From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757491Ab1FUTi1 (ORCPT ); Tue, 21 Jun 2011 15:38:27 -0400 Received: from mail-gx0-f174.google.com ([209.85.161.174]:52885 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757441Ab1FUTiY convert rfc822-to-8bit (ORCPT ); Tue, 21 Jun 2011 15:38:24 -0400 MIME-Version: 1.0 In-Reply-To: <4E00F290.2010303@firmworks.com> 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> <4E00F290.2010303@firmworks.com> From: Grant Likely Date: Tue, 21 Jun 2011 13:38:03 -0600 X-Google-Sender-Auth: 768Ztvm6ydCGE5_7VT-RKh15hh0 Message-ID: Subject: Re: [PATCH 1/3] serial/imx: add device tree support To: Mitch Bradley Cc: patches@linaro.org, netdev@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, Jason Liu , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jeremy Kerr , Sascha Hauer , Shawn Guo Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 21, 2011 at 1:35 PM, Mitch Bradley wrote: > What is the problem with > > aliases{ >   serial0 = "/uart@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: >> >> 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? >> >>>        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 >>> >>> >> >> >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- Grant Likely, B.Sc., P.Eng. 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