Root/drivers/clk/clk-fixed-factor.c

1/*
2 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Standard functionality for the common clock API.
9 */
10#include <linux/module.h>
11#include <linux/clk-provider.h>
12#include <linux/slab.h>
13#include <linux/err.h>
14
15/*
16 * DOC: basic fixed multiplier and divider clock that cannot gate
17 *
18 * Traits of this clock:
19 * prepare - clk_prepare only ensures that parents are prepared
20 * enable - clk_enable only ensures that parents are enabled
21 * rate - rate is fixed. clk->rate = parent->rate / div * mult
22 * parent - fixed parent. No clk_set_parent support
23 */
24
25#define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)
26
27static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
28        unsigned long parent_rate)
29{
30    struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
31    unsigned long long int rate;
32
33    rate = (unsigned long long int)parent_rate * fix->mult;
34    do_div(rate, fix->div);
35    return (unsigned long)rate;
36}
37
38static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
39                unsigned long *prate)
40{
41    struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
42
43    if (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
44        unsigned long best_parent;
45
46        best_parent = (rate / fix->mult) * fix->div;
47        *prate = __clk_round_rate(__clk_get_parent(hw->clk),
48                best_parent);
49    }
50
51    return (*prate / fix->div) * fix->mult;
52}
53
54static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
55                unsigned long parent_rate)
56{
57    return 0;
58}
59
60struct clk_ops clk_fixed_factor_ops = {
61    .round_rate = clk_factor_round_rate,
62    .set_rate = clk_factor_set_rate,
63    .recalc_rate = clk_factor_recalc_rate,
64};
65EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
66
67struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
68        const char *parent_name, unsigned long flags,
69        unsigned int mult, unsigned int div)
70{
71    struct clk_fixed_factor *fix;
72    struct clk_init_data init;
73    struct clk *clk;
74
75    fix = kmalloc(sizeof(*fix), GFP_KERNEL);
76    if (!fix) {
77        pr_err("%s: could not allocate fixed factor clk\n", __func__);
78        return ERR_PTR(-ENOMEM);
79    }
80
81    /* struct clk_fixed_factor assignments */
82    fix->mult = mult;
83    fix->div = div;
84    fix->hw.init = &init;
85
86    init.name = name;
87    init.ops = &clk_fixed_factor_ops;
88    init.flags = flags | CLK_IS_BASIC;
89    init.parent_names = &parent_name;
90    init.num_parents = 1;
91
92    clk = clk_register(dev, &fix->hw);
93
94    if (IS_ERR(clk))
95        kfree(fix);
96
97    return clk;
98}
99

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