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|
/*===============================================================*\
| Project: RTEMS generic MPC5200 BSP |
+-----------------------------------------------------------------+
| Copyright (c) 2005 |
| Embedded Brains GmbH |
| Obere Lagerstr. 30 |
| D-82178 Puchheim |
| Germany |
| rtems@embedded-brains.de |
+-----------------------------------------------------------------+
| The license and distribution terms for this file may be |
| found in the file LICENSE in this distribution or at |
| |
| http://www.rtems.org/license/LICENSE. |
| |
+-----------------------------------------------------------------+
| I2C driver for MPC5200 |
+-----------------------------------------------------------------+
| This file has been adapted from an existing source code file, |
| see the original file header below for reference |
\*===============================================================*/
/* I2C driver for MCF5206eLITE board. I2C bus accessed through on-chip
* MCF5206e MBUS controller.
*
* The purpose of this module is to perform I2C driver initialization
* and serialize I2C transfers.
*
* Copyright (C) 2000 OKTET Ltd., St.-Petersburg, Russia
* Author: Victor V. Vengerov <vvv@oktet.ru>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
*
* http://www.rtems.org/license/LICENSE.
*/
#include <bsp.h>
#include <stdlib.h>
#include <string.h>
#include "../include/i2c.h"
#include "../include/i2cdrv.h"
#include "mpc5200mbus.h"
#ifndef I2C_NUMBER_OF_BUSES
#define I2C_NUMBER_OF_BUSES (2)
#endif
#ifndef I2C_SELECT_BUS
#define I2C_SELECT_BUS(bus)
#endif
/*
* Few I2C transfers may be posted simultaneously, but MBUS driver is able
* to process it one-by-one. To serialize transfers, function i2c_transfer
* put transfer information to the queue and initiate new transfers if MBUS
* driver is not busy. When driver is busy, next transfer is dequeued
* when current active transfer is finished.
*/
/*
* i2c_qel - I2C transfers queue element; contain information about
* delayed transfer
*/
typedef struct i2c_qel {
i2c_bus_number bus; /* I2C bus number */
i2c_message *msg; /* pointer to the transfer' messages array */
int nmsg; /* number of messages in transfer */
i2c_transfer_done done; /* transfer done callback function */
void * done_arg_ptr; /* arbitrary arg pointer to done callback */
} i2c_qel;
/* Memory for I2C transfer queue. This queue represented like a ring buffer */
static i2c_qel *tqueue;
/* Maximum number of elements in transfer queue */
static int tqueue_size;
/* Position of next free element in a ring buffer */
static volatile int tqueue_head;
/* Position of the first element in transfer queue */
static volatile int tqueue_tail;
/* MBus I2C bus controller busy flag */
static volatile bool mbus_busy;
/* MBus I2C bus controller descriptor */
static mpc5200mbus mbus[I2C_NUMBER_OF_BUSES];
/* Clock rate selected for each of bus */
static int i2cdrv_bus_clock_div[I2C_NUMBER_OF_BUSES];
/* Currently selected I2C bus clock rate */
static int i2cdrv_bus_clock_div_current;
/* Forward function declaration */
static void i2cdrv_unload(void);
/* i2cdrv_done --
* Callback function which is called from MBus low-level driver when
* transfer is finished.
*/
static void
i2cdrv_done(void * arg_ptr)
{
rtems_interrupt_level level;
i2c_qel *qel = tqueue + tqueue_tail;
qel->done(qel->done_arg_ptr);
rtems_interrupt_disable(level);
tqueue_tail = (tqueue_tail + 1) % tqueue_size;
mbus_busy = false;
rtems_interrupt_enable(level);
i2cdrv_unload();
}
/* i2cdrv_unload --
* If MBUS controller is not busy and transfer waiting in a queue,
* initiate processing of the next transfer in queue.
*/
static void
i2cdrv_unload(void)
{
rtems_interrupt_level level;
i2c_qel *qel;
rtems_status_code sc;
rtems_interrupt_disable(level);
if (!mbus_busy && (tqueue_head != tqueue_tail))
{
mbus_busy = true;
rtems_interrupt_enable(level);
qel = tqueue + tqueue_tail;
I2C_SELECT_BUS(qel->bus);
if (i2cdrv_bus_clock_div[qel->bus] != i2cdrv_bus_clock_div_current)
{
i2cdrv_bus_clock_div_current = i2cdrv_bus_clock_div[qel->bus];
mpc5200mbus_select_clock_divider(&mbus[qel->bus], i2cdrv_bus_clock_div_current);
}
sc = mpc5200mbus_i2c_transfer(&mbus[qel->bus], qel->nmsg, qel->msg,
i2cdrv_done,qel);
if (sc != RTEMS_SUCCESSFUL)
{
int i;
for (i = 0; i < qel->nmsg; i++)
{
qel->msg[i].status = I2C_RESOURCE_NOT_AVAILABLE;
}
i2cdrv_done(qel);
}
}
else
{
rtems_interrupt_enable(level);
}
}
/* i2c_transfer --
* Initiate multiple-messages transfer over specified I2C bus or
* put request into queue if bus or some other resource is busy. (This
* is non-blocking function).
