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Subject: Re: [PATCHv3 11/15] remoteproc/omap: Request a timer(s) for
 remoteproc usage
To:     Mathieu Poirier <mathieu.poirier@linaro.org>
CC:     <bjorn.andersson@linaro.org>, <ohad@wizery.com>,
        <linux-remoteproc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-omap@vger.kernel.org>, Suman Anna <s-anna@ti.com>
References: <20191213125537.11509-1-t-kristo@ti.com>
 <20191213125537.11509-12-t-kristo@ti.com> <20191218224355.GE16271@xps15>
From:   Tero Kristo <t-kristo@ti.com>
Message-ID: <0c994201-b6d8-9005-de87-9fa052cd9403@ti.com>
Date:   Thu, 19 Dec 2019 15:43:12 +0200
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On 19/12/2019 00:43, Mathieu Poirier wrote:
> On Fri, Dec 13, 2019 at 02:55:33PM +0200, Tero Kristo wrote:
>> From: Suman Anna <s-anna@ti.com>
>>
>> The remote processors in OMAP4+ SoCs are equipped with internal
>> timers, like the internal SysTick timer in a Cortex M3/M4 NVIC or
>> the CTM timer within Unicache in IPU & DSP. However, these timers
>> are gated when the processor subsystem clock is gated, making
>> them rather difficult to use as OS tick sources. They will not
>> be able to wakeup the processor from any processor-sleep induced
>> clock-gating states.
>>
>> This can be avoided by using an external timer as the tick source,
>> which can be controlled independently by the OMAP remoteproc
>> driver code, but still allowing the processor subsystem clock to
>> be auto-gated when the remoteproc cores are idle.
>>
>> This patch adds the support for OMAP remote processors to request
>> timer(s) to be used by the remoteproc. The timers are enabled and
>> disabled in line with the enabling/disabling of the remoteproc.
>> The timer data is not mandatory if the advanced device management
>> features are not required.
>>
>> The core timer functionality is provided by the OMAP DMTimer
>> clocksource driver, which does not export any API. The logic is
>> implemented through the timer device's platform data ops. The OMAP
>> remoteproc driver mainly requires ops to request/free a dmtimer,
>> and to start/stop a timer. The split ops helps in controlling the
>> timer state without having to request and release a timer everytime
>> it needs to use the timer.
>>
>> NOTE: If the gptimer is already in use by the time IPU and/or
>> DSP are loaded, the processors will fail to boot.
>>
>> Signed-off-by: Suman Anna <s-anna@ti.com>
>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>> ---
>>   drivers/remoteproc/omap_remoteproc.c | 258 +++++++++++++++++++++++++++
>>   1 file changed, 258 insertions(+)
>>
>> diff --git a/drivers/remoteproc/omap_remoteproc.c b/drivers/remoteproc/omap_remoteproc.c
>> index 841981c50d8d..9c750c2ab29d 100644
>> --- a/drivers/remoteproc/omap_remoteproc.c
>> +++ b/drivers/remoteproc/omap_remoteproc.c
>> @@ -26,6 +26,9 @@
>>   #include <linux/regmap.h>
>>   #include <linux/mfd/syscon.h>
>>   #include <linux/reset.h>
>> +#include <clocksource/timer-ti-dm.h>
>> +
>> +#include <linux/platform_data/dmtimer-omap.h>
>>   
>>   #include "omap_remoteproc.h"
>>   #include "remoteproc_internal.h"
>> @@ -57,6 +60,16 @@ struct omap_rproc_mem {
>>   	size_t size;
>>   };
>>   
>> +/**
>> + * 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
>> + */
>> +struct omap_rproc_timer {
>> +	struct omap_dm_timer *odt;
>> +	const struct omap_dm_timer_ops *timer_ops;
>> +};
>> +
>>   /**
>>    * struct omap_rproc - omap remote processor state
>>    * @mbox: mailbox channel handle
>> @@ -64,6 +77,8 @@ struct omap_rproc_mem {
>>    * @boot_data: boot data structure for setting processor boot address
>>    * @mem: internal memory regions data
>>    * @num_mems: number of internal memory regions
>> + * @num_timers: number of rproc timer(s)
>> + * @timers: timer(s) info used by rproc
>>    * @rproc: rproc handle
>>    * @reset: reset handle
>>    */
>> @@ -73,6 +88,8 @@ struct omap_rproc {
>>   	struct omap_rproc_boot_data *boot_data;
>>   	struct omap_rproc_mem *mem;
>>   	int num_mems;
>> +	int num_timers;
>> +	struct omap_rproc_timer *timers;
>>   	struct rproc *rproc;
>>   	struct reset_control *reset;
>>   };
>> @@ -93,6 +110,213 @@ struct omap_rproc_dev_data {
>>   	const u32 *dev_addrs;
>>   };
>>   
>> +/**
>> + * omap_rproc_request_timer() - request a timer for a remoteproc
