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/* Trivial i2c driver for the maxim DS1621 temperature sensor;
* just implements reading constant conversions with 8-bit
* resolution.
* Demonstrates the implementation of a i2c high-level driver.
*/
/*
* Authorship
* ----------
* This software was created by
* Till Straumann <strauman@slac.stanford.edu>, 2005,
* Stanford Linear Accelerator Center, Stanford University.
*
* Acknowledgement of sponsorship
* ------------------------------
* This software was produced by
* the Stanford Linear Accelerator Center, Stanford University,
* under Contract DE-AC03-76SFO0515 with the Department of Energy.
*
* Government disclaimer of liability
* ----------------------------------
* Neither the United States nor the United States Department of Energy,
* nor any of their employees, makes any warranty, express or implied, or
* assumes any legal liability or responsibility for the accuracy,
* completeness, or usefulness of any data, apparatus, product, or process
* disclosed, or represents that its use would not infringe privately owned
* rights.
*
* Stanford disclaimer of liability
* --------------------------------
* Stanford University makes no representations or warranties, express or
* implied, nor assumes any liability for the use of this software.
*
* Stanford disclaimer of copyright
* --------------------------------
* Stanford University, owner of the copyright, hereby disclaims its
* copyright and all other rights in this software. Hence, anyone may
* freely use it for any purpose without restriction.
*
* Maintenance of notices
* ----------------------
* In the interest of clarity regarding the origin and status of this
* SLAC software, this and all the preceding Stanford University notices
* are to remain affixed to any copy or derivative of this software made
* or distributed by the recipient and are to be affixed to any copy of
* software made or distributed by the recipient that contains a copy or
* derivative of this software.
*
* ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
*/
#include <rtems.h>
#include <rtems/libi2c.h>
#include <libchip/i2c-ds1621.h>
#include <rtems/libio.h>
static rtems_status_code
ds1621_init (rtems_device_major_number major, rtems_device_minor_number minor,
void *arg)
{
int sc;
unsigned char csr[2] = { DS1621_CMD_CSR_ACCESS, 0 }, cmd;
/* First start command acquires a lock for the bus */
/* Initialize; switch continuous conversion on */
sc = rtems_libi2c_start_write_bytes (minor, csr, 1);
if (sc < 0)
return -sc;
sc = rtems_libi2c_start_read_bytes (minor, csr + 1, 1);
if (sc < 0)
return -sc;
csr[1] &= ~DS1621_CSR_1SHOT;
sc = rtems_libi2c_start_write_bytes (minor, csr, 2);
if (sc < 0)
return -sc;
/* Start conversion */
cmd = DS1621_CMD_START_CONV;
sc = rtems_libi2c_start_write_bytes (minor, &cmd, 1);
if (sc < 0)
return -sc;
/* sending 'stop' relinquishes the bus mutex -- don't hold it
* across system calls!
*/
return rtems_libi2c_send_stop (minor);
}
static rtems_status_code
ds1621_read (rtems_device_major_number major, rtems_device_minor_number minor,
void *arg)
{
int sc;
rtems_libio_rw_args_t *rwargs = arg;
unsigned char cmd = DS1621_CMD_READ_TEMP;
sc = rtems_libi2c_start_write_bytes (minor, &cmd, 1);
if (sc < 0)
return -sc;
if (sc < 1)
return RTEMS_IO_ERROR;
sc = rtems_libi2c_start_read_bytes(minor, (unsigned char *)rwargs->buffer, 1);
if (sc < 0) {
rwargs->bytes_moved = 0;
return -sc;
}
rwargs->bytes_moved = 1;
return rtems_libi2c_send_stop (minor);
}
static rtems_driver_address_table myops = {
.initialization_entry = ds1621_init,
.read_entry = ds1621_read,
};
static rtems_libi2c_drv_t my_drv_tbl = {
.ops = &myops,
.size = sizeof (my_drv_tbl),
};
rtems_libi2c_drv_t *i2c_ds1621_driver_descriptor = &my_drv_tbl;
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