Messages in this thread |  | | | From | Grant Likely <> | | Date | Tue, 21 Jun 2011 13:13:50 -0600 | | Subject | Re: [PATCH 1/3] serial/imx: add device tree support |
| |
On Tue, Jun 21, 2011 at 7:55 AM, Shawn Guo <shawn.guo@freescale.com> wrote: > 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...
> > 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; > + }; > +
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@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? > 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++; > + }
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
\> + > + 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.
> > - 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 > >
-- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |