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| author | Andrey Smirnov <andrew.smirnov@gmail.com> | 2018-05-08 14:15:02 -0700 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2018-08-13 09:13:43 +0200 |
| commit | 958f0311136b3e47a1ce3093663f74c4ee139558 (patch) | |
| tree | 148000c4f2f16563bd696d92eec88ee09124da0f | |
| parent | 1df07fbcdfce7852cf97a0397b20b586248e1226 (diff) | |
| download | barebox-958f0311136b3e47a1ce3093663f74c4ee139558.tar.gz barebox-958f0311136b3e47a1ce3093663f74c4ee139558.tar.xz | |
serial: lpuart: Avoid division by zero when requested baudrate is
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@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
| -rw-r--r-- | drivers/serial/serial_lpuart.c | 13 | ||||
| -rw-r--r-- | 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 f28035a326..246fc3d3af 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 a920291dec..9c6e271ebf 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); |