From f146c7bc85a51f95c05e0f8173d484eb301ece78 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Thu, 13 Aug 2026 18:52:04 +0200 Subject: PCI: Add pci_irq_type() to query the allocated interrupt type Add a helper that returns PCI_IRQ_MSIX, PCI_IRQ_MSI, or PCI_IRQ_INTX based on the interrupt type the PCI core selected after pci_alloc_irq_vectors(). Several drivers already open-code this check against pdev->msix_enabled and pdev->msi_enabled, or even open code this helper [1]. A common helper avoids the duplication and keeps drivers from accessing the bitfield directly (see also [2]). Acked-by: Bjorn Helgaas Tested-by: John Hubbard Link: https://elixir.bootlin.com/linux/v7.1/source/drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c#L196 [1] Inspired-by: John Hubbard Link: https://lore.kernel.org/all/DKKG2QM3YJYB.Z2H2B2UXJ75N@kernel.org/ [2] Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260813165234.620555-5-dakr@kernel.org [ Add missing pci_irq_type() stub for CONFIG_PCI=n. ] Signed-off-by: Danilo Krummrich --- Documentation/i2c/old-module-parameters.rst | 55 +++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 Documentation/i2c/old-module-parameters.rst (limited to 'Documentation/i2c/old-module-parameters.rst') diff --git a/Documentation/i2c/old-module-parameters.rst b/Documentation/i2c/old-module-parameters.rst new file mode 100644 index 000000000..b08b6daab --- /dev/null +++ b/Documentation/i2c/old-module-parameters.rst @@ -0,0 +1,55 @@ +================================================================ +I2C device driver binding control from user-space in old kernels +================================================================ + +.. NOTE:: + Note: this section is only relevant if you are handling some old code + found in kernel 2.6. If you work with more recent kernels, you can + safely skip this section. + +Up to kernel 2.6.32, many I2C drivers used helper macros provided by + which created standard module parameters to let the user +control how the driver would probe I2C buses and attach to devices. These +parameters were known as ``probe`` (to let the driver probe for an extra +address), ``force`` (to forcibly attach the driver to a given device) and +``ignore`` (to prevent a driver from probing a given address). + +With the conversion of the I2C subsystem to the standard device driver +binding model, it became clear that these per-module parameters were no +longer needed, and that a centralized implementation was possible. The new, +sysfs-based interface is described in +Documentation/i2c/instantiating-devices.rst, section +"Method 4: Instantiate from user-space". + +Below is a mapping from the old module parameters to the new interface. + +Attaching a driver to an I2C device +----------------------------------- + +Old method (module parameters):: + + # modprobe probe=1,0x2d + # modprobe force=1,0x2d + # modprobe force_=1,0x2d + +New method (sysfs interface):: + + # echo 0x2d > /sys/bus/i2c/devices/i2c-1/new_device + +Preventing a driver from attaching to an I2C device +--------------------------------------------------- + +Old method (module parameters):: + + # modprobe ignore=1,0x2f + +New method (sysfs interface):: + + # echo dummy 0x2f > /sys/bus/i2c/devices/i2c-1/new_device + # modprobe + +Of course, it is important to instantiate the ``dummy`` device before loading +the driver. The dummy device will be handled by i2c-core itself, preventing +other drivers from binding to it later on. If there is a real device at the +problematic address, and you want another driver to bind to it, then simply +pass the name of the device in question instead of ``dummy``. -- cgit v1.3.1