PCI: Add enable_device() and disable_device() callbacks for bridges

Some PCI host bridges require special handling when enabling or
disabling PCI devices. For example, the i.MX95 platform has a lookup
table to map Requester IDs to StreamIDs, which the SMMU and MSI
controller use to identify the source of DMA accesses.

Without this mapping, DMA accesses may target unintended memory, which
would corrupt memory or read the wrong data.

Add a host bridge enable_device() hook the imx6 driver can use to
configure the Requester ID to StreamID mapping. The hardware table isn't
big enough to map all possible Requester IDs, so this hook may fail if
no table space is available. In that case, return failure from
pci_enable_device().

It might make more sense to make pci_set_master() decline to enable bus
mastering and return failure, but it currently doesn't have a way to return
failure.

Link: https://lore.kernel.org/r/20250114-imx95_lut-v9-1-39f58dbed03a@nxp.com
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

2 files changed, 37 insertions, 1 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 0b29ec6e8e5e..773ca3cbd322 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2059,6 +2059,28 @@ int __weak pcibios_enable_device(struct pci_dev *dev, int bars)
 	return pci_enable_resources(dev, bars);
 }
 
+static int pci_host_bridge_enable_device(struct pci_dev *dev)
+{
+	struct pci_host_bridge *host_bridge = pci_find_host_bridge(dev->bus);
+	int err;
+
+	if (host_bridge && host_bridge->enable_device) {
+		err = host_bridge->enable_device(host_bridge, dev);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static void pci_host_bridge_disable_device(struct pci_dev *dev)
+{
+	struct pci_host_bridge *host_bridge = pci_find_host_bridge(dev->bus);
+
+	if (host_bridge && host_bridge->disable_device)
+		host_bridge->disable_device(host_bridge, dev);
+}
+
 static int do_pci_enable_device(struct pci_dev *dev, int bars)
 {
 	int err;
@@ -2074,9 +2096,13 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
 	if (bridge)
 		pcie_aspm_powersave_config_link(bridge);
 
+	err = pci_host_bridge_enable_device(dev);
+	if (err)
+		return err;
+
 	err = pcibios_enable_device(dev, bars);
 	if (err < 0)
-		return err;
+		goto err_enable;
 	pci_fixup_device(pci_fixup_enable, dev);
 
 	if (dev->msi_enabled || dev->msix_enabled)
@@ -2091,6 +2117,12 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
 	}
 
 	return 0;
+
+err_enable:
+	pci_host_bridge_disable_device(dev);
+
+	return err;
+
 }
 
 /**
@@ -2274,6 +2306,8 @@ void pci_disable_device(struct pci_dev *dev)
 	if (atomic_dec_return(&dev->enable_cnt) != 0)
 		return;
 
+	pci_host_bridge_disable_device(dev);
+
 	do_pci_disable_device(dev);
 
 	dev->is_busmaster = 0;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index db9b47ce3eef..bcbef004dd56 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -595,6 +595,8 @@ struct pci_host_bridge {
 	u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* Platform IRQ swizzler */
 	int (*map_irq)(const struct pci_dev *, u8, u8);
 	void (*release_fn)(struct pci_host_bridge *);
+	int (*enable_device)(struct pci_host_bridge *bridge, struct pci_dev *dev);
+	void (*disable_device)(struct pci_host_bridge *bridge, struct pci_dev *dev);
 	void		*release_data;
 	unsigned int	ignore_reset_delay:1;	/* For entire hierarchy */
 	unsigned int	no_ext_tags:1;		/* No Extended Tags */