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cpu/cc2538/cpu: cleanup clock intialization

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This commit is contained in:
Francisco Molina 2020-03-20 15:29:37 +01:00
parent 7d0c475113
commit 8c35335668
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GPG Key ID: 3E94EAC3DBDEEDA8
2 changed files with 45 additions and 35 deletions
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70
cpu/cc2538/cpu.c
View File

@ -18,23 +18,11 @@
*/
#include <assert.h>
#include "stdio_base.h"
#include "cpu.h"
#include "periph/init.h"
#include "stdio_base.h"
#define BIT(n) ( 1UL << (n) )
/* Select CLOCK_CTRL register bit masks: */
#define OSC32K BIT(24) /**< 32-kHz clock oscillator selection */
#define OSC_PD BIT(17) /**< Oscillator power-down */
#define OSC BIT(16) /**< System clock oscillator selection */
/* CLOCK_CTRL register field offsets: */
#define IO_DIV_SHIFT 8
#define SYS_DIV_SHIFT 0
#define CLOCK_STA_MASK ( OSC32K | OSC )
#include "periph_conf.h"
static void cpu_clock_init(void);
@ -55,22 +43,14 @@ void cpu_init(void)
periph_init();
}
/**
* @brief Configure the controllers clock system
*/
static void cpu_clock_init(void)
{
const uint32_t CLOCK_CTRL_VALUE =
OSC_PD /**< Power down the oscillator not selected by OSC bit (hardware-controlled when selected). */
| (1 << IO_DIV_SHIFT) /**< 16 MHz IO_DIV */
| (1 << SYS_DIV_SHIFT) /**< 16 MHz SYS_DIV */
#if !SYS_CTRL_OSC32K_USE_XTAL
| OSC32K /**< Use internal RC oscillator. */
#endif
;
#if SYS_CTRL_OSC32K_USE_XTAL
/* Set the XOSC32K_Q pads to analog for the external crystal: */
/* set the XOSC32K_Q pads to analog for the external crystal: */
gpio_software_control(GPIO_PD6);
gpio_dir_input(GPIO_PD6);
IOC_PXX_OVER[GPIO_PD6] = IOC_OVERRIDE_ANA;
@ -80,15 +60,41 @@ static void cpu_clock_init(void)
IOC_PXX_OVER[GPIO_PD7] = IOC_OVERRIDE_ANA;
#endif
/* Configure the clock settings: */
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRL = CLOCK_CTRL_VALUE;
/* Wait for the new clock settings to take effect: */
while ((SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STA ^ CLOCK_CTRL_VALUE) & CLOCK_STA_MASK);
/* CLOCK_CTRL.OSC32K register bit can be written at any time, but only takes
effect when 16MHz RCOSC is the active system clock source, 16MHz RCOSC is
the active clock on reset but to be idempotent make sure it's the
selected source clock */
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.OSC = 1;
while (SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SOURCE_CHANGE) {}
#if SYS_CTRL_OSC32K_USE_XTAL
/* Wait for the 32-kHz crystal oscillator to stabilize: */
while ( SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SYNC_32K);
while (!SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SYNC_32K);
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.OSC32K = 0;
while (SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.OSC32K) {}
#else
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.OSC32K = 1;
while (!SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.OSC32K) {}
#endif
#if SYS_CTRL_OSC_USE_XTAL
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.OSC = 0;
#else
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.OSC = 1;
#endif
/* power down the oscillator not selected by OSC bit */
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.OSC_PD = 1;
/* set desired system clock rate */
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.SYS_DIV = \
__builtin_ctz(XOSC32M_FREQ / CLOCK_CORECLOCK);
/* set desired I/O clock rate */
SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRLbits.IO_DIV = \
__builtin_ctz(XOSC32M_FREQ / CLOCK_IO);
/* wait for new clock settings to take effect */
while (SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SOURCE_CHANGE) {}
#if SYS_CTRL_OSC32K_USE_XTAL
/* 32-kHz crystal oscillator to stabilize after a positive transition */
while (SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SYNC_32K) {}
while (!SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SYNC_32K) {}
#endif
}

10
cpu/cc2538/include/cc2538.h
View File

@ -798,10 +798,14 @@ typedef volatile uint32_t cc2538_reg_t; /**< Least-significant 32 bits of the IE
#define CCTEST_USBCTRL ( *(cc2538_reg_t*)0x44010050 ) /**< CCTEST USB PHY stand-by control */
/** @} */
#define XOSC32M_FREQ 32000000 /**< 32 MHz external oscillator/clock frequency */
#define RCOSC16M_FREQ 16000000 /**< 16 MHz internal RC oscillator frequency */
#define XOSC32M_FREQ 32000000U /**< 32 MHz external oscillator/clock frequency */
#define RCOSC16M_FREQ 16000000U /**< 16 MHz internal RC oscillator frequency */
#define CC2538_VTOR_ALIGN 512 /**< CC2538 Vector Table alignment */
#define XOSC32K_FREQ 32768U /**< 32 KHz external oscillator/clock frequency */
#define RCOSC32K_FREQ 32753U /**< 32 KHz internal RC oscillator frequency */
#define CC2538_VTOR_ALIGN 512 /**< CC2538 Vector Table alignment */
#ifdef __cplusplus
}