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Subject[PATCH] spi: cadence-quadspi: Add upper limit safety check to baudrate divisor
Date
While bringing up the cadence-quadspi driver on a customer board,
I discovered that the baud divisor calculation can exceed the
peripheral's maximum in some circumstances. This will prevent it.

Signed-off-by: Nathan Barrett-Morrison <nathan.morrison@timesys.com>
---
drivers/spi/spi-cadence-quadspi.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 447230547945..250575fb7b0e 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -1119,6 +1119,10 @@ static void cqspi_config_baudrate_div(struct cqspi_st *cqspi)
/* Recalculate the baudrate divisor based on QSPI specification. */
div = DIV_ROUND_UP(ref_clk_hz, 2 * cqspi->sclk) - 1;

+ /* Maximum baud divisor */
+ if (div > CQSPI_REG_CONFIG_BAUD_MASK)
+ div = CQSPI_REG_CONFIG_BAUD_MASK;
+
reg = readl(reg_base + CQSPI_REG_CONFIG);
reg &= ~(CQSPI_REG_CONFIG_BAUD_MASK << CQSPI_REG_CONFIG_BAUD_LSB);
reg |= (div & CQSPI_REG_CONFIG_BAUD_MASK) << CQSPI_REG_CONFIG_BAUD_LSB;
--
2.30.2
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