From: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
To: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: U-Boot Mailing List
<u-boot-0aAXYlwwYIKGBzrmiIFOJg@public.gmane.org>,
Devicetree Discuss
<devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org>,
Tom Warren <TWarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
Albert ARIBAUD
<albert.u.boot-LhW3hqR2+23R7s880joybQ@public.gmane.org>
Subject: Re: [PATCH 02/14] fdt: Add functions to access phandles, arrays and bools
Date: Mon, 28 Nov 2011 11:41:32 -0700 [thread overview]
Message-ID: <4ED3D5DC.10502@nvidia.com> (raw)
In-Reply-To: <1322106896-23054-3-git-send-email-sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
On 11/23/2011 08:54 PM, Simon Glass wrote:
> Add a function to lookup a property which is a phandle in a node, and
> another to read a fixed-length integer array from an fdt property.
> Also add a function to read boolean properties.
>
> Signed-off-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Looking at the U-Boot custodians web page, you need to send the core DT
changes (well, probably anything DT related) to Jerry Van Baren.
> +/**
> + * Look up a property in a node and return its contents in an integer
> + * array of given length. The property must have at least enough data for
> + * the array (4*count bytes). It may have more, but this will be ignored.
> + *
> + * @param blob FDT blob
> + * @param node node to examine
> + * @param prop_name name of property to find
> + * @param array array to fill with data
> + * @param count number of array elements
> + * @return 0 if ok, or -FDT_ERR_NOTFOUND if the property is not found,
> + * or -FDT_ERR_BADLAYOUT if not enough data
> + */
> +int fdtdec_get_int_array(const void *blob, int node, const char *prop_name,
> + int *array, int count);
The kernel's equivalent of this function retrieves an array of U32s. Is
one version more correct than the other?
> +/**
> + * Look up a boolean property in a node and return it.
> + *
> + * A boolean properly is true if present in the device tree and false if not
> + * present, or present with a 0 value.
> + *
> + * @param blob FDT blob
> + * @param node node to examine
> + * @param prop_name name of property to find
> + * @return 1 if the properly is present; 0 if it isn't present or is 0
> + */
> +int fdtdec_get_bool(const void *blob, int node, const char *prop_name);
Does U-Boot allow use of the "bool" type here?
> +/**
> + * Look up a property in a node and check that it has a minimum length.
> + *
> + * @param blob FDT blob
> + * @param node node to examine
> + * @param prop_name name of property to find
> + * @param min_len minimum property length in bytes
> + * @param err 0 if ok, or -FDT_ERR_NOTFOUND if the property is not
> + found, or -FDT_ERR_BADLAYOUT if not enough data
> + * @return pointer to cell, which is only valid if err == 0
> + */
> +static const void *get_prop_len(const void *blob, int node,
> + const char *prop_name, int min_len, int *err)
Based on the function name, I'd expect it to return the length of the
property; perhaps get_prop_check_min_len?
> +/**
> + * Look up a boolean property in a node and return it.
> + *
> + * A boolean properly is true if present in the device tree and false if not
> + * present, or present with a 0 value.
> + *
> + * @param blob FDT blob
> + * @param node node to examine
> + * @param prop_name name of property to find
> + * @return 1 if the properly is present; 0 if it isn't present or is 0
> + */
> +int fdtdec_get_bool(const void *blob, int node, const char *prop_name)
> +{
> + const s32 *cell;
> + int len;
> +
> + debug("%s: %s\n", __func__, prop_name);
> + cell = fdt_getprop(blob, node, prop_name, &len);
> + if (!cell)
> + return 0;
> + if (len >= sizeof(u32) && *cell == 0)
> + return 0;
> +
> + return 1;
> +}
In the kernel, I believe that property existence is all that's usually
checked. Is that wrong? Did the definition of a boolean property's value
in the function description above come from the specification? If a
property had a length of 0/1/2/3 with a zero value, it seems very odd to
treat that as true.
