arch/blackfin/kernel/pwm.c

   1 /*
   2  * Blackfin Pulse Width Modulation (PWM) core
   3  *
   4  * Copyright (c) 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/pwm.h>
  11 #include <linux/slab.h>
  12
  13 #include <asm/gptimers.h>
  14 #include <asm/portmux.h>
  15
  16 struct pwm_device {
  17         unsigned id;
  18         unsigned short pin;
  19 };
  20
  21 static const unsigned short pwm_to_gptimer_per[] = {
  22         P_TMR0, P_TMR1, P_TMR2, P_TMR3, P_TMR4, P_TMR5,
  23         P_TMR6, P_TMR7, P_TMR8, P_TMR9, P_TMR10, P_TMR11,
  24 };
  25
  26 struct pwm_device *pwm_request(int pwm_id, const char *label)
  27 {
  28         struct pwm_device *pwm;
  29         int ret;
  30
  31         /* XXX: pwm_id really should be unsigned */
  32         if (pwm_id < 0)
  33                 return NULL;
  34
  35         pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
  36         if (!pwm)
  37                 return pwm;
  38
  39         pwm->id = pwm_id;
  40         if (pwm->id >= ARRAY_SIZE(pwm_to_gptimer_per))
  41                 goto err;
  42
  43         pwm->pin = pwm_to_gptimer_per[pwm->id];
  44         ret = peripheral_request(pwm->pin, label);
  45         if (ret)
  46                 goto err;
  47
  48         return pwm;
  49  err:
  50         kfree(pwm);
  51         return NULL;
  52 }
  53 EXPORT_SYMBOL(pwm_request);
  54
  55 void pwm_free(struct pwm_device *pwm)
  56 {
  57         peripheral_free(pwm->pin);
  58         kfree(pwm);
  59 }
  60 EXPORT_SYMBOL(pwm_free);
  61
  62 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  63 {
  64         unsigned long period, duty;
  65         unsigned long long val;
  66
  67         if (duty_ns < 0 || duty_ns > period_ns)
  68                 return -EINVAL;
  69
  70         val = (unsigned long long)get_sclk() * period_ns;
  71         do_div(val, NSEC_PER_SEC);
  72         period = val;
  73
  74         val = (unsigned long long)period * duty_ns;
  75         do_div(val, period_ns);
  76         duty = period - val;
  77
  78         if (duty >= period)
  79                 duty = period - 1;
  80
  81         set_gptimer_config(pwm->id, TIMER_MODE_PWM | TIMER_PERIOD_CNT);
  82         set_gptimer_pwidth(pwm->id, duty);
  83         set_gptimer_period(pwm->id, period);
  84
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(pwm_config);
  88
  89 int pwm_enable(struct pwm_device *pwm)
  90 {
  91         enable_gptimer(pwm->id);
  92         return 0;
  93 }
  94 EXPORT_SYMBOL(pwm_enable);
  95
  96 void pwm_disable(struct pwm_device *pwm)
  97 {
  98         disable_gptimer(pwm->id);
  99 }
 100 EXPORT_SYMBOL(pwm_disable);