165 lines
5.4 KiB
Diff
165 lines
5.4 KiB
Diff
Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: [v3,04/13] clk: Add safe switch hook
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From: Stephen Boyd <sboyd@codeaurora.org>
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X-Patchwork-Id: 6063211
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Message-Id: <1426920332-9340-5-git-send-email-sboyd@codeaurora.org>
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To: Mike Turquette <mturquette@linaro.org>, Stephen Boyd <sboyd@codeaurora.org>
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Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
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linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
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Viresh Kumar <viresh.kumar@linaro.org>
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Date: Fri, 20 Mar 2015 23:45:23 -0700
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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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This patch is good enough for Krait, but soon I'll need to
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support a "safe rate" where we ask a clock what rate it needs to be running
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at to be sure it's within voltage constraints. Right now safe parent
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handles that problem on Krait, but on other platforms it won't work.
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drivers/clk/clk.c | 61 ++++++++++++++++++++++++++++++++++++++------
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include/linux/clk-provider.h | 1 +
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2 files changed, 54 insertions(+), 8 deletions(-)
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--- a/drivers/clk/clk.c
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+++ b/drivers/clk/clk.c
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@@ -56,9 +56,12 @@ struct clk_core {
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struct clk_core **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 req_rate;
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+ unsigned long old_rate;
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unsigned long new_rate;
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+ struct clk_core *safe_parent;
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struct clk_core *new_parent;
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struct clk_core *new_child;
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unsigned long flags;
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@@ -1596,7 +1599,8 @@ out:
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static void clk_calc_subtree(struct clk_core *clk, unsigned long new_rate,
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struct clk_core *new_parent, u8 p_index)
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{
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- struct clk_core *child;
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+ struct clk_core *child, *parent;
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+ struct clk_hw *parent_hw;
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clk->new_rate = new_rate;
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clk->new_parent = new_parent;
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@@ -1606,6 +1610,18 @@ static void clk_calc_subtree(struct clk_
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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_hw = clk->ops->get_safe_parent(clk->hw);
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+ if (parent_hw) {
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+ parent = parent_hw->core;
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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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child->new_rate = clk_recalc(child, new_rate);
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clk_calc_subtree(child, child->new_rate, NULL, 0);
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@@ -1710,14 +1726,43 @@ static struct clk_core *clk_propagate_ra
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unsigned long event)
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{
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struct clk_core *child, *tmp_clk, *fail_clk = NULL;
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+ struct clk_core *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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+ clk->old_rate = clk->rate;
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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 || clk->old_rate != clk->rate)
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+ ret = __clk_notify(clk, event, clk->old_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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@@ -1763,7 +1808,8 @@ clk_change_rate(struct clk_core *clk, un
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old_rate = clk->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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trace_clk_set_parent(clk, clk->new_parent);
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@@ -1789,9 +1835,6 @@ clk_change_rate(struct clk_core *clk, un
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clk->rate = clk->new_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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/*
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* Use safe iteration, as change_rate can actually swap parents
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* for certain clock types.
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@@ -1851,6 +1894,8 @@ static int clk_core_set_rate_nolock(stru
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clk->req_rate = req_rate;
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+ clk_propagate_rate_change(top, POST_RATE_CHANGE);
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+
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return ret;
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}
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--- a/include/linux/clk-provider.h
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+++ b/include/linux/clk-provider.h
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@@ -183,6 +183,7 @@ struct clk_ops {
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struct clk_hw **best_parent_hw);
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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_hw *(*get_safe_parent)(struct clk_hw *hw);
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int (*set_rate)(struct clk_hw *hw, unsigned long rate,
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unsigned long parent_rate);
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int (*set_rate_and_parent)(struct clk_hw *hw,
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