141 lines
4.7 KiB
C
141 lines
4.7 KiB
C
/****************************************************************************
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* arch/arm/src/samv7/sam_pmc.c
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*
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* Copyright (C) 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* References:
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*
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* SAMV7D3 Series Data Sheet
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may
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* be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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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 "chip/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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