[alsa-devel] [RFC 02/17] clk: Add clock controller to fine-grain the prepare lock
Krzysztof Kozlowski
k.kozlowski at samsung.com
Tue Aug 16 15:34:59 CEST 2016
Add a new entity - clock controller - so the global clock prepare lock
could be fine-grained per controller. The controller is an abstract way
of representing a hardware block. It overlaps a little with clock
provider so there is a potential of merging them.
The clock hierarchy might span between many controllers so add necessary
locking primitives for locking children, parents or everything.
Add a global controller for drivers not converted to new API. This will
be removed once everything uses per-device/per-driver clock controller.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski at samsung.com>
---
drivers/clk/clk.c | 300 +++++++++++++++++++++++++++++++++++++++++--
include/linux/clk-provider.h | 25 +++-
include/linux/clk.h | 1 +
3 files changed, 310 insertions(+), 16 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 238b989bf778..ee1cedfbaa29 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -35,6 +35,7 @@ static struct task_struct *enable_owner;
static int prepare_refcnt;
static int enable_refcnt;
+static LIST_HEAD(clk_ctrl_list);
static HLIST_HEAD(clk_root_list);
static HLIST_HEAD(clk_orphan_list);
static LIST_HEAD(clk_notifier_list);
@@ -46,6 +47,7 @@ struct clk_core {
const struct clk_ops *ops;
struct clk_hw *hw;
struct module *owner;
+ struct clk_ctrl *ctrl;
struct clk_core *parent;
const char **parent_names;
struct clk_core **parents;
@@ -87,6 +89,24 @@ struct clk {
struct hlist_node clks_node;
};
+struct clk_ctrl {
+ struct device *dev; /* Needed? */
+ struct mutex prepare_lock;
+ struct task_struct *prepare_owner;
+ int prepare_refcnt;
+ struct list_head node;
+};
+
+/*
+ * As a temporary solution, register all clocks which pass NULL as clock
+ * controller under this one. This should be removed after converting
+ * all users to new clock controller aware API.
+ */
+static struct clk_ctrl global_ctrl = {
+ .prepare_lock = __MUTEX_INITIALIZER(global_ctrl.prepare_lock),
+ .node = LIST_HEAD_INIT(global_ctrl.node),
+};
+
/*** locking ***/
static void clk_prepare_lock(void)
{
@@ -148,6 +168,228 @@ static void clk_enable_unlock(unsigned long flags)
spin_unlock_irqrestore(&enable_lock, flags);
}
+static void clk_ctrl_prepare_lock(struct clk_ctrl *ctrl)
+{
+ if (!ctrl)
+ return;
+
+ if (!mutex_trylock(&ctrl->prepare_lock)) {
+ if (ctrl->prepare_owner == current) {
+ ctrl->prepare_refcnt++;
+ return;
+ }
+ mutex_lock(&ctrl->prepare_lock);
+ }
+ WARN_ON_ONCE(ctrl->prepare_owner != NULL);
+ WARN_ON_ONCE(ctrl->prepare_refcnt != 0);
+ ctrl->prepare_owner = current;
+ ctrl->prepare_refcnt = 1;
+}
+
+static void clk_ctrl_prepare_unlock(struct clk_ctrl *ctrl)
+{
+ if (!ctrl)
+ return;
+
+ WARN_ON_ONCE(ctrl->prepare_owner != current);
+ WARN_ON_ONCE(ctrl->prepare_refcnt == 0);
+
+ if (--ctrl->prepare_refcnt)
+ return;
+ ctrl->prepare_owner = NULL;
+ mutex_unlock(&ctrl->prepare_lock);
+}
+
+static void clk_prepare_lock_ctrl(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_ctrl_prepare_lock(core->ctrl);
+}
+
+static void clk_prepare_unlock_ctrl(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_ctrl_prepare_unlock(core->ctrl);
+}
+
+static void clk_prepare_lock_parents_locked(struct clk_core *core)
+{
+ struct clk_ctrl *prev = NULL;
+
+ // lockdep_assert_held(&prepare_lock); // tmp comment?
