diff options
author | Amaury Pouly <amaury.pouly@gmail.com> | 2013-06-16 20:15:32 +0200 |
---|---|---|
committer | Amaury Pouly <amaury.pouly@gmail.com> | 2013-06-17 00:29:24 +0200 |
commit | f8d298487596fd48366ab9444dfbc85d705b7a29 (patch) | |
tree | a32dd3cc676f41eb414a2604efb34437938245f5 | |
parent | f5ac658d160d11880c2affa9c5b669404c4fe207 (diff) | |
download | rockbox-f8d2984.tar.gz rockbox-f8d2984.zip |
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
4 files changed, 99 insertions, 20 deletions
diff --git a/firmware/target/arm/imx233/creative-zenxfi2/backlight-zenxfi2.c b/firmware/target/arm/imx233/creative-zenxfi2/backlight-zenxfi2.c index 3322098fa2..b01dc36063 100644 --- a/firmware/target/arm/imx233/creative-zenxfi2/backlight-zenxfi2.c +++ b/firmware/target/arm/imx233/creative-zenxfi2/backlight-zenxfi2.c @@ -28,10 +28,8 @@ void _backlight_set_brightness(int brightness) { - imx233_pwm_setup_channel(4, 1024, BV_PWM_PERIODn_CDIV__DIV_1, - 0, BV_PWM_PERIODn_ACTIVE_STATE__1, - (brightness * 1024) / 100, BV_PWM_PERIODn_INACTIVE_STATE__0); - imx233_pwm_enable_channel(4, true); + imx233_pwm_setup_simple(4, 24000, brightness); + imx233_pwm_enable(4, true); } bool _backlight_init(void) diff --git a/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c b/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c index 7b9327b695..7013696642 100644 --- a/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c +++ b/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c @@ -29,10 +29,8 @@ void _backlight_set_brightness(int brightness) { - imx233_pwm_setup_channel(2, 1024, BV_PWM_PERIODn_CDIV__DIV_1, - 0, BV_PWM_PERIODn_ACTIVE_STATE__1, - (brightness * 1024) / 100, BV_PWM_PERIODn_INACTIVE_STATE__0); - imx233_pwm_enable_channel(2, true); + imx233_pwm_setup_simple(2, 24000, brightness); + imx233_pwm_enable(2, true); } bool _backlight_init(void) diff --git a/firmware/target/arm/imx233/pwm-imx233.c b/firmware/target/arm/imx233/pwm-imx233.c index c434338a07..fb14fcb91f 100644 --- a/firmware/target/arm/imx233/pwm-imx233.c +++ b/firmware/target/arm/imx233/pwm-imx233.c @@ -18,22 +18,32 @@ * KIND, either express or implied. * ****************************************************************************/ +#include "stdlib.h" +#include "string.h" #include "pwm-imx233.h" #include "clkctrl-imx233.h" #include "pinctrl-imx233.h" +/* list of divisors + register value by increasing order of divisors */ +static int pwm_cdiv_table[] = +{ +#define DIV(d) [BV_PWM_PERIODn_CDIV__DIV_##d] = d + DIV(1), DIV(2), DIV(4), DIV(8), DIV(16), DIV(64), DIV(256), DIV(1024) +#undef DIV +}; + void imx233_pwm_init(void) { imx233_reset_block(&HW_PWM_CTRL); imx233_clkctrl_enable(CLK_PWM, true); } -bool imx233_pwm_is_channel_enable(int channel) +bool imx233_pwm_is_enabled(int channel) { return BF_RD(PWM_CTRL, PWMx_ENABLE(channel)); } -void imx233_pwm_enable_channel(int channel, bool enable) +void imx233_pwm_enable(int channel, bool enable) { if(enable) BF_SET(PWM_CTRL, PWMx_ENABLE(channel)); @@ -41,13 +51,13 @@ void imx233_pwm_enable_channel(int channel, bool enable) BF_CLR(PWM_CTRL, PWMx_ENABLE(channel)); } -void imx233_pwm_setup_channel(int channel, int period, int cdiv, int active, +void imx233_pwm_setup(int channel, int period, int cdiv, int active, int active_state, int inactive, int inactive_state) { /* stop */ - bool enable = imx233_pwm_is_channel_enable(channel); + bool enable = imx233_pwm_is_enabled(channel); if(enable) - imx233_pwm_enable_channel(channel, false); + imx233_pwm_enable(channel, false); /* setup pin */ imx233_pinctrl_setup_vpin(VPIN_PWM(channel), "pwm", PINCTRL_DRIVE_4mA, false); /* watch the order ! active THEN period @@ -56,5 +66,65 @@ void imx233_pwm_setup_channel(int