nvmem: imx-ocotp: Add i.MX6 OCOTP driver

This driver handles the i.MX On-Chip OTP Controller found in
i.MX6Q/D, i.MX6S/DL, i.MX6SL, and i.MX6SX SoCs. Currently it
just returns the values stored in the shadow registers.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 167 insertions, 0 deletions

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 1d4f2b4fe092..208a1cb6e4bf 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -14,6 +14,17 @@ menuconfig NVMEM
 
 if NVMEM
 
+config NVMEM_IMX_OCOTP
+        tristate "i.MX6 On-Chip OTP Controller support"
+        depends on SOC_IMX6
+        help
+          This is a driver for the On-Chip OTP Controller (OCOTP) available on
+          i.MX6 SoCs, providing access to 4 Kbits of one-time programmable
+          eFuses.
+
+          This driver can also be built as a module. If so, the module
+          will be called nvmem-imx-ocotp.
+
 config QCOM_QFPROM
         tristate "QCOM QFPROM Support"
         depends on ARCH_QCOM || COMPILE_TEST
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 3bdcfd4c7dd0..2ddf0e88af3c 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -6,6 +6,8 @@ obj-$(CONFIG_NVMEM)		+= nvmem_core.o
 nvmem_core-y                    := core.o
 
 # Devices
+obj-$(CONFIG_NVMEM_IMX_OCOTP)   += nvmem-imx-ocotp.o
+nvmem-imx-ocotp-y               := imx-ocotp.o
 obj-$(CONFIG_QCOM_QFPROM)       += nvmem_qfprom.o
 nvmem_qfprom-y                  := qfprom.o
 obj-$(CONFIG_NVMEM_SUNXI_SID)   += nvmem_sunxi_sid.o
diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
new file mode 100644
index 000000000000..b7971d410b60
--- /dev/null
+++ b/drivers/nvmem/imx-ocotp.c
@@ -0,0 +1,154 @@
+/*
+ * i.MX6 OCOTP fusebox driver
+ *
+ * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de>
+ *
+ * Based on the barebox ocotp driver,
+ * Copyright (c) 2010 Baruch Siach <baruch@tkos.co.il>,
+ *      Orex Computed Radiography
+ *
+ * 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.
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#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/regmap.h>
+#include <linux/slab.h>
+
+struct ocotp_priv {
+        struct device *dev;
+        void __iomem *base;
+        unsigned int nregs;
+};
+
+static int imx_ocotp_read(void *context, const void *reg, size_t reg_size,
+                          void *val, size_t val_size)
+{
+        struct ocotp_priv *priv = context;
+        unsigned int offset = *(u32 *)reg;
+        unsigned int count;
+        int i;
+        u32 index;
+
+        index = offset >> 2;
+        count = val_size >> 2;
+
+        if (count > (priv->nregs - index))
+                count = priv->nregs - index;
+
+        for (i = index; i < (index + count); i++) {
+                *(u32 *)val = readl(priv->base + 0x400 + i * 0x10);
+                val += 4;
+        }
+
+        return (i - index) * 4;
+}
+
+static int imx_ocotp_write(void *context, const void *data, size_t count)
+{
+        /* Not implemented */
+        return 0;
+}
+
+static struct regmap_bus imx_ocotp_bus = {
+        .read = imx_ocotp_read,
+        .write = imx_ocotp_write,
+        .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+        .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+static bool imx_ocotp_writeable_reg(struct device *dev, unsigned int reg)
+{
+        return false;
+}
+
+static struct regmap_config imx_ocotp_regmap_config = {
+        .reg_bits = 32,
+        .val_bits = 32,
+        .reg_stride = 4,
+        .writeable_reg = imx_ocotp_writeable_reg,
+        .name = "imx-ocotp",
+};
+
+static struct nvmem_config imx_ocotp_nvmem_config = {
+        .name = "imx-ocotp",
+        .read_only = true,
+        .owner = THIS_MODULE,
+};
+
+static const struct of_device_id imx_ocotp_dt_ids[] = {
+        { .compatible = "fsl,imx6q-ocotp",  (void *)128 },
+        { .compatible = "fsl,imx6sl-ocotp", (void *)32 },
+        { .compatible = "fsl,imx6sx-ocotp", (void *)128 },
+        { },
+};
+MODULE_DEVICE_TABLE(of, imx_ocotp_dt_ids);
+
+static int imx_ocotp_probe(struct platform_device *pdev)
+{
+        const struct of_device_id *of_id;
+        struct device *dev = &pdev->dev;
+        struct resource *res;
+        struct regmap *regmap;
+        struct ocotp_priv *priv;
+        struct nvmem_device *nvmem;
+
+        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        priv->base = devm_ioremap_resource(dev, res);
+        if (IS_ERR(priv->base))
+                return PTR_ERR(priv->base);
+
+        of_id = of_match_device(imx_ocotp_dt_ids, dev);
+        priv->nregs = (unsigned int)of_id->data;
+        imx_ocotp_regmap_config.max_register = 4 * priv->nregs - 4;
+
+        regmap = devm_regmap_init(dev, &imx_ocotp_bus, priv,
+                                  &imx_ocotp_regmap_config);
+        if (IS_ERR(regmap)) {
+                dev_err(dev, "regmap init failed\n");
+                return PTR_ERR(regmap);
+        }
+        imx_ocotp_nvmem_config.dev = dev;
+        nvmem = nvmem_register(&imx_ocotp_nvmem_config);
+        if (IS_ERR(nvmem))
+                return PTR_ERR(nvmem);
+
+        platform_set_drvdata(pdev, nvmem);
+
+        return 0;
+}
+
+static int imx_ocotp_remove(struct platform_device *pdev)
+{
+        struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+        return nvmem_unregister(nvmem);
+}
+
+static struct platform_driver imx_ocotp_driver = {
+        .probe  = imx_ocotp_probe,
+        .remove = imx_ocotp_remove,
+        .driver = {
+                .name   = "imx_ocotp",
+                .of_match_table = imx_ocotp_dt_ids,
+        },
+};
+module_platform_driver(imx_ocotp_driver);
+
+MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
+MODULE_DESCRIPTION("i.MX6 OCOTP fuse box driver");
+MODULE_LICENSE("GPL v2");