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
pwm_request(int id,const char * label)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
pwm_free(struct pwm_device * pwm)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
pwm_config(struct pwm_device * pwm,int duty_ns,int period_ns)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
pwm_enable(struct pwm_device * pwm)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
pwm_disable(struct pwm_device * pwm)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
jz4740_pwm_init(void)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);
178