drivers: hwinfo: sam: Introduce RSTC driver

Add a new hwinfo driver to get the reset cause on
SAM4S/SAME70/SAMV71 SoC series.

The user-nrst dts property has been added to enable external user
resets.

Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>

drivers/hwinfo/CMakeLists.txt

@@ -16,6 +16,7 @@ zephyr_library_sources_ifdef(CONFIG_HWINFO_MCUX_SRC    hwinfo_mcux_src.c)
 zephyr_library_sources_ifdef(CONFIG_HWINFO_MCUX_SYSCON hwinfo_mcux_syscon.c)
 zephyr_library_sources_ifdef(CONFIG_HWINFO_NRF         hwinfo_nrf.c)
 zephyr_library_sources_ifdef(CONFIG_HWINFO_PSOC6       hwinfo_psoc6.c)
+zephyr_library_sources_ifdef(CONFIG_HWINFO_SAM_RSTC    hwinfo_sam_rstc.c)
 zephyr_library_sources_ifdef(CONFIG_HWINFO_SAM         hwinfo_sam.c)
 zephyr_library_sources_ifdef(CONFIG_HWINFO_SAM0        hwinfo_sam0.c)
 zephyr_library_sources_ifdef(CONFIG_HWINFO_SAM4L       hwinfo_sam4l.c)

drivers/hwinfo/Kconfig

@@ -70,12 +70,20 @@ config HWINFO_IMXRT
 	help
 	  Enable NXP i.mx RT hwinfo driver.
 
+config HWINFO_SAM_RSTC
+	bool "Atmel SAM reset cause"
+	default y
+	depends on SOC_SERIES_SAM4S || SOC_SERIES_SAME70 || \
+		   SOC_SERIES_SAMV71
+	help
+	  Enable Atmel SAM reset cause hwinfo driver.
+
 config HWINFO_SAM
 	bool "Atmel SAM device ID"
 	default y
 	depends on SOC_FAMILY_SAM && !SOC_SERIES_SAM4L
 	help
-	  Enable Atmel SAM hwinfo driver.
+	  Enable Atmel SAM device ID hwinfo driver.
 
 config HWINFO_SAM4L
 	bool "Atmel SAM4L device ID"

drivers/hwinfo/hwinfo_sam_rstc.c

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2022 Basalte bv
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT atmel_sam_rstc
+
+#include <device.h>
+#include <drivers/hwinfo.h>
+#include <init.h>
+#include <soc.h>
+
+BUILD_ASSERT(DT_NUM_INST_STATUS_OKAY(DT_DRV_COMPAT) == 1,
+	     "No atmel,sam-rstc compatible device found");
+
+int z_impl_hwinfo_get_reset_cause(uint32_t *cause)
+{
+	/* Get reason from Status Register */
+	uint32_t reason = ((Rstc *)DT_INST_REG_ADDR(0))->RSTC_SR & RSTC_SR_RSTTYP_Msk;
+
+	switch (reason) {
+	case RSTC_SR_RSTTYP_GENERAL_RST:
+		*cause = RESET_POR;
+		break;
+	case RSTC_SR_RSTTYP_BACKUP_RST:
+		*cause = RESET_LOW_POWER_WAKE;
+		break;
+	case RSTC_SR_RSTTYP_WDT_RST:
+		*cause = RESET_WATCHDOG;
+		break;
+	case RSTC_SR_RSTTYP_SOFT_RST:
+		*cause = RESET_SOFTWARE;
+		break;
+	case RSTC_SR_RSTTYP_USER_RST:
+		*cause = RESET_USER;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+int z_impl_hwinfo_get_supported_reset_cause(uint32_t *supported)
+{
+	*supported = RESET_POR
+		   | RESET_LOW_POWER_WAKE
+		   | RESET_WATCHDOG
+		   | RESET_SOFTWARE
+		   | RESET_USER;
+
+	return 0;
+}
+
+static int hwinfo_rstc_init(const struct device *dev)
+{
+	Rstc *regs = (Rstc *)DT_INST_REG_ADDR(0);
+	uint32_t mode;
+
+	ARG_UNUSED(dev);
+
+	/* Enable RSTC in PMC */
+	soc_pmc_peripheral_enable(DT_INST_PROP(0, peripheral_id));
+
+	/* Get current Mode Register value */
+	mode = regs->RSTC_MR;
+
+	/* Enable/disable user reset on NRST */
+#if DT_INST_PROP(0, user_nrst)
+	mode &= ~RSTC_MR_KEY_Msk;
+	mode |= (RSTC_MR_URSTEN | RSTC_MR_KEY_PASSWD);
+#else
+	mode &= ~(RSTC_MR_URSTEN | RSTC_MR_KEY_Msk);
+	mode |= RSTC_MR_KEY_PASSWD;
+#endif
+
+	/* Set Mode Register value */
+	regs->RSTC_MR = mode;
+
+	return 0;
+}
+
+SYS_INIT(hwinfo_rstc_init, POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEVICE);

dts/arm/atmel/sam4s.dtsi

@@ -210,6 +210,13 @@
 			label = "TC1";
 			pinctrl-0 = <>;
 		};
+
+		rstc: rstc@400e1400 {
+			compatible = "atmel,sam-rstc";
+			reg = <0x400e1400 0x10>;
+			peripheral-id = <1>;
+			label = "RSTC";
+		};
 	};
 };
 

dts/arm/atmel/same70.dtsi

@@ -492,6 +492,13 @@
 				label = "CAN_1";
 			};
 		};
+
+		rstc: rstc@400e1800 {
+			compatible = "atmel,sam-rstc";
+			reg = <0x400e1800 0x10>;
+			peripheral-id = <1>;
+			label = "RSTC";
+		};
 	};
 };
 

dts/bindings/hwinfo/atmel,sam-rstc.yaml

@@ -0,0 +1,21 @@
+# Copyright (c) 2022 Basalte bv
+# SPDX-License-Identifier: Apache-2.0
+
+description: ATMEL SAM Reset controller
+
+compatible: "atmel,sam-rstc"
+
+include: base.yaml
+
+properties:
+  reg:
+    required: true
+
+  peripheral-id:
+    type: int
+    description: peripheral ID
+    required: true
+
+  user-nrst:
+    type: boolean
+    description: Allow user reset on external NRST assert.