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Message-ID: <20c544ef-40b3-dcbc-1f29-aac140725b57@ti.com>
Date:   Fri, 15 Jul 2022 11:52:47 +0530
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Subject: Re: [PATCH v5 2/6] remoteproc: pru: Add APIs to get and put the PRU
 cores
Content-Language: en-US
To:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        Md Danish Anwar <danishanwar@ti.com>
CC:     <linux-kernel@vger.kernel.org>, <bjorn.andersson@linaro.org>,
        <krzysztof.kozlowski+dt@linaro.org>,
        <linux-remoteproc@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <nm@ti.com>, <ssantosh@kernel.org>, <s-anna@ti.com>,
        <linux-arm-kernel@lists.infradead.org>, <rogerq@kernel.org>,
        <grygorii.strashko@ti.com>, <vigneshr@ti.com>, <robh@kernel.org>
References: <20220607045650.4999-1-p-mohan@ti.com>
 <20220607045650.4999-3-p-mohan@ti.com> <20220712175949.GB2945984@p14s>
 <20220714172015.GA3106020@p14s>
From:   Kishon Vijay Abraham I <kishon@ti.com>
In-Reply-To: <20220714172015.GA3106020@p14s>
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+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@ti.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@ti.com>
>>> Signed-off-by: Suman Anna <s-anna@ti.com>
>>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>>> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
>>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
>>> Co-developed-by: Puranjay Mohan <p-mohan@ti.com>
>>> Signed-off-by: Puranjay Mohan <p-mohan@ti.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@ti.com>
>>>   *	Andrew F. Davis <afd@ti.com>
>>>   *	Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org> for Texas Instruments
>>> + *	Puranjay Mohan <p-mohan@ti.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...
> 
> 
>> 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@ti.com>");
>>>  MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
>>>  MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>");
>>> +MODULE_AUTHOR("Puranjay Mohan <p-mohan@ti.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@ti.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
>>>