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nuttx/arch/arm/src/samd2l2/sam_sercom.c
Fotis Panagiotopoulos bbf3f2866d Fixed non-UTF8 characters.
2022-09-28 09:38:55 +08:00

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/****************************************************************************
* arch/arm/src/samd2l2/sam_sercom.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.
*
****************************************************************************/
/* References:
* 1. "Atmel SAM D20J / SAM D20G / SAM D20E ARM-Based Microcontroller
* Datasheet", 42129J-SAM-12/2013
*/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>
#include "arm_internal.h"
#include "sam_config.h"
#include "sam_pm.h"
#include "sam_gclk.h"
#include "sam_sercom.h"
#include <arch/board/board.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#undef HAVE_SERCOM0_4
#if defined(CONFIG_SAMD2L2_SERCOM0) || defined(CONFIG_SAMD2L2_SERCOM1) || \
defined(CONFIG_SAMD2L2_SERCOM2) || defined(CONFIG_SAMD2L2_SERCOM3) || \
defined(CONFIG_SAMD2L2_SERCOM4)
# define HAVE_SERCOM0_4
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sercom_coreclk_configure
*
* Description:
* Configure the SERCOM core source clock.
*
* Two generic clocks are used by the SERCOM: GCLK_SERCOMx_CORE and
* GCLK_SERCOM_SLOW. The core clock (GCLK_SERCOMx_CORE) is required to
* clock the SERCOM while operating as a master, while the slow clock
* (GCLK_SERCOM_SLOW) is only required for certain functions. SERCOM
* modules must share the same slow GCLK channel ID.
*
* The baud-rate generator runs off the GCLK_SERCOMx_CORE clock (or,
* optionally, external clock).
*
****************************************************************************/
#if defined(CONFIG_ARCH_FAMILY_SAMD20) || defined(CONFIG_ARCH_FAMILY_SAMD21)
void sercom_coreclk_configure(int sercom, int gclkgen, bool wrlock)
{
uint16_t regval;
uint8_t gclkcore;
/* Set up the SERCOMN_GCLK_ID_CORE clock */
gclkcore = (uint8_t)SERCOM_GCLK_ID_CORE(sercom);
regval = ((uint16_t)gclkcore << GCLK_CLKCTRL_ID_SHIFT);
/* Select and disable the SERCOMN_GCLK_ID_CORE generic clock */
putreg16(regval, SAM_GCLK_CLKCTRL);
/* Wait for clock to become disabled */
while ((getreg16(SAM_GCLK_CLKCTRL) & GCLK_CLKCTRL_CLKEN) != 0);
/* Select the SERCOMN_GCLK_ID_CORE source clock generator */
regval |= (uint16_t)gclkgen << GCLK_CLKCTRL_GEN_SHIFT;
/* Write the new configuration */
putreg16(regval, SAM_GCLK_CLKCTRL);
/* Enable the SERCOMN_GCLK_ID_CORE generic clock, optionally locking
* further writes to this GCLK.
*/
regval |= GCLK_CLKCTRL_CLKEN;
if (wrlock)
{
regval |= GCLK_CLKCTRL_WRTLOCK;
}
putreg16(regval, SAM_GCLK_CLKCTRL);
}
#endif
/****************************************************************************
* Name: sercom_slowclk_configure
*
* Description:
* Configure the SERCOM slow source clock.
*
* Two generic clocks are used by the SERCOM: GCLK_SERCOMx_CORE and
* GCLK_SERCOM_SLOW. The core clock (GCLK_SERCOMx_CORE) is required to
* clock the SERCOM while operating as a master, while the slow clock
* (GCLK_SERCOM_SLOW) is only required for certain functions. SERCOM
* modules must share the same slow GCLK channel ID.
*
****************************************************************************/
void sercom_slowclk_configure(int sercom, int gclkgen)
{
#if defined(CONFIG_ARCH_FAMILY_SAML21)
#ifdef HAVE_SERCOM0_4
static bool configured = false;
#endif
#ifdef CONFIG_SAMD2L2_SERCOM5
static bool configured5 = false;
#endif
#ifdef CONFIG_DEBUG_ASSERTIONS
#ifdef HAVE_SERCOM0_4
static uint8_t slowgen04 = 0xff;
#endif
#ifdef CONFIG_SAMD2L2_SERCOM5
static uint8_t slowgen5 = 0xff;
#endif
#endif
/* Setup the SERCOMN_GCLK channel. SERCOM0-4 use a common channel, but
* SERCOM5 uses a different channel. Configuration should be done only
* once.
