() for tx transfers. It is
resulting in dma mapping error.

Set the device DMA addressing capabilities using dma_set_mask() and
remove the INTEL_IOMMU dependency in kconfig so that driver follows
the platform config either INTEL_IOMMU enable or disable.

Fixes: f7af616 ("net: iosm: infrastructure")
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/Kconfig

@@ -94,7 +94,7 @@ config RPMSG_WWAN_CTRL
 
 config IOSM
 	tristate "IOSM Driver for Intel M.2 WWAN Device"
-	depends on INTEL_IOMMU
+	depends on PCI
 	select NET_DEVLINK
 	select RELAY if WWAN_DEBUGFS
 	help

drivers/net/wwan/iosm/iosm_ipc_pcie.c

@@ -259,6 +259,7 @@ static int ipc_pcie_probe(struct pci_dev *pci,
 			  const struct pci_device_id *pci_id)
 {
 	struct iosm_pcie *ipc_pcie = kzalloc(sizeof(*ipc_pcie), GFP_KERNEL);
+	int ret;
 
 	pr_debug("Probing device 0x%X from the vendor 0x%X", pci_id->device,
 		 pci_id->vendor);
@@ -291,6 +292,12 @@ static int ipc_pcie_probe(struct pci_dev *pci,
 		goto pci_enable_fail;
 	}
 
+	ret = dma_set_mask(ipc_pcie->dev, DMA_BIT_MASK(64));
+	if (ret) {
+		dev_err(ipc_pcie->dev, "Could not set PCI DMA mask: %d", ret);
+		return ret;
+	}
+
 	ipc_pcie_config_aspm(ipc_pcie);
 	dev_dbg(ipc_pcie->dev, "PCIe device enabled.");