summaryrefslogtreecommitdiff
path: root/drivers/tty
diff options
context:
space:
mode:
authorDaniel Thompson <daniel.thompson@linaro.org>2014-09-09 14:03:57 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-10 17:59:41 +0400
commit08177ece596ccc9b9c194542c095c863c101fd11 (patch)
treeb99406de5a0040610501496f2e26ddb7789fcb59 /drivers/tty
parentefb089517d2f34a58aceb600ab58b0ca3db1fa07 (diff)
downloadlinux-08177ece596ccc9b9c194542c095c863c101fd11.tar.xz
serial: asc: Adopt readl_/writel_relaxed()
The architectures supported by this driver, arm and sh, have expensive implementations of writel(), reliant on spin locks and explicit L2 cache management. These architectures provide a cheaper writel_relaxed() which is much better suited to peripherals that do not perform DMA. The situation with readl()/readl_relaxed()is similar although less acute. This driver does not use DMA and will be more power efficient and more robust (due to absence of spin locks during console I/O) if it uses the relaxed variants. The driver supports COMPILE_TEST and therefore falls back to writel() when writel_relaxed() does not exist. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Srinivas Kandagatla <srinivas.kandagatla@gmail.com> Cc: Maxime Coquelin <maxime.coquelin@st.com> Cc: Patrice Chotard <patrice.chotard@st.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: kernel@stlinux.com Cc: linux-serial@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/st-asc.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index 8b2d7356611d..a3fc1678d2b9 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -151,12 +151,16 @@ static inline struct asc_port *to_asc_port(struct uart_port *port)
static inline u32 asc_in(struct uart_port *port, u32 offset)
{
- return readl(port->membase + offset);
+ return readl_relaxed(port->membase + offset);
}
static inline void asc_out(struct uart_port *port, u32 offset, u32 value)
{
+#ifdef writel_relaxed
+ writel_relaxed(value, port->membase + offset);
+#else
writel(value, port->membase + offset);
+#endif
}
/*