[PATCH V6 2/3] nvmem: add driver for ocotp in i.MX23 and i.MX28

Stefan Wahren
2015-08-12T22:21:55Z

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-eS4NqCHxEME@public.gmane.org>
Reviewed-by: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
---
drivers/nvmem/Kconfig | 11 ++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/mxs-ocotp.c | 257 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 270 insertions(+)
create mode 100644 drivers/nvmem/mxs-ocotp.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 8db2978..a7b43b9 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 || 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.
+
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..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-eS4NqCHxEME@public.gmane.org>
+ *
+ * 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-eS4NqCHxEME@public.gmane.org>");
+MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5