root/i2c-tools/trunk/py-smbus/smbusmodule.c

/*
 * smbusmodule.c - Python bindings for Linux SMBus access through i2c-dev
 * Copyright (C) 2005-2007 Mark M. Hoffman <mhoffman@lightlink.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include <Python.h>
#include "structmember.h"
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>

/*
** These are required to build this module against Linux older than 2.6.23.
*/
#ifndef I2C_SMBUS_I2C_BLOCK_BROKEN
#undef I2C_SMBUS_I2C_BLOCK_DATA
#define I2C_SMBUS_I2C_BLOCK_BROKEN      6
#define I2C_SMBUS_I2C_BLOCK_DATA        8
#endif

PyDoc_STRVAR(SMBus_module_doc,
        "This module defines an object type that allows SMBus transactions\n"
        "on Linux hosts.  The host kernel must have I2C support, I2C device\n"
        "interface support, and a bus adapter driver.  All of these can be\n"
        "either built-in to the kernel, or loaded from modules.\n"
        "\n"
        "Because the I2C device interface is opened R/W, users of this\n"
        "module usually must have root permissions.\n");

typedef struct {
        PyObject_HEAD

        int fd;         /* open file descriptor: /dev/i2c-?, or -1 */
        int addr;       /* current client SMBus address */
        int pec;        /* !0 => Packet Error Codes enabled */
} SMBus;

static PyObject *
SMBus_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
        SMBus *self;

        if ((self = (SMBus *)type->tp_alloc(type, 0)) == NULL)
                return NULL;

        self->fd = -1;
        self->addr = -1;
        self->pec = 0;

        return (PyObject *)self;
}

PyDoc_STRVAR(SMBus_close_doc,
        "close()\n\n"
        "Disconnects the object from the bus.\n");

static PyObject *
SMBus_close(SMBus *self)
{
        if ((self->fd != -1) && (close(self->fd) == -1)) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        self->fd = -1;
        self->addr = -1;
        self->pec = 0;

        Py_INCREF(Py_None);
        return Py_None;
}

static void
SMBus_dealloc(SMBus *self)
{
        PyObject *ref = SMBus_close(self);
        Py_XDECREF(ref);

        self->ob_type->tp_free((PyObject *)self);
}

#define MAXPATH 16

PyDoc_STRVAR(SMBus_open_doc,
        "open(bus)\n\n"
        "Connects the object to the specified SMBus.\n");

static PyObject *
SMBus_open(SMBus *self, PyObject *args, PyObject *kwds)
{
        int bus;
        char path[MAXPATH];

        static char *kwlist[] = {"bus", NULL};

        if (!PyArg_ParseTupleAndKeywords(args, kwds, "i:open", kwlist, &bus))
                return NULL;

        if (snprintf(path, MAXPATH, "/dev/i2c-%d", bus) >= MAXPATH) {
                PyErr_SetString(PyExc_OverflowError,
                        "Bus number is invalid.");
                return NULL;
        }

        if ((self->fd = open(path, O_RDWR, 0)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

static int
SMBus_init(SMBus *self, PyObject *args, PyObject *kwds)
{
        int bus = -1;

        static char *kwlist[] = {"bus", NULL};

        if (!PyArg_ParseTupleAndKeywords(args, kwds, "|i:__init__",
                        kwlist, &bus))
                return -1;

        if (bus >= 0) {
                SMBus_open(self, args, kwds);
                if (PyErr_Occurred())
                        return -1;
        }

        return 0;
}

/*
 * private helper function, 0 => success, !0 => error
 */
static int
SMBus_set_addr(SMBus *self, int addr)
{
        int ret = 0;

        if (self->addr != addr) {
                ret = ioctl(self->fd, I2C_SLAVE, addr);
                self->addr = addr;
        }

        return ret;
}

#define SMBus_SET_ADDR(self, addr) do { \
        if (SMBus_set_addr(self, addr)) { \
                PyErr_SetFromErrno(PyExc_IOError); \
                return NULL; \
        } \
} while(0)

PyDoc_STRVAR(SMBus_write_quick_doc,
        "write_quick(addr)\n\n"
        "Perform SMBus Quick transaction.\n");

static PyObject *
SMBus_write_quick(SMBus *self, PyObject *args)
{
        int addr;
        __s32 result;

        if (!PyArg_ParseTuple(args, "i:write_quick", &addr))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_write_quick(self->fd, I2C_SMBUS_WRITE))) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

PyDoc_STRVAR(SMBus_read_byte_doc,
        "read_byte(addr) -> result\n\n"
        "Perform SMBus Read Byte transaction.\n");

static PyObject *
SMBus_read_byte(SMBus *self, PyObject *args)
{
        int addr;
        __s32 result;

        if (!PyArg_ParseTuple(args, "i:read_byte", &addr))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_read_byte(self->fd)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        return Py_BuildValue("l", (long)result);
}

