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Date:   Thu, 20 Jan 2022 16:03:57 +0100
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Subject: Re: [PATCH v4 3/9] spi: Support selection of the index of the ACPI
 Spi Resource before alloc
Content-Language: en-US
To:     Stefan Binding <sbinding@opensource.cirrus.com>,
        Mark Brown <broonie@kernel.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, Mark Gross <markgross@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>
Cc:     alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        linux-spi@vger.kernel.org, linux-acpi@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, patches@opensource.cirrus.com
References: <20220120134326.5295-1-sbinding@opensource.cirrus.com>
 <20220120134326.5295-4-sbinding@opensource.cirrus.com>
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20220120134326.5295-4-sbinding@opensource.cirrus.com>
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Precedence: bulk

Hi Stefan,

On 1/20/22 14:43, Stefan Binding wrote:
> If a node contains more than one Spi Resources, it may be necessary to
> use an index to select which one you want to allocate a spi device for.
> 
> Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
> ---
>  drivers/spi/spi.c       | 56 +++++++++++++++++++++++++++++++++++------
>  include/linux/spi/spi.h |  6 +++--
>  2 files changed, 52 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 13f4701f0694..898cc9931490 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -2320,6 +2320,9 @@ struct acpi_spi_lookup {
>  	int			irq;
>  	u8			bits_per_word;
>  	u8			chip_select;
> +	int			n;
> +	int			index;
> +	int			irq_index;
>  };
>  
>  static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
> @@ -2351,6 +2354,8 @@ static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
>  		lookup->mode |= SPI_CPHA;
>  }
>  
> +static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev);
> +
>  static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
>  {
>  	struct acpi_spi_lookup *lookup = data;
> @@ -2364,14 +2369,35 @@ static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
>  		sb = &ares->data.spi_serial_bus;
>  		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
>  
> +			if (lookup->index != -1 && lookup->n++ != lookup->index)
> +				return 1;
> +
> +			if (lookup->index == -1 && !ctlr)
> +				return -ENODEV;
> +
>  			status = acpi_get_handle(NULL,
>  						 sb->resource_source.string_ptr,
>  						 &parent_handle);
>  
> -			if (ACPI_FAILURE(status) ||
> -			    ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
> +			if (ACPI_FAILURE(status))
>  				return -ENODEV;
>  
> +			if (ctlr) {
> +				if (ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
> +					return -ENODEV;
> +			} else {
> +				struct acpi_device *adev;
> +
> +				if (acpi_bus_get_device(parent_handle, &adev))
> +					return -ENODEV;
> +
> +				ctlr = acpi_spi_find_controller_by_adev(adev);
> +				if (!ctlr)
> +					return -ENODEV;
> +
> +				lookup->ctlr = ctlr;
> +			}
> +
>  			/*
>  			 * ACPI DeviceSelection numbering is handled by the
>  			 * host controller driver in Windows and can vary

All of the above looks good to me.

> @@ -2402,7 +2428,7 @@ static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
>  	} else if (lookup->irq < 0) {
>  		struct resource r;
>  
> -		if (acpi_dev_resource_interrupt(ares, 0, &r))
> +		if (acpi_dev_resource_interrupt(ares, lookup->irq_index, &r))
>  			lookup->irq = r.start;
>  	}
>  

I think that this does not do what you want it to do. Quoting drivers/acpi/resource.c:

bool acpi_dev_resource_interrupt(struct acpi_resource *ares, int index,
                                 struct resource *res)
{
        struct acpi_resource_irq *irq;
        struct acpi_resource_extended_irq *ext_irq;

        switch (ares->type) {
        case ACPI_RESOURCE_TYPE_IRQ:
                /*
                 * Per spec, only one interrupt per descriptor is allowed in
                 * _CRS, but some firmware violates this, so parse them all.
                 */
                irq = &ares->data.irq;
                if (index >= irq->interrupt_count) {
                        irqresource_disabled(res, 0);
                        return false;
                }

So now you are actually adding an index into a single:

                    Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive, ,, )
                    {
                        0x00000008,
                    }

ACPI Resource, which typically (as shown here) only has 1 interrupt, I guess
what you want is the nth resource of type ACPI_RESOURCE_TYPE_IRQ or
ACPI_RESOURCE_TYPE_EXTENDED_IRQ.

So to make this work you should combine this with a separate irq_n
for irq_index, increment that on acpi_dev_resource_interrupt() success
and then only set lookup->irq = r.start; when irq_n == irq_index.

