Re: [PATCHv8 14/15] remoteproc/omap: Add watchdog functionality for remote processors

[Suman Anna <s-anna@ti.com>]

On 3/20/20 3:32 PM, Mathieu Poirier wrote:
> On Fri, Mar 13, 2020 at 10:17:17AM +0200, Tero Kristo wrote:
>> From: Suman Anna <s-anna@ti.com>
>>
>> Remote processors can be stuck in a loop, and may not be recoverable
>> if they do not have a built-in watchdog. The watchdog implementation
>> for OMAP remote processors uses external gptimers that can be used
>> to interrupt both the Linux host as well as the remote processor.
>>
>> Each remote processor is responsible for refreshing the timer during
>> normal behavior - during OS task scheduling or entering the idle loop
>> properly. During a watchdog condition (executing a tight loop causing
>> no scheduling), the host processor gets interrupts and schedules a
>> recovery for the corresponding remote processor. The remote processor
>> may also get interrupted to be able to print a back trace.
>>
>> A menuconfig option has also been added to enable/disable the Watchdog
>> functionality, with the default as disabled.
>>
>> Signed-off-by: Suman Anna <s-anna@ti.com>
>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>> Reviewed-by: Andrew F. Davis <afd@ti.com>
>> ---
>> v8:
>>   - minor cosmetic changes
>>
>>  drivers/remoteproc/Kconfig           |  12 +++
>>  drivers/remoteproc/omap_remoteproc.c | 152 +++++++++++++++++++++++++--
>>  2 files changed, 153 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
>> index b52abc2268cc..5f33358eb2f1 100644
>> --- a/drivers/remoteproc/Kconfig
>> +++ b/drivers/remoteproc/Kconfig
>> @@ -52,6 +52,18 @@ config OMAP_REMOTEPROC
>>  	  It's safe to say N here if you're not interested in multimedia
>>  	  offloading or just want a bare minimum kernel.
>>  
>> +config OMAP_REMOTEPROC_WATCHDOG
>> +	bool "OMAP remoteproc watchdog timer"
>> +	depends on OMAP_REMOTEPROC
>> +	default n
>> +	help
>> +	  Say Y here to enable watchdog timer for remote processors.
>> +
>> +	  This option controls the watchdog functionality for the remote
>> +	  processors in OMAP. Dedicated OMAP DMTimers are used by the remote
>> +	  processors and triggers the timer interrupt upon a watchdog
>> +	  detection.
>> +
>>  config WKUP_M3_RPROC
>>  	tristate "AMx3xx Wakeup M3 remoteproc support"
>>  	depends on SOC_AM33XX || SOC_AM43XX
>> diff --git a/drivers/remoteproc/omap_remoteproc.c b/drivers/remoteproc/omap_remoteproc.c
>> index ece60a183e19..29d19a608af8 100644
>> --- a/drivers/remoteproc/omap_remoteproc.c
>> +++ b/drivers/remoteproc/omap_remoteproc.c
>> @@ -24,6 +24,7 @@
>>  #include <linux/platform_device.h>
>>  #include <linux/pm_runtime.h>
>>  #include <linux/dma-mapping.h>
>> +#include <linux/interrupt.h>
>>  #include <linux/remoteproc.h>
>>  #include <linux/mailbox_client.h>
>>  #include <linux/omap-iommu.h>
>> @@ -72,10 +73,12 @@ struct omap_rproc_mem {
>>   * struct omap_rproc_timer - data structure for a timer used by a omap rproc
