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authorChen-Yu Tsai <wens@csie.org>2014-07-23 23:33:06 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-27 11:07:07 -0700
commit7fe090bf48b522de8cd6fe85e2b3252ed74e74f8 (patch)
treebb5c2994d76becef318ec6e2bfbf125e6603db35
parent1d6ba284dff546baca58e78546da46be3b48462a (diff)
serial: 8250_dw: Add optional reset control support
The Allwinner A31 and A23 SoCs have a reset controller maintaining the UART in reset by default. This patch adds optional reset support to the driver. Signed-off-by: Chen-Yu Tsai <wens@csie.org> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt1
-rw-r--r--drivers/tty/serial/8250/8250_dw.c9
2 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
index 095ac7172ffe..7f76214f728a 100644
--- a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
+++ b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
@@ -15,6 +15,7 @@ The supplying peripheral clock can also be handled, needing a second property
Required elements: "baudclk", "apb_pclk"
Optional properties:
+- resets : phandle to the parent reset controller.
- reg-shift : quantity to shift the register offsets by. If this property is
not present then the register offsets are not shifted.
- reg-io-width : the size (in bytes) of the IO accesses that should be
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index affdcb192aed..501db2f58fd2 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -26,6 +26,7 @@
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/clk.h>
+#include <linux/reset.h>
#include <linux/pm_runtime.h>
#include <asm/byteorder.h>
@@ -60,6 +61,7 @@ struct dw8250_data {
int line;
struct clk *clk;
struct clk *pclk;
+ struct reset_control *rst;
struct uart_8250_dma dma;
};
@@ -383,6 +385,10 @@ static int dw8250_probe(struct platform_device *pdev)
}
}
+ data->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
+ if (!IS_ERR(data->rst))
+ reset_control_deassert(data->rst);
+
data->dma.rx_chan_id = -1;
data->dma.tx_chan_id = -1;
data->dma.rx_param = data;
@@ -426,6 +432,9 @@ static int dw8250_remove(struct platform_device *pdev)
serial8250_unregister_port(data->line);
+ if (!IS_ERR(data->rst))
+ reset_control_assert(data->rst);
+
if (!IS_ERR(data->pclk))
clk_disable_unprepare(data->pclk);

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