Merge branch '2022-09-13-add-support-for-cyclic-function-execution' into next

To quote the author:
This patchset adds the basic infrastructure to periodically execute
code, e.g. all 100ms. Examples for such functions might be LED blinking
etc. The functions that are hooked into this cyclic list should be
small timewise as otherwise the execution of the other code that relies
on a high frequent polling (e.g. UART rx char ready check) might be
delayed too much. This patch also adds the Kconfig option
CONFIG_CYCLIC_MAX_CPU_TIME_US, which configures the max allowed time
for such a cyclic function. If it's execution time exceeds this time,
this cyclic function will get removed from the cyclic list.

How is this cyclic functionality executed?
This patchset integrates the main function responsible for calling all
registered cyclic functions cyclic_run() into the common WATCHDOG_RESET
macro. This guarantees that cyclic_run() is executed very often, which
is necessary for the cyclic functions to get scheduled and executed at
their configured periods.

This cyclic infrastructure will be used by a board specific function on
the NIC23 MIPS Octeon board, which needs to check periodically, if a
PCIe FLR has occurred.

Ideas how to continue:
One idea is to rename WATCHDOG_RESET to something like SCHEDULE and
move the watchdog_reset call into this cyclic infrastructure as well.
Or to perhaps move the shell UART RX ready polling to a cyclic
function.

It's also possible to extend the "cyclic" command, to support the
creation of periodically executed shell commands (for testing etc).

23 files changed, 777 insertions, 4 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 1ebcd36..25a11a0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -795,6 +795,13 @@ T:	git https://source.denx.de/u-boot/custodians/u-boot-coldfire.git
 F:	arch/m68k/
 F:	doc/arch/m68k.rst
 
+CYCLIC
+M:	Stefan Roese <sr@denx.de>
+S:	Maintained
+F:	cmd/cyclic.c
+F:	common/cyclic.c
+F:	include/cyclic.h
+
 DFU
 M:	Lukasz Majewski <lukma@denx.de>
 S:	Maintained
diff --git a/board/Marvell/octeon_nic23/board.c b/board/Marvell/octeon_nic23/board.c
index 3e2c544..08b1aa4 100644
--- a/board/Marvell/octeon_nic23/board.c
+++ b/board/Marvell/octeon_nic23/board.c
@@ -3,8 +3,10 @@
  * Copyright (C) 2021-2022 Stefan Roese <sr@denx.de>
  */
 
+#include <cyclic.h>
 #include <dm.h>
 #include <ram.h>
+#include <time.h>
 #include <asm/gpio.h>
 
 #include <mach/octeon_ddr.h>
@@ -15,11 +17,90 @@
 #include <mach/cvmx-helper-cfg.h>
 #include <mach/cvmx-helper-util.h>
 #include <mach/cvmx-bgxx-defs.h>
+#include <mach/cvmx-dtx-defs.h>
 
 #include "board_ddr.h"
 
+/**