>>   * @odt: timer pointer
>>   * @timer_ops: OMAP dmtimer ops for @odt timer
>> + * @irq: timer irq
>>   */
>>  struct omap_rproc_timer {
>>  	struct omap_dm_timer *odt;
>>  	const struct omap_dm_timer_ops *timer_ops;
>> +	int irq;
>>  };
>>  
>>  /**
>> @@ -86,6 +89,7 @@ struct omap_rproc_timer {
>>   * @mem: internal memory regions data
>>   * @num_mems: number of internal memory regions
>>   * @num_timers: number of rproc timer(s)
>> + * @num_wd_timers: number of rproc watchdog timers
>>   * @timers: timer(s) info used by rproc
>>   * @autosuspend_delay: auto-suspend delay value to be used for runtime pm
>>   * @need_resume: if true a resume is needed in the system resume callback
>> @@ -102,6 +106,7 @@ struct omap_rproc {
>>  	struct omap_rproc_mem *mem;
>>  	int num_mems;
>>  	int num_timers;
>> +	int num_wd_timers;
>>  	struct omap_rproc_timer *timers;
>>  	int autosuspend_delay;
>>  	bool need_resume;
>> @@ -219,6 +224,79 @@ static inline int omap_rproc_release_timer(struct omap_rproc_timer *timer)
>>  	return timer->timer_ops->free(timer->odt);
>>  }
>>  
>> +/**
>> + * omap_rproc_get_timer_irq() - get the irq for a timer
>> + * @timer: handle to a OMAP rproc timer
>> + *
>> + * This function is used to get the irq associated with a watchdog timer. The
>> + * function is called by the OMAP remoteproc driver to register a interrupt
>> + * handler to handle watchdog events on the remote processor.
>> + *
>> + * Return: irq id on success, otherwise a failure as returned by DMTimer ops
>> + */
>> +static inline int omap_rproc_get_timer_irq(struct omap_rproc_timer *timer)
>> +{
>> +	return timer->timer_ops->get_irq(timer->odt);
>> +}
>> +
>> +/**
>> + * omap_rproc_ack_timer_irq() - acknowledge a timer irq
>> + * @timer: handle to a OMAP rproc timer
>> + *
>> + * This function is used to clear the irq associated with a watchdog timer. The
>> + * The function is called by the OMAP remoteproc upon a watchdog event on the
>> + * remote processor to clear the interrupt status of the watchdog timer.
>> + */
>> +static inline void omap_rproc_ack_timer_irq(struct omap_rproc_timer *timer)
>> +{
>> +	timer->timer_ops->write_status(timer->odt, OMAP_TIMER_INT_OVERFLOW);
>> +}
>> +
>> +/**
>> + * omap_rproc_watchdog_isr() - Watchdog ISR handler for remoteproc device
>> + * @irq: IRQ number associated with a watchdog timer
>> + * @data: IRQ handler data
>> + *
>> + * This ISR routine executes the required necessary low-level code to
>> + * acknowledge a watchdog timer interrupt. There can be multiple watchdog
>> + * timers associated with a rproc (like IPUs which have 2 watchdog timers,
>> + * one per Cortex M3/M4 core), so a lookup has to be performed to identify
>> + * the timer to acknowledge its interrupt.
>> + *
>> + * The function also invokes rproc_report_crash to report the watchdog event
>> + * to the remoteproc driver core, to trigger a recovery.
