[PATCH V5 0/3] nvmem: add ocotp support for i.MX23 and i.MX28

[PATCH V5 0/3] nvmem: add ocotp support for i.MX23 and i.MX28

[Stefan Wahren]

This patch series brings read-only support for the On-Chip OTP cells
in the i.MX23 and i.MX28 processor.

changes in V5:
- rebase to char-misc-next
- add nvmem prefix to module name
- set status in dtsi files

changes in V4:
- rename fsl_ocotp.c to mxs-ocotp.c
- adapt driver to use NVMEM framework V7
- take care of hbus clock
- increase too small timeout
- implement a wait function
- use defines from stmp_device.h
- remove owner init
- more code cleanup

changes in V3:
- drop write support
- take care of i.MX23 which has less registers
- drop unnecessary header file
- move static variables into driver data
- add devicetree probing
- fix missing bank closing in error case
- use kobj from platform device for sysfs
- add SYSFS to Kconfig
- add binding file
- code cleanup

Stefan Wahren (3):
  DT: nvmem: add binding for mxs-ocotp
  nvmem: add driver for ocotp in i.MX23 and i.MX28
  ARM: mxs: enable ocotp for i.MX23 and i.MX28

 .../devicetree/bindings/nvmem/mxs-ocotp.txt        |   24 ++
 arch/arm/boot/dts/imx23.dtsi                       |    7 +-
 arch/arm/boot/dts/imx28.dtsi                       |    7 +-
 drivers/nvmem/Kconfig                              |   11 +
 drivers/nvmem/Makefile                             |    2 +
 drivers/nvmem/mxs-ocotp.c                          |  252 ++++++++++++++++++++
 6 files changed, 299 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/nvmem/mxs-ocotp.txt
 create mode 100644 drivers/nvmem/mxs-ocotp.c

-- 
1.7.9.5

[PATCH V5 1/3] DT: nvmem: add binding for mxs-ocotp

[Stefan Wahren]

This patch adds the devicetree bindings for the Freescale MXS On Chip
OTP driver.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 .../devicetree/bindings/nvmem/mxs-ocotp.txt        |   24 ++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/mxs-ocotp.txt

diff --git a/Documentation/devicetree/bindings/nvmem/mxs-ocotp.txt b/Documentation/devicetree/bindings/nvmem/mxs-ocotp.txt
new file mode 100644
index 0000000..cd2a8cd
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/mxs-ocotp.txt
@@ -0,0 +1,24 @@
+On-Chip OTP Memory for Freescale i.MX23/i.MX28
+
+Required properties:
+- compatible:
+  - "fsl,imx23-ocotp" for i.MX23
+  - "fsl,imx28-ocotp" for i.MX28
+- #address-cells : Should be 1
+- #size-cells : Should be 1
+- reg : Address and length of OTP controller registers
+- clocks : Should contain a reference to the HBus clock
+
+= Data cells =
+Are child nodes of mxs-ocotp, bindings of which as described in
+bindings/nvmem/nvmem.txt
+
+Example for i.MX28:
+
+	ocotp: ocotp at 8002c000 {
+		compatible = "fsl,imx28-ocotp", "fsl,ocotp";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		reg = <0x8002c000 0x2000>;
+		clocks = <&clks 25>;
+	};
-- 
1.7.9.5

[PATCH V5 2/3] nvmem: add driver for ocotp in i.MX23 and i.MX28

[Stefan Wahren]

This patch brings read-only support for the On-Chip OTP cells
in the i.MX23 and i.MX28 processor. The driver implements the
new NVMEM provider API.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/nvmem/Kconfig     |   11 ++
 drivers/nvmem/Makefile    |    2 +
 drivers/nvmem/mxs-ocotp.c |  252 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 265 insertions(+)
 create mode 100644 drivers/nvmem/mxs-ocotp.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 8db2978..01ff8a6 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -36,4 +36,15 @@ config NVMEM_SUNXI_SID
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem_sunxi_sid.
 
