[go: nahoru, domu]
1/*
2 *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
3 *  JZ4740 platform PWM support
4 *
5 *  This program is free software; you can redistribute it and/or modify it
6 *  under  the terms of the GNU General  Public License as published by the
7 *  Free Software Foundation;  either version 2 of the License, or (at your
8 *  option) any later version.
9 *
10 *  You should have received a copy of the GNU General Public License along
11 *  with this program; if not, write to the Free Software Foundation, Inc.,
12 *  675 Mass Ave, Cambridge, MA 02139, USA.
13 *
14 */
15
16#include <linux/clk.h>
17#include <linux/err.h>
18#include <linux/gpio.h>
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/platform_device.h>
22#include <linux/pwm.h>
23
24#include <asm/mach-jz4740/gpio.h>
25#include <asm/mach-jz4740/timer.h>
26
27#define NUM_PWM 8
28
29static const unsigned int jz4740_pwm_gpio_list[NUM_PWM] = {
30	JZ_GPIO_PWM0,
31	JZ_GPIO_PWM1,
32	JZ_GPIO_PWM2,
33	JZ_GPIO_PWM3,
34	JZ_GPIO_PWM4,
35	JZ_GPIO_PWM5,
36	JZ_GPIO_PWM6,
37	JZ_GPIO_PWM7,
38};
39
40struct jz4740_pwm_chip {
41	struct pwm_chip chip;
42	struct clk *clk;
43};
44
45static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
46{
47	return container_of(chip, struct jz4740_pwm_chip, chip);
48}
49
50static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
51{
52	unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
53	int ret;
54
55	/*
56	 * Timers 0 and 1 are used for system tasks, so they are unavailable
57	 * for use as PWMs.
58	 */
59	if (pwm->hwpwm < 2)
60		return -EBUSY;
61
62	ret = gpio_request(gpio, pwm->label);
63	if (ret) {
64		dev_err(chip->dev, "Failed to request GPIO#%u for PWM: %d\n",
65			gpio, ret);
66		return ret;
67	}
68
69	jz_gpio_set_function(gpio, JZ_GPIO_FUNC_PWM);
70
71	jz4740_timer_start(pwm->hwpwm);
72
73	return 0;
74}
75
76static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
77{
78	unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
79
80	jz4740_timer_set_ctrl(pwm->hwpwm, 0);
81
82	jz_gpio_set_function(gpio, JZ_GPIO_FUNC_NONE);
83	gpio_free(gpio);
84
85	jz4740_timer_stop(pwm->hwpwm);
86}
87
88static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
89{
90	uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
91
92	ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
93	jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
94	jz4740_timer_enable(pwm->hwpwm);
95
96	return 0;
97}
98
99static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
100{
101	uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
102
103	ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
104	jz4740_timer_disable(pwm->hwpwm);
105	jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
106}
107
108static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
109			     int duty_ns, int period_ns)
110{
111	struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
112	unsigned long long tmp;
113	unsigned long period, duty;
114	unsigned int prescaler = 0;
115	uint16_t ctrl;
116	bool is_enabled;
117
118	tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
119	do_div(tmp, 1000000000);
120	period = tmp;
121
122	while (period > 0xffff && prescaler < 6) {
123		period >>= 2;
124		++prescaler;
125	}
126
127	if (prescaler == 6)
128		return -EINVAL;
129
130	tmp = (unsigned long long)period * duty_ns;
131	do_div(tmp, period_ns);
132	duty = period - tmp;
133
134	if (duty >= period)
135		duty = period - 1;
136
137	is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
138	if (is_enabled)
139		jz4740_pwm_disable(chip, pwm);
140
141	jz4740_timer_set_count(pwm->hwpwm, 0);
142	jz4740_timer_set_duty(pwm->hwpwm, duty);
143	jz4740_timer_set_period(pwm->hwpwm, period);
144
145	ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
146		JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
147
148	jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
149
150	if (is_enabled)
151		jz4740_pwm_enable(chip, pwm);
152
153	return 0;
154}
155
156static const struct pwm_ops jz4740_pwm_ops = {
157	.request = jz4740_pwm_request,
158	.free = jz4740_pwm_free,
159	.config = jz4740_pwm_config,
160	.enable = jz4740_pwm_enable,
161	.disable = jz4740_pwm_disable,
162	.owner = THIS_MODULE,
163};
164
165static int jz4740_pwm_probe(struct platform_device *pdev)
166{
167	struct jz4740_pwm_chip *jz4740;
168
169	jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL);
170	if (!jz4740)
171		return -ENOMEM;
172
173	jz4740->clk = devm_clk_get(&pdev->dev, "ext");
174	if (IS_ERR(jz4740->clk))
175		return PTR_ERR(jz4740->clk);
176
177	jz4740->chip.dev = &pdev->dev;
178	jz4740->chip.ops = &jz4740_pwm_ops;
179	jz4740->chip.npwm = NUM_PWM;
180	jz4740->chip.base = -1;
181
182	platform_set_drvdata(pdev, jz4740);
183
184	return pwmchip_add(&jz4740->chip);
185}
186
187static int jz4740_pwm_remove(struct platform_device *pdev)
188{
189	struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev);
190
191	return pwmchip_remove(&jz4740->chip);
192}
193
194static struct platform_driver jz4740_pwm_driver = {
195	.driver = {
196		.name = "jz4740-pwm",
197		.owner = THIS_MODULE,
198	},
199	.probe = jz4740_pwm_probe,
200	.remove = jz4740_pwm_remove,
201};
202module_platform_driver(jz4740_pwm_driver);
203
204MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
205MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
206MODULE_ALIAS("platform:jz4740-pwm");
207MODULE_LICENSE("GPL");
208