units: Add SI metric prefix definitions

stable inclusion
from stable-v5.10.166
commit 8ebc2efcb6d6731c12a3c3b18f9c2d17b651e888
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7TH9O

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8ebc2efcb6d6731c12a3c3b18f9c2d17b651e888

--------------------------------

[ Upstream commit 26471d4a ]

Sometimes it's useful to have well-defined SI metric prefix to be used
to self-describe the formulas or equations.

List most popular ones in the units.h.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NWolfram Sang <wsa@kernel.org>
Stable-dep-of: c8c37bc5 ("i2c: designware: use casting of u64 in clock multiplication to avoid overflow")
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

include/linux/units.h

@@ -4,6 +4,22 @@
 
 #include <linux/kernel.h>
 
+/* Metric prefixes in accordance with Système international (d'unités) */
+#define PETA	1000000000000000ULL
+#define TERA	1000000000000ULL
+#define GIGA	1000000000UL
+#define MEGA	1000000UL
+#define KILO	1000UL
+#define HECTO	100UL
+#define DECA	10UL
+#define DECI	10UL
+#define CENTI	100UL
+#define MILLI	1000UL
+#define MICRO	1000000UL
+#define NANO	1000000000UL
+#define PICO	1000000000000ULL
+#define FEMTO	1000000000000000ULL
+
 #define MILLIWATT_PER_WATT	1000L
 #define MICROWATT_PER_MILLIWATT	1000L
 #define MICROWATT_PER_WATT	1000000L