>> + *
>> + * Return: IRQ_HANDLED on success, otherwise IRQ_NONE
>> + */
>> +static irqreturn_t omap_rproc_watchdog_isr(int irq, void *data)
>> +{
>> +	struct rproc *rproc = data;
>> +	struct omap_rproc *oproc = rproc->priv;
>> +	struct device *dev = rproc->dev.parent;
>> +	struct omap_rproc_timer *timers = oproc->timers;
>> +	struct omap_rproc_timer *wd_timer = NULL;
>> +	int num_timers = oproc->num_timers + oproc->num_wd_timers;
>> +	int i;
>> +
>> +	for (i = oproc->num_timers; i < num_timers; i++) {
>> +		if (timers[i].irq > 0 && irq == timers[i].irq) {
>> +			wd_timer = &timers[i];
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (!wd_timer) {
>> +		dev_err(dev, "invalid timer\n");
>> +		return IRQ_NONE;
>> +	}
>> +
>> +	omap_rproc_ack_timer_irq(wd_timer);
>> +
>> +	rproc_report_crash(rproc, RPROC_WATCHDOG);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>>  /**
>>   * omap_rproc_enable_timers() - enable the timers for a remoteproc
>>   * @rproc: handle of a remote processor
>> @@ -242,19 +320,26 @@ static int omap_rproc_enable_timers(struct rproc *rproc, bool configure)
>>  	struct omap_rproc_timer *timers = oproc->timers;
>>  	struct device *dev = rproc->dev.parent;
>>  	struct device_node *np = NULL;
>> +	int num_timers = oproc->num_timers + oproc->num_wd_timers;
>>  
>> -	if (!oproc->num_timers)
>> +	if (!num_timers)
>>  		return 0;
>>  
>>  	if (!configure)
>>  		goto start_timers;
>>  
>> -	for (i = 0; i < oproc->num_timers; i++) {
>> -		np = of_parse_phandle(dev->of_node, "ti,timers", i);
>> +	for (i = 0; i < num_timers; i++) {
>> +		if (i < oproc->num_timers)
>> +			np = of_parse_phandle(dev->of_node, "ti,timers", i);
>> +		else
>> +			np = of_parse_phandle(dev->of_node,
>> +					      "ti,watchdog-timers",
>> +					      (i - oproc->num_timers));
>>  		if (!np) {
>>  			ret = -ENXIO;
>>  			dev_err(dev, "device node lookup for timer at index %d failed: %d\n",
>> -				i, ret);
>> +				i < oproc->num_timers ? i :
>> +				i - oproc->num_timers, ret);
>>  			goto free_timers;
>>  		}
>>  
>> @@ -277,12 +362,14 @@ static int omap_rproc_enable_timers(struct rproc *rproc, bool configure)
>>  		if (!timer_ops || !timer_ops->request_by_node ||
>>  		    !timer_ops->set_source || !timer_ops->set_load ||
>>  		    !timer_ops->free || !timer_ops->start ||
>> -		    !timer_ops->stop) {
>> +		    !timer_ops->stop || !timer_ops->get_irq ||
>> +		    !timer_ops->write_status) {
>>  			ret = -EINVAL;
>>  			dev_err(dev, "device does not have required timer ops\n");
>>  			goto put_node;
>>  		}
>>  
>> +		timers[i].irq = -1;
>>  		timers[i].timer_ops = timer_ops;
>>  		ret = omap_rproc_request_timer(dev, np, &timers[i]);
>>  		if (ret) {
>> @@ -291,10 +378,33 @@ static int omap_rproc_enable_timers(struct rproc *rproc, bool configure)
>>  			goto put_node;
>>  		}
>>  		of_node_put(np);
>> +
>> +		if (i >= oproc->num_timers) {
>> +			timers[i].irq = omap_rproc_get_timer_irq(&timers[i]);
>> +			if (timers[i].irq < 0) {
>> +				dev_err(dev, "get_irq for timer %p failed: %d\n",
>> +					np, timers[i].irq);
>> +				ret = -EBUSY;
>> +				goto free_timers;
>> +			}
>> +
>> +			ret = request_irq(timers[i].irq,
>> +					  omap_rproc_watchdog_isr, IRQF_SHARED,
>> +					  "rproc-wdt", rproc);
>> +			if (ret) {
>> +				dev_err(dev, "error requesting irq for timer %p\n",
