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kernel/linux-imx6_3.14.28/drivers/clocksource/mmio.c 1.86 KB
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  /*
   * Generic MMIO clocksource support
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #include <linux/clocksource.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  
  struct clocksource_mmio {
  	void __iomem *reg;
  	struct clocksource clksrc;
  };
  
  static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
  {
  	return container_of(c, struct clocksource_mmio, clksrc);
  }
  
  cycle_t clocksource_mmio_readl_up(struct clocksource *c)
  {
  	return readl_relaxed(to_mmio_clksrc(c)->reg);
  }
  
  cycle_t clocksource_mmio_readl_down(struct clocksource *c)
  {
  	return ~readl_relaxed(to_mmio_clksrc(c)->reg);
  }
  
  cycle_t clocksource_mmio_readw_up(struct clocksource *c)
  {
  	return readw_relaxed(to_mmio_clksrc(c)->reg);
  }
  
  cycle_t clocksource_mmio_readw_down(struct clocksource *c)
  {
  	return ~(unsigned)readw_relaxed(to_mmio_clksrc(c)->reg);
  }
  
  /**
   * clocksource_mmio_init - Initialize a simple mmio based clocksource
   * @base:	Virtual address of the clock readout register
   * @name:	Name of the clocksource
   * @hz:		Frequency of the clocksource in Hz
   * @rating:	Rating of the clocksource
   * @bits:	Number of valid bits
   * @read:	One of clocksource_mmio_read*() above
   */
  int __init clocksource_mmio_init(void __iomem *base, const char *name,
  	unsigned long hz, int rating, unsigned bits,
  	cycle_t (*read)(struct clocksource *))
  {
  	struct clocksource_mmio *cs;
  
  	if (bits > 32 || bits < 16)
  		return -EINVAL;
  
  	cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
  	if (!cs)
  		return -ENOMEM;
  
  	cs->reg = base;
  	cs->clksrc.name = name;
  	cs->clksrc.rating = rating;
  	cs->clksrc.read = read;
  	cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
  	cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
  
  	return clocksource_register_hz(&cs->clksrc, hz);
  }