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Date: Mon, 12 Dec 2022 11:17:44 +0200
From: Roger Quadros <rogerq@...nel.org>
To: Md Danish Anwar <a0501179@...com>,
MD Danish Anwar <danishanwar@...com>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Rob Herring <robh+dt@...nel.org>
Cc: Suman Anna <s-anna@...com>, "Andrew F . Davis" <afd@...com>,
nm@...com, vigneshr@...com, srk@...com,
linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [EXTERNAL] Re: [PATCH v11 3/6] remoteproc: pru: Add APIs to get
and put the PRU cores
Danish,
On 09/12/2022 06:55, Md Danish Anwar wrote:
> Hi Roger,
>
> On 08/12/22 16:05, Roger Quadros wrote:
>> Hi,
>>
>> On 07/12/2022 13:04, MD Danish Anwar wrote:
>>> Add two new APIs, pru_rproc_get() and pru_rproc_put(), to the PRU
>>> driver to allow client drivers to acquire and release the remoteproc
>>> device associated with a PRU core. The PRU cores are treated as
>>> resources with only one client owning it at a time.
>>>
>>> The pru_rproc_get() function returns the rproc handle corresponding
>>> to a PRU core identified by the device tree "ti,prus" property under
>>> the client node. The pru_rproc_put() is the complementary function
>>> to pru_rproc_get().
>>>
>>> Signed-off-by: Suman Anna <s-anna@...com>
>>> Signed-off-by: Tero Kristo <t-kristo@...com>
>>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
>>> Signed-off-by: MD Danish Anwar <danishanwar@...com>
>>> ---
>>> drivers/remoteproc/pru_rproc.c | 133 ++++++++++++++++++++++++++++++++-
>>> include/linux/pruss.h | 29 +++++++
>>> 2 files changed, 160 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
>>> index a1a208b31846..7d4ed39b3772 100644
>>> --- a/drivers/remoteproc/pru_rproc.c
>>> +++ b/drivers/remoteproc/pru_rproc.c
>>> @@ -2,12 +2,14 @@
>>> /*
>>> * PRU-ICSS remoteproc driver for various TI SoCs
>>> *
>>> - * Copyright (C) 2014-2020 Texas Instruments Incorporated - https://www.ti.com/
>>> + * Copyright (C) 2014-2022 Texas Instruments Incorporated - https://www.ti.com/
>>> *
>>> * Author(s):
>>> * Suman Anna <s-anna@...com>
>>> * Andrew F. Davis <afd@...com>
>>> * Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org> for Texas Instruments
>>> + * Puranjay Mohan <p-mohan@...com>
>>> + * Md Danish Anwar <danishanwar@...com>
>>> */
>>>
>>> #include <linux/bitops.h>
>>> @@ -112,6 +114,8 @@ struct pru_private_data {
>>> * @rproc: remoteproc pointer for this PRU core
>>> * @data: PRU core specific data
>>> * @mem_regions: data for each of the PRU memory regions
>>> + * @client_np: client device node
>>> + * @lock: mutex to protect client usage
>>> * @fw_name: name of firmware image used during loading
>>> * @mapped_irq: virtual interrupt numbers of created fw specific mapping
>>> * @pru_interrupt_map: pointer to interrupt mapping description (firmware)
>>> @@ -127,6 +131,8 @@ struct pru_rproc {
>>> struct rproc *rproc;
>>> const struct pru_private_data *data;
>>> struct pruss_mem_region mem_regions[PRU_IOMEM_MAX];
>>> + struct device_node *client_np;
>>> + struct mutex lock;
>>> const char *fw_name;
>>> unsigned int *mapped_irq;
>>> struct pru_irq_rsc *pru_interrupt_map;
>>> @@ -147,6 +153,125 @@ void pru_control_write_reg(struct pru_rproc *pru, unsigned int reg, u32 val)
>>> writel_relaxed(val, pru->mem_regions[PRU_IOMEM_CTRL].va + reg);
>>> }
>>>
