+++ /dev/null
-Content-Type: text/plain; charset="utf-8"
-MIME-Version: 1.0
-Content-Transfer-Encoding: 7bit
-Subject: [v3,04/13] clk: Add safe switch hook
-From: Stephen Boyd <sboyd@codeaurora.org>
-X-Patchwork-Id: 6063211
-Message-Id: <1426920332-9340-5-git-send-email-sboyd@codeaurora.org>
-To: Mike Turquette <mturquette@linaro.org>, Stephen Boyd <sboyd@codeaurora.org>
-Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
- linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
- Viresh Kumar <viresh.kumar@linaro.org>
-Date: Fri, 20 Mar 2015 23:45:23 -0700
-
-Sometimes clocks can't accept their parent source turning off
-while the source is reprogrammed to a different rate. Most
-notably CPU clocks require a way to switch away from the current
-PLL they're running on, reprogram that PLL to a new rate, and
-then switch back to the PLL with the new rate once they're done.
-Add a hook that drivers can implement allowing them to return a
-'safe parent' that they can switch their parent to while the
-upstream source is reprogrammed to support this.
-
-Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
-
----
-This patch is good enough for Krait, but soon I'll need to
-support a "safe rate" where we ask a clock what rate it needs to be running
-at to be sure it's within voltage constraints. Right now safe parent
-handles that problem on Krait, but on other platforms it won't work.
-
- drivers/clk/clk.c | 61 ++++++++++++++++++++++++++++++++++++++------
- include/linux/clk-provider.h | 1 +
- 2 files changed, 54 insertions(+), 8 deletions(-)
-
---- a/drivers/clk/clk.c
-+++ b/drivers/clk/clk.c
-@@ -1350,7 +1350,8 @@ out:
- static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
- struct clk *new_parent, u8 p_index)
- {
-- struct clk *child;
-+ struct clk *child, *parent;
-+ struct clk_hw *parent_hw;
-
- clk->new_rate = new_rate;
- clk->new_parent = new_parent;
-@@ -1360,6 +1361,18 @@ static void clk_calc_subtree(struct clk
- if (new_parent && new_parent != clk->parent)
- new_parent->new_child = clk;
-
-+ if (clk->ops->get_safe_parent) {
-+ parent_hw = clk->ops->get_safe_parent(clk->hw);
-+ if (parent_hw) {
-+ parent = parent_hw->clk;
-+ p_index = clk_fetch_parent_index(clk, parent);
-+ clk->safe_parent_index = p_index;
-+ clk->safe_parent = parent;
-+ }
-+ } else {
-+ clk->safe_parent = NULL;
-+ }
-+
- hlist_for_each_entry(child, &clk->children, child_node) {
- child->new_rate = clk_recalc(child, new_rate);
- clk_calc_subtree(child, child->new_rate, NULL, 0);
-@@ -1439,17 +1452,47 @@ out:
- * so that in case of an error we can walk down the whole tree again and
- * abort the change.
- */
--static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
-+static struct clk *clk_propagate_rate_change(struct clk *clk,
-+ unsigned long event)
- {
- struct clk *child, *tmp_clk, *fail_clk = NULL;
-+ struct clk *old_parent;
- int ret = NOTIFY_DONE;
-
-- if (clk->rate == clk->new_rate)
-+ if (clk->rate == clk->new_rate && event != POST_RATE_CHANGE)
- return NULL;
-
-+ switch (event) {
-+ case PRE_RATE_CHANGE:
-+ if (clk->safe_parent)
-+ clk->ops->set_parent(clk->hw, clk->safe_parent_index);
-+ clk->old_rate = clk->rate;
-+ break;
-+ case POST_RATE_CHANGE:
-+ if (clk->safe_parent) {
-+ old_parent = __clk_set_parent_before(clk,
-+ clk->new_parent);
-+ if (clk->ops->set_rate_and_parent) {
-+ clk->ops->set_rate_and_parent(clk->hw,
-+ clk->new_rate,
-+ clk->new_parent ?
-+ clk->new_parent->rate : 0,
-+ clk->new_parent_index);
-+ } else if (clk->ops->set_parent) {
-+ clk->ops->set_parent(clk->hw,
-+ clk->new_parent_index);
-+ }
-+ __clk_set_parent_after(clk, clk->new_parent,
-+ old_parent);
-+ }
-+ break;
-+ }
-+
- if (clk->notifier_count) {
-- ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
-- if (ret & NOTIFY_STOP_MASK)
-+ if (event != POST_RATE_CHANGE || clk->old_rate != clk->rate)
-+ ret = __clk_notify(clk, event, clk->old_rate,
-+ clk->new_rate);
-+ if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
- fail_clk = clk;
- }
-
-@@ -1494,7 +1537,8 @@ static void clk_change_rate(struct clk *
-
- old_rate = clk->rate;
-
-- if (clk->new_parent && clk->new_parent != clk->parent) {
-+ if (clk->new_parent && clk->new_parent != clk->parent &&
-+ !clk->safe_parent) {
- old_parent = __clk_set_parent_before(clk, clk->new_parent);
-
- if (clk->ops->set_rate_and_parent) {
-@@ -1514,9 +1558,6 @@ static void clk_change_rate(struct clk *
-
- clk->rate = clk->new_rate;
-
-- if (clk->notifier_count && old_rate != clk->rate)
-- __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
--
- /*
- * Use safe iteration, as change_rate can actually swap parents
- * for certain clock types.
-@@ -1601,6 +1642,8 @@ int clk_set_rate(struct clk *clk, unsign
- /* change the rates */
- clk_change_rate(top, parent_rate);
-
-+ clk_propagate_rate_change(top, POST_RATE_CHANGE);
-+
- out:
- clk_prepare_unlock();
-
---- a/include/linux/clk-provider.h
-+++ b/include/linux/clk-provider.h
-@@ -179,6 +179,7 @@ struct clk_ops {
- struct clk **best_parent_clk);
- int (*set_parent)(struct clk_hw *hw, u8 index);
- u8 (*get_parent)(struct clk_hw *hw);
-+ struct clk_hw *(*get_safe_parent)(struct clk_hw *hw);
- int (*set_rate)(struct clk_hw *hw, unsigned long rate,
- unsigned long parent_rate);
- int (*set_rate_and_parent)(struct clk_hw *hw,
---- a/include/linux/clk-private.h
-+++ b/include/linux/clk-private.h
-@@ -38,8 +38,11 @@ struct clk {
- struct clk **parents;
- u8 num_parents;
- u8 new_parent_index;
-+ u8 safe_parent_index;
- unsigned long rate;
-+ unsigned long old_rate;
- unsigned long new_rate;
-+ struct clk *safe_parent;
- struct clk *new_parent;
- struct clk *new_child;
- unsigned long flags;
projects / openwrt / staging / lynxis / omap.git / blobdiff