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Add a new smbus_writeread command to perform a write followed by a read in one transaction. #20

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Add a new smbus_writeread command to perform a write followed by a read in one transaction. #20

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553f137
Add a new smbus_writeread command to perform a write followed by a
jmeurin Mar 30, 2017
aedc759
Changing the order of the arguments to be <write_bytes> <read_count>.
jmeurin Apr 6, 2017
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2 changes: 0 additions & 2 deletions linux-i2c-dev.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,6 @@ struct i2c_msg {
#define I2C_M_NO_RD_ACK 0x0800
short len; /* msg length */
char *buf; /* pointer to msg data */
int err;
short done;
};

/* To determine what functionality is present */
Expand Down
79 changes: 78 additions & 1 deletion smbus_rw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ enum SMBUS_SIZE
SMBUS_QUICK,
SMBUS_PROC_CALL,
SMBUS_BLOCK_PROC_CALL,
SMBUS_WRITE_READ,
};

typedef union {
Expand All @@ -56,6 +57,7 @@ struct smbus_op_params {
uint8_t reg;
uint8_t i2c_bus;
uint8_t address;
uint8_t read_count;
int len;
SMBUS_DTYPE data;
};
Expand Down Expand Up @@ -187,6 +189,7 @@ parse_io_width(const char *arg, struct smbus_op_params *params,
break;
case SMBUS_SIZE_BLOCK:
case SMBUS_BLOCK_PROC_CALL:
case SMBUS_WRITE_READ:
{
int len;
const char *src = arg;
Expand Down Expand Up @@ -281,7 +284,9 @@ smbus_prologue(const char *argv[], struct smbus_op_params *params,

/* Only obtain the register if size designates that it is not a byte
* or quick operation. */
if (op->size != SMBUS_SIZE_BYTE && op->size != SMBUS_QUICK) {
if (op->size != SMBUS_SIZE_BYTE &&
op->size != SMBUS_QUICK &&
op->size != SMBUS_WRITE_READ) {
if (parse_uint8(argv[3], &params->reg)) {
fprintf(stderr, "invalid register value\n");
return -1;
Expand Down Expand Up @@ -547,6 +552,73 @@ smbus_block_process_call_op(struct smbus_op_params *params,
return 0;
}

static int
smbus_writeread(int argc, const char *argv[], const struct cmd_info *info)
{
int ret;
struct smbus_op_params params;
memset(&params, 0, sizeof(params));
const struct smbus_op *op = (const struct smbus_op *)info->privdata;

if (smbus_prologue(argv, &params, op) < 0) {
return -1;
}

if (parse_io_width(argv[3], &params, op) < 0) {
fprintf(stderr, "%s: %s: invalid value to write\n",
argv[0], argv[3]);
close(params.fd);
return -1;
}
if(parse_uint8(argv[4], &params.read_count) < 0) {
fprintf(stderr, "invalid read count %s.\n", argv[4]);
return -1;
}
if (params.read_count > I2C_SMBUS_BLOCK_MAX) {
fprintf(stderr, "read count %s > %d.\n",
argv[3], I2C_SMBUS_BLOCK_MAX);
return -1;
}
ret = op->perform_op(&params, op);

close(params.fd);

return ret;
}

static int
smbus_writeread_op(struct smbus_op_params *params, const struct smbus_op *op)
{
struct i2c_msg msg[2];
struct i2c_rdwr_ioctl_data data;

/* First transfer: write the params bytes */
msg[0].addr = params->address;
msg[0].flags = 0;
msg[0].len = params->len;
msg[0].buf = (char*) params->data.array;

/* Second transfer: read `read_count` bytes */
msg[1].addr = params->address;
msg[1].flags = I2C_M_RD;
msg[1].len = params->read_count;
msg[1].buf = (char*) params->data.array;

/* Run the transfers */
data.msgs = msg;
data.nmsgs = 2;
int rv = ioctl(params->fd, I2C_RDWR, &data);

/* Error check */
if (rv < 0) {
fprintf(stderr, "I2C_RDWR failed: %s\n", strerror(errno));
return -1;
}

print_read_data(SMBUS_SIZE_BLOCK, params->read_count, &params->data);
return 0;
}

MAKE_PREREQ_PARAMS_FIXED_ARGS(smbus_read_params, 4,
"<adapter> <address> <register>", 0);
MAKE_PREREQ_PARAMS_FIXED_ARGS(smbus_write_params, 5,
Expand All @@ -557,6 +629,8 @@ MAKE_PREREQ_PARAMS_FIXED_ARGS(smbus_send_byte_params, 4,
"<adapter> <address> <value>", 0);
MAKE_PREREQ_PARAMS_FIXED_ARGS(smbus_quick_params, 4,
"<adapter> <address> <0|1>", 0);
MAKE_PREREQ_PARAMS_FIXED_ARGS(smbus_writeread_params, 5,
"<adapter> <address> <write_value> <read_count>", 0);

#define MAKE_SMBUS_OP(name_, size_, fn_) \
static const struct smbus_op name_ = { \
Expand All @@ -577,6 +651,7 @@ MAKE_SMBUS_OP(smbus_op_quick, SMBUS_QUICK, smbus_write_op);
MAKE_SMBUS_OP(smbus_op_proc_call, SMBUS_PROC_CALL, smbus_process_call_op);
MAKE_SMBUS_OP(smbus_op_block_proc_call, SMBUS_BLOCK_PROC_CALL,
smbus_block_process_call_op);
MAKE_SMBUS_OP(smbus_op_writeread, SMBUS_WRITE_READ, smbus_writeread_op);

#define MAKE_SMBUS_RW_CMDS(size_) \
MAKE_CMD_WITH_PARAMS(smbus_read ##size_, smbus_read, \
Expand All @@ -600,6 +675,8 @@ static const struct cmd_info smbus_cmds[] = {
&smbus_op_proc_call, &smbus_write_params),
MAKE_CMD_WITH_PARAMS(smbus_block_process_call, smbus_process_call,
&smbus_op_block_proc_call, &smbus_write_params),
MAKE_CMD_WITH_PARAMS(smbus_writeread, smbus_writeread,
&smbus_op_writeread, &smbus_writeread_params),
};

MAKE_CMD_GROUP(SMBus, "commands to access the system management bus",
Expand Down