On Tue, Jun 21, 2011 at 1:35 PM, Mitch Bradley [off-list ref] wrote:

What is the problem with

aliases{
? serial0 = "/uart at 7000c000";
}

Properties in the alias node are supposed to have string values.

?

Not sure I follow.  Indeed, properties in the aliases node are string values.

Are you referring to how I was proposing some dtc syntax for
generating the alias strings?

g.

On 6/21/2011 9:13 AM, Grant Likely wrote:

quoted

On Tue, Jun 21, 2011 at 7:55 AM, Shawn Guo[off-list ref]
?wrote:

quoted

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.

Thanks Shawn. ?This is definitely on track. ?Comments below...

quoted

On Sun, Jun 19, 2011 at 03:30:02PM +0800, Shawn Guo wrote:
[...]

quoted

quoted

quoted

+#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 :)

quoted

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;
+ ? ? ? };
+

Hmmm. ?David Gibson had tossed out an idea of automatically generating
aliases from labels. ?It may be time to revisit that idea.

David, perhaps using this format for a label should turn it into an
alias (prefix label with an asterisk):

? ? ? ? *thealias: i2c at 12340000 { /*...*/ };

.... although that approach gets *really* hairy when considering that
different boards will want different enumeration. ?How would one
override an automatic alias defined by an included .dts file?

quoted

? ? ? ?chosen {
? ? ? ? ? ? ? ?bootargs = "console=ttymxc0,115200 root=/dev/mmcblk0p3
rootwait";
? ? ? ?};

@@ -47,29 +53,29 @@

? ? ? ? ? ? ? ? ? ? ? ?reg =<0x70000000 0x40000>;
? ? ? ? ? ? ? ? ? ? ? ?ranges;

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

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

- ? ? ? ? ? ? ? uart at 73fc0000 {
+ ? ? ? ? ? ? ? uart1: uart at 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++;
+ ? ? ? }

Rather than parsing the alias strings everytime, it would probably be
better to preprocess all the properties in the aliases node and create
a lookup table of alias->node references that can be walked quickly
and trivially.

Also, when obtaining an enumeration for a device, you'll need to be
careful about what number gets returned. ?If the node doesn't match a
given alias, but aliases do exist for other devices of like type, then
you need to be careful not to assign a number already assigned to
another device via an alias (this of course assumes the driver
supports dynamics enumeration, which many drivers will). ?It would be

\> ?+

quoted

+ ? ? ? 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;

Personally, it an alias isn't present, then I'd dynamically assign a port
id.

quoted

- ? ? ? 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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-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.