271 lines
8.3 KiB
Diff
271 lines
8.3 KiB
Diff
From d25cfe9b4f9663216ce4e011e3f1e7fa669ab58a Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Fri, 27 Nov 2015 21:09:05 +0100
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Subject: [PATCH] reset: Add shared reset_control_[de]assert variants
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Add reset_control_deassert_shared / reset_control_assert_shared
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functions which are intended for use by drivers for hw blocks which
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(may) share a reset line with another driver / hw block.
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Unlike the regular reset_control_[de]assert functions these functions
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keep track of how often deassert_shared / assert_shared have been called
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and keep the line deasserted as long as deassert has been called more
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times than assert.
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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---
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Changes in v2:
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-This is a new patch in v2 of this patch-set
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---
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drivers/reset/core.c | 121 ++++++++++++++++++++++++++++++++++++---
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include/linux/reset-controller.h | 2 +
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include/linux/reset.h | 2 +
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3 files changed, 116 insertions(+), 9 deletions(-)
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diff --git a/drivers/reset/core.c b/drivers/reset/core.c
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index 9ab9290..8c3436c 100644
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--- a/drivers/reset/core.c
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+++ b/drivers/reset/core.c
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@@ -22,16 +22,29 @@ static DEFINE_MUTEX(reset_controller_list_mutex);
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static LIST_HEAD(reset_controller_list);
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/**
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+ * struct reset_line - a reset line
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+ * @list: list entry for the reset controllers reset line list
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+ * @id: ID of the reset line in the reset controller device
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+ * @refcnt: Number of reset_control structs referencing this device
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+ * @deassert_cnt: Number of times this reset line has been deasserted
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+ */
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+struct reset_line {
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+ struct list_head list;
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+ unsigned int id;
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+ unsigned int refcnt;
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+ unsigned int deassert_cnt;
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+};
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+
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+/**
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* struct reset_control - a reset control
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* @rcdev: a pointer to the reset controller device
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* this reset control belongs to
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- * @id: ID of the reset controller in the reset
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- * controller device
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+ * @line: reset line for this reset control
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*/
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struct reset_control {
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struct reset_controller_dev *rcdev;
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+ struct reset_line *line;
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struct device *dev;
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- unsigned int id;
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};
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/**
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@@ -66,6 +79,8 @@ int reset_controller_register(struct reset_controller_dev *rcdev)
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rcdev->of_xlate = of_reset_simple_xlate;
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}
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+ INIT_LIST_HEAD(&rcdev->reset_line_head);
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+
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mutex_lock(&reset_controller_list_mutex);
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list_add(&rcdev->list, &reset_controller_list);
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mutex_unlock(&reset_controller_list_mutex);
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@@ -93,7 +108,7 @@ EXPORT_SYMBOL_GPL(reset_controller_unregister);
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int reset_control_reset(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->reset)
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- return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
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+ return rstc->rcdev->ops->reset(rstc->rcdev, rstc->line->id);
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return -ENOTSUPP;
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}
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@@ -106,7 +121,7 @@ EXPORT_SYMBOL_GPL(reset_control_reset);
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int reset_control_assert(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->assert)
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- return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
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+ return rstc->rcdev->ops->assert(rstc->rcdev, rstc->line->id);
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return -ENOTSUPP;
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}
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@@ -119,13 +134,55 @@ EXPORT_SYMBOL_GPL(reset_control_assert);
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int reset_control_deassert(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->deassert)
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- return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
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+ return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->line->id);
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return -ENOTSUPP;
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}
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EXPORT_SYMBOL_GPL(reset_control_deassert);
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/**
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+ * reset_control_assert_shared - asserts a shared reset line
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+ * @rstc: reset controller
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+ *
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+ * Assert a shared reset line, this functions decreases the deassert count
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+ * of the line by one and asserts it if, and only if, the deassert count
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+ * reaches 0.
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+ */
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+int reset_control_assert_shared(struct reset_control *rstc)
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+{
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+ if (!rstc->rcdev->ops->assert)
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+ return -ENOTSUPP;
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+
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+ rstc->line->deassert_cnt--;
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+ if (rstc->line->deassert_cnt)
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+ return 0;
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+
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+ return rstc->rcdev->ops->assert(rstc->rcdev, rstc->line->id);
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+}
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+EXPORT_SYMBOL_GPL(reset_control_assert_shared);
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+
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+/**
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+ * reset_control_deassert_shared - deasserts a shared reset line
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+ * @rstc: reset controller
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+ *
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+ * Assert a shared reset line, this functions increases the deassert count
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+ * of the line by one and deasserts the reset line (if it was not already
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+ * deasserted).
