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>

plat/qti/common/inc/qti_rng.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef QTI_RNG_H
+#define QTI_RNG_H
+
+#include <stdinit.h>
+
+int qti_rng_get_data(uint8_t *out, uint32_t out_len);
+
+#endif /* QTI_RNG_H */

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;
+}

plat/qti/common/src/qti_stack_protector.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,16 +9,18 @@
 
 #include <platform.h>
 #include <platform_def.h>
+#include <qti_rng.h>
 #include <qtiseclib_interface.h>
 
 u_register_t plat_get_stack_protector_canary(void)
 {
 	u_register_t random = 0x0;
 
-	/* get random data , the below API doesn't return random = 0 in success
-	 * case */
-	qtiseclib_prng_get_data((uint8_t *) &random, sizeof(random));
-	assert(0x0 != random);
+	/*
+	 * get random data , the below API doesn't return random = 0 on success
+	 */
+	qti_rng_get_data((uint8_t *) &random, sizeof(random));
+	assert(random != 0x0);
 
 	return random;
 }

plat/qti/qtiseclib/inc/qtiseclib_interface.h

@@ -63,7 +63,6 @@ void qtiseclib_kryo4_silver_reset_asm(void);
 void qtiseclib_bl31_platform_setup(void);
 void qtiseclib_invoke_isr(uint32_t irq, void *handle);
 void qtiseclib_panic(void);
-int qtiseclib_prng_get_data(uint8_t *out, uint32_t out_len);
 
 int qtiseclib_mem_assign(const memprot_info_t *mem_info,
 			 uint32_t mem_info_list_cnt,

plat/qti/qtiseclib/src/qtiseclib_interface_stub.c

@@ -67,17 +67,6 @@ void qtiseclib_panic(void)
 {
 }
 
-int qtiseclib_prng_get_data(uint8_t *out, uint32_t out_len)
-{
-	/* fill dummy data to avoid assert and print
-	 * stub implementation in setup call
-	 */
-	for (int i = 0; i < out_len; i++) {
-		out[i] = 0x11;
-	}
-	return 0;
-}
-
 int
 qtiseclib_mem_assign(const memprot_info_t *mem_info,
 		     uint32_t mem_info_list_cnt,

plat/qti/sc7180/inc/qti_rng_io.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef QTI_RNG_IO_H
+#define QTI_RNG_IO_H
+
+#define SEC_PRNG_STATUS			0x00791004
+#define SEC_PRNG_STATUS_DATA_AVAIL_BMSK	0x1
+#define SEC_PRNG_DATA_OUT		0x00791000
+
+
+#endif /* QTI_RNG_IO_H */
+

plat/qti/sc7180/platform.mk

@@ -59,6 +59,7 @@ QTI_BL31_SOURCES	:=	$(QTI_PLAT_PATH)/common/src/$(ARCH)/qti_helpers.S	\
 				$(QTI_PLAT_PATH)/common/src/qti_syscall.c		\
 				$(QTI_PLAT_PATH)/common/src/qti_topology.c		\
 				$(QTI_PLAT_PATH)/common/src/qti_pm.c			\
+				$(QTI_PLAT_PATH)/common/src/qti_rng.c			\
 				$(QTI_PLAT_PATH)/qtiseclib/src/qtiseclib_cb_interface.c	\