drivers: timer: Add RTC timer driver for cc23x0

Add support for RTC as timer for cc23x0 SoC.

Signed-off-by: Stoyan Bogdanov <sbogdanov@baylibre.com>

Author: bogdanovs

drivers/timer/CMakeLists.txt

@@ -12,6 +12,7 @@ zephyr_library_sources_ifdef(CONFIG_ARM_ARCH_TIMER arm_arch_timer.c)
 zephyr_library_sources_ifdef(CONFIG_INTEL_ADSP_TIMER intel_adsp_timer.c)
 zephyr_library_sources_ifdef(CONFIG_CC13XX_CC26XX_RTC_TIMER cc13xx_cc26xx_rtc_timer.c)
 zephyr_library_sources_ifdef(CONFIG_CC23X0_SYSTIM_TIMER cc23x0_systim_timer.c)
+zephyr_library_sources_ifdef(CONFIG_CC23X0_RTC_TIMER cc23x0_rtc_timer.c)
 zephyr_library_sources_ifdef(CONFIG_CH32V00X_SYSTICK wch_systick_ch32v00x.c)
 zephyr_library_sources_ifdef(CONFIG_CORTEX_M_SYSTICK cortex_m_systick.c)
 zephyr_library_sources_ifdef(CONFIG_ESP32_SYS_TIMER esp32_sys_timer.c)

drivers/timer/Kconfig.cc23x0_rtc

@@ -0,0 +1,12 @@
+# Copyright (c) 2024 BayLibre, SAS
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config CC23X0_RTC_TIMER
+	bool "TI SimpleLink CC23X0 RTC system clock timer"
+	default y
+	depends on HAS_CC23X0_SDK
+	select TICKLESS_CAPABLE
+	help
+	  This module provides the RTC as "system clock driver" interfaces
+	  for the TI Simplelink CC23X0 devices.

drivers/timer/cc23x0_rtc_timer.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2024 BayLibre, SAS
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT ti_cc23x0_rtc_timer
+
+#include <soc.h>
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/clock_control.h>
+#include <zephyr/drivers/timer/system_timer.h>
+#include <zephyr/irq.h>
+#include <zephyr/spinlock.h>
+#include <zephyr/sys_clock.h>
+#include <zephyr/sys/util.h>
+
+#include <inc/hw_rtc.h>
+#include <inc/hw_types.h>
+#include <inc/hw_evtsvt.h>
+#include <inc/hw_memmap.h>
+
+#define RTC_TIMEOUT_MAX 0xFFBFFFFFU
+
+/* Set rtc interrupt to lowest priority */
+#define SYSTIM_ISR_PRIORITY 3U
+
+/* Keep track of rtc counter at previous announcement to the kernel */
+static uint32_t last_rtc_count;
+
+static void rtc_isr(const void *arg);
+static int sys_clock_driver_init(void);
+
+void sys_clock_set_timeout(int32_t ticks, bool idle)
+{
+	ARG_UNUSED(idle);
+
+	/* If timeout is necessary */
+	if (ticks != K_TICKS_FOREVER) {
+		/* Get current value as early as possible */
+		uint32_t ticks_now = HWREG(RTC_BASE + RTC_O_TIME8U);
+
+		if ((ticks_now + ticks) >= RTC_TIMEOUT_MAX) {
+			/* Reset timer and start from 0 */
+			HWREG(RTC_BASE + RTC_O_CTL) = 0x1;
+			HWREG(RTC_BASE + RTC_O_CH0CC8U) = ticks;
+		}
+
+		HWREG(RTC_BASE + RTC_O_CH0CC8U) = ticks_now + ticks;
+	}
+}
+
+uint32_t sys_clock_elapsed(void)
+{
+	uint32_t current_rtc_count = HWREG(RTC_BASE + RTC_O_TIME8U);
+
+	uint32_t elapsed_rtc;
+
+	if (current_rtc_count >= last_rtc_count) {
+		elapsed_rtc = current_rtc_count - last_rtc_count;
+	} else {
+		elapsed_rtc = (0xFFFFFFFF - last_rtc_count) + current_rtc_count;
+	}
+
+	int32_t elapsed_ticks = elapsed_rtc;
+
+	return elapsed_ticks;
+}
+
+uint32_t sys_clock_cycle_get_32(void)
+{
+	return HWREG(RTC_BASE + RTC_O_TIME8U);
+}
+
+void rtc_isr(const void *arg)
+{
+	uint32_t current_rtc_count = HWREG(RTC_BASE + RTC_O_TIME8U);
+
+	uint32_t elapsed_rtc;
+
+	if (current_rtc_count >= last_rtc_count) {
+		elapsed_rtc = current_rtc_count - last_rtc_count;
+	} else {
+		elapsed_rtc = (0xFFFFFFFF - last_rtc_count) + current_rtc_count;
+	}
+
+	int32_t elapsed_ticks = elapsed_rtc;
+
+	HWREG(RTC_BASE + RTC_O_ICLR) = 0x1;
+
+	sys_clock_announce(elapsed_ticks);
+
+	last_rtc_count = current_rtc_count;
+}
+
+static int sys_clock_driver_init(void)
+{
+	uint32_t now_ticks;
+
+	now_ticks = HWREG(RTC_BASE + RTC_O_TIME8U);
+	last_rtc_count = now_ticks;
+
+	HWREG(RTC_BASE + RTC_O_ICLR) = 0x3;
+	HWREG(RTC_BASE + RTC_O_IMCLR) = 0x3;
+
+	HWREG(EVTSVT_BASE + EVTSVT_O_CPUIRQ16SEL) = EVTSVT_CPUIRQ16SEL_PUBID_AON_RTC_COMB;
+	HWREG(RTC_BASE + RTC_O_CH0CC8U) = now_ticks + RTC_TIMEOUT_MAX;
+
+	HWREG(RTC_BASE + RTC_O_IMASK) = 0x1;
+	HWREG(RTC_BASE + RTC_O_ARMSET) = 0x1;
+
+	/* Take configurable interrupt IRQ16 for rtc */
+	IRQ_CONNECT(CPUIRQ16_IRQn, SYSTIM_ISR_PRIORITY, rtc_isr, 0, 0);
+	irq_enable(CPUIRQ16_IRQn);
+
+	return 0;
+}
+
+SYS_INIT(sys_clock_driver_init, PRE_KERNEL_2, CONFIG_SYSTEM_CLOCK_INIT_PRIORITY);