dm: mei: add sysfs read functions

mei requires reading of u8, u32 and uuid
sysfs files.

Tracked-On: #1536
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Vitaly Lubart <vitaly.lubart@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>

Author: Tomas Winkler

devicemodel/hw/pci/virtio/virtio_mei.c

@@ -41,6 +41,12 @@
 
 #include "mei.h"
 
+#ifndef BIT
+#define BIT(x) (1 << (x))
+#endif
+
+#define DEV_NAME_SIZE sizeof(((struct dirent *)0)->d_name)
+
 #ifndef UUID_STR_LEN
 #define UUID_STR_LEN 37
 #endif
@@ -146,3 +152,72 @@ refcnt_put(const struct refcnt *ref)
 	if (__sync_sub_and_fetch((int *)&ref->count, 1) == 0)
 		ref->destroy(ref);
 }
+
+static int mei_sysfs_read_property_file(const char *fname, char *buf, size_t sz)
+{
+	int fd;
+	int rc;
+
+	if (!buf)
+		return -EINVAL;
+
+	if (!sz)
+		return 0;
+
+	fd = open(fname, O_RDONLY);
+	if (fd < 0) {
+		DPRINTF("open failed %s %d\n", fname, errno);
+		return -1;
+	}
+
+	rc = read(fd, buf, sz);
+
+	close(fd);
+
+	return rc;
+}
+
+static int mei_sysfs_read_property_u8(const char *fname, uint8_t *u8_property)
+{
+	char buf[4] = {0};
+	unsigned long int res;
+
+	if (mei_sysfs_read_property_file(fname, buf, sizeof(buf) - 1) < 0)
+		return -1;
+
+	res = strtoul(buf, NULL, 10);
+	if (res >= 256)
+		return -1;
+
+	*u8_property = (uint8_t)res;
+
+	return 0;
+}
+
+static int mei_sysfs_read_property_u32(const char *fname,
+				       uint32_t *u32_property)
+{
+	char buf[32] = {0};
+	unsigned long int res;
+
+	if (mei_sysfs_read_property_file(fname, buf, sizeof(buf) - 1) < 0)
+		return -1;
+
+	res = strtoul(buf, NULL, 10);
+	if (res == ULONG_MAX)
+		return -1;
+
+	*u32_property = res;
+
+	return 0;
+}
+
+static int mei_sysfs_read_property_uuid(char *fname, guid_t *uuid)
+{
+	char buf[UUID_STR_LEN] = {0};
+
+	if (mei_sysfs_read_property_file(fname, buf, sizeof(buf) - 1) < 0)
+		return -1;
+
+	return guid_parse(buf, sizeof(buf), uuid);
+}