On Wed, 23 Aug 2023 11:21:59 +0200 Klaus Jensen <i...@irrelevant.dk> wrote:
> From: Klaus Jensen <k.jen...@samsung.com> > > Add an abstract MCTP over I2C endpoint model. This implements MCTP > control message handling as well as handling the actual I2C transport > (packetization). > > Devices are intended to derive from this and implement the class > methods. > > Parts of this implementation is inspired by code[1] previously posted by > Jonathan Cameron. > > Squashed a fix[2] from Matt Johnston. > > [1]: > https://lore.kernel.org/qemu-devel/20220520170128.4436-1-jonathan.came...@huawei.com/ > [2]: > https://lore.kernel.org/qemu-devel/20221121080445.ga29...@codeconstruct.com.au/ > > Signed-off-by: Klaus Jensen <k.jen...@samsung.com> I made the minor changes to the CXL FM-API PoC to use this and all works as expected so Tested-by: Jonathan Cameron <jonathan.came...@huawei.com> Some minor things inline. With those tidied up or ignored with clear reasoning. Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com> > diff --git a/hw/i2c/mctp.c b/hw/i2c/mctp.c > new file mode 100644 > index 000000000000..217073d62435 > --- /dev/null > +++ b/hw/i2c/mctp.c ... > +static int i2c_mctp_event_cb(I2CSlave *i2c, enum i2c_event event) > +{ > + MCTPI2CEndpoint *mctp = MCTP_I2C_ENDPOINT(i2c); > + MCTPI2CEndpointClass *mc = MCTP_I2C_ENDPOINT_GET_CLASS(mctp); > + MCTPI2CPacket *pkt = (MCTPI2CPacket *)mctp->buffer; > + size_t payload_len; > + uint8_t pec, pktseq, msgtype; > + > + switch (event) { > + case I2C_START_SEND: > + if (mctp->state == I2C_MCTP_STATE_IDLE) { > + mctp->state = I2C_MCTP_STATE_RX_STARTED; > + } else if (mctp->state != I2C_MCTP_STATE_RX) { > + return -1; > + } > + > + /* the i2c core eats the slave address, so put it back in */ > + pkt->i2c.dest = i2c->address << 1; > + mctp->len = 1; > + > + return 0; > + > + case I2C_FINISH: > + if (mctp->len < sizeof(MCTPI2CPacket) + 1) { > + trace_i2c_mctp_drop_short_packet(mctp->len); > + goto drop; > + } > + > + payload_len = mctp->len - (1 + offsetof(MCTPI2CPacket, > mctp.payload)); > + > + if (pkt->i2c.byte_count + 3 != mctp->len - 1) { > + trace_i2c_mctp_drop_invalid_length(pkt->i2c.byte_count + 3, > + mctp->len - 1); > + goto drop; > + } > + > + pec = i2c_smbus_pec(0, mctp->buffer, mctp->len - 1); > + if (mctp->buffer[mctp->len - 1] != pec) { > + trace_i2c_mctp_drop_invalid_pec(mctp->buffer[mctp->len - 1], > pec); > + goto drop; > + } > + > + if (!(pkt->mctp.hdr.eid.dest == mctp->my_eid || > + pkt->mctp.hdr.eid.dest == 0)) { > + trace_i2c_mctp_drop_invalid_eid(pkt->mctp.hdr.eid.dest, > + mctp->my_eid); > + goto drop; > + } > + > + pktseq = FIELD_EX8(pkt->mctp.hdr.flags, MCTP_H_FLAGS, PKTSEQ); > + > + if (FIELD_EX8(pkt->mctp.hdr.flags, MCTP_H_FLAGS, SOM)) { > + mctp->tx.is_control = false; > + > + if (mctp->state == I2C_MCTP_STATE_RX) { > + mc->reset(mctp); > + } > + > + mctp->state = I2C_MCTP_STATE_RX; > + > + mctp->tx.addr = pkt->i2c.source >> 1; > + mctp->tx.eid = pkt->mctp.hdr.eid.source; > + mctp->tx.tag = FIELD_EX8(pkt->mctp.hdr.flags, MCTP_H_FLAGS, TAG); > + mctp->tx.pktseq = pktseq; > + > + msgtype = FIELD_EX8(pkt->mctp.payload[0], MCTP_MESSAGE_H, TYPE); > + > + if (msgtype == MCTP_MESSAGE_TYPE_CONTROL) { > + mctp->tx.is_control = true; > + > + i2c_mctp_handle_control(mctp); > + > + return 0; > + } > + } else if (mctp->state == I2C_MCTP_STATE_RX_STARTED) { > + trace_i2c_mctp_drop_expected_som(); > + goto drop; > + } else if (pktseq != (++mctp->tx.pktseq & 0x3)) { > + trace_i2c_mctp_drop_invalid_pktseq(pktseq, mctp->tx.pktseq & > 0x3); > + goto drop; > + } > + > + mc->put_buf(mctp, i2c_mctp_payload(mctp->buffer), payload_len); Given this returns -1 on error should probably handle errors. > + > + if (FIELD_EX8(pkt->mctp.hdr.flags, MCTP_H_FLAGS, EOM)) { > + mc->handle(mctp); > + mctp->state = I2C_MCTP_STATE_WAIT_TX; > + } > + > + return 0; > + > + default: > + return -1; > + } > + > +drop: > + mc->reset(mctp); > + > + mctp->state = I2C_MCTP_STATE_IDLE; > + > + return 0; > +} ... > diff --git a/include/hw/i2c/mctp.h b/include/hw/i2c/mctp.h > new file mode 100644 > index 000000000000..fccbf249cdbe > --- /dev/null > +++ b/include/hw/i2c/mctp.h > @@ -0,0 +1,127 @@ > +#ifndef QEMU_I2C_MCTP_H > +#define QEMU_I2C_MCTP_H > + > +#include "qom/object.h" > +#include "hw/qdev-core.h" > + > +#define TYPE_MCTP_I2C_ENDPOINT "mctp-i2c-endpoint" > +OBJECT_DECLARE_TYPE(MCTPI2CEndpoint, MCTPI2CEndpointClass, MCTP_I2C_ENDPOINT) > + > +struct MCTPI2CEndpointClass { > + I2CSlaveClass parent_class; > + > + /** > + * Drop the blank line for consistency with the other comments. > + * put_buf() - receive incoming message fragment > + * > + * Must returns 0 for succes or -1 for error. I would expect any negative to count as error rather than just -1. Also, simple imperative should be clear enough * Return 0 for success or negative for error. > + */ > + int (*put_buf)(MCTPI2CEndpoint *mctp, uint8_t *buf, size_t len); > + > + /** > + * get_buf() - provide pointer to message fragment > + * > + * Called by the mctp subsystem to request a pointer to the next message > + * fragment. The implementation must advance its internal position such > + * that successive calls returns the next fragments. Subsequent call with return next fragment. Up to the implementation to decide how it does this. > + * > + * Must return the number of bytes available. Return number of bytes in message fragment. Available might mean in all fragments. > + */ > + size_t (*get_buf)(MCTPI2CEndpoint *mctp, const uint8_t **buf, > + size_t maxlen, uint8_t *mctp_flags); > + > + /** > + * handle() - handle an MCTP message > + * > + * Called by the mctp subsystem when a full message has been delivered > and > + * may be parsed and processed. > + */ > + void (*handle)(MCTPI2CEndpoint *mctp); > + > + /** > + * reset() - reset internal state > + * > + * Called by the mctp subsystem in the event of some transport error. > + * Implementation must reset its internal state and drop any fragments > + * previously receieved. > + */ > + void (*reset)(MCTPI2CEndpoint *mctp); > + > + /** > + * get_types() - provide supported mctp message types > + * > + * Must provide a buffer with a full MCTP supported message types payload > + * (i.e. `0x0(SUCCESS),0x1(COUNT),0x4(NMI)`). > + * > + * Returns the size of the response. > + */ > + size_t (*get_types)(MCTPI2CEndpoint *mctp, const uint8_t **data); > +}; > + > +/* > + * Maximum value of the SMBus Block Write "Byte Count" field (8 bits). > + * > + * This is the count of bytes that follow the Byte Count field and up to, but > + * not including, the PEC byte. > + */ > +#define I2C_MCTP_MAXBLOCK 255 > + > +/* > + * Maximum Transmission Unit under I2C. > + * > + * This is for the MCTP Packet Payload (255, subtracting the 4 byte MCTP > Packet > + * Header or the 1 byte MCTP/I2C piggy-backed source address). and the 1 byte.. ? > + */ > +#define I2C_MCTP_MAXMTU (I2C_MCTP_MAXBLOCK - (sizeof(MCTPPacketHeader) + 1)) > + > +/* > + * Maximum length of an MCTP/I2C packet. > + * > + * This is the sum of the three I2C header bytes (Destination target address, > + * Command Code and Byte Count), the maximum number of bytes in a message > (255) > + * and the 1 byte Packet Error Code. > + */ > +#define I2C_MCTP_MAX_LENGTH (3 + I2C_MCTP_MAXBLOCK + 1) > + > +typedef enum { > + I2C_MCTP_STATE_IDLE, > + I2C_MCTP_STATE_RX_STARTED, > + I2C_MCTP_STATE_RX, > + I2C_MCTP_STATE_WAIT_TX, > + I2C_MCTP_STATE_TX, > +} MCTPState; > + > +typedef enum { > + I2C_MCTP_STATE_TX_START_SEND, > + I2C_MCTP_STATE_TX_SEND_BYTE, > +} MCTPTxState; > + > +typedef struct MCTPI2CEndpoint { > + I2CSlave parent_obj; > + I2CBus *i2c; > + > + MCTPState state; > + > + /* mctp endpoint identifier */ > + uint8_t my_eid; > + > + uint8_t buffer[I2C_MCTP_MAX_LENGTH]; > + uint64_t pos; > + size_t len; > + > + struct { > + MCTPTxState state; > + bool is_control; > + > + uint8_t eid; > + uint8_t addr; > + uint8_t pktseq; > + uint8_t tag; > + > + QEMUBH *bh; > + } tx; > +} MCTPI2CEndpoint; > + > +void i2c_mctp_schedule_send(MCTPI2CEndpoint *mctp); > + > +#endif /* QEMU_I2C_MCTP_H */