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 #include <linux/of.h>
15 
16 /*
17  * DOC: basic fixed multiplier and divider clock that cannot gate
18  *
19  * Traits of this clock:
20  * prepare - clk_prepare only ensures that parents are prepared
21  * enable - clk_enable only ensures that parents are enabled
22  * rate - rate is fixed.  clk->rate = parent->rate / div * mult
23  * parent - fixed parent.  No clk_set_parent support
24  */
25 
26 #define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)
27 
28 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
29 		unsigned long parent_rate)
30 {
31 	struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
32 	unsigned long long int rate;
33 
34 	rate = (unsigned long long int)parent_rate * fix->mult;
35 	do_div(rate, fix->div);
36 	return (unsigned long)rate;
37 }
38 
39 static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
40 				unsigned long *prate)
41 {
42 	struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
43 
44 	if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
45 		unsigned long best_parent;
46 
47 		best_parent = (rate / fix->mult) * fix->div;
48 		*prate = clk_hw_round_rate(clk_hw_get_parent(hw), best_parent);
49 	}
50 
51 	return (*prate / fix->div) * fix->mult;
52 }
53 
54 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
55 				unsigned long parent_rate)
56 {
57 	/*
58 	 * We must report success but we can do so unconditionally because
59 	 * clk_factor_round_rate returns values that ensure this call is a
60 	 * nop.
61 	 */
62 
63 	return 0;
64 }
65 
66 const struct clk_ops clk_fixed_factor_ops = {
67 	.round_rate = clk_factor_round_rate,
68 	.set_rate = clk_factor_set_rate,
69 	.recalc_rate = clk_factor_recalc_rate,
70 };
71 EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
72 
73 struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
74 		const char *parent_name, unsigned long flags,
75 		unsigned int mult, unsigned int div)
76 {
77 	struct clk_fixed_factor *fix;
78 	struct clk_init_data init;
79 	struct clk *clk;
80 
81 	fix = kmalloc(sizeof(*fix), GFP_KERNEL);
82 	if (!fix)
83 		return ERR_PTR(-ENOMEM);
84 
85 	/* struct clk_fixed_factor assignments */
86 	fix->mult = mult;
87 	fix->div = div;
88 	fix->hw.init = &init;
89 
90 	init.name = name;
91 	init.ops = &clk_fixed_factor_ops;
92 	init.flags = flags | CLK_IS_BASIC;
93 	init.parent_names = &parent_name;
94 	init.num_parents = 1;
95 
96 	clk = clk_register(dev, &fix->hw);
97 
98 	if (IS_ERR(clk))
99 		kfree(fix);
100 
101 	return clk;
102 }
103 EXPORT_SYMBOL_GPL(clk_register_fixed_factor);
104 
105 #ifdef CONFIG_OF
106 /**
107  * of_fixed_factor_clk_setup() - Setup function for simple fixed factor clock
108  */
109 void __init of_fixed_factor_clk_setup(struct device_node *node)
110 {
111 	struct clk *clk;
112 	const char *clk_name = node->name;
113 	const char *parent_name;
114 	u32 div, mult;
115 
116 	if (of_property_read_u32(node, "clock-div", &div)) {
117 		pr_err("%s Fixed factor clock <%s> must have a clock-div property\n",
118 			__func__, node->name);
119 		return;
120 	}
121 
122 	if (of_property_read_u32(node, "clock-mult", &mult)) {
123 		pr_err("%s Fixed factor clock <%s> must have a clock-mult property\n",
124 			__func__, node->name);
125 		return;
126 	}
127 
128 	of_property_read_string(node, "clock-output-names", &clk_name);
129 	parent_name = of_clk_get_parent_name(node, 0);
130 
131 	clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0,
132 					mult, div);
133 	if (!IS_ERR(clk))
134 		of_clk_add_provider(node, of_clk_src_simple_get, clk);
135 }
136 EXPORT_SYMBOL_GPL(of_fixed_factor_clk_setup);
137 CLK_OF_DECLARE(fixed_factor_clk, "fixed-factor-clock",
138 		of_fixed_factor_clk_setup);
139 #endif
140