Re: [PATCH v6 05/14] ACPI: platform-msi: retrieve dev id from IORT

From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linuxarm@huawei.com,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg KH <gregkh@linuxfoundation.org>,
	Tomasz Nowicki <tn@semihalf.com>, Ma Jun <majun258@huawei.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Agustin Vega-Frias <agustinv@codeaurora.org>,
	Sinan Kaya <okaya@codeaurora.org>,
	charles.garcia-tobin@arm.com, huxinwei@huawei.com,
	yimin@huawei.com, Jon Masters <jcm@redhat.com>
Subject: Re: [PATCH v6 05/14] ACPI: platform-msi: retrieve dev id from IORT
Date: Wed, 4 Jan 2017 19:18:05 +0000	[thread overview]
Message-ID: <20170104191805.GE8604@red-moon> (raw)
In-Reply-To: <1483363905-2806-6-git-send-email-hanjun.guo@linaro.org>

On Mon, Jan 02, 2017 at 09:31:36PM +0800, Hanjun Guo wrote:
> For devices connecting to ITS, it needs dev id to identify
> itself, and this dev id is represented in the IORT table in
> named componant node [1] for platform devices, so in this
> patch we will scan the IORT to retrieve device's dev id.
> 
> Introduce iort_pmsi_get_dev_id() with pointer dev passed
> in for that purpose.
> 
> [1]: https://static.docs.arm.com/den0049/b/DEN0049B_IO_Remapping_Table.pdf
> 
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> Tested-by: Sinan Kaya <okaya@codeaurora.org>
> Tested-by: Majun <majun258@huawei.com>
> Tested-by: Xinwei Kong <kong.kongxinwei@hisilicon.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Tomasz Nowicki <tn@semihalf.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> ---
>  drivers/acpi/arm64/iort.c                     | 26 ++++++++++++++++++++++++++
>  drivers/irqchip/irq-gic-v3-its-platform-msi.c |  4 +++-
>  include/linux/acpi_iort.h                     |  8 ++++++++
>  3 files changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 174e983..ab7bae7 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -444,6 +444,32 @@ u32 iort_msi_map_rid(struct device *dev, u32 req_id)
>  }
>  
>  /**
> + * iort_pmsi_get_dev_id() - Get the device id for a device
> + * @dev: The device for which the mapping is to be done.
> + * @dev_id: The device ID found.
> + *
> + * Returns: 0 for successful find a dev id, errors otherwise
> + */
> +int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
> +{
> +	struct acpi_iort_node *node;
> +
> +	if (!iort_table)
> +		return -ENODEV;
> +
> +	node = iort_find_dev_node(dev);
> +	if (!node) {
> +		dev_err(dev, "can't find related IORT node\n");
> +		return -ENODEV;
> +	}
> +
> +	if(!iort_node_get_id(node, dev_id, IORT_MSI_TYPE, 0))

I disagree with this approach. For named components we know that
there are always two steps involved (second optional):

(1) Retrieve the initial id (this may well provide the final mapping)
(2) Map the id (optional if (1) represents the map type we need)

That's the reason why I kept iort_node_get_id() and iort_node_map_rid()
separated.

Now, what we can do is to create an iort_node_map_id() function that is
PCI agnostic (ie rename rid to id :)), whose rid_in is either a PCI RID
or the outcome of a previous call to iort_node_get_id() for named
components, that's in my opinion cleaner.

It would be even cleaner if you passed a type_mask (or write a
wrapper function for that) that is:

(IORT_MSI_TYPE | IORT_IOMMU_TYPE)

and we just use the returned parent pointer to check if the mapping
providing the initial id correspond to the type we are looking for (eg
ITS) or we need to map the retrieved initial id any further, with
iort_node_map_id(), to get to the final identifier.

Thoughts ?

Thanks,
Lorenzo

> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +/**
>   * iort_dev_find_its_id() - Find the ITS identifier for a device
>   * @dev: The device.
>   * @req_id: Device's Requster ID
> diff --git a/drivers/irqchip/irq-gic-v3-its-platform-msi.c b/drivers/irqchip/irq-gic-v3-its-platform-msi.c
> index 3c94278..16587a9 100644
> --- a/drivers/irqchip/irq-gic-v3-its-platform-msi.c
> +++ b/drivers/irqchip/irq-gic-v3-its-platform-msi.c
> @@ -15,6 +15,7 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/acpi_iort.h>
>  #include <linux/device.h>
>  #include <linux/msi.h>
>  #include <linux/of.h>
> @@ -56,7 +57,8 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
>  
>  	msi_info = msi_get_domain_info(domain->parent);
>  
> -	ret = of_pmsi_get_dev_id(domain, dev, &dev_id);
> +	ret = dev->of_node ? of_pmsi_get_dev_id(domain, dev, &dev_id) :
> +		iort_pmsi_get_dev_id(dev, &dev_id);
>  	if (ret)
>  		return ret;
>  
> diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
> index 77e0809..ef99fd52 100644
> --- a/include/linux/acpi_iort.h
> +++ b/include/linux/acpi_iort.h
> @@ -33,6 +33,7 @@
>  void acpi_iort_init(void);
>  bool iort_node_match(u8 type);
>  u32 iort_msi_map_rid(struct device *dev, u32 req_id);
> +int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id);
>  struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
>  /* IOMMU interface */
>  void iort_set_dma_mask(struct device *dev);
> @@ -42,9 +43,16 @@ static inline void acpi_iort_init(void) { }
>  static inline bool iort_node_match(u8 type) { return false; }
>  static inline u32 iort_msi_map_rid(struct device *dev, u32 req_id)
>  { return req_id; }
> +
>  static inline struct irq_domain *iort_get_device_domain(struct device *dev,
>  							u32 req_id)
>  { return NULL; }
> +
> +static inline int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
> +{
> +	return -ENODEV;
> +}
> +
>  /* IOMMU interface */
>  static inline void iort_set_dma_mask(struct device *dev) { }
>  static inline
> -- 
> 1.9.1
> 