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cxl: Implement an ioctl to fetch afu card-id, offset-id and mode

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Given a file descriptor on an afu device, libcxl currently uses the
major/minor number obtained from fstat on the fd to construct path to
the afu's sysfs directory. However it is possible that rather than using
one of the device in /dev/cxl, a kernel driver creates its own device
which export generic cxl interface to the userspace. This causes
problems with libcxl as it tries to use a wrong major/minor number to
construct the sysfs path and fail.

So this patch introduces a new ioctl called CXL_IOCTL_GET_AFU_ID on the
afu file descriptor to fetch the cxl_afu_id struct that holds the
card/offset-id and mode information. These info is then used by libcxl to
construct the correct path to the afu sysfs directory.

Testing:
	- Build against pseries be/le configs
	- Testing with corresponding libcxl changes to verify that it constructs
	  right sysfs path to the afu.

Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Vaibhav Jain
2015-04-29 15:47:23 +05:30
committed by Michael Ellerman
parent 989898b707
commit 27d4dc7116
3 changed files with 44 additions and 2 deletions
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22
include/uapi/misc/cxl.h
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@@ -32,10 +32,32 @@ struct cxl_ioctl_start_work {
#define CXL_START_WORK_ALL (CXL_START_WORK_AMR |\
CXL_START_WORK_NUM_IRQS)
/* Possible modes that an afu can be in */
#define CXL_MODE_DEDICATED 0x1
#define CXL_MODE_DIRECTED 0x2
/* possible flags for the cxl_afu_id flags field */
#define CXL_AFUID_FLAG_SLAVE 0x1 /* In directed-mode afu is in slave mode */
struct cxl_afu_id {
__u64 flags; /* One of CXL_AFUID_FLAG_X */
__u32 card_id;
__u32 afu_offset;
__u32 afu_mode; /* one of the CXL_MODE_X */
__u32 reserved1;
__u64 reserved2;
__u64 reserved3;
__u64 reserved4;
__u64 reserved5;
__u64 reserved6;
};
/* ioctl numbers */
#define CXL_MAGIC 0xCA
#define CXL_IOCTL_START_WORK _IOW(CXL_MAGIC, 0x00, struct cxl_ioctl_start_work)
#define CXL_IOCTL_GET_PROCESS_ELEMENT _IOR(CXL_MAGIC, 0x01, __u32)
#define CXL_IOCTL_GET_AFU_ID _IOR(CXL_MAGIC, 0x02, struct cxl_afu_id)
#define CXL_READ_MIN_SIZE 0x1000 /* 4K */