accel/habanalabs: add parent_device sysfs attribute

The device debugfs directory was modified to be named as the
device-name.
This name is the parent device name, i.e. either the PCI address in case
of an ASIC, or the simulator device name in case of a simulator.

This change makes it more difficult for a user to access the debugfs
directory for a specific accel device, because he can't just use the
accel minor id, but he needs to do more device-dependent operations to
get the device name.

To make it easier to get this name, add a 'parent_device' sysfs
attribute that the user can read using the minor id before accessing
debugfs.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

Author: Tomer Tayar

Documentation/ABI/testing/sysfs-driver-habanalabs

@@ -155,6 +155,12 @@ KernelVersion:  not yet upstreamed
 Contact:        ogabbay@kernel.org
 Description:    Displays the device's module id
 
+What:           /sys/class/accel/accel<n>/device/parent_device
+Date:           Nov 2023
+KernelVersion:  6.8
+Contact:        ttayar@habana.ai
+Description:    Displays the name of the parent device of the accel device
+
 What:           /sys/class/accel/accel<n>/device/pci_addr
 Date:           Jan 2019
 KernelVersion:  5.1

drivers/accel/habanalabs/common/habanalabs.h

@@ -3521,6 +3521,9 @@ struct hl_device {
 	u8				heartbeat;
 };
 
+/* Retrieve PCI device name in case of a PCI device or dev name in simulator */
+#define HL_DEV_NAME(hdev)	\
+		((hdev)->pdev ? dev_name(&(hdev)->pdev->dev) : "NA-DEVICE")
 
 /**
  * struct hl_cs_encaps_sig_handle - encapsulated signals handle structure

drivers/accel/habanalabs/common/sysfs.c

@@ -410,6 +410,13 @@ static ssize_t module_id_show(struct device *dev,
 	return sprintf(buf, "%u\n", le32_to_cpu(hdev->asic_prop.cpucp_info.card_location));
 }
 
+static ssize_t parent_device_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct hl_device *hdev = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", HL_DEV_NAME(hdev));
+}
+
 static DEVICE_ATTR_RO(armcp_kernel_ver);
 static DEVICE_ATTR_RO(armcp_ver);
 static DEVICE_ATTR_RO(cpld_ver);
@@ -430,6 +437,7 @@ static DEVICE_ATTR_RO(uboot_ver);
 static DEVICE_ATTR_RO(fw_os_ver);
 static DEVICE_ATTR_RO(security_enabled);
 static DEVICE_ATTR_RO(module_id);
+static DEVICE_ATTR_RO(parent_device);
 
 static struct bin_attribute bin_attr_eeprom = {
 	.attr = {.name = "eeprom", .mode = (0444)},
@@ -456,6 +464,7 @@ static struct attribute *hl_dev_attrs[] = {
 	&dev_attr_fw_os_ver.attr,
 	&dev_attr_security_enabled.attr,
 	&dev_attr_module_id.attr,
+	&dev_attr_parent_device.attr,
 	NULL,
 };