xref: /openbmc/linux/drivers/clk/clk-fixed-rate.c (revision 57e20d68)
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 
devm_clk_hw_register_fixed_rate_release(struct device * dev,void * res)52 static void devm_clk_hw_register_fixed_rate_release(struct device *dev, void *res)
53 {
54 	struct clk_fixed_rate *fix = res;
55 
56 	/*
57 	 * We can not use clk_hw_unregister_fixed_rate, since it will kfree()
58 	 * the hw, resulting in double free. Just unregister the hw and let
59 	 * devres code kfree() it.
60 	 */
61 	clk_hw_unregister(&fix->hw);
62 }
63 
__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,bool devm)64 struct clk_hw *__clk_hw_register_fixed_rate(struct device *dev,
65 		struct device_node *np, const char *name,
66 		const char *parent_name, const struct clk_hw *parent_hw,
67 		const struct clk_parent_data *parent_data, unsigned long flags,
68 		unsigned long fixed_rate, unsigned long fixed_accuracy,
69 		unsigned long clk_fixed_flags, bool devm)
70 {
71 	struct clk_fixed_rate *fixed;
72 	struct clk_hw *hw;
73 	struct clk_init_data init = {};
74 	int ret = -EINVAL;
75 
76 	/* allocate fixed-rate clock */
77 	if (devm)
78 		fixed = devres_alloc(devm_clk_hw_register_fixed_rate_release,
79 				     sizeof(*fixed), GFP_KERNEL);
80 	else
81 		fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
82 	if (!fixed)
83 		return ERR_PTR(-ENOMEM);
84 
85 	init.name = name;
86 	init.ops = &clk_fixed_rate_ops;
87 	init.flags = flags;
88 	init.parent_names = parent_name ? &parent_name : NULL;
89 	init.parent_hws = parent_hw ? &parent_hw : NULL;
90 	init.parent_data = parent_data;
91 	if (parent_name || parent_hw || parent_data)
92 		init.num_parents = 1;
93 	else
94 		init.num_parents = 0;
95 
96 	/* struct clk_fixed_rate assignments */
97 	fixed->flags = clk_fixed_flags;
98 	fixed->fixed_rate = fixed_rate;
99 	fixed->fixed_accuracy = fixed_accuracy;
100 	fixed->hw.init = &init;
101 
102 	/* register the clock */
103 	hw = &fixed->hw;
104 	if (dev || !np)
105 		ret = clk_hw_register(dev, hw);
106 	else
107 		ret = of_clk_hw_register(np, hw);
108 	if (ret) {
109 		if (devm)
110 			devres_free(fixed);
111 		else
112 			kfree(fixed);
113 		hw = ERR_PTR(ret);
114 	} else if (devm)
115 		devres_add(dev, fixed);
116 
117 	return hw;
118 }
119 EXPORT_SYMBOL_GPL(__clk_hw_register_fixed_rate);
120 
clk_register_fixed_rate(struct device * dev,const char * name,const char * parent_name,unsigned long flags,unsigned long fixed_rate)121 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
122 		const char *parent_name, unsigned long flags,
123 		unsigned long fixed_rate)
124 {
125 	struct clk_hw *hw;
126 
127 	hw = clk_hw_register_fixed_rate_with_accuracy(dev, name, parent_name,
128 						      flags, fixed_rate, 0);
129 	if (IS_ERR(hw))
130 		return ERR_CAST(hw);
131 	return hw->clk;
132 }
133 EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
134 
clk_unregister_fixed_rate(struct clk * clk)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 
clk_hw_unregister_fixed_rate(struct clk_hw * hw)148 void clk_hw_unregister_fixed_rate(struct clk_hw *hw)
149 {
150 	struct clk_fixed_rate *fixed;
151 
152 	fixed = to_clk_fixed_rate(hw);
153 
154 	clk_hw_unregister(hw);
155 	kfree(fixed);
156 }
157 EXPORT_SYMBOL_GPL(clk_hw_unregister_fixed_rate);
158 
159 #ifdef CONFIG_OF
_of_fixed_clk_setup(struct device_node * node)160 static struct clk_hw *_of_fixed_clk_setup(struct device_node *node)
161 {
162 	struct clk_hw *hw;
163 	const char *clk_name = node->name;
164 	u32 rate;
165 	u32 accuracy = 0;
166 	int ret;
167 
168 	if (of_property_read_u32(node, "clock-frequency", &rate))
169 		return ERR_PTR(-EIO);
170 
171 	of_property_read_u32(node, "clock-accuracy", &accuracy);
172 
173 	of_property_read_string(node, "clock-output-names", &clk_name);
174 
175 	hw = clk_hw_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
176 						    0, rate, accuracy);
177 	if (IS_ERR(hw))
178 		return hw;
179 
180 	ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
181 	if (ret) {
182 		clk_hw_unregister_fixed_rate(hw);
183 		return ERR_PTR(ret);
184 	}
185 
186 	return hw;
187 }
188 
189 /**
190  * of_fixed_clk_setup() - Setup function for simple fixed rate clock
191  * @node:	device node for the clock
192  */
of_fixed_clk_setup(struct device_node * node)193 void __init of_fixed_clk_setup(struct device_node *node)
194 {
195 	_of_fixed_clk_setup(node);
196 }
197 CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
198 
of_fixed_clk_remove(struct platform_device * pdev)199 static void of_fixed_clk_remove(struct platform_device *pdev)
200 {
201 	struct clk_hw *hw = platform_get_drvdata(pdev);
202 
203 	of_clk_del_provider(pdev->dev.of_node);
204 	clk_hw_unregister_fixed_rate(hw);
205 }
206 
of_fixed_clk_probe(struct platform_device * pdev)207 static int of_fixed_clk_probe(struct platform_device *pdev)
208 {
209 	struct clk_hw *hw;
210 
211 	/*
212 	 * This function is not executed when of_fixed_clk_setup
213 	 * succeeded.
214 	 */
215 	hw = _of_fixed_clk_setup(pdev->dev.of_node);
216 	if (IS_ERR(hw))
217 		return PTR_ERR(hw);
218 
219 	platform_set_drvdata(pdev, hw);
220 
221 	return 0;
222 }
223 
224 static const struct of_device_id of_fixed_clk_ids[] = {
225 	{ .compatible = "fixed-clock" },
226 	{ }
227 };
228 
229 static struct platform_driver of_fixed_clk_driver = {
230 	.driver = {
231 		.name = "of_fixed_clk",
232 		.of_match_table = of_fixed_clk_ids,
233 	},
234 	.probe = of_fixed_clk_probe,
235 	.remove_new = of_fixed_clk_remove,
236 };
237 builtin_platform_driver(of_fixed_clk_driver);
238 #endif
239