+ * cvmx_spem#_cfg_rd
+ *
+ * This register allows read access to the configuration in the PCIe core.
+ *
+ */
+union cvmx_spemx_cfg_rd {
+	u64 u64;
+	struct cvmx_spemx_cfg_rd_s {
+		u64 data                         : 32;
+		u64 addr                         : 32;
+	} s;
+	struct cvmx_spemx_cfg_rd_s            cn73xx;
+};
+
+/**
+ * cvmx_spem#_cfg_wr
+ *
+ * This register allows write access to the configuration in the PCIe core.
+ *
+ */
+union cvmx_spemx_cfg_wr {
+	u64 u64;
+	struct cvmx_spemx_cfg_wr_s {
+		u64 data                         : 32;
+		u64 addr                         : 32;
+	} s;
+	struct cvmx_spemx_cfg_wr_s            cn73xx;
+};
+
+/**
+ * cvmx_spem#_flr_pf_stopreq
+ *
+ * PF function level reset stop outbound requests register.
+ * Hardware automatically sets the STOPREQ bit for the PF when it enters a
+ * function level reset (FLR).  Software is responsible for clearing the STOPREQ
+ * bit but must not do so prior to hardware taking down the FLR, which could be
+ * as long as 100ms.  It may be appropriate for software to wait longer before clearing
+ * STOPREQ, software may need to drain deep DPI queues for example.
+ * Whenever SPEM receives a PF or child VF request mastered by CNXXXX over S2M (i.e. P or NP),
+ * when STOPREQ is set for the function, SPEM will discard the outgoing request
+ * before sending it to the PCIe core.  If a NP, SPEM will schedule an immediate
+ * SWI_RSP_ERROR completion for the request - no timeout is required.
+ * In both cases, SPEM()_DBG_PF()_INFO[P()_BMD_E] will be set and a error
+ * interrupt is generated.
+ *
+ * STOPREQ mimics the behavior of PCIEEP()_CFG001[ME] for outbound requests that will
+ * master the PCIe bus (P and NP).
+ *
+ * STOPREQ will have no effect on completions returned by CNXXXX over the S2M,
+ * nor on M2S traffic.
+ *
+ * When a PF()_STOPREQ is set, none of the associated
+ * PEM()_FLR_PF()_VF_STOPREQ[VF_STOPREQ] will be set.
+ *
+ * STOPREQ is reset when the MAC is reset, and is not reset after a chip soft reset.
+ */
+union cvmx_spemx_flr_pf_stopreq {
+	u64 u64;
+	struct cvmx_spemx_flr_pf_stopreq_s {
+		u64 reserved_3_63                : 61;
+		u64 pf2_stopreq                  : 1;
+		u64 pf1_stopreq                  : 1;
+		u64 pf0_stopreq                  : 1;
+	} s;
+	struct cvmx_spemx_flr_pf_stopreq_s    cn73xx;
+};
+
+#define CVMX_SPEMX_CFG_WR(offset)		0x00011800C0000028ull
+#define CVMX_SPEMX_CFG_RD(offset)		0x00011800C0000030ull
+#define CVMX_SPEMX_FLR_PF_STOPREQ(offset)	0x00011800C0000218ull
+
+#define DTX_SELECT_LTSSM		0x0
+#define DTX_SELECT_LTSSM_ENA		0x3ff
+#define LTSSM_L0			0x11
+
 #define NIC23_DEF_DRAM_FREQ		800
 