>> +					np);
>> +				omap_rproc_release_timer(&timers[i]);
>> +				timers[i].odt = NULL;
>> +				timers[i].timer_ops = NULL;
>> +				timers[i].irq = -1;
>> +				goto free_timers;
>> +			}
>> +		}
>>  	}
>>  
>>  start_timers:
>> -	for (i = 0; i < oproc->num_timers; i++) {
>> +	for (i = 0; i < num_timers; i++) {
>>  		ret = omap_rproc_start_timer(&timers[i]);
>>  		if (ret) {
>>  			dev_err(dev, "start timer %p failed failed: %d\n", np,
>> @@ -316,9 +426,12 @@ static int omap_rproc_enable_timers(struct rproc *rproc, bool configure)
>>  		of_node_put(np);
>>  free_timers:
>>  	while (i--) {
>> +		if (i >= oproc->num_timers)
>> +			free_irq(timers[i].irq, rproc);
>>  		omap_rproc_release_timer(&timers[i]);
>>  		timers[i].odt = NULL;
>>  		timers[i].timer_ops = NULL;
>> +		timers[i].irq = -1;
>>  	}
>>  
>>  	return ret;
>> @@ -341,16 +454,20 @@ static int omap_rproc_disable_timers(struct rproc *rproc, bool configure)
>>  	int i;
>>  	struct omap_rproc *oproc = rproc->priv;
>>  	struct omap_rproc_timer *timers = oproc->timers;
>> +	int num_timers = oproc->num_timers + oproc->num_wd_timers;
>>  
>> -	if (!oproc->num_timers)
>> +	if (!num_timers)
>>  		return 0;
>>  
>> -	for (i = 0; i < oproc->num_timers; i++) {
>> +	for (i = 0; i < num_timers; i++) {
>>  		omap_rproc_stop_timer(&timers[i]);
>>  		if (configure) {
>> +			if (i >= oproc->num_timers)
>> +				free_irq(timers[i].irq, rproc);
>>  			omap_rproc_release_timer(&timers[i]);
>>  			timers[i].odt = NULL;
>>  			timers[i].timer_ops = NULL;
>> +			timers[i].irq = -1;
>>  		}
>>  	}
>>  
>> @@ -1110,6 +1227,7 @@ static int omap_rproc_of_get_timers(struct platform_device *pdev,
>>  	struct device_node *np = pdev->dev.of_node;
>>  	struct omap_rproc *oproc = rproc->priv;
>>  	struct device *dev = &pdev->dev;
>> +	int num_timers;
>>  
>>  	/*
>>  	 * Timer nodes are directly used in client nodes as phandles, so
>> @@ -1122,14 +1240,26 @@ static int omap_rproc_of_get_timers(struct platform_device *pdev,
>>  		oproc->num_timers = 0;
>>  	}
>>  
>> -	if (oproc->num_timers) {
>> -		oproc->timers = devm_kcalloc(dev, oproc->num_timers,
>> +#ifdef CONFIG_OMAP_REMOTEPROC_WATCHDOG
>> +	oproc->num_wd_timers =
>> +		of_count_phandle_with_args(np, "ti,watchdog-timers", NULL);
>> +	if (oproc->num_wd_timers <= 0) {
>> +		dev_dbg(dev, "device does not have watchdog timers, status = %d\n",
>> +			oproc->num_wd_timers);
>> +		oproc->num_wd_timers = 0;
>> +	}
>> +#endif
> 
> I commented on the above in the previous version...

Oh, misunderstood your agreed response. I have moved the entire timer
parse into a separate function. Do you still prefer just this block to
be defined in its own function, it is already self-contained?

regards
Suman

> 
>> +
>> +	num_timers = oproc->num_timers + oproc->num_wd_timers;
>> +	if (num_timers) {
>> +		oproc->timers = devm_kcalloc(dev, num_timers,
>>  					     sizeof(*oproc->timers),
>>  					     GFP_KERNEL);
>>  		if (!oproc->timers)
>>  			return -ENOMEM;
>>  
>> -		dev_dbg(dev, "device has %d tick timers\n", oproc->num_timers);
>> +		dev_dbg(dev, "device has %d tick timers and %d watchdog timers\n",
>> +			oproc->num_timers, oproc->num_wd_timers);
>>  	}
>>  
>>  	return 0;
>> -- 
>> 2.17.1
>>
>> --
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