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gpiolib: cdev: relocate debounce_period_us from struct gpio_desc

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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 2023-12-19 08:41:54 +08:00 committed by Bartosz Golaszewski
parent 40aa7e290b
commit 9344e34e79
1 changed files with 142 additions and 23 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

165
drivers/gpio/gpiolib-cdev.c
View file

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