1 files changed, 293 insertions, 0 deletions
diff --git a/meta-openbmc-mods/meta-common/recipes-core/interfaces/libmctp/smbus.c b/meta-openbmc-mods/meta-common/recipes-core/interfaces/libmctp/smbus.c
new file mode 100644
index 000000000..8679a5185
--- /dev/null
+++ b/meta-openbmc-mods/meta-common/recipes-core/interfaces/libmctp/smbus.c
@@ -0,0 +1,293 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifdef MCTP_FILEIO
+#include <fcntl.h>
+#endif
+
+#define pr_fmt(x) "smbus: " x
+
+#include <i2c/smbus.h>
+#include <linux/i2c-dev.h>
+#include <linux/i2c.h>
+#include <sys/ioctl.h>
+
+#include "libmctp-alloc.h"
+#include "libmctp-log.h"
+#include "libmctp-smbus.h"
+#include "libmctp.h"
+
+struct mctp_binding_smbus {
+	struct mctp_binding binding;
+	struct mctp *mctp;
+	int out_fd;
+	int in_fd;
+
+	unsigned long bus_id;
+
+	/* receive buffer */
+	uint8_t rxbuf[1024];
+	struct mctp_pktbuf *rx_pkt;
+
+	/* temporary transmit buffer */
+	uint8_t txbuf[256];
+};
+
+#ifndef container_of
+#define container_of(ptr, type, member)                                        \
+	(type *)((char *)(ptr) - (char *)&((type *)0)->member)
+#endif
+
+#define binding_to_smbus(b) container_of(b, struct mctp_binding_smbus, binding)
+
+#define MCTP_COMMAND_CODE 0x0F
+#define MCTP_SLAVE_ADDRESS 0x1d
+#define MCTP_SOURCE_SLAVE_ADDRESS 0x21
+
+#define SMBUS_PEC_BYTE_SIZE 1
+
+struct mctp_smbus_header_tx {
+	uint8_t source_slave_address;
+};
+
+struct mctp_smbus_header_rx {
+	uint8_t destination_slave_address;
+	uint8_t command_code;
+	uint8_t byte_count;
+	uint8_t source_slave_address;
+};
+
+static int mctp_binding_smbus_tx(struct mctp_binding *b,
+				 struct mctp_pktbuf *pkt)
+{
+	struct mctp_binding_smbus *smbus = binding_to_smbus(b);
+	struct mctp_smbus_header_tx *hdr;
+	uint8_t *buf;
+	size_t len;
+	int r;
+	struct i2c_msg msg;
+	struct i2c_rdwr_ioctl_data data;
+
+	data.msgs = &msg;
+	data.nmsgs = 1;
+
+	uint16_t timeout = 1000;
+	int i;
+
+	/* the length field in the header excludes smbus framing
+	 * and escape sequences */
+	len = mctp_pktbuf_size(pkt);
+
+	hdr = (void *)smbus->txbuf;
+
+	// hdr->len = len + 1;  // +1 for PET byte
+	hdr->source_slave_address = MCTP_SOURCE_SLAVE_ADDRESS;
+
+	buf = (void *)(hdr + sizeof(*hdr));
+
+	if (len + sizeof(*hdr) > sizeof(smbus->txbuf))
+		return -1;
+
+	memcpy(buf, &pkt->data[pkt->start], len);
+
+	buf += len;
+
+	if (ioctl(smbus->out_fd, I2C_SLAVE, MCTP_SLAVE_ADDRESS) < 0) {
+		mctp_prerr("Can't set slave");
+		return -1;
+	}
+	if (ioctl(smbus->out_fd, I2C_PEC, 1) < 0) {
+		mctp_prerr("Cant set PEC byte");
+		return -1;
+	}
+
+	if (i2c_smbus_write_block_data(smbus->out_fd, MCTP_COMMAND_CODE,
+				       sizeof(*hdr) + len, (void *)smbus->txbuf)
+	    < 0) {
+		mctp_prerr("Failed to send");
+		return -1;
+	}
+
+	return 0;
+}
+
+#ifdef MCTP_FILEIO
+int mctp_smbus_read(struct mctp_binding_smbus *smbus)
+{
+	ssize_t len;
+	int r;
+	struct mctp_smbus_header_rx *hdr;
+
+	r = lseek(smbus->in_fd, 0, SEEK_SET);
+	if (r < 0) {
+		mctp_prerr("Failed to seek");
+		return -1;
+	}
+	len = read(smbus->in_fd, smbus->rxbuf, sizeof(smbus->rxbuf));
+	if (len < sizeof(*hdr)) {
+		// TODO Don't return an error here, as it seems to happen from
+		// time to time, even with a properly written poll loop,
+		// although it's not clear why.
