[RFC PATCH 1/5] vfio_platform: Introduce vfio_platform_get_region helper

[Eric Auger <eric.auger@redhat.com>]

Reset modules need to access some specific regions. It may
easier and safer to refer to those regions using their
name instead of relying on their index.

So let's introduce a helper that looks for the
struct vfio_platform_region with a given name.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

I don't know if reg names described in binding yaml are guaranteed to
appear in the listed order. I guess no, hence the reg-names.
In my case, for the host tegra234 dt node, regs I even observe regs that
are not documented in the yaml:
mac, xpcs, macsec-base, hypervisor whereas yaml only describes
hypervisor, mac, xpcs
---
 drivers/vfio/platform/vfio_platform_common.c  | 14 ++++++++++++++
 drivers/vfio/platform/vfio_platform_private.h |  5 +++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index e53757d1d095..6861f977fd5b 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -153,6 +153,7 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
 		vdev->regions[i].addr = res->start;
 		vdev->regions[i].size = resource_size(res);
 		vdev->regions[i].flags = 0;
+		vdev->regions[i].name = res->name;
 
 		switch (resource_type(res)) {
 		case IORESOURCE_MEM:
@@ -188,6 +189,19 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
 	return -EINVAL;
 }
 
+struct vfio_platform_region*
+vfio_platform_get_region(struct vfio_platform_device *vdev, const char *name)
+{
+	int i;
+
+	for (i = 0; i < vdev->num_regions; i++) {
+		if (!strcmp(vdev->regions[i].name, name))
+			return &vdev->regions[i];
+	}
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_platform_get_region);
+
 static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
 {
 	int i;
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 8d8fab516849..20d67634bc41 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -37,6 +37,7 @@ struct vfio_platform_region {
 	resource_size_t		size;
 	u32			flags;
 	u32			type;
+	const char		*name;
 #define VFIO_PLATFORM_REGION_TYPE_MMIO	1
 #define VFIO_PLATFORM_REGION_TYPE_PIO	2
 	void __iomem		*ioaddr;
@@ -104,6 +105,10 @@ int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
 void __vfio_platform_register_reset(struct vfio_platform_reset_node *n);
 void vfio_platform_unregister_reset(const char *compat,
 				    vfio_platform_reset_fn_t fn);
+
+struct vfio_platform_region *
+vfio_platform_get_region(struct vfio_platform_device *vdev, const char *name);
+
 #define vfio_platform_register_reset(__compat, __reset)		\
 static struct vfio_platform_reset_node __reset ## _node = {	\
 	.owner = THIS_MODULE,					\
-- 
2.41.0