Messages in this thread | | | Date | Wed, 1 Feb 2023 18:41:42 +0900 | Subject | Re: [PATCH 2/4] nvmem: add generic driver for devices with MMIO access | From | Kunihiko Hayashi <> |
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Hi,
On 2023/02/01 15:47, Rafał Miłecki wrote: > From: Rafał Miłecki <rafal@milecki.pl> > > With nvmem layouts in place we should now work on plain content access > NVMEM drivers (e.g. MMIO one). Actual NVMEM content handling should go > to layout drivers. > > Signed-off-by: Rafał Miłecki <rafal@milecki.pl> > --- > drivers/nvmem/Kconfig | 10 ++++++ > drivers/nvmem/Makefile | 2 ++ > drivers/nvmem/mmio.c | 80 ++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 92 insertions(+) > create mode 100644 drivers/nvmem/mmio.c > > diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig > index 789729ff7e50..9eb5e93f0455 100644 > --- a/drivers/nvmem/Kconfig > +++ b/drivers/nvmem/Kconfig > @@ -170,6 +170,16 @@ config NVMEM_MICROCHIP_OTPC > This driver enable the OTP controller available on Microchip SAMA7G5 > SoCs. It controls the access to the OTP memory connected to it. > > +config NVMEM_MMIO > + tristate "MMIO access based NVMEM support" > + depends on HAS_IOMEM > + help > + This driver provides support for NVMEM devices that can be accessed > + using MMIO. > + > + This driver can also be built as a module. If so, the module > + will be called nvmem-mmio. > + > config NVMEM_MTK_EFUSE > tristate "Mediatek SoCs EFUSE support" > depends on ARCH_MEDIATEK || COMPILE_TEST > diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile > index 442f9a4876a5..2f2bed7cdf24 100644 > --- a/drivers/nvmem/Makefile > +++ b/drivers/nvmem/Makefile > @@ -36,6 +36,8 @@ obj-$(CONFIG_NVMEM_MESON_MX_EFUSE) += > nvmem_meson_mx_efuse.o > nvmem_meson_mx_efuse-y := meson-mx-efuse.o > obj-$(CONFIG_NVMEM_MICROCHIP_OTPC) += nvmem-microchip-otpc.o > nvmem-microchip-otpc-y := microchip-otpc.o > +obj-$(CONFIG_NVMEM_MMIO) += nvmem-mmio.o > +nvmem-mmio-y := mmio.o > obj-$(CONFIG_NVMEM_MTK_EFUSE) += nvmem_mtk-efuse.o > nvmem_mtk-efuse-y := mtk-efuse.o > obj-$(CONFIG_NVMEM_MXS_OCOTP) += nvmem-mxs-ocotp.o > diff --git a/drivers/nvmem/mmio.c b/drivers/nvmem/mmio.c > new file mode 100644 > index 000000000000..19c8880dc675 > --- /dev/null > +++ b/drivers/nvmem/mmio.c > @@ -0,0 +1,80 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2023 Rafał Miłecki <rafal@milecki.pl> > + */ > + > +#include <linux/io.h> > +#include <linux/mod_devicetable.h> > +#include <linux/module.h> > +#include <linux/nvmem-provider.h> > +#include <linux/platform_device.h> > +#include <linux/property.h> > +#include <linux/slab.h> > + > +struct mmio_nvmem { > + void __iomem *base; > +}; > + > +static int mmio_nvmem_read(void *context, unsigned int offset, void *val, > size_t bytes) > +{ > + struct mmio_nvmem *priv = context; > + > + memcpy_fromio(val, priv->base, bytes); > + > + return 0; > +} > + > +static int mmio_nvmem_probe(struct platform_device *pdev) > +{ > + struct nvmem_config config = { > + .name = "mmio-nvmem",
The fixed name breaks sysfs for multiple nvmem instances.
sysfs: cannot create duplicate filename '/bus/nvmem/devices/mmio-nvmem0'
> + .read_only = true,
As Michael said in the mediatek patch, I also think it's hard to make read-only fixed in the generic driver.
> + .reg_read = mmio_nvmem_read, > + }; > + struct device *dev = &pdev->dev; > + struct mmio_nvmem *priv; > + struct resource *res; > + > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); > + if (!priv) > + return -ENOMEM; > + > + priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res); > + if (IS_ERR(priv->base)) > + return PTR_ERR(priv->base); > + > + config.dev = dev; > + config.size = resource_size(res); > + config.word_size = sizeof(u8); > + config.stride = sizeof(u8); > + config.priv = priv; > + > + if (!device_property_present(dev, "read-only")) > + dev_warn(dev, "Writing is not supported yet");
Isn't the logic opposite? Anyway, the driver doesn't use "read-only" properties for selection.
> + > + return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config)); > +} > + > +static const struct of_device_id mmio_nvmem_of_match_table[] = { > + { .compatible = "mmio-nvmem", }, > + {}, > +}; > + > +static struct platform_driver mmio_nvmem_driver = { > + .probe = mmio_nvmem_probe, > + .driver = { > + .name = "mmio_nvmem", > + .of_match_table = mmio_nvmem_of_match_table, > + }, > +}; > + > +static int __init mmio_nvmem_init(void) > +{ > + return platform_driver_register(&mmio_nvmem_driver); > +} > + > +subsys_initcall_sync(mmio_nvmem_init); > + > +MODULE_AUTHOR("Rafał Miłecki"); > +MODULE_LICENSE("GPL"); > +MODULE_DEVICE_TABLE(of, mmio_nvmem_of_match_table);
Thank you,
--- Best Regards Kunihiko Hayashi
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