1/*
  2 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
  3 *
  4 * Authors:
  5 *    Jyri Sarha <jsarha@ti.com>
  6 *    Sergej Sawazki <ce3a@gmx.de>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 *
 12 * Gpio controlled clock implementation
 13 */
 14
 15#include <linux/clk-provider.h>
 16#include <linux/export.h>
 17#include <linux/slab.h>
 18#include <linux/gpio.h>
 19#include <linux/gpio/consumer.h>
 20#include <linux/of_gpio.h>
 21#include <linux/err.h>
 22#include <linux/device.h>
 23#include <linux/platform_device.h>
 24#include <linux/of_device.h>
 25
 26/**
 27 * DOC: basic gpio gated clock which can be enabled and disabled
 28 *      with gpio output
 29 * Traits of this clock:
 30 * prepare - clk_(un)prepare only ensures parent is (un)prepared
 31 * enable - clk_enable and clk_disable are functional & control gpio
 32 * rate - inherits rate from parent.  No clk_set_rate support
 33 * parent - fixed parent.  No clk_set_parent support
 34 */
 35
 36static int clk_gpio_gate_enable(struct clk_hw *hw)
 37{
 38	struct clk_gpio *clk = to_clk_gpio(hw);
 39
 40	gpiod_set_value(clk->gpiod, 1);
 41
 42	return 0;
 43}
 44
 45static void clk_gpio_gate_disable(struct clk_hw *hw)
 46{
 47	struct clk_gpio *clk = to_clk_gpio(hw);
 48
 49	gpiod_set_value(clk->gpiod, 0);
 50}
 51
 52static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
 53{
 54	struct clk_gpio *clk = to_clk_gpio(hw);
 55
 56	return gpiod_get_value(clk->gpiod);
 57}
 58
 59const struct clk_ops clk_gpio_gate_ops = {
 60	.enable = clk_gpio_gate_enable,
 61	.disable = clk_gpio_gate_disable,
 62	.is_enabled = clk_gpio_gate_is_enabled,
 63};
 64EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
 65
 66/**
 67 * DOC: basic clock multiplexer which can be controlled with a gpio output
 68 * Traits of this clock:
 69 * prepare - clk_prepare only ensures that parents are prepared
 70 * rate - rate is only affected by parent switching.  No clk_set_rate support
 71 * parent - parent is adjustable through clk_set_parent
 72 */
 73
 74static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
 75{
 76	struct clk_gpio *clk = to_clk_gpio(hw);
 77
 78	return gpiod_get_value(clk->gpiod);
 79}
 80
 81static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
 82{
 83	struct clk_gpio *clk = to_clk_gpio(hw);
 84
 85	gpiod_set_value(clk->gpiod, index);
 86
 87	return 0;
 88}
 89
 90const struct clk_ops clk_gpio_mux_ops = {
 91	.get_parent = clk_gpio_mux_get_parent,
 92	.set_parent = clk_gpio_mux_set_parent,
 93	.determine_rate = __clk_mux_determine_rate,
 94};
 95EXPORT_SYMBOL_GPL(clk_gpio_mux_ops);
 96
 97static struct clk_hw *clk_register_gpio(struct device *dev, const char *name,
 98		const char * const *parent_names, u8 num_parents, unsigned gpio,
 99		bool active_low, unsigned long flags,
100		const struct clk_ops *clk_gpio_ops)
101{
102	struct clk_gpio *clk_gpio;
103	struct clk_hw *hw;
104	struct clk_init_data init = {};
105	unsigned long gpio_flags;
106	int err;
107
108	if (dev)
109		clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio),	GFP_KERNEL);
110	else
111		clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL);
112
113	if (!clk_gpio)
114		return ERR_PTR(-ENOMEM);
115
116	if (active_low)
117		gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH;
118	else
119		gpio_flags = GPIOF_OUT_INIT_LOW;
120
121	if (dev)
122		err = devm_gpio_request_one(dev, gpio, gpio_flags, name);
123	else
124		err = gpio_request_one(gpio, gpio_flags, name);
125	if (err) {
126		if (err != -EPROBE_DEFER)
127			pr_err("%s: %s: Error requesting clock control gpio %u\n",
128					__func__, name, gpio);
129		if (!dev)
130			kfree(clk_gpio);
131
132		return ERR_PTR(err);
133	}
134
135	init.name = name;
136	init.ops = clk_gpio_ops;
137	init.flags = flags | CLK_IS_BASIC;
138	init.parent_names = parent_names;
139	init.num_parents = num_parents;
140
141	clk_gpio->gpiod = gpio_to_desc(gpio);
142	clk_gpio->hw.init = &init;
143
144	hw = &clk_gpio->hw;
145	if (dev)
146		err = devm_clk_hw_register(dev, hw);
147	else
148		err = clk_hw_register(NULL, hw);
149
150	if (!err)
151		return hw;
152
153	if (!dev) {
154		gpiod_put(clk_gpio->gpiod);
155		kfree(clk_gpio);
156	}
157
158	return ERR_PTR(err);
159}
160
161/**
162 * clk_hw_register_gpio_gate - register a gpio clock gate with the clock
163 * framework
164 * @dev: device that is registering this clock