+
+ if (!core)
+ return;
+
+ do {
+ if (core->ctrl != prev) {
+ clk_ctrl_prepare_lock(core->ctrl);
+ prev = core->ctrl;
+ }
+ } while ((core = core->parent));
+}
+
+static void clk_prepare_lock_parents(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_prepare_lock();
+ clk_prepare_lock_parents_locked(core);
+ clk_prepare_unlock();
+}
+
+static void clk_prepare_unlock_parents_recur(struct clk_core *core,
+ struct clk_ctrl *prev)
+{
+ if (!core)
+ return;
+
+ clk_prepare_unlock_parents_recur(core->parent, core->ctrl);
+ if (core->ctrl != prev)
+ clk_ctrl_prepare_unlock(core->ctrl);
+}
+
+static void clk_prepare_unlock_parents(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_prepare_unlock_parents_recur(core, NULL);
+}
+
+// FIXME: important note - will skip first lock
+static void clk_prepare_lock_children_locked(struct clk_core *core)
+{
+ struct clk_core *child;
+
+ lockdep_assert_held(&prepare_lock);
+
+ if (!core)
+ return;
+
+ hlist_for_each_entry(child, &core->children, child_node) {
+ clk_prepare_lock_children_locked(child);
+
+ /* No need to double lock the same controller */
+ if (child->ctrl != core->ctrl)
+ clk_ctrl_prepare_lock(child->ctrl);
+ }
+}
+
+static void clk_prepare_lock_children(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_prepare_lock();
+ clk_prepare_lock_children_locked(core);
+ /* Initial lock because children recurrency skiped first one */
+ clk_ctrl_prepare_lock(core->ctrl);
+}
+
+static void clk_prepare_unlock_children_locked(struct clk_core *core)
+{
+ struct clk_core *child;
+
+ if (!core)
+ return;
+
+ hlist_for_each_entry(child, &core->children, child_node) {
+ /* No need to double unlock the same controller */
+ if (child->ctrl != core->ctrl)
+ clk_ctrl_prepare_unlock(child->ctrl);
+
+ clk_prepare_unlock_children_locked(child);
+ }
+}
+
+static void clk_prepare_unlock_children(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ /* Unlock the initial controller, skipped in children recurrency */
+ clk_ctrl_prepare_unlock(core->ctrl);
+ clk_prepare_unlock_children_locked(core);
+ clk_prepare_unlock();
+}
+
+/* Locks prepare lock, children and parents */
+static void clk_prepare_lock_tree(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_prepare_lock();
+ clk_prepare_lock_children_locked(core);
+ /* Children recurrency skiped locking first one */
+ clk_ctrl_prepare_lock(core->ctrl);
+ clk_prepare_lock_parents_locked(core);
+}
+
+static void clk_prepare_unlock_tree(struct clk_core *core)
+{
+ if (!core)
+ return;
+
+ clk_prepare_unlock_parents(core);
+ /* Unlock the initial controller, skipped in children recurrency */
+ clk_ctrl_prepare_unlock(core->ctrl);
+ clk_prepare_unlock_children_locked(core);
+ clk_prepare_unlock();
+}
+
+/*
+ * Unlocks the controller hierarchy (children and parents) but going from
+ * old parent. Used in case of reparenting.
+ * If (core->parent == old_parent), this is equal to clk_prepare_unlock_tree().
+ */
+static void clk_prepare_unlock_oldtree(struct clk_core *core,
+ struct clk_core *old_parent)
+{
+ if (!core)
+ return;
+
+ clk_prepare_unlock_parents(old_parent);
+ /*
+ * Lock parents was called on 'core', but we unlock starting from
+ * 'old_parent'. In the same time locking did not lock the same
+ * controller twice but this check will be skipped for 'core'.
+ */
+ if (old_parent->ctrl != core->ctrl)
+ clk_ctrl_prepare_unlock(core->ctrl);
+
+ /* Unlock the initial controller, skipped in children recurrency */
+ clk_ctrl_prepare_unlock(core->ctrl);
+ clk_prepare_unlock_children_locked(core);
+ clk_prepare_unlock();
+}
+
+/* Locks everything */
+/* FIXME: order of locking, it does not follow child-parent */
+static void clk_prepare_lock_all(void)
+{
+ struct clk_ctrl *ctrl;
+
+ clk_prepare_lock();
+ list_for_each_entry(ctrl, &clk_ctrl_list, node)
+ clk_ctrl_prepare_lock(ctrl);
+}
+
+static void clk_prepare_unlock_all(void)
+{
+ struct clk_ctrl *ctrl;
+
+ list_for_each_entry(ctrl, &clk_ctrl_list, node)
+ clk_ctrl_prepare_unlock(ctrl);
+ clk_prepare_unlock();
+}
+
static bool clk_core_is_prepared(struct clk_core *core)
{
/*
@@ -2526,6 +2768,34 @@ void __clk_free_clk(struct clk *clk)
kfree(clk);
}
+struct clk_ctrl *clk_ctrl_register(struct device *dev)
+{
+ struct clk_ctrl *ctrl;
+
+ ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
+ if (!ctrl)
+ return ERR_PTR(-ENOMEM);
+
+ mutex_init(&ctrl->prepare_lock);
+
+ clk_prepare_lock();
+ list_add(&ctrl->node, &clk_ctrl_list);
+ clk_prepare_unlock();
+
+ return ctrl;
+}
+EXPORT_SYMBOL_GPL(clk_ctrl_register);
+
+void clk_ctrl_unregister(struct clk_ctrl *ctrl)
+{
+ clk_prepare_lock();
+ list_del(&ctrl->node);
+ clk_prepare_unlock();
+
+ kfree(ctrl);
+}
+EXPORT_SYMBOL_GPL(clk_ctrl_unregister);
+
/**
* clk_register - allocate a new clock, register it and return an opaque cookie
* @dev: device that is registering this clock
@@ -2537,7 +2807,8 @@ void __clk_free_clk(struct clk *clk)
* rest of the clock API. In the event of an error clk_register will return an
* error code; drivers must test for an error code after calling clk_register.
*/
-struct clk *clk_register(struct device *dev, struct clk_hw *hw)
+struct clk *clk_register_with_ctrl(struct device *dev, struct clk_ctrl *ctrl,
+ struct clk_hw *hw)
{
int i, ret;
struct clk_core *core;
@@ -2561,6 +2832,10 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
core->num_parents = hw->init->num_parents;
core->min_rate = 0;
core->max_rate = ULONG_MAX;
+ if (ctrl)
+ core->ctrl = ctrl;
+ else
+ core->ctrl = &global_ctrl;
hw->core = core;
/* allocate local copy in case parent_names is __initdata */
@@ -2619,7 +2894,7 @@ fail_name:
fail_out:
return ERR_PTR(ret);
}
-EXPORT_SYMBOL_GPL(clk_register);
+EXPORT_SYMBOL_GPL(clk_register_with_ctrl);
/**
* clk_hw_register - register a clk_hw and return an error code
@@ -2631,11 +2906,12 @@ EXPORT_SYMBOL_GPL(clk_register);
* less than zero indicating failure. Drivers must test for an error code after
* calling clk_hw_register().
*/
-int clk_hw_register(struct device *dev, struct clk_hw *hw)
+int clk_hw_register_with_ctrl(struct device *dev, struct clk_ctrl *ctrl,
+ struct clk_hw *hw)
{
- return PTR_ERR_OR_ZERO(clk_register(dev, hw));
+ return PTR_ERR_OR_ZERO(clk_register_with_ctrl(dev, ctrl, hw));
}
-EXPORT_SYMBOL_GPL(clk_hw_register);
+EXPORT_SYMBOL_GPL(clk_hw_register_with_ctrl);
/* Free memory allocated for a clock. */
static void __clk_release(struct kref *ref)
@@ -2644,6 +2920,7 @@ static void __clk_release(struct kref *ref)
int i = core->num_parents;
lockdep_assert_held(&prepare_lock);
+ // lockdep_assert_not_held(&core->ctrl->prepare_lock); // TODO?
kfree(core->parents);
while (--i >= 0)
@@ -2767,7 +3044,7 @@ static void devm_clk_hw_release(struct device *dev, void *res)
* automatically clk_unregister()ed on driver detach. See clk_register() for
* more information.
