Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

Linux/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                 .owner = THIS_MODULE,
198         },
199         .probe = jz4740_pwm_probe,
200         .remove = jz4740_pwm_remove,
201 };
202 module_platform_driver(jz4740_pwm_driver);
203 
204 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
205 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
206 MODULE_ALIAS("platform:jz4740-pwm");
207 MODULE_LICENSE("GPL");
208 

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