MIPS: JZ4740: Add PWM support
[sfrench/cifs-2.6.git] / arch / mips / jz4740 / pwm.c
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/kernel.h>
17
18 #include <linux/clk.h>
19 #include <linux/err.h>
20 #include <linux/pwm.h>
21 #include <linux/gpio.h>
22
23 #include <asm/mach-jz4740/gpio.h>
24 #include "timer.h"
25
26 static struct clk *jz4740_pwm_clk;
27
28 DEFINE_MUTEX(jz4740_pwm_mutex);
29
30 struct pwm_device {
31         unsigned int id;
32         unsigned int gpio;
33         bool used;
34 };
35
36 static struct pwm_device jz4740_pwm_list[] = {
37         { 2, JZ_GPIO_PWM2, false },
38         { 3, JZ_GPIO_PWM3, false },
39         { 4, JZ_GPIO_PWM4, false },
40         { 5, JZ_GPIO_PWM5, false },
41         { 6, JZ_GPIO_PWM6, false },
42         { 7, JZ_GPIO_PWM7, false },
43 };
44
45 struct pwm_device *pwm_request(int id, const char *label)
46 {
47         int ret = 0;
48         struct pwm_device *pwm;
49
50         if (id < 2 || id > 7 || !jz4740_pwm_clk)
51                 return ERR_PTR(-ENODEV);
52
53         mutex_lock(&jz4740_pwm_mutex);
54
55         pwm = &jz4740_pwm_list[id - 2];
56         if (pwm->used)
57                 ret = -EBUSY;
58         else
59                 pwm->used = true;
60
61         mutex_unlock(&jz4740_pwm_mutex);
62
63         if (ret)
64                 return ERR_PTR(ret);
65
66         ret = gpio_request(pwm->gpio, label);
67
68         if (ret) {
69                 printk(KERN_ERR "Failed to request pwm gpio: %d\n", ret);
70                 pwm->used = false;
71                 return ERR_PTR(ret);
72         }
73
74         jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_PWM);
75
76         jz4740_timer_start(id);
77
78         return pwm;
79 }
80
81 void pwm_free(struct pwm_device *pwm)
82 {
83         pwm_disable(pwm);
84         jz4740_timer_set_ctrl(pwm->id, 0);
85
86         jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_NONE);
87         gpio_free(pwm->gpio);
88
89         jz4740_timer_stop(pwm->id);
90
91         pwm->used = false;
92 }
93
94 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
95 {
96         unsigned long long tmp;
97         unsigned long period, duty;
98         unsigned int prescaler = 0;
99         unsigned int id = pwm->id;
100         uint16_t ctrl;
101         bool is_enabled;
102
103         if (duty_ns < 0 || duty_ns > period_ns)
104                 return -EINVAL;
105
106         tmp = (unsigned long long)clk_get_rate(jz4740_pwm_clk) * period_ns;
107         do_div(tmp, 1000000000);
108         period = tmp;
109
110         while (period > 0xffff && prescaler < 6) {
111                 period >>= 2;
112                 ++prescaler;
113         }
114
115         if (prescaler == 6)
116                 return -EINVAL;
117
118         tmp = (unsigned long long)period * duty_ns;
119         do_div(tmp, period_ns);
120         duty = period - tmp;
121
122         if (duty >= period)
123                 duty = period - 1;
124
125         is_enabled = jz4740_timer_is_enabled(id);
126         if (is_enabled)
127                 pwm_disable(pwm);
128
129         jz4740_timer_set_count(id, 0);
130         jz4740_timer_set_duty(id, duty);
131         jz4740_timer_set_period(id, period);
132
133         ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
134                 JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
135
136         jz4740_timer_set_ctrl(id, ctrl);
137
138         if (is_enabled)
139                 pwm_enable(pwm);
140
141         return 0;
142 }
143
144 int pwm_enable(struct pwm_device *pwm)
145 {
146         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
147
148         ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
149         jz4740_timer_set_ctrl(pwm->id, ctrl);
150         jz4740_timer_enable(pwm->id);
151
152         return 0;
153 }
154
155 void pwm_disable(struct pwm_device *pwm)
156 {
157         uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
158
159         ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
160         jz4740_timer_disable(pwm->id);
161         jz4740_timer_set_ctrl(pwm->id, ctrl);
162 }
163
164 static int __init jz4740_pwm_init(void)
165 {
166         int ret = 0;
167
168         jz4740_pwm_clk = clk_get(NULL, "ext");
169
170         if (IS_ERR(jz4740_pwm_clk)) {
171                 ret = PTR_ERR(jz4740_pwm_clk);
172                 jz4740_pwm_clk = NULL;
173         }
174
175         return ret;
176 }
177 subsys_initcall(jz4740_pwm_init);