Add support for automatic selection of the best parent for a mux, i.e. the one which can provide the closest clock rate to that requested. This is by way of adding a parameter to the round_rate clock op which allows the clock to optionally select a different parent index. This is used in clk_calc_new_rates to decide whether to initiate a set_parent operation.
This splits out the mutex protected portion of clk_set_parent() into a separate __clk_set_parent_notify() which takes care of sending clock change notifications. A new clock flag is also added called CLK_SET_RATE_REMUX to indicate that the clock can have it's parent changed automatically in response to a set_rate. It isn't used yet, but will be used within clock mux drivers. Signed-off-by: James Hogan <[email protected]> --- drivers/clk/clk.c | 94 +++++++++++++++++++++++++++++++------------- include/linux/clk-provider.h | 6 ++- 2 files changed, 71 insertions(+), 29 deletions(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 79d5deb..3886ccd 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -36,6 +36,8 @@ static struct dentry *rootdir; static struct dentry *orphandir; static int inited = 0; +static int __clk_set_parent_notify(struct clk *clk, struct clk *parent); + static void clk_summary_show_one(struct seq_file *s, struct clk *c, int level) { if (!c) @@ -737,7 +739,7 @@ unsigned long __clk_round_rate(struct clk *clk, unsigned long rate) if (clk->parent) parent_rate = clk->parent->rate; - return clk->ops->round_rate(clk->hw, rate, &parent_rate); + return clk->ops->round_rate(clk->hw, rate, &parent_rate, NULL); } /** @@ -928,8 +930,10 @@ 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 *parent; unsigned long best_parent_rate = 0; unsigned long new_rate; + u8 old_parent = 0, best_parent; /* sanity */ if (IS_ERR_OR_NULL(clk)) @@ -939,13 +943,21 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate) if (clk->parent) best_parent_rate = clk->parent->rate; + /* by default don't change the parent */ + if (clk->ops->get_parent) + old_parent = clk->ops->get_parent(clk->hw); + best_parent = old_parent; + parent = clk->parent; + /* 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); + new_rate = clk->ops->round_rate(clk->hw, rate, + &best_parent_rate, + &best_parent); goto out; } @@ -962,15 +974,36 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate) goto out; } - new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate); + new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate, + &best_parent); - if (best_parent_rate != clk->parent->rate) { - top = clk_calc_new_rates(clk->parent, best_parent_rate); + if (best_parent != old_parent) { + parent = __clk_get_parent_by_index(clk, best_parent); + /* couldn't find requested parent */ + if (!parent) + return NULL; + } + + if (best_parent_rate != parent->rate) { + top = clk_calc_new_rates(parent, best_parent_rate); goto out; } out: + /* the parent may have changed */ + if (best_parent != old_parent) { + parent = __clk_get_parent_by_index(clk, best_parent); + /* couldn't find requested parent */ + if (!parent) { + parent = clk->parent; + best_parent = old_parent; + } + if (best_parent != old_parent) + if (__clk_set_parent_notify(clk, parent)) + return NULL; + } + clk_calc_subtree(clk, new_rate); return top; @@ -1270,31 +1303,10 @@ out: return ret; } -/** - * clk_set_parent - switch the parent of a mux clk - * @clk: the mux clk whose input we are switching - * @parent: the new input to clk - * - * Re-parent clk to use parent as it's new input source. If clk has the - * CLK_SET_PARENT_GATE flag set then clk must be gated for this - * operation to succeed. After successfully changing clk's parent - * clk_set_parent will update the clk topology, sysfs topology and - * propagate rate recalculation via __clk_recalc_rates. Returns 0 on - * success, -EERROR otherwise. - */ -int clk_set_parent(struct clk *clk, struct clk *parent) +static int __clk_set_parent_notify(struct clk *clk, struct clk *parent) { int ret = 0; - if (!clk || !clk->ops) - return -EINVAL; - - if (!clk->ops->set_parent) - return -ENOSYS; - - /* prevent racing with updates to the clock topology */ - mutex_lock(&prepare_lock); - if (clk->parent == parent) goto out; @@ -1322,6 +1334,34 @@ int clk_set_parent(struct clk *clk, struct clk *parent) __clk_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 + * @parent: the new input to clk + * + * Re-parent clk to use parent as it's new input source. If clk has the + * CLK_SET_PARENT_GATE flag set then clk must be gated for this + * operation to succeed. After successfully changing clk's parent + * clk_set_parent will update the clk topology, sysfs topology and + * propagate rate recalculation via __clk_recalc_rates. Returns 0 on + * success, -EERROR otherwise. + */ +int clk_set_parent(struct clk *clk, struct clk *parent) +{ + int ret; + + if (!clk || !clk->ops) + return -EINVAL; + + if (!clk->ops->set_parent) + return -ENOSYS; + + /* prevent racing with updates to the clock topology */ + mutex_lock(&prepare_lock); + ret = __clk_set_parent_notify(clk, parent); mutex_unlock(&prepare_lock); return ret; diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 4e0b634..cdad3ce 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -27,6 +27,7 @@ #define CLK_IS_ROOT BIT(4) /* root clk, has no parent */ #define CLK_IS_BASIC BIT(5) /* Basic clk, can't do a to_clk_foo() */ #define CLK_GET_RATE_NOCACHE BIT(6) /* do not use the cached clk rate */ +#define CLK_SET_RATE_REMUX BIT(7) /* find best parent for rate change */ struct clk_hw; @@ -69,7 +70,8 @@ struct clk_hw; * this op is not set then clock rate will be initialized to 0. * * @round_rate: Given a target rate as input, returns the closest rate actually - * supported by the clock. + * supported by the clock, and optionally the index of the parent + * 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 @@ -115,7 +117,7 @@ struct clk_ops { unsigned long (*recalc_rate)(struct clk_hw *hw, unsigned long parent_rate); long (*round_rate)(struct clk_hw *hw, unsigned long, - unsigned long *); + unsigned long *, u8 *index); 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, -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