>> + * @dev: device requesting the timer
>> + * @np: device node pointer to the desired timer
>> + * @timer: handle to a struct omap_rproc_timer to return the timer handle
>> + *
>> + * This helper function is used primarily to request a timer associated with
>> + * a remoteproc. The returned handle is stored in the .odt field of the
>> + * @timer structure passed in, and is used to invoke other timer specific
>> + * ops (like starting a timer either during device initialization or during
>> + * a resume operation, or for stopping/freeing a timer).
>> + *
>> + * Returns 0 on success, otherwise an appropriate failure
>> + */
>> +static int omap_rproc_request_timer(struct device *dev, struct device_node *np,
>> +				    struct omap_rproc_timer *timer)
>> +{
>> +	int ret;
>> +
>> +	timer->odt = timer->timer_ops->request_by_node(np);
>> +	if (!timer->odt) {
>> +		dev_err(dev, "request for timer node %p failed\n", np);
>> +		return -EBUSY;
>> +	}
>> +
>> +	ret = timer->timer_ops->set_source(timer->odt, OMAP_TIMER_SRC_SYS_CLK);
>> +	if (ret) {
>> +		dev_err(dev, "error setting OMAP_TIMER_SRC_SYS_CLK as source for timer node %p\n",
>> +			np);
>> +		timer->timer_ops->free(timer->odt);
>> +		return ret;
>> +	}
>> +
>> +	/* clean counter, remoteproc code will set the value */
>> +	timer->timer_ops->set_load(timer->odt, 0, 0);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * omap_rproc_start_timer - start a timer for a remoteproc
>> + * @timer: handle to a OMAP rproc timer
>> + *
>> + * This helper function is used to start a timer associated with a remoteproc,
>> + * obtained using the request_timer ops. The helper function needs to be
>> + * invoked by the driver to start the timer (during device initialization)
>> + * or to just resume the timer.
>> + *
>> + * Returns 0 on success, otherwise a failure as returned by DMTimer ops
>> + */
>> +static inline int omap_rproc_start_timer(struct omap_rproc_timer *timer)
>> +{
>> +	return timer->timer_ops->start(timer->odt);
>> +}
>> +
>> +/**
>> + * omap_rproc_stop_timer - stop a timer for a remoteproc
>> + * @timer: handle to a OMAP rproc timer
>> + *
>> + * This helper function is used to disable a timer associated with a
>> + * remoteproc, and needs to be called either during a device shutdown
>> + * or suspend operation. The separate helper function allows the driver
>> + * to just stop a timer without having to release the timer during a
>> + * suspend operation.
>> + *
>> + * Returns 0 on success, otherwise a failure as returned by DMTimer ops
>> + */
>> +static inline int omap_rproc_stop_timer(struct omap_rproc_timer *timer)
>> +{
>> +	return timer->timer_ops->stop(timer->odt);
>> +}
>> +
>> +/**
>> + * omap_rproc_release_timer - release a timer for a remoteproc
>> + * @timer: handle to a OMAP rproc timer
>> + *
>> + * This helper function is used primarily to release a timer associated
>> + * with a remoteproc. The dmtimer will be available for other clients to
>> + * use once released.
>> + *
>> + * Returns 0 on success, otherwise a failure as returned by DMTimer ops
>> + */
>> +static inline int omap_rproc_release_timer(struct omap_rproc_timer *timer)
>> +{
>> +	return timer->timer_ops->free(timer->odt);
>> +}
>> +
>> +/**
>> + * omap_rproc_enable_timers - enable the timers for a remoteproc
>> + * @rproc: handle of a remote processor
>> + * @configure: boolean flag used to acquire and configure the timer handle
>> + *
>> + * This function is used primarily to enable the timers associated with
>> + * a remoteproc. The configure flag is provided to allow the driver to
>> + * to either acquire and start a timer (during device initialization) or
>> + * to just start a timer (during a resume operation).
>> + */
>> +static int omap_rproc_enable_timers(struct rproc *rproc, bool configure)
>> +{
>> +	int i;
>> +	int ret = 0;
>> +	struct platform_device *tpdev;
>> +	struct dmtimer_platform_data *tpdata;
>> +	const struct omap_dm_timer_ops *timer_ops;
>> +	struct omap_rproc *oproc = rproc->priv;
>> +	struct omap_rproc_timer *timers = oproc->timers;
>> +	struct device *dev = rproc->dev.parent;
>> +	struct device_node *np = NULL;
>> +
>> +	if (oproc->num_timers <= 0)
>> +		return 0;
> 
> Given the code in omap_rproc_probe() ->num_timers can only be >= 0.

