From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932359Ab1FVP2N (ORCPT ); Wed, 22 Jun 2011 11:28:13 -0400 Received: from va3ehsobe001.messaging.microsoft.com ([216.32.180.11]:56370 "EHLO VA3EHSOBE008.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932180Ab1FVP2L convert rfc822-to-8bit (ORCPT ); Wed, 22 Jun 2011 11:28:11 -0400 X-SpamScore: -20 X-BigFish: VS-20(zz9371M179dN1432N98dKzz1202hzz8275bhz2dh2a8h668h839h61h) X-Spam-TCS-SCL: 0:0 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPVD:NLI;H:mail.freescale.net;RD:none;EFVD:NLI Date: Wed, 22 Jun 2011 23:33:54 +0800 From: Shawn Guo To: Grant Likely CC: , , , Jason Liu , , Jeremy Kerr , Sascha Hauer , , David Gibson Subject: Re: [PATCH 1/3] serial/imx: add device tree support Message-ID: <20110622153353.GA25799@S2100-06.ap.freescale.net> References: <1308410354-21387-1-git-send-email-shawn.guo@linaro.org> <1308410354-21387-2-git-send-email-shawn.guo@linaro.org> <20110618161934.GH8195@ponder.secretlab.ca> <20110619073000.GA23171@S2100-06.ap.freescale.net> <20110621135558.GB9228@S2101-09.ap.freescale.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Content-Transfer-Encoding: 8BIT X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 21, 2011 at 01:13:50PM -0600, Grant Likely wrote: > On Tue, Jun 21, 2011 at 7:55 AM, Shawn Guo 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