gpiolib: cdev: relocate debounce_period_us from struct gpio_desc
Store the debounce period for a requested line locally, rather than in the debounce_period_us field in the gpiolib struct gpio_desc. Add a global tree of lines containing supplemental line information to make the debounce period available to be reported by the GPIO_V2_GET_LINEINFO_IOCTL and the line change notifier. Signed-off-by: Kent Gibson <warthog618@gmail.com> Reviewed-by: Andy Shevchenko <andy@kernel.org> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Kent Gibson
Bartosz Golaszewski
parent
40aa7e290b
commit
9344e34e79
@ -5,6 +5,7 @@
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#include <linux/bitmap.h>
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#include <linux/build_bug.h>
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#include <linux/cdev.h>
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#include <linux/cleanup.h>
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#include <linux/compat.h>
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#include <linux/compiler.h>
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#include <linux/device.h>
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@ -21,6 +22,7 @@
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#include <linux/mutex.h>
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#include <linux/pinctrl/consumer.h>
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#include <linux/poll.h>
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#include <linux/rbtree.h>
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#include <linux/seq_file.h>
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#include <linux/spinlock.h>
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#include <linux/timekeeping.h>
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@ -461,6 +463,7 @@ out_free_lh:
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/**
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* struct line - contains the state of a requested line
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* @node: to store the object in supinfo_tree if supplemental
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* @desc: the GPIO descriptor for this line.
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* @req: the corresponding line request
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* @irq: the interrupt triggered in response to events on this GPIO
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@ -473,6 +476,7 @@ out_free_lh:
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* @line_seqno: the seqno for the current edge event in the sequence of
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* events for this line.
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* @work: the worker that implements software debouncing
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* @debounce_period_us: the debounce period in microseconds
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* @sw_debounced: flag indicating if the software debouncer is active
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* @level: the current debounced physical level of the line
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* @hdesc: the Hardware Timestamp Engine (HTE) descriptor
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@ -481,6 +485,7 @@ out_free_lh:
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* @last_seqno: the last sequence number before debounce period expires
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*/
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struct line {
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struct rb_node node;
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struct gpio_desc *desc;
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/*
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* -- edge detector specific fields --
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@ -514,6 +519,15 @@ struct line {
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* -- debouncer specific fields --
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*/
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struct delayed_work work;
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/*
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* debounce_period_us is accessed by debounce_irq_handler() and
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* process_hw_ts() which are disabled when modified by
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* debounce_setup(), edge_detector_setup() or edge_detector_stop()
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* or can live with a stale version when updated by
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* edge_detector_update().
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* The modifying functions are themselves mutually exclusive.
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*/
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unsigned int debounce_period_us;
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/*
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* sw_debounce is accessed by linereq_set_config(), which is the
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* only setter, and linereq_get_values(), which can live with a
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@ -546,6 +560,17 @@ struct line {
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#endif /* CONFIG_HTE */
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};
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/*
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* a rbtree of the struct lines containing supplemental info.
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* Used to populate gpio_v2_line_info with cdev specific fields not contained
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* in the struct gpio_desc.
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* A line is determined to contain supplemental information by
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* line_has_supinfo().
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*/
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static struct rb_root supinfo_tree = RB_ROOT;
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/* covers supinfo_tree */
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static DEFINE_SPINLOCK(supinfo_lock);
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/**
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* struct linereq - contains the state of a userspace line request
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* @gdev: the GPIO device the line request pertains to
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@ -559,7 +584,8 @@ struct line {
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* this line request. Note that this is not used when @num_lines is 1, as
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* the line_seqno is then the same and is cheaper to calculate.
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* @config_mutex: mutex for serializing ioctl() calls to ensure consistency
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* of configuration, particularly multi-step accesses to desc flags.
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* of configuration, particularly multi-step accesses to desc flags and
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* changes to supinfo status.
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* @lines: the lines held by this line request, with @num_lines elements.
