arch: x86: New MailBox support driver for Intel SOC's
Current Intel SOC cores use a MailBox Interface (MBI) to provide access to configuration registers on devices (called units) connected to the system fabric. This is a support driver that implements access to this interface on those platforms that can enumerate the device using PCI. Initial support is for BayTrail, for which port definitons are provided. This is a requirement for implementing platform specific features (e.g. RAPL driver requires this to perform platform specific power management using the registers in PUNIT). Dependant modules should select IOSF_MBI in their respective Kconfig configuraiton. Serialized access is handled by all exported routines with spinlocks. The API includes 3 functions for access to unit registers: int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr) int iosf_mbi_write(u8 port, u8 opcode, u32 offset, u32 mdr) int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask) port: indicating the unit being accessed opcode: the read or write port specific opcode offset: the register offset within the port mdr: the register data to be read, written, or modified mask: bit locations in mdr to change Returns nonzero on error Note: GPU code handles access to the GFX unit. Therefore access to that unit with this driver is disallowed to avoid conflicts. Signed-off-by: David E. Box <david.e.box@linux.intel.com> Link: http://lkml.kernel.org/r/1389216471-734-1-git-send-email-david.e.box@linux.intel.comSigned-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Matthew Garrett <mjg59@srcf.ucam.org>
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arch/x86/kernel/iosf_mbi.c
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