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incubator-nuttx/drivers/timers/mcp794xx.c

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/****************************************************************************
* drivers/timers/mcp794xx.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <time.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/signal.h>
#include <nuttx/arch.h>
#include <nuttx/i2c/i2c_master.h>
#include <nuttx/timers/mcp794xx.h>
#include "mcp794xx.h"
#ifdef CONFIG_RTC_MCP794XX
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MCP794XX_OSCRUN_READ_RETRY 5 /* How many time to read OSCRUN status */
/* Configuration ************************************************************/
/* This RTC implementation supports only date/time RTC hardware */
#ifndef CONFIG_RTC_DATETIME
# error CONFIG_RTC_DATETIME must be set to use this driver
#endif
#ifdef CONFIG_RTC_HIRES
# error CONFIG_RTC_HIRES must NOT be set with this driver
#endif
#ifndef CONFIG_MCP794XX_I2C_FREQUENCY
# error CONFIG_MCP794XX_I2C_FREQUENCY is not configured
# define CONFIG_MCP794XX_I2C_FREQUENCY 400000
#endif
#if CONFIG_MCP794XX_I2C_FREQUENCY > 400000
# error CONFIG_MCP794XX_I2C_FREQUENCY is out of range
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure describes the state of the MCP794XX chip.
* Only a single RTC is supported.
*/
struct mcp794xx_dev_s
{
FAR struct i2c_master_s *i2c; /* Contained reference to the I2C bus driver. */
uint8_t addr; /* The I2C device address. */
};
/****************************************************************************
* Public Data
****************************************************************************/
/* g_rtc_enabled is set true after the RTC has successfully initialized */
volatile bool g_rtc_enabled = false;
/****************************************************************************
* Private Data
****************************************************************************/
/* The state of the MCP794XX chip. Only a single RTC is supported */
static struct mcp794xx_dev_s g_mcp794xx;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: rtc_dumptime
*
* Description:
* Show the broken out time.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
****************************************************************************/
#ifdef CONFIG_DEBUG_RTC_INFO
static void rtc_dumptime(FAR struct tm *tp, FAR const char *msg)
{
rtcinfo("%s:\n", msg);
rtcinfo(" tm_sec: %08x\n", tp->tm_sec);
rtcinfo(" tm_min: %08x\n", tp->tm_min);
rtcinfo(" tm_hour: %08x\n", tp->tm_hour);
rtcinfo(" tm_mday: %08x\n", tp->tm_mday);
rtcinfo(" tm_mon: %08x\n", tp->tm_mon);
rtcinfo(" tm_year: %08x\n", tp->tm_year);
rtcinfo(" tm_wday: %08x\n", tp->tm_wday);
rtcinfo(" tm_yday: %08x\n", tp->tm_yday);
rtcinfo(" tm_isdst: %08x\n", tp->tm_isdst);
}
#else
# define rtc_dumptime(tp, msg)
#endif
/****************************************************************************
* Name: rtc_bin2bcd
*
* Description:
* Converts a 2 digit binary to BCD format
*
* Input Parameters:
* value - The byte to be converted.
*
* Returned Value:
* The value in BCD representation
*
****************************************************************************/
static uint8_t rtc_bin2bcd(int value)
{
uint8_t msbcd = 0;
while (value >= 10)
{
msbcd++;
value -= 10;
}
return (msbcd << 4) | value;
}
/****************************************************************************
* Name: rtc_bcd2bin
*
* Description:
* Convert from 2 digit BCD to binary.
*
* Input Parameters:
* value - The BCD value to be converted.
*
* Returned Value:
* The value in binary representation
*
****************************************************************************/
static int rtc_bcd2bin(uint8_t value)
{
int tens = ((int)value >> 4) * 10;
return tens + (value & 0x0f);
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mcp794xx_rtc_initialize
*
* Description:
* Initialize the hardware RTC per the selected configuration. This
* function is called once during the OS initialization sequence by board-
* specific logic.
*
* After mcp794xx_rtc_initialize() is called, the OS function
* clock_synchronize() should also be called to synchronize the system
* timer to a hardware RTC. That operation is normally performed
* automatically by the system during clock initialization. However, when
* an external RTC is used, the board logic will need to explicitly re-
* synchronize the system timer to the RTC when the RTC becomes available.
*
* Input Parameters:
* i2c - An instance of the I2C interface used to access the MCP794XX
* device
* addr - The (7-bit) I2C address of the MCP794XX device
*
* Returned Value:
* Zero (OK) on success; a negated errno on failure
*
****************************************************************************/
int mcp794xx_rtc_initialize(FAR struct i2c_master_s *i2c, uint8_t addr)
{
/* Remember the i2c device and claim that the RTC is enabled */
g_mcp794xx.i2c = i2c;
g_mcp794xx.addr = addr;
g_rtc_enabled = true;
return OK;
}
/****************************************************************************
* Name: up_rtc_getdatetime
*
* Description:
* Get the current date and time from the date/time RTC. This interface
* is only supported by the date/time RTC hardware implementation.
