xref: /openbmc/linux/drivers/clk/clk-gpio.c (revision a96cbb14)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com
4  *
5  * Authors:
6  *    Jyri Sarha <jsarha@ti.com>
7  *    Sergej Sawazki <ce3a@gmx.de>
8  *
9  * Gpio controlled clock implementation
10  */
11 
12 #include <linux/clk-provider.h>
13 #include <linux/export.h>
14 #include <linux/slab.h>
15 #include <linux/gpio/consumer.h>
16 #include <linux/err.h>
17 #include <linux/device.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 
21 /**
22  * DOC: basic gpio gated clock which can be enabled and disabled
23  *      with gpio output
24  * Traits of this clock:
25  * prepare - clk_(un)prepare only ensures parent is (un)prepared
26  * enable - clk_enable and clk_disable are functional & control gpio
27  * rate - inherits rate from parent.  No clk_set_rate support
28  * parent - fixed parent.  No clk_set_parent support
29  */
30 
31 /**
32  * struct clk_gpio - gpio gated clock
33  *
34  * @hw:		handle between common and hardware-specific interfaces
35  * @gpiod:	gpio descriptor
36  *
37  * Clock with a gpio control for enabling and disabling the parent clock
38  * or switching between two parents by asserting or deasserting the gpio.
39  *
40  * Implements .enable, .disable and .is_enabled or
41  * .get_parent, .set_parent and .determine_rate depending on which clk_ops
42  * is used.
43  */
44 struct clk_gpio {
45 	struct clk_hw	hw;
46 	struct gpio_desc *gpiod;
47 };
48 
49 #define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
50 
clk_gpio_gate_enable(struct clk_hw * hw)51 static int clk_gpio_gate_enable(struct clk_hw *hw)
52 {
53 	struct clk_gpio *clk = to_clk_gpio(hw);
54 
55 	gpiod_set_value(clk->gpiod, 1);
56 
57 	return 0;
58 }
59 
clk_gpio_gate_disable(struct clk_hw * hw)60 static void clk_gpio_gate_disable(struct clk_hw *hw)
61 {
62 	struct clk_gpio *clk = to_clk_gpio(hw);
63 
64 	gpiod_set_value(clk->gpiod, 0);
65 }
66 
clk_gpio_gate_is_enabled(struct clk_hw * hw)67 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
68 {
69 	struct clk_gpio *clk = to_clk_gpio(hw);
70 
71 	return gpiod_get_value(clk->gpiod);
72 }
73 
74 static const struct clk_ops clk_gpio_gate_ops = {
75 	.enable = clk_gpio_gate_enable,
76 	.disable = clk_gpio_gate_disable,
77 	.is_enabled = clk_gpio_gate_is_enabled,
78 };
79 
clk_sleeping_gpio_gate_prepare(struct clk_hw * hw)80 static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
81 {
82 	struct clk_gpio *clk = to_clk_gpio(hw);
83 
84 	gpiod_set_value_cansleep(clk->gpiod, 1);
85 
86 	return 0;
87 }
88 
clk_sleeping_gpio_gate_unprepare(struct clk_hw * hw)89 static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
90 {
91 	struct clk_gpio *clk = to_clk_gpio(hw);
92 
93 	gpiod_set_value_cansleep(clk->gpiod, 0);
94 }
95 
clk_sleeping_gpio_gate_is_prepared(struct clk_hw * hw)96 static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
97 {
98 	struct clk_gpio *clk = to_clk_gpio(hw);
99 
100 	return gpiod_get_value_cansleep(clk->gpiod);
101 }
102 
103 static const struct clk_ops clk_sleeping_gpio_gate_ops = {
104 	.prepare = clk_sleeping_gpio_gate_prepare,
105 	.unprepare = clk_sleeping_gpio_gate_unprepare,
106 	.is_prepared = clk_sleeping_gpio_gate_is_prepared,
107 };
108 
109 /**
110  * DOC: basic clock multiplexer which can be controlled with a gpio output
111  * Traits of this clock:
112  * prepare - clk_prepare only ensures that parents are prepared
113  * rate - rate is only affected by parent switching.  No clk_set_rate support
114  * parent - parent is adjustable through clk_set_parent
115  */
116 
clk_gpio_mux_get_parent(struct clk_hw * hw)117 static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
118 {
119 	struct clk_gpio *clk = to_clk_gpio(hw);
120 
121 	return gpiod_get_value_cansleep(clk->gpiod);
122 }
123 
