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/***************************************************************************
* z16f/z16f_clkinit.c
*
* Copyright (C) 2008-2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Based upon sample code included with the Zilog ZDS-II toolchain.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
***************************************************************************/
/***************************************************************************
* Included Files
***************************************************************************/
#include "chip/chip.h"
/***************************************************************************
* Definitions
***************************************************************************/
/* System clock source value from ZDS target settings */
extern _Erom unsigned long SYS_CLK_SRC;
#define _DEFSRC ((unsigned long)&SYS_CLK_SRC)
/* System clock frequency value from ZDS target settings */
extern _Erom unsigned long SYS_CLK_FREQ;
#define _DEFCLK ((unsigned long)&SYS_CLK_FREQ)
/***************************************************************************
* Private Functions
***************************************************************************/
#ifdef CONFIG_DEBUG
/***************************************************************************
* System clock initialization--DEBUG. Code Using Frequency Input from
* ZDS IDE.
*
* The sysclk_init function below uses the flexibility of the ZDS debug
* environment to allow the user to experiment with different clock frequency
* settings to help determine the frequency requirements of his Project. The
* function allows the selection of internal 5.56 MHz, the 10 KHz Watch Dog
* timer or an external clock Source. ZNEO supports clock frequency division
* with the Clock Division Register. The clock division Register will divide
* by (a minimum of) 2 or more. An assumed clock value of 5.5 MHz internal or
* an external clock of 20 MHz was used as the crystal frequency to match the
* Demo Target. The User can enter a new frequency in the OTHER clock dialog
* Target Setting. The clock frequency is passed with the variable _DEFFREQ
* and the clock source is _DEFSRC.
*
* NOTE: The UART output is designed to work with 5.56 MHz internal and 20 MHz
* External clock frequencies at the Default Baud rate of 57.6K Baud.
* Entering different clock frequencies may cause the UART to stop transmitting
* unless the user makes changes to the UART routines.
*
* Function Not Recommended for Release Code.
*
***************************************************************************/
static void z16f_sysclkinit(int clockid, uint32_t frequency)
{
int count;
int temp_oscdiv;
/* _DEFSRC (SCKSEL Bits 1,0) is passed to program view the .linkcmd file */
if ((getreg8(Z16F_OSC_CTL) & 0x03) != clockid)
{
switch (clockid)
{
/* 0: Internal precision oscillator functions as system clock at 5.6 MHz */
case 0:
{
/* Enable 5.6 MHz clock RESET DEFAULT*/
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xa0, Z16F_OSC_CTL);
/* Wait for oscillator to stabilize */
for (count = 0; count < 10000; count++);
/* Select 5.6 MHz clock (SCKSEL=0) */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xa0, Z16F_OSC_CTL);
}
break;
/* 1: Crystal oscillator or external clock driver functions as system clock */
case 1:
{
/* No divider for the oscillator */
putreg8(0x00, Z16F_OSC_DIV);
/* Enable external oscillator */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xe0, Z16F_OSC_CTL); /* INTEN+XTLEN+WDTEN */
/* Wait for oscillator to stabilize */
for (count = 0; count < 10000; count++);
/* select external oscillator (SCKSEL=2) */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xe0 | 1, Z16F_OSC_CTL);
}
break;
/* 2: Reserved */
default:
case 2:
{
/* Reserved */
}
break;
/* Watchdog Timer oscillator functions as system clock. */
case 3:
{
/* Enable watchdog timer clock */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xb0, Z16F_OSC_CTL);
/* Wait for oscillator to stabilize */
for (count = 0; count < 10000; count++);
/* Select watch dog timer clock (SKCSEL=3) */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xb0 | 3, Z16F_OSC_CTL);
}
break;
}
}
/* Check SysClock Frequency.
* divide the clock if the user has selected the OTHER option for frequency.
*/
if (((clockid == 0) && (frequency < 3000000ul)) ||
((clockid == 1) && (frequency <= 10000000ul)))
{
if ( clockid == 0 )
{
temp_oscdiv = (5526000ul / (frequency + 1));
/* Example @ 32 KHz: 0xAC (172 decimal)*/
}
else
{
temp_oscdiv = ((20000000ul / (frequency +1)) + 1);
}
/* Unlock and Set the Oscillator Division Register (Z16F_OSC_DIV) */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(temp_oscdiv, Z16F_OSC_DIV);
}
/* Wait for oscillator to stabilize */
for (count = 0; count < 10000; count++);
}
#else /* CONFIG_DEBUG */
/***************************************************************************
* System Clock Initialization Recommended for Release Code
*
* The z16f_sysclkinit function below allows the user to switch from
* Internal to External Clock source and should be used for clock frequency
* switching to the External Clock. Note the delay to allow the clock to
* stabilize.
***************************************************************************/
static void z16f_sysclkinit(int clockid, uint32_t frequency)
{
int count;
/* In this configuration, we support only the external oscillator/clock
* the the source of the system clock (__DEFCLK is ignored).
*/
if ((getreg8(Z16F_OSC_CTL) & 0x03) != 1)
{
/* No divider for the oscillator */
putreg8(0x00, Z16F_OSC_DIV);
/* Enable external oscillator */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xe0, Z16F_OSC_CTL); /* INTEN+XTLEN+WDTEN */
/* Wait for oscillator to stabilize */
for (count = 0; count < 10000; count++);
/* Select external oscillator (SCLKSEL=1) */
putreg8(0xe7, Z16F_OSC_CTL); /* Unlock the crystal oscillator */
putreg8(0x18, Z16F_OSC_CTL);
putreg8(0xe0 | 1, Z16F_OSC_CTL); /* Use the external osc/clock as system clock */
}
}
#endif /* CONFIG_DEBUG */
/***************************************************************************
* Public Functions
***************************************************************************/
/***************************************************************************
* Name: z16f_clkinit
***************************************************************************/
void z16f_clkinit(void)
{
/* _DEFSRC (SCKSEL Bits 1,0) is passed to program view the .linkcmd file */
z16f_sysclkinit(_DEFSRC, _DEFCLK);
}
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