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[92.233.226.227]) by smtp.googlemail.com with ESMTPSA id r2sm3572882wrt.8.2021.03.05.02.02.26 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 05 Mar 2021 02:02:26 -0800 (PST) Subject: Re: [PATCH 2/2] nvmem: iomap: new driver exposing NVMEM accessible using I/O mapping To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , Rob Herring Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, Florian Fainelli , Vivek Unune , bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org, =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= References: <20210304144132.24098-1-zajec5@gmail.com> <20210304144132.24098-2-zajec5@gmail.com> From: Srinivas Kandagatla Message-ID: <047bced8-6c20-4a0a-c7ea-e0ad83318461@linaro.org> Date: Fri, 5 Mar 2021 10:02:25 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20210304144132.24098-2-zajec5@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 04/03/2021 14:41, Rafał Miłecki wrote: > From: Rafał Miłecki > > This is a generic NVMEM access method used e.g. by Broadcom for their > NVRAM on MIPS and Northstar devices. > > Signed-off-by: Rafał Miłecki > --- > drivers/nvmem/Kconfig | 7 +++ > drivers/nvmem/Makefile | 2 + > drivers/nvmem/iomap.c | 99 ++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 108 insertions(+) > create mode 100644 drivers/nvmem/iomap.c > > diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig > index 75d2594c16e1..3d5c5684685d 100644 > --- a/drivers/nvmem/Kconfig > +++ b/drivers/nvmem/Kconfig > @@ -278,4 +278,11 @@ config NVMEM_RMEM > > This driver can also be built as a module. If so, the module > will be called nvmem-rmem. > + > +config NVMEM_IOMAP > + tristate "I/O mapped NVMEM support" > + depends on HAS_IOMEM > + help > + This driver supports NVMEM that can be accessed using I/O mapping. > + > endif > diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile > index 5376b8e0dae5..88a3b6979c53 100644 > --- a/drivers/nvmem/Makefile > +++ b/drivers/nvmem/Makefile > @@ -57,3 +57,5 @@ obj-$(CONFIG_SPRD_EFUSE) += nvmem_sprd_efuse.o > nvmem_sprd_efuse-y := sprd-efuse.o > obj-$(CONFIG_NVMEM_RMEM) += nvmem-rmem.o > nvmem-rmem-y := rmem.o > +obj-$(CONFIG_NVMEM_IOMAP) += nvmem_iomap.o > +nvmem_iomap-y := iomap.o > diff --git a/drivers/nvmem/iomap.c b/drivers/nvmem/iomap.c > new file mode 100644 > index 000000000000..ab6b40858a64 > --- /dev/null > +++ b/drivers/nvmem/iomap.c > @@ -0,0 +1,99 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2021 Rafał Miłecki > + */ > + > +#include > +#include > +#include > +#include > +#include > + > +struct iomap { > + struct device *dev; > + void __iomem *base; > +}; > + > +static int iomap_read(void *context, unsigned int offset, void *val, > + size_t bytes) > +{ > + struct iomap *priv = context; > + u8 *src = priv->base + offset; > + u8 *dst = val; > + size_t tmp; > + > + tmp = offset % 4; > + memcpy_fromio(dst, src, tmp); > + dst += tmp; > + src += tmp; > + bytes -= tmp; > + > + tmp = rounddown(bytes, 4); > + __ioread32_copy(dst, src, tmp / 4); > + dst += tmp; > + src += tmp; > + bytes -= tmp; > + > + memcpy_fromio(dst, src, bytes); > + You could just do this! while (bytes--) *val++ = readb(priv->base + offset + i++); > + return 0; > +} > + > +static int iomap_probe(struct platform_device *pdev) > +{ > + struct nvmem_config config = { > + .name = "iomap", > + .reg_read = iomap_read, > + }; > + struct device *dev = &pdev->dev; > + struct resource *res; > + struct iomap *priv; > + > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); > + if (!priv) > + return -ENOMEM; > + priv->dev = dev; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + if (!res) { > + dev_err(dev, "Failed to get resource\n"); > + return -ENODEV; > + } This is redundant check and error message! You can just do : res = platform_get_resource(pdev, IORESOURCE_MEM, 0); priv->base = devm_ioremap_resource(dev, res); > + > + priv->base = devm_ioremap_resource(dev, res); > + if (IS_ERR(priv->base)) { > + dev_err(dev, "Failed to map resource: %ld\n", PTR_ERR(priv->base)); This message is redundant! > + return PTR_ERR(priv->base); > + } > + > + config.dev = dev; > + config.priv = priv; > + config.size = resource_size(res); > + > + return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config)); > +} > + > +static const struct of_device_id iomap_of_match_table[] = { > + { .compatible = "brcm,nvram", }, > + { .compatible = "nvmem-iomap", }, Generic compatible does not really makes sense at all, you can probably consider adding some generic functions rather than having a compatible, in case you want to reduce code duplication! > + {}, > +}; > + > +static struct platform_driver iomap_driver = { > + .probe = iomap_probe, > + .driver = { > + .name = "nvmem_iomap", > + .of_match_table = iomap_of_match_table, > + }, > +}; > + > +static int __init iomap_init(void) > +{ > + return platform_driver_register(&iomap_driver); > +} > + > +subsys_initcall_sync(iomap_init); > + > +MODULE_AUTHOR("Rafał Miłecki"); > +MODULE_LICENSE("GPL v2"); it should be MODULE_LICENSE("GPL"); > +MODULE_DEVICE_TABLE(of, iomap_of_match_table); >