| Message ID | 20230531114744.9946-2-its@irrelevant.dk |
|---|---|
| State | New |
| Headers | show |
| Series | hw/{i2c, nvme}: mctp endpoint, nvme management interface model | expand |
On 31/5/23 13:47, Klaus Jensen wrote: > From: Klaus Jensen <k.jensen@samsung.com> > > Add i2c_smbus_pec() to calculate the SMBus Packet Error Code for a > message. > > Signed-off-by: Klaus Jensen <k.jensen@samsung.com> > --- > hw/i2c/smbus_master.c | 28 ++++++++++++++++++++++++++++ > include/hw/i2c/smbus_master.h | 2 ++ > 2 files changed, 30 insertions(+) > > diff --git a/hw/i2c/smbus_master.c b/hw/i2c/smbus_master.c > index 6a53c34e70b7..47f9eb24e033 100644 > --- a/hw/i2c/smbus_master.c > +++ b/hw/i2c/smbus_master.c > @@ -15,6 +15,34 @@ > #include "hw/i2c/i2c.h" > #include "hw/i2c/smbus_master.h" > > +static uint8_t crc8(uint16_t data) > +{ > +#define POLY (0x1070U << 3) static const unsigned crc8_poly = ..., but why not inline the single use? data ^= 0x1070U << 3; and data <<= 1; > + int i; > + > + for (i = 0; i < 8; i++) { > + if (data & 0x8000) { > + data = data ^ POLY; > + } > + > + data = data << 1; > + } > + > + return (uint8_t)(data >> 8); > +#undef POLY > +} We have "qemu/crc32c.h", maybe we could have a similar crc8.h. Just wondering...
diff --git a/hw/i2c/smbus_master.c b/hw/i2c/smbus_master.c index 6a53c34e70b7..47f9eb24e033 100644 --- a/hw/i2c/smbus_master.c +++ b/hw/i2c/smbus_master.c @@ -15,6 +15,34 @@ #include "hw/i2c/i2c.h" #include "hw/i2c/smbus_master.h" +static uint8_t crc8(uint16_t data) +{ +#define POLY (0x1070U << 3) + int i; + + for (i = 0; i < 8; i++) { + if (data & 0x8000) { + data = data ^ POLY; + } + + data = data << 1; + } + + return (uint8_t)(data >> 8); +#undef POLY +} + +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);