nvmem: add driver for ocotp in i.MX23 and i.MX28

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>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 208a1cb..a6d8053 100644 (file)
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -25,6 +25,17 @@ config NVMEM_IMX_OCOTP
          This driver can also be built as a module. If so, the module
          will be called nvmem-imx-ocotp.
 
+config NVMEM_MXS_OCOTP
+       tristate "Freescale MXS On-Chip OTP Memory Support"
+       depends on ARCH_MXS || COMPILE_TEST
+       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.
+
 config QCOM_QFPROM
        tristate "QCOM QFPROM Support"
        depends on ARCH_QCOM || COMPILE_TEST

diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 2ddf0e8..9322116 100644 (file)
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -8,6 +8,8 @@ nvmem_core-y                    := core.o
 # Devices
 obj-$(CONFIG_NVMEM_IMX_OCOTP)  += nvmem-imx-ocotp.o
 nvmem-imx-ocotp-y              := imx-ocotp.o
+obj-$(CONFIG_NVMEM_MXS_OCOTP)  += nvmem-mxs-ocotp.o
+nvmem-mxs-ocotp-y              := mxs-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/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
new file mode 100644 (file)
index 0000000..8ba19bb
--- /dev/null
+++ b/drivers/nvmem/mxs-ocotp.c
@@ -0,0 +1,257 @@
+/*
+ * 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/nvmem-provider.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;
+
+       ret = clk_enable(otp->clk);
+       if (ret)
+               return ret;
+
+       writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
+
+       ret = mxs_ocotp_wait(otp);
+       if (ret)
+               goto disable_clk;
+
+       /* 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);
+
+disable_clk:
+       clk_disable(otp->clk);
+
+       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 v2");