UPSTREAM: 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>
(cherry picked from commit a2487684003b0bc380955e1a38cdd71da3ca4366)

Change-Id: Ife2287132db695181d663653f2ceaab0e343b41f
Signed-off-by: Lin Jinhan <troy.lin@rock-chips.com>

drivers/Kconfig

@@ -18,6 +18,8 @@ source "drivers/cpu/Kconfig"
 
 source "drivers/crypto/Kconfig"
 
+source "drivers/rng/Kconfig"
+
 source "drivers/ddr/Kconfig"
 
 source "drivers/demo/Kconfig"

drivers/Makefile

@@ -5,6 +5,7 @@
 obj-$(CONFIG_$(SPL_TPL_)CLK) += clk/
 obj-$(CONFIG_$(SPL_TPL_)DM) += core/
 obj-$(CONFIG_$(SPL_TPL_)DM_CRYPTO) += crypto/
+obj-$(CONFIG_$(SPL_TPL_)DM_RNG) += rng/
 obj-$(CONFIG_$(SPL_TPL_)DRIVERS_MISC_SUPPORT) += misc/ sysreset/ firmware/
 obj-$(CONFIG_$(SPL_TPL_)I2C_SUPPORT) += i2c/
 obj-$(CONFIG_$(SPL_TPL_)LED) += led/

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.

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

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,
+};

include/dm/uclass-id.h

@@ -109,6 +109,7 @@ enum uclass_id {
 	UCLASS_MDIO,		/* MDIO bus */
 	UCLASS_EBC,		/* EBC Controller for eink screen */
 	UCLASS_EINK_DISPLAY,	/* EINK screen display driver */
+	UCLASS_RNG,		/* Random Number Generator */
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,
 };

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_ */