clk_gpio_mux_set_parent(struct clk_hw * hw,u8 index)124 static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
125 {
126 	struct clk_gpio *clk = to_clk_gpio(hw);
127 
128 	gpiod_set_value_cansleep(clk->gpiod, index);
129 
130 	return 0;
131 }
132 
133 static const struct clk_ops clk_gpio_mux_ops = {
134 	.get_parent = clk_gpio_mux_get_parent,
135 	.set_parent = clk_gpio_mux_set_parent,
136 	.determine_rate = __clk_mux_determine_rate,
137 };
138 
clk_register_gpio(struct device * dev,u8 num_parents,struct gpio_desc * gpiod,const struct clk_ops * clk_gpio_ops)139 static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
140 					struct gpio_desc *gpiod,
141 					const struct clk_ops *clk_gpio_ops)
142 {
143 	struct clk_gpio *clk_gpio;
144 	struct clk_hw *hw;
145 	struct clk_init_data init = {};
146 	int err;
147 	const struct clk_parent_data gpio_parent_data[] = {
148 		{ .index = 0 },
149 		{ .index = 1 },
150 	};
151 
152 	clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio),	GFP_KERNEL);
153 	if (!clk_gpio)
154 		return ERR_PTR(-ENOMEM);
155 
156 	init.name = dev->of_node->name;
157 	init.ops = clk_gpio_ops;
158 	init.parent_data = gpio_parent_data;
159 	init.num_parents = num_parents;
160 	init.flags = CLK_SET_RATE_PARENT;
161 
162 	clk_gpio->gpiod = gpiod;
163 	clk_gpio->hw.init = &init;
164 
165 	hw = &clk_gpio->hw;
166 	err = devm_clk_hw_register(dev, hw);
167 	if (err)
168 		return ERR_PTR(err);
169 
170 	return hw;
171 }
172 
clk_hw_register_gpio_gate(struct device * dev,int num_parents,struct gpio_desc * gpiod)173 static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
174 						int num_parents,
175 						struct gpio_desc *gpiod)
176 {
177 	const struct clk_ops *ops;
178 
179 	if (gpiod_cansleep(gpiod))
180 		ops = &clk_sleeping_gpio_gate_ops;
181 	else
182 		ops = &clk_gpio_gate_ops;
183 
184 	return clk_register_gpio(dev, num_parents, gpiod, ops);
185 }
186 
clk_hw_register_gpio_mux(struct device * dev,struct gpio_desc * gpiod)187 static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
188 					       struct gpio_desc *gpiod)
189 {
190 	return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
191 }
192 
gpio_clk_driver_probe(struct platform_device * pdev)193 static int gpio_clk_driver_probe(struct platform_device *pdev)
194 {
195 	struct device *dev = &pdev->dev;
196 	struct device_node *node = dev->of_node;
197 	const char *gpio_name;
198 	unsigned int num_parents;
199 	struct gpio_desc *gpiod;
200 	struct clk_hw *hw;
201 	bool is_mux;
202 	int ret;
203 
204 	is_mux = of_device_is_compatible(node, "gpio-mux-clock");
205 
206 	num_parents = of_clk_get_parent_count(node);
207 	if (is_mux && num_parents != 2) {
208 		dev_err(dev, "mux-clock must have 2 parents\n");
209 		return -EINVAL;
210 	}
211 
212 	gpio_name = is_mux ? "select" : "enable";
213 	gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
214 	if (IS_ERR(gpiod)) {
215 		ret = PTR_ERR(gpiod);
216 		if (ret == -EPROBE_DEFER)
217 			pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
218 					node, __func__);
219 		else
220 			pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
221 					node, __func__,
222 					gpio_name);
223 		return ret;
224 	}
225 
226 	if (is_mux)
227 		hw = clk_hw_register_gpio_mux(dev, gpiod);
228 	else
229 		hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
230 	if (IS_ERR(hw))
231 		return PTR_ERR(hw);
232 
233 	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
234 }
235 
236 static const struct of_device_id gpio_clk_match_table[] = {
237 	{ .compatible = "gpio-mux-clock" },
238 	{ .compatible = "gpio-gate-clock" },
239 	{ }
240 };
241 
242 static struct platform_driver gpio_clk_driver = {
243 	.probe		= gpio_clk_driver_probe,
244 	.driver		= {
245 		.name	= "gpio-clk",
246 		.of_match_table = gpio_clk_match_table,
247 	},
248 };
249 builtin_platform_driver(gpio_clk_driver);
250