Re: [PATCH v2] clocksource: timer-ti-dm : Capture functionality for OMAP DM timer

[Gokul Praveen <g-praveen@ti.com>]

Hi Daniel,

Is this patch good to be merged?

Regards
Gokul

On 21/08/25 19:13, Neha Malcom Francis wrote:
> Hi Gokul
> 
> On 12/08/25 16:23, Gokul Praveen wrote:
>> Add PWM capture function in DM timer driver.
>>
>> OMAP DM timer hardware supports capture feature.It can be used to
>> timestamp events (falling/rising edges) detected on input signal.
>>
>> Signed-off-by: Gokul Praveen <g-praveen@ti.com>
>> ---
>> v2<==> v1
>> ===========
>> * Optimized the code and fixed some comment spacing and newline issues
>>
>> Precondition : Before calling driver API,it is assumed that the
>>                 capture signal is active else both duty cycle
>>                 and period returned by driver will not be valid.
>> ---
>>   drivers/clocksource/timer-ti-dm.c          | 119 ++++++++++++++++++++-
>>   include/linux/platform_data/dmtimer-omap.h |   4 +
>>   2 files changed, 121 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
>> index e9e32df6b566..793e7cdcb1b1 100644
>> --- a/drivers/clocksource/timer-ti-dm.c
>> +++ b/drivers/clocksource/timer-ti-dm.c
>> @@ -31,6 +31,7 @@
>>   #include <linux/platform_data/dmtimer-omap.h>
>>   
>>   #include <clocksource/timer-ti-dm.h>
>> +#include <linux/delay.h>
>>   
>>   /*
>>    * timer errata flags
>> @@ -836,6 +837,48 @@ static int omap_dm_timer_set_match(struct omap_dm_timer *cookie, int enable,
>>   	return 0;
>>   }
>>   
>> +static int omap_dm_timer_set_cap(struct omap_dm_timer *cookie,
>> +					int autoreload, bool config_period)
>> +{
>> +	struct dmtimer *timer;
>> +	struct device *dev;
>> +	int rc;
>> +	u32 l;
>> +
>> +	timer = to_dmtimer(cookie);
>> +	if (unlikely(!timer))
>> +		return -EINVAL;
>> +
>> +	dev = &timer->pdev->dev;
>> +	rc = pm_runtime_resume_and_get(dev);
>> +	if (rc)
>> +		return rc;
>> +	/*
>> +	 *  1. Select autoreload mode. TIMER_TCLR[1] AR bit.
>> +	 *  2. TIMER_TCLR[14]: Sets the functionality of the TIMER IO pin.
>> +	 *  3. TIMER_TCLR[13] : Capture mode select bit.
>> +	 *  3. TIMER_TCLR[9-8] : Select transition capture mode.
>> +	 */
>> +
>> +	l = dmtimer_read(timer, OMAP_TIMER_CTRL_REG);
>> +
>> +	if (autoreload)
>> +		l |= OMAP_TIMER_CTRL_AR;
>> +
>> +	l |= OMAP_TIMER_CTRL_CAPTMODE | OMAP_TIMER_CTRL_GPOCFG;
>> +
>> +	if (config_period == true)
>> +		l |= OMAP_TIMER_CTRL_TCM_LOWTOHIGH; /* Time Period config */
>> +	else
>> +		l |= OMAP_TIMER_CTRL_TCM_BOTHEDGES; /* Duty Cycle config */
>> +
>> +	dmtimer_write(timer, OMAP_TIMER_CTRL_REG, l);
>> +
>> +	pm_runtime_put_sync(dev);
>> +
>> +	return 0;
>> +}
>> +
>>   static int omap_dm_timer_set_pwm(struct omap_dm_timer *cookie, int def_on,
>>   				 int toggle, int trigger, int autoreload)
>>   {
>> @@ -1023,23 +1066,92 @@ static unsigned int omap_dm_timer_read_counter(struct omap_dm_timer *cookie)
>>   	return __omap_dm_timer_read_counter(timer);
>>   }
>>   
>> +static inline unsigned int __omap_dm_timer_cap(struct dmtimer *timer, int idx)
>> +{
>> +	return idx == 0 ? dmtimer_read(timer, OMAP_TIMER_CAPTURE_REG) :
>> +			  dmtimer_read(timer, OMAP_TIMER_CAPTURE2_REG);
>> +}
>> +
>>   static int omap_dm_timer_write_counter(struct omap_dm_timer *cookie, unsigned int value)
>>   {
>>   	struct dmtimer *timer;
>> +	struct device *dev;
>>   
>>   	timer = to_dmtimer(cookie);
>> -	if (unlikely(!timer || !atomic_read(&timer->enabled))) {
>> -		pr_err("%s: timer not available or enabled.\n", __func__);
>> +	if (unlikely(!timer)) {
>> +		pr_err("%s: timer not available.\n", __func__);
>>   		return -EINVAL;
>>   	}
>>   
>> +	dev = &timer->pdev->dev;
>> +
>> +	pm_runtime_resume_and_get(dev);
