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

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>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index a1cee4767ec6..9f280e3e742e 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -315,8 +315,6 @@ static const cxl_p2n_reg_t CXL_PSL_WED_An     = {0x0A0};
 #define CXL_MAX_SLICES 4
 #define MAX_AFU_MMIO_REGS 3
 
-#define CXL_MODE_DEDICATED   0x1
-#define CXL_MODE_DIRECTED    0x2
 #define CXL_MODE_TIME_SLICED 0x4
 #define CXL_SUPPORTED_MODES (CXL_MODE_DEDICATED | CXL_MODE_DIRECTED)