+		return 0;
+	}
+
+	hdr = (void *)smbus->rxbuf;
+	if (hdr->destination_slave_address
+	    != (MCTP_SOURCE_SLAVE_ADDRESS & ~1)) {
+		mctp_prerr("Got bad slave address %d",
+			   hdr->destination_slave_address);
+		return 0;
+	}
+	if (hdr->command_code != MCTP_COMMAND_CODE) {
+		mctp_prerr("Got bad command code %d", hdr->command_code);
+		// Not a payload intended for us
+		return 0;
+	}
+
+	if (hdr->byte_count != (len - sizeof(*hdr))) {
+		// Got an incorrectly sized payload
+		mctp_prerr("Got smbus payload sized %d, expecting %d",
+			   hdr->byte_count, len - sizeof(*hdr));
+		return 0;
+	}
+
+	if (len < 0) {
+		mctp_prerr("can't read from smbus device: %m");
+		return -1;
+	}
+
+	smbus->rx_pkt = mctp_pktbuf_alloc(0);
+	assert(smbus->rx_pkt);
+
+	if (mctp_pktbuf_push(smbus->rx_pkt, &smbus->rxbuf[sizeof(*hdr)],
+			     len - sizeof(*hdr) - SMBUS_PEC_BYTE_SIZE)
+	    != 0) {
+		mctp_prerr("Can't push tok pktbuf: %m");
+		return -1;
+	}
+
+	mctp_bus_rx(&(smbus->binding), smbus->rx_pkt);
+
+	mctp_pktbuf_free(smbus->rx_pkt);
+	smbus->rx_pkt = NULL;
+
+	return 0;
+}
+
+int mctp_smbus_get_in_fd(struct mctp_binding_smbus *smbus)
+{
+	return smbus->in_fd;
+}
+
+int mctp_smbus_get_out_fd(struct mctp_binding_smbus *smbus)
+{
+	return smbus->out_fd;
+}
+
+int mctp_smbus_open_bus(struct mctp_binding_smbus *smbus, int out_bus_num,
+			int root_bus_num)
+{
+	char filename[60];
+	size_t filename_size;
+	char slave_mqueue[20];
+	size_t mqueue_size;
+
+	int fd;
+
+	size_t size;
+	int address_7_bit;
+
+	address_7_bit = MCTP_SOURCE_SLAVE_ADDRESS >> 1;
+	size = sizeof(filename);
+	snprintf(filename, size,
+		 "/sys/bus/i2c/devices/i2c-%d/%d-%04x/slave-mqueue",
+		 root_bus_num, root_bus_num,
+		 (address_7_bit << 8) + address_7_bit);
+
+	smbus->in_fd = open(filename, O_RDONLY | O_NONBLOCK | O_CLOEXEC);
+	if (smbus->in_fd < 0) {
+		// Device doesn't exist.  Create it.
+		filename_size = sizeof(filename);
+		snprintf(filename, filename_size,
+			 "/sys/bus/i2c/devices/i2c-%d/new_device",
+			 root_bus_num);
+		filename[filename_size - 1] = '\0';
+
+		fd = open(filename, O_WRONLY);
+		if (fd < 0) {
+			mctp_prerr("can't open root device %s: %m", filename);
+			return -1;
+		}
+
+		mqueue_size = sizeof(slave_mqueue);
+		snprintf(slave_mqueue, mqueue_size, "slave-mqueue %#04x",
+			 (address_7_bit << 8) + address_7_bit);
+
+		size = write(fd, slave_mqueue, mqueue_size);
+		close(fd);
+		if (size != mqueue_size) {
+			mctp_prerr("can't create mqueue device on %s: %m",
+				   filename);
+			return -1;
+		}
+
+		size = sizeof(filename);
+		snprintf(filename, size,
+			 "/sys/bus/i2c/devices/i2c-%d/%d-%04x/slave-mqueue",
+			 root_bus_num, root_bus_num,
+			 (address_7_bit << 8) + address_7_bit);
+
+		smbus->in_fd =
+			open(filename, O_RDONLY | O_NONBLOCK | O_CLOEXEC);
+		if (smbus->in_fd < 0) {
+			mctp_prerr("can't open mqueue device on %s: %m",
+				   filename);
+			return -2;
+		}
+	}
+
+	size = sizeof(filename);
+	snprintf(filename, size, "/dev/i2c-%d", out_bus_num);
+	filename[size - 1] = '\0';
+
+	smbus->out_fd = open(filename, O_RDWR | O_NONBLOCK);
+	if (smbus->out_fd < 0) {
+		close(smbus->in_fd);
+		mctp_prerr("can't open device %s: %m", filename);
+	}
+
+	return 0;
+}
+
+#endif
+
+void mctp_smbus_register_bus(struct mctp_binding_smbus *smbus,
+			     struct mctp *mctp, mctp_eid_t eid)
+{
+	assert(smbus->out_fd >= 0);
+	assert(smbus->in_fd >= 0);
+	smbus->mctp = mctp;
+	smbus->bus_id = mctp_register_bus(mctp, &smbus->binding, eid);
+}
+
+struct mctp_binding_smbus *mctp_smbus_init(void)
+{
+	struct mctp_binding_smbus *smbus;
+
+	smbus = __mctp_alloc(sizeof(*smbus));
+	smbus->in_fd = -1;
+	smbus->out_fd = -1;
+
+	smbus->rx_pkt = NULL;
+	smbus->binding.name = "smbus";
+	smbus->binding.version = 1;
+
+	smbus->binding.tx = mctp_binding_smbus_tx;
+
+	return smbus;
+}