qti: Add RNG driver
This patch adds RNG driver and use it to generate random number for stack
protection.
Change-Id: I73d79e68d08b5aa902dc7fad48e17a03f996178d
Signed-off-by: Saurabh Gorecha <sgorecha@codeaurora.org>
diff --git a/plat/qti/common/src/qti_rng.c b/plat/qti/common/src/qti_rng.c
new file mode 100644
index 0000000..a904209
--- /dev/null
+++ b/plat/qti/common/src/qti_rng.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include <stddef.h>
+#include <stdint.h>
+
+#include <lib/mmio.h>
+
+#include <qti_rng_io.h>
+
+int qti_rng_get_data(uint8_t *out, uint32_t out_len)
+{
+ uint32_t tmp_rndm = 0;
+ uint32_t bytes_left = out_len;
+ int i = 0;
+
+ if (NULL == out || 0 == out_len) {
+ return -1;
+ }
+
+ /*
+ * RNG HW initialized at previous boot image.
+ * RNG clocks are expected to be ON.
+ */
+
+ do {
+ /* There is no data to read */
+ if ((mmio_read_32(SEC_PRNG_STATUS) &
+ SEC_PRNG_STATUS_DATA_AVAIL_BMSK) == 0) {
+ continue;
+ }
+
+ while ((tmp_rndm = mmio_read_32(SEC_PRNG_DATA_OUT)) == 0) {
+ ;
+ }
+
+ for (i = 0; i < 4; i++) {
+ *out = (uint8_t) (tmp_rndm >> (8 * i));
+
+ out++;
+ bytes_left--;
+
+ if (bytes_left == 0) {
+ break;
+ }
+ }
+
+ } while (bytes_left != 0);
+
+ return 0;
+}