Will fix to check against 0 only.

> 
>> +
>> +	if (!configure)
>> +		goto start_timers;
>> +
>> +	for (i = 0; i < oproc->num_timers; i++) {
>> +		np = of_parse_phandle(dev->of_node, "ti,timers", i);
>> +		if (!np) {
>> +			ret = -ENXIO;
>> +			dev_err(dev, "device node lookup for timer at index %d failed: %d\n",
>> +				i, ret);
>> +			goto free_timers;
>> +		}
>> +
>> +		tpdev = of_find_device_by_node(np);
>> +		if (!tpdev) {
>> +			ret = -ENODEV;
>> +			dev_err(dev, "could not get timer platform device\n");
>> +			goto put_node;
>> +		}
>> +
>> +		tpdata = dev_get_platdata(&tpdev->dev);
>> +		put_device(&tpdev->dev);
>> +		if (!tpdata) {
>> +			ret = -EINVAL;
>> +			dev_err(dev, "dmtimer pdata structure NULL\n");
>> +			goto put_node;
>> +		}
>> +
>> +		timer_ops = tpdata->timer_ops;
>> +		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) {
>> +			ret = -EINVAL;
>> +			dev_err(dev, "device does not have required timer ops\n");
>> +			goto put_node;
>> +		}
>> +
>> +		timers[i].timer_ops = timer_ops;
>> +		ret = omap_rproc_request_timer(dev, np, &timers[i]);
>> +		if (ret) {
>> +			dev_err(dev, "request for timer %p failed: %d\n", np,
>> +				ret);
>> +			goto put_node;
>> +		}
>> +		of_node_put(np);
>> +	}
>> +
>> +start_timers:
>> +	for (i = 0; i < oproc->num_timers; i++)
>> +		omap_rproc_start_timer(&timers[i]);
> 
> The return code for omap_rproc_start_timer() is ignored.  If this is intentional
> then adding a comment to justify the choice is probably a good idea.  Otherwise
> please consider refactoring.

Will add a cleanup loop to clear this in failure.

