1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
4  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
5  *
6  * Fixed rate clock implementation
7  */
8 
9 #include <linux/clk-provider.h>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/io.h>
13 #include <linux/err.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 
17 /*
18  * DOC: basic fixed-rate clock that cannot gate
19  *
20  * Traits of this clock:
21  * prepare - clk_(un)prepare only ensures parents are prepared
22  * enable - clk_enable only ensures parents are enabled
23  * rate - rate is always a fixed value.  No clk_set_rate support
24  * parent - fixed parent.  No clk_set_parent support
25  */
26 
27 #define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)
28 
clk_fixed_rate_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)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 
clk_fixed_rate_recalc_accuracy(struct clk_hw * hw,unsigned long parent_accuracy)35 static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
36 		unsigned long parent_accuracy)
37 {
38 	struct clk_fixed_rate *fixed = to_clk_fixed_rate(hw);
39 
40 	if (fixed->flags & CLK_FIXED_RATE_PARENT_ACCURACY)
41 		return parent_accuracy;
42 
43 	return fixed->fixed_accuracy;
44 }
45 
46 const struct clk_ops clk_fixed_rate_ops = {
47 	.recalc_rate = clk_fixed_rate_recalc_rate,
48 	.recalc_accuracy = clk_fixed_rate_recalc_accuracy,
49 };
50 EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
51 
__clk_hw_register_fixed_rate(struct device * dev,struct device_node * np,const char * name,const char * parent_name,const struct clk_hw * parent_hw,const struct clk_parent_data * parent_data,unsigned long flags,unsigned long fixed_rate,unsigned long fixed_accuracy,unsigned long clk_fixed_flags)52 struct clk_hw *__clk_hw_register_fixed_rate(struct device *dev,
53 		struct device_node *np, const char *name,
54 		const char *parent_name, const struct clk_hw *parent_hw,
55 		const struct clk_parent_data *parent_data, unsigned long flags,
56 		unsigned long fixed_rate, unsigned long fixed_accuracy,
57 		unsigned long clk_fixed_flags)
58 {
59 	struct clk_fixed_rate *fixed;
60 	struct clk_hw *hw;
61 	struct clk_init_data init = {};
62 	int ret = -EINVAL;
63 
64 	/* allocate fixed-rate clock */
65 	fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
66 	if (!fixed)
67 		return ERR_PTR(-ENOMEM);
68 
69 	init.name = name;
70 	init.ops = &clk_fixed_rate_ops;
71 	init.flags = flags;
72 	init.parent_names = parent_name ? &parent_name : NULL;
73 	init.parent_hws = parent_hw ? &parent_hw : NULL;
74 	init.parent_data = parent_data;
75 	if (parent_name || parent_hw || parent_data)
76 		init.num_parents = 1;
77 	else
78 		init.num_parents = 0;
79 
80 	/* struct clk_fixed_rate assignments */
81 	fixed->flags = clk_fixed_flags;
82 	fixed->fixed_rate = fixed_rate;
83 	fixed->fixed_accuracy = fixed_accuracy;
84 	fixed->hw.init = &init;
85 
86 	/* register the clock */
87 	hw = &fixed->hw;
88 	if (dev || !np)
89 		ret = clk_hw_register(dev, hw);
90 	else if (np)
91 		ret = of_clk_hw_register(np, hw);
92 	if (ret) {
93 		kfree(fixed);
94 		hw = ERR_PTR(ret);
95 	}
96 
97 	return hw;
98 }
99 EXPORT_SYMBOL_GPL(__clk_hw_register_fixed_rate);
100 
clk_register_fixed_rate(struct device * dev,const char * name,const char * parent_name,unsigned long flags,unsigned long fixed_rate)101 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