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+ */
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+int reset_control_deassert_shared(struct reset_control *rstc)
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+{
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+ if (!rstc->rcdev->ops->deassert)
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+ return -ENOTSUPP;
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+
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+ rstc->line->deassert_cnt++;
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+ if (rstc->line->deassert_cnt != 1)
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+ return 0;
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+
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+ return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->line->id);
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+}
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+EXPORT_SYMBOL_GPL(reset_control_deassert_shared);
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+
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+/**
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* reset_control_status - returns a negative errno if not supported, a
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* positive value if the reset line is asserted, or zero if the reset
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* line is not asserted.
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@@ -134,12 +191,47 @@ EXPORT_SYMBOL_GPL(reset_control_deassert);
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int reset_control_status(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->status)
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- return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
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+ return rstc->rcdev->ops->status(rstc->rcdev, rstc->line->id);
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return -ENOTSUPP;
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}
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EXPORT_SYMBOL_GPL(reset_control_status);
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+static struct reset_line *reset_line_get(struct reset_controller_dev *rcdev,
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+ unsigned int index)
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+{
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+ struct reset_line *line;
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+
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+ list_for_each_entry(line, &rcdev->reset_line_head, list) {
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+ if (line->id == index) {
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+ line->refcnt++;
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+ return line;
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+ }
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+ }
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+
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+ line = kzalloc(sizeof(*line), GFP_KERNEL);
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+ if (!line)
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+ return NULL;
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+
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+ list_add(&line->list, &rcdev->reset_line_head);
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+ line->id = index;
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+ line->refcnt = 1;
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+
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+ return line;
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+}
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+
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+static void reset_line_put(struct reset_line *line)
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+{
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+ if (!line)
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+ return;
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+
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+ if (--line->refcnt)
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+ return;
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+
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+ list_del(&line->list);
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+ kfree(line);
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+}
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+
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/**
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* of_reset_control_get_by_index - Lookup and obtain a reference to a reset
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* controller by index.
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@@ -155,6 +247,7 @@ struct reset_control *of_reset_control_get_by_index(struct device_node *node,
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{
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struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
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struct reset_controller_dev *r, *rcdev;
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+ struct reset_line *line;
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struct of_phandle_args args;
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int rstc_id;
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int ret;
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@@ -186,16 +279,22 @@ struct reset_control *of_reset_control_get_by_index(struct device_node *node,
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}
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try_module_get(rcdev->owner);
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+
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+ /* reset_controller_list_mutex also protects the reset_line list */
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+ line = reset_line_get(rcdev, rstc_id);
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+
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mutex_unlock(&reset_controller_list_mutex);
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rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
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- if (!rstc) {
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+ if (!line || !rstc) {
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+ kfree(rstc);
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+ reset_line_put(line);
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module_put(rcdev->owner);
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return ERR_PTR(-ENOMEM);
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}
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rstc->rcdev = rcdev;
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- rstc->id = rstc_id;
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+ rstc->line = line;
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return rstc;
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}
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@@ -259,6 +358,10 @@ void reset_control_put(struct reset_control *rstc)
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if (IS_ERR(rstc))
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return;
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+ mutex_lock(&reset_controller_list_mutex);
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+ reset_line_put(rstc->line);
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+ mutex_unlock(&reset_controller_list_mutex);
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+
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module_put(rstc->rcdev->owner);
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kfree(rstc);
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}
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diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h
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index ce6b962..7f2cbd1 100644
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--- a/include/linux/reset-controller.h
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+++ b/include/linux/reset-controller.h
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@@ -31,6 +31,7 @@ struct of_phandle_args;
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* @ops: a pointer to device specific struct reset_control_ops
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* @owner: kernel module of the reset controller driver
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* @list: internal list of reset controller devices
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+ * @reset_line_head: head of internal list of reset lines
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* @of_node: corresponding device tree node as phandle target
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* @of_reset_n_cells: number of cells in reset line specifiers
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* @of_xlate: translation function to translate from specifier as found in the
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@@ -41,6 +42,7 @@ struct reset_controller_dev {
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struct reset_control_ops *ops;
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struct module *owner;
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struct list_head list;
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+ struct list_head reset_line_head;
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struct device_node *of_node;
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int of_reset_n_cells;
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int (*of_xlate)(struct reset_controller_dev *rcdev,
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diff --git a/include/linux/reset.h b/include/linux/reset.h
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index c4c097d..1cca8ce 100644
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--- a/include/linux/reset.h
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+++ b/include/linux/reset.h
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@@ -11,6 +11,8 @@ int reset_control_reset(struct reset_control *rstc);
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int reset_control_assert(struct reset_control *rstc);
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int reset_control_deassert(struct reset_control *rstc);
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int reset_control_status(struct reset_control *rstc);
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+int reset_control_assert_shared(struct reset_control *rstc);
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+int reset_control_deassert_shared(struct reset_control *rstc);
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struct reset_control *reset_control_get(struct device *dev, const char *id);
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void reset_control_put(struct reset_control *rstc);
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