This adds a SMA algorithm inspired by Exponentially weighted moving average (EWMA) algorithm found in the kernel.
Signed-off-by: Christian Gmeiner christian.gmeiner@gmail.com --- drivers/gpu/drm/etnaviv/etnaviv_sma.h | 53 +++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 drivers/gpu/drm/etnaviv/etnaviv_sma.h
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_sma.h b/drivers/gpu/drm/etnaviv/etnaviv_sma.h new file mode 100644 index 000000000000..81564d5cbdc3 --- /dev/null +++ b/drivers/gpu/drm/etnaviv/etnaviv_sma.h @@ -0,0 +1,53 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2020 Etnaviv Project + */ + +#ifndef __ETNAVIV_SMA_H__ +#define __ETNAVIV_SMA_H__ + +#include <linux/bug.h> +#include <linux/compiler.h> + +/* + * Simple moving average (SMA) + * + * This implements a fixed-size SMA algorithm. + * + * The first argument to the macro is the name that will be used + * for the struct and helper functions. + * + * The second argument, the samples, expresses how many samples are + * used for the SMA algorithm. + */ + +#define DECLARE_SMA(name, _samples) \ + struct sma_##name { \ + unsigned long pos; \ + unsigned long sum; \ + unsigned long samples[_samples]; \ + }; \ + static inline void sma_##name##_init(struct sma_##name *s) \ + { \ + BUILD_BUG_ON(!__builtin_constant_p(_samples)); \ + memset(s, 0, sizeof(struct sma_##name)); \ + } \ + static inline unsigned long sma_##name##_read(struct sma_##name *s) \ + { \ + BUILD_BUG_ON(!__builtin_constant_p(_samples)); \ + return s->sum / _samples; \ + } \ + static inline void sma_##name##_add(struct sma_##name *s, unsigned long val) \ + { \ + unsigned long pos = READ_ONCE(s->pos); \ + unsigned long sum = READ_ONCE(s->sum); \ + unsigned long sample = READ_ONCE(s->samples[pos]); \ + \ + BUILD_BUG_ON(!__builtin_constant_p(_samples)); \ + \ + WRITE_ONCE(s->sum, sum - sample + val); \ + WRITE_ONCE(s->samples[pos], val); \ + WRITE_ONCE(s->pos, pos + 1 == _samples ? 0 : pos + 1); \ + } + +#endif /* __ETNAVIV_SMA_H__ */