mirror of https://github.com/hak5/openwrt-owl.git
152 lines
4.9 KiB
Diff
152 lines
4.9 KiB
Diff
From f7a00ea959be31f9b742042294a359d508edce94 Mon Sep 17 00:00:00 2001
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From: Stephen Boyd <sboyd@codeaurora.org>
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Date: Fri, 20 Mar 2015 23:45:23 -0700
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Subject: [PATCH] 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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Signed-off-by: Ram Chandra Jangir <rjangi@codeaurora.org>
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---
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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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@@ -51,9 +51,12 @@ 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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@@ -1271,7 +1274,8 @@ out:
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static void clk_calc_subtree(struct clk_core *core, 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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core->new_rate = new_rate;
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core->new_parent = new_parent;
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@@ -1281,6 +1285,18 @@ static void clk_calc_subtree(struct clk_
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if (new_parent && new_parent != core->parent)
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new_parent->new_child = core;
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+ if (core->ops->get_safe_parent) {
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+ parent_hw = core->ops->get_safe_parent(core->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(core, parent);
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+ core->safe_parent_index = p_index;
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+ core->safe_parent = parent;
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+ }
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+ } else {
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+ core->safe_parent = NULL;
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+ }
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+
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hlist_for_each_entry(child, &core->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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@@ -1393,14 +1409,43 @@ 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 (core->rate == core->new_rate)
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+ if (core->rate == core->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 (core->safe_parent)
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+ core->ops->set_parent(core->hw, core->safe_parent_index);
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+ core->old_rate = core->rate;
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+ break;
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+ case POST_RATE_CHANGE:
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+ if (core->safe_parent) {
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+ old_parent = __clk_set_parent_before(core,
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+ core->new_parent);
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+ if (core->ops->set_rate_and_parent) {
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+ core->ops->set_rate_and_parent(core->hw,
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+ core->new_rate,
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+ core->new_parent ?
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+ core->new_parent->rate : 0,
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+ core->new_parent_index);
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+ } else if (core->ops->set_parent) {
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+ core->ops->set_parent(core->hw,
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+ core->new_parent_index);
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+ }
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+ __clk_set_parent_after(core, core->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 (core->notifier_count) {
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- ret = __clk_notify(core, event, core->rate, core->new_rate);
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- if (ret & NOTIFY_STOP_MASK)
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+ if (event != POST_RATE_CHANGE || core->old_rate != core->rate)
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+ ret = __clk_notify(core, event, core->old_rate,
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+ core->new_rate);
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+ if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
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fail_clk = core;
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}
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@@ -1446,7 +1491,8 @@ clk_change_rate(struct clk_core *core, u
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old_rate = core->rate;
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- if (core->new_parent && core->new_parent != core->parent) {
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+ if (core->new_parent && core->new_parent != core->parent &&
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+ !core->safe_parent) {
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old_parent = __clk_set_parent_before(core, core->new_parent);
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trace_clk_set_parent(core, core->new_parent);
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@@ -1472,9 +1518,6 @@ clk_change_rate(struct clk_core *core, u
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core->rate = core->new_rate;
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- if (core->notifier_count && old_rate != core->rate)
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- __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);
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-
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if (core->flags & CLK_RECALC_NEW_RATES)
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(void)clk_calc_new_rates(core, core->new_rate);
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@@ -1537,6 +1580,8 @@ static int clk_core_set_rate_nolock(stru
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core->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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@@ -202,6 +202,7 @@ struct clk_ops {
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struct clk_rate_request *req);
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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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