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156 lines
5.1 KiB
Diff
156 lines
5.1 KiB
Diff
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From b7b3ceec506179d59e46e3a8ea8b370872cc7fcb Mon Sep 17 00:00:00 2001
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From: Stephen Boyd <sboyd@codeaurora.org>
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Date: Mon, 31 Mar 2014 16:52:29 -0700
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Subject: [PATCH 126/182] clk: Add safe switch hook
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Sometimes clocks can't accept their parent source turning off
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while the source is reprogrammed to a different rate. Most
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notably CPU clocks require a way to switch away from the current
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PLL they're running on, reprogram that PLL to a new rate, and
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then switch back to the PLL with the new rate once they're done.
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Add a hook that drivers can implement allowing them to return a
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'safe parent' that they can switch their parent to while the
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upstream source is reprogrammed to support this.
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Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
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---
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drivers/clk/clk.c | 53 ++++++++++++++++++++++++++++++++++++------
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include/linux/clk-private.h | 2 ++
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include/linux/clk-provider.h | 1 +
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3 files changed, 49 insertions(+), 7 deletions(-)
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diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
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index b94a311..0582068 100644
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--- a/drivers/clk/clk.c
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+++ b/drivers/clk/clk.c
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@@ -1356,6 +1356,7 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
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struct clk *new_parent, u8 p_index)
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{
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struct clk *child;
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+ struct clk *parent;
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clk->new_rate = new_rate;
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clk->new_parent = new_parent;
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@@ -1365,6 +1366,17 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
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if (new_parent && new_parent != clk->parent)
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new_parent->new_child = clk;
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+ if (clk->ops->get_safe_parent) {
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+ parent = clk->ops->get_safe_parent(clk->hw);
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+ if (parent) {
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+ p_index = clk_fetch_parent_index(clk, parent);
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+ clk->safe_parent_index = p_index;
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+ clk->safe_parent = parent;
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+ }
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+ } else {
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+ clk->safe_parent = NULL;
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+ }
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+
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hlist_for_each_entry(child, &clk->children, child_node) {
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if (child->ops->recalc_rate)
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child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
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@@ -1450,14 +1462,42 @@ out:
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static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
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{
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struct clk *child, *tmp_clk, *fail_clk = NULL;
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+ struct clk *old_parent;
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int ret = NOTIFY_DONE;
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- if (clk->rate == clk->new_rate)
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+ if (clk->rate == clk->new_rate && event != POST_RATE_CHANGE)
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return NULL;
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+ switch (event) {
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+ case PRE_RATE_CHANGE:
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+ if (clk->safe_parent)
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+ clk->ops->set_parent(clk->hw, clk->safe_parent_index);
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+ break;
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+ case POST_RATE_CHANGE:
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+ if (clk->safe_parent) {
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+ old_parent = __clk_set_parent_before(clk,
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+ clk->new_parent);
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+ if (clk->ops->set_rate_and_parent) {
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+ clk->ops->set_rate_and_parent(clk->hw,
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+ clk->new_rate,
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+ clk->new_parent ?
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+ clk->new_parent->rate : 0,
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+ clk->new_parent_index);
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+ } else if (clk->ops->set_parent) {
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+ clk->ops->set_parent(clk->hw,
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+ clk->new_parent_index);
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+ }
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+ __clk_set_parent_after(clk, clk->new_parent,
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+ old_parent);
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+ }
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+ break;
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+ }
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+
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if (clk->notifier_count) {
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- ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
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- if (ret & NOTIFY_STOP_MASK)
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+ if (event != POST_RATE_CHANGE)
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+ ret = __clk_notify(clk, event, clk->rate,
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+ clk->new_rate);
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+ if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
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fail_clk = clk;
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}
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@@ -1499,7 +1539,8 @@ static void clk_change_rate(struct clk *clk)
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else if (clk->parent)
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best_parent_rate = clk->parent->rate;
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- if (clk->new_parent && clk->new_parent != clk->parent) {
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+ if (clk->new_parent && clk->new_parent != clk->parent &&
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+ !clk->safe_parent) {
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old_parent = __clk_set_parent_before(clk, clk->new_parent);
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if (clk->ops->set_rate_and_parent) {
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@@ -1522,9 +1563,6 @@ static void clk_change_rate(struct clk *clk)
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else
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clk->rate = best_parent_rate;
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- if (clk->notifier_count && old_rate != clk->rate)
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- __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
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-
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hlist_for_each_entry(child, &clk->children, child_node) {
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/* Skip children who will be reparented to another clock */
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if (child->new_parent && child->new_parent != clk)
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@@ -1598,6 +1636,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
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/* change the rates */
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clk_change_rate(top);
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+ clk_propagate_rate_change(top, POST_RATE_CHANGE);
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out:
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clk_prepare_unlock();
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diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
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index efbf70b..f48684a 100644
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--- a/include/linux/clk-private.h
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+++ b/include/linux/clk-private.h
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@@ -38,8 +38,10 @@ struct clk {
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struct clk **parents;
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u8 num_parents;
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u8 new_parent_index;
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+ u8 safe_parent_index;
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unsigned long rate;
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unsigned long new_rate;
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+ struct clk *safe_parent;
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struct clk *new_parent;
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struct clk *new_child;
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unsigned long flags;
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diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
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index 939533d..300fcb8 100644
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--- a/include/linux/clk-provider.h
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+++ b/include/linux/clk-provider.h
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@@ -157,6 +157,7 @@ struct clk_ops {
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struct clk **best_parent_clk);
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int (*set_parent)(struct clk_hw *hw, u8 index);
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u8 (*get_parent)(struct clk_hw *hw);
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+ struct clk *(*get_safe_parent)(struct clk_hw *hw);
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int (*set_rate)(struct clk_hw *hw, unsigned long,
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unsigned long);
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int (*set_rate_and_parent)(struct clk_hw *hw,
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--
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1.7.10.4
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