[PATCH v2 1/3] clk: ti: add a usecount for autoidle

Andreas Kemnade
2018-11-10T20:31:55Z

Multiple users might deny autoidle on a clock. So we should have some
counting here, also according to the comment in _setup_iclk_autoidle().
Also setting autoidle regs is not atomic, so there is another reason
for locking.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
---
Changes since v1:
- use spinlocks instead of mutexes
- invert logic
---
drivers/clk/ti/autoidle.c | 36 ++++++++++++++++++++++++++++--------
include/linux/clk/ti.h | 1 +
2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/ti/autoidle.c b/drivers/clk/ti/autoidle.c
index 7bb9afbe4058..161f67850393 100644
--- a/drivers/clk/ti/autoidle.c
+++ b/drivers/clk/ti/autoidle.c
@@ -37,6 +37,14 @@ struct clk_ti_autoidle {
static LIST_HEAD(autoidle_clks);
static LIST_HEAD(clk_hw_omap_clocks);

+/*
+ * we have some non-atomic read/write
+ * operations behind it, so lets
+ * take one lock for handling autoidle
+ * of all clocks
+ */
+static DEFINE_SPINLOCK(autoidle_spinlock);
+
/**
* omap2_clk_deny_idle - disable autoidle on an OMAP clock
* @clk: struct clk * to disable autoidle for
@@ -48,8 +56,15 @@ int omap2_clk_deny_idle(struct clk *clk)
struct clk_hw_omap *c;

c = to_clk_hw_omap(__clk_get_hw(clk));
- if (c->ops && c->ops->deny_idle)
- c->ops->deny_idle(c);
+ if (c->ops && c->ops->deny_idle) {
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&autoidle_spinlock, irqflags);
+ c->autoidle_count++;
+ if (c->autoidle_count == 1)
+ c->ops->deny_idle(c);
+ spin_unlock_irqrestore(&autoidle_spinlock, irqflags);
+ }
return 0;
}

@@ -64,8 +79,15 @@ int omap2_clk_allow_idle(struct clk *clk)
struct clk_hw_omap *c;

c = to_clk_hw_omap(__clk_get_hw(clk));
- if (c->ops && c->ops->allow_idle)
- c->ops->allow_idle(c);
+ if (c->ops && c->ops->allow_idle) {
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&autoidle_spinlock, irqflags);
+ c->autoidle_count--;
+ if (c->autoidle_count == 0)
+ c->ops->allow_idle(c);
+ spin_unlock_irqrestore(&autoidle_spinlock, irqflags);
+ }
return 0;
}

@@ -201,8 +223,7 @@ int omap2_clk_enable_autoidle_all(void)
struct clk_hw_omap *c;

list_for_each_entry(c, &clk_hw_omap_clocks, node)
- if (c->ops && c->ops->allow_idle)
- c->ops->allow_idle(c);
+ omap2_clk_allow_idle(c->hw.clk);

_clk_generic_allow_autoidle_all();

@@ -223,8 +244,7 @@ int omap2_clk_disable_autoidle_all(void)
struct clk_hw_omap *c;

list_for_each_entry(c, &clk_hw_omap_clocks, node)
- if (c->ops && c->ops->deny_idle)
- c->ops->deny_idle(c);
+ omap2_clk_deny_idle(c->hw.clk);

_clk_generic_deny_autoidle_all();

diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
index eacc5df57b99..78872efc7be0 100644
--- a/include/linux/clk/ti.h
+++ b/include/linux/clk/ti.h
@@ -160,6 +160,7 @@ struct clk_hw_omap {
struct clockdomain *clkdm;
const struct clk_hw_omap_ops *ops;
u32 context;
+ int autoidle_count;
};

/*
--
2.11.0