> 
>> +	return 0;
>> +
>> +put_node:
>> +	of_node_put(np);
>> +free_timers:
>> +	while (i--) {
>> +		omap_rproc_release_timer(&timers[i]);
>> +		timers[i].odt = NULL;
>> +		timers[i].timer_ops = NULL;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * omap_rproc_disable_timers - disable the timers for a remoteproc
>> + * @rproc: handle of a remote processor
>> + * @configure: boolean flag used to release the timer handle
>> + *
>> + * This function is used primarily to disable the timers associated with
>> + * a remoteproc. The configure flag is provided to allow the driver to
>> + * to either stop and release a timer (during device shutdown) or to just
>> + * stop a timer (during a suspend operation).
>> + */
>> +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;
>> +
>> +	if (oproc->num_timers <= 0)
> 
> Same comment as above.

Will fix to check against 0 only.

> 
>> +		return 0;
>> +
>> +	for (i = 0; i < oproc->num_timers; i++) {
>> +		omap_rproc_stop_timer(&timers[i]);
>> +		if (configure) {
>> +			omap_rproc_release_timer(&timers[i]);
>> +			timers[i].odt = NULL;
>> +			timers[i].timer_ops = NULL;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   /**
>>    * omap_rproc_mbox_callback() - inbound mailbox message handler
>>    * @client: mailbox client pointer used for requesting the mailbox channel
>> @@ -228,6 +452,12 @@ static int omap_rproc_start(struct rproc *rproc)
>>   		goto put_mbox;
>>   	}
>>   
>> +	ret = omap_rproc_enable_timers(rproc, true);
>> +	if (ret) {
>> +		dev_err(dev, "omap_rproc_enable_timers failed: %d\n", ret);
>> +		goto put_mbox;
>> +	}
>> +
>>   	reset_control_deassert(oproc->reset);
>>   
>>   	return 0;
>> @@ -241,9 +471,14 @@ static int omap_rproc_start(struct rproc *rproc)
>>   static int omap_rproc_stop(struct rproc *rproc)
>>   {
>>   	struct omap_rproc *oproc = rproc->priv;
>> +	int ret;
>>   
>>   	reset_control_assert(oproc->reset);
>>   
>> +	ret = omap_rproc_disable_timers(rproc, true);
>> +	if (ret)
>> +		return ret;
>> +
>>   	mbox_free_channel(oproc->mbox);
>>   
>>   	return 0;
>> @@ -528,6 +763,29 @@ static int omap_rproc_probe(struct platform_device *pdev)
>>   	if (ret)
>>   		goto free_rproc;
>>   
>> +	/*
>> +	 * Timer nodes are directly used in client nodes as phandles, so
>> +	 * retrieve the count using appropriate size
>> +	 */
>> +	oproc->num_timers = of_count_phandle_with_args(np, "ti,timers", NULL);
>> +	if (oproc->num_timers <= 0) {
>> +		dev_dbg(&pdev->dev, "device does not have timers, status = %d\n",
>> +			oproc->num_timers);
>> +		oproc->num_timers = 0;
>> +	}
>> +
>> +	if (oproc->num_timers) {
>> +		oproc->timers = devm_kzalloc(&pdev->dev, sizeof(*oproc->timers)
>> +					     * oproc->num_timers, GFP_KERNEL);
> 
> Please use devm_kcalloc().

Will fix that.

-Tero

> 
> More comments to come tomorrow,
> Mathieu
> 
>> +		if (!oproc->timers) {
>> +			ret = -ENOMEM;
>> +			goto free_rproc;
>> +		}
>> +
>> +		dev_dbg(&pdev->dev, "device has %d tick timers\n",
>> +			oproc->num_timers);
>> +	}
>> +
>>   	ret = of_reserved_mem_device_init(&pdev->dev);
>>   	if (ret) {
>>   		dev_err(&pdev->dev, "device does not have specific CMA pool\n");
>> -- 
>> 2.17.1
>>
>> --

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