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  
to_mmio_clksrc(struct clocksource * c)15  static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
16  {
17  	return container_of(c, struct clocksource_mmio, clksrc);
18  }
19  
clocksource_mmio_readl_up(struct clocksource * c)20  u64 clocksource_mmio_readl_up(struct clocksource *c)
21  {
22  	return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
23  }
24  
clocksource_mmio_readl_down(struct clocksource * c)25  u64 clocksource_mmio_readl_down(struct clocksource *c)
26  {
27  	return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
28  }
29  
clocksource_mmio_readw_up(struct clocksource * c)30  u64 clocksource_mmio_readw_up(struct clocksource *c)
31  {
32  	return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
33  }
34  
clocksource_mmio_readw_down(struct clocksource * c)35  u64 clocksource_mmio_readw_down(struct clocksource *c)
36  {
37  	return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
38  }
39  
40  /**
41   * clocksource_mmio_init - Initialize a simple mmio based clocksource
42   * @base:	Virtual address of the clock readout register
43   * @name:	Name of the clocksource
44   * @hz:		Frequency of the clocksource in Hz
45   * @rating:	Rating of the clocksource
46   * @bits:	Number of valid bits
47   * @read:	One of clocksource_mmio_read*() above
48   */
clocksource_mmio_init(void __iomem * base,const char * name,unsigned long hz,int rating,unsigned bits,u64 (* read)(struct clocksource *))49  int __init clocksource_mmio_init(void __iomem *base, const char *name,
50  	unsigned long hz, int rating, unsigned bits,
51  	u64 (*read)(struct clocksource *))
52  {
53  	struct clocksource_mmio *cs;
54  
55  	if (bits > 64 || bits < 16)
56  		return -EINVAL;
57  
58  	cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
59  	if (!cs)
60  		return -ENOMEM;
61  
62  	cs->reg = base;
63  	cs->clksrc.name = name;
64  	cs->clksrc.rating = rating;
65  	cs->clksrc.read = read;
66  	cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
67  	cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
68  
69  	return clocksource_register_hz(&cs->clksrc, hz);
70  }
71