drivers: entropy: Add Gecko trng driver for EFR32BG22

This commit enables entropy driver on EFR32BG22 SoC.

Signed-off-by: Mateusz Sierszulski <msierszulski@antmicro.com>

boards/arm/efr32bg_sltb010a/efr32bg_sltb010a.dts

@@ -115,3 +115,7 @@
 &stimer0 {
 	status = "okay";
 };
+
+&trng {
+	status = "okay";
+};

drivers/entropy/Kconfig.gecko

@@ -9,6 +9,7 @@ config ENTROPY_GECKO_TRNG
 	default y
 	depends on DT_HAS_SILABS_GECKO_TRNG_ENABLED
 	select ENTROPY_HAS_DRIVER
+	select CRYPTO_ACC_GECKO_TRNG if SOC_SERIES_EFR32BG22
 	help
 	  This option enables the true random number generator
 	  driver based on the TRNG.

drivers/entropy/entropy_gecko_trng.c

@@ -13,6 +13,7 @@
 
 static void entropy_gecko_trng_read(uint8_t *output, size_t len)
 {
+#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
 	uint32_t tmp;
 	uint32_t *data = (uint32_t *) output;
 
@@ -28,6 +29,9 @@ static void entropy_gecko_trng_read(uint8_t *output, size_t len)
 		tmp = TRNG0->FIFO;
 		memcpy(data, (const uint8_t *) &tmp, len);
 	}
+#else
+	memcpy(output, ((const uint8_t *) CRYPTOACC_RNGOUT_FIFO_S_MEM_BASE), len);
+#endif
 }
 
 static int entropy_gecko_trng_get_entropy(const struct device *dev,
@@ -40,7 +44,11 @@ static int entropy_gecko_trng_get_entropy(const struct device *dev,
 	ARG_UNUSED(dev);
 
 	while (length) {
+#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
 		available = TRNG0->FIFOLEVEL * 4;
+#else
+		available = CRYPTOACC_RNGCTRL->FIFOLEVEL * 4;
+#endif
 		if (available == 0) {
 			return -EINVAL;
 		}
@@ -63,7 +71,11 @@ static int entropy_gecko_trng_get_entropy_isr(const struct device *dev,
 
 		/* No busy wait; return whatever data is available. */
 		size_t count;
+#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
 		size_t available = TRNG0->FIFOLEVEL * 4;
+#else
+		size_t available = CRYPTOACC_RNGCTRL->FIFOLEVEL * 4;
+#endif
 
 		if (available == 0) {
 			return -ENODATA;
@@ -87,10 +99,19 @@ static int entropy_gecko_trng_get_entropy_isr(const struct device *dev,
 static int entropy_gecko_trng_init(const struct device *dev)
 {
 	/* Enable the TRNG0 clock. */
+#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
 	CMU_ClockEnable(cmuClock_TRNG0, true);
 
 	/* Enable TRNG0. */
 	TRNG0->CONTROL = TRNG_CONTROL_ENABLE;
+#else
+	/* Enable the CRYPTO ACC clock. */
+	CMU_ClockEnable(cmuClock_CRYPTOACC, true);
+
+	/* Enable TRNG */
+	CRYPTOACC_RNGCTRL->RNGCTRL |= CRYPTOACC_RNGCTRL_ENABLE;
+#endif
+
 	return 0;
 }
 

dts/arm/silabs/efr32bg22.dtsi

@@ -13,6 +13,7 @@
 / {
 	chosen {
 		zephyr,flash-controller = &msc;
+		zephyr,entropy = &trng;
 	};
 
 	power-states {
@@ -69,6 +70,13 @@
 			status = "disabled";
 		};
 
+		trng: trng@4c021000 {
+			compatible = "silabs,gecko-trng";
+			reg = <0x4C021000 0x1000>;
+			status = "disabled";
+			interrupts = <0x1 0x0>;
+		};
+
 		i2c0: i2c@5a010000 {
 			compatible = "silabs,gecko-i2c";
 			clock-frequency = <I2C_BITRATE_STANDARD>;

soc/arm/silabs_exx32/Kconfig

@@ -134,6 +134,12 @@ choice SOC_GECKO_EMU_DCDC_MODE
 		bool "Bypass"
 endchoice
 
+config CRYPTO_ACC_GECKO_TRNG
+	bool
+	help
+	  Enable Entropy driver based on the CRYPTO_ACC module for Silicon Labs
+	  Gecko chips.
+
 config SOC_GECKO_DEV_INIT
 	bool
 	help