drivers/pwm/pwm-imx-util.c

   1 /*
   2  * (C) Copyright 2014
   3  * Heiko Schocher, DENX Software Engineering, hs@denx.de.
   4  *
   5  * Basic support for the pwm modul on imx6.
   6  *
   7  * Based on linux:drivers/pwm/pwm-imx.c
   8  * from
   9  * Sascha Hauer <s.hauer@pengutronix.de>
  10  *
  11  * SPDX-License-Identifier:     GPL-2.0
  12  */
  13
  14 #include <common.h>
  15 #include <div64.h>
  16 #include <asm/arch/imx-regs.h>
  17
  18 /* pwm_id from 0..3 */
  19 struct pwm_regs *pwm_id_to_reg(int pwm_id)
  20 {
  21         switch (pwm_id) {
  22         case 0:
  23                 return (struct pwm_regs *)PWM1_BASE_ADDR;
  24                 break;
  25         case 1:
  26                 return (struct pwm_regs *)PWM2_BASE_ADDR;
  27                 break;
  28         case 2:
  29                 return (struct pwm_regs *)PWM3_BASE_ADDR;
  30                 break;
  31         case 3:
  32                 return (struct pwm_regs *)PWM4_BASE_ADDR;
  33                 break;
  34         default:
  35                 printf("unknown pwm_id: %d\n", pwm_id);
  36                 break;
  37         }
  38         return NULL;
  39 }
  40
  41 int pwm_imx_get_parms(int period_ns, int duty_ns, unsigned long *period_c,
  42                       unsigned long *duty_c, unsigned long *prescale)
  43 {
  44         unsigned long long c;
  45
  46         /*
  47          * we have not yet a clock framework for imx6, so add the clock
  48          * value here as a define. Replace it when we have the clock
  49          * framework.
  50          */
  51         c = CONFIG_IMX6_PWM_PER_CLK;
  52         c = c * period_ns;
  53         do_div(c, 1000000000);
  54         *period_c = c;
  55
  56         *prescale = *period_c / 0x10000 + 1;
  57
  58         *period_c /= *prescale;
  59         c = (unsigned long long)(*period_c * duty_ns);
  60         do_div(c, period_ns);
  61         *duty_c = c;
  62
  63         /*
  64          * according to imx pwm RM, the real period value should be
  65          * PERIOD value in PWMPR plus 2.
  66          */
  67         if (*period_c > 2)
  68                 *period_c -= 2;
  69         else
  70                 *period_c = 0;
  71
  72         return 0;
  73 }