[PATCH v2] ufs: core: print capabilities in controller's sysfs node

[Daniil Lunev]

Allows userspace to check supported by the controller/device
functionality, e.g. write booster.

Signed-off-by: Daniil Lunev <dlunev@xxxxxxxxxxxx>

---

Changes in v2:
* Add documentation entry for the new sysfs node.

 Documentation/ABI/testing/sysfs-driver-ufs |  9 +++++++++
 drivers/ufs/core/ufs-sysfs.c               | 10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
index 6b248abb1bd71..97e42e4763eaf 100644
--- a/Documentation/ABI/testing/sysfs-driver-ufs
+++ b/Documentation/ABI/testing/sysfs-driver-ufs
@@ -1591,6 +1591,15 @@ Description:	This entry shows the status of HPB.
 
 		The file is read only.
 
+What:		/sys/bus/platform/drivers/ufshcd/*/caps
+What:		/sys/bus/platform/devices/*.ufs/caps
+Date:		July 2022
+Contact:	Daniil Lunev <dlunev@xxxxxxxxxxxx>
+Description:	Read-only attribute. Enabled capabilities of the UFS driver. The
+		enabled capabilities are determined by what is supported by the
+		host controller and the UFS device.
+		Format: 0x%08llx
+
 What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/activation_thld
 Date:		February 2021
 Contact:	Avri Altman <avri.altman@xxxxxxx>
diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
index 0a088b47d5570..b0c294c367519 100644
--- a/drivers/ufs/core/ufs-sysfs.c
+++ b/drivers/ufs/core/ufs-sysfs.c
@@ -254,6 +254,14 @@ static ssize_t wb_on_store(struct device *dev, struct device_attribute *attr,
 	return res < 0 ? res : count;
 }
 
+static ssize_t caps_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "0x%08llx\n", hba->caps);
+}
+
 static DEVICE_ATTR_RW(rpm_lvl);
 static DEVICE_ATTR_RO(rpm_target_dev_state);
 static DEVICE_ATTR_RO(rpm_target_link_state);
@@ -262,6 +270,7 @@ static DEVICE_ATTR_RO(spm_target_dev_state);
 static DEVICE_ATTR_RO(spm_target_link_state);
 static DEVICE_ATTR_RW(auto_hibern8);
 static DEVICE_ATTR_RW(wb_on);
+static DEVICE_ATTR_RO(caps);
 
 static struct attribute *ufs_sysfs_ufshcd_attrs[] = {
 	&dev_attr_rpm_lvl.attr,
@@ -272,6 +281,7 @@ static struct attribute *ufs_sysfs_ufshcd_attrs[] = {
 	&dev_attr_spm_target_link_state.attr,
 	&dev_attr_auto_hibern8.attr,
 	&dev_attr_wb_on.attr,
+	&dev_attr_caps.attr,
 	NULL
 };
 
-- 
2.31.0