PCI: Don't allow unbinding host controllers that aren't prepared

Many PCI host controller drivers aren't prepared to have their devices
unbound from them forcefully (e.g., through /sys/.../<driver>/unbind), as
they don't provide any driver .remove callback, where they'd detach the
root bus, release resources, etc. Keeping the driver built in (i.e., not a
loadable module) is not enough; and providing no .remove callback just
means we don't do any teardown.

To rule out the possibility of unbinding a device via sysfs, we need to set
the ".suppress_bind_attrs" field.

I found the suspect drivers via the following search:

  git grep -l platform_driver $(git grep -L -e '\.remove' -e suppress_bind_attrs drivers/pci/)

Then I inspected them to ensure that
(a) they set up a PCI bus in their probe() and
(b) they don't have a remove() callback for undoing the setup

Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/dwc/pci-imx6.c

@@ -804,6 +804,7 @@ static struct platform_driver imx6_pcie_driver = {
 	.driver = {
 		.name	= "imx6q-pcie",
 		.of_match_table = imx6_pcie_of_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe    = imx6_pcie_probe,
 	.shutdown = imx6_pcie_shutdown,

drivers/pci/dwc/pci-layerscape.c

@@ -305,6 +305,7 @@ static struct platform_driver ls_pcie_driver = {
 	.driver = {
 		.name = "layerscape-pcie",
 		.of_match_table = ls_pcie_of_match,
+		.suppress_bind_attrs = true,
 	},
 };
 builtin_platform_driver_probe(ls_pcie_driver, ls_pcie_probe);

drivers/pci/dwc/pcie-armada8k.c

@@ -262,6 +262,7 @@ static struct platform_driver armada8k_pcie_driver = {
 	.driver = {
 		.name	= "armada8k-pcie",
 		.of_match_table = of_match_ptr(armada8k_pcie_of_match),
+		.suppress_bind_attrs = true,
 	},
 };
 builtin_platform_driver(armada8k_pcie_driver);

drivers/pci/dwc/pcie-artpec6.c

@@ -295,6 +295,7 @@ static struct platform_driver artpec6_pcie_driver = {
 	.driver = {
 		.name	= "artpec6-pcie",
 		.of_match_table = artpec6_pcie_of_match,
+		.suppress_bind_attrs = true,
 	},
 };
 builtin_platform_driver(artpec6_pcie_driver);

drivers/pci/dwc/pcie-designware-plat.c

@@ -133,6 +133,7 @@ static struct platform_driver dw_plat_pcie_driver = {
 	.driver = {
 		.name	= "dw-pcie",
 		.of_match_table = dw_plat_pcie_of_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe = dw_plat_pcie_probe,
 };

drivers/pci/dwc/pcie-hisi.c

@@ -333,6 +333,7 @@ static struct platform_driver hisi_pcie_driver = {
 	.driver = {
 		   .name = "hisi-pcie",
 		   .of_match_table = hisi_pcie_of_match,
+		   .suppress_bind_attrs = true,
 	},
 };
 builtin_platform_driver(hisi_pcie_driver);
@@ -390,6 +391,7 @@ static struct platform_driver hisi_pcie_almost_ecam_driver = {
 	.driver = {
 		   .name = "hisi-pcie-almost-ecam",
 		   .of_match_table = hisi_pcie_almost_ecam_of_match,
+		   .suppress_bind_attrs = true,
 	},
 };
 builtin_platform_driver(hisi_pcie_almost_ecam_driver);

drivers/pci/dwc/pcie-spear13xx.c

@@ -308,6 +308,7 @@ static struct platform_driver spear13xx_pcie_driver = {
 	.driver = {
 		.name	= "spear-pcie",
 		.of_match_table = of_match_ptr(spear13xx_pcie_of_match),
+		.suppress_bind_attrs = true,
 	},
 };
 

drivers/pci/host/pci-ftpci100.c

@@ -556,6 +556,7 @@ static struct platform_driver faraday_pci_driver = {
 	.driver = {
 		.name = "ftpci100",
 		.of_match_table = of_match_ptr(faraday_pci_of_match),
+		.suppress_bind_attrs = true,
 	},
 	.probe  = faraday_pci_probe,
 };

drivers/pci/host/pci-host-generic.c

@@ -60,6 +60,7 @@ static struct platform_driver gen_pci_driver = {
 	.driver = {
 		.name = "pci-host-generic",
 		.of_match_table = gen_pci_of_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe = gen_pci_probe,
 };

drivers/pci/host/pci-thunder-ecam.c

@@ -373,6 +373,7 @@ static struct platform_driver thunder_ecam_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
 		.of_match_table = thunder_ecam_of_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe = thunder_ecam_probe,
 };

drivers/pci/host/pci-thunder-pem.c

@@ -474,6 +474,7 @@ static struct platform_driver thunder_pem_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
 		.of_match_table = thunder_pem_of_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe = thunder_pem_probe,
 };

drivers/pci/host/pci-versatile.c

@@ -222,6 +222,7 @@ static struct platform_driver versatile_pci_driver = {
 	.driver = {
 		.name = "versatile-pci",
 		.of_match_table = versatile_pci_of_match,
+		.suppress_bind_attrs = true,
 	},
 	.probe = versatile_pci_probe,
 };

drivers/pci/host/pci-xgene.c

@@ -697,6 +697,7 @@ static struct platform_driver xgene_pcie_driver = {
 	.driver = {
 		   .name = "xgene-pcie",
 		   .of_match_table = of_match_ptr(xgene_pcie_match_table),
+		   .suppress_bind_attrs = true,
 	},
 	.probe = xgene_pcie_probe_bridge,
 };