[PATCH 2/4] cdx: add sysfs for reset_all

[Abhijit Gangurde <abhijit.gangurde@amd.com>]

Add sysfs for reset_all entry which resets all the
devices on the CDX bus.

Co-developed-by: Puneet Gupta <puneet.gupta@amd.com>
Signed-off-by: Puneet Gupta <puneet.gupta@amd.com>
Co-developed-by: Nipun Gupta <nipun.gupta@amd.com>
Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Tested-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
---
 Documentation/ABI/testing/sysfs-bus-cdx | 11 ++++++++++
 drivers/cdx/cdx.c                       | 29 +++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-cdx b/Documentation/ABI/testing/sysfs-bus-cdx
index 0afa85b3c63b..d9e00058471d 100644
--- a/Documentation/ABI/testing/sysfs-bus-cdx
+++ b/Documentation/ABI/testing/sysfs-bus-cdx
@@ -22,6 +22,17 @@ Description:
 
 		  # echo 0 > /sys/bus/cdx/enable
 
+What:		/sys/bus/cdx/reset_all
+Date:		July 2023
+Contact:	puneet.gupta@amd.com
+Description:
+		Writing y/1/on to this file resets all the devices
+		present on the CDX bus
+
+		For example::
+
+		  # echo 1 > /sys/bus/cdx/reset_all
+
 What:		/sys/bus/cdx/devices/.../vendor
 Date:		March 2023
 Contact:	nipun.gupta@amd.com
diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index 48c493a43491..4d20047b55bb 100644
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c
@@ -106,6 +106,11 @@ int cdx_dev_reset(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(cdx_dev_reset);
 
+static int reset_cdx_device(struct device *dev, void *data)
+{
+	return cdx_dev_reset(dev);
+}
+
 /**
  * cdx_unregister_device - Unregister a CDX device
  * @dev: CDX device
@@ -433,9 +438,33 @@ static ssize_t rescan_store(const struct bus_type *bus,
 }
 static BUS_ATTR_WO(rescan);
 
+static ssize_t reset_all_store(const struct bus_type *bus,
+			       const char *buf, size_t count)
+{
+	bool val;
+	int ret;
+
+	if (kstrtobool(buf, &val) < 0)
+		return -EINVAL;
+
+	if (!val)
+		return -EINVAL;
+
+	/* Reset all the devices attached to cdx bus */
+	ret = bus_for_each_dev(bus, NULL, NULL, reset_cdx_device);
+	if (ret) {
+		pr_err("error in CDX bus reset\n");
+		return 0;
+	}
+
+	return count;
+}
+static BUS_ATTR_WO(reset_all);
+
 static struct attribute *cdx_bus_attrs[] = {
 	&bus_attr_enable.attr,
 	&bus_attr_rescan.attr,
+	&bus_attr_reset_all.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(cdx_bus);
-- 
2.25.1