[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@pengutronix.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...

<--

+	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.

??

+#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 [off-list ref]");
+MODULE_DESCRIPTION("Low Power General Purpose Register in i.MX6 Secure Non-Volatile Storage");
+MODULE_LICENSE("GPL");

GPLv2??