>>> +static struct rproc *__pru_rproc_get(struct device_node *np, int index)
>>> +{
>>> + struct rproc *rproc;
>>> + phandle rproc_phandle;
>>> + int ret;
>>> +
>>> + ret = of_property_read_u32_index(np, "ti,prus", index, &rproc_phandle);
>>> + if (ret)
>>> + return ERR_PTR(ret);
>>> +
>>> + rproc = rproc_get_by_phandle(rproc_phandle);
>>> + if (!rproc) {
>>> + ret = -EPROBE_DEFER;
>>> + goto err_no_rproc_handle;
>>> + }
>>> +
>>> + /* make sure it is PRU rproc */
>>> + if (!is_pru_rproc(rproc->dev.parent)) {
>>> + rproc_put(rproc);
>>> + return ERR_PTR(-ENODEV);
>>> + }
>>> +
>>> + return rproc;
>>> +
>>> +err_no_rproc_handle:
>>> + rproc_put(rproc);
>>> + return ERR_PTR(ret);
>>> +}
>>> +
>>> +/**
>>> + * pru_rproc_get() - get the PRU rproc instance from a device node
>>> + * @np: the user/client device node
>>> + * @index: index to use for the ti,prus property
>>> + * @pru_id: optional pointer to return the PRU remoteproc processor id
>>> + *
>>> + * This function looks through a client device node's "ti,prus" property at
>>> + * index @index and returns the rproc handle for a valid PRU remote processor if
>>> + * found. The function allows only one user to own the PRU rproc resource at a
>>> + * time. Caller must call pru_rproc_put() when done with using the rproc, not
>>> + * required if the function returns a failure.
>>> + *
>>> + * When optional @pru_id pointer is passed the PRU remoteproc processor id is
>>> + * returned.
>>> + *
>>> + * Return: rproc handle on success, and an ERR_PTR on failure using one
>>> + * of the following error values
>>> + * -ENODEV if device is not found
>>> + * -EBUSY if PRU is already acquired by anyone
>>> + * -EPROBE_DEFER is PRU device is not probed yet
>>> + */
>>> +struct rproc *pru_rproc_get(struct device_node *np, int index,
>>> + enum pruss_pru_id *pru_id)
>>> +{
>>> + struct rproc *rproc;
>>> + struct pru_rproc *pru;
>>> + struct device *dev;
>>> + int ret;
>>> +
>>> + rproc = __pru_rproc_get(np, index);
>>> + if (IS_ERR(rproc))
>>> + return rproc;
>>> +
>>> + pru = rproc->priv;
>>> + dev = &rproc->dev;
>>> +
>>> + mutex_lock(&pru->lock);
>>> +
>>> + if (pru->client_np) {
>>> + mutex_unlock(&pru->lock);
>>> + put_device(dev);
>>
>> Is this put_device() to counter balance the get_device() you had earlier?
>> Is it still needed?
>>> Did we do the right thing by getting rid of the additional get_device()?
>> I didn't see a reason for it.
>>
>
> The previous get_device() in __pru_rproc_get() was additional/not required as
> the same get_device() was called by rproc_get_by_phandle() API before it's
> completion.
>
> So that get_device() is not needed.
>
> The put_device() here is to counter the get_device() called by
> rproc_get_by_phandle() in the API __pru_rproc_get().
>
> So I think, this put_device() is still needed.
But at the end of this function we are calling rproc_put()
which also does a put_device(), right?
>
>>> + ret = -EBUSY;
>>> + goto err_no_rproc_handle;
>>> + }
>>> +
>>> + pru->client_np = np;
>>> +
>>> + mutex_unlock(&pru->lock);
>>> +
>>> + if (pru_id)
>>> + *pru_id = pru->id;
>>> +
>>> + return rproc;
>>> +
>>> +err_no_rproc_handle:
>>> + rproc_put(rproc);
>>> + return ERR_PTR(ret);
>>> +}
>>> +EXPORT_SYMBOL_GPL(pru_rproc_get);
<snip>
cheers,
-roger
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