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Subject[PATCH v3 08/18] gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL
Date
Add support for GPIO_V2_LINE_SET_CONFIG_IOCTL, the uAPI v2
line set config ioctl.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
drivers/gpio/gpiolib-cdev.c | 92 +++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index c1b916224240..d34dad50a048 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -16,6 +16,7 @@
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/pinctrl/consumer.h>
#include <linux/poll.h>
#include <linux/spinlock.h>
@@ -418,6 +419,8 @@ struct edge_detector {
* @seqno: the sequence number for edge events generated on all lines in
* this line request. Note that this is not used when @num_descs 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.
* @edets: an array of edge detectors, of size @num_descs
* @descs: the GPIO descriptors held by this line request, with @num_descs
* elements.
@@ -429,6 +432,7 @@ struct line {
wait_queue_head_t wait;
DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
atomic_t seqno;
+ struct mutex config_mutex;
struct edge_detector *edets;
struct gpio_desc *descs[];
};
@@ -703,6 +707,30 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
return 0;
}

+static int gpio_v2_line_config_change_validate(struct line *line,
+ struct gpio_v2_line_config *lc)
+{
+ int i;
+ u64 flags;
+ struct gpio_desc *desc;
+
+ for (i = 0; i < line->num_descs; i++) {
+ desc = line->descs[i];
+ flags = gpio_v2_line_config_flags(lc, i);
+ /* disallow edge detection changes */
+ if (line->edets[i].flags != (flags & GPIO_V2_LINE_EDGE_FLAGS))
+ return -EINVAL;
+
+ if (line->edets[i].flags) {
+ /* disallow polarity changes */
+ if (test_bit(FLAG_ACTIVE_LOW, &desc->flags) !=
+ ((flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW) != 0))
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
unsigned long *flagsp)
{
@@ -783,6 +811,67 @@ static long line_get_values(struct line *line, void __user *ip)
return 0;
}

+static long line_set_config_locked(struct line *line,
+ struct gpio_v2_line_config *lc)
+{
+ struct gpio_desc *desc;
+ int i, ret;
+ u64 flags;
+
+ ret = gpio_v2_line_config_change_validate(line, lc);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < line->num_descs; i++) {
+ desc = line->descs[i];
+ flags = gpio_v2_line_config_flags(lc, i);
+
+ gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
+ /*
+ * Lines have to be requested explicitly for input
+ * or output, else the line will be treated "as is".
+ */
+ if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
+ int val = gpio_v2_line_config_output_value(lc, i);
+
+ edge_detector_stop(&line->edets[i]);
+ ret = gpiod_direction_output(desc, val);
+ if (ret)
+ return ret;
+ } else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
+ ret = gpiod_direction_input(desc);
+ if (ret)
+ return ret;
+ }
+
+ blocking_notifier_call_chain(&desc->gdev->notifier,
+ GPIO_V2_LINE_CHANGED_CONFIG,
+ desc);
+ }
+ return 0;
+}
+
+static long line_set_config(struct line *line, void __user *ip)
+{
+ struct gpio_v2_line_config lc;
+ int ret;
+
+ if (copy_from_user(&lc, ip, sizeof(lc)))
+ return -EFAULT;
+
+ ret = gpio_v2_line_config_validate(&lc, line->num_descs);
+ if (ret)
+ return ret;
+
+ mutex_lock(&line->config_mutex);
+
+ ret = line_set_config_locked(line, &lc);
+
+ mutex_unlock(&line->config_mutex);
+
+ return ret;
+}
+
static long line_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
@@ -791,6 +880,8 @@ static long line_ioctl(struct file *file, unsigned int cmd,

if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
return line_get_values(line, ip);
+ else if (cmd == GPIO_V2_LINE_SET_CONFIG_IOCTL)
+ return line_set_config(line, ip);

return -EINVAL;
}
@@ -964,6 +1055,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
}
}

+ mutex_init(&line->config_mutex);
init_waitqueue_head(&line->wait);
if (has_edge_detection) {
size = lr.event_buffer_size;
--
2.28.0
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