From: Klaus Jensen <k.jen...@samsung.com>
Add i2c_smbus_pec() to calculate the SMBus Packet Error Code for a
message.
Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
Signed-off-by: Klaus Jensen <k.jen...@samsung.com>
---
hw/i2c/smbus_master.c | 26 ++++++++++++++++++++++++++
include/hw/i2c/smbus_master.h | 2 ++
2 files changed, 28 insertions(+)
diff --git a/hw/i2c/smbus_master.c b/hw/i2c/smbus_master.c
index 6a53c34e70b7..01a8e4700222 100644
--- a/hw/i2c/smbus_master.c
+++ b/hw/i2c/smbus_master.c
@@ -15,6 +15,32 @@
#include "hw/i2c/i2c.h"
#include "hw/i2c/smbus_master.h"
+static uint8_t crc8(uint16_t data)
+{
+ int i;
+
+ for (i = 0; i < 8; i++) {
+ if (data & 0x8000) {
+ data ^= 0x1070U << 3;
+ }
+
+ data <<= 1;
+ }
+
+ return (uint8_t)(data >> 8);
+}
+
+uint8_t i2c_smbus_pec(uint8_t crc, uint8_t *buf, size_t len)
+{
+ int i;
+
+ for (i = 0; i < len; i++) {
+ crc = crc8((crc ^ buf[i]) << 8);
+ }
+
+ return crc;
+}
+
/* Master device commands. */
int smbus_quick_command(I2CBus *bus, uint8_t addr, int read)
{
diff --git a/include/hw/i2c/smbus_master.h b/include/hw/i2c/smbus_master.h
index bb13bc423c22..d90f81767d86 100644
--- a/include/hw/i2c/smbus_master.h
+++ b/include/hw/i2c/smbus_master.h
@@ -27,6 +27,8 @@
#include "hw/i2c/i2c.h"
+uint8_t i2c_smbus_pec(uint8_t crc, uint8_t *buf, size_t len);
+
/* Master device commands. */
int smbus_quick_command(I2CBus *bus, uint8_t addr, int read);
int smbus_receive_byte(I2CBus *bus, uint8_t addr);
--
2.42.0
