@@ -70,6 +70,10 @@ the operations defined in clk.h:
unsigned long parent_rate);
long (*round_rate)(struct clk_hw *hw, unsigned long,
unsigned long *);
+ long (*determine_rate)(struct clk_hw *hw,
+ unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk **best_parent_clk);
int (*set_parent)(struct clk_hw *hw, u8 index);
u8 (*get_parent)(struct clk_hw *hw);
int (*set_rate)(struct clk_hw *hw, unsigned long);
@@ -34,6 +34,9 @@ static HLIST_HEAD(clk_root_list);
static HLIST_HEAD(clk_orphan_list);
static LIST_HEAD(clk_notifier_list);
+static int __clk_set_parent_no_recalc(struct clk *clk, struct clk *parent,
+ u8 p_index);
+
/*** locking ***/
static void clk_prepare_lock(void)
{
@@ -892,17 +895,20 @@ unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
if (!clk)
return 0;
- if (!clk->ops->round_rate) {
- if (clk->flags & CLK_SET_RATE_PARENT)
- return __clk_round_rate(clk->parent, rate);
- else
- return clk->rate;
- }
if (clk->parent)
parent_rate = clk->parent->rate;
- return clk->ops->round_rate(clk->hw, rate, &parent_rate);
+ if (clk->ops->determine_rate)
+ return clk->ops->determine_rate(clk->hw, rate, &parent_rate,
+ NULL);
+ else if (clk->ops->round_rate)
+ return clk->ops->round_rate(clk->hw, rate, &parent_rate);
+ else if (clk->flags & CLK_SET_RATE_PARENT)
+ return __clk_round_rate(clk->parent, rate);
+ else
+ return clk->rate;
+
}
/**
@@ -1027,6 +1033,32 @@ unsigned long clk_get_rate(struct clk *clk)
}
EXPORT_SYMBOL_GPL(clk_get_rate);
+static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)
+{
+ u8 i;
+
+ if (!clk->parents)
+ clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
+ GFP_KERNEL);
+
+ /*
+ * find index of new parent clock using cached parent ptrs,
+ * or if not yet cached, use string name comparison and cache
+ * them now to avoid future calls to __clk_lookup.
+ */
+ for (i = 0; i < clk->num_parents; i++) {
+ if (clk->parents && clk->parents[i] == parent)
+ break;
+ else if (!strcmp(clk->parent_names[i], parent->name)) {
+ if (clk->parents)
+ clk->parents[i] = __clk_lookup(parent->name);
+ break;
+ }
+ }
+
+ return i;
+}
+
/**
* __clk_speculate_rates
* @clk: first clk in the subtree
@@ -1071,18 +1103,24 @@ out:
return ret;
}
-static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
+static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
+ struct clk *new_parent, u8 p_index)
{
struct clk *child;
clk->new_rate = new_rate;
+ clk->new_parent = new_parent;
+ clk->new_parent_index = p_index;
+ clk->new_child = NULL;
+ if (new_parent && new_parent != clk->parent)
+ new_parent->new_child = clk;
hlist_for_each_entry(child, &clk->children, child_node) {
if (child->ops->recalc_rate)
child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
else
child->new_rate = new_rate;
- clk_calc_subtree(child, child->new_rate);
+ clk_calc_subtree(child, child->new_rate, NULL, 0);
}
}
@@ -1093,50 +1131,63 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
{
struct clk *top = clk;
+ struct clk *old_parent, *parent;
unsigned long best_parent_rate = 0;
unsigned long new_rate;
+ u8 p_index = 0;
/* sanity */
if (IS_ERR_OR_NULL(clk))
return NULL;
/* save parent rate, if it exists */
- if (clk->parent)
- best_parent_rate = clk->parent->rate;
-
- /* never propagate up to the parent */
- if (!(clk->flags & CLK_SET_RATE_PARENT)) {
- if (!clk->ops->round_rate) {
- clk->new_rate = clk->rate;
- return NULL;
- }
- new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
+ parent = old_parent = clk->parent;
+ if (parent)
+ best_parent_rate = parent->rate;
+
+ /* find the closest rate and parent clk/rate */
+ if (clk->ops->determine_rate) {
+ new_rate = clk->ops->determine_rate(clk->hw, rate,
+ &best_parent_rate,
+ &parent);
+ } else if (clk->ops->round_rate) {
+ new_rate = clk->ops->round_rate(clk->hw, rate,
+ &best_parent_rate);
+ } else if (!parent || !(clk->flags & CLK_SET_RATE_PARENT)) {