--
nvpublic
next prev parent reply other threads:[~2011-11-28 18:41 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-24 3:54 [PATCH 01/14] fdt: Tidy up a few fdtdec problems Simon Glass
2011-11-24 3:54 ` [PATCH 03/14] arm: fdt: Ensure that an embedded fdt is word-aligned Simon Glass
2011-11-24 3:54 ` [PATCH 06/14] tegra: fdt: Add device tree file for Tegra2 Seaboard Simon Glass
[not found] ` <1322106896-23054-2-git-send-email-sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-11-24 3:54 ` [PATCH 02/14] fdt: Add functions to access phandles, arrays and bools Simon Glass
[not found] ` <1322106896-23054-3-git-send-email-sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-11-28 18:41 ` Stephen Warren [this message]
[not found] ` <4ED3D5DC.10502-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2011-11-29 5:12 ` David Gibson
2011-12-02 1:01 ` Simon Glass
[not found] ` <CAPnjgZ29tsNXd1+1eXdTHRjgh_MQJrXoc23_oqO9UPJ73mu7ZA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-02 15:55 ` Stephen Warren
2011-12-02 16:38 ` Simon Glass
2011-12-02 3:33 ` Jerry Van Baren
2011-12-02 4:58 ` Simon Glass
2011-12-02 17:22 ` Jerry Van Baren
2011-12-02 18:12 ` Simon Glass
2011-11-24 3:54 ` [PATCH 04/14] arm: fdt: Add skeleton device tree file Simon Glass
2011-11-24 3:54 ` [PATCH 05/14] tegra: fdt: Add Tegra2x " Simon Glass
[not found] ` <1322106896-23054-6-git-send-email-sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-11-28 18:56 ` Stephen Warren
2011-12-02 1:24 ` Simon Glass
[not found] ` <CAPnjgZ11cFm15E9MHXno_YGp0NxdOHhGBavYbQBP5Nu_TOtx7A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-02 15:58 ` Stephen Warren
2011-12-02 16:47 ` Simon Glass
2011-11-24 3:54 ` [PATCH 07/14] tegra: fdt: Add initial device tree definitions for USB ports Simon Glass
2011-11-24 3:54 ` [PATCH 14/14] tegra: fdt: Enable FDT support for Seaboard Simon Glass
2011-11-28 18:33 ` [PATCH 01/14] fdt: Tidy up a few fdtdec problems Stephen Warren
[not found] ` <4ED3D3F2.8070302-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2011-11-29 1:10 ` David Gibson
2011-12-01 20:59 ` Simon Glass
[not found] ` <1322106896-23054-11-git-send-email-sjg@chromium.org>
[not found] ` <4ED3DF1D.6080009@nvidia.com>
[not found] ` <CAPnjgZ1-yxq-O-vsy1gNJ8AOzh7Sz9j5PG9Tx1sKpnAxhApJAQ@mail.gmail.com>
[not found] ` <4EDD38AC.30908@nvidia.com>
[not found] ` <CAPnjgZ0MTaPa4pq1VXk_XbmuDyWTfy-H33W4deNVn2ALUrcW_A@mail.gmail.com>
[not found] ` <4EDD429E.8010507@nvidia.com>
[not found] ` <CAPnjgZ2G220G-i3PPtS4XJYY0ornWFOoK3=b93jG-6GE_g2O5w@mail.gmail.com>
[not found] ` <4EDD5F1B.5060205@nvidia.com>
[not found] ` <CAPnjgZ2h7F228q=pXuf7M9vTASurY3R5an_QV-mrETLf8nzA1A@mail.gmail.com>
[not found] ` <4EDE7E1C.2090203@nvidia.com>
[not found] ` <CAPnjgZ1G+mv6uv8SrdMm7DoqFjeeyVHYv6nbQxn9qixfbQMGvA@mail.gmail.com>
[not found] ` <CAPnjgZ1G+mv6uv8SrdMm7DoqFjeeyVHYv6nbQxn9qixfbQMGvA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-07 23:46 ` [PATCH 10/14] tegra: usb: Add support for USB peripheral Stephen Warren
2011-12-08 21:24 ` Simon Glass
[not found] ` <CAPnjgZ0AuBNkYKN0JHQyc7DdzwUSZivR+Dv2BkiFsKQBNMeP8A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-12 18:18 ` Stephen Warren
2011-12-12 18:42 ` Simon Glass
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