+config NVMEM_MXS_OCOTP
+	tristate "Freescale MXS On-Chip OTP Memory Support"
+	depends on ARCH_MXS
+	help
+	  If you say Y here, you will get readonly access to the
+	  One Time Programmable memory pages that are stored
+	  on the Freescale i.MX23/i.MX28 processor.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nvmem-mxs-ocotp.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 4328b93..e9b6f3c 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -10,3 +10,5 @@ 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_MXS_OCOTP)	+= nvmem-mxs-ocotp.o
+nvmem-mxs-ocotp-y		:= mxs-ocotp.o
diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
new file mode 100644
index 0000000..9ee146b
--- /dev/null
+++ b/drivers/nvmem/mxs-ocotp.c
@@ -0,0 +1,252 @@
+/*
+ * Freescale MXS On-Chip OTP driver
+ *
+ * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>
+ *
+ * Based on the driver from Huang Shijie and Christoph G. Baumann
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/stmp_device.h>
+
+/* OCOTP registers and bits */
+
+#define BM_OCOTP_CTRL_RD_BANK_OPEN	BIT(12)
+#define BM_OCOTP_CTRL_ERROR		BIT(9)
+#define BM_OCOTP_CTRL_BUSY		BIT(8)
+
+#define OCOTP_TIMEOUT		10000
+#define OCOTP_DATA_OFFSET	0x20
+
+struct mxs_ocotp {
+	struct clk *clk;
+	void __iomem *base;
+	struct nvmem_device *nvmem;
+};
+
+static int mxs_ocotp_wait(struct mxs_ocotp *otp)
+{
+	int timeout = OCOTP_TIMEOUT;
+	unsigned int status = 0;
+
+	while (timeout--) {
+		status = readl(otp->base);
+
+		if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
+			break;
+
+		cpu_relax();
+	}
+
+	if (status & BM_OCOTP_CTRL_BUSY)
+		return -EBUSY;
+	else if (status & BM_OCOTP_CTRL_ERROR)
+		return -EIO;
+
+	return 0;
+}
+
+static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
+			  void *val, size_t val_size)
+{
+	struct mxs_ocotp *otp = context;
+	unsigned int offset = *(u32 *)reg;
+	u32 *buf = val;
+	int ret = 0;
+
+	writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
+
+	ret = mxs_ocotp_wait(otp);
+	if (ret)
+		return ret;
+
+	/* open OCOTP banks for read */
+	writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
+
+	/* approximately wait 33 hclk cycles */
+	udelay(1);
+
+	ret = mxs_ocotp_wait(otp);
+	if (ret)
+		goto close_banks;
+
+	while (val_size) {
+		if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
+			/* fill up non-data register */
+			*buf = 0;
+		} else {
+			*buf = readl(otp->base + offset);
+		}
+
+		buf++;
+		val_size--;
+		offset += reg_size;
+	}
+
+close_banks:
+	/* close banks for power saving */
+	writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
+
+	return ret;
+}
+
+static int mxs_ocotp_write(void *context, const void *data, size_t count)
+{
+	/* We don't want to support writing */
+	return 0;
+}
+
+static bool mxs_ocotp_writeable_reg(struct device *dev, unsigned int reg)
+{
+	return false;
+}
+
+static struct nvmem_config ocotp_config = {
+	.name = "mxs-ocotp",
+	.owner = THIS_MODULE,
+};
+
+static const struct regmap_range imx23_ranges[] = {