PyDoc_STRVAR(SMBus_write_byte_doc,
        "write_byte(addr, val)\n\n"
        "Perform SMBus Write Byte transaction.\n");

static PyObject *
SMBus_write_byte(SMBus *self, PyObject *args)
{
        int addr, val;
        __s32 result;

        if (!PyArg_ParseTuple(args, "ii:write_byte", &addr, &val))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_write_byte(self->fd, (__u8)val)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

PyDoc_STRVAR(SMBus_read_byte_data_doc,
        "read_byte_data(addr, cmd) -> result\n\n"
        "Perform SMBus Read Byte Data transaction.\n");

static PyObject *
SMBus_read_byte_data(SMBus *self, PyObject *args)
{
        int addr, cmd;
        __s32 result;

        if (!PyArg_ParseTuple(args, "ii:read_byte_data", &addr, &cmd))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_read_byte_data(self->fd, (__u8)cmd)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        return Py_BuildValue("l", (long)result);
}

PyDoc_STRVAR(SMBus_write_byte_data_doc,
        "write_byte_data(addr, cmd, val)\n\n"
        "Perform SMBus Write Byte Data transaction.\n");

static PyObject *
SMBus_write_byte_data(SMBus *self, PyObject *args)
{
        int addr, cmd, val;
        __s32 result;

        if (!PyArg_ParseTuple(args, "iii:write_byte_data", &addr, &cmd, &val))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_write_byte_data(self->fd,
                                (__u8)cmd, (__u8)val)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

PyDoc_STRVAR(SMBus_read_word_data_doc,
        "read_word_data(addr, cmd) -> result\n\n"
        "Perform SMBus Read Word Data transaction.\n");

static PyObject *
SMBus_read_word_data(SMBus *self, PyObject *args)
{
        int addr, cmd;
        __s32 result;

        if (!PyArg_ParseTuple(args, "ii:read_word_data", &addr, &cmd))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_read_word_data(self->fd, (__u8)cmd)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        return Py_BuildValue("l", (long)result);
}

PyDoc_STRVAR(SMBus_write_word_data_doc,
        "write_word_data(addr, cmd, val)\n\n"
        "Perform SMBus Write Word Data transaction.\n");

static PyObject *
SMBus_write_word_data(SMBus *self, PyObject *args)
{
        int addr, cmd, val;
        __s32 result;

        if (!PyArg_ParseTuple(args, "iii:write_word_data", &addr, &cmd, &val))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_write_word_data(self->fd,
                                (__u8)cmd, (__u16)val)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

PyDoc_STRVAR(SMBus_process_call_doc,
        "process_call(addr, cmd, val)\n\n"
        "Perform SMBus Process Call transaction.\n");

static PyObject *
SMBus_process_call(SMBus *self, PyObject *args)
{
        int addr, cmd, val;
        __s32 result;

        if (!PyArg_ParseTuple(args, "iii:process_call", &addr, &cmd, &val))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        if ((result = i2c_smbus_process_call(self->fd,
                                (__u8)cmd, (__u16)val)) == -1) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

/*
 * private helper function; returns a new list of integers
 */
static PyObject *
SMBus_buf_to_list(__u8 const *buf, int len)
{
        PyObject *list = PyList_New(len);
        int ii;

        if (list == NULL)
                return NULL;

        for (ii = 0; ii < len; ii++) {
                PyObject *val = Py_BuildValue("l", (long)buf[ii]);
                PyList_SET_ITEM(list, ii, val);
        }
        return list;
}

PyDoc_STRVAR(SMBus_read_block_data_doc,
        "read_block_data(addr, cmd) -> results\n\n"
        "Perform SMBus Read Block Data transaction.\n");

static PyObject *
SMBus_read_block_data(SMBus *self, PyObject *args)
{
        int addr, cmd;
        union i2c_smbus_data data;

        if (!PyArg_ParseTuple(args, "ii:read_block_data", &addr, &cmd))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        /* save a bit of code by calling the access function directly */
        if (i2c_smbus_access(self->fd, I2C_SMBUS_READ, (__u8)cmd,
                                I2C_SMBUS_BLOCK_DATA, &data)) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        /* first byte of the block contains (remaining) data length */
        return SMBus_buf_to_list(&data.block[1], data.block[0]);
}

/*
 * private helper function: convert an integer list to union i2c_smbus_data
 */
static int
SMBus_list_to_data(PyObject *list, union i2c_smbus_data *data)
{
        static char *msg = "Third argument must be a list of at least one, "
                                "but not more than 32 integers";
        int ii, len;

        if (!PyList_Check(list)) {
                PyErr_SetString(PyExc_TypeError, msg);
                return 0; /* fail */
        }

        if ((len = PyList_GET_SIZE(list)) > 32) {
                PyErr_SetString(PyExc_OverflowError, msg);
                return 0; /* fail */
        }

