linux-kernel - Re: [RFC PATCH v6 2/2] nvmem: Add Vybrid OCOTP and OCROM support

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Message-ID: <5589AD83.8050704@linaro.org>
Date:	Tue, 23 Jun 2015 20:03:31 +0100
From:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:	Sanchayan Maity <maitysanchayan@...il.com>,
	linux-arm-kernel@...ts.infradead.org,
	maxime.ripard@...e-electrons.com
CC:	shawn.guo@...aro.org, arnd@...db.de, kernel@...gutronix.de,
	stefan@...er.ch, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v6 2/2] nvmem: Add Vybrid OCOTP and OCROM support

Hi Sanchayan,


On 23/06/15 14:44, Sanchayan Maity wrote:
> The patch adds support for the On Chip One Time Programmable Peripheral
> (OCOTP) and On Chip ROM (OCROM) support.
>
> On Vybrid OCOTP contain data like SoC ID, MAC address and OCROM has the
> revision ID.
>
> Signed-off-by: Sanchayan Maity <maitysanchayan@...il.com>
> ---
>   drivers/nvmem/Kconfig       | 11 +++++++++
>   drivers/nvmem/Makefile      |  2 ++
>   drivers/nvmem/vf610-ocotp.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 73 insertions(+)
>   create mode 100644 drivers/nvmem/vf610-ocotp.c
>

Fantastic! diff is already looking good, when compared to v5 patches,
"drivers/soc/fsl/soc-vf610.c | 166 
+++++++++++++++++++++++++++++++++++++++++++"

I think, We could even do a better job by moving qfprom and this driver 
to a simple-mmio-nvmem provider, see below comments.

> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 17f1a57..557c1e0 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -33,4 +33,15 @@ config NVMEM_SUNXI_SID
>   	  This driver can also be built as a module. If so, the module
>   	  will be called eeprom-sunxi-sid.
>
> +config NVMEM_VF610_OCOTP
> +	tristate "VF610 SoCs OCOTP support"
> +	depends on SOC_VF610
> +	select REGMAP_MMIO
> +	help
> +	  This is a driver for the 'OCOTP' available on various Vybrid
> +	  devices.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called nvmem-vf610-ocotp.
> +
>   endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index cc46791..a9ed113 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -11,3 +11,5 @@ obj-$(CONFIG_QCOM_QFPROM)	+= nvmem_qfprom.o
>   nvmem_qfprom-y			:= qfprom.o
>   obj-$(CONFIG_NVMEM_SUNXI_SID)	+= nvmem-sunxi-sid.o
>   nvmem-sunxi-sid-y		:= sunxi-sid.o
> +obj-$(CONFIG_NVMEM_VF610_OCOTP)	+= nvmem-vf610-ocotp.o
> +nvmem-vf610-ocotp-y		:= vf610-ocotp.o
> diff --git a/drivers/nvmem/vf610-ocotp.c b/drivers/nvmem/vf610-ocotp.c
> new file mode 100644
> index 0000000..d98772d
> --- /dev/null
> +++ b/drivers/nvmem/vf610-ocotp.c
> @@ -0,0 +1,60 @@
> +/*
> + * Copyright (C) 2015 Sanchayan Maity <sanchayan.maity@...adex.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include "nvmem-mmio.h"
> +
> +static struct regmap_config regmap_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,

Any particular reason why it cant support byte reads?

This driver looks exactly same as qcom,qfprom driver, except the 
regmap_config.

> +};
> +
> +static struct nvmem_config ocotp_config = {
> +	.name = "soc_id",
> +};
> +
> +static struct nvmem_config rom_config = {
> +	.name = "rom_rev",
> +};
> +
> +static struct nvmem_mmio_data ocotp_data = {
> +	.nvmem_config = &ocotp_config,
> +	.regmap_config = &regmap_config,
> +};
> +
> +static struct nvmem_mmio_data rom_data = {
> +	.nvmem_config = &rom_config,
> +	.regmap_config = &regmap_config,
> +};
> +
> +static const struct of_device_id ocotp_of_match[] = {
> +	{ .compatible = "fsl,vf610-ocotp", .data = &ocotp_data},
> +	{ .compatible = "fsl,vf610-ocrom", .data = &rom_data},
> +	{/* sentinel */},
> +};
> +MODULE_DEVICE_TABLE(of, ocotp_of_match);
> +
> +static struct platform_driver vf610_ocotp_driver = {
> +	.probe = nvmem_mmio_probe,
> +	.remove = nvmem_mmio_remove,
> +	.driver = {
> +		.name = "vf610-nvmem",
> +		.of_match_table = ocotp_of_match,
> +	},
> +};
> +module_platform_driver(vf610_ocotp_driver);
> +MODULE_AUTHOR("Sanchayan Maity <sanchayan.maity@...adex.com>");
> +MODULE_DESCRIPTION("Vybrid NVMEM driver");
> +MODULE_LICENSE("GPL v2");
>


I moved the nvmem_mmio to qfprom as I did not any other user for that in 
v6 patches.

Now that Vybrid can be another user I should probably put it back, or 
may be I should create a simple-mmio-nvmem driver which both qcom,qfprom 
and Vybrid can use.

--srini
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