Signed-off-by: Pankaj Dev <redacted>
Signed-off-by: Lee Jones <redacted>
---
 drivers/char/hw_random/Kconfig  |  10 +++
 drivers/char/hw_random/Makefile |   1 +
 drivers/char/hw_random/st-rng.c | 142 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 153 insertions(+)
 create mode 100644 drivers/char/hw_random/st-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index f48cf11..bb6cb77 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig

@@ -346,6 +346,16 @@ config HW_RANDOM_MSM

          If unsure, say Y.

+config HW_RANDOM_ST
+       tristate "ST Microelectronics HW Random Number Generator support"
+       depends on HW_RANDOM && ARCH_STI
+       ---help---
+         This driver provides kernel-side support for the Random Number
+         Generator hardware found on STi series of SoCs.
+
+         To compile this driver as a module, choose M here: the
+         module will be called st-rng.
+
 config HW_RANDOM_XGENE
        tristate "APM X-Gene True Random Number Generator (TRNG) support"
        depends on HW_RANDOM && ARCH_XGENE

diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 055bb01..8bcfb45 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile

@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
 obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
 obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
+obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
 obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o

diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
new file mode 100644
index 0000000..717a831
--- /dev/null
+++ b/drivers/char/hw_random/st-rng.c

@@ -0,0 +1,142 @@
+/*
+ * ST Random Number Generator Driver ST's Platforms
+ *
+ * Author: Pankaj Dev: <pankaj.dev@st.com>
+ *         Lee Jones <lee.jones@linaro.org>
+ *
+ * Copyright (C) 2015 STMicroelectronics (R&D) Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+/* Registers */
+#define ST_RNG_STATUS_REG              0x20
+#define ST_RNG_DATA_REG                        0x24
+
+/* Registers fields */
+#define ST_RNG_STATUS_BAD_SEQUENCE     BIT(0)
+#define ST_RNG_STATUS_BAD_ALTERNANCE   BIT(1)
+#define ST_RNG_STATUS_FIFO_FULL                BIT(5)
+
+#define ST_RNG_FIFO_SIZE               8
+#define ST_RNG_SAMPLE_SIZE             2 /* 2 Byte (16bit) samples */
+
+/* Samples are available every 0.667us, which we round to 1us */
+#define ST_RNG_FILL_FIFO_TIMEOUT   (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE))
+
+struct st_rng_data {
+       void __iomem    *base;
+       struct clk      *clk;
+       struct hwrng    ops;
+};
+
+static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+       struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
+       u32 status;
+       int i;
+
+       if (max < sizeof(u16))
+               return -EINVAL;
+
+       /* Wait until FIFO is full - max 4uS*/
+       for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
+               status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
+               if (status & ST_RNG_STATUS_FIFO_FULL)
+                       break;
+               udelay(1);
+       }
+
+       if (i == ST_RNG_FILL_FIFO_TIMEOUT)
+               return 0;
+
+       for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
+               *(u16 *)(data + i) =
+                       readl_relaxed(ddata->base + ST_RNG_DATA_REG);