IOMMUs currently have no common representation to userspace, most seem to have no representation at all aside from a few printks on bootup. There are, however, features of IOMMUs that are useful to know about. For instance, the IOMMU might support superpages, making use of processor large/huge pages more important in a device assignment scenario. It's also useful to create cross links between devices and IOMMU hardware units, so that users might be able to load balance their devices to avoid thrashing a single hardware unit.
This patch adds a registration and de-registration interface as well as device linking, making it very lightweight for an IOMMU driver to add basic support. IOMMU drivers can provide additional attributes automatically by using an attribute_group. The attributes exposed are expected to be relatively device specific, the means to retrieve them certainly are. So there are currently no common attributes for the new iommu_class created here. Signed-off-by: Alex Williamson <[email protected]> --- drivers/iommu/Makefile | 1 drivers/iommu/iommu-sysfs.c | 147 +++++++++++++++++++++++++++++++++++++++++++ include/linux/iommu.h | 28 ++++++++ 3 files changed, 176 insertions(+) create mode 100644 drivers/iommu/iommu-sysfs.c diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile index 5d58bf1..437c231 100644 --- a/drivers/iommu/Makefile +++ b/drivers/iommu/Makefile @@ -1,5 +1,6 @@ obj-$(CONFIG_IOMMU_API) += iommu.o obj-$(CONFIG_IOMMU_API) += iommu-traces.o +obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o obj-$(CONFIG_OF_IOMMU) += of_iommu.o obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o msm_iommu_dev.o obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o diff --git a/drivers/iommu/iommu-sysfs.c b/drivers/iommu/iommu-sysfs.c new file mode 100644 index 0000000..123f20c --- /dev/null +++ b/drivers/iommu/iommu-sysfs.c @@ -0,0 +1,147 @@ +#include <linux/device.h> +#include <linux/iommu.h> +#include <linux/module.h> + +struct iommu_device { + struct device dev; + struct kobject *devices; +}; + +#define to_iommu_device(dev) container_of(dev, struct iommu_device, dev) + +static void iommu_release_device(struct device *dev) +{ + struct iommu_device *iommu = to_iommu_device(dev); + kobject_put(iommu->devices); + kfree(iommu); +} + +static struct class iommu_class = { + .name = "iommu", + .dev_release = iommu_release_device, +}; + +static int __init iommu_dev_init(void) +{ + return class_register(&iommu_class); +} +postcore_initcall(iommu_dev_init); + +static int __match_platform_data(struct device *dev, const void *platform_data) +{ + return dev->platform_data == platform_data; +} + +int iommu_register_device(struct device *parent, const char *name, + const struct attribute_group **groups, + void *platform_data) +{ + struct device *dev; + struct iommu_device *iommu; + int ret; + + dev = class_find_device(&iommu_class, NULL, + platform_data, __match_platform_data); + if (dev) { + put_device(dev); + return -EEXIST; + } + + iommu = kzalloc(sizeof(*iommu), GFP_KERNEL); + if (!iommu) + return -ENOMEM; + + device_initialize(&iommu->dev); + + iommu->dev.class = &iommu_class; + iommu->dev.parent = parent; + dev_set_name(&iommu->dev, "%s", name); + iommu->dev.groups = groups; + iommu->dev.platform_data = platform_data; + + ret = device_add(&iommu->dev); + if (ret) + goto error; + + iommu->devices = kobject_create_and_add("devices", &iommu->dev.kobj); + if (!iommu->devices) { + ret = -ENOMEM; + goto error; + } + + /* devices holds ref */ + put_device(&iommu->dev); + + return 0; + +error: + pr_warn("Unable to register iommu device %s\n", name); + put_device(&iommu->dev); + + return ret; +} + +void iommu_unregister_device(void *platform_data) +{ + struct device *dev; + struct iommu_device *iommu; + + dev = class_find_device(&iommu_class, NULL, + platform_data, __match_platform_data); + if (!dev) + return; + + iommu = to_iommu_device(dev); + /* class_find_device gives us a new ref to put in device_unregister */ + device_unregister(&iommu->dev); + kobject_put(iommu->devices); +} + +int iommu_device_link(const void *platform_data, struct device *link) +{ + struct device *dev; + struct iommu_device *iommu; + int ret; + + dev = class_find_device(&iommu_class, NULL, + platform_data, __match_platform_data); + if (!dev) + return -ENODEV; + + iommu = to_iommu_device(dev); + + ret = sysfs_create_link(&link->kobj, &dev->kobj, "iommu"); + if (ret) + goto error; + + ret = sysfs_create_link_nowarn(iommu->devices, + &link->kobj, dev_name(link)); + if (ret) { + sysfs_remove_link(&link->kobj, "iommu"); + goto error; + } + + kobject_get(iommu->devices); +error: + put_device(dev); + return ret; +} + +void iommu_device_unlink(const void *platform_data, struct device *link) +{ + struct device *dev; + struct iommu_device *iommu; + + dev = class_find_device(&iommu_class, NULL, + platform_data, __match_platform_data); + if (!dev) + return; + + iommu = to_iommu_device(dev); + + sysfs_remove_link(iommu->devices, dev_name(link)); + sysfs_remove_link(&link->kobj, "iommu"); + + kobject_put(iommu->devices); + put_device(dev); +} diff --git a/include/linux/iommu.h b/include/linux/iommu.h index b96a5b2..e9bd3a0 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -186,6 +186,12 @@ extern int iommu_domain_get_attr(struct iommu_domain *domain, enum iommu_attr, void *data); extern int iommu_domain_set_attr(struct iommu_domain *domain, enum iommu_attr, void *data); +extern int iommu_register_device(struct device *parent, const char *name, + const struct attribute_group **groups, + void *platform_data); +extern void iommu_unregister_device(void *platform_data); +extern int iommu_device_link(const void *platform_data, struct device *link); +extern void iommu_device_unlink(const void *platform_data, struct device *link); /* Window handling function prototypes */ extern int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr, @@ -396,6 +402,28 @@ static inline int iommu_domain_set_attr(struct iommu_domain *domain, return -EINVAL; } +static inline int iommu_register_device(struct device *parent, const char *name, + const struct attribute_group **groups, + void *platform_data) +{ + return 0; +} + +static inline void iommu_unregister_device(void *platform_data) +{ +} + +static inline int iommu_device_link(const void *platform_data, + struct device *link) +{ + return 0; +} + +static inline void iommu_device_unlink(const void *platform_data, + struct device *link) +{ +} + #endif /* CONFIG_IOMMU_API */ #endif /* __LINUX_IOMMU_H */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
