common: move chip agnostic trng code from stm32 to common

Making this change causes common trng functions to move memory
locations. This change only affects fingerprint (FPMCU) boards

BUG=b:280889889
TEST=make BOARD=bloonchipper, CONFIG_CMD_RAND enabled in board.h
     ALLOW_CONFIG=1 ./util/compare_build.sh -b all
 => All boards match, except the following Fingerprint boards:
        bloonchipper
	dartmonkey
	hatch_fp
	nami_fp
	nocturne_fp
	nucleo-dartmonkey

Change-Id: I4dbb5e255be0f61eb7b446af4565bea487c08e52
Signed-off-by: David Cross <davidmcross@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4507892
Reviewed-by: Bobby Casey <bobbycasey@google.com>

5 files changed, 97 insertions, 71 deletions

diff --git a/chip/host/trng.c b/chip/host/trng.c
index d0def66277..f67dd6c4db 100644
--- a/chip/host/trng.c
+++ b/chip/host/trng.c
@@ -31,6 +31,11 @@ test_mockable void trng_exit(void)
 {
 }
 
+test_mockable uint32_t trng_rand(void)
+{
+	return (uint32_t)rand_r(&seed);
+}
+
 test_mockable void trng_rand_bytes(void *buffer, size_t len)
 {
 	uint8_t *b, *end;
diff --git a/chip/stm32/trng.c b/chip/stm32/trng.c
index 67d3700cf1..63641741d3 100644
--- a/chip/stm32/trng.c
+++ b/chip/stm32/trng.c
@@ -16,7 +16,7 @@
 #include "trng.h"
 #include "util.h"
 
-static uint32_t trng_rand(void)
+uint32_t trng_rand(void)
 {
 	int tries = 300;
 	/* Wait for a valid random number */
@@ -29,25 +29,6 @@ static uint32_t trng_rand(void)
 	return STM32_RNG_DR;
 }
 
