drivers/base: Add MSI domain support for non-PCI devices

With the msi_list and the msi_domain properties now being at the
generic device level, it is starting to be relatively easy to offer
a generic way of providing non-PCI MSIs.

The two major hurdles with this idea are:

- Lack of global ID that identifies a device: this is worked around by
  having a global ID allocator for each device that gets enrolled in
  the platform MSI subsystem

- Lack of standard way to write the message in the generating device.
  This is solved by mandating driver code to provide a write_msg
  callback, so that everyone can have their own square wheel

Apart from that, the API is fairly straightforward:

- platform_msi_create_irq_domain creates an MSI domain that gets
  tagged with DOMAIN_BUS_PLATFORM_MSI

- platform_msi_domain_alloc_irqs allocate MSIs for a given device,
  populating the msi_list

- platform_msi_domain_free_irqs does what is written on the tin

[ tglx: Created a seperate struct platform_msi_desc and added
  	kerneldoc entries ]

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Ma Jun <majun258@huawei.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Duc Dang <dhdang@apm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1438091186-10244-10-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/msi.h b/include/linux/msi.h
index f83c87e..809b749 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -15,9 +15,23 @@ extern int pci_msi_ignore_mask;
 struct irq_data;
 struct msi_desc;
 struct pci_dev;
+struct platform_msi_priv_data;
 void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
 
+typedef void (*irq_write_msi_msg_t)(struct msi_desc *desc,
+				    struct msi_msg *msg);
+
+/**
+ * platform_msi_desc - Platform device specific msi descriptor data
+ * @msi_priv_data:	Pointer to platform private data
+ * @msi_index:		The index of the MSI descriptor for multi MSI
+ */
+struct platform_msi_desc {
+	struct platform_msi_priv_data	*msi_priv_data;
+	u16				msi_index;
+};
+
 /**
  * struct msi_desc - Descriptor structure for MSI based interrupts
  * @list:	List head for management
@@ -36,6 +50,7 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
  * @default_irq:[PCI MSI/X] The default pre-assigned non-MSI irq
  * @mask_pos:	[PCI MSI]   Mask register position
  * @mask_base:	[PCI MSI-X] Mask register base address
+ * @platform:	[platform]  Platform device specific msi descriptor data
  */
 struct msi_desc {
 	/* Shared device/bus type independent data */
@@ -71,6 +86,7 @@ struct msi_desc {
 		 * anonymous for now as it would require an immediate
 		 * tree wide cleanup.
 		 */
+		struct platform_msi_desc platform;
 	};
 };
 
@@ -257,6 +273,12 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
 void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev);
 struct msi_domain_info *msi_get_domain_info(struct irq_domain *domain);
 
+struct irq_domain *platform_msi_create_irq_domain(struct device_node *np,
+						  struct msi_domain_info *info,
+						  struct irq_domain *parent);
+int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
+				   irq_write_msi_msg_t write_msi_msg);
+void platform_msi_domain_free_irqs(struct device *dev);
 #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */
 
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN