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SubjectRe: [PATCH 1/3] serial/imx: add device tree support
Hi Grant,

I just gave a try to use aliases node for identify the device index.
Please take a look and let me know if it's what you expect.

On Sun, Jun 19, 2011 at 03:30:02PM +0800, Shawn Guo wrote:
[...]
> > >
> > > +#ifdef CONFIG_OF
> > > +static int serial_imx_probe_dt(struct imx_port *sport,
> > > + struct platform_device *pdev)
> > > +{
> > > + struct device_node *node = pdev->dev.of_node;
> > > + const __be32 *line;
> > > +
> > > + if (!node)
> > > + return -ENODEV;
> > > +
> > > + line = of_get_property(node, "id", NULL);
> > > + if (!line)
> > > + return -ENODEV;
> > > +
> > > + sport->port.line = be32_to_cpup(line) - 1;
> >
> > Hmmm, I really would like to be rid of this. Instead, if uarts must
> > be enumerated, the driver should look for a /aliases/uart* property
> > that matches the of_node. Doing it that way is already established in
> > the OpenFirmware documentation, and it ensures there are no overlaps
> > in the global namespace.
> >
>
> I just gave one more try to avoid using 'aliases', and you gave a
> 'no' again. Now, I know how hard you are on this. Okay, I start
> thinking about your suggestion seriously :)
>
> > We do need some infrastructure to make that easier though. Would you
> > have time to help put that together?
> >
> Ok, I will give it a try.
>

diff --git a/arch/arm/boot/dts/imx51-babbage.dts b/arch/arm/boot/dts/imx51-babbage.dts
index da0381a..f4a5c3c 100644
--- a/arch/arm/boot/dts/imx51-babbage.dts
+++ b/arch/arm/boot/dts/imx51-babbage.dts
@@ -18,6 +18,12 @@
compatible = "fsl,imx51-babbage", "fsl,imx51";
interrupt-parent = <&tzic>;

+ aliases {
+ serial0 = &uart0;
+ serial1 = &uart1;
+ serial2 = &uart2;
+ };
+
chosen {
bootargs = "console=ttymxc0,115200 root=/dev/mmcblk0p3 rootwait";
};
@@ -47,29 +53,29 @@
reg = <0x70000000 0x40000>;
ranges;

- uart@7000c000 {
+ uart2: uart@7000c000 {
compatible = "fsl,imx51-uart", "fsl,imx21-uart";
reg = <0x7000c000 0x4000>;
interrupts = <33>;
id = <3>;
- fsl,has-rts-cts;
+ fsl,uart-has-rtscts;
};
};

- uart@73fbc000 {
+ uart0: uart@73fbc000 {
compatible = "fsl,imx51-uart", "fsl,imx21-uart";
reg = <0x73fbc000 0x4000>;
interrupts = <31>;
id = <1>;
- fsl,has-rts-cts;
+ fsl,uart-has-rtscts;
};

- uart@73fc0000 {
+ uart1: uart@73fc0000 {
compatible = "fsl,imx51-uart", "fsl,imx21-uart";
reg = <0x73fc0000 0x4000>;
interrupts = <32>;
id = <2>;
- fsl,has-rts-cts;
+ fsl,uart-has-rtscts;
};
};

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 632ebae..13df5d2 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -737,6 +737,37 @@ err0:
EXPORT_SYMBOL(of_parse_phandles_with_args);

/**
+ * of_get_device_index - Get device index by looking up "aliases" node
+ * @np: Pointer to device node that asks for device index
+ * @name: The device alias without index number
+ *
+ * Returns the device index if find it, else returns -ENODEV.
+ */
+int of_get_device_index(struct device_node *np, const char *alias)
+{
+ struct device_node *aliases = of_find_node_by_name(NULL, "aliases");
+ struct property *prop;
+ char name[32];
+ int index = 0;
+
+ if (!aliases)
+ return -ENODEV;
+
+ while (1) {
+ snprintf(name, sizeof(name), "%s%d", alias, index);
+ prop = of_find_property(aliases, name, NULL);
+ if (!prop)
+ return -ENODEV;
+ if (np == of_find_node_by_path(prop->value))
+ break;
+ index++;
+ }
+
+ return index;
+}
+EXPORT_SYMBOL(of_get_device_index);
+
+/**
* prom_add_property - Add a property to a node
*/
int prom_add_property(struct device_node *np, struct property *prop)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index da436e0..852668f 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1271,18 +1271,18 @@ static int serial_imx_probe_dt(struct imx_port *sport,
struct device_node *node = pdev->dev.of_node;
const struct of_device_id *of_id =
of_match_device(imx_uart_dt_ids, &pdev->dev);
- const __be32 *line;
+ int line;

if (!node)
return -ENODEV;

- line = of_get_property(node, "id", NULL);
- if (!line)
+ line = of_get_device_index(node, "serial");
+ if (IS_ERR_VALUE(line))
return -ENODEV;

- sport->port.line = be32_to_cpup(line) - 1;
+ sport->port.line = line;

- if (of_get_property(node, "fsl,has-rts-cts", NULL))
+ if (of_get_property(node, "fsl,uart-has-rtscts", NULL))
sport->have_rtscts = 1;

if (of_get_property(node, "fsl,irda-mode", NULL))
diff --git a/include/linux/of.h b/include/linux/of.h
index bfc0ed1..3153752 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -213,6 +213,8 @@ extern int of_parse_phandles_with_args(struct device_node *np,
const char *list_name, const char *cells_name, int index,
struct device_node **out_node, const void **out_args);

+extern int of_get_device_index(struct device_node *np, const char *alias);
+
extern int of_machine_is_compatible(const char *compat);

extern int prom_add_property(struct device_node* np, struct property* prop);
--
Regards,
Shawn



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