* It is used to replace the system timer. It is only used by the RTOS
* during initialization to set up the system time when CONFIG_RTC and
* CONFIG_RTC_DATETIME are selected (and CONFIG_RTC_HIRES is not).
*
* NOTE: Some date/time RTC hardware is capability of sub-second accuracy.
* That sub-second accuracy is lost in this interface. However, since the
* system time is reinitialized on each power-up/reset, there will be no
* timing inaccuracy in the long run.
*
* Input Parameters:
* tp - The location to return the high resolution time value.
*
* Returned Value:
* Zero (OK) on success; a negated errno on failure
*
****************************************************************************/
int up_rtc_getdatetime(FAR struct tm *tp)
{
struct i2c_msg_s msg[4];
uint8_t secaddr;
uint8_t buffer[7];
uint8_t seconds;
int ret;
/* If this function is called before the RTC has been initialized (and it
* will be), then just return the data/time of the epoch, 12:00 am, Jan 1,
* 1970.
*/
if (!g_rtc_enabled)
{
tp->tm_sec = 0;
tp->tm_min = 0;
tp->tm_hour = 0;
/* Jan 1, 1970 was a Thursday */
tp->tm_wday = 4;
tp->tm_mday = 1;
tp->tm_mon = 0;
tp->tm_year = 70;
return -EAGAIN;
}
/* The start address of the read is the seconds address (0x00)
* The chip increments the address to read from after each read.
*/
secaddr = MCP794XX_REG_RTCSEC;
msg[0].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[0].addr = g_mcp794xx.addr;
msg[0].flags = I2C_M_NOSTOP;
msg[0].buffer = &secaddr;
msg[0].length = 1;
/* Setup the read. Seven (7) registers will be read.
* (Seconds, minutes, hours, wday, date, month and year)
*/
msg[1].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[1].addr = g_mcp794xx.addr;
msg[1].flags = I2C_M_READ;
msg[1].buffer = buffer;
msg[1].length = 7;
/* Read the seconds register again */
msg[2].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[2].addr = g_mcp794xx.addr;
msg[2].flags = I2C_M_NOSTOP;
msg[2].buffer = &secaddr;
msg[2].length = 1;
msg[3].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[3].addr = g_mcp794xx.addr;
msg[3].flags = I2C_M_READ;
msg[3].buffer = &seconds;
msg[3].length = 1;
/* Perform the transfer. The transfer may be performed repeatedly of the
* seconds values decreases, meaning that was a rollover in the seconds.
*/
do
{
ret = I2C_TRANSFER(g_mcp794xx.i2c, msg, 4);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
}
while ((buffer[0] & MCP794XX_RTCSEC_BCDMASK) >
(seconds & MCP794XX_RTCSEC_BCDMASK));
/* Format the return time */
/* Return seconds (0-59) */
tp->tm_sec = rtc_bcd2bin(buffer[0] & MCP794XX_RTCSEC_BCDMASK);
/* Return minutes (0-59) */
tp->tm_min = rtc_bcd2bin(buffer[1] & MCP794XX_RTCMIN_BCDMASK);
/* Return hour (0-23). This assumes 24-hour time was set. */
tp->tm_hour = rtc_bcd2bin(buffer[2] & MCP794XX_RTCHOUR_BCDMASK);
/* Return the day of the week (0-6) */
tp->tm_wday = (rtc_bcd2bin(buffer[3]) & MCP794XX_RTCWKDAY_BCDMASK) - 1;
/* Return the day of the month (1-31) */
tp->tm_mday = rtc_bcd2bin(buffer[4] & MCP794XX_RTCDATE_BCDMASK);
/* Return the month (0-11) */
tp->tm_mon = rtc_bcd2bin(buffer[5] & MCP794XX_RTCMTH_BCDMASK) - 1;
/* Return the years since 1900 */
tp->tm_year = rtc_bcd2bin(buffer[6] & MCP794XX_RTCYEAR_BCDMASK);
/* The Year is stored in the RTC starting from 2001. We need to convert it
* to POSIX format that expects the year starting from 1900.
*/
tp->tm_year += 101;
rtc_dumptime(tp, "Returning");
return OK;
}
/****************************************************************************
* Name: up_rtc_settime
*
* Description:
* Set the RTC to the provided time. All RTC implementations must be able
* to set their time based on a standard timespec.
*
* Input Parameters:
* tp - the time to use
*
* Returned Value:
* Zero (OK) on success; a negated errno on failure
*
****************************************************************************/
int up_rtc_settime(FAR const struct timespec *tp)
{
struct i2c_msg_s msg[3];
struct tm newtm;
time_t newtime;
uint8_t buffer[8];
uint8_t wkdayaddr;
uint8_t wkday;
int ret;
int retries = MCP794XX_OSCRUN_READ_RETRY;
/* If this function is called before the RTC has been initialized then
* just return an error.
