linux/drivers/clk/clk-fixed-rate.c
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   1/*
   2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
   3 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 as
   7 * published by the Free Software Foundation.
   8 *
   9 * Fixed rate clock implementation
  10 */
  11
  12#include <linux/clk-provider.h>
  13#include <linux/module.h>
  14#include <linux/slab.h>
  15#include <linux/io.h>
  16#include <linux/err.h>
  17#include <linux/of.h>
  18
  19/*
  20 * DOC: basic fixed-rate clock that cannot gate
  21 *
  22 * Traits of this clock:
  23 * prepare - clk_(un)prepare only ensures parents are prepared
  24 * enable - clk_enable only ensures parents are enabled
  25 * rate - rate is always a fixed value.  No clk_set_rate support
  26 * parent - fixed parent.  No clk_set_parent support
  27 */
  28
  29#define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)
  30
  31static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
  32                unsigned long parent_rate)
  33{
  34        return to_clk_fixed_rate(hw)->fixed_rate;
  35}
  36
  37const struct clk_ops clk_fixed_rate_ops = {
  38        .recalc_rate = clk_fixed_rate_recalc_rate,
  39};
  40EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
  41
  42/**
  43 * clk_register_fixed_rate - register fixed-rate clock with the clock framework
  44 * @dev: device that is registering this clock
  45 * @name: name of this clock
  46 * @parent_name: name of clock's parent
  47 * @flags: framework-specific flags
  48 * @fixed_rate: non-adjustable clock rate
  49 */
  50struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
  51                const char *parent_name, unsigned long flags,
  52                unsigned long fixed_rate)
  53{
  54        struct clk_fixed_rate *fixed;
  55        struct clk *clk;
  56        struct clk_init_data init;
  57
  58        /* allocate fixed-rate clock */
  59        fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
  60        if (!fixed) {
  61                pr_err("%s: could not allocate fixed clk\n", __func__);
  62                return ERR_PTR(-ENOMEM);
  63        }
  64
  65        init.name = name;
  66        init.ops = &clk_fixed_rate_ops;
  67        init.flags = flags | CLK_IS_BASIC;
  68        init.parent_names = (parent_name ? &parent_name: NULL);
  69        init.num_parents = (parent_name ? 1 : 0);
  70
  71        /* struct clk_fixed_rate assignments */
  72        fixed->fixed_rate = fixed_rate;
  73        fixed->hw.init = &init;
  74
  75        /* register the clock */
  76        clk = clk_register(dev, &fixed->hw);
  77
  78        if (IS_ERR(clk))
  79                kfree(fixed);
  80
  81        return clk;
  82}
  83
  84#ifdef CONFIG_OF
  85/**
  86 * of_fixed_clk_setup() - Setup function for simple fixed rate clock
  87 */
  88void __init of_fixed_clk_setup(struct device_node *node)
  89{
  90        struct clk *clk;
  91        const char *clk_name = node->name;
  92        u32 rate;
  93
  94        if (of_property_read_u32(node, "clock-frequency", &rate))
  95                return;
  96
  97        of_property_read_string(node, "clock-output-names", &clk_name);
  98
  99        clk = clk_register_fixed_rate(NULL, clk_name, NULL, CLK_IS_ROOT, rate);
 100        if (!IS_ERR(clk))
 101                of_clk_add_provider(node, of_clk_src_simple_get, clk);
 102}
 103EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
 104#endif
 105
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