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arch/arm/src/am335x/am335x_sysclk.c: Add a function to return a frequency of the system clock.

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This commit is contained in:
Gregory Nutt 2019-07-08 14:08:26 -06:00
parent ed91fa34a0
commit e16c73957d
3 changed files with 162 additions and 0 deletions
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1
arch/arm/src/am335x/Make.defs
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@ -126,6 +126,7 @@ CHIP_ASRCS =
CHIP_CSRCS = am335x_boot.c am335x_clockconfig.c am335x_pinmux.c am335x_irq.c
CHIP_CSRCS += am335x_gpio.c am335x_lowputc.c am335x_serial.c am335x_wdog.c
CHIP_CSRCS += am335x_sysclk.c
ifneq ($(CONFIG_SCHED_TICKLESS),y)
CHIP_CSRCS += am335x_timerisr.c

102
arch/arm/src/am335x/am335x_sysclk.c Normal file
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@ -0,0 +1,102 @@
/****************************************************************************
* arch/arm/src/am335x/am335x_sysclk.c
*
* Copyright (C) 2019 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <nuttx/config.h>
#include <stdint.h>
#include <errno.h>
#include "up_arch.h"
#include "hardware/am335x_memorymap.h"
#include "am335x_sysclk.h"
/****************************************************************************
* Pre-processor definitions
****************************************************************************/
/* REVISIT: These belong in a control module register header file */
#define AM335X_SCM_CTRL_STATUS_OFFSET 0x40
#define AM335X_SCM_CTRL_STATUS (AM335X_CONTROL_MODULE_VADDR + AM335X_SCM_CTRL_STATUS_OFFSET)
#define SCM_CTRL_STATUS_SYSBOOT1_SHIFT (22) /* Bits 22-23: Crystal clock frequency selection */
#define SCM_CTRL_STATUS_SYSBOOT1_MASK (3 << SCM_CTRL_STATUS_SYSBOOT1_SHIFT)
# define SCM_CTRL_STATUS_SYSBOOT1_19p2MHZ (0 << SCM_CTRL_STATUS_SYSBOOT1_SHIFT)
# define SCM_CTRL_STATUS_SYSBOOT1_24MHZ (1 << SCM_CTRL_STATUS_SYSBOOT1_SHIFT)
# define SCM_CTRL_STATUS_SYSBOOT1_25MHZ (2 << SCM_CTRL_STATUS_SYSBOOT1_SHIFT)
# define SCM_CTRL_STATUS_SYSBOOT1_26MHZ (3 << SCM_CTRL_STATUS_SYSBOOT1_SHIFT)
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: am335x_get_sysclk
*
* Description:
* Return the sysclk frequency
*
****************************************************************************/
int32_t am335x_get_sysclk(void)
{
uint32_t regval;
/* Read the input clock freq from the control module. */
regval = getreg32(AM335X_SCM_CTRL_STATUS);
/* Return the frequency of the configured crystal */
switch (regval & SCM_CTRL_STATUS_SYSBOOT1_MASK)
{
case SCM_CTRL_STATUS_SYSBOOT1_19p2MHZ: /* 19.2Mhz */
return 19200000;
case SCM_CTRL_STATUS_SYSBOOT1_24MHZ: /* 24Mhz */
return 24000000;
case SCM_CTRL_STATUS_SYSBOOT1_25MHZ: /* 25Mhz */
return 25000000;
case SCM_CTRL_STATUS_SYSBOOT1_26MHZ: /* 26Mhz */
return 26000000;
}
return -EINVAL; /* Should never happen */
}

59
arch/arm/src/am335x/am335x_sysclk.h Normal file
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@ -0,0 +1,59 @@
/****************************************************************************
* arch/arm/src/am335x/am335x_sysclk.h
*
* Copyright (C) 2019 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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.
*
****************************************************************************/
#ifndef __ARCH_ARM_SRC_AM335X_AM335X_SYSCLK_H
#define __ARCH_ARM_SRC_AM335X_AM335X_SYSCLK_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <stdint.h>
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/****************************************************************************
* Name: am335x_get_sysclk
*
* Description:
* Return the sysclk frequency
*
****************************************************************************/
int32_t am335x_get_sysclk(void);
#endif /* __ARCH_ARM_SRC_AM335X_AM335X_SYSCLK_H */