From c646552238286b8dfd0fe3a3b5235efc26325c10 Mon Sep 17 00:00:00 2001
From: Ghazan Haider <ghazan_haider@manulife.com>
Date: Thu, 7 Sep 2023 22:15:04 -0400
Subject: [PATCH] clock files added

---
 clk.c  |  26 +++++++++++
 clk1.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 171 insertions(+)
 create mode 100644 clk.c
 create mode 100644 clk1.c

diff --git a/clk.c b/clk.c
new file mode 100644
index 0000000..2bb3ff1
--- /dev/null
+++ b/clk.c
@@ -0,0 +1,26 @@
+Starting from DTS point:
+
+CLK_OF_DECLARE(at91rm9200_clk_main_osc, "atmel,at91rm9200-clk-main-osc",
+	       of_at91rm9200_clk_main_osc_setup);
+
+
+of_at91sam9260_clk_slow_setup()
+- at91_clk_register_sam9260_slow(regmap, name, parent_name, bypass);		slowck+clk_hw is born!
+ - clk_hw_register(NULL, slowck->hw);
+  - clk_register(dev, hw)     returns clk*									clk_core is born!
+   - INIT_HLIST_HEAD(&core->clks);											create clk list for core?
+   - __clk_create_clk(hw, NULL, NULL);										clk is born!
+    - hlist_add_head(&clk->clks_node, &hw->core->clks);						clk is added as a node to the hlist core->clks
+   - __clk_core_init(core);
+- of_clk_add_hw_provider(np, of_clk_hw_simple_get, hw);						of_clk_provider is born! But we never see the message!
+
+
+
+
+__clk_create_clk creates clk from clk_hw (in memory)
+
+
+struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id,
+			     const char *con_id)
+
+
diff --git a/clk1.c b/clk1.c
new file mode 100644
index 0000000..4498c8f
--- /dev/null
+++ b/clk1.c
@@ -0,0 +1,145 @@
+Clock hlists:
+
+
+static struct hlist_head *all_lists[] = {
+	&clk_root_list,
+	&clk_orphan_list,
+	NULL,
+};
+
+of_clk_providers ?
+
+
+
+
+
+clk points to clk_core
+
+clk_core point to clk_hw 
+
+clk_hw points to clk_core and clk
+
+
+===============================
+
+struct clk_core {
+	const char		*name;
+	const struct clk_ops	*ops;
+	struct clk_hw		*hw;
+	struct module		*owner;
+	struct device		*dev;
+	struct clk_core		*parent;
+	const char		**parent_names;
+	struct clk_core		**parents;
+	u8			num_parents;
+	u8			new_parent_index;
+	unsigned long		rate;
+	unsigned long		req_rate;
+	unsigned long		new_rate;
+	struct clk_core		*new_parent;
+	struct clk_core		*new_child;
+	unsigned long		flags;
+	bool			orphan;
+	unsigned int		enable_count;
+	unsigned int		prepare_count;
+	unsigned int		protect_count;
+	unsigned long		min_rate;
+	unsigned long		max_rate;
+	unsigned long		accuracy;
+	int			phase;
+	struct clk_duty		duty;
+	struct hlist_head	children;
+	struct hlist_node	child_node;
+	struct hlist_head	clks;
+	unsigned int		notifier_count;
+#ifdef CONFIG_DEBUG_FS
+	struct dentry		*dentry;
+	struct hlist_node	debug_node;
+#endif
+	struct kref		ref;
+};
+
+=============================
+clk includes clk_core
+
+struct clk {
+	struct clk_core	*core;
+	const char *dev_id;
+	const char *con_id;
+	unsigned long min_rate;
+	unsigned long max_rate;
+	unsigned int exclusive_count;
+	struct hlist_node clks_node;
+};
+=============================
+Points to both parents clk and clk_core
+points to clk_init_data which is reset to NULL once clk_register() is called on it.
+
+/**
+ * struct clk_hw - handle for traversing from a struct clk to its corresponding
+ * hardware-specific structure.  struct clk_hw should be declared within struct
+ * clk_foo and then referenced by the struct clk instance that uses struct
+ * clk_foo's clk_ops
+ *
+ * @core: pointer to the struct clk_core instance that points back to this
+ * struct clk_hw instance
+ *
+ * @clk: pointer to the per-user struct clk instance that can be used to call
+ * into the clk API
+ *
+ * @init: pointer to struct clk_init_data that contains the init data shared
+ * with the common clock framework. This pointer will be set to NULL once
+ * a clk_register() variant is called on this clk_hw pointer.
+ */
+
+struct clk_hw {
+	struct clk_core *core;
+	struct clk *clk;
+	const struct clk_init_data *init;
+};
+=============================
+
+/**
+ * struct clk_init_data - holds init data that's common to all clocks and is
+ * shared between the clock provider and the common clock framework.
+ *
+ * @name: clock name
+ * @ops: operations this clock supports
+ * @parent_names: array of string names for all possible parents
+ * @num_parents: number of possible parents
+ * @flags: framework-level hints and quirks
+ */
+struct clk_init_data {
+	const char		*name;
+	const struct clk_ops	*ops;
+	const char		* const *parent_names;
+	u8			num_parents;
+	unsigned long		flags;
+};
+=============================
+struct clk_sam9260_slow {
+	struct clk_hw hw;
+	struct regmap *regmap;
+};
+=============================
+/**
+ * struct of_clk_provider - Clock provider registration structure
+ * @link: Entry in global list of clock providers
+ * @node: Pointer to device tree node of clock provider
+ * @get: Get clock callback.  Returns NULL or a struct clk for the
+ *       given clock specifier
+ * @data: context pointer to be passed into @get callback
+ */
+struct of_clk_provider {
+	struct list_head link;
+
+	struct device_node *node;
+	struct clk *(*get)(struct of_phandle_args *clkspec, void *data);
+	struct clk_hw *(*get_hw)(struct of_phandle_args *clkspec, void *data);
+	void *data;
+};
+
+static LIST_HEAD(of_clk_providers);
+===========================
+
+