+ /* pass-through clock without adjustable parent */
+ clk->new_rate = clk->rate;
+ return NULL;
+ } else {
+ /* pass-through clock with adjustable parent */
+ top = clk_calc_new_rates(parent, rate);
+ new_rate = parent->new_rate;
goto out;
}
- /* need clk->parent from here on out */
- if (!clk->parent) {
- pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
+ /* some clocks must be gated to change parent */
+ if (parent != old_parent &&
+ (clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) {
+ pr_debug("%s: %s not gated but wants to reparent\n",
+ __func__, clk->name);
return NULL;
}
- if (!clk->ops->round_rate) {
- top = clk_calc_new_rates(clk->parent, rate);
- new_rate = clk->parent->new_rate;
-
- goto out;
+ /* try finding the new parent index */
+ if (parent) {
+ p_index = clk_fetch_parent_index(clk, parent);
+ if (p_index == clk->num_parents) {
+ pr_debug("%s: clk %s can not be parent of clk %s\n",
+ __func__, parent->name, clk->name);
+ return NULL;
+ }
}
- new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
-
- if (best_parent_rate != clk->parent->rate) {
- top = clk_calc_new_rates(clk->parent, best_parent_rate);
-
- goto out;
- }
+ if ((clk->flags & CLK_SET_RATE_PARENT) && parent &&
+ best_parent_rate != parent->rate)
+ top = clk_calc_new_rates(parent, best_parent_rate);
out:
- clk_calc_subtree(clk, new_rate);
+ clk_calc_subtree(clk, new_rate, parent, p_index);
return top;
}
@@ -1148,7 +1199,7 @@ out:
*/
static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
{
- struct clk *child, *fail_clk = NULL;
+ struct clk *child, *tmp_clk, *fail_clk = NULL;
int ret = NOTIFY_DONE;
if (clk->rate == clk->new_rate)
@@ -1161,9 +1212,19 @@ static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long even
}
hlist_for_each_entry(child, &clk->children, child_node) {
- clk = clk_propagate_rate_change(child, event);
- if (clk)
- fail_clk = clk;
+ /* Skip children who will be reparented to another clock */
+ if (child->new_parent && child->new_parent != clk)
+ continue;
+ tmp_clk = clk_propagate_rate_change(child, event);
+ if (tmp_clk)
+ fail_clk = tmp_clk;
+ }
+
+ /* handle the new child who might not be in clk->children yet */
+ if (clk->new_child) {
+ tmp_clk = clk_propagate_rate_change(clk->new_child, event);
+ if (tmp_clk)
+ fail_clk = tmp_clk;
}
return fail_clk;
@@ -1181,6 +1242,11 @@ static void clk_change_rate(struct clk *clk)
old_rate = clk->rate;
+ /* set parent */
+ if (clk->new_parent && clk->new_parent != clk->parent)
+ __clk_set_parent_no_recalc(clk, clk->new_parent,
+ clk->new_parent_index);
+
if (clk->parent)
best_parent_rate = clk->parent->rate;
@@ -1195,8 +1261,15 @@ static void clk_change_rate(struct clk *clk)
if (clk->notifier_count && old_rate != clk->rate)
__clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
- hlist_for_each_entry(child, &clk->children, child_node)
+ hlist_for_each_entry(child, &clk->children, child_node) {
+ /* Skip children who will be reparented to another clock */
+ if (child->new_parent && child->new_parent != clk)
+ continue;
clk_change_rate(child);
+ }
+
+ if (clk->new_child)
+ clk_change_rate(clk->new_child);
}
/**
@@ -1336,6 +1409,9 @@ out:
static void clk_reparent(struct clk *clk, struct clk *new_parent)
{
+ if (new_parent->new_child == clk)
+ new_parent->new_child = NULL;
+
hlist_del(&clk->child_node);
if (new_parent)
@@ -1353,32 +1429,6 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
__clk_recalc_rates(clk, POST_RATE_CHANGE);
}
-static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)
-{
- u8 i;
-
- if (!clk->parents)
- clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
- GFP_KERNEL);
-
- /*
- * find index of new parent clock using cached parent ptrs,
- * or if not yet cached, use string name comparison and cache
- * them now to avoid future calls to __clk_lookup.
