1 files changed, 80 insertions, 0 deletions
diff --git a/drivers/mfd/wm831x-otp.c b/drivers/mfd/wm831x-otp.c
new file mode 100644
index 000000000..25f5d9fe3
--- /dev/null
+++ b/drivers/mfd/wm831x-otp.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * wm831x-otp.c  --  OTP for Wolfson WM831x PMICs
+ *
+ * Copyright 2009 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/delay.h>
+#include <linux/mfd/core.h>
+#include <linux/random.h>
+
+#include <linux/mfd/wm831x/core.h>
+#include <linux/mfd/wm831x/otp.h>
+
+/* In bytes */
+#define WM831X_UNIQUE_ID_LEN 16
+
+/* Read the unique ID from the chip into id */
+static int wm831x_unique_id_read(struct wm831x *wm831x, char *id)
+{
+	int i, val;
+
+	for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) {
+		val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i);
+		if (val < 0)
+			return val;
+
+		id[i * 2]       = (val >> 8) & 0xff;
+		id[(i * 2) + 1] = val & 0xff;
+	}
+
+	return 0;
+}
+
+static ssize_t unique_id_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct wm831x *wm831x = dev_get_drvdata(dev);
+	int rval;
+	char id[WM831X_UNIQUE_ID_LEN];
+
+	rval = wm831x_unique_id_read(wm831x, id);
+	if (rval < 0)
+		return 0;
+
+	return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id);
+}
+
+static DEVICE_ATTR_RO(unique_id);
+
+int wm831x_otp_init(struct wm831x *wm831x)
+{
+	char uuid[WM831X_UNIQUE_ID_LEN];
+	int ret;
+
+	ret = device_create_file(wm831x->dev, &dev_attr_unique_id);
+	if (ret != 0)
+		dev_err(wm831x->dev, "Unique ID attribute not created: %d\n",
+			ret);
+
+	ret = wm831x_unique_id_read(wm831x, uuid);
+	if (ret == 0)
+		add_device_randomness(uuid, sizeof(uuid));
+	else
+		dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret);
+
+	return ret;
+}
+
+void wm831x_otp_exit(struct wm831x *wm831x)
+{
+	device_remove_file(wm831x->dev, &dev_attr_unique_id);
+}
+