+static u32 pci_cfgspace_reg0[2] = { 0, 0 };
+
 static u8 octeon_nic23_cfg0_spd_values[512] = {
 	OCTEON_NIC23_CFG0_SPD_VALUES
 };
@@ -145,8 +226,118 @@ void board_configure_qlms(void)
 	      cvmx_qlm_measure_clock(4), cvmx_qlm_measure_clock(5));
 }
 
+/**
+ * If there is a PF FLR then the PCI EEPROM is not re-read.  In this case
+ * we need to re-program the vendor and device ID immediately after hardware
+ * completes FLR.
+ *
+ * PCI spec requires FLR to be completed within 100ms.  The user who triggered
+ * FLR expects hardware to finish FLR within 100ms, otherwise the user will
+ * end up reading DEVICE_ID incorrectly from the reset value.
+ * CN23XX exits FLR at any point between 66 and 99ms, so U-Boot has to wait
+ * 99ms to let hardware finish its part, then finish reprogramming the
+ * correct device ID before the end of 100ms.
+ *
+ * Note: this solution only works properly when there is no other activity
+ * within U-Boot for 100ms from the time FLR is triggered.
+ *
+ * This function gets called every 100usec.  If FLR happens during any
+ * other activity like bootloader/image update then it is possible that
+ * this function does not get called for more than the FLR period which will
+ * cause the PF device ID restore to happen after whoever initiated the FLR to
+ * read the incorrect device ID 0x9700 (reset value) instead of 0x9702
+ * (restored value).
+ */
+static void octeon_board_restore_pf(void *ctx)
+{
+	union cvmx_spemx_flr_pf_stopreq stopreq;
+	static bool start_initialized[2] = {false, false};
+	bool pf0_flag, pf1_flag;
+	u64 ltssm_bits;
+	const u64 pf_flr_wait_usecs = 99700;
+	u64 elapsed_usecs;
+	union cvmx_spemx_cfg_wr cfg_wr;
+	union cvmx_spemx_cfg_rd cfg_rd;
+	static u64 start_us[2];
+	int pf_num;
+
+	csr_wr(CVMX_DTX_SPEM_SELX(0), DTX_SELECT_LTSSM);
+	csr_rd(CVMX_DTX_SPEM_SELX(0));
+	csr_wr(CVMX_DTX_SPEM_ENAX(0), DTX_SELECT_LTSSM_ENA);
+	csr_rd(CVMX_DTX_SPEM_ENAX(0));
+	ltssm_bits = csr_rd(CVMX_DTX_SPEM_DATX(0));
+	if (((ltssm_bits >> 3) & 0x3f) != LTSSM_L0)
+		return;
+
+	stopreq.u64 = csr_rd(CVMX_SPEMX_FLR_PF_STOPREQ(0));
+	pf0_flag = stopreq.s.pf0_stopreq;
+	pf1_flag = stopreq.s.pf1_stopreq;
+	/* See if PF interrupt happened */
+	if (!(pf0_flag || pf1_flag))
+		return;
+
+	if (pf0_flag && !start_initialized[0]) {
+		start_initialized[0] = true;
+		start_us[0] = get_timer_us(0);
+	}
+
+	/* Store programmed PCIe DevID SPEM0 PF0 */
+	if (pf0_flag && !pci_cfgspace_reg0[0]) {
+		cfg_rd.s.addr = (0 << 24) | 0x0;
+		csr_wr(CVMX_SPEMX_CFG_RD(0), cfg_rd.u64);
+		cfg_rd.u64 = csr_rd(CVMX_SPEMX_CFG_RD(0));
+		pci_cfgspace_reg0[0] = cfg_rd.s.data;
+	}
+
+	if (pf1_flag && !start_initialized[1]) {
+		start_initialized[1] = true;
+		start_us[1] = get_timer_us(0);
+	}
+
+	/* Store programmed PCIe DevID SPEM0 PF1 */
+	if (pf1_flag && !pci_cfgspace_reg0[1]) {
+		cfg_rd.s.addr = (1 << 24) | 0x0;
+		csr_wr(CVMX_SPEMX_CFG_RD(0), cfg_rd.u64);
+		cfg_rd.u64 = csr_rd(CVMX_SPEMX_CFG_RD(0));
+		pci_cfgspace_reg0[1] = cfg_rd.s.data;
+	}
+
+	/* For PF, rewrite pci config space reg 0 */
+	for (pf_num = 0; pf_num < 2; pf_num++) {
+		if (!start_initialized[pf_num])
+			continue;
+
+		elapsed_usecs = get_timer_us(0) - start_us[pf_num];
+
+		if (elapsed_usecs > pf_flr_wait_usecs) {
+			/* Here, our measured FLR duration has passed;
+			 * check if device ID has been reset,
+			 * which indicates FLR completion (per MA team).
+			 */
+			cfg_rd.s.addr = (pf_num << 24) | 0x0;
+			csr_wr(CVMX_SPEMX_CFG_RD(0), cfg_rd.u64);
+			cfg_rd.u64 = csr_rd(CVMX_SPEMX_CFG_RD(0));
+			/* if DevID has NOT been reset, FLR is not yet
+			 * complete
+			 */
+			if (cfg_rd.s.data != pci_cfgspace_reg0[pf_num]) {
+				stopreq.s.pf0_stopreq = (pf_num == 0) ? 1 : 0;
+				stopreq.s.pf1_stopreq = (pf_num == 1) ? 1 : 0;
+				csr_wr(CVMX_SPEMX_FLR_PF_STOPREQ(0), stopreq.u64);
+
+				cfg_wr.u64 = 0;
+				cfg_wr.s.addr = (pf_num << 24) | 0;
+				cfg_wr.s.data = pci_cfgspace_reg0[pf_num];
+				csr_wr(CVMX_SPEMX_CFG_WR(0), cfg_wr.u64);
+				start_initialized[pf_num] = false;
+			}
+		}
+	}
+}
+
 int board_late_init(void)
 {
+	struct cyclic_info *cyclic;
 	struct gpio_desc gpio = {};
 	ofnode node;
 
