[PATCH 6/7] ocxl: Add an IOCTL so userspace knows which platform the kernel requires

[Alastair D'Silva]

From: Alastair D'Silva <alast...@d-silva.org>

In order for a userspace AFU driver to call the Power9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..5a9f4f85aafd 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context 
*ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_platform(struct ocxl_context *ctx,
+               struct ocxl_ioctl_platform __user *uarg)
+{
+       struct ocxl_ioctl_platform arg;
+
+       memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+       if (cpu_has_feature(CPU_FTR_P9_TIDR))
+               arg.flags[0] |= OCXL_IOCTL_PLATFORM_FLAGS0_P9_WAIT;
+#endif
+
+       if (copy_to_user(uarg, &arg, sizeof(arg)))
+               return -EFAULT;
+
+       return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :                        
\
                        x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :       \
                        x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :         \
                        x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :     \
                        x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" : \
                        x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :     
\
+                       x == OCXL_IOCTL_GET_PLATFORM ? "GET_PLATFORM" : \
                        "UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
                break;
 #endif
 
+       case OCXL_IOCTL_GET_PLATFORM:
+               rc = afu_ioctl_get_platform(ctx,
+                               (struct ocxl_ioctl_platform __user *) args);
+               break;
+
        default:
                rc = -EINVAL;
        }
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..7bdd3efcf294 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
        __u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_PLATFORM_FLAGS0_P9_WAIT     0x01
+struct ocxl_ioctl_platform {
+       __u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD  _IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct 
ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT      _IOR(OCXL_MAGIC, 0x15, struct 
ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_PLATFORM _IOR(OCXL_MAGIC, 0x16, struct 
ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3