+	regmap_reg_range(OCOTP_DATA_OFFSET, 0x210),
+};
+
+static const struct regmap_access_table imx23_access = {
+	.yes_ranges = imx23_ranges,
+	.n_yes_ranges = ARRAY_SIZE(imx23_ranges),
+};
+
+static const struct regmap_range imx28_ranges[] = {
+	regmap_reg_range(OCOTP_DATA_OFFSET, 0x290),
+};
+
+static const struct regmap_access_table imx28_access = {
+	.yes_ranges = imx28_ranges,
+	.n_yes_ranges = ARRAY_SIZE(imx28_ranges),
+};
+
+static struct regmap_bus mxs_ocotp_bus = {
+	.read = mxs_ocotp_read,
+	.write = mxs_ocotp_write, /* make regmap_init() happy */
+	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+static struct regmap_config mxs_ocotp_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 16,
+	.writeable_reg = mxs_ocotp_writeable_reg,
+};
+
+static const struct of_device_id mxs_ocotp_match[] = {
+	{ .compatible = "fsl,imx23-ocotp", .data = &imx23_access },
+	{ .compatible = "fsl,imx28-ocotp", .data = &imx28_access },
+	{ /* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
+
+static int mxs_ocotp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mxs_ocotp *otp;
+	struct resource *res;
+	const struct of_device_id *match;
+	struct regmap *regmap;
+	const struct regmap_access_table *access;
+	int ret;
+
+	match = of_match_device(dev->driver->of_match_table, dev);
+	if (!match || !match->data)
+		return -EINVAL;
+
+	otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
+	if (!otp)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	otp->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(otp->base))
+		return PTR_ERR(otp->base);
+
+	otp->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(otp->clk))
+		return PTR_ERR(otp->clk);
+
+	ret = clk_prepare(otp->clk);
+	if (ret < 0) {
+		dev_err(dev, "failed to prepare clk: %d\n", ret);
+		return ret;
+	}
+
+	access = match->data;
+	mxs_ocotp_config.rd_table = access;
+	mxs_ocotp_config.max_register = access->yes_ranges[0].range_max;
+
+	regmap = devm_regmap_init(dev, &mxs_ocotp_bus, otp, &mxs_ocotp_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "regmap init failed\n");
+		ret = PTR_ERR(regmap);
+		goto err_clk;
+	}
+
+	ocotp_config.dev = dev;
+	otp->nvmem = nvmem_register(&ocotp_config);
+	if (IS_ERR(otp->nvmem)) {
+		ret = PTR_ERR(otp->nvmem);
+		goto err_clk;
+	}
+
+	platform_set_drvdata(pdev, otp);
+
+	return 0;
+
+err_clk:
+	clk_unprepare(otp->clk);
+
+	return ret;
+}
+
+static int mxs_ocotp_remove(struct platform_device *pdev)
+{
+	struct mxs_ocotp *otp = platform_get_drvdata(pdev);
+
+	clk_unprepare(otp->clk);
+
+	return nvmem_unregister(otp->nvmem);
+}
+
+static struct platform_driver mxs_ocotp_driver = {
+	.probe = mxs_ocotp_probe,
+	.remove = mxs_ocotp_remove,
+	.driver = {
+		.name = "mxs-ocotp",
+		.of_match_table = mxs_ocotp_match,
+	},
+};
+
+module_platform_driver(mxs_ocotp_driver);
+MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
+MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
+MODULE_LICENSE("GPL");
-- 
1.7.9.5