        /* first byte is the length */
        data->block[0] = (__u8)len;

        for (ii = 0; ii < len; ii++) {
                PyObject *val = PyList_GET_ITEM(list, ii);
                if (!PyInt_Check(val)) {
                        PyErr_SetString(PyExc_TypeError, msg);
                        return 0; /* fail */
                }
                data->block[ii+1] = (__u8)PyInt_AS_LONG(val);
        }

        return 1; /* success */
}

PyDoc_STRVAR(SMBus_write_block_data_doc,
        "write_block_data(addr, cmd, [vals])\n\n"
        "Perform SMBus Write Block Data transaction.\n");

static PyObject *
SMBus_write_block_data(SMBus *self, PyObject *args)
{
        int addr, cmd;
        union i2c_smbus_data data;

        if (!PyArg_ParseTuple(args, "iiO&:write_block_data", &addr, &cmd,
                                SMBus_list_to_data, &data))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        /* save a bit of code by calling the access function directly */
        if (i2c_smbus_access(self->fd, I2C_SMBUS_WRITE, (__u8)cmd,
                                I2C_SMBUS_BLOCK_DATA, &data)) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

PyDoc_STRVAR(SMBus_block_process_call_doc,
        "block_process_call(addr, cmd, [vals]) -> results\n\n"
        "Perform SMBus Block Process Call transaction.\n");

static PyObject *
SMBus_block_process_call(SMBus *self, PyObject *args)
{
        int addr, cmd;
        union i2c_smbus_data data;

        if (!PyArg_ParseTuple(args, "iiO&:block_process_call", &addr, &cmd,
                        SMBus_list_to_data, &data))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        /* save a bit of code by calling the access function directly */
        if (i2c_smbus_access(self->fd, I2C_SMBUS_WRITE, (__u8)cmd,
                                I2C_SMBUS_BLOCK_PROC_CALL, &data)) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        /* first byte of the block contains (remaining) data length */
        return SMBus_buf_to_list(&data.block[1], data.block[0]);
}

PyDoc_STRVAR(SMBus_read_i2c_block_data_doc,
        "read_i2c_block_data(addr, cmd, len=32) -> results\n\n"
        "Perform I2C Block Read transaction.\n");

static PyObject *
SMBus_read_i2c_block_data(SMBus *self, PyObject *args)
{
        int addr, cmd, len=32;
        union i2c_smbus_data data;

        if (!PyArg_ParseTuple(args, "ii|i:read_i2c_block_data", &addr, &cmd,
                        &len))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        data.block[0] = len;
        /* save a bit of code by calling the access function directly */
        if (i2c_smbus_access(self->fd, I2C_SMBUS_READ, (__u8)cmd,
                                len == 32 ? I2C_SMBUS_I2C_BLOCK_BROKEN:
                                I2C_SMBUS_I2C_BLOCK_DATA, &data)) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        /* first byte of the block contains (remaining) data length */
        return SMBus_buf_to_list(&data.block[1], data.block[0]);
}

PyDoc_STRVAR(SMBus_write_i2c_block_data_doc,
        "write_i2c_block_data(addr, cmd, [vals])\n\n"
        "Perform I2C Block Write transaction.\n");

static PyObject *
SMBus_write_i2c_block_data(SMBus *self, PyObject *args)
{
        int addr, cmd;
        union i2c_smbus_data data;

        if (!PyArg_ParseTuple(args, "iiO&:write_i2c_block_data", &addr, &cmd,
                        SMBus_list_to_data, &data))
                return NULL;

        SMBus_SET_ADDR(self, addr);

        /* save a bit of code by calling the access function directly */
        if (i2c_smbus_access(self->fd, I2C_SMBUS_WRITE, (__u8)cmd,
                                I2C_SMBUS_I2C_BLOCK_BROKEN, &data)) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

        Py_INCREF(Py_None);
        return Py_None;
}

PyDoc_STRVAR(SMBus_type_doc,
        "SMBus([bus]) -> SMBus\n\n"
        "Return a new SMBus object that is (optionally) connected to the\n"
        "specified I2C device interface.\n");

