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Message-ID: <db48c285-996e-6e73-2bc9-4afd8941a937@linaro.org>
Date: Wed, 7 Jun 2017 17:44:37 +0100
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Oleksij Rempel <o.rempel@...gutronix.de>,
devicetree@...r.kernel.org, kernel@...gutronix.de,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Mark Rutland <mark.rutland@....com>,
Maxime Ripard <maxime.ripard@...e-electrons.com>,
Rob Herring <robh+dt@...nel.org>,
Shawn Guo <shawnguo@...nel.org>
Subject: Re: [PATCH v3 2/3] nvmem: add snvs_lpgpr driver
On 07/06/17 07:41, Oleksij Rempel wrote:
> This is a driver for Low Power General Purpose Register (LPGPR)
> available on i.MX6 SoCs in Secure Non-Volatile Storage (SNVS)
> of this chip.
>
> It is a 32-bit read/write register located in the low power domain.
> Since LPGPR is located in the battery-backed power domain, LPGPR can
> be used by any application for retaining data during an SoC power-down
> mode.
>
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
> drivers/nvmem/Kconfig | 13 +++++
> drivers/nvmem/Makefile | 2 +
> drivers/nvmem/snvs_lpgpr.c | 143 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 158 insertions(+)
> create mode 100644 drivers/nvmem/snvs_lpgpr.c
Minor comments...
>
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 101ced4c84be..00537b91cc22 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -144,4 +144,17 @@ config MESON_EFUSE
> This driver can also be built as a module. If so, the module
> will be called nvmem_meson_efuse.
>
> +config NVMEM_SNVS_LPGPR
> + tristate "Support for Low Power General Purpose Register"
<--
> + depends on HAS_IOMEM
> + depends on OF
> + select REGMAP_MMIO
-->
Not sure why we need this selects here, if you are accessing regmap via
syscon.
Consider adding COMPILE_TEST so that driver gets good test coverage.
> + select MFD_SYSCON
> + help
> + This is a driver for Low Power General Purpose Register (LPGPR) available on
> + i.MX6 SoCs in Secure Non-Volatile Storage (SNVS) of this chip.
> +
> + This driver can also be built as a module. If so, the module
> + will be called nvmem-snvs-lpgpr.
> +
> endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 173140658693..4c589184acee 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -30,3 +30,5 @@ obj-$(CONFIG_NVMEM_VF610_OCOTP) += nvmem-vf610-ocotp.o
> nvmem-vf610-ocotp-y := vf610-ocotp.o
> obj-$(CONFIG_MESON_EFUSE) += nvmem_meson_efuse.o
> nvmem_meson_efuse-y := meson-efuse.o
> +obj-$(CONFIG_NVMEM_SNVS_LPGPR) += nvmem_snvs_lpgpr.o
> +nvmem_snvs_lpgpr-y := snvs_lpgpr.o
> diff --git a/drivers/nvmem/snvs_lpgpr.c b/drivers/nvmem/snvs_lpgpr.c
> new file mode 100644
> index 000000000000..c90a8e8a161f
> --- /dev/null
> +++ b/drivers/nvmem/snvs_lpgpr.c
> @@ -0,0 +1,143 @@
> +/*
> + * Copyright (c) 2015 Pengutronix, Steffen Trumtrar <kernel@...gutronix.de>
> + * Copyright (c) 2017 Pengutronix, Oleksij Rempel <kernel@...gutronix.de>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation.
> + */
> +
> +#include <linux/clk.h>
??
> +#include <linux/device.h>
> +#include <linux/io.h>
??
> +#include <linux/module.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +
> +struct snvs_lpgpr_priv {
> + struct device_d *dev;
> + struct regmap *regmap;
> + int offset;
> + struct nvmem_config cfg;
> +};
> +
> +struct snvs_lpgpr_cfg {
> + int offset;
> +};
> +
> +static const struct snvs_lpgpr_cfg snvs_lpgpr_cfg_imx6q = {
> + .offset = 0x68,
> +};
> +
> +static int snvs_lpgpr_write(void *context, unsigned int offset, void *_val,
> + size_t bytes)
> +{
> + struct snvs_lpgpr_priv *priv = context;
> + const u32 *val = _val;
> + int i = 0, words = bytes / 4;
> +
> + while (words--)
> + regmap_write(priv->regmap, priv->offset + offset + (i++ * 4),
> + *val++);
> +
> + return 0;
> +}
> +
> +static int snvs_lpgpr_read(void *context, unsigned int offset, void *_val,
> + size_t bytes)
> +{
> + struct snvs_lpgpr_priv *priv = context;
> + u32 *val = _val;
> + int i = 0, words = bytes / 4;
> +
> + while (words--)
> + regmap_read(priv->regmap, priv->offset + offset + (i++ * 4),
> + val++);
> +
> + return 0;
> +}
> +
> +static int snvs_lpgpr_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *node = dev->of_node;
> + struct device_node *syscon_node;
> + struct snvs_lpgpr_priv *priv;
> + struct nvmem_config *cfg;
> + struct nvmem_device *nvmem;
> + const struct snvs_lpgpr_cfg *dcfg;
> + int err;
> +
> + if (!node)
> + return -ENOENT;
> +
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + dcfg = of_device_get_match_data(dev);
> + if (!dcfg)
> + return -EINVAL;
> +
> + syscon_node = of_get_parent(node);
> + if (!syscon_node)
> + return -ENODEV;
> +
> + priv->regmap = syscon_node_to_regmap(syscon_node);
> + of_node_put(syscon_node);
> + if (IS_ERR(priv->regmap))
> + return PTR_ERR(priv->regmap);
> +
> + priv->offset = dcfg->offset;
> +
> + cfg = &priv->cfg;
> + cfg->priv = priv;
> + cfg->name = dev_name(dev);
> + cfg->dev = dev;
> + cfg->stride = 4,
> + cfg->word_size = 4,
> + cfg->size = 4,
> + cfg->owner = THIS_MODULE,
> + cfg->reg_read = snvs_lpgpr_read,
> + cfg->reg_write = snvs_lpgpr_write,
> +
> + nvmem = nvmem_register(cfg);
> + if (IS_ERR(nvmem))
> + return PTR_ERR(nvmem);
> +
> + platform_set_drvdata(pdev, nvmem);
> +
> + return 0;
> +}
> +
> +static int snvs_lpgpr_remove(struct platform_device *pdev)
> +{
> + struct nvmem_device *nvmem = platform_get_drvdata(pdev);
> +
> + return nvmem_unregister(nvmem);
> +}
> +
> +static const struct of_device_id snvs_lpgpr_dt_ids[] = {
> + { .compatible = "fsl,imx6q-snvs-lpgpr", .data = &snvs_lpgpr_cfg_imx6q },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, snvs_lpgpr_dt_ids);
> +
> +static struct platform_driver snvs_lpgpr_driver = {
> + .probe = snvs_lpgpr_probe,
> + .remove = snvs_lpgpr_remove,
> + .driver = {
> + .name = "snvs_lpgpr",
> + .of_match_table = snvs_lpgpr_dt_ids,
> + },
> +};
> +module_platform_driver(snvs_lpgpr_driver);
> +
> +MODULE_AUTHOR("Oleksij Rempel <o.rempel@...gutronix.de>");
> +MODULE_DESCRIPTION("Low Power General Purpose Register in i.MX6 Secure Non-Volatile Storage");
> +MODULE_LICENSE("GPL");
GPLv2??
>
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