@@ -164,6 +355,12 @@ int board_late_init(void)
 
 	board_configure_qlms();
 
+	/* Register cyclic function for PCIe FLR fixup */
+	cyclic = cyclic_register(octeon_board_restore_pf, 100,
+				 "pcie_flr_fix", NULL);
+	if (!cyclic)
+		printf("Registering of cyclic function failed\n");
+
 	return 0;
 }
 
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 67c7d25..7d574d4 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -2511,6 +2511,22 @@ config CMD_CBSYSINFO
 	  memory by coreboot before jumping to U-Boot. It can be useful for
 	  debugging the beaaviour of coreboot or U-Boot.
 
+config CMD_CYCLIC
+	bool "cyclic - Show information about cyclic functions"
+	depends on CYCLIC
+	default y
+	help
+	  This enables the 'cyclic' command which provides information about
+	  cyclic execution functions. This infrastructure allows registering
+	  functions to be executed cyclically, e.g. every 100ms. These commands
+	  are supported:
+
+	    cyclic list - list cyclic functions
+	    cyclic cyclic demo <cycletime_ms> <delay_us> - register cyclic
+		demo function
+
+	  See doc/develop/cyclic.rst for more details.
+
 config CMD_DIAG
 	bool "diag - Board diagnostics"
 	help
diff --git a/cmd/Makefile b/cmd/Makefile
index 7abe1d3..b2df59b 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_CMD_DIAG) += diag.o
 endif
 obj-$(CONFIG_CMD_ADTIMG) += adtimg.o
 obj-$(CONFIG_CMD_ABOOTIMG) += abootimg.o
+obj-$(CONFIG_CMD_CYCLIC) += cyclic.o
 obj-$(CONFIG_CMD_EVENT) += event.o
 obj-$(CONFIG_CMD_EXTENSION) += extension_board.o
 obj-$(CONFIG_CMD_ECHO) += echo.o
diff --git a/cmd/cyclic.c b/cmd/cyclic.c
new file mode 100644
index 0000000..c1bc556
--- /dev/null
+++ b/cmd/cyclic.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * A general-purpose cyclic execution infrastructure, to allow "small"
+ * (run-time wise) functions to be executed at a specified frequency.
+ * Things like LED blinking or watchdog triggering are examples for such
+ * tasks.
+ *
+ * Copyright (C) 2022 Stefan Roese <sr@denx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+#include <cyclic.h>
+#include <div64.h>
+#include <malloc.h>
+#include <linux/delay.h>
+
+struct cyclic_demo_info {
+	uint delay_us;
+};
+
+static void cyclic_demo(void *ctx)
+{
+	struct cyclic_demo_info *info = ctx;
+
+	/* Just a small dummy delay here */
+	udelay(info->delay_us);
+}
+
+static int do_cyclic_demo(struct cmd_tbl *cmdtp, int flag, int argc,
+			  char *const argv[])
+{
+	struct cyclic_demo_info *info;
+	struct cyclic_info *cyclic;
+	uint time_ms;
+
+	if (argc < 3)
+		return CMD_RET_USAGE;
+
+	info = malloc(sizeof(struct cyclic_demo_info));
+	if (!info) {
+		printf("out of memory\n");
+                return CMD_RET_FAILURE;
+	}
+
+	time_ms = simple_strtoul(argv[1], NULL, 0);
+	info->delay_us = simple_strtoul(argv[2], NULL, 0);
+
+	/* Register demo cyclic function */
+	cyclic = cyclic_register(cyclic_demo, time_ms * 1000, "cyclic_demo",
+				 info);
+	if (!cyclic)
+		printf("Registering of cyclic_demo failed\n");
+
+	printf("Registered function \"%s\" to be executed all %dms\n",
+	       "cyclic_demo", time_ms);
+
+	return 0;
+}
+
+static int do_cyclic_list(struct cmd_tbl *cmdtp, int flag, int argc,
+			  char *const argv[])
+{
+	struct cyclic_info *cyclic, *tmp;
+	u64 cnt, freq;
+
+	list_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list) {
+		cnt = cyclic->run_cnt * 1000000ULL * 100ULL;
+		freq = lldiv(cnt, timer_get_us() - cyclic->start_time_us);
+		printf("function: %s, cpu-time: %lld us, frequency: %lld.%02d times/s\n",
+		       cyclic->name, cyclic->cpu_time_us,
+		       lldiv(freq, 100), do_div(freq, 100));
+	}
+
+	return 0;
+}
+
+static char cyclic_help_text[] =
+	"cyclic demo <cycletime_ms> <delay_us> - register cyclic demo function\n"
+	"cyclic list - list cyclic functions\n";
+
+U_BOOT_CMD_WITH_SUBCMDS(cyclic, "Cyclic", cyclic_help_text,
+	U_BOOT_SUBCMD_MKENT(demo, 3, 1, do_cyclic_demo),
+	U_BOOT_SUBCMD_MKENT(list, 1, 1, do_cyclic_list));
diff --git a/common/Kconfig b/common/Kconfig
index 2c3f7f4..3e44acd 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -545,6 +545,26 @@ config DISPLAY_BOARDINFO_LATE
 
 menu "Start-up hooks"
 
+config CYCLIC
+	bool "General-purpose cyclic execution mechanism"
+	help
+	  This enables a general-purpose cyclic execution infrastructure,
+	  to allow "small" (run-time wise) functions to be executed at
+	  a specified frequency. Things like LED blinking or watchdog
+	  triggering are examples for such tasks.
+
+if CYCLIC
+
+config CYCLIC_MAX_CPU_TIME_US
+	int "Sets the max allowed time for a cyclic function in us"
+	default 1000
+	help
+	  The max allowed time for a cyclic function in us. If a functions
+	  takes longer than this duration this function will get unregistered
+	  automatically.
+
+endif # CYCLIC
+
 config EVENT
 	bool "General-purpose event-handling mechanism"
 	default y if SANDBOX
diff --git a/common/Makefile b/common/Makefile
index 2ed8672..1d56c9f 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -84,6 +84,7 @@ obj-y += malloc_simple.o
 endif
 endif
 
