GNU Linux-libre 4.9.326-gnu1
[releases.git] / drivers / pwm / pwm-jz4740.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/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
29 static 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
40 struct jz4740_pwm_chip {
41         struct pwm_chip chip;
42         struct clk *clk;
43 };
44
45 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
46 {
47         return container_of(chip, struct jz4740_pwm_chip, chip);
48 }
49
50 static 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
76 static 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
88 static 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
99 static 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
108 static 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
156 static 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
165 static 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
187 static 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
194 static struct platform_driver jz4740_pwm_driver = {
195         .driver = {
196                 .name = "jz4740-pwm",
197         },
198         .probe = jz4740_pwm_probe,
199         .remove = jz4740_pwm_remove,
200 };
201 module_platform_driver(jz4740_pwm_driver);
202
203 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
204 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
205 MODULE_ALIAS("platform:jz4740-pwm");
206 MODULE_LICENSE("GPL");