Messages in this thread | | | Date | Wed, 22 Jun 2011 23:33:54 +0800 | From | Shawn Guo <> | Subject | Re: [PATCH 1/3] serial/imx: add device tree support |
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On Tue, Jun 21, 2011 at 01:13:50PM -0600, Grant Likely wrote: > 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? > Another dependency the patch has to wait for? Or we can go ahead and utilize the facility later when it gets ready?
> > 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. > Ok, I'm thinking about it. Will probably ask something on details later.
> 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 > Some words not finished?
> \> + > > + 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. > We probably can not. The driver works with being told the correct port id which is defined by soc. Instead of dynamically assigning a port id, we have to tell the driver the exact hardware port id of the device that is being probed.
-- Regards, Shawn
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