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Diffstat (limited to 'drivers/nvmem/mxs-ocotp.c')
-rw-r--r--drivers/nvmem/mxs-ocotp.c197
1 files changed, 197 insertions, 0 deletions
diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
new file mode 100644
index 0000000000..588ab56d75
--- /dev/null
+++ b/drivers/nvmem/mxs-ocotp.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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
+ */
+#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/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, unsigned int offset,
+ void *val, size_t bytes)
+{
+ struct mxs_ocotp *otp = context;
+ 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 (bytes) {
+ if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
+ /* fill up non-data register */
+ *buf++ = 0;
+ } else {
+ *buf++ = readl(otp->base + offset);
+ }
+
+ bytes -= 4;
+ offset += 4;
+ }
+
+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 struct nvmem_config ocotp_config = {
+ .name = "mxs-ocotp",
+ .stride = 16,
+ .word_size = 4,
+ .reg_read = mxs_ocotp_read,
+};
+
+struct mxs_data {
+ int size;
+};
+
+static const struct mxs_data imx23_data = {
+ .size = 0x220,
+};
+
+static const struct mxs_data imx28_data = {
+ .size = 0x2a0,
+};
+
+static const struct of_device_id mxs_ocotp_match[] = {
+ { .compatible = "fsl,imx23-ocotp", .data = &imx23_data },
+ { .compatible = "fsl,imx28-ocotp", .data = &imx28_data },
+ { /* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
+
+static void mxs_ocotp_action(void *data)
+{
+ clk_unprepare(data);
+}
+
+static int mxs_ocotp_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ const struct mxs_data *data;
+ struct mxs_ocotp *otp;
+ const struct of_device_id *match;
+ 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;
+
+ otp->base = devm_platform_ioremap_resource(pdev, 0);
+ 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;
+ }
+
+ ret = devm_add_action_or_reset(&pdev->dev, mxs_ocotp_action, otp->clk);
+ if (ret)
+ return ret;
+
+ data = match->data;
+
+ ocotp_config.size = data->size;
+ ocotp_config.priv = otp;
+ ocotp_config.dev = dev;
+ otp->nvmem = devm_nvmem_register(dev, &ocotp_config);
+ if (IS_ERR(otp->nvmem))
+ return PTR_ERR(otp->nvmem);
+
+ platform_set_drvdata(pdev, otp);
+
+ return 0;
+}
+
+static struct platform_driver mxs_ocotp_driver = {
+ .probe = mxs_ocotp_probe,
+ .driver = {
+ .name = "mxs-ocotp",
+ .of_match_table = mxs_ocotp_match,
+ },
+};
+
+module_platform_driver(mxs_ocotp_driver);
+MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");
+MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
+MODULE_LICENSE("GPL v2");