[PATCH v3 9/9] Documentation: ABI: Add sysfs ABI documentation for DDR training data

[Kishore Batta <kishore.batta@oss.qualcomm.com>]

Add ABI documentation for the DDR training data sysfs attribute exposed by
the sahara MHI driver.

The documented sysfs node provides read-only access to the DDR training
data captured during sahara command mode and exposed via the MHI
controller device. This allows userspace to read the training data and
manage it as needed outside the kernel.

Signed-off-by: Kishore Batta <kishore.batta@oss.qualcomm.com>
---
 .../ABI/testing/sysfs-bus-mhi-ddr_training_data       | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data b/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data
new file mode 100644
index 0000000000000000000000000000000000000000..810b487b5a5fdba133d81255f9879844e3938a10
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data
@@ -0,0 +1,19 @@
+What:                   /sys/bus/mhi/devices/<mhi-cntrl>/ddr_training_data
+
+Date:                   March 2026
+
+Contact:                Kishore Batta <kishore.batta@oss.qualcomm.com>
+
+Description:            Contains the DDR training data for the Qualcomm device
+                        connected. MHI driver populates different controller
+                        nodes for each device. The DDR training data is exposed
+                        to userspace to read and save the training data file to
+                        the filesystem. In the subsequent boot up of the device,
+                        the training data is restored from host to device
+                        optimizing the boot up time of the device.
+
+Usage:                  Example for reading DDR training data:
+                        cat /sys/bus/mhi/devices/mhi0/ddr_training_data
+
+Permissions:            The file permissions are set to 0444 allowing read
+                        access.

-- 
2.34.1