+obj-$(CONFIG_CYCLIC) += cyclic.o
 obj-$(CONFIG_$(SPL_TPL_)EVENT) += event.o
 
 obj-$(CONFIG_$(SPL_TPL_)HASH) += hash.o
diff --git a/common/board_f.c b/common/board_f.c
index 18e2246..deb46be 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -16,6 +16,7 @@
 #include <console.h>
 #include <cpu.h>
 #include <cpu_func.h>
+#include <cyclic.h>
 #include <display_options.h>
 #include <dm.h>
 #include <env.h>
@@ -828,6 +829,7 @@ static const init_fnc_t init_sequence_f[] = {
 	initf_malloc,
 	log_init,
 	initf_bootstage,	/* uses its own timer, so does not need DM */
+	cyclic_init,
 	event_init,
 #ifdef CONFIG_BLOBLIST
 	bloblist_init,
diff --git a/common/board_r.c b/common/board_r.c
index 56eb60f..062bc3e 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -13,6 +13,7 @@
 #include <api.h>
 #include <bootstage.h>
 #include <cpu_func.h>
+#include <cyclic.h>
 #include <display_options.h>
 #include <exports.h>
 #ifdef CONFIG_MTD_NOR_FLASH
@@ -611,6 +612,7 @@ static init_fnc_t init_sequence_r[] = {
 #endif
 	initr_barrier,
 	initr_malloc,
+	cyclic_init,
 	log_init,
 	initr_bootstage,	/* Needs malloc() but has its own timer */
 #if defined(CONFIG_CONSOLE_RECORD)
diff --git a/common/cyclic.c b/common/cyclic.c
new file mode 100644
index 0000000..cd5dcb1
--- /dev/null
+++ b/common/cyclic.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * A general-purpose cyclic execution infrastructure, to allow "small"
+ * (run-time wise) functions to be executed at a specified frequency.
+ * Things like LED blinking or watchdog triggering are examples for such
+ * tasks.
+ *
+ * Copyright (C) 2022 Stefan Roese <sr@denx.de>
+ */
+
+#include <cyclic.h>
+#include <log.h>
+#include <malloc.h>
+#include <time.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <asm/global_data.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct list_head *cyclic_get_list(void)
+{
+	return &gd->cyclic->cyclic_list;
+}
+
+struct cyclic_info *cyclic_register(cyclic_func_t func, uint64_t delay_us,
+				    const char *name, void *ctx)
+{
+	struct cyclic_info *cyclic;
+
+	if (!gd->cyclic->cyclic_ready) {
+		pr_debug("Cyclic IF not ready yet\n");
+		return NULL;
+	}
+
+	cyclic = calloc(1, sizeof(struct cyclic_info));
+	if (!cyclic) {
+		pr_debug("Memory allocation error\n");
+		return NULL;
+	}
+
+	/* Store values in struct */
+	cyclic->func = func;
+	cyclic->ctx = ctx;
+	cyclic->name = strdup(name);
+	cyclic->delay_us = delay_us;
+	cyclic->start_time_us = timer_get_us();
+	list_add_tail(&cyclic->list, &gd->cyclic->cyclic_list);
+
+	return cyclic;
+}
+
+int cyclic_unregister(struct cyclic_info *cyclic)
+{
+	list_del(&cyclic->list);
+	free(cyclic);
+
+	return 0;
+}
+
+void cyclic_run(void)
+{
+	struct cyclic_info *cyclic, *tmp;
+	uint64_t now, cpu_time;
+
+	/* Prevent recursion */
+	if (gd->cyclic->cyclic_running)
+		return;
+
+	gd->cyclic->cyclic_running = true;
+	list_for_each_entry_safe(cyclic, tmp, &gd->cyclic->cyclic_list, list) {
+		/*
+		 * Check if this cyclic function needs to get called, e.g.
+		 * do not call the cyclic func too often
+		 */
+		now = timer_get_us();
+		if (time_after_eq64(now, cyclic->next_call)) {
+			/* Call cyclic function and account it's cpu-time */
+			cyclic->next_call = now + cyclic->delay_us;
+			cyclic->func(cyclic->ctx);
+			cyclic->run_cnt++;
+			cpu_time = timer_get_us() - now;
+			cyclic->cpu_time_us += cpu_time;
+
+			/* Check if cpu-time exceeds max allowed time */
+			if (cpu_time > CONFIG_CYCLIC_MAX_CPU_TIME_US) {
+				pr_err("cyclic function %s took too long: %lldus vs %dus max, disabling\n",
+				       cyclic->name, cpu_time,
+				       CONFIG_CYCLIC_MAX_CPU_TIME_US);
+
+				/* Unregister this cyclic function */
+				cyclic_unregister(cyclic);
+			}
+		}
+	}
+	gd->cyclic->cyclic_running = false;
+}
+
+int cyclic_uninit(void)
+{
+	struct cyclic_info *cyclic, *tmp;
+
+	list_for_each_entry_safe(cyclic, tmp, &gd->cyclic->cyclic_list, list)
+		cyclic_unregister(cyclic);
+	gd->cyclic->cyclic_ready = false;
+
+	return 0;
+}
+
+int cyclic_init(void)
+{
+	int size = sizeof(struct cyclic_drv);
+
+	gd->cyclic = (struct cyclic_drv *)malloc(size);
+	if (!gd->cyclic)
+		return -ENOMEM;
+
+	memset(gd->cyclic, '\0', size);
+	INIT_LIST_HEAD(&gd->cyclic->cyclic_list);
+	gd->cyclic->cyclic_ready = true;
+
+	return 0;
+}
diff --git a/configs/octeon_nic23_defconfig b/configs/octeon_nic23_defconfig
