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drivers: pwm_nrfx: Fix the driver to allow changing period on the fly

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Previously it was not possible to change the PWM period, even if only
a single channel was in use, without first stopping the peripheral,
i.e. setting pulse cycles for the channel to 0. This patch corrects
this behavior.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>
This commit is contained in:
Andrzej Głąbek 2019-11-04 13:12:28 +01:00 • committed by Carles Cufí
commit 51d055c520
1 changed files with 96 additions and 104 deletions
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200
drivers/pwm/pwm_nrfx.c
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@ -31,73 +31,56 @@ struct pwm_nrfx_data {
u8_t prescaler; u8_t prescaler;
}; };
static u32_t pwm_period_check_and_set(const struct pwm_nrfx_config *config,
struct pwm_nrfx_data *data,
u32_t pwm,
u32_t period_cycles)
{
NRF_PWM_Type *pwm_instance = config->pwm.p_registers;
if (!nrfx_pwm_is_stopped(&config->pwm)) { static int pwm_period_check_and_set(const struct pwm_nrfx_config *config,
/* Succeed if requested period matches already used period */ struct pwm_nrfx_data *data,
if (period_cycles == data->period_cycles) { u32_t channel,
u32_t period_cycles)
{
u8_t i;
u8_t prescaler;
u32_t countertop;
/* If any other channel (other than the one being configured) is set up
* with a non-zero pulse cycle, the period that is currently set cannot
* be changed, as this would influence the output for this channel.
*/
for (i = 0; i < NRF_PWM_CHANNEL_COUNT; ++i) {
if (i != channel) {
u16_t channel_pulse_cycle =
data->current[i]
& PWM_NRFX_CH_PULSE_CYCLES_MASK;
if (channel_pulse_cycle > 0) {
LOG_ERR("Incompatible period.");
return -EINVAL;
}
}
}
/* Try to find a prescaler that will allow setting the requested period
* after prescaling as the countertop value for the PWM peripheral.
*/
prescaler = 0;
countertop = period_cycles;
do {
if (countertop <= PWM_COUNTERTOP_COUNTERTOP_Msk) {
data->period_cycles = period_cycles;
data->prescaler = prescaler;
data->countertop = (u16_t)countertop;
nrf_pwm_configure(config->pwm.p_registers,
data->prescaler,
config->initial_config.count_mode,
data->countertop);
return 0; return 0;
} }
/* Fail if requested period != already running period */ countertop >>= 1;
LOG_ERR("Fail:requested period cycles:%d, != used %d\n", ++prescaler;
period_cycles, data->period_cycles); } while (prescaler <= PWM_PRESCALER_PRESCALER_Msk);
return -EINVAL;
}
/* Check if period_cycles is above COUNTERTOP MAX value, if so, we LOG_ERR("Prescaler for period_cycles %u not found.", period_cycles);
* have to see if we can change frequency to something that will fit return -EINVAL;
*/
if (period_cycles > PWM_COUNTERTOP_COUNTERTOP_Msk) {
/* See if there is a prescaler that will make it work: */
bool matching_prescaler_found = false;
/* Go through all available prescaler values on device (skip 0
* here as it is used in the 'else' block).
* nRF52832 has 0-7 (Div1 - Div128)
*/
for (u8_t prescaler = 1;
prescaler <= PWM_PRESCALER_PRESCALER_Msk;
prescaler++) {
u32_t new_countertop = period_cycles >> prescaler;
/* If we find value that fits, set it, continue */
if (new_countertop <= PWM_COUNTERTOP_COUNTERTOP_Msk) {
data->prescaler = prescaler;
data->countertop = new_countertop;
data->period_cycles = period_cycles;
matching_prescaler_found = true;
break;
}
}
/* Check if able to find matching prescaler and countertop */
if (matching_prescaler_found == false) {
LOG_ERR("Prescaler for period_cycles %d not found.\n",
period_cycles);
return -EINVAL;
}
} else {
/* If period_cycles fit the PWM counter without dividing
* the PWM clock, use the zero prescaler.
