On 01/16/18 18:50, Sukadev Bhattiprolu wrote:
> The Fast Thread Wake-up (FTW) driver provides user space applications an
> interface to the low latency Core-to-Core wakeup functionality in POWER9.
>
> This mechanism allows a thread on one core to efficiently send a message
> to a "waiting thread" on another core on the same chip, using the Virtual
> Accelrator Switchboard (VAS) subsystem.
>
> This initial FTW driver implements the ioctl and mmap operations on an
> FTW device node. Using these operations, a pair of application threads
> can establish a "communication channel" and use the COPY, PASTE and WAIT
> instructions to wait/wake up.
>
> PATCH 5/5 documents the API and includes an example of the usage.
>
> Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
> ---
> Changelog[v2]
> - [Michael Neuling] Rename from drop "nx" from name "nx-ftw".
> - [Michael Neuling] Use a single VAS_FTW_SETUP ioctl to simplify
> interface.
> - [Michael Ellerman] To work with paste emulation patch, mark
> PTE dirty in ->mmap() to ensure there is no fault on paste
> (the emulation patch must disable pagefaults when updating
> thread reconfig registers).
> - Check return value from set_thread_tidr().
> - Move driver drivers/misc/ftw.
>
> ---
> drivers/misc/Kconfig | 1 +
> drivers/misc/Makefile | 1 +
> drivers/misc/ftw/Kconfig | 16 +++
> drivers/misc/ftw/Makefile | 4 +
> drivers/misc/ftw/ftw.c | 346
> ++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 368 insertions(+)
> create mode 100644 drivers/misc/ftw/Kconfig
> create mode 100644 drivers/misc/ftw/Makefile
> create mode 100644 drivers/misc/ftw/ftw.c
> +static long ftw_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
> +{
> + switch (cmd) {
> +
> + case FTW_SETUP:
> + return ftw_ioc_ftw_setup(fp, arg);
> +
> + default:
> + return -EINVAL;
> + }
> +}
Nit: some versions of gcc (or maybe clang) complain about a typed function
not always having a return value in code like above, so it is often done as:
> +static long ftw_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
> +{
> + switch (cmd) {
> +
> + case FTW_SETUP:
> + return ftw_ioc_ftw_setup(fp, arg);
> +
> + default:
> + break;
> + }
return -EINVAL;
> +}
Do you expect to implement more ioctls? If not, just change the switch to
an if ().
--
~Randy