index 95e98c1..098831e 100644
--- a/configs/octeon_nic23_defconfig
+++ b/configs/octeon_nic23_defconfig
@@ -20,6 +20,8 @@ CONFIG_AHCI=y
 CONFIG_OF_BOARD_FIXUP=y
 CONFIG_SYS_CONSOLE_ENV_OVERWRITE=y
 # CONFIG_SYS_DEVICE_NULLDEV is not set
+CONFIG_CYCLIC=y
+CONFIG_CYCLIC_MAX_CPU_TIME_US=5000
 CONFIG_ARCH_MISC_INIT=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_BOARD_LATE_INIT=y
@@ -41,6 +43,7 @@ CONFIG_CMD_TIME=y
 CONFIG_CMD_EXT4=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
+CONFIG_CMD_CYCLIC=y
 CONFIG_EFI_PARTITION=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_TFTP_TSIZE=y
diff --git a/doc/develop/cyclic.rst b/doc/develop/cyclic.rst
new file mode 100644
index 0000000..43bedac
--- /dev/null
+++ b/doc/develop/cyclic.rst
@@ -0,0 +1,50 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Cyclic functions
+================
+
+The cyclic function execution infrastruture provides a way to periodically
+execute code, e.g. every 100ms. Examples for such functions might be LED
+blinking etc. The functions that are hooked into this cyclic list should
+be small timewise as otherwise the execution of the other code that relies
+on a high frequent polling (e.g. UART rx char ready check) might be
+delayed too much. To detect cyclic functions with a too long execution
+time, the Kconfig option `CONFIG_CYCLIC_MAX_CPU_TIME_US` is introduced,
+which configures the max allowed time for such a cyclic function. If it's
+execution time exceeds this time, this cyclic function will get removed
+from the cyclic list.
+
+Registering a cyclic function
+-----------------------------
+
+To register a cyclic function, use something like this::
+
+    static void cyclic_demo(void *ctx)
+    {
+        /* Just a small dummy delay here */
+        udelay(10);
+    }
+    
+    int board_init(void)
+    {
+        struct cyclic_info *cyclic;
+        
+        /* Register demo cyclic function */
+        cyclic = cyclic_register(cyclic_demo, 10 * 1000, "cyclic_demo", NULL);
+        if (!cyclic)
+        printf("Registering of cyclic_demo failed\n");
+        
+        return 0;
+    }
+
+This will register the function `cyclic_demo()` to be periodically
+executed all 10ms.
+
+How is this cyclic functionality integrated /  executed?
+--------------------------------------------------------
+
+The cyclic infrastructure integrates the main function responsible for
+calling all registered cyclic functions cyclic_run() into the common
+WATCHDOG_RESET macro. This guarantees that cyclic_run() is executed
+very often, which is necessary for the cyclic functions to get scheduled
+and executed at their configured periods.
diff --git a/doc/develop/index.rst b/doc/develop/index.rst
index f7ee09d..ce6b38e 100644
--- a/doc/develop/index.rst
+++ b/doc/develop/index.rst
@@ -27,6 +27,7 @@ Implementation
    ci_testing
    commands
    config_binding
+   cyclic
    devicetree/index
    distro
    driver-model/index
diff --git a/doc/usage/cmd/cyclic.rst b/doc/usage/cmd/cyclic.rst
new file mode 100644
index 0000000..3085cc7
--- /dev/null
+++ b/doc/usage/cmd/cyclic.rst
@@ -0,0 +1,45 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+cyclic command
+==============
+
+Synopsis
+--------
+
+::
+
+    cyclic list
+
+Description
+-----------
+
+The cyclic list command provides a list of the currently registered
+cyclic functions.
+
+This shows the following information:
+
+Function
+    Function name
+
+cpu-time
+    Total time spent in this cyclic function.
+
+Frequency
+    Frequency of execution of this function, e.g. 100 times/s for a
+    pediod of 10ms.
+
+
+See :doc:`../../develop/cyclic` for more information on cyclic functions.
+
+Example
+-------
+
+::
+
+    => cyclic list
+    function: cyclic_demo, cpu-time: 52906 us, frequency: 99.20 times/s
+
+Configuration
+-------------
+
+The cyclic command is only available if CONFIG_CMD_CYCLIC=y.
diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index 5170fa8..10313f8 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -33,6 +33,7 @@ Shell commands
    cmd/bootz
    cmd/cbsysinfo
    cmd/conitrace
+   cmd/cyclic
    cmd/dm
    cmd/echo
    cmd/env
diff --git a/fs/cramfs/uncompress.c b/fs/cramfs/uncompress.c
index f431cc4..38e10e2 100644
--- a/fs/cramfs/uncompress.c
+++ b/fs/cramfs/uncompress.c
@@ -62,7 +62,7 @@ int cramfs_uncompress_init (void)
 	stream.avail_in = 0;
 
