ASoC: Intel: avs: Expose FW version with sysfs

Add functionality to read version of loaded FW from sysfs.

Signed-off-by: Cezary Rojewski <[e-mail]>
Signed-off-by: Amadeusz Sławiński <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/ABI/testing/sysfs-bus-pci-devices-avs

···
+What:		/sys/devices/pci0000:00/<dev>/avs/fw_version
+Date:		February 2024
+Contact:	Cezary Rojewski <[e-mail]>
+Description:
+		Version of AudioDSP firmware ASoC avs driver is communicating
+		with.
+
+		Format: %d.%d.%d.%d, type:major:minor:build.

sound/soc/intel/avs/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
 
 snd-soc-avs-objs := dsp.o ipc.o messages.o utils.o core.o loader.o \
-		    topology.o path.o pcm.o board_selection.o control.o
+		    topology.o path.o pcm.o board_selection.o control.o \
+		    sysfs.o
 snd-soc-avs-objs += cldma.o
 snd-soc-avs-objs += skl.o apl.o
 

sound/soc/intel/avs/avs.h

···
 static inline void avs_debugfs_exit(struct avs_dev *adev) { }
 #endif
 
+/* Filesystems integration */
+
+extern const struct attribute_group *avs_attr_groups[];
+
 #endif /* __SOUND_SOC_INTEL_AVS_H */

sound/soc/intel/avs/core.c

···
 	.probe = avs_pci_probe,
 	.remove = avs_pci_remove,
 	.shutdown = avs_pci_shutdown,
+	.dev_groups = avs_attr_groups,
 	.driver = {
 		.pm = &avs_dev_pm,
 	},

sound/soc/intel/avs/sysfs.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright(c) 2021-2024 Intel Corporation. All rights reserved.
+//
+// Authors: Cezary Rojewski <[e-mail]>
+//          Amadeusz Slawinski <[e-mail]>
+//
+
+#include <linux/sysfs.h>
+#include "avs.h"
+
+static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct avs_dev *adev = to_avs_dev(dev);
+	struct avs_fw_version *fw_version = &adev->fw_cfg.fw_version;
+
+	return sysfs_emit(buf, "%d.%d.%d.%d\n", fw_version->major, fw_version->minor,
+			  fw_version->hotfix, fw_version->build);
+}
+static DEVICE_ATTR_RO(fw_version);
+
+static struct attribute *avs_fw_attrs[] = {
+	&dev_attr_fw_version.attr,
+	NULL
+};
+
+static const struct attribute_group avs_attr_group = {
+	.name = "avs",
+	.attrs = avs_fw_attrs,
+};
+
+const struct attribute_group *avs_attr_groups[] = {
+	&avs_attr_group,
+	NULL
+};