1 Commits

Author	SHA1	Message	Date
Wilken Gottwalt	3c881e05c8	hwspinlock: add sun6i hardware spinlock support ... Adds the sun6i_hwspinlock driver for the hardware spinlock unit found in most of the sun6i compatible SoCs. This unit provides at least 32 spinlocks in hardware. The implementation supports 32, 64, 128 or 256 32bit registers. A lock can be taken by reading a register and released by writing a 0 to it. This driver supports all 4 spinlock setups, but for now only the first setup (32 locks) seem to exist in available devices. This spinlock unit is shared between all ARM cores and the embedded companion core. All of them can take/release a lock with a single cycle operation. It can be used to sync access to devices shared by the ARM cores and the companion core. There are two ways to check if a lock is taken. The first way is to read a lock. If a 0 is returned, the lock was free and is taken now. If an 1 is returned, the caller has to try again. Which means the lock is taken. The second way is to read a 32bit wide status register where every bit represents one of the 32 first locks. According to the datasheets this status register supports only the 32 first locks. This is the reason the first way (lock read/write) approach is used to be able to cover all 256 locks in future devices. The driver also reports the amount of supported locks via debugfs. Reviewed-by: Samuel Holland <samuel@sholland.org> Acked-by: Maxime Ripard <maxime@cerno.tech> Signed-off-by: Wilken Gottwalt <wilken.gottwalt@posteo.net> Link: https://lore.kernel.org/r/bfd2b97307c2321b15c09683f4bd5e1fcc792f13.1615713499.git.wilken.gottwalt@posteo.net Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>	2021-05-27 22:19:42 -05:00