56471c77b3
Gregory Nutt has submitted the SGA and we can migrate the licenses to Apache. Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
126 lines
3.9 KiB
C
126 lines
3.9 KiB
C
/****************************************************************************
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* arch/arm/src/samv7/sam_hsmci_clkdiv.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/* References:
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* SAMV7D3 Series Data Sheet
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*/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <arch/board/board.h>
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#include "chip.h"
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#include "hardware/sam_hsmci.h"
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#include "sam_hsmci.h"
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#ifdef CONFIG_SAMV7_HSMCI0
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sam_hsmci_clkdiv
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*
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* Description:
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* Multimedia Card Interface clock (MCCK or MCI_CK) is Master Clock (MCK)
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* divided by (2*(CLKDIV) + CLOCKODD + 2).
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*
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* CLKFULLDIV = 2*CLKDIV + CLOCKODD;
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* MCI_SPEED = MCK / (CLKFULLDIV + 2)
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* CLKFULLDIV = MCK / MCI_SPEED - 2
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*
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* CLKDIV = CLKFULLDIV >> 1
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* CLOCKODD = CLKFULLDIV & 1
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*
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* Where CLKDIV has a range of 0-255.
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*
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* NOTE: The primary use of this function is for cases where the clock
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* frequencies are not known a priori and so HSMCI clock dividers must
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* be determined dynamically. This is the case, for example, when we
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* execute out of SDRAM. In that case, the clocking was set up by the
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* bootloader that brought us into SDRAM and it is that bootloader that
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* has configured the clocking.
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*
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* Input Parameters:
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* target - The target SD frequency
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*
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* Returned Value:
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* A bitset containing the CLKDIV and CLKODD bits as needed to configure
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* the HSMCI clock output.
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*
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****************************************************************************/
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uint32_t sam_hsmci_clkdiv(uint32_t target)
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{
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uint32_t clkfulldiv;
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uint32_t ret;
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/* Get the largest divisor does not exceed the target value */
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clkfulldiv = (BOARD_MCK_FREQUENCY + target - 1) / target;
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if (clkfulldiv > 2)
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{
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clkfulldiv -= 2;
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}
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else
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{
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clkfulldiv = 0;
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}
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if (clkfulldiv > 511)
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{
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clkfulldiv = 511;
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}
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ret = (clkfulldiv >> 1) << HSMCI_MR_CLKDIV_SHIFT;
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if ((clkfulldiv & 1) != 0)
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{
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ret |= HSMCI_MR_CLKODD;
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}
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return ret;
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}
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#endif /* CONFIG_SAMV7_HSMCI */
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