Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755947AbdCGSxT (ORCPT ); Tue, 7 Mar 2017 13:53:19 -0500 Received: from mail.free-electrons.com ([62.4.15.54]:38070 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754333AbdCGSxQ (ORCPT ); Tue, 7 Mar 2017 13:53:16 -0500 Date: Tue, 7 Mar 2017 19:52:57 +0100 From: Boris Brezillon To: Alban Cc: linux-kernel@vger.kernel.org, Srinivas Kandagatla , Maxime Ripard , Rob Herring , Mark Rutland , David Woodhouse , Brian Norris , Marek Vasut , Richard Weinberger , Cyrille Pitchen , devicetree@vger.kernel.org, linux-mtd@lists.infradead.org, Moritz Fischer Subject: Re: [PATCH v2 2/2] mtd: Add support for reading MTD devices via the nvmem API Message-ID: <20170307195257.10d1fd06@bbrezillon> In-Reply-To: <1488875164-30440-3-git-send-email-albeu@free.fr> References: <1488875164-30440-1-git-send-email-albeu@free.fr> <1488875164-30440-3-git-send-email-albeu@free.fr> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7222 Lines: 245 On Tue, 7 Mar 2017 09:26:04 +0100 Alban wrote: > Allow drivers that use the nvmem API to read data stored on MTD devices. > Add an option to the MTD core that allow registering the MTD as > read-only NVMEM providers. > > Signed-off-by: Alban > --- > Changelog: > v2: * Moved to the MTD core instead of using notifiers > * Fixed the Kconfig description > --- > drivers/mtd/Kconfig | 9 +++++++ > drivers/mtd/Makefile | 1 + > drivers/mtd/mtdcore.c | 13 +++++++++ > drivers/mtd/mtdnvmem.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++ > drivers/mtd/mtdnvmem.h | 25 +++++++++++++++++ > include/linux/mtd/mtd.h | 4 +++ > 6 files changed, 124 insertions(+) > create mode 100644 drivers/mtd/mtdnvmem.c > create mode 100644 drivers/mtd/mtdnvmem.h > > diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig > index e83a279..5a34c6a 100644 > --- a/drivers/mtd/Kconfig > +++ b/drivers/mtd/Kconfig > @@ -322,6 +322,15 @@ config MTD_PARTITIONED_MASTER > the parent of the partition device be the master device, rather than > what lies behind the master. > > +config MTD_NVMEM > + bool "Register MTD devices as NVMEM providers" > + default y > + depends on NVMEM || COMPILE_TEST > + help > + Provides support for reading config data from MTD devices. This can > + be used by drivers to read device specific data such as MAC addresses > + or calibration results. > + > source "drivers/mtd/chips/Kconfig" > > source "drivers/mtd/maps/Kconfig" > diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile > index 99bb9a1..879a542 100644 > --- a/drivers/mtd/Makefile > +++ b/drivers/mtd/Makefile > @@ -5,6 +5,7 @@ > # Core functionality. > obj-$(CONFIG_MTD) += mtd.o > mtd-y := mtdcore.o mtdsuper.o mtdconcat.o mtdpart.o mtdchar.o > +mtd-$(CONFIG_MTD_NVMEM) += mtdnvmem.o > > obj-$(CONFIG_MTD_OF_PARTS) += ofpart.o > obj-$(CONFIG_MTD_REDBOOT_PARTS) += redboot.o > diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c > index 66a9ded..bb88997 100644 > --- a/drivers/mtd/mtdcore.c > +++ b/drivers/mtd/mtdcore.c > @@ -45,6 +45,7 @@ > #include > > #include "mtdcore.h" > +#include "mtdnvmem.h" > > static struct backing_dev_info *mtd_bdi; > > @@ -554,6 +555,11 @@ int add_mtd_device(struct mtd_info *mtd) > if (error) > goto fail_added; > > + /* Add the nvmem provider */ > + error = mtd_nvmem_add(mtd); > + if (error) > + goto fail_nvmem_add; > + > device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL, > "mtd%dro", i); > > @@ -571,6 +577,8 @@ int add_mtd_device(struct mtd_info *mtd) > __module_get(THIS_MODULE); > return 0; > > +fail_nvmem_add: > + device_unregister(&mtd->dev); > fail_added: > of_node_put(mtd_get_of_node(mtd)); > idr_remove(&mtd_idr, i); > @@ -611,6 +619,11 @@ int del_mtd_device(struct mtd_info *mtd) > mtd->index, mtd->name, mtd->usecount); > ret = -EBUSY; > } else { > + /* Try to remove the NVMEM provider */ > + ret = mtd_nvmem_remove(mtd); > + if (ret) > + goto out_error; > + > device_unregister(&mtd->dev); > > idr_remove(&mtd_idr, mtd->index); > diff --git a/drivers/mtd/mtdnvmem.c b/drivers/mtd/mtdnvmem.c > new file mode 100644 > index 0000000..d6bc402 > --- /dev/null > +++ b/drivers/mtd/mtdnvmem.c > @@ -0,0 +1,72 @@ > +/* > + * Copyright (C) 2017 Alban Bedel > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + */ > + > +#include > +#include > +#include > +#include > + > +static int mtd_nvmem_reg_read(void *priv, unsigned int offset, > + void *val, size_t bytes) > +{ > + struct mtd_info *mtd = priv; > + size_t retlen; > + int err; > + > + err = mtd_read(mtd, offset, bytes, &retlen, val); > + if (err && err != -EUCLEAN) > + return err; > + > + return retlen == bytes ? 0 : -EIO; > +} > + > +int mtd_nvmem_add(struct mtd_info *mtd) > +{ > + struct device_node *np = dev_of_node(&mtd->dev); > + struct nvmem_config config = {}; > + > + /* OF devices must have the nvmem-provider property */ > + if (np && !of_property_read_bool(np, "nvmem-provider")) > + return 0; > + > + config.dev = &mtd->dev; > + config.owner = THIS_MODULE; > + config.reg_read = mtd_nvmem_reg_read; > + config.size = mtd->size; > + config.word_size = 1; > + config.stride = 1; > + config.read_only = true; > + config.priv = mtd; > + > + mtd->nvmem = nvmem_register(&config); > + if (IS_ERR(mtd->nvmem)) { > + dev_err(&mtd->dev, "Failed to register NVMEM device\n"); > + return PTR_ERR(mtd->nvmem); > + } > + > + return 0; > +} > + > +int mtd_nvmem_remove(struct mtd_info *mtd) > +{ > + int ret; > + > + if (!mtd->nvmem) > + return 0; > + > + ret = nvmem_unregister(mtd->nvmem); > + if (ret) > + dev_err(&mtd->dev, "Failed to unregister NVMEM device\n"); > + > + return ret; > +} Given the amount of code I wonder if this shouldn't be integrated in mtdcore.c and unconditionally compiled in. > + > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Alban Bedel "); > +MODULE_DESCRIPTION("Driver to read config data from MTD devices"); > diff --git a/drivers/mtd/mtdnvmem.h b/drivers/mtd/mtdnvmem.h > new file mode 100644 > index 0000000..a49d8bd > --- /dev/null > +++ b/drivers/mtd/mtdnvmem.h > @@ -0,0 +1,25 @@ > +/* > + * Copyright (C) 2017 Alban Bedel > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + */ > +#ifndef MTD_NVMEM_H > +#define MTD_NVMEM_H 1 > + > +struct mtd_info; > + > +#ifdef CONFIG_MTD_NVMEM > +int mtd_nvmem_add(struct mtd_info *mtd); > +int mtd_nvmem_remove(struct mtd_info *mtd); > +#else > +static inline int mtd_nvmem_add(struct mtd_info *mtd) > +{ return 0; } > + > +static inline int mtd_nvmem_remove(struct mtd_info *mtd) > +{ return 0; } > +#endif > + > +#endif /* MTD_NVMEM_H */ > diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h > index eebdc63..e06c6e6 100644 > --- a/include/linux/mtd/mtd.h > +++ b/include/linux/mtd/mtd.h > @@ -205,6 +205,7 @@ struct mtd_pairing_scheme { > }; > > struct module; /* only needed for owner field in mtd_info */ > +struct nvmem_device; Include nvmem-provider.h instead of re-defining struct nvmem_device here. > > struct mtd_info { > u_char type; > @@ -351,6 +352,9 @@ struct mtd_info { > struct module *owner; > struct device dev; > int usecount; > +#if IS_ENABLED(CONFIG_MTD_NVMEM) > + struct nvmem_device *nvmem; > +#endif Hm, I don't see any #if IS_ENABLED() or #ifdef CONFIG_ statements in this file. I know it adds an extra 32/64 bits field for nothing if the feature is disabled, but how about keeping the struct definition simple by unconditionally adding the nvmem field. > }; > > int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,