diff options
Diffstat (limited to 'arch/mips/include')
| -rw-r--r-- | arch/mips/include/asm/clocksource.h | 29 | ||||
| -rw-r--r-- | arch/mips/include/asm/vdso.h | 68 |
2 files changed, 96 insertions, 1 deletions
diff --git a/arch/mips/include/asm/clocksource.h b/arch/mips/include/asm/clocksource.h new file mode 100644 index 0000000..3deb1d0 --- /dev/null +++ b/arch/mips/include/asm/clocksource.h @@ -0,0 +1,29 @@ +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Alex Smith <alex.smith@imgtec.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#ifndef __ASM_CLOCKSOURCE_H +#define __ASM_CLOCKSOURCE_H + +#include <linux/types.h> + +/* VDSO clocksources. */ +#define VDSO_CLOCK_NONE 0 /* No suitable clocksource. */ +#define VDSO_CLOCK_R4K 1 /* Use the coprocessor 0 count. */ +#define VDSO_CLOCK_GIC 2 /* Use the GIC. */ + +/** + * struct arch_clocksource_data - Architecture-specific clocksource information. + * @vdso_clock_mode: Method the VDSO should use to access the clocksource. + */ +struct arch_clocksource_data { + u8 vdso_clock_mode; +}; + +#endif /* __ASM_CLOCKSOURCE_H */ diff --git a/arch/mips/include/asm/vdso.h b/arch/mips/include/asm/vdso.h index db2d45b..8f4ca5d 100644 --- a/arch/mips/include/asm/vdso.h +++ b/arch/mips/include/asm/vdso.h @@ -13,6 +13,8 @@ #include <linux/mm_types.h> +#include <asm/barrier.h> + /** * struct mips_vdso_image - Details of a VDSO image. * @data: Pointer to VDSO image data (page-aligned). @@ -53,18 +55,82 @@ extern struct mips_vdso_image vdso_image_n32; /** * union mips_vdso_data - Data provided by the kernel for the VDSO. + * @xtime_sec: Current real time (seconds part). + * @xtime_nsec: Current real time (nanoseconds part, shifted). + * @wall_to_mono_sec: Wall-to-monotonic offset (seconds part). + * @wall_to_mono_nsec: Wall-to-monotonic offset (nanoseconds part). + * @seq_count: Counter to synchronise updates (odd = updating). + * @cs_shift: Clocksource shift value. + * @clock_mode: Clocksource to use for time functions. + * @cs_mult: Clocksource multiplier value. + * @cs_cycle_last: Clock cycle value at last update. + * @cs_mask: Clocksource mask value. + * @tz_minuteswest: Minutes west of Greenwich (from timezone). + * @tz_dsttime: Type of DST correction (from timezone). * * This structure contains data needed by functions within the VDSO. It is - * populated by the kernel and mapped read-only into user memory. + * populated by the kernel and mapped read-only into user memory. The time + * fields are mirrors of internal data from the timekeeping infrastructure. * * Note: Care should be taken when modifying as the layout must remain the same * for both 64- and 32-bit (for 32-bit userland on 64-bit kernel). */ union mips_vdso_data { struct { + u64 xtime_sec; + u64 xtime_nsec; + u32 wall_to_mono_sec; + u32 wall_to_mono_nsec; + u32 seq_count; + u32 cs_shift; + u8 clock_mode; + u32 cs_mult; + u64 cs_cycle_last; + u64 cs_mask; + s32 tz_minuteswest; + s32 tz_dsttime; }; u8 page[PAGE_SIZE]; }; +static inline u32 vdso_data_read_begin(const union mips_vdso_data *data) +{ + u32 seq; + + while (true) { + seq = ACCESS_ONCE(data->seq_count); + if (likely(!(seq & 1))) { + /* Paired with smp_wmb() in vdso_data_write_*(). */ + smp_rmb(); + return seq; + } + + cpu_relax(); + } +} + +static inline bool vdso_data_read_retry(const union mips_vdso_data *data, + u32 start_seq) +{ + /* Paired with smp_wmb() in vdso_data_write_*(). */ + smp_rmb(); + return unlikely(data->seq_count != start_seq); +} + +static inline void vdso_data_write_begin(union mips_vdso_data *data) +{ + ++data->seq_count; + + /* Ensure sequence update is written before other data page values. */ + smp_wmb(); +} + +static inline void vdso_data_write_end(union mips_vdso_data *data) +{ + /* Ensure data values are written before updating sequence again. */ + smp_wmb(); + ++data->seq_count; +} + #endif /* __ASM_VDSO_H */ |