driver: brcm: add RNG driver

Signed-off-by: Bharat Gooty <bharat.gooty@broadcom.com>
Change-Id: I490d7e4d49bd9f5a62d343a264a1e14c2066ceca

drivers/brcm/rng.c

+/*
+ * Copyright (c) 2017 - 2020, Broadcom
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <common/debug.h>
+#include <drivers/delay_timer.h>
+#include <lib/mmio.h>
+#include <platform_def.h>
+
+#define RNG_CTRL_REG		(RNG_BASE_ADDR + 0x00)
+#define RNG_CTRL_MASK		0x00001FFF
+#define RNG_CTRL_ENABLE		0x00000001
+#define RNG_CTRL_DISABLE	0x00000000
+
+#define RNG_SOFT_RESET_REG	(RNG_BASE_ADDR + 0x04)
+#define RNG_SOFT_RESET_MASK	0x00000001
+
+#define RNG_FIFO_DATA_REG	(RNG_BASE_ADDR + 0x20)
+
+#define RNG_FIFO_COUNT_REG	(RNG_BASE_ADDR + 0x24)
+#define RNG_FIFO_COUNT_MASK	0x000000FF
+
+#define RNG_FIFO_WORDS_MAX	16
+#define MAX_WAIT_COUNT_50US	20000
+
+
+static void rng_reset(void)
+{
+	/* Disable RBG */
+	mmio_clrbits_32(RNG_CTRL_REG, RNG_CTRL_MASK);
+
+	/* Reset RNG and RBG */
+	mmio_setbits_32(RNG_SOFT_RESET_REG, RNG_SOFT_RESET_MASK);
+
+	/* Take all out of reset */
+	mmio_clrbits_32(RNG_SOFT_RESET_REG, RNG_SOFT_RESET_MASK);
+}
+
+static void rng_enable(void)
+{
+	/* Setup RNG. */
+	mmio_clrsetbits_32(RNG_CTRL_REG, RNG_CTRL_MASK, RNG_CTRL_ENABLE);
+}
+
+int rng_init(void)
+{
+	rng_reset();
+
+	rng_enable();
+
+	return 0;
+}
+
+int rng_read(uint32_t *p_out, uint32_t *words_read)
+{
+	uint32_t available_words;
+	uint32_t i;
+	uint32_t word_processed = 0;
+	uint32_t wait_count = MAX_WAIT_COUNT_50US;
+
+	if (*words_read == 0) {
+		ERROR("RNG Parameter: No word requested\n");
+		return -1;
+	}
+
+	do {
+		available_words = mmio_read_32(RNG_FIFO_COUNT_REG);
+		available_words &= RNG_FIFO_COUNT_MASK;
+
+		if (available_words != 0) {
+			available_words = MIN(available_words,
+					*words_read - word_processed);
+
+			for (i = 0; i < available_words; i++)
+				p_out[word_processed + i] =
+					mmio_read_32(RNG_FIFO_DATA_REG);
+			word_processed += available_words;
+		} else {
+			udelay(50);
+		}
+
+		if (word_processed == *words_read)
+			break;
+
+	} while (--wait_count);
+
+	if (word_processed != *words_read) {
+		ERROR("RNG Timeout: requested %d word(s) got %d\n",
+				*words_read, word_processed);
+		*words_read = word_processed;
+		return -1;
+	}
+
+	return 0;
+}

plat/brcm/board/common/board_common.mk

@@ -133,6 +133,12 @@ PLAT_BL_COMMON_SOURCES	+=	plat/brcm/common/brcm_common.c \
 				plat/brcm/board/common/sbl_util.c \
 				drivers/arm/sp805/sp805.c
 
+# Add RNG driver
+DRIVER_RNG_ENABLE := 1
+ifeq (${DRIVER_RNG_ENABLE},1)
+PLAT_BL_COMMON_SOURCES	+=	drivers/brcm/rng.c
+endif
+
 # Add eMMC driver
 ifeq (${DRIVER_EMMC_ENABLE},1)
 $(eval $(call add_define,DRIVER_EMMC_ENABLE))