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[68.101.123.102]) by smtp.googlemail.com with ESMTPSA id w141sm21767677oie.1.2019.04.16.17.29.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Apr 2019 17:29:18 -0700 (PDT) Subject: Re: [PATCH] of_net: add mtd-mac-address support to of_get_mac_address() To: =?UTF-8?Q?Petr_=c5=a0tetiar?= , netdev@vger.kernel.org, devicetree@vger.kernel.org Cc: "David S. Miller" , Rob Herring , Mark Rutland , Andrew Lunn , Heiner Kallweit , Frank Rowand , John Crispin , Felix Fietkau References: <1555445100-30936-1-git-send-email-ynezz@true.cz> From: Florian Fainelli Message-ID: Date: Tue, 16 Apr 2019 17:29:16 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <1555445100-30936-1-git-send-email-ynezz@true.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 16/04/2019 13:05, Petr Štetiar wrote: > From: John Crispin > > Many embedded devices have information such as MAC addresses stored > inside MTD devices. This patch allows us to add a property inside a node > describing a network interface. The new property points at a MTD > partition with an offset where the MAC address can be found. > > This patch has originated in OpenWrt some time ago, so in order to > consider usefulness of this patch, here are some real-world numbers > which hopefully speak for themselves: > > * mtd-mac-address used 497 times in 357 device tree files > * mtd-mac-address-increment used 74 times in 58 device tree files > * mtd-mac-address-increment-byte used 1 time in 1 device tree file > > Signed-off-by: John Crispin > Signed-off-by: Felix Fietkau > [cleanup of the patch for upstream submission] > Signed-off-by: Petr Štetiar > --- [snip] > +static const void *of_get_mac_address_mtd(struct device_node *np) > +{ > +#ifdef CONFIG_MTD > + void *addr; > + size_t retlen; > + int size, ret; > + u8 mac[ETH_ALEN]; > + phandle phandle; > + const char *part; > + const __be32 *list; > + struct mtd_info *mtd; > + struct property *prop; > + u32 mac_inc = 0; > + u32 inc_idx = ETH_ALEN-1; > + struct device_node *mtd_np = NULL; Reverse christmas tree would look a bit nicer here. > + > + list = of_get_property(np, "mtd-mac-address", &size); > + if (!list || (size != (2 * sizeof(*list)))) > + return NULL; > + > + phandle = be32_to_cpup(list++); > + if (phandle) > + mtd_np = of_find_node_by_phandle(phandle); > + > + if (!mtd_np) > + return NULL; > + > + part = of_get_property(mtd_np, "label", NULL); > + if (!part) > + part = mtd_np->name; > + > + mtd = get_mtd_device_nm(part); > + if (IS_ERR(mtd)) > + return NULL; > + > + ret = mtd_read(mtd, be32_to_cpup(list), ETH_ALEN, &retlen, mac); > + put_mtd_device(mtd); > + > + of_property_read_u32(np, "mtd-mac-address-increment-byte", &inc_idx); of_property_read_u8() would probably be good here since this can't be bigger than 5 anyway. > + if (inc_idx > ETH_ALEN-1) > + return NULL; > > + if (!of_property_read_u32(np, "mtd-mac-address-increment", &mac_inc)) > + mac[inc_idx] += mac_inc; If I use a number greater than and included 128; this will cause a roll over, should this be range checked? Similarly, using of_property_read_u8() might be a better fit? Other than those, LGTM -- Florian