*/
-struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
+struct clk *devm_clk_register_with_ctrl(struct device *dev, struct clk_ctrl *ctrl, struct clk_hw *hw)
{
struct clk *clk;
struct clk **clkp;
@@ -2776,7 +3053,7 @@ struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
if (!clkp)
return ERR_PTR(-ENOMEM);
- clk = clk_register(dev, hw);
+ clk = clk_register_with_ctrl(dev, ctrl, hw);
if (!IS_ERR(clk)) {
*clkp = clk;
devres_add(dev, clkp);
@@ -2786,7 +3063,7 @@ struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
return clk;
}
-EXPORT_SYMBOL_GPL(devm_clk_register);
+EXPORT_SYMBOL_GPL(devm_clk_register_with_ctrl);
/**
* devm_clk_hw_register - resource managed clk_hw_register()
@@ -2797,7 +3074,8 @@ EXPORT_SYMBOL_GPL(devm_clk_register);
* automatically clk_hw_unregister()ed on driver detach. See clk_hw_register()
* for more information.
*/
-int devm_clk_hw_register(struct device *dev, struct clk_hw *hw)
+int devm_clk_hw_register_with_ctrl(struct device *dev, struct clk_ctrl *ctrl,
+ struct clk_hw *hw)
{
struct clk_hw **hwp;
int ret;
@@ -2806,7 +3084,7 @@ int devm_clk_hw_register(struct device *dev, struct clk_hw *hw)
if (!hwp)
return -ENOMEM;
- ret = clk_hw_register(dev, hw);
+ ret = clk_hw_register_with_ctrl(dev, ctrl, hw);
if (!ret) {
*hwp = hw;
devres_add(dev, hwp);
@@ -2816,7 +3094,7 @@ int devm_clk_hw_register(struct device *dev, struct clk_hw *hw)
return ret;
}
-EXPORT_SYMBOL_GPL(devm_clk_hw_register);
+EXPORT_SYMBOL_GPL(devm_clk_hw_register_with_ctrl);
static int devm_clk_match(struct device *dev, void *res, void *data)
{
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index a39c0c530778..3589f164ff94 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -39,6 +39,7 @@
struct clk;
struct clk_hw;
struct clk_core;
+struct clk_ctrl;
struct dentry;
/**
@@ -703,6 +704,8 @@ struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name,
bool active_low, unsigned long flags);
void clk_hw_unregister_gpio_mux(struct clk_hw *hw);
+struct clk_ctrl *clk_ctrl_register(struct device *dev);
+void clk_ctrl_unregister(struct clk_ctrl *ctrl);
/**
* clk_register - allocate a new clock, register it and return an opaque cookie
* @dev: device that is registering this clock
@@ -714,11 +717,23 @@ void clk_hw_unregister_gpio_mux(struct clk_hw *hw);
* rest of the clock API. In the event of an error clk_register will return an
* error code; drivers must test for an error code after calling clk_register.
*/
-struct clk *clk_register(struct device *dev, struct clk_hw *hw);
-struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw);
-
-int __must_check clk_hw_register(struct device *dev, struct clk_hw *hw);
-int __must_check devm_clk_hw_register(struct device *dev, struct clk_hw *hw);
+struct clk *clk_register_with_ctrl(struct device *dev, struct clk_ctrl *ctrl,
+ struct clk_hw *hw);
+struct clk *devm_clk_register_with_ctrl(struct device *dev, struct clk_ctrl *ctrl,
+ struct clk_hw *hw);
+
+#define clk_register(dev, hw) clk_register_with_ctrl(dev, NULL, hw)
+#define devm_clk_register(dev, hw) devm_clk_register_with_ctrl(dev, NULL, hw)
+
+int __must_check clk_hw_register_with_ctrl(struct device *dev,
+ struct clk_ctrl *ctrl,
+ struct clk_hw *hw);
+int __must_check devm_clk_hw_register_with_ctrl(struct device *dev,
+ struct clk_ctrl *ctrl,
+ struct clk_hw *hw);
+
+#define clk_hw_register(dev, hw) clk_hw_register_with_ctrl(dev, NULL, hw)
+#define devm_clk_hw_register(dev, hw) devm_clk_hw_register_with_ctrl(dev, NULL, hw)
void clk_unregister(struct clk *clk);
void devm_clk_unregister(struct device *dev, struct clk *clk);
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 123c02788807..8f751d1eb1df 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -19,6 +19,7 @@
struct device;
struct clk;
+struct clk_ctrl;
/**
* DOC: clk notifier callback types
--
1.9.1
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