*/
data->prescaler = 0U;
data->countertop = period_cycles;
data->period_cycles = period_cycles;
}
/* Write new PRESCALER and COUNTERTOP to PWM instance */
nrf_pwm_configure(pwm_instance,
data->prescaler,
config->initial_config.count_mode,
data->countertop);
return 0;
} }
static u8_t pwm_channel_map(const uint8_t *output_pins, u32_t pwm) static u8_t pwm_channel_map(const uint8_t *output_pins, u32_t pwm)
@ -116,17 +99,22 @@ static u8_t pwm_channel_map(const uint8_t *output_pins, u32_t pwm)
return NRF_PWM_CHANNEL_COUNT; return NRF_PWM_CHANNEL_COUNT;
} }
static bool any_channel_active(const struct pwm_nrfx_data *data) static bool pwm_channel_is_active(u8_t channel,
const struct pwm_nrfx_data *data)
{ {
u8_t channel; u16_t pulse_cycle =
data->current[channel] & PWM_NRFX_CH_PULSE_CYCLES_MASK;
for (channel = 0U; channel < NRF_PWM_CHANNEL_COUNT; channel++) { return (pulse_cycle > 0 && pulse_cycle < data->countertop);
u16_t channel_pulse_cycle = }
data->current[channel]
& PWM_NRFX_CH_PULSE_CYCLES_MASK;
if (channel_pulse_cycle > 0 static bool any_other_channel_is_active(u8_t channel,
&& channel_pulse_cycle < data->countertop) { const struct pwm_nrfx_data *data)
{
u8_t i;
for (i = 0; i < NRF_PWM_CHANNEL_COUNT; ++i) {
if (i != channel && pwm_channel_is_active(i, data)) {
return true; return true;
} }
} }
@ -145,7 +133,6 @@ static int pwm_nrfx_pin_set(struct device *dev, u32_t pwm,
const struct pwm_nrfx_config *config = dev->config->config_info; const struct pwm_nrfx_config *config = dev->config->config_info;
struct pwm_nrfx_data *data = dev->driver_data; struct pwm_nrfx_data *data = dev->driver_data;
u8_t channel; u8_t channel;
u32_t ret;
/* Check if PWM pin is one of the predefiend DTS config pins. /* Check if PWM pin is one of the predefiend DTS config pins.
* Return its array index (channel number), * Return its array index (channel number),
@ -170,29 +157,35 @@ static int pwm_nrfx_pin_set(struct device *dev, u32_t pwm,
/* Check if period_cycle is either matching currently used, or /* Check if period_cycle is either matching currently used, or
* possible to use with our prescaler options. * possible to use with our prescaler options.
*/ */
ret = pwm_period_check_and_set(config, data, pwm, period_cycles); if (period_cycles != data->period_cycles) {
if (ret) { int ret = pwm_period_check_and_set(config, data, channel,
LOG_ERR("Incompatible period %d", period_cycles); period_cycles);
return ret; if (ret) {
return ret;
}
} }
/* Check if pulse is bigger than period, fail if so */ /* Limit pulse cycles to period cycles (meaning 100% duty), bigger
if (pulse_cycles > period_cycles) { * values might not fit after prescaling into the 15-bit field that
LOG_ERR("Invalid pulse_cycles %d, > period_cycles %d.", * is filled below.
pulse_cycles, period_cycles); */
return -EINVAL; pulse_cycles = MIN(pulse_cycles, period_cycles);
}
/* Store new pulse value bit[14:0], and polarity bit[15] for channel. */ /* Store new pulse value bit[14:0], and polarity bit[15] for channel. */
data->current[channel] = ( data->current[channel] = (
(data->current[channel] & PWM_NRFX_CH_POLARITY_MASK) (data->current[channel] & PWM_NRFX_CH_POLARITY_MASK)
| (pulse_cycles >> data->prescaler)); | (pulse_cycles >> data->prescaler));
/* If Channel is off/fully on (duty 0% or 100%), also set GPIO register LOG_DBG("pin %u, pulse %u, period %u, prescaler: %u.",
* since this will the setting if we in the future disable the pwm, pulse_cycles, period_cycles, data->prescaler);
* peripheral when no channels are active.
/* If this channel turns out to not need to be driven by the PWM
* peripheral (it is off or fully on - duty 0% or 100%), set properly
* the GPIO configuration for its output pin. This will provide
* the correct output state for this channel when the PWM peripheral
* is disabled after all channels appear to be inactive.
*/ */
if (pulse_cycles == 0U || pulse_cycles == period_cycles) { if (!pwm_channel_is_active(channel, data)) {
/* If pulse 0% and pin not inverted, set LOW. /* If pulse 0% and pin not inverted, set LOW.
* If pulse 100% and pin inverted, set LOW. * If pulse 100% and pin inverted, set LOW.
* If pulse 0% and pin inverted, set HIGH. * If pulse 0% and pin inverted, set HIGH.
@ -214,23 +207,22 @@ static int pwm_nrfx_pin_set(struct device *dev, u32_t pwm,
} else { } else {
nrf_gpio_pin_set(pwm); nrf_gpio_pin_set(pwm);
} }
}
/* Check if all channels are off (duty 0% or 100%) */ if (!any_other_channel_is_active(channel, data)) {
if (!any_channel_active(data)) { nrfx_pwm_stop(&config->pwm, false);
nrfx_pwm_stop(&config->pwm, false); }
} else { } else {
/* A PWM Channel is active: Start sequence. */
/* Since we are playing the sequence in a loop, the /* Since we are playing the sequence in a loop, the
* sequence only has to be started when its not already * sequence only has to be started when its not already
* playing. The new channel values will be used * playing. The new channel values will be used
* immediately when they are written into the seq array. * immediately when they are written into the seq array.
