1 /* 2 * Generic MMIO clocksource support 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 #include <linux/clocksource.h> 9 #include <linux/errno.h> 10 #include <linux/init.h> 11 #include <linux/slab.h> 12 13 struct clocksource_mmio { 14 void __iomem *reg; 15 struct clocksource clksrc; 16 }; 17 18 static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c) 19 { 20 return container_of(c, struct clocksource_mmio, clksrc); 21 } 22 23 cycle_t clocksource_mmio_readl_up(struct clocksource *c) 24 { 25 return (cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg); 26 } 27 28 cycle_t clocksource_mmio_readl_down(struct clocksource *c) 29 { 30 return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask; 31 } 32 33 cycle_t clocksource_mmio_readw_up(struct clocksource *c) 34 { 35 return (cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg); 36 } 37 38 cycle_t clocksource_mmio_readw_down(struct clocksource *c) 39 { 40 return ~(cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask; 41 } 42 43 /** 44 * clocksource_mmio_init - Initialize a simple mmio based clocksource 45 * @base: Virtual address of the clock readout register 46 * @name: Name of the clocksource 47 * @hz: Frequency of the clocksource in Hz 48 * @rating: Rating of the clocksource 49 * @bits: Number of valid bits 50 * @read: One of clocksource_mmio_read*() above 51 */ 52 int __init clocksource_mmio_init(void __iomem *base, const char *name, 53 unsigned long hz, int rating, unsigned bits, 54 cycle_t (*read)(struct clocksource *)) 55 { 56 struct clocksource_mmio *cs; 57 58 if (bits > 64 || bits < 16) 59 return -EINVAL; 60 61 cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL); 62 if (!cs) 63 return -ENOMEM; 64 65 cs->reg = base; 66 cs->clksrc.name = name; 67 cs->clksrc.rating = rating; 68 cs->clksrc.read = read; 69 cs->clksrc.mask = CLOCKSOURCE_MASK(bits); 70 cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; 71 72 return clocksource_register_hz(&cs->clksrc, hz); 73 } 74