dm: rng: Add random number generator(rng) uclass

Add a uclass for reading a random number seed from a random number
generator device.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

7 files changed, 73 insertions, 0 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 9d99ce0..e34a227 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -90,6 +90,8 @@ source "drivers/remoteproc/Kconfig"
 
 source "drivers/reset/Kconfig"
 
+source "drivers/rng/Kconfig"
+
 source "drivers/rtc/Kconfig"
 
 source "drivers/scsi/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index cb8c215..8eec4e8 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -116,4 +116,5 @@ obj-$(CONFIG_W1_EEPROM) += w1-eeprom/
 
 obj-$(CONFIG_MACH_PIC32) += ddr/microchip/
 obj-$(CONFIG_DM_HWSPINLOCK) += hwspinlock/
+obj-$(CONFIG_DM_RNG) += rng/
 endif
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
new file mode 100644
index 0000000..dd44cc0
--- /dev/null
+++ b/drivers/rng/Kconfig
@@ -0,0 +1,7 @@
+config DM_RNG
+	bool "Driver support for Random Number Generator devices"
+	depends on DM
+	help
+	  Enable driver model for random number generator(rng) devices.
+	  This interface is used to initialise the rng device and to
+	  read the random seed from the device.
diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
new file mode 100644
index 0000000..311705b
--- /dev/null
+++ b/drivers/rng/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (c) 2019, Linaro Limited
+#
+
+obj-$(CONFIG_DM_RNG) += rng-uclass.o
diff --git a/drivers/rng/rng-uclass.c b/drivers/rng/rng-uclass.c
new file mode 100644
index 0000000..b6af3b8
--- /dev/null
+++ b/drivers/rng/rng-uclass.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <rng.h>
+
+int dm_rng_read(struct udevice *dev, void *buffer, size_t size)
+{
+	const struct dm_rng_ops *ops = device_get_ops(dev);
+
+	if (!ops->read)
+		return -ENOSYS;
+
+	return ops->read(dev, buffer, size);
+}
+
+UCLASS_DRIVER(rng) = {
+	.name = "rng",
+	.id = UCLASS_RNG,
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index c1bab17..67f5d67 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -88,6 +88,7 @@ enum uclass_id {
 	UCLASS_REGULATOR,	/* Regulator device */
 	UCLASS_REMOTEPROC,	/* Remote Processor device */
 	UCLASS_RESET,		/* Reset controller device */
+	UCLASS_RNG,		/* Random Number Generator */
 	UCLASS_RTC,		/* Real time clock device */
 	UCLASS_SCSI,		/* SCSI device */
 	UCLASS_SERIAL,		/* Serial UART */
diff --git a/include/rng.h b/include/rng.h
new file mode 100644
index 0000000..d2c0f9a
--- /dev/null
+++ b/include/rng.h
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#if !defined _RNG_H_
+#define _RNG_H_
+
+struct udevice;
+
+/**
+ * dm_rng_read() - read a random number seed from the rng device
+ * @buffer:	input buffer to put the read random seed into
+ * @size:	number of bytes of random seed read
+ *
+ * Return: 0 if OK, -ve on error
+ */
+int dm_rng_read(struct udevice *dev, void *buffer, size_t size);
+
+/* struct dm_rng_ops - Operations for the hwrng uclass */
+struct dm_rng_ops {
+	/**
+	 * @read() - read a random number seed
+	 *
+	 * @data:	input buffer to read the random seed
+	 * @max:	total number of bytes to read
+	 *
+	 * Return: 0 if OK, -ve on error
+	 */
+	int (*read)(struct udevice *dev, void *data, size_t max);
+};
+
+#endif /* _RNG_H_ */