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imx233: enhance pwm

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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 2013-06-16 20:15:32 +02:00
parent f5ac658d16
commit f8d2984875
4 changed files with 99 additions and 20 deletions
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82
firmware/target/arm/imx233/pwm-imx233.c
View file

@ -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;
}