But since the bus-multi-inst code already has its own irq getting code
this is not really necessary, I would just drop the new irq_index field;
and then also drop the "if (spi_dev->irq < 0)" condition for calling
bmi_get_irq() in "[PATCH v4 7/9] platform/x86: bus-multi-instantiate:
Add SPI support"

Note that for the CS35L41 that if is always true already since
that is using a GpioInt resource and acpi_dev_resource_interrupt()
does not support those.

TL;DR: please drop the new irq_index fiels and just leave the
related bits as is.


> @@ -2414,14 +2440,22 @@ static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
>   * acpi_spi_device_alloc - Allocate a spi device, and fill it in with ACPI information
>   * @ctlr: controller to which the spi device belongs
>   * @adev: ACPI Device for the spi device
> + * @index: Index of the spi resource inside the ACPI Node
> + * @irq_index: Index of the GPIO resource for the IRQ inside the ACPI Node
>   *
>   * This should be used to allocate a new spi device from and ACPI Node.
>   * The caller is responsible for calling spi_add_device to register the spi device.
>   *
> + * If ctlr is set to NULL, the Controller for the spi device will be looked up
> + * using the resource.
> + * If index is set to -1, index is not used.
> + * Note: If index is -1, ctlr must be set.
> + *
>   * Return: a pointer to the new device, or ERR_PTR on error.
>   */
>  struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
> -					 struct acpi_device *adev)
> +					 struct acpi_device *adev,
> +					 int index, int irq_index)
>  {
>  	acpi_handle parent_handle = NULL;
>  	struct list_head resource_list;
> @@ -2429,8 +2463,14 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
>  	struct spi_device *spi;
>  	int ret;
>  
> +	if (!ctlr && index == -1)
> +		return ERR_PTR(-EINVAL);
> +
>  	lookup.ctlr		= ctlr;
>  	lookup.irq		= -1;
> +	lookup.index		= index;
> +	lookup.n		= 0;
> +	lookup.irq_index	= irq_index;
>  
>  	INIT_LIST_HEAD(&resource_list);
>  	ret = acpi_dev_get_resources(adev, &resource_list,
> @@ -2443,7 +2483,7 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
>  
>  	if (!lookup.max_speed_hz &&
>  	    ACPI_SUCCESS(acpi_get_parent(adev->handle, &parent_handle)) &&
> -	    ACPI_HANDLE(ctlr->dev.parent) == parent_handle) {
> +	    ACPI_HANDLE(lookup.ctlr->dev.parent) == parent_handle) {
>  		/* Apple does not use _CRS but nested devices for SPI slaves */
>  		acpi_spi_parse_apple_properties(adev, &lookup);
>  	}
> @@ -2451,9 +2491,9 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
>  	if (!lookup.max_speed_hz)
>  		return ERR_PTR(-ENODEV);
>  
> -	spi = spi_alloc_device(ctlr);
> +	spi = spi_alloc_device(lookup.ctlr);
>  	if (!spi) {
> -		dev_err(&ctlr->dev, "failed to allocate SPI device for %s\n",
> +		dev_err(&lookup.ctlr->dev, "failed to allocate SPI device for %s\n",
>  			dev_name(&adev->dev));
>  		return ERR_PTR(-ENOMEM);
>  	}
> @@ -2478,7 +2518,7 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
>  	    acpi_device_enumerated(adev))
>  		return AE_OK;
>  
> -	spi = acpi_spi_device_alloc(ctlr, adev);
> +	spi = acpi_spi_device_alloc(ctlr, adev, -1, 0);
>  	if (IS_ERR(spi)) {
>  		if (PTR_ERR(spi) == -ENOMEM)
>  			return AE_NO_MEMORY;
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 200725692b93..1a34fd0f6ca2 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -762,10 +762,12 @@ extern void spi_unregister_controller(struct spi_controller *ctlr);
>  
>  #if IS_ENABLED(CONFIG_ACPI)
>  extern struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
> -						struct acpi_device *adev);
> +						struct acpi_device *adev,
> +						int index, int irq_index);
>  #else
>  static inline struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
> -						       struct acpi_device *adev);
> +						       struct acpi_device *adev,
> +						       int index, int irq_index);
>  {
>  	return ERR_PTR(-EOPNOTSUPP);
>  }
> 


Like with my review of patch 2/9, I don't think we need stubs here.

Regards,

Hans