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*/
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struct linereq {
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@ -575,6 +601,103 @@ struct linereq {
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struct line lines[] __counted_by(num_lines);
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};
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static void supinfo_insert(struct line *line)
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{
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struct rb_node **new = &(supinfo_tree.rb_node), *parent = NULL;
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struct line *entry;
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guard(spinlock)(&supinfo_lock);
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while (*new) {
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entry = container_of(*new, struct line, node);
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parent = *new;
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if (line->desc < entry->desc) {
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new = &((*new)->rb_left);
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} else if (line->desc > entry->desc) {
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new = &((*new)->rb_right);
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} else {
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/* this should never happen */
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WARN(1, "duplicate line inserted");
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return;
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}
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}
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rb_link_node(&line->node, parent, new);
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rb_insert_color(&line->node, &supinfo_tree);
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}
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static void supinfo_erase(struct line *line)
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{
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guard(spinlock)(&supinfo_lock);
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rb_erase(&line->node, &supinfo_tree);
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}
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static struct line *supinfo_find(struct gpio_desc *desc)
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{
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struct rb_node *node = supinfo_tree.rb_node;
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struct line *line;
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while (node) {
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line = container_of(node, struct line, node);
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if (desc < line->desc)
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node = node->rb_left;
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else if (desc > line->desc)
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node = node->rb_right;
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else
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return line;
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}
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return NULL;
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}
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static void supinfo_to_lineinfo(struct gpio_desc *desc,
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struct gpio_v2_line_info *info)
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{
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struct gpio_v2_line_attribute *attr;
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struct line *line;
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guard(spinlock)(&supinfo_lock);
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line = supinfo_find(desc);
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if (!line)
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return;
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attr = &info->attrs[info->num_attrs];
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attr->id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
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attr->debounce_period_us = READ_ONCE(line->debounce_period_us);
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info->num_attrs++;
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}
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static inline bool line_has_supinfo(struct line *line)
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{
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return READ_ONCE(line->debounce_period_us);
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}
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/*
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* Checks line_has_supinfo() before and after the change to avoid unnecessary
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* supinfo_tree access.
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* Called indirectly by linereq_create() or linereq_set_config() so line
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* is already protected from concurrent changes.
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*/
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static void line_set_debounce_period(struct line *line,
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unsigned int debounce_period_us)
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{
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bool was_suppl = line_has_supinfo(line);
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WRITE_ONCE(line->debounce_period_us, debounce_period_us);
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/* if supinfo status is unchanged then we're done */
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if (line_has_supinfo(line) == was_suppl)
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return;
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/* supinfo status has changed, so update the tree */
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if (was_suppl)
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supinfo_erase(line);
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else
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supinfo_insert(line);
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}
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#define GPIO_V2_LINE_BIAS_FLAGS \
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(GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
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GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
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@ -723,7 +846,7 @@ static enum hte_return process_hw_ts(struct hte_ts_data *ts, void *p)
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line->total_discard_seq++;
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line->last_seqno = ts->seq;
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mod_delayed_work(system_wq, &line->work,
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usecs_to_jiffies(READ_ONCE(line->desc->debounce_period_us)));
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usecs_to_jiffies(READ_ONCE(line->debounce_period_us)));
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} else {
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if (unlikely(ts->seq < line->line_seqno))
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return HTE_CB_HANDLED;
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@ -864,7 +987,7 @@ static irqreturn_t debounce_irq_handler(int irq, void *p)
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struct line *line = p;
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mod_delayed_work(system_wq, &line->work,
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usecs_to_jiffies(READ_ONCE(line->desc->debounce_period_us)));
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usecs_to_jiffies(READ_ONCE(line->debounce_period_us)));
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return IRQ_HANDLED;
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}
