With serdev device support added there's now a corner case where:
1. There is a DT node for a serdev device on one of the UARTs
2. There is no driver that binds against serdev device's compatibility
string
with 1 and 2 being true it is possible to end up in a situation where
a particualr UART has not been initalized to any baudrate when
clock_notifier_call_chain() gets called. This effectively translates
to
set_baudrate(uart, 0);
which for LPUART driver result in a division by zero.
To avoid this problem, convert lpuart_serial_setbaudrate() to treat
zero baudrate as a request to disable the UART. While we are at it add
a BUG_ON() to lpuart_setbrg() to simplify finding any future bugs.
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
drivers/serial/serial_lpuart.c | 13 ++++++++-----
include/serial/lpuart.h | 2 ++
2 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
index f28035a32..246fc3d3a 100644
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -68,11 +68,14 @@ static int lpuart_serial_setbaudrate(struct console_device *cdev,
lpuart_enable(lpuart, false);
- lpuart_setbrg(lpuart->base,
- clk_get_rate(lpuart->clk),
- baudrate);
-
- lpuart_enable(lpuart, true);
+ /*
+ * We treat baudrate of 0 as a request to disable UART
+ */
+ if (baudrate) {
+ lpuart_setbrg(lpuart->base, clk_get_rate(lpuart->clk),
+ baudrate);
+ lpuart_enable(lpuart, true);
+ }
lpuart->baudrate = baudrate;
diff --git a/include/serial/lpuart.h b/include/serial/lpuart.h
index a920291de..9c6e271eb 100644
--- a/include/serial/lpuart.h
+++ b/include/serial/lpuart.h
@@ -228,6 +228,8 @@ static inline void lpuart_setbrg(void __iomem *base,
unsigned int bfra;
u16 sbr;
+ BUG_ON(!baudrate);
+
sbr = (u16) (refclock / (16 * baudrate));
writeb(sbr >> 8, base + UARTBDH);
--
2.17.0
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