Commit 988437ae authored by Oleksij Rempel's avatar Oleksij Rempel Committed by Greg Kroah-Hartman
Browse files

nvmem: add snvs_lpgpr driver 



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: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent eeb8b493

drivers/nvmem/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -144,4 +144,14 @@ 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 SOC_IMX6 || COMPILE_TEST

	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

drivers/nvmem/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/nvmem/snvs_lpgpr.c

0 → 100644
+156 −0
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>

 * Copyright (c) 2017 Pengutronix, Oleksij Rempel <kernel@pengutronix.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/mfd/syscon.h>

#include <linux/module.h>

#include <linux/nvmem-provider.h>

#include <linux/of_device.h>

#include <linux/regmap.h>



#define IMX6Q_SNVS_HPLR		0x00

#define IMX6Q_GPR_SL		BIT(5)

#define IMX6Q_SNVS_LPLR		0x34

#define IMX6Q_GPR_HL		BIT(5)

#define IMX6Q_SNVS_LPGPR	0x68



struct snvs_lpgpr_cfg {

	int offset;

	int offset_hplr;

	int offset_lplr;

};



struct snvs_lpgpr_priv {

	struct device_d			*dev;

	struct regmap			*regmap;

	struct nvmem_config		cfg;

	const struct snvs_lpgpr_cfg	*dcfg;

};



static const struct snvs_lpgpr_cfg snvs_lpgpr_cfg_imx6q = {

	.offset		= IMX6Q_SNVS_LPGPR,

	.offset_hplr	= IMX6Q_SNVS_HPLR,

	.offset_lplr	= IMX6Q_SNVS_LPLR,

};



static int snvs_lpgpr_write(void *context, unsigned int offset, void *val,

			    size_t bytes)

{

	struct snvs_lpgpr_priv *priv = context;

	const struct snvs_lpgpr_cfg *dcfg = priv->dcfg;

	unsigned int lock_reg;

	int ret;



	ret = regmap_read(priv->regmap, dcfg->offset_hplr, &lock_reg);

	if (ret < 0)

		return ret;



	if (lock_reg & IMX6Q_GPR_SL)

		return -EPERM;



	ret = regmap_read(priv->regmap, dcfg->offset_lplr, &lock_reg);

	if (ret < 0)

		return ret;



	if (lock_reg & IMX6Q_GPR_HL)

		return -EPERM;



	return regmap_bulk_write(priv->regmap, dcfg->offset + offset, val,

				bytes / 4);

}



static int snvs_lpgpr_read(void *context, unsigned int offset, void *val,

			   size_t bytes)

{

	struct snvs_lpgpr_priv *priv = context;

	const struct snvs_lpgpr_cfg *dcfg = priv->dcfg;



	return regmap_bulk_read(priv->regmap, dcfg->offset + offset,

			       val, bytes / 4);

}



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;



	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->dcfg = dcfg;



	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 },

	{ .compatible = "fsl,imx6ul-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@pengutronix.de>");

MODULE_DESCRIPTION("Low Power General Purpose Register in i.MX6 Secure Non-Volatile Storage");

MODULE_LICENSE("GPL v2");

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