From 5405817a6e7a6538c4bcb1c3076ddc83fe5d03f9 Mon Sep 17 00:00:00 2001
From: Chin Liang See <clsee@altera.com>
Date: Sun, 7 Aug 2016 22:50:40 +0800
Subject: [PATCH] spi: cadence_qspi_apb: Ensure baudrate doesn't exceed max
 value

Ensuring the baudrate divisor value doesn't exceed the max value
in the calculation.It will be capped at max value to ensure the
correct value being written into the register.

Example of the existing bug is when calculated div = 16. After and
with the mask, the value written to register is actually 0 (register
field for baudrate divisor). With this fix, the value written is now
15 which is max value for baudrate divisor.

Signed-off-by: Chin Liang See <clsee@altera.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Jagan Teki <jteki@openedev.com>
Cc: Dinh Nguyen <dinguyen@altera.com>
---
 drivers/spi/cadence_qspi_apb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/cadence_qspi_apb.c b/drivers/spi/cadence_qspi_apb.c
index 1a35d558a6..1d68379c93 100644
--- a/drivers/spi/cadence_qspi_apb.c
+++ b/drivers/spi/cadence_qspi_apb.c
@@ -293,8 +293,11 @@ void cadence_qspi_apb_config_baudrate_div(void *reg_base,
 	debug("%s: ref_clk %dHz sclk %dHz Div 0x%x\n", __func__,
 	      ref_clk_hz, sclk_hz, div);
 
-	div = (div & CQSPI_REG_CONFIG_BAUD_MASK) << CQSPI_REG_CONFIG_BAUD_LSB;
-	reg |= div;
+	/* ensure the baud rate doesn't exceed the max value */
+	if (div > CQSPI_REG_CONFIG_BAUD_MASK)
+		div = CQSPI_REG_CONFIG_BAUD_MASK;
+
+	reg |= (div << CQSPI_REG_CONFIG_BAUD_LSB);
 	writel(reg, reg_base + CQSPI_REG_CONFIG);
 
 	cadence_qspi_apb_controller_enable(reg_base);
-- 
2.39.5