On Wed, 23 Aug 2023 11:21:58 +0200
Klaus Jensen wrote:
> From: Klaus Jensen
>
> Add i2c_smbus_pec() to calculate the SMBus Packet Error Code for a
> message.
>
> Signed-off-by: Klaus Jensen
Reviewed-by: Jonathan Cameron
> ---
> 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);
>