*
* PARAMETERS:
* bus - I2C bus number
* nmsg - number of messages
* msg - pointer to messages array
* done - function which is called when transfer is finished
* done_arg_ptr - arbitrary argument pointer passed to done funciton
*
* RETURNS:
* RTEMS_SUCCESSFUL if transfer initiated successfully, or error
* code if something failed.
*/
rtems_status_code
i2c_transfer(i2c_bus_number bus, int nmsg, i2c_message *msg,
i2c_transfer_done done, void * done_arg_ptr)
{
i2c_qel qel;
rtems_interrupt_level level;
if (bus >= I2C_NUMBER_OF_BUSES)
{
return RTEMS_INVALID_NUMBER;
}
if (msg == NULL)
{
return RTEMS_INVALID_ADDRESS;
}
qel.bus = bus;
qel.msg = msg;
qel.nmsg = nmsg;
qel.done = done;
qel.done_arg_ptr = done_arg_ptr;
rtems_interrupt_disable(level);
if ((tqueue_head + 1) % tqueue_size == tqueue_tail)
{
rtems_interrupt_enable(level);
return RTEMS_TOO_MANY;
}
memcpy(tqueue + tqueue_head, &qel, sizeof(qel));
tqueue_head = (tqueue_head + 1) % tqueue_size;
rtems_interrupt_enable(level);
i2cdrv_unload();
return RTEMS_SUCCESSFUL;
}
/* i2cdrv_initialize --
* I2C driver initialization (rtems I/O driver primitive)
*/
rtems_device_driver
i2cdrv_initialize(rtems_device_major_number major,
rtems_device_minor_number minor,
void *arg)
{
int i;
rtems_status_code sc;
mbus_busy = false;
tqueue_tail = tqueue_head = 0;
tqueue_size = 32;
tqueue = calloc(tqueue_size, sizeof(i2c_qel));
for (i = 0; i < I2C_NUMBER_OF_BUSES; i++)
{
mbus[i].bus_idx = i;
sc = mpc5200mbus_initialize(&mbus[i]);
if (sc != RTEMS_SUCCESSFUL)
return sc;
}
for (i = 0; i < I2C_NUMBER_OF_BUSES; i++)
{
sc = i2c_select_clock_rate(i, 100000);
if (sc != RTEMS_SUCCESSFUL)
return sc;
}
i2cdrv_bus_clock_div_current = -1;
return RTEMS_SUCCESSFUL;
}
/* i2c_select_clock_rate --
* select I2C bus clock rate for specified bus. Some bus controller do not
* allow to select arbitrary clock rate; in this case nearest possible
* slower clock rate is selected.
*
* PARAMETERS:
* bus - I2C bus number
* bps - data transfer rate for this bytes in bits per second
*
* RETURNS:
* RTEMS_SUCCESSFUL, if operation performed successfully,
* RTEMS_INVALID_NUMBER, if wrong bus number is specified,
* RTEMS_UNSATISFIED, if bus do not support data transfer rate selection
* or specified data transfer rate could not be used.
*/
rtems_status_code
i2c_select_clock_rate(i2c_bus_number bus, int bps)
{
int div;
if (bus >= I2C_NUMBER_OF_BUSES)
return RTEMS_INVALID_NUMBER;
if (bps == 0)
return RTEMS_UNSATISFIED;
div = IPB_CLOCK / bps;
i2cdrv_bus_clock_div[bus] = div;
return RTEMS_SUCCESSFUL;
}
/* i2c_poll --
* Poll I2C bus controller for events and hanle it. This function is
* used when I2C driver operates in poll-driven mode.
*
* PARAMETERS:
* bus - bus number to be polled
*
* RETURNS:
* none
*/
void
i2c_poll(i2c_bus_number bus)
{
mpc5200mbus_poll(&mbus[bus]);
}
|