static PyMethodDef SMBus_methods[] = {
        {"open", (PyCFunction)SMBus_open, METH_VARARGS | METH_KEYWORDS,
                SMBus_open_doc},
        {"close", (PyCFunction)SMBus_close, METH_NOARGS,
                SMBus_close_doc},
        {"write_quick", (PyCFunction)SMBus_write_quick, METH_VARARGS,
                SMBus_write_quick_doc},
        {"read_byte", (PyCFunction)SMBus_read_byte, METH_VARARGS,
                SMBus_read_byte_doc},
        {"write_byte", (PyCFunction)SMBus_write_byte, METH_VARARGS,
                SMBus_write_byte_doc},
        {"read_byte_data", (PyCFunction)SMBus_read_byte_data, METH_VARARGS,
                SMBus_read_byte_data_doc},
        {"write_byte_data", (PyCFunction)SMBus_write_byte_data, METH_VARARGS,
                SMBus_write_byte_data_doc},
        {"read_word_data", (PyCFunction)SMBus_read_word_data, METH_VARARGS,
                SMBus_read_word_data_doc},
        {"write_word_data", (PyCFunction)SMBus_write_word_data, METH_VARARGS,
                SMBus_write_word_data_doc},
        {"process_call", (PyCFunction)SMBus_process_call, METH_VARARGS,
                SMBus_process_call_doc},
        {"read_block_data", (PyCFunction)SMBus_read_block_data, METH_VARARGS,
                SMBus_read_block_data_doc},
        {"write_block_data", (PyCFunction)SMBus_write_block_data, METH_VARARGS,
                SMBus_write_block_data_doc},
        {"block_process_call", (PyCFunction)SMBus_block_process_call,
                METH_VARARGS, SMBus_block_process_call_doc},
        {"read_i2c_block_data", (PyCFunction)SMBus_read_i2c_block_data,
                METH_VARARGS, SMBus_read_i2c_block_data_doc},
        {"write_i2c_block_data", (PyCFunction)SMBus_write_i2c_block_data,
                METH_VARARGS, SMBus_write_i2c_block_data_doc},
        {NULL},
};

static PyObject *
SMBus_get_pec(SMBus *self, void *closure)
{
        PyObject *result = self->pec ? Py_True : Py_False;
        Py_INCREF(result);
        return result;
}

static int
SMBus_set_pec(SMBus *self, PyObject *val, void *closure)
{
        int pec;

        pec = PyObject_IsTrue(val);

        if (val == NULL) {
                PyErr_SetString(PyExc_TypeError,
                        "Cannot delete attribute");
                return -1;
        }
        else if (pec == -1) {
                PyErr_SetString(PyExc_TypeError, 
                        "The pec attribute must be a boolean.");
                return -1;
        }

        if (self->pec != pec) {
                if (ioctl(self->fd, I2C_PEC, pec)) {
                        PyErr_SetFromErrno(PyExc_IOError);
                        return -1;
                }
                self->pec = pec;
        }

        return 0;
}

static PyGetSetDef SMBus_getset[] = {
        {"pec", (getter)SMBus_get_pec, (setter)SMBus_set_pec,
                        "True if Packet Error Codes (PEC) are enabled"},
        {NULL},
};

static PyTypeObject SMBus_type = {
        PyObject_HEAD_INIT(NULL)
        0,                              /* ob_size */
        "SMBus",                        /* tp_name */
        sizeof(SMBus),                  /* tp_basicsize */
        0,                              /* tp_itemsize */
        (destructor)SMBus_dealloc,      /* tp_dealloc */
        0,                              /* tp_print */
        0,                              /* tp_getattr */
        0,                              /* tp_setattr */
        0,                              /* tp_compare */
        0,                              /* tp_repr */
        0,                              /* tp_as_number */
        0,                              /* tp_as_sequence */
        0,                              /* tp_as_mapping */
        0,                              /* tp_hash */
        0,                              /* tp_call */
        0,                              /* tp_str */
        0,                              /* tp_getattro */
        0,                              /* tp_setattro */
        0,                              /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT,             /* tp_flags */
        SMBus_type_doc,                 /* tp_doc */
        0,                              /* tp_traverse */
        0,                              /* tp_clear */
        0,                              /* tp_richcompare */
        0,                              /* tp_weaklistoffset */
        0,                              /* tp_iter */
        0,                              /* tp_iternext */
        SMBus_methods,                  /* tp_methods */
        0,                              /* tp_members */
        SMBus_getset,                   /* tp_getset */
        0,                              /* tp_base */
        0,                              /* tp_dict */
        0,                              /* tp_descr_get */
        0,                              /* tp_descr_set */
        0,                              /* tp_dictoffset */
        (initproc)SMBus_init,           /* tp_init */
        0,                              /* tp_alloc */
        SMBus_new,                      /* tp_new */
};

static PyMethodDef SMBus_module_methods[] = {
        {NULL}
};

#ifndef PyMODINIT_FUNC  /* declarations for DLL import/export */
#define PyMODINIT_FUNC void
#endif
PyMODINIT_FUNC
initsmbus(void) 
{
        PyObject* m;

        if (PyType_Ready(&SMBus_type) < 0)
                return;

        m = Py_InitModule3("smbus", SMBus_module_methods, SMBus_module_doc);

        Py_INCREF(&SMBus_type);
        PyModule_AddObject(m, "SMBus", (PyObject *)&SMBus_type);
}