*/
if (!g_rtc_enabled)
{
return -EAGAIN;
}
rtcinfo("Setting time tp=(%d,%d)\n", (int)tp->tv_sec, (int)tp->tv_nsec);
/* Get the broken out time */
newtime = (time_t)tp->tv_sec;
if (tp->tv_nsec >= 500000000)
{
/* Round up */
newtime++;
}
if (localtime_r(&newtime, &newtm) == NULL)
{
rtcerr("ERROR: localtime_r failed\n");
return -EINVAL;
}
rtc_dumptime(&newtm, "New time");
/* Stop the oscillator first. */
buffer[0] = MCP794XX_REG_RTCSEC;
buffer[1] = 0;
msg[0].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[0].addr = g_mcp794xx.addr;
msg[0].flags = 0;
msg[0].buffer = buffer;
msg[0].length = 2;
ret = I2C_TRANSFER(g_mcp794xx.i2c, msg, 1);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
/* Verify that the oscillator is not running. */
wkdayaddr = MCP794XX_REG_RTCWKDAY;
msg[0].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[0].addr = g_mcp794xx.addr;
msg[0].flags = I2C_M_NOSTOP;
msg[0].buffer = &wkdayaddr;
msg[0].length = 1;
msg[1].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[1].addr = g_mcp794xx.addr;
msg[1].flags = I2C_M_READ;
msg[1].buffer = &wkday;
msg[1].length = 1;
retries = MCP794XX_OSCRUN_READ_RETRY;
do
{
/* Give time to oscillator to change its status */
nxsig_usleep(10000);
ret = I2C_TRANSFER(g_mcp794xx.i2c, msg, 2);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
retries--;
}
while ((wkday & MCP794XX_RTCWKDAY_OSCRUN) != 0 && retries > 0);
/* Construct the message */
/* Write starting with the seconds register */
buffer[0] = MCP794XX_REG_RTCSEC;
/* Save seconds (0-59) converted to BCD. And keep ST cleared. */
buffer[1] = rtc_bin2bcd(newtm.tm_sec);
/* Save minutes (0-59) converted to BCD */
buffer[2] = rtc_bin2bcd(newtm.tm_min);
/* Save hour (0-23) with 24-hour time indication */
buffer[3] = rtc_bin2bcd(newtm.tm_hour);
/* Save the day of the week (1-7) and enable VBAT. */
buffer[4] = rtc_bin2bcd(newtm.tm_wday + 1) | MCP794XX_RTCWKDAY_VBATEN;
/* Save the day of the month (1-31) */
buffer[5] = rtc_bin2bcd(newtm.tm_mday);
/* Save the month (1-12) */
buffer[6] = rtc_bin2bcd(newtm.tm_mon + 1);
/* Save the year (00-99) */
/* First we need to convert "tm_year" to value starting from 2001.
* The "tm_year" in POSIX is relative to 1900, so 2019 is 119,
* so you just need to subtract 101: year = (1900 + value) - 2001
*/
buffer[7] = rtc_bin2bcd(newtm.tm_year - 101);
msg[0].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[0].addr = g_mcp794xx.addr;
msg[0].flags = 0;
msg[0].buffer = buffer;
msg[0].length = 8;
ret = I2C_TRANSFER(g_mcp794xx.i2c, msg, 1);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
/* Start the oscillator. */
buffer[1] |= MCP794XX_RTCSEC_ST;
msg[0].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[0].addr = g_mcp794xx.addr;
msg[0].flags = 0;
msg[0].buffer = buffer;
msg[0].length = 2;
ret = I2C_TRANSFER(g_mcp794xx.i2c, msg, 1);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
/* Verify that the oscillator is running. */
wkdayaddr = MCP794XX_REG_RTCWKDAY;
msg[0].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[0].addr = g_mcp794xx.addr;
msg[0].flags = I2C_M_NOSTOP;
msg[0].buffer = &wkdayaddr;
msg[0].length = 1;
msg[1].frequency = CONFIG_MCP794XX_I2C_FREQUENCY;
msg[1].addr = g_mcp794xx.addr;
msg[1].flags = I2C_M_READ;
msg[1].buffer = &wkday;
msg[1].length = 1;
retries = MCP794XX_OSCRUN_READ_RETRY;
do
{
/* Give time to oscillator to change its status */
nxsig_usleep(10000);
ret = I2C_TRANSFER(g_mcp794xx.i2c, msg, 2);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
retries--;
}
while ((wkday & MCP794XX_RTCWKDAY_OSCRUN) == 0 && retries > 0);
return OK;
}
#endif /* CONFIG_RTC_MCP794XX */
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