>>   	dmtimer_write(timer, OMAP_TIMER_COUNTER_REG, value);
>> +	pm_runtime_put_sync(dev);
>>   
>>   	/* Save the context */
>>   	timer->context.tcrr = value;
>>   	return 0;
>>   }
>>   
>> +/**
>> + * omap_dm_timer_cap_counter() - Calculate the high count or period count depending on the
>> + * configuration.
>> + * @cookie:Pointer to OMAP DM timer
>> + * @is_period:Whether to configure timer in period or duty cycle mode
>> + *
>> + * Return high count or period count if timer is enabled else appropriate error.
>> + */
>> +static unsigned int omap_dm_timer_cap_counter(struct omap_dm_timer *cookie,	bool is_period)
>> +{
>> +	struct dmtimer *timer;
>> +	unsigned int cap1 = 0;
>> +	unsigned int cap2 = 0;
>> +	u32 l, ret;
>> +
>> +	timer = to_dmtimer(cookie);
>> +	if (unlikely(!timer || !atomic_read(&timer->enabled))) {
>> +		pr_err("%s:timer is not available or enabled.%p\n", __func__, (void *)timer);
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* Stop the timer */
>> +	omap_dm_timer_stop(cookie);
>> +
>> +	/* Clear the timer counter value to 0 */
>> +	ret = omap_dm_timer_write_counter(cookie, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Sets the timer capture configuration for period/duty cycle calculation */
>> +	ret = omap_dm_timer_set_cap(cookie, true, is_period);
>> +	if (ret) {
>> +		pr_err("%s: Failed to set timer capture configuration.\n", __func__);
>> +		return ret;
>> +	}
>> +	/* Start the timer */
>> +	omap_dm_timer_start(cookie);
>> +
>> +	/*
>> +	 * 1 sec delay is given so as to provide
>> +	 * enough time to capture low frequency signals.
>> +	 */
>> +	msleep(1000);
>> +
>> +	cap1 = __omap_dm_timer_cap(timer, 0);
>> +	cap2 = __omap_dm_timer_cap(timer, 1);
>> +
>> +	/*
>> +	 *  Clears the TCLR configuration.
>> +	 *  The start bit must be set to 1 as the timer is already in start mode.
>> +	 */
>> +	l = dmtimer_read(timer, OMAP_TIMER_CTRL_REG);
>> +	l &= ~(0xffff) | 0x1;
>> +	dmtimer_write(timer, OMAP_TIMER_CTRL_REG, l);
>> +
>> +	return (cap2-cap1);
>> +}
>> +
>>   static int __maybe_unused omap_dm_timer_runtime_suspend(struct device *dev)
>>   {
>>   	struct dmtimer *timer = dev_get_drvdata(dev);
>> @@ -1246,6 +1358,9 @@ static const struct omap_dm_timer_ops dmtimer_ops = {
>>   	.write_counter = omap_dm_timer_write_counter,
>>   	.read_status = omap_dm_timer_read_status,
>>   	.write_status = omap_dm_timer_write_status,
>> +	.set_cap = omap_dm_timer_set_cap,
>> +	.get_cap_status = omap_dm_timer_get_pwm_status,
>> +	.read_cap = omap_dm_timer_cap_counter,
>>   };
>>   
>>   static const struct dmtimer_platform_data omap3plus_pdata = {
>> diff --git a/include/linux/platform_data/dmtimer-omap.h b/include/linux/platform_data/dmtimer-omap.h
>> index 95d852aef130..726d89143842 100644
>> --- a/include/linux/platform_data/dmtimer-omap.h
>> +++ b/include/linux/platform_data/dmtimer-omap.h
>> @@ -36,9 +36,13 @@ struct omap_dm_timer_ops {
>>   	int	(*set_pwm)(struct omap_dm_timer *timer, int def_on,
>>   			   int toggle, int trigger, int autoreload);
>>   	int	(*get_pwm_status)(struct omap_dm_timer *timer);
>> +	int	(*set_cap)(struct omap_dm_timer *timer,
>> +			   int autoreload, bool config_period);
>> +	int	(*get_cap_status)(struct omap_dm_timer *timer);
>>   	int	(*set_prescaler)(struct omap_dm_timer *timer, int prescaler);
>>   
>>   	unsigned int (*read_counter)(struct omap_dm_timer *timer);
>> +	unsigned int (*read_cap)(struct omap_dm_timer *timer, bool is_period);
>>   	int	(*write_counter)(struct omap_dm_timer *timer,
>>   				 unsigned int value);
>>   	unsigned int (*read_status)(struct omap_dm_timer *timer);
> 
> LGTM
> 
> Reviewed-by: Neha Malcom Francis <n-francis@ti.com>
>