*/
switch (sercom)
{
#ifdef HAVE_SERCOM0_4
#ifdef CONFIG_SAMD2L2_SERCOM0
case 0:
#endif
#ifdef CONFIG_SAMD2L2_SERCOM1
case 1:
#endif
#ifdef CONFIG_SAMD2L2_SERCOM2
case 2:
#endif
#ifdef CONFIG_SAMD2L2_SERCOM3
case 3:
#endif
#ifdef CONFIG_SAMD2L2_SERCOM4
case 4:
#endif
if (!configured)
{
/* Configure the common slow clock channel */
sam_gclk_chan_enable(GCLK_CHAN_SERCOM0_SLOW, gclkgen);
/* The slow clock is now configured and should not be configured
* again.
*/
configured = true;
#ifdef CONFIG_DEBUG_ASSERTIONS
slowgen04 = (uint8_t)gclkgen;
#endif
}
#ifdef CONFIG_DEBUG_ASSERTIONS
/* Already configured. This is okay provided that the same GCLK
* generator is being used. Otherwise, there is a problem.
*/
else
{
DEBUGASSERT((int)slowgen04 == gclkgen);
}
#endif
break;
#endif /* HAVE_SERCOM0_4 */
#ifdef CONFIG_SAMD2L2_SERCOM5
case 5:
if (!configured5)
{
/* Configure the common slow clock channel */
sam_gclk_chan_enable(GCLK_CHAN_SERCOM5_SLOW, gclkgen);
/* The slow clock is now configured and should not be configured
* again.
*/
configured5 = true;
#ifdef CONFIG_DEBUG_ASSERTIONS
slowgen5 = (uint8_t)gclkgen;
#endif
}
#ifdef CONFIG_DEBUG_ASSERTIONS
/* Already configured. This is okay provided that the same GCLK
* generator is being used. Otherwise, there is a problem.
*/
else
{
DEBUGASSERT((int)slowgen5 == gclkgen);
}
#endif
break;
#endif /* CONFIG_SAMD2L2_SERCOM5 */
/* Unsupported or invalid SERCOM number provided */
default:
DEBUGPANIC();
break;
}
#elif defined(CONFIG_ARCH_FAMILY_SAMD20) || defined(CONFIG_ARCH_FAMILY_SAMD21)
static bool configured = false;
uint16_t regval;
/* Since GCLK_SERCOM_SLOW is shared amongst all SERCOM modules, it should
* only be configured one time.
*/
if (!configured)
{
/* Set up the SERCOM_GCLK_ID_SLOW clock */
regval = (SERCOM_GCLK_ID_SLOW << GCLK_CLKCTRL_ID_SHIFT);
/* Select and disable the SERCOM_GCLK_ID_SLOW generic clock */
putreg16(regval, SAM_GCLK_CLKCTRL);
/* Wait for clock to become disabled */
while ((getreg16(SAM_GCLK_CLKCTRL) & GCLK_CLKCTRL_CLKEN) != 0);
/* Select the SERCOM_GCLK_ID_SLOW clock source generator */
regval |= (uint16_t)gclkgen << GCLK_CLKCTRL_GEN_SHIFT;
/* Write the new configuration */
putreg16(regval, SAM_GCLK_CLKCTRL);
/* Enable the GCLK_SERCOM_SLOW generic clock and lock further
* writes to this GCLK. When this bit is written, it will lock
* further writes to the generic clock pointed by the CLKCTRL.ID. The
* generic clock generator pointed by CLKCTRL.GEN and the GENDIV.DIV
* will also be locked.
*
* We lock the SERCOM slow clock because it is common to all SERCOM
* modules and, once set, should not be changed again.
*/
regval |= (/* GCLK_CLKCTRL_WRTLOCK | */ GCLK_CLKCTRL_CLKEN);
putreg16(regval, SAM_GCLK_CLKCTRL);
/* Now we are configured */
configured = true;
}
#endif
}
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