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imx233: enhance pwm
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
This commit is contained in:
Amaury Pouly
parent
f5ac658d16
commit
f8d2984875
4 changed files with 99 additions and 20 deletions
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@ -28,10 +28,8 @@
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void _backlight_set_brightness(int brightness)
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{
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imx233_pwm_setup_channel(4, 1024, BV_PWM_PERIODn_CDIV__DIV_1,
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0, BV_PWM_PERIODn_ACTIVE_STATE__1,
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(brightness * 1024) / 100, BV_PWM_PERIODn_INACTIVE_STATE__0);
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imx233_pwm_enable_channel(4, true);
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imx233_pwm_setup_simple(4, 24000, brightness);
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imx233_pwm_enable(4, true);
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}
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bool _backlight_init(void)
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@ -29,10 +29,8 @@
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void _backlight_set_brightness(int brightness)
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{
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imx233_pwm_setup_channel(2, 1024, BV_PWM_PERIODn_CDIV__DIV_1,
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0, BV_PWM_PERIODn_ACTIVE_STATE__1,
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(brightness * 1024) / 100, BV_PWM_PERIODn_INACTIVE_STATE__0);
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imx233_pwm_enable_channel(2, true);
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imx233_pwm_setup_simple(2, 24000, brightness);
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imx233_pwm_enable(2, true);
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}
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bool _backlight_init(void)
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@ -18,22 +18,32 @@
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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_channel_enable(int channel)
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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_channel(int channel, bool enable)
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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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@ -41,13 +51,13 @@ void imx233_pwm_enable_channel(int channel, bool enable)
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BF_CLR(PWM_CTRL, PWMx_ENABLE(channel));
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}
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void imx233_pwm_setup_channel(int channel, int period, int cdiv, int active,
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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_channel_enable(channel);
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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(channel, false);
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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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@ -56,5 +66,65 @@ void imx233_pwm_setup_channel(int channel, int period, int cdiv, int active,
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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(channel, enable);
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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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@ -33,13 +33,26 @@
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#define IMX233_PWM_NR_CHANNELS 5
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#define IMX233_PWM_PIN_BANK(channel) 1
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#define IMX233_PWM_PIN(channel) (26 + (channel))
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void imx233_pwm_init(void);
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void imx233_pwm_setup_channel(int channel, int period, int cdiv, int active,
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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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void imx233_pwm_enable_channel(int channel, bool enable);
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bool imx233_pwm_is_channel_enable(int channel);
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/* helper function to compute adequate divisor and period, given a minimum
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* period resolution (for active/inactive) */
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void imx233_pwm_lookup_freq(int freq, int min_period, int *period, int *cdiv);
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/* simple setup with active 1, inactive 0, duty cycle in percent */
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void imx233_pwm_setup_simple(int channel, int freq, int duty_cycle);
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void imx233_pwm_enable(int channel, bool enable);
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bool imx233_pwm_is_enabled(int channel);
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struct imx233_pwm_info_t
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{
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bool enabled;
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int cdiv;
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int period;
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int inactive, active;
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char inactive_state, active_state; // '0', '1' or 'Z'
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};
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struct imx233_pwm_info_t imx233_pwm_get_info(int channel);
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#endif /* __PWM_IMX233_H__ */
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