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SAMV71 QSPI: Fix frequency calculation. Need to use ceil() type logic so that requested frequency is not exceeded

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This commit is contained in:
Gregory Nutt 2015-08-31 10:18:17 -06:00
parent 4f87a71e6d
commit 9ba349f2b8
1 changed files with 8 additions and 4 deletions
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12
arch/arm/src/samv7/sam_qspi.c
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@ -1094,10 +1094,12 @@ static uint32_t qspi_setfrequency(struct qspi_dev_s *dev, uint32_t frequency)
*
* QSCK frequency = QSPI_CLK / SCBR, or SCBR = QSPI_CLK / frequency
*
* Where SCBR can have the range 1 to 256 and register holds SCBR - 1
* Where SCBR can have the range 1 to 256 and register holds SCBR - 1. NOTE
* that a "ceiling" type of calculation is performed. 'frequency' is treated
* as a not-to-exceed value.
*/
scbr = SAM_QSPI_CLOCK / frequency;
scbr = (frequency + SAM_QSPI_CLOCK - 1) / frequency;
/* Make sure that the divider is within range */
@ -1363,9 +1365,11 @@ static int qspi_command(struct qspi_dev_s *dev,
DEBUGASSERT(cmdinfo->buffer != NULL && cmdinfo->buflen > 0);
/* Make sure that the length is an even multiple of 32-bit words. */
/* Make sure that the length is an even multiple of 32-bit words.
* REVISIT: This could cause access past the end of an allocated
* buffer.
*/
DEBUGASSERT((cmdinfo->buflen & 3) == 0);
buflen = (cmdinfo->buflen + 3) & ~3;
/* Write Instruction Frame Register: