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).

4 files changed, 184 insertions, 3 deletions

diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index 805a6fd6797..9006c769279 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 00000000000..23902234cc8
--- /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 <[email protected]>
+ */
+
+#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 9deb2cf61cc..3b2ba091247 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 813cc8f2a5d..0a9777edcba 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.
  */