102 		const char *parent_name, unsigned long flags,
103 		unsigned long fixed_rate)
104 {
105 	struct clk_hw *hw;
106 
107 	hw = clk_hw_register_fixed_rate_with_accuracy(dev, name, parent_name,
108 						      flags, fixed_rate, 0);
109 	if (IS_ERR(hw))
110 		return ERR_CAST(hw);
111 	return hw->clk;
112 }
113 EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
114 
clk_unregister_fixed_rate(struct clk * clk)115 void clk_unregister_fixed_rate(struct clk *clk)
116 {
117 	struct clk_hw *hw;
118 
119 	hw = __clk_get_hw(clk);
120 	if (!hw)
121 		return;
122 
123 	clk_unregister(clk);
124 	kfree(to_clk_fixed_rate(hw));
125 }
126 EXPORT_SYMBOL_GPL(clk_unregister_fixed_rate);
127 
clk_hw_unregister_fixed_rate(struct clk_hw * hw)128 void clk_hw_unregister_fixed_rate(struct clk_hw *hw)
129 {
130 	struct clk_fixed_rate *fixed;
131 
132 	fixed = to_clk_fixed_rate(hw);
133 
134 	clk_hw_unregister(hw);
135 	kfree(fixed);
136 }
137 EXPORT_SYMBOL_GPL(clk_hw_unregister_fixed_rate);
138 
139 #ifdef CONFIG_OF
_of_fixed_clk_setup(struct device_node * node)140 static struct clk_hw *_of_fixed_clk_setup(struct device_node *node)
141 {
142 	struct clk_hw *hw;
143 	const char *clk_name = node->name;
144 	u32 rate;
145 	u32 accuracy = 0;
146 	int ret;
147 
148 	if (of_property_read_u32(node, "clock-frequency", &rate))
149 		return ERR_PTR(-EIO);
150 
151 	of_property_read_u32(node, "clock-accuracy", &accuracy);
152 
153 	of_property_read_string(node, "clock-output-names", &clk_name);
154 
155 	hw = clk_hw_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
156 						    0, rate, accuracy);
157 	if (IS_ERR(hw))
158 		return hw;
159 
160 	ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
161 	if (ret) {
162 		clk_hw_unregister_fixed_rate(hw);
163 		return ERR_PTR(ret);
164 	}
165 
166 	return hw;
167 }
168 
169 /**
170  * of_fixed_clk_setup() - Setup function for simple fixed rate clock
171  * @node:	device node for the clock
172  */
of_fixed_clk_setup(struct device_node * node)173 void __init of_fixed_clk_setup(struct device_node *node)
174 {
175 	_of_fixed_clk_setup(node);
176 }
177 CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
178 
of_fixed_clk_remove(struct platform_device * pdev)179 static int of_fixed_clk_remove(struct platform_device *pdev)
180 {
181 	struct clk_hw *hw = platform_get_drvdata(pdev);
182 
183 	of_clk_del_provider(pdev->dev.of_node);
184 	clk_hw_unregister_fixed_rate(hw);
185 
186 	return 0;
187 }
188 
of_fixed_clk_probe(struct platform_device * pdev)189 static int of_fixed_clk_probe(struct platform_device *pdev)
190 {
191 	struct clk_hw *hw;
192 
193 	/*
194 	 * This function is not executed when of_fixed_clk_setup
195 	 * succeeded.
196 	 */
197 	hw = _of_fixed_clk_setup(pdev->dev.of_node);
198 	if (IS_ERR(hw))
199 		return PTR_ERR(hw);
200 
201 	platform_set_drvdata(pdev, hw);
202 
203 	return 0;
204 }
205 
206 static const struct of_device_id of_fixed_clk_ids[] = {
207 	{ .compatible = "fixed-clock" },
208 	{ }
209 };
210 
211 static struct platform_driver of_fixed_clk_driver = {
212 	.driver = {
213 		.name = "of_fixed_clk",
214 		.of_match_table = of_fixed_clk_ids,
215 	},
216 	.probe = of_fixed_clk_probe,
217 	.remove = of_fixed_clk_remove,
218 };
219 builtin_platform_driver(of_fixed_clk_driver);
220 #endif
221