- */
- for (i = 0; i < clk->num_parents; i++) {
- if (clk->parents && clk->parents[i] == parent)
- break;
- else if (!strcmp(clk->parent_names[i], parent->name)) {
- if (clk->parents)
- clk->parents[i] = __clk_lookup(parent->name);
- break;
- }
- }
-
- return i;
-}
-
static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index)
{
unsigned long flags;
@@ -1451,6 +1501,27 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index)
return 0;
}
+static int __clk_set_parent_no_recalc(struct clk *clk, struct clk *parent,
+ u8 p_index)
+{
+ int ret = 0;
+
+ if (clk->parent == parent)
+ goto out;
+
+ /* only re-parent if the clock is not in use */
+ ret = __clk_set_parent(clk, parent, p_index);
+ if (ret)
+ goto out;
+
+ /* reparent, but don't propagate rate recalculation downstream */
+ clk_reparent(clk, parent);
+ clk_debug_reparent(clk, parent);
+
+out:
+ return ret;
+}
+
/**
* clk_set_parent - switch the parent of a mux clk
* @clk: the mux clk whose input we are switching
@@ -1553,8 +1624,9 @@ int __clk_init(struct device *dev, struct clk *clk)
/* check that clk_ops are sane. See Documentation/clk.txt */
if (clk->ops->set_rate &&
- !(clk->ops->round_rate && clk->ops->recalc_rate)) {
- pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
+ !((clk->ops->round_rate || clk->ops->determine_rate) &&
+ clk->ops->recalc_rate)) {
+ pr_warning("%s: %s must implement .round_rate or .determine_rate in addition to .recalc_rate\n",
__func__, clk->name);
ret = -EINVAL;
goto out;
@@ -33,8 +33,11 @@ struct clk {
const char **parent_names;
struct clk **parents;
u8 num_parents;
+ u8 new_parent_index;
unsigned long rate;
unsigned long new_rate;
+ struct clk *new_parent;
+ struct clk *new_child;
unsigned long flags;
unsigned int enable_count;
unsigned int prepare_count;
@@ -79,6 +79,10 @@ struct clk_hw;
* @round_rate: Given a target rate as input, returns the closest rate actually
* supported by the clock.
*
+ * @determine_rate: Given a target rate as input, returns the closest rate
+ * actually supported by the clock, and optionally the parent clock
+ * that should be used to provide the clock rate.
+ *
* @get_parent: Queries the hardware to determine the parent of a clock. The
* return value is a u8 which specifies the index corresponding to
* the parent clock. This index can be applied to either the
@@ -126,6 +130,9 @@ struct clk_ops {
unsigned long parent_rate);
long (*round_rate)(struct clk_hw *hw, unsigned long,
unsigned long *);
+ long (*determine_rate)(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk **best_parent_clk);
int (*set_parent)(struct clk_hw *hw, u8 index);
u8 (*get_parent)(struct clk_hw *hw);
int (*set_rate)(struct clk_hw *hw, unsigned long,
Add core support to allow clock implementations to select the best parent clock when rounding a rate, e.g. the one which can provide the closest clock rate to that requested. This is by way of adding a new clock op, determine_rate(), which is like round_rate() but has an extra parameter to allow the clock implementation to optionally select a different parent clock. The core then takes care of reparenting the clock when setting the rate. The parent change takes place with the help of two new private data members. struct clk::new_parent specifies a clock's new parent (NULL indicates no change), and struct clk::new_child specifies a clock's new child (whose new_parent member points back to it). The purpose of these are to allow correct walking of the future tree for notifications prior to actually reparenting any clocks, specifically to skip child clocks who are being reparented to another clock (they will be notified via the new parent), and to include any new child clock. These pointers are set by clk_calc_subtree(), and the new_child pointer gets cleared when a child is actually reparented to avoid duplicate POST_RATE_CHANGE notifications. Each place where round_rate() is called, determine_rate is checked first and called in preference, passing NULL to the new parent argument if not needed (e.g. in __clk_round_rate). This restructures a few of the call sites to simplify the logic into if/else blocks. A new __clk_set_parent_no_recalc() is created similar to clk_set_parent() but without calling __clk_recalc_rates(). This is for clk_change_rate() to use, where rate recalculation and notifications are already handled. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Mike Turquette <mturquette@linaro.org> Cc: linux-arm-kernel@lists.infradead.org --- Changes in v3: * rebased on v3.10-rc1 * store new_parent_index in struct clk too (calculated from clk_fetch_parent_index, and passed through __clk_set_parent_no_recalc to __clk_set_parent). * allow determine_rate to satisfy recalc_rate check in __clk_init. Documentation/clk.txt | 4 + drivers/clk/clk.c | 208 +++++++++++++++++++++++++++++-------------- include/linux/clk-private.h | 3 + include/linux/clk-provider.h | 7 ++ 4 files changed, 154 insertions(+), 68 deletions(-)