From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD818C2B9F8 for ; Tue, 25 May 2021 19:33:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B121D61413 for ; Tue, 25 May 2021 19:33:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230188AbhEYTfJ (ORCPT ); Tue, 25 May 2021 15:35:09 -0400 Received: from fllv0016.ext.ti.com ([198.47.19.142]:44822 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229750AbhEYTfI (ORCPT ); Tue, 25 May 2021 15:35:08 -0400 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id 14PJXRHf044419; Tue, 25 May 2021 14:33:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1621971207; bh=EihITSZ+agD5NRPVu+oqyk24Asa0tc2ILpQ40bXNrcA=; h=Date:From:To:CC:Subject:References:In-Reply-To; b=kPxYpFZDUB8EPq/lPR3srxivyHfOM89VrLNj/S16j70XPmtRp56HlmI+12Q/TxME9 +t2RuOY2of1TIbjvR0DQ04abHj7AcBfm4VBEh5o8MbdRJtpgF9PXLhUKqdljJIqqAO QiqA8YikYp/sKpO7IhyOH64mZNiF2WoJ0QFJ+CYI= Received: from DFLE114.ent.ti.com (dfle114.ent.ti.com [10.64.6.35]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 14PJXRPK059214 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 25 May 2021 14:33:27 -0500 Received: from DFLE105.ent.ti.com (10.64.6.26) by DFLE114.ent.ti.com (10.64.6.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Tue, 25 May 2021 14:33:27 -0500 Received: from fllv0040.itg.ti.com (10.64.41.20) by DFLE105.ent.ti.com (10.64.6.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2 via Frontend Transport; Tue, 25 May 2021 14:33:27 -0500 Received: from localhost (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id 14PJXQ7a023176; Tue, 25 May 2021 14:33:27 -0500 Date: Wed, 26 May 2021 01:03:26 +0530 From: Pratyush Yadav To: Michael Walle CC: , , Tudor Ambarus , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra Subject: Re: [PATCH v4 3/4] mtd: spi-nor: otp: return -EROFS if region is read-only Message-ID: <20210525193323.xdvbq3tab6oxk6yh@ti.com> References: <20210521194034.15249-1-michael@walle.cc> <20210521194034.15249-4-michael@walle.cc> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20210521194034.15249-4-michael@walle.cc> User-Agent: NeoMutt/20171215 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/05/21 09:40PM, Michael Walle wrote: > SPI NOR flashes will just ignore program commands if the OTP region is > locked. Thus, a user might not notice that the intended write didn't end > up in the flash. Return -EROFS to the user in this case. From what I can > tell, chips/cfi_cmdset_0001.c also return this error code. > > One could optimize spi_nor_mtd_otp_range_is_locked() to read the status > register only once and not for every OTP region, but for that we would > need some more invasive changes. Given that this is > one-time-programmable memory and the normal access mode is reading, we > just live with the small overhead. Ok. > > Fixes: 069089acf88b ("mtd: spi-nor: add OTP support") > Signed-off-by: Michael Walle > --- > drivers/mtd/spi-nor/otp.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c > index 3898ed67ba1c..b87f96593c13 100644 > --- a/drivers/mtd/spi-nor/otp.c > +++ b/drivers/mtd/spi-nor/otp.c > @@ -249,6 +249,31 @@ static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len, > return ret; > } > > +static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs, > + size_t len) > +{ > + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; > + unsigned int region; > + int locked; > + > + if (!len) > + return 0; I was inclined to say that the loop conditional below would take care of this but it can cause an underflow when ofs and len are both 0. > + > + /* > + * If any of the affected OTP regions are locked the entire range is > + * considered locked. > + */ > + for (region = spi_nor_otp_offset_to_region(nor, ofs); > + region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1); > + region++) { > + locked = ops->is_locked(nor, region); > + if (locked) > + return locked; > + } Ok. > + > + return 0; > +} > + > static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, > size_t total_len, size_t *retlen, > const u8 *buf, bool is_write) > @@ -271,6 +296,16 @@ static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, > /* don't access beyond the end */ > total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); > > + if (is_write) { > + ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len); > + if (ret < 0) { > + goto out; > + } else if (ret) { > + ret = -EROFS; I wonder if we should have a dev_info() or dev_err() here. I think this warrants a dev_dbg() at least. > + goto out; > + } So it returns -errno when the check for is_locked() fails and 1 or 0 when it is locked or not. Ok. It would be nice if you add a dev_dbg or dev_err() or dev_info() above. Nonetheless, Reviewed-by: Pratyush Yadav > + } > + > *retlen = 0; > while (total_len) { > /* -- Regards, Pratyush Yadav Texas Instruments Inc.