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@ -946,7 +1069,7 @@ static int debounce_setup(struct line *line, unsigned int debounce_period_us)
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/* try hardware */
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ret = gpiod_set_debounce(line->desc, debounce_period_us);
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if (!ret) {
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WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us);
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line_set_debounce_period(line, debounce_period_us);
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return ret;
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}
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if (ret != -ENOTSUPP)
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@ -1025,8 +1148,7 @@ static void edge_detector_stop(struct line *line)
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cancel_delayed_work_sync(&line->work);
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WRITE_ONCE(line->sw_debounced, 0);
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WRITE_ONCE(line->edflags, 0);
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if (line->desc)
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WRITE_ONCE(line->desc->debounce_period_us, 0);
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line_set_debounce_period(line, 0);
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/* do not change line->level - see comment in debounced_value() */
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}
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@ -1051,7 +1173,7 @@ static int edge_detector_setup(struct line *line,
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ret = debounce_setup(line, debounce_period_us);
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if (ret)
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return ret;
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WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us);
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line_set_debounce_period(line, debounce_period_us);
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}
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/* detection disabled or sw debouncer will provide edge detection */
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@ -1093,12 +1215,12 @@ static int edge_detector_update(struct line *line,
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gpio_v2_line_config_debounce_period(lc, line_idx);
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if ((active_edflags == edflags) &&
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(READ_ONCE(line->desc->debounce_period_us) == debounce_period_us))
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(READ_ONCE(line->debounce_period_us) == debounce_period_us))
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return 0;
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/* sw debounced and still will be...*/
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if (debounce_period_us && READ_ONCE(line->sw_debounced)) {
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WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us);
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line_set_debounce_period(line, debounce_period_us);
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return 0;
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}
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@ -1573,6 +1695,7 @@ static ssize_t linereq_read(struct file *file, char __user *buf,
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static void linereq_free(struct linereq *lr)
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{
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struct line *line;
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unsigned int i;
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if (lr->device_unregistered_nb.notifier_call)
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@ -1580,10 +1703,14 @@ static void linereq_free(struct linereq *lr)
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&lr->device_unregistered_nb);
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for (i = 0; i < lr->num_lines; i++) {
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if (lr->lines[i].desc) {
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edge_detector_stop(&lr->lines[i]);
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gpiod_free(lr->lines[i].desc);
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}
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line = &lr->lines[i];
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if (!line->desc)
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continue;
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edge_detector_stop(line);
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if (line_has_supinfo(line))
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supinfo_erase(line);
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gpiod_free(line->desc);
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}
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kfifo_free(&lr->events);
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kfree(lr->label);
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@ -2274,8 +2401,6 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
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struct gpio_chip *gc = desc->gdev->chip;
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bool ok_for_pinctrl;
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unsigned long flags;
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u32 debounce_period_us;
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unsigned int num_attrs = 0;
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memset(info, 0, sizeof(*info));
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info->offset = gpio_chip_hwgpio(desc);
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@ -2341,14 +2466,6 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
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else if (test_bit(FLAG_EVENT_CLOCK_HTE, &desc->flags))
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info->flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE;
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debounce_period_us = READ_ONCE(desc->debounce_period_us);
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if (debounce_period_us) {
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info->attrs[num_attrs].id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
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info->attrs[num_attrs].debounce_period_us = debounce_period_us;
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num_attrs++;
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}
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info->num_attrs = num_attrs;
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spin_unlock_irqrestore(&gpio_lock, flags);
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}
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@ -2455,6 +2572,7 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
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return -EBUSY;
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}
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gpio_desc_to_lineinfo(desc, &lineinfo);
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supinfo_to_lineinfo(desc, &lineinfo);
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if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
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if (watch)
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@ -2545,6 +2663,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
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chg.event_type = action;
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chg.timestamp_ns = ktime_get_ns();
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gpio_desc_to_lineinfo(desc, &chg.info);
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supinfo_to_lineinfo(desc, &chg.info);
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ret = kfifo_in_spinlocked(&cdev->events, &chg, 1, &cdev->wait.lock);
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if (ret)
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