1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Generic MMIO clocksource support 4 */ 5 #include <linux/clocksource.h> 6 #include <linux/errno.h> 7 #include <linux/init.h> 8 #include <linux/slab.h> 9 10 struct clocksource_mmio { 11 void __iomem *reg; 12 struct clocksource clksrc; 13 }; 14 15 static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c) 16 { 17 return container_of(c, struct clocksource_mmio, clksrc); 18 } 19 20 u64 clocksource_mmio_readl_up(struct clocksource *c) 21 { 22 return (u64)readl_relaxed(to_mmio_clksrc(c)->reg); 23 } 24 EXPORT_SYMBOL_GPL(clocksource_mmio_readl_up); 25 26 u64 clocksource_mmio_readl_down(struct clocksource *c) 27 { 28 return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask; 29 } 30 EXPORT_SYMBOL_GPL(clocksource_mmio_readl_down); 31 32 u64 clocksource_mmio_readw_up(struct clocksource *c) 33 { 34 return (u64)readw_relaxed(to_mmio_clksrc(c)->reg); 35 } 36 EXPORT_SYMBOL_GPL(clocksource_mmio_readw_up); 37 38 u64 clocksource_mmio_readw_down(struct clocksource *c) 39 { 40 return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask; 41 } 42 EXPORT_SYMBOL_GPL(clocksource_mmio_readw_down); 43 44 /** 45 * clocksource_mmio_init - Initialize a simple mmio based clocksource 46 * @base: Virtual address of the clock readout register 47 * @name: Name of the clocksource 48 * @hz: Frequency of the clocksource in Hz 49 * @rating: Rating of the clocksource 50 * @bits: Number of valid bits 51 * @read: One of clocksource_mmio_read*() above 52 */ 53 int clocksource_mmio_init(void __iomem *base, const char *name, 54 unsigned long hz, int rating, unsigned bits, 55 u64 (*read)(struct clocksource *)) 56 { 57 struct clocksource_mmio *cs; 58 59 if (bits > 64 || bits < 16) 60 return -EINVAL; 61 62 cs = kzalloc_obj(struct clocksource_mmio); 63 if (!cs) 64 return -ENOMEM; 65 66 cs->reg = base; 67 cs->clksrc.name = name; 68 cs->clksrc.rating = rating; 69 cs->clksrc.read = read; 70 cs->clksrc.mask = CLOCKSOURCE_MASK(bits); 71 cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; 72 73 return clocksource_register_hz(&cs->clksrc, hz); 74 } 75 EXPORT_SYMBOL_GPL(clocksource_mmio_init); 76