-test_mockable void trng_rand_bytes(void *buffer, size_t len)
-{
-	while (len) {
-		uint32_t number = trng_rand();
-		size_t cnt = 4;
-		/* deal with the lack of alignment guarantee in the API */
-		uintptr_t align = (uintptr_t)buffer & 3;
-
-		if (len < 4 || align) {
-			cnt = MIN(4 - align, len);
-			memcpy(buffer, &number, cnt);
-		} else {
-			*(uint32_t *)buffer = number;
-		}
-		len -= cnt;
-		buffer += cnt;
-	}
-}
-
 test_mockable void trng_init(void)
 {
 #ifdef CHIP_FAMILY_STM32L4
@@ -97,53 +78,3 @@ test_mockable void trng_exit(void)
 	/* Nothing to do */
 #endif
 }
-
-#if defined(CONFIG_CMD_RAND)
-/*
- * We want to avoid accidentally exposing debug commands in RO since we can't
- * update RO once in production.
- */
-#if defined(SECTION_IS_RW)
-static int command_rand(int argc, const char **argv)
-{
-	uint8_t data[32];
-	char str_buf[hex_str_buf_size(sizeof(data))];
-
-	trng_init();
-	trng_rand_bytes(data, sizeof(data));
-	trng_exit();
-
-	snprintf_hex_buffer(str_buf, sizeof(str_buf),
-			    HEX_BUF(data, sizeof(data)));
-	ccprintf("rand %s\n", str_buf);
-
-	return EC_SUCCESS;
-}
-DECLARE_CONSOLE_COMMAND(rand, command_rand, NULL,
-			"Output random bytes to console.");
-
-static enum ec_status host_command_rand(struct host_cmd_handler_args *args)
-{
-	const struct ec_params_rand_num *p = args->params;
-	struct ec_response_rand_num *r = args->response;
-	uint16_t num_rand_bytes = p->num_rand_bytes;
-
-	if (system_is_locked())
-		return EC_RES_ACCESS_DENIED;
-
-	if (num_rand_bytes > args->response_max)
-		return EC_RES_OVERFLOW;
-
-	trng_init();
-	trng_rand_bytes(r->rand, num_rand_bytes);
-	trng_exit();
-
-	args->response_size = num_rand_bytes;
-
-	return EC_SUCCESS;
-}
-
-DECLARE_HOST_COMMAND(EC_CMD_RAND_NUM, host_command_rand,
-		     EC_VER_MASK(EC_VER_RAND_NUM));
-#endif /* SECTION_IS_RW */
-#endif /* CONFIG_CMD_RAND */
diff --git a/common/build.mk b/common/build.mk
index bbc0789f9b..03d1e7bbaf 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -141,8 +141,9 @@ common-$(CONFIG_PWM)+=pwm.o
 common-$(CONFIG_PWM_KBLIGHT)+=pwm_kblight.o
 common-$(CONFIG_KEYBOARD_BACKLIGHT)+=keyboard_backlight.o
 common-$(CONFIG_RGB_KEYBOARD)+=rgb_keyboard.o
-common-$(CONFIG_RSA)+=rsa.o
+common-$(CONFIG_RNG)+=trng.o
 common-$(CONFIG_ROLLBACK)+=rollback.o
+common-$(CONFIG_RSA)+=rsa.o
 common-$(CONFIG_RWSIG)+=rwsig.o vboot/common.o
 common-$(CONFIG_RWSIG_TYPE_RWSIG)+=vboot/vb21_lib.o
 common-$(CONFIG_MATH_UTIL)+=math_util.o
diff --git a/common/trng.c b/common/trng.c
new file mode 100644
index 0000000000..273a078d7a
--- /dev/null
+++ b/common/trng.c
@@ -0,0 +1,82 @@
+/* Copyright 2023 The ChromiumOS Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Common Random Number Generation (RNG) routines */
+
+#include "common.h"
+#include "console.h"
+#include "cpu.h"
+#include "host_command.h"
+#include "panic.h"
+#include "printf.h"
+#include "registers.h"
+#include "system.h"
+#include "task.h"
+#include "trng.h"
+#include "util.h"
+
+test_mockable void trng_rand_bytes(void *buffer, size_t len)
+{
+	while (len) {
+		uint32_t number = trng_rand();
+		size_t cnt = 4;
+		/* deal with the lack of alignment guarantee in the API */
+		uintptr_t align = (uintptr_t)buffer & 3;
+
+		if (len < 4 || align) {
+			cnt = MIN(4 - align, len);
+			memcpy(buffer, &number, cnt);
+		} else {
+			*(uint32_t *)buffer = number;
+		}
+		len -= cnt;
+		buffer += cnt;
+	}
+}
+
+#if defined(CONFIG_CMD_RAND)
+/*
+ * We want to avoid accidentally exposing debug commands in RO since we can't
+ * update RO once in production.
+ */
+#if defined(SECTION_IS_RW)
+static int command_rand(int argc, const char **argv)
+{
+	uint8_t data[32];
+	char str_buf[hex_str_buf_size(sizeof(data))];
+
+	trng_init();
+	trng_rand_bytes(data, sizeof(data));
+	trng_exit();
+	snprintf_hex_buffer(str_buf, sizeof(str_buf),
+			    HEX_BUF(data, sizeof(data)));
+	ccprintf("rand %s\n", str_buf);
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(rand, command_rand, NULL,
+			"Output random bytes to console.");
+
+static enum ec_status host_command_rand(struct host_cmd_handler_args *args)
+{
+	const struct ec_params_rand_num *p = args->params;
+	struct ec_response_rand_num *r = args->response;
+	uint16_t num_rand_bytes = p->num_rand_bytes;
+
+	if (system_is_locked())
+		return EC_RES_ACCESS_DENIED;
+	if (num_rand_bytes > args->response_max)
+		return EC_RES_OVERFLOW;
+	trng_init();
+	trng_rand_bytes(r->rand, num_rand_bytes);
+	trng_exit();
+	args->response_size = num_rand_bytes;
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_HOST_COMMAND(EC_CMD_RAND_NUM, host_command_rand,
+		     EC_VER_MASK(EC_VER_RAND_NUM));
+#endif /* SECTION_IS_RW */
+#endif /* CONFIG_CMD_RAND */
diff --git a/include/trng.h b/include/trng.h
index ca8144eeec..06fbcc8544 100644
--- a/include/trng.h
+++ b/include/trng.h
@@ -26,6 +26,13 @@
 void trng_init(void);
 
 /**
+ * Generate true random number.
+ *
+ * Not supported by all platforms.
+ **/
+uint32_t trng_rand(void);
+
+/**
  * Shutdown the true random number generator.
  *
  * The opposite operation of trng_init(), disable the hardware resources