channel, int period, int cdiv, int active, HW_PWM_PERIODn(channel) = BF_OR4(PWM_PERIODn, PERIOD(period - 1), ACTIVE_STATE(active_state), INACTIVE_STATE(inactive_state), CDIV(cdiv)); /* restore */ - imx233_pwm_enable_channel(channel, enable); + imx233_pwm_enable(channel, enable); +} + +void imx233_pwm_lookup_freq(int freq, int min_period, int *out_period, int *out_cdiv) +{ + /* find best divisor */ + int best_freq_err = freq; + int xtal_freq = imx233_clkctrl_get_freq(CLK_XTAL) * 1000; + + for(unsigned cdiv = 0; cdiv < ARRAYLEN(pwm_cdiv_table); cdiv++) + { + /* compute best period (we have two rounding choices) */ + int p = xtal_freq / (pwm_cdiv_table[cdiv] * freq); + for(int period = p; period <= p + 1; period++) + { + /* avoid forbidden periods */ + if(p < min_period || p > IMX233_PWM_MAX_PERIOD) + continue; + /* compute actual frequency and compare with best obtained so far */ + int f = xtal_freq / (pwm_cdiv_table[cdiv] * period); + if(ABS(freq - f) <= best_freq_err) + { + *out_period = period; + *out_cdiv = cdiv; + best_freq_err = ABS(freq - f); + } + } + } +} + +void imx233_pwm_setup_simple(int channel, int freq, int duty_cycle) +{ + int period, cdiv; + imx233_pwm_lookup_freq(freq, 100, &period, &cdiv); + int inactive = (period * duty_cycle) / 100; + imx233_pwm_setup(channel, period, cdiv, 0, BV_PWM_PERIODn_ACTIVE_STATE__1, + inactive, BV_PWM_PERIODn_INACTIVE_STATE__0); +} + +struct imx233_pwm_info_t imx233_pwm_get_info(int channel) +{ +#define ENTRY(mode, name, val) [BV_PWM_PERIODn_##mode##_STATE__##name] = val + static char active_state[] = + { + ENTRY(ACTIVE, 0, '0'), ENTRY(ACTIVE, 1, '1'), ENTRY(ACTIVE, HI_Z, 'Z') + }; + static char inactive_state[] = + { + ENTRY(INACTIVE, 0, '0'), ENTRY(INACTIVE, 1, '1'), ENTRY(INACTIVE, HI_Z, 'Z') + }; +#undef ENTRY + struct imx233_pwm_info_t info; + memset(&info, 0, sizeof(info)); + info.enabled = imx233_pwm_is_enabled(channel); + info.cdiv = pwm_cdiv_table[BF_RDn(PWM_PERIODn, channel, CDIV)]; + info.period = BF_RDn(PWM_PERIODn, channel, PERIOD) + 1; + info.active = BF_RDn(PWM_ACTIVEn, channel, ACTIVE); + info.inactive = BF_RDn(PWM_ACTIVEn, channel, INACTIVE); + info.active_state = active_state[BF_RDn(PWM_PERIODn, channel, ACTIVE_STATE)]; + info.inactive_state = inactive_state[BF_RDn(PWM_PERIODn, channel, INACTIVE_STATE)]; + return info; } diff --git a/firmware/target/arm/imx233/pwm-imx233.h b/firmware/target/arm/imx233/pwm-imx233.h index c7ec4c27c5..55c454b7cd 100644 --- a/firmware/target/arm/imx233/pwm-imx233.h +++ b/firmware/target/arm/imx233/pwm-imx233.h @@ -33,13 +33,26 @@ #define IMX233_PWM_NR_CHANNELS 5 -#define IMX233_PWM_PIN_BANK(channel) 1 -#define IMX233_PWM_PIN(channel) (26 + (channel)) - void imx233_pwm_init(void); -void imx233_pwm_setup_channel(int channel, int period, int cdiv, int active, +void imx233_pwm_setup(int channel, int period, int cdiv, int active, int active_state, int inactive, int inactive_state); -void imx233_pwm_enable_channel(int channel, bool enable); -bool imx233_pwm_is_channel_enable(int channel); +/* helper function to compute adequate divisor and period, given a minimum + * period resolution (for active/inactive) */ +void imx233_pwm_lookup_freq(int freq, int min_period, int *period, int *cdiv); +/* simple setup with active 1, inactive 0, duty cycle in percent */ +void imx233_pwm_setup_simple(int channel, int freq, int duty_cycle); +void imx233_pwm_enable(int channel, bool enable); +bool imx233_pwm_is_enabled(int channel); + +struct imx233_pwm_info_t +{ + bool enabled; + int cdiv; + int period; + int inactive, active; + char inactive_state, active_state; // '0', '1' or 'Z' +}; + +struct imx233_pwm_info_t imx233_pwm_get_info(int channel); #endif /* __PWM_IMX233_H__ */ |