 #if defined(CONFIG_HW_WATCHDOG) || defined(CONFIG_WATCHDOG)
-	stream.outcb = (cb_func) WATCHDOG_RESET;
+	stream.outcb = (cb_func)watchdog_reset_func;
 #else
 	stream.outcb = Z_NULL;
 #endif /* CONFIG_HW_WATCHDOG */
diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index 805a6fd..9006c76 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -20,6 +20,7 @@
  */
 
 #ifndef __ASSEMBLY__
+#include <cyclic.h>
 #include <event_internal.h>
 #include <fdtdec.h>
 #include <membuff.h>
@@ -474,6 +475,12 @@ struct global_data {
 	 */
 	struct event_state event_state;
 #endif
+#ifdef CONFIG_CYCLIC
+	/**
+	 * @cyclic: cyclic driver data
+	 */
+	struct cyclic_drv *cyclic;
+#endif
 	/**
 	 * @dmtag_list: List of DM tags
 	 */
diff --git a/include/cyclic.h b/include/cyclic.h
new file mode 100644
index 0000000..2390223
--- /dev/null
+++ b/include/cyclic.h
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * A general-purpose cyclic execution infrastructure, to allow "small"
+ * (run-time wise) functions to be executed at a specified frequency.
+ * Things like LED blinking or watchdog triggering are examples for such
+ * tasks.
+ *
+ * Copyright (C) 2022 Stefan Roese <sr@denx.de>
+ */
+
+#ifndef __cyclic_h
+#define __cyclic_h
+
+#include <linux/list.h>
+#include <asm/types.h>
+
+/**
+ * struct cyclic_drv - Cyclic driver internal data
+ *
+ * @cyclic_list: Cylic list node
+ * @cyclic_ready: Flag if cyclic infrastructure is ready
+ * @cyclic_running: Flag if cyclic infrastructure is running
+ */
+struct cyclic_drv {
+	struct list_head cyclic_list;
+	bool cyclic_ready;
+	bool cyclic_running;
+};
+
+/**
+ * struct cyclic_info - Information about cyclic execution function
+ *
+ * @func: Function to call periodically
+ * @ctx: Context pointer to get passed to this function
+ * @name: Name of the cyclic function, e.g. shown in the commands
+ * @delay_ns: Delay is ns after which this function shall get executed
+ * @start_time_us: Start time in us, when this function started its execution
+ * @cpu_time_us: Total CPU time of this function
+ * @run_cnt: Counter of executions occurances
+ * @next_call: Next time in us, when the function shall be executed again
+ * @list: List node
+ */
+struct cyclic_info {
+	void (*func)(void *ctx);
+	void *ctx;
+	char *name;
+	uint64_t delay_us;
+	uint64_t start_time_us;
+	uint64_t cpu_time_us;
+	uint64_t run_cnt;
+	uint64_t next_call;
+	struct list_head list;
+};
+
+/** Function type for cyclic functions */
+typedef void (*cyclic_func_t)(void *ctx);
+
+#if defined(CONFIG_CYCLIC)
+/**
+ * cyclic_register - Register a new cyclic function
+ *
+ * @func: Function to call periodically
+ * @delay_us: Delay is us after which this function shall get executed
+ * @name: Cyclic function name/id
+ * @ctx: Context to pass to the function
+ * @return: pointer to cyclic_struct if OK, NULL on error
+ */
+struct cyclic_info *cyclic_register(cyclic_func_t func, uint64_t delay_us,
+				    const char *name, void *ctx);
+
+/**
+ * cyclic_unregister - Unregister a cyclic function
+ *
+ * @cyclic: Pointer to cyclic_struct of the function that shall be removed
+ * @return: 0 if OK, -ve on error
+ */
+int cyclic_unregister(struct cyclic_info *cyclic);
+
+/**
+ * cyclic_init() - Set up cyclic functions
+ *
+ * Init a list of cyclic functions, so that these can be added as needed
+ */
+int cyclic_init(void);
+
+/**
+ * cyclic_uninit() - Clean up cyclic functions
+ *
+ * This removes all cyclic functions
+ */
+int cyclic_uninit(void);
+
+/**
+ * cyclic_get_list() - Get cyclic list pointer
+ *
+ * Return the cyclic list pointer
+ *
+ * @return: pointer to cyclic_list
+ */
+struct list_head *cyclic_get_list(void);
+
+/**
+ * cyclic_run() - Interate over all registered cyclic functions
+ *
+ * Interate over all registered cyclic functions and if the it's function
+ * needs to be executed, then call into these registered functions.
+ */
+void cyclic_run(void);
+#else
+static inline struct cyclic_info *cyclic_register(cyclic_func_t func,
+						  uint64_t delay_us,
+						  const char *name,
+						  void *ctx)
+{
+	return NULL;
+}
+
+static inline int cyclic_unregister(struct cyclic_info *cyclic)
+{
+	return 0;
+}
+
+static inline void cyclic_run(void)
+{
+}
+
+static inline int cyclic_init(void)
+{
+	return 0;
+}
+
+static inline int cyclic_uninit(void)
+{
+	return 0;
+}
+#endif
+
+#endif
diff --git a/include/time.h b/include/time.h
index 9deb2cf..3b2ba09 100644
--- a/include/time.h
+++ b/include/time.h
@@ -83,6 +83,25 @@ uint64_t usec_to_tick(unsigned long usec);
 	(time_after_eq(a,b) && \
 	 time_before(a,c))
 
