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authorPhilipp Zabel <p.zabel@pengutronix.de>2017-07-12 17:51:22 +0200
committerPhilipp Zabel <p.zabel@pengutronix.de>2017-07-19 12:10:48 +0200
commit21240eb94f1f6df30aa88f7e7b754ed46024d666 (patch)
treeb81abf9a23450b19e795c5916c880643b8b397cb /drivers/reset
parent17c82e206d2a3cd876b64921c59116f1ecdce6ad (diff)
reset: make (de)assert report success for self-deasserting reset drivers
By now there are drivers using shared reset controls and (de)assert calls on platforms with self-deasserting reset lines and thus reset drivers that do not implement .assert() and .deassert(). As long as the initial state of the reset line is deasserted, there is no reason for a reset_control_assert call to return an error for shared reset controls, or for a reset_control_deassert call to return an error for either shared or exclusive reset controls: after a call to reset_control_deassert the reset line is guaranteed to be deasserted, and after a call to reset_control_assert it is valid for the reset line to stay deasserted for shared reset controls. Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/reset')
-rw-r--r--drivers/reset/core.c31
1 files changed, 25 insertions, 6 deletions
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index c8fb4426b218..1d21c6f7d56c 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -280,9 +280,6 @@ int reset_control_assert(struct reset_control *rstc)
if (reset_control_is_array(rstc))
return reset_control_array_assert(rstc_to_array(rstc));
- if (!rstc->rcdev->ops->assert)
- return -ENOTSUPP;
-
if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
return -EINVAL;
@@ -292,6 +289,21 @@ int reset_control_assert(struct reset_control *rstc)
if (atomic_dec_return(&rstc->deassert_count) != 0)
return 0;
+
+ /*
+ * Shared reset controls allow the reset line to be in any state
+ * after this call, so doing nothing is a valid option.
+ */
+ if (!rstc->rcdev->ops->assert)
+ return 0;
+ } else {
+ /*
+ * If the reset controller does not implement .assert(), there
+ * is no way to guarantee that the reset line is asserted after
+ * this call.
+ */
+ if (!rstc->rcdev->ops->assert)
+ return -ENOTSUPP;
}
return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
@@ -321,9 +333,6 @@ int reset_control_deassert(struct reset_control *rstc)
if (reset_control_is_array(rstc))
return reset_control_array_deassert(rstc_to_array(rstc));
- if (!rstc->rcdev->ops->deassert)
- return -ENOTSUPP;
-
if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
return -EINVAL;
@@ -332,6 +341,16 @@ int reset_control_deassert(struct reset_control *rstc)
return 0;
}
+ /*
+ * If the reset controller does not implement .deassert(), we assume
+ * that it handles self-deasserting reset lines via .reset(). In that
+ * case, the reset lines are deasserted by default. If that is not the
+ * case, the reset controller driver should implement .deassert() and
+ * return -ENOTSUPP.
+ */
+ if (!rstc->rcdev->ops->deassert)
+ return 0;
+
return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
}
EXPORT_SYMBOL_GPL(reset_control_deassert);

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