Message-ID: <694da03a-e34d-1939-8b01-a75bc25495e0@ti.com>
Date:   Wed, 7 Sep 2022 14:54:14 +0530
From:   Md Danish Anwar <a0501179@...com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
CC:     Kishon Vijay Abraham I <kishon@...com>,
        Md Danish Anwar <danishanwar@...com>,
        <linux-kernel@...r.kernel.org>, <bjorn.andersson@...aro.org>,
        <krzysztof.kozlowski+dt@...aro.org>,
        <linux-remoteproc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <nm@...com>, <ssantosh@...nel.org>, <s-anna@...com>,
        <linux-arm-kernel@...ts.infradead.org>, <rogerq@...nel.org>,
        <grygorii.strashko@...com>, <vigneshr@...com>, <robh@...nel.org>
Subject: Re: [PATCH v5 2/6] remoteproc: pru: Add APIs to get and put the PRU
 cores

Hi Mathieu,

On 07/09/22 00:58, Mathieu Poirier wrote:
> On Fri, Sep 02, 2022 at 03:09:04PM +0530, Md Danish Anwar wrote:
>> Hi Mathieu,
>>
>>
>> On 15/07/22 11:52, Kishon Vijay Abraham I wrote:
>>> +Danish
>>>
>>> Hi Mathieu,
>>>
>>> On 14/07/22 22:50, Mathieu Poirier wrote:
>>>> On Tue, Jul 12, 2022 at 11:59:49AM -0600, Mathieu Poirier wrote:
>>>>> Hi Puranjay,
>>>
>>> Removed Puranjay (as he is no longer with TI) and adding Danish.
>>>
>>> Regards,
>>> Kishon
>>>>>
>>>>> On Tue, Jun 07, 2022 at 10:26:46AM +0530, Puranjay Mohan wrote:
>>>>>> From: Tero Kristo <t-kristo@...com>
>>>>>>
>>>>>> 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().
>>>>>>
>>>>>> Co-developed-by: Suman Anna <s-anna@...com>
>>>>>> Signed-off-by: Suman Anna <s-anna@...com>
>>>>>> Signed-off-by: Tero Kristo <t-kristo@...com>
>>>>>> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
>>>>>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
>>>>>> Co-developed-by: Puranjay Mohan <p-mohan@...com>
>>>>>> Signed-off-by: Puranjay Mohan <p-mohan@...com>
>>>>>> ---
>>>>>>   drivers/remoteproc/pru_rproc.c | 138 +++++++++++++++++++++++++++++++--
>>>>>>   include/linux/pruss.h          |  56 +++++++++++++
>>>>>>   2 files changed, 189 insertions(+), 5 deletions(-)
>>>>>>   create mode 100644 include/linux/pruss.h
>>>>>>
>>>>>> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
>>>>>> index 1777a01fa84e..7a35b400287a 100644
>>>>>> --- a/drivers/remoteproc/pru_rproc.c
>>>>>> +++ b/drivers/remoteproc/pru_rproc.c
>>>>>> @@ -2,12 +2,13 @@
>>>>>>   /*
>>>>>>    * 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>
>>>>>>    */
>>>>>>   #include <linux/bitops.h>
>>>>>> @@ -16,6 +17,7 @@
>>>>>>   #include <linux/module.h>
>>>>>>   #include <linux/of_device.h>
>>>>>>   #include <linux/of_irq.h>
>>>>>> +#include <linux/pruss.h>
>>>>>>   #include <linux/pruss_driver.h>
>>>>>>   #include <linux/remoteproc.h>
>>>>>> @@ -111,6 +113,8 @@ 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)
>>>>>> @@ -126,6 +130,8 @@ 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; /* client access lock */
>>>>>>   	const char *fw_name;
>>>>>>   	unsigned int *mapped_irq;
>>>>>>   	struct pru_irq_rsc *pru_interrupt_map;
>>>>>> @@ -146,6 +152,125 @@ 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 device_node *rproc_np = NULL;
>>>>>> +	struct platform_device *pdev;
>>>>>> +	struct rproc *rproc;
>>>>>> +
>>>>>> +	rproc_np = of_parse_phandle(np, "ti,prus", index);
>>>>>> +	if (!rproc_np || !of_device_is_available(rproc_np))