165 * @name: name of this clock
166 * @parent_name: name of this clock's parent
167 * @gpio: gpio number to gate this clock
168 * @active_low: true if gpio should be set to 0 to enable clock
169 * @flags: clock flags
170 */
171struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, const char *name,
172		const char *parent_name, unsigned gpio, bool active_low,
173		unsigned long flags)
174{
175	return clk_register_gpio(dev, name,
176			(parent_name ? &parent_name : NULL),
177			(parent_name ? 1 : 0), gpio, active_low, flags,
178			&clk_gpio_gate_ops);
179}
180EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate);
181
182struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
183		const char *parent_name, unsigned gpio, bool active_low,
184		unsigned long flags)
185{
186	struct clk_hw *hw;
187
188	hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpio, active_low,
189				       flags);
190	if (IS_ERR(hw))
191		return ERR_CAST(hw);
192	return hw->clk;
193}
194EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
195
196/**
197 * clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework
198 * @dev: device that is registering this clock
199 * @name: name of this clock
200 * @parent_names: names of this clock's parents
201 * @num_parents: number of parents listed in @parent_names
202 * @gpio: gpio number to gate this clock
203 * @active_low: true if gpio should be set to 0 to enable clock
204 * @flags: clock flags
205 */
206struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name,
207		const char * const *parent_names, u8 num_parents, unsigned gpio,
208		bool active_low, unsigned long flags)
209{
210	if (num_parents != 2) {
211		pr_err("mux-clock %s must have 2 parents\n", name);
212		return ERR_PTR(-EINVAL);
213	}
214
215	return clk_register_gpio(dev, name, parent_names, num_parents,
216			gpio, active_low, flags, &clk_gpio_mux_ops);
217}
218EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux);
219
220struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
221		const char * const *parent_names, u8 num_parents, unsigned gpio,
222		bool active_low, unsigned long flags)
223{
224	struct clk_hw *hw;
225
226	hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents,
227			gpio, active_low, flags);
228	if (IS_ERR(hw))
229		return ERR_CAST(hw);
230	return hw->clk;
231}
232EXPORT_SYMBOL_GPL(clk_register_gpio_mux);
233
234static int gpio_clk_driver_probe(struct platform_device *pdev)
235{
236	struct device_node *node = pdev->dev.of_node;
237	const char **parent_names, *gpio_name;
238	unsigned int num_parents;
239	int gpio;
240	enum of_gpio_flags of_flags;
241	struct clk *clk;
242	bool active_low, is_mux;
243
244	num_parents = of_clk_get_parent_count(node);
245	if (num_parents) {
246		parent_names = devm_kcalloc(&pdev->dev, num_parents,
247					    sizeof(char *), GFP_KERNEL);
248		if (!parent_names)
249			return -ENOMEM;
250
251		of_clk_parent_fill(node, parent_names, num_parents);
252	} else {
253		parent_names = NULL;
254	}
255
256	is_mux = of_device_is_compatible(node, "gpio-mux-clock");
257
258	gpio_name = is_mux ? "select-gpios" : "enable-gpios";
259	gpio = of_get_named_gpio_flags(node, gpio_name, 0, &of_flags);
260	if (gpio < 0) {
261		if (gpio == -EPROBE_DEFER)
262			pr_debug("%s: %s: GPIOs not yet available, retry later\n",
263					node->name, __func__);
264		else
265			pr_err("%s: %s: Can't get '%s' DT property\n",
266					node->name, __func__,
267					gpio_name);
268		return gpio;
269	}
270
271	active_low = of_flags & OF_GPIO_ACTIVE_LOW;
272
273	if (is_mux)
274		clk = clk_register_gpio_mux(&pdev->dev, node->name,
275				parent_names, num_parents, gpio, active_low, 0);
276	else
277		clk = clk_register_gpio_gate(&pdev->dev, node->name,
278				parent_names ?  parent_names[0] : NULL, gpio,
279				active_low, 0);
280	if (IS_ERR(clk))
281		return PTR_ERR(clk);
282
283	return of_clk_add_provider(node, of_clk_src_simple_get, clk);
284}
285
286static const struct of_device_id gpio_clk_match_table[] = {
287	{ .compatible = "gpio-mux-clock" },
288	{ .compatible = "gpio-gate-clock" },
289	{ }
290};
291
292static struct platform_driver gpio_clk_driver = {
293	.probe		= gpio_clk_driver_probe,
294	.driver		= {
295		.name	= "gpio-clk",
296		.of_match_table = gpio_clk_match_table,
297	},
298};
299builtin_platform_driver(gpio_clk_driver);