[PATCH V5 2/3] nvmem: add driver for ocotp in i.MX23 and i.MX28

[Srinivas Kandagatla]

Hi Stefan,

few nits.

On 11/08/15 14:30, Stefan Wahren wrote:
> This patch brings read-only support for the On-Chip OTP cells
> in the i.MX23 and i.MX28 processor. The driver implements the
> new NVMEM provider API.
>
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
>   drivers/nvmem/Kconfig     |   11 ++
>   drivers/nvmem/Makefile    |    2 +
>   drivers/nvmem/mxs-ocotp.c |  252 +++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 265 insertions(+)
>   create mode 100644 drivers/nvmem/mxs-ocotp.c
>
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 8db2978..01ff8a6 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -36,4 +36,15 @@ config NVMEM_SUNXI_SID
>   	  This driver can also be built as a module. If so, the module
>   	  will be called nvmem_sunxi_sid.
>
> +config NVMEM_MXS_OCOTP
> +	tristate "Freescale MXS On-Chip OTP Memory Support"
> +	depends on ARCH_MXS

Adding COMPILE_TEST here would enable the driver to be compile checked 
on buildrobots.

> +	help
> +	  If you say Y here, you will get readonly access to the
> +	  One Time Programmable memory pages that are stored
> +	  on the Freescale i.MX23/i.MX28 processor.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called nvmem-mxs-ocotp.
> +
>   endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 4328b93..e9b6f3c 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -10,3 +10,5 @@ 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_MXS_OCOTP)	+= nvmem-mxs-ocotp.o
> +nvmem-mxs-ocotp-y		:= mxs-ocotp.o
> diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
> new file mode 100644
> index 0000000..9ee146b
> --- /dev/null
> +++ b/drivers/nvmem/mxs-ocotp.c
> @@ -0,0 +1,252 @@
> +/*
> + * Freescale MXS On-Chip OTP driver
> + *
> + * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>
> + *
> + * Based on the driver from Huang Shijie and Christoph G. Baumann
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * 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/clk.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
??
> +#include <linux/nvmem-provider.h>
> +#include <linux/of_address.h>
??
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/stmp_device.h>
> +
> +/* OCOTP registers and bits */
> +
> +#define BM_OCOTP_CTRL_RD_BANK_OPEN	BIT(12)
> +#define BM_OCOTP_CTRL_ERROR		BIT(9)
> +#define BM_OCOTP_CTRL_BUSY		BIT(8)
> +
> +#define OCOTP_TIMEOUT		10000
> +#define OCOTP_DATA_OFFSET	0x20
> +
> +struct mxs_ocotp {
> +	struct clk *clk;
> +	void __iomem *base;
> +	struct nvmem_device *nvmem;
> +};
> +
> +static int mxs_ocotp_wait(struct mxs_ocotp *otp)
> +{
> +	int timeout = OCOTP_TIMEOUT;
> +	unsigned int status = 0;
> +
> +	while (timeout--) {
> +		status = readl(otp->base);
> +
> +		if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
> +			break;
> +
> +		cpu_relax();
> +	}
> +
> +	if (status & BM_OCOTP_CTRL_BUSY)
> +		return -EBUSY;
> +	else if (status & BM_OCOTP_CTRL_ERROR)
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
> +			  void *val, size_t val_size)
> +{
> +	struct mxs_ocotp *otp = context;
> +	unsigned int offset = *(u32 *)reg;
> +	u32 *buf = val;
> +	int ret = 0;
> +
> +	writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
> +
> +	ret = mxs_ocotp_wait(otp);
> +	if (ret)
> +		return ret;
> +
> +	/* open OCOTP banks for read */
> +	writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
> +
> +	/* approximately wait 33 hclk cycles */
> +	udelay(1);
> +
> +	ret = mxs_ocotp_wait(otp);
> +	if (ret)
> +		goto close_banks;
> +
> +	while (val_size) {
> +		if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
> +			/* fill up non-data register */
> +			*buf = 0;
> +		} else {
> +			*buf = readl(otp->base + offset);
> +		}
> +
> +		buf++;
> +		val_size--;
> +		offset += reg_size;
> +	}
> +
> +close_banks:
> +	/* close banks for power saving */
> +	writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
> +
> +	return ret;
> +}
> +
> +static int mxs_ocotp_write(void *context, const void *data, size_t count)
> +{
> +	/* We don't want to support writing */
> +	return 0;
> +}
> +
> +static bool mxs_ocotp_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	return false;
> +}
> +
> +static struct nvmem_config ocotp_config = {
> +	.name = "mxs-ocotp",
> +	.owner = THIS_MODULE,
> +};
> +
> +static const struct regmap_range imx23_ranges[] = {
> +	regmap_reg_range(OCOTP_DATA_OFFSET, 0x210),
> +};
> +
> +static const struct regmap_access_table imx23_access = {
> +	.yes_ranges = imx23_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(imx23_ranges),
> +};
> +
> +static const struct regmap_range imx28_ranges[] = {
> +	regmap_reg_range(OCOTP_DATA_OFFSET, 0x290),
> +};
> +
> +static const struct regmap_access_table imx28_access = {
> +	.yes_ranges = imx28_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(imx28_ranges),
> +};
> +
> +static struct regmap_bus mxs_ocotp_bus = {
> +	.read = mxs_ocotp_read,
> +	.write = mxs_ocotp_write, /* make regmap_init() happy */
> +	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
> +	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
> +};
> +
> +static struct regmap_config mxs_ocotp_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 16,
> +	.writeable_reg = mxs_ocotp_writeable_reg,
> +};
> +
> +static const struct of_device_id mxs_ocotp_match[] = {
> +	{ .compatible = "fsl,imx23-ocotp", .data = &imx23_access },
> +	{ .compatible = "fsl,imx28-ocotp", .data = &imx28_access },
> +	{ /* sentinel */},
> +};
> +MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
> +
> +static int mxs_ocotp_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct mxs_ocotp *otp;
> +	struct resource *res;
> +	const struct of_device_id *match;
> +	struct regmap *regmap;
> +	const struct regmap_access_table *access;
> +	int ret;
> +
> +	match = of_match_device(dev->driver->of_match_table, dev);
> +	if (!match || !match->data)
> +		return -EINVAL;
> +
> +	otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
> +	if (!otp)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	otp->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(otp->base))
> +		return PTR_ERR(otp->base);
> +
> +	otp->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(otp->clk))
> +		return PTR_ERR(otp->clk);
> +
> +	ret = clk_prepare(otp->clk);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to prepare clk: %d\n", ret);
> +		return ret;
> +	}

Clk prepare will not really enable the clock, and I dont see a call to 
clk_enable() anywhere in this driver.

I dont see the point?