+/* Same as above, but does so with platform independent 64bit types.
+ * These must be used when utilizing jiffies_64 (i.e. return value of
+ * get_jiffies_64() */
+#define time_after64(a,b)	\
+	(typecheck(__u64, a) &&	\
+	 typecheck(__u64, b) && \
+	 ((__s64)((b) - (a)) < 0))
+#define time_before64(a,b)	time_after64(b,a)
+
+#define time_after_eq64(a,b)	\
+	(typecheck(__u64, a) && \
+	 typecheck(__u64, b) && \
+	 ((__s64)((a) - (b)) >= 0))
+#define time_before_eq64(a,b)	time_after_eq64(b,a)
+
+#define time_in_range64(a, b, c) \
+	(time_after_eq64(a, b) && \
+	 time_before_eq64(a, c))
+
 /**
  * usec2ticks() - Convert microseconds to internal ticks
  *
diff --git a/include/watchdog.h b/include/watchdog.h
index 813cc8f..0a9777e 100644
--- a/include/watchdog.h
+++ b/include/watchdog.h
@@ -11,6 +11,8 @@
 #define _WATCHDOG_H_
 
 #if !defined(__ASSEMBLY__)
+#include <cyclic.h>
+
 /*
  * Reset the watchdog timer, always returns 0
  *
@@ -60,11 +62,16 @@ int init_func_watchdog_reset(void);
 			/* Don't require the watchdog to be enabled in SPL */
 			#if defined(CONFIG_SPL_BUILD) &&		\
 				!defined(CONFIG_SPL_WATCHDOG)
-				#define WATCHDOG_RESET() {}
+				#define WATCHDOG_RESET() { \
+					cyclic_run(); \
+				}
 			#else
 				extern void watchdog_reset(void);
 
-				#define WATCHDOG_RESET watchdog_reset
+				#define WATCHDOG_RESET() { \
+					watchdog_reset(); \
+					cyclic_run(); \
+				}
 			#endif
 		#endif
 	#else
@@ -74,11 +81,21 @@ int init_func_watchdog_reset(void);
 		#if defined(__ASSEMBLY__)
 			#define WATCHDOG_RESET /*XXX DO_NOT_DEL_THIS_COMMENT*/
 		#else
-			#define WATCHDOG_RESET() {}
+			#define WATCHDOG_RESET() { \
+				cyclic_run(); \
+			}
 		#endif /* __ASSEMBLY__ */
 	#endif /* CONFIG_WATCHDOG && !__ASSEMBLY__ */
 #endif /* CONFIG_HW_WATCHDOG */
 
+#if !defined(__ASSEMBLY__)
+/* Currently only needed for fs/cramfs/uncompress.c */
+static inline void watchdog_reset_func(void)
+{
+	WATCHDOG_RESET();
+}
+#endif
+
 /*
  * Prototypes from $(CPU)/cpu.c.
  */
diff --git a/test/common/Makefile b/test/common/Makefile
index 9087788..cc918f6 100644
--- a/test/common/Makefile
+++ b/test/common/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0+
 obj-y += cmd_ut_common.o
 obj-$(CONFIG_AUTOBOOT) += test_autoboot.o
+obj-$(CONFIG_CYCLIC) += cyclic.o
 obj-$(CONFIG_EVENT) += event.o
diff --git a/test/common/cyclic.c b/test/common/cyclic.c
new file mode 100644
index 0000000..a5c4e78
--- /dev/null
+++ b/test/common/cyclic.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022 Stefan Roese <sr@denx.de>
+ */
+
+#include <common.h>
+#include <cyclic.h>
+#include <dm.h>
+#include <test/common.h>
+#include <test/test.h>
+#include <test/ut.h>
+#include <watchdog.h>
+#include <linux/delay.h>
+
+/* Test that cyclic function is called */
+static bool cyclic_active = false;
+
+static void cyclic_test(void *ctx)
+{
+	cyclic_active = true;
+}
+
+static int dm_test_cyclic_running(struct unit_test_state *uts)
+{
+	cyclic_active = false;
+	ut_assertnonnull(cyclic_register(cyclic_test, 10 * 1000, "cyclic_demo",
+					 NULL));
+
+	/* Execute all registered cyclic functions */
+	WATCHDOG_RESET();
+	ut_asserteq(true, cyclic_active);
+
+	return 0;
+}
+COMMON_TEST(dm_test_cyclic_running, 0);
diff --git a/test/test-main.c b/test/test-main.c
index 4f1c54b..ae34002 100644
--- a/test/test-main.c
+++ b/test/test-main.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <console.h>
+#include <cyclic.h>
 #include <dm.h>
 #include <event.h>
 #include <dm/root.h>
@@ -220,6 +221,7 @@ static int dm_test_restore(struct device_node *of_root)
 static int test_pre_run(struct unit_test_state *uts, struct unit_test *test)
 {
 	ut_assertok(event_init());
+	ut_assertok(cyclic_init());
 
 	if (test->flags & UT_TESTF_DM)
 		ut_assertok(dm_test_pre_run(uts));
@@ -265,6 +267,7 @@ static int test_post_run(struct unit_test_state *uts, struct unit_test *test)
 	ut_unsilence_console(uts);
 	if (test->flags & UT_TESTF_DM)
 		ut_assertok(dm_test_post_run(uts));
+	ut_assertok(cyclic_uninit());
 	ut_assertok(event_uninit());
 
 	return 0;