xref: /openbmc/linux/drivers/clk/clk-fixed-rate.c (revision 4f205687)
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 static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
30 		unsigned long parent_rate)
31 {
32 	return to_clk_fixed_rate(hw)->fixed_rate;
33 }
34 
35 static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
36 		unsigned long parent_accuracy)
37 {
38 	return to_clk_fixed_rate(hw)->fixed_accuracy;
39 }
40 
41 const struct clk_ops clk_fixed_rate_ops = {
42 	.recalc_rate = clk_fixed_rate_recalc_rate,
43 	.recalc_accuracy = clk_fixed_rate_recalc_accuracy,
44 };
45 EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
46 
47 /**
48  * clk_hw_register_fixed_rate_with_accuracy - register fixed-rate clock with
49  * the clock framework
50  * @dev: device that is registering this clock
51  * @name: name of this clock
52  * @parent_name: name of clock's parent
53  * @flags: framework-specific flags
54  * @fixed_rate: non-adjustable clock rate
55  * @fixed_accuracy: non-adjustable clock rate
56  */
57 struct clk_hw *clk_hw_register_fixed_rate_with_accuracy(struct device *dev,
58 		const char *name, const char *parent_name, unsigned long flags,
59 		unsigned long fixed_rate, unsigned long fixed_accuracy)
60 {
61 	struct clk_fixed_rate *fixed;
62 	struct clk_hw *hw;
63 	struct clk_init_data init;
64 	int ret;
65 
66 	/* allocate fixed-rate clock */
67 	fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
68 	if (!fixed)
69 		return ERR_PTR(-ENOMEM);
70 
71 	init.name = name;
72 	init.ops = &clk_fixed_rate_ops;
73 	init.flags = flags | CLK_IS_BASIC;
74 	init.parent_names = (parent_name ? &parent_name: NULL);
75 	init.num_parents = (parent_name ? 1 : 0);
76 
77 	/* struct clk_fixed_rate assignments */
78 	fixed->fixed_rate = fixed_rate;
79 	fixed->fixed_accuracy = fixed_accuracy;
80 	fixed->hw.init = &init;
81 
82 	/* register the clock */
83 	hw = &fixed->hw;
84 	ret = clk_hw_register(dev, hw);
85 	if (ret) {
86 		kfree(fixed);
87 		hw = ERR_PTR(ret);
88 	}
89 
90 	return hw;
91 }
92 EXPORT_SYMBOL_GPL(clk_hw_register_fixed_rate_with_accuracy);
93 
94 struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
95 		const char *name, const char *parent_name, unsigned long flags,
96 		unsigned long fixed_rate, unsigned long fixed_accuracy)
97 {
98 	struct clk_hw *hw;
99 
100 	hw = clk_hw_register_fixed_rate_with_accuracy(dev, name, parent_name,
101 			flags, fixed_rate, fixed_accuracy);
102 	if (IS_ERR(hw))
103 		return ERR_CAST(hw);
104 	return hw->clk;
105 }
106 EXPORT_SYMBOL_GPL(clk_register_fixed_rate_with_accuracy);
107 
108 /**
109  * clk_hw_register_fixed_rate - register fixed-rate clock with the clock
110  * framework
111  * @dev: device that is registering this clock
112  * @name: name of this clock
113  * @parent_name: name of clock's parent
114  * @flags: framework-specific flags
115  * @fixed_rate: non-adjustable clock rate
116  */
117 struct clk_hw *clk_hw_register_fixed_rate(struct device *dev, const char *name,
118 		const char *parent_name, unsigned long flags,
119 		unsigned long fixed_rate)
120 {
121 	return clk_hw_register_fixed_rate_with_accuracy(dev, name, parent_name,
122 						     flags, fixed_rate, 0);
123 }
124 EXPORT_SYMBOL_GPL(clk_hw_register_fixed_rate);
125 
126 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
127 		const char *parent_name, unsigned long flags,
128 		unsigned long fixed_rate)
129 {
130 	return clk_register_fixed_rate_with_accuracy(dev, name, parent_name,
131 						     flags, fixed_rate, 0);
132 }
133 EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
134 
135 void clk_unregister_fixed_rate(struct clk *clk)
136 {
137 	struct clk_hw *hw;
138 
139 	hw = __clk_get_hw(clk);
140 	if (!hw)
141 		return;
142 
143 	clk_unregister(clk);
144 	kfree(to_clk_fixed_rate(hw));
145 }
146 EXPORT_SYMBOL_GPL(clk_unregister_fixed_rate);
147 
148 #ifdef CONFIG_OF
149 /**
150  * of_fixed_clk_setup() - Setup function for simple fixed rate clock
151  */
152 void of_fixed_clk_setup(struct device_node *node)
153 {
154 	struct clk *clk;
155 	const char *clk_name = node->name;
156 	u32 rate;
157 	u32 accuracy = 0;
158 
159 	if (of_property_read_u32(node, "clock-frequency", &rate))
160 		return;
161 
162 	of_property_read_u32(node, "clock-accuracy", &accuracy);
163 
164 	of_property_read_string(node, "clock-output-names", &clk_name);
165 
166 	clk = clk_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
167 						    0, rate, accuracy);
168 	if (!IS_ERR(clk))
169 		of_clk_add_provider(node, of_clk_src_simple_get, clk);
170 }
171 EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
172 CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
173 #endif
174