>>>>>> +		return ERR_PTR(-ENODEV);
>>>>>> +
>>>>>> +	pdev = of_find_device_by_node(rproc_np);
>>>>>> +	of_node_put(rproc_np);
>>>>>> +
>>>>>> +	if (!pdev || !(&pdev->dev) || !((&pdev->dev)->driver))
>>>>>> +		/* probably PRU not yet probed */
>>>>>> +		return ERR_PTR(-EPROBE_DEFER);
>>>>>> +
>>>>>> +	/* make sure it is PRU rproc */
>>>>>> +	if (!is_pru_rproc(&pdev->dev)) {
>>>>>> +		put_device(&pdev->dev);
>>>>>> +		return ERR_PTR(-ENODEV);
>>>>>> +	}
>>>>>> +
>>>>>> +	rproc = platform_get_drvdata(pdev);
>>>>>> +	put_device(&pdev->dev);
>>>>>> +	if (!rproc)
>>>>>> +		return ERR_PTR(-EPROBE_DEFER);
>>>>>> +
>>>>>> +	get_device(&rproc->dev);
>>>>>> +
>>>>>> +	return rproc;
>>>>>> +}
>>>>>> +
>>>>>> +/**
>>>>>> + * 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;
>>>>>> +
>>>>>> +	try_module_get(THIS_MODULE);
>>>>>
>>>>> There should be a module_put() in pru_rproc_put()...
>>>>
>>>> ... and in the error path of this function.
>>>>
>>>>>
>>>>> More comments to come tomorrow.  I'm especially worried about this API racing
>>>>> with a remote processor being removed or detached.
>>>>>
>>>>
>>>> Looking at what is done in wkup_m3_ipc_probe(), it should be possible to call
>>>> rproc_get_by_handle() here and that would make sure the remote processor doesn't
>>>> go away before the end of the function.
>>>>
>>>> More comments to come...
>>
>> It is possible to call rproc_get_by_handle() here instead of
>> __pru_get_proc(), but that would not provide multiple functionality.
>>
>> The API rproc_get_by_handle() returns rproc handle on success, and NULL on
>> failure where as __pru_get_proc() returns ERR_PTR on failure which provides
>> multiple functionality and opportunity for us to distinguish between
>> multiple errors.
>>
>> So we have these three options.
>>
>> 1. If we're using the API rproc_get_by_handle() and we want the multiple
>> ERR_PTR on failure then we will need to change the API rproc_get_by_handle()
>> and also all the functions that uses rproc_get_by_handle().
>>
> 
> Not optimal.
> 
>> 2. Keep the API rproc_get_by_handle() as it is. That will restrict us from
>> using multiple ERR_PTR on different kinds of error.
>>
> 
> Not optimal.
> 
>> 3. Instead of using rproc_get_by_handle(), keep using __pru_get_proc(). This
>> will make sure we have the proper ERR_PTR to retrun for different kinds of
>> errors.
>>
> 
> Unacceptable for the reason I already stated.  
> 
>> Please let me know which option to continue with.
> 
> I suggest building a wrapper that does everything you want around rproc_get_by_phandle().
> 

Sure, I'll do that. I'll share this change in v6 of this patch series.

>>
>> Thanks,
>> Danish
>>
>>
>>>>
>>>>
>>>>> Thanks,
>>>>> Mathieu
>>>>>
>>>>>> +
>>>>>> +	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);
>>>>>> +		return ERR_PTR(-EBUSY);
>>>>>> +	}
>>>>>> +
>>>>>> +	pru->client_np = np;
>>>>>> +
>>>>>> +	mutex_unlock(&pru->lock);
>>>>>> +
>>>>>> +	if (pru_id)
>>>>>> +		*pru_id = pru->id;
>>>>>> +
>>>>>> +	return rproc;
>>>>>> +}
>>>>>> +EXPORT_SYMBOL_GPL(pru_rproc_get);
>>>>>> +
>>>>>> +/**
>>>>>> + * pru_rproc_put() - release the PRU rproc resource
>>>>>> + * @rproc: the rproc resource to release
>>>>>> + *
>>>>>> + * Releases the PRU rproc resource and makes it available to other
>>>>>> + * users.
