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clk: core: support clocks which requires parents enable (part 2) 

On Freescale i.MX7D platform, all clocks operations, including
enable/disable, rate change and re-parent, requires its parent clock on.
Current clock core can not support it well.
This patch adding flag CLK_OPS_PARENT_ENABLE to handle this special case in
clock core that enable its parent clock firstly for each operation and
disable it later after operation complete.

The patch part 2 fixes set clock rate and set parent while its parent
is off. The most special case is for set_parent() operation which requires
all parents including both old and new one to be enabled at the same time
during the operation.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
[sboyd@codeaurora.org: Move set_rate tracepoint after prepare_enable]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
This commit is contained in:
Dong Aisheng 2016-06-30 17:31:14 +08:00 committed by Stephen Boyd
parent a4b3518d14
commit fc8726a2c0
1 changed files with 33 additions and 15 deletions
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48
drivers/clk/clk.c
View File

@ -1172,7 +1172,9 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core,
struct clk_core *old_parent = core->parent;
/*
* Migrate prepare state between parents and prevent race with
* 1. enable parents for CLK_OPS_PARENT_ENABLE clock
*
* 2. Migrate prepare state between parents and prevent race with
* clk_enable().
*
* If the clock is not prepared, then a race with
@ -1188,12 +1190,17 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core,
*
* See also: Comment for clk_set_parent() below.
*/
/* enable old_parent & parent if CLK_OPS_PARENT_ENABLE is set */
if (core->flags & CLK_OPS_PARENT_ENABLE) {
clk_core_prepare_enable(old_parent);
clk_core_prepare_enable(parent);
}
/* migrate prepare count if > 0 */
if (core->prepare_count) {
clk_core_prepare(parent);
flags = clk_enable_lock();
clk_core_enable(parent);
clk_core_enable(core);
clk_enable_unlock(flags);
clk_core_prepare_enable(parent);
clk_core_enable_lock(core);
}
/* update the clk tree topology */
@ -1208,18 +1215,19 @@ static void __clk_set_parent_after(struct clk_core *core,
struct clk_core *parent,
struct clk_core *old_parent)
{
unsigned long flags;
/*
* Finish the migration of prepare state and undo the changes done
* for preventing a race with clk_enable().
*/
if (core->prepare_count) {
flags = clk_enable_lock();
clk_core_disable(core);
clk_core_disable(old_parent);
clk_enable_unlock(flags);
clk_core_unprepare(old_parent);
clk_core_disable_lock(core);
clk_core_disable_unprepare(old_parent);
}
/* re-balance ref counting if CLK_OPS_PARENT_ENABLE is set */
if (core->flags & CLK_OPS_PARENT_ENABLE) {
clk_core_disable_unprepare(parent);
clk_core_disable_unprepare(old_parent);
}
}
@ -1466,13 +1474,17 @@ static void clk_change_rate(struct clk_core *core)
unsigned long best_parent_rate = 0;
bool skip_set_rate = false;
struct clk_core *old_parent;
struct clk_core *parent = NULL;
old_rate = core->rate;
if (core->new_parent)
if (core->new_parent) {
parent = core->new_parent;
best_parent_rate = core->new_parent->rate;
else if (core->parent)
} else if (core->parent) {
parent = core->parent;
best_parent_rate = core->parent->rate;
}
if (core->flags & CLK_SET_RATE_UNGATE) {
unsigned long flags;
@ -1500,6 +1512,9 @@ static void clk_change_rate(struct clk_core *core)
__clk_set_parent_after(core, core->new_parent, old_parent);
}
if (core->flags & CLK_OPS_PARENT_ENABLE)
clk_core_prepare_enable(parent);
trace_clk_set_rate(core, core->new_rate);
if (!skip_set_rate && core->ops->set_rate)
@ -1518,6 +1533,9 @@ static void clk_change_rate(struct clk_core *core)
clk_core_unprepare(core);
}
if (core->flags & CLK_OPS_PARENT_ENABLE)
clk_core_disable_unprepare(parent);
if (core->notifier_count && old_rate != core->rate)
__clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);