> +
> +	access = match->data;
> +	mxs_ocotp_config.rd_table = access;
> +	mxs_ocotp_config.max_register = access->yes_ranges[0].range_max;
> +
> +	regmap = devm_regmap_init(dev, &mxs_ocotp_bus, otp, &mxs_ocotp_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(dev, "regmap init failed\n");
> +		ret = PTR_ERR(regmap);
> +		goto err_clk;
> +	}
> +
> +	ocotp_config.dev = dev;
> +	otp->nvmem = nvmem_register(&ocotp_config);
> +	if (IS_ERR(otp->nvmem)) {
> +		ret = PTR_ERR(otp->nvmem);
> +		goto err_clk;
> +	}
> +
> +	platform_set_drvdata(pdev, otp);
> +
> +	return 0;
> +
> +err_clk:
> +	clk_unprepare(otp->clk);
> +
> +	return ret;
> +}
> +
> +static int mxs_ocotp_remove(struct platform_device *pdev)
> +{
> +	struct mxs_ocotp *otp = platform_get_drvdata(pdev);
> +
> +	clk_unprepare(otp->clk);
> +
> +	return nvmem_unregister(otp->nvmem);
> +}
> +
> +static struct platform_driver mxs_ocotp_driver = {
> +	.probe = mxs_ocotp_probe,
> +	.remove = mxs_ocotp_remove,
> +	.driver = {
> +		.name = "mxs-ocotp",
> +		.of_match_table = mxs_ocotp_match,
> +	},
> +};
> +
> +module_platform_driver(mxs_ocotp_driver);
> +MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
> +MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
> +MODULE_LICENSE("GPL");

GPL v2??

>

[PATCH V5 3/3] ARM: mxs: enable ocotp for i.MX23 and i.MX28

[Stefan Wahren]

This patch enables On Chip OTP support for i.MX23 and i.MX28 SoCs,
but keeps the old compatible string.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 arch/arm/boot/dts/imx23.dtsi |    7 +++++--
 arch/arm/boot/dts/imx28.dtsi |    7 +++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/imx23.dtsi b/arch/arm/boot/dts/imx23.dtsi
index b995333..0541563 100644
--- a/arch/arm/boot/dts/imx23.dtsi
+++ b/arch/arm/boot/dts/imx23.dtsi
@@ -383,9 +383,12 @@
 			};
 
 			ocotp at 8002c000 {
-				compatible = "fsl,ocotp";
+				compatible = "fsl,imx23-ocotp", "fsl,ocotp";
+				#address-cells = <1>;
+				#size-cells = <1>;
 				reg = <0x8002c000 0x2000>;
-				status = "disabled";
+				clocks = <&clks 15>;
+				status = "okay";
 			};
 
 			axi-ahb at 8002e000 {
diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index 4e073e8..648d790 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -936,9 +936,12 @@
 			};
 
 			ocotp: ocotp at 8002c000 {
-				compatible = "fsl,ocotp";
+				compatible = "fsl,imx28-ocotp", "fsl,ocotp";
+				#address-cells = <1>;
+				#size-cells = <1>;
 				reg = <0x8002c000 0x2000>;
-				status = "disabled";
+				clocks = <&clks 25>;
+				status = "okay";
 			};
 
 			axi-ahb at 8002e000 {
-- 
1.7.9.5

[PATCH V5 0/3] nvmem: add ocotp support for i.MX23 and i.MX28

[Marek Vasut]

On Tuesday, August 11, 2015 at 03:30:15 PM, Stefan Wahren wrote:
> This patch series brings read-only support for the On-Chip OTP cells
> in the i.MX23 and i.MX28 processor.
> 
> changes in V5:
> - rebase to char-misc-next
> - add nvmem prefix to module name
> - set status in dtsi files
> 
> changes in V4:
> - rename fsl_ocotp.c to mxs-ocotp.c
> - adapt driver to use NVMEM framework V7
> - take care of hbus clock
> - increase too small timeout
> - implement a wait function
> - use defines from stmp_device.h
> - remove owner init
> - more code cleanup
> 
> changes in V3:
> - drop write support
> - take care of i.MX23 which has less registers
> - drop unnecessary header file
> - move static variables into driver data
> - add devicetree probing
> - fix missing bank closing in error case
> - use kobj from platform device for sysfs
> - add SYSFS to Kconfig
> - add binding file
> - code cleanup
> 
> Stefan Wahren (3):
>   DT: nvmem: add binding for mxs-ocotp
>   nvmem: add driver for ocotp in i.MX23 and i.MX28
>   ARM: mxs: enable ocotp for i.MX23 and i.MX28
> 
>  .../devicetree/bindings/nvmem/mxs-ocotp.txt        |   24 ++
>  arch/arm/boot/dts/imx23.dtsi                       |    7 +-
>  arch/arm/boot/dts/imx28.dtsi                       |    7 +-
>  drivers/nvmem/Kconfig                              |   11 +
>  drivers/nvmem/Makefile                             |    2 +
>  drivers/nvmem/mxs-ocotp.c                          |  252
> ++++++++++++++++++++ 6 files changed, 299 insertions(+), 4 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/nvmem/mxs-ocotp.txt
>  create mode 100644 drivers/nvmem/mxs-ocotp.c

Very nice, other than the comments from Srinivas, you can add my

Reviewed-by: Marek Vasut <marex@denx.de>

Best regards,
Marek Vasut