LXR linux/drivers/clk/clk-fixed-rate.c

   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
  37static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
  38                unsigned long parent_accuracy)
  39{
  40        return to_clk_fixed_rate(hw)->fixed_accuracy;
  41}
  42
  43const struct clk_ops clk_fixed_rate_ops = {
  44        .recalc_rate = clk_fixed_rate_recalc_rate,
  45        .recalc_accuracy = clk_fixed_rate_recalc_accuracy,
  46};
  47EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
  48
  49/**
  50 * clk_register_fixed_rate_with_accuracy - register fixed-rate clock with the
  51 *                                         clock framework
  52 * @dev: device that is registering this clock
  53 * @name: name of this clock
  54 * @parent_name: name of clock's parent
  55 * @flags: framework-specific flags
  56 * @fixed_rate: non-adjustable clock rate
  57 * @fixed_accuracy: non-adjustable clock rate
  58 */
  59struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
  60                const char *name, const char *parent_name, unsigned long flags,
  61                unsigned long fixed_rate, unsigned long fixed_accuracy)
  62{
  63        struct clk_fixed_rate *fixed;
  64        struct clk *clk;
  65        struct clk_init_data init;
  66
  67        /* allocate fixed-rate clock */
  68        fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
  69        if (!fixed)
  70                return ERR_PTR(-ENOMEM);
  71
  72        init.name = name;
  73        init.ops = &clk_fixed_rate_ops;
  74        init.flags = flags | CLK_IS_BASIC;
  75        init.parent_names = (parent_name ? &parent_name: NULL);
  76        init.num_parents = (parent_name ? 1 : 0);
  77
  78        /* struct clk_fixed_rate assignments */
  79        fixed->fixed_rate = fixed_rate;
  80        fixed->fixed_accuracy = fixed_accuracy;
  81        fixed->hw.init = &init;
  82
  83        /* register the clock */
  84        clk = clk_register(dev, &fixed->hw);
  85        if (IS_ERR(clk))
  86                kfree(fixed);
  87
  88        return clk;
  89}
  90EXPORT_SYMBOL_GPL(clk_register_fixed_rate_with_accuracy);
  91
  92/**
  93 * clk_register_fixed_rate - register fixed-rate clock with the clock framework
  94 * @dev: device that is registering this clock
  95 * @name: name of this clock
  96 * @parent_name: name of clock's parent
  97 * @flags: framework-specific flags
  98 * @fixed_rate: non-adjustable clock rate
  99 */
 100struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
 101                const char *parent_name, unsigned long flags,
 102                unsigned long fixed_rate)
 103{
 104        return clk_register_fixed_rate_with_accuracy(dev, name, parent_name,
 105                                                     flags, fixed_rate, 0);
 106}
 107EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
 108
 109#ifdef CONFIG_OF
 110/**
 111 * of_fixed_clk_setup() - Setup function for simple fixed rate clock
 112 */
 113void of_fixed_clk_setup(struct device_node *node)
 114{
 115        struct clk *clk;
 116        const char *clk_name = node->name;
 117        u32 rate;
 118        u32 accuracy = 0;
 119
 120        if (of_property_read_u32(node, "clock-frequency", &rate))
 121                return;
 122
 123        of_property_read_u32(node, "clock-accuracy", &accuracy);
 124
 125        of_property_read_string(node, "clock-output-names", &clk_name);
 126
 127        clk = clk_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
 128                                                    CLK_IS_ROOT, rate,
 129                                                    accuracy);
 130        if (!IS_ERR(clk))
 131                of_clk_add_provider(node, of_clk_src_simple_get, clk);
 132}
 133EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
 134CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
 135#endif
 136