>>>>>> + */
>>>>>> +void pru_rproc_put(struct rproc *rproc)
>>>>>> +{
>>>>>> +	struct pru_rproc *pru;
>>>>>> +
>>>>>> +	if (IS_ERR_OR_NULL(rproc) || !is_pru_rproc(rproc->dev.parent))
>>>>>> +		return;
>>>>>> +
>>>>>> +	pru = rproc->priv;
>>>>>> +
>>>>>> +	mutex_lock(&pru->lock);
>>>>>> +
>>>>>> +	if (!pru->client_np) {
>>>>>> +		mutex_unlock(&pru->lock);
>>>>>> +		return;
>>>>>> +	}
>>>>>> +
>>>>>> +	pru->client_np = NULL;
>>>>>> +	mutex_unlock(&pru->lock);
>>>>>> +
>>>>>> +	put_device(&rproc->dev);
>>>>>> +}
>>>>>> +EXPORT_SYMBOL_GPL(pru_rproc_put);
>>>>>> +
>>>>>>   static inline u32 pru_debug_read_reg(struct pru_rproc *pru, unsigned int reg)
>>>>>>   {
>>>>>>   	return readl_relaxed(pru->mem_regions[PRU_IOMEM_DEBUG].va + reg);
>>>>>> @@ -438,7 +563,7 @@ static void *pru_d_da_to_va(struct pru_rproc *pru, u32 da, size_t len)
>>>>>>   	dram0 = pruss->mem_regions[PRUSS_MEM_DRAM0];
>>>>>>   	dram1 = pruss->mem_regions[PRUSS_MEM_DRAM1];
>>>>>>   	/* PRU1 has its local RAM addresses reversed */
>>>>>> -	if (pru->id == 1)
>>>>>> +	if (pru->id == PRUSS_PRU1)
>>>>>>   		swap(dram0, dram1);
>>>>>>   	shrd_ram = pruss->mem_regions[PRUSS_MEM_SHRD_RAM2];
>>>>>> @@ -747,14 +872,14 @@ static int pru_rproc_set_id(struct pru_rproc *pru)
>>>>>>   	case RTU0_IRAM_ADDR_MASK:
>>>>>>   		fallthrough;
>>>>>>   	case PRU0_IRAM_ADDR_MASK:
>>>>>> -		pru->id = 0;
>>>>>> +		pru->id = PRUSS_PRU0;
>>>>>>   		break;
>>>>>>   	case TX_PRU1_IRAM_ADDR_MASK:
>>>>>>   		fallthrough;
>>>>>>   	case RTU1_IRAM_ADDR_MASK:
>>>>>>   		fallthrough;
>>>>>>   	case PRU1_IRAM_ADDR_MASK:
>>>>>> -		pru->id = 1;
>>>>>> +		pru->id = PRUSS_PRU1;
>>>>>>   		break;
>>>>>>   	default:
>>>>>>   		ret = -EINVAL;
>>>>>> @@ -816,6 +941,8 @@ static int pru_rproc_probe(struct platform_device *pdev)
>>>>>>   	pru->pruss = platform_get_drvdata(ppdev);
>>>>>>   	pru->rproc = rproc;
>>>>>>   	pru->fw_name = fw_name;
>>>>>> +	pru->client_np = NULL;
>>>>>> +	mutex_init(&pru->lock);
>>>>>>   	for (i = 0; i < ARRAY_SIZE(mem_names); i++) {
>>>>>>   		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>>>>>> @@ -903,7 +1030,7 @@ MODULE_DEVICE_TABLE(of, pru_rproc_match);
>>>>>>   static struct platform_driver pru_rproc_driver = {
>>>>>>   	.driver = {
>>>>>> -		.name   = "pru-rproc",
>>>>>> +		.name   = PRU_RPROC_DRVNAME,
>>>>>>   		.of_match_table = pru_rproc_match,
