f8d2984875
The current pwm interface is too low-level. Introduce a higher level setup function which directly computes the parameters from the required frequency. Change-Id: Ie95c7522e9f42492fe872203f4cab46770a9649a
130 lines
4.6 KiB
C
130 lines
4.6 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2011 by Amaury Pouly
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "stdlib.h"
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#include "string.h"
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#include "pwm-imx233.h"
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#include "clkctrl-imx233.h"
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#include "pinctrl-imx233.h"
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/* list of divisors + register value by increasing order of divisors */
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static int pwm_cdiv_table[] =
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{
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#define DIV(d) [BV_PWM_PERIODn_CDIV__DIV_##d] = d
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DIV(1), DIV(2), DIV(4), DIV(8), DIV(16), DIV(64), DIV(256), DIV(1024)
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#undef DIV
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};
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void imx233_pwm_init(void)
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{
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imx233_reset_block(&HW_PWM_CTRL);
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imx233_clkctrl_enable(CLK_PWM, true);
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}
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bool imx233_pwm_is_enabled(int channel)
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{
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return BF_RD(PWM_CTRL, PWMx_ENABLE(channel));
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}
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void imx233_pwm_enable(int channel, bool enable)
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{
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if(enable)
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BF_SET(PWM_CTRL, PWMx_ENABLE(channel));
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else
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BF_CLR(PWM_CTRL, PWMx_ENABLE(channel));
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}
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void imx233_pwm_setup(int channel, int period, int cdiv, int active,
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int active_state, int inactive, int inactive_state)
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{
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/* stop */
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bool enable = imx233_pwm_is_enabled(channel);
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if(enable)
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imx233_pwm_enable(channel, false);
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/* setup pin */
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imx233_pinctrl_setup_vpin(VPIN_PWM(channel), "pwm", PINCTRL_DRIVE_4mA, false);
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/* watch the order ! active THEN period
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* NOTE: the register value is period-1 */
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HW_PWM_ACTIVEn(channel) = BF_OR2(PWM_ACTIVEn, ACTIVE(active), INACTIVE(inactive));
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HW_PWM_PERIODn(channel) = BF_OR4(PWM_PERIODn, PERIOD(period - 1),
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ACTIVE_STATE(active_state), INACTIVE_STATE(inactive_state), CDIV(cdiv));
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/* restore */
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imx233_pwm_enable(channel, enable);
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}
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void imx233_pwm_lookup_freq(int freq, int min_period, int *out_period, int *out_cdiv)
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{
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/* find best divisor */
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int best_freq_err = freq;
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int xtal_freq = imx233_clkctrl_get_freq(CLK_XTAL) * 1000;
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for(unsigned cdiv = 0; cdiv < ARRAYLEN(pwm_cdiv_table); cdiv++)
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{
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/* compute best period (we have two rounding choices) */
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int p = xtal_freq / (pwm_cdiv_table[cdiv] * freq);
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for(int period = p; period <= p + 1; period++)
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{
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/* avoid forbidden periods */
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if(p < min_period || p > IMX233_PWM_MAX_PERIOD)
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continue;
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/* compute actual frequency and compare with best obtained so far */
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int f = xtal_freq / (pwm_cdiv_table[cdiv] * period);
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if(ABS(freq - f) <= best_freq_err)
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{
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*out_period = period;
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*out_cdiv = cdiv;
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best_freq_err = ABS(freq - f);
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}
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}
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}
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}
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void imx233_pwm_setup_simple(int channel, int freq, int duty_cycle)
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{
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int period, cdiv;
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imx233_pwm_lookup_freq(freq, 100, &period, &cdiv);
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int inactive = (period * duty_cycle) / 100;
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imx233_pwm_setup(channel, period, cdiv, 0, BV_PWM_PERIODn_ACTIVE_STATE__1,
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inactive, BV_PWM_PERIODn_INACTIVE_STATE__0);
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}
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struct imx233_pwm_info_t imx233_pwm_get_info(int channel)
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{
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#define ENTRY(mode, name, val) [BV_PWM_PERIODn_##mode##_STATE__##name] = val
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static char active_state[] =
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{
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ENTRY(ACTIVE, 0, '0'), ENTRY(ACTIVE, 1, '1'), ENTRY(ACTIVE, HI_Z, 'Z')
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};
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static char inactive_state[] =
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{
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ENTRY(INACTIVE, 0, '0'), ENTRY(INACTIVE, 1, '1'), ENTRY(INACTIVE, HI_Z, 'Z')
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};
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#undef ENTRY
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struct imx233_pwm_info_t info;
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memset(&info, 0, sizeof(info));
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info.enabled = imx233_pwm_is_enabled(channel);
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info.cdiv = pwm_cdiv_table[BF_RDn(PWM_PERIODn, channel, CDIV)];
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info.period = BF_RDn(PWM_PERIODn, channel, PERIOD) + 1;
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info.active = BF_RDn(PWM_ACTIVEn, channel, ACTIVE);
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info.inactive = BF_RDn(PWM_ACTIVEn, channel, INACTIVE);
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info.active_state = active_state[BF_RDn(PWM_PERIODn, channel, ACTIVE_STATE)];
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info.inactive_state = inactive_state[BF_RDn(PWM_PERIODn, channel, INACTIVE_STATE)];
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return info;
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}
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