The current code only supports the device tree based platforms. The code checks for the presence of a reset driver and calls the reset function pointer by looking up the reset driver as a module. ACPI defines _RST method to perform device level reset. After the _RST method is executed, the OS can resume using the device. The patchset is moving the device tree specific pieces out of the code to common functions so that ACPI support is added without impacting the rest of the code. During probe, the ACPI HID of the object will be saved and will be used to determine if this is an ACPI capable platform or not. If acpihid is NULL then, device tree functions are called. In addition to plumbing ACPI support, reset functionality is now a requirement by default. The code was allowing platform devices to be used without a supporting VFIO reset driver. The hardware can be left in some inconsistent state after a guest machine abort. The reset driver will put the hardware back to safe state and disable interrupts before returning the control back to the host machine. Adding a new reset_required kernel module option to platform VFIO drivers with a default value of true. New requirements are: 1. A reset function needs to be implemented by the corresponding driver via DT/ACPI. 2. The reset function needs to be discovered via DT/ACPI. The probe of the driver will fail if any of the above conditions are not satisfied. Changes from V8: 1. Return different error codes for the ACPI probe failures. 2. Document the CONFIG_ACPI and when/why error messages are printed along with assumptions. 3. Reorder the reset call in vfio_platform_call_reset for consistency. 4. Introduce VFIO_PLATFORM_IS_ACPI to make the code more readable 5. Get rid of the ACPI stub functions and inline the CONFIG_ACPI for code sharing. 6. Remove the reset_required kernel option from AMBA. 7. Change the permission to 444 for the reset_required kernel command line parameter. Sinan Kaya (9): vfio: platform: rename reset function vfio: platform: move reset call to a common function vfio: platform: determine reset capability vfio: platform: add support for ACPI probe vfio: platform: add extra debug info argument to call reset vfio: platform: call _RST method when using ACPI vfio, platform: make reset driver a requirement by default vfio: platform: check reset call return code during open vfio: platform: check reset call return code during release drivers/vfio/platform/vfio_amba.c | 1 + drivers/vfio/platform/vfio_platform.c | 5 + drivers/vfio/platform/vfio_platform_common.c | 200 ++++++++++++++++++++++---- drivers/vfio/platform/vfio_platform_private.h | 8 +- 4 files changed, 180 insertions(+), 34 deletions(-) -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