>>>>>>   		.suppress_bind_attrs = true,
>>>>>>   	},
>>>>>> @@ -915,5 +1042,6 @@ module_platform_driver(pru_rproc_driver);
>>>>>>   MODULE_AUTHOR("Suman Anna <s-anna@...com>");
>>>>>>   MODULE_AUTHOR("Andrew F. Davis <afd@...com>");
>>>>>>   MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>");
>>>>>> +MODULE_AUTHOR("Puranjay Mohan <p-mohan@...com>");
>>>>>>   MODULE_DESCRIPTION("PRU-ICSS Remote Processor Driver");
>>>>>>   MODULE_LICENSE("GPL v2");
>>>>>> diff --git a/include/linux/pruss.h b/include/linux/pruss.h
>>>>>> new file mode 100644
>>>>>> index 000000000000..fdc719b43db0
>>>>>> --- /dev/null
>>>>>> +++ b/include/linux/pruss.h
>>>>>> @@ -0,0 +1,56 @@
>>>>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>>>>> +/**
>>>>>> + * PRU-ICSS Subsystem user interfaces
>>>>>> + *
>>>>>> + * Copyright (C) 2015-2022 Texas Instruments Incorporated - http://www.ti.com
>>>>>> + *	Suman Anna <s-anna@...com>
>>>>>> + */
>>>>>> +
>>>>>> +#ifndef __LINUX_PRUSS_H
>>>>>> +#define __LINUX_PRUSS_H
>>>>>> +
>>>>>> +#include <linux/device.h>
>>>>>> +#include <linux/types.h>
>>>>>> +
>>>>>> +#define PRU_RPROC_DRVNAME "pru-rproc"
>>>>>> +
>>>>>> +/*
>>>>>> + * enum pruss_pru_id - PRU core identifiers
>>>>>> + */
>>>>>> +enum pruss_pru_id {
>>>>>> +	PRUSS_PRU0 = 0,
>>>>>> +	PRUSS_PRU1,
>>>>>> +	PRUSS_NUM_PRUS,
>>>>>> +};
>>>>>> +
>>>>>> +struct device_node;
>>>>>> +
>>>>>> +#if IS_ENABLED(CONFIG_PRU_REMOTEPROC)
>>>>>> +
>>>>>> +struct rproc *pru_rproc_get(struct device_node *np, int index,
>>>>>> +			    enum pruss_pru_id *pru_id);
>>>>>> +void pru_rproc_put(struct rproc *rproc);
>>>>>> +
>>>>>> +#else
>>>>>> +
>>>>>> +static inline struct rproc *
>>>>>> +pru_rproc_get(struct device_node *np, int index, enum pruss_pru_id *pru_id)
>>>>>> +{
>>>>>> +	return ERR_PTR(-EOPNOTSUPP);
>>>>>> +}
>>>>>> +
>>>>>> +static inline void pru_rproc_put(struct rproc *rproc) { }
>>>>>> +
>>>>>> +#endif /* CONFIG_PRU_REMOTEPROC */
>>>>>> +
>>>>>> +static inline bool is_pru_rproc(struct device *dev)
>>>>>> +{
>>>>>> +	const char *drv_name = dev_driver_string(dev);
>>>>>> +
>>>>>> +	if (strncmp(drv_name, PRU_RPROC_DRVNAME, sizeof(PRU_RPROC_DRVNAME)))
>>>>>> +		return false;
>>>>>> +
>>>>>> +	return true;
>>>>>> +}
>>>>>> +
>>>>>> +#endif /* __LINUX_PRUSS_H */
>>>>>> -- 
>>>>>> 2.17.1
>>>>>>

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