*/ */
nrfx_pwm_simple_playback(&config->pwm, if (nrfx_pwm_is_stopped(&config->pwm)) {
&config->seq, nrfx_pwm_simple_playback(&config->pwm,
1, &config->seq,
NRFX_PWM_FLAG_LOOP); 1,
NRFX_PWM_FLAG_LOOP);
}
} }
return 0; return 0;
@ -350,13 +342,15 @@ static int pwm_nrfx_pm_control(struct device *dev,
#endif /* CONFIG_DEVICE_POWER_MANAGEMENT */ #endif /* CONFIG_DEVICE_POWER_MANAGEMENT */
#define PWM_NRFX_IS_INVERTED(dev_idx, ch_idx) \
IS_ENABLED(DT_NORDIC_NRF_PWM_PWM_##dev_idx##_CH##ch_idx##_INVERTED)
#define PWM_NRFX_OUTPUT_PIN(dev_idx, ch_idx) \ #define PWM_NRFX_OUTPUT_PIN(dev_idx, ch_idx) \
(DT_NORDIC_NRF_PWM_PWM_##dev_idx##_CH##ch_idx##_PIN | \ (DT_NORDIC_NRF_PWM_PWM_##dev_idx##_CH##ch_idx##_PIN | \
(IS_ENABLED(DT_NORDIC_NRF_PWM_PWM_##dev_idx##_CH##ch_idx##_INVERTED) ?\ (PWM_NRFX_IS_INVERTED(dev_idx, ch_idx) ? NRFX_PWM_PIN_INVERTED : 0))
NRFX_PWM_PIN_INVERTED : 0))
#define PWM_NRFX_DEFAULT_VALUE(dev_idx, ch_idx) \ #define PWM_NRFX_DEFAULT_VALUE(dev_idx, ch_idx) \
(IS_ENABLED(DT_NORDIC_NRF_PWM_PWM_##dev_idx##_CH##ch_idx##_INVERTED) ? \ (PWM_NRFX_IS_INVERTED(dev_idx, ch_idx) ? \
PWM_NRFX_CH_VALUE_INVERTED : PWM_NRFX_CH_VALUE_NORMAL) PWM_NRFX_CH_VALUE_INVERTED : PWM_NRFX_CH_VALUE_NORMAL)
#define PWM_NRFX_COUNT_MODE(dev_idx) \ #define PWM_NRFX_COUNT_MODE(dev_idx) \
@ -370,11 +364,9 @@ static int pwm_nrfx_pm_control(struct device *dev,
PWM_NRFX_DEFAULT_VALUE(idx, 1), \ PWM_NRFX_DEFAULT_VALUE(idx, 1), \
PWM_NRFX_DEFAULT_VALUE(idx, 2), \ PWM_NRFX_DEFAULT_VALUE(idx, 2), \
PWM_NRFX_DEFAULT_VALUE(idx, 3), \ PWM_NRFX_DEFAULT_VALUE(idx, 3), \
}, \ } \
.countertop = NRFX_PWM_DEFAULT_CONFIG_TOP_VALUE, \
.prescaler = NRFX_PWM_DEFAULT_CONFIG_BASE_CLOCK \
}; \ }; \
static const struct pwm_nrfx_config pwm_nrfx_##idx##z_config = { \ static const struct pwm_nrfx_config pwm_nrfx_##idx##config = { \
.pwm = NRFX_PWM_INSTANCE(idx), \ .pwm = NRFX_PWM_INSTANCE(idx), \
.initial_config = { \ .initial_config = { \
.output_pins = { \ .output_pins = { \
@ -397,7 +389,7 @@ static int pwm_nrfx_pm_control(struct device *dev,
DT_NORDIC_NRF_PWM_PWM_##idx##_LABEL, \ DT_NORDIC_NRF_PWM_PWM_##idx##_LABEL, \
pwm_nrfx_init, pwm_##idx##_nrfx_pm_control, \ pwm_nrfx_init, pwm_##idx##_nrfx_pm_control, \
&pwm_nrfx_##idx##_data, \ &pwm_nrfx_##idx##_data, \
&pwm_nrfx_##idx##z_config, \ &pwm_nrfx_##idx##config, \
POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEVICE, \ POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEVICE, \
&pwm_nrfx_drv_api_funcs) &pwm_nrfx_drv_api_funcs)