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Subject[PATCH v8 10/20] 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 | 88 +++++++++++++++++++++++++++++++++++++
1 file changed, 88 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 7161c8921298..b6da92d9dba1 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>
@@ -424,6 +425,8 @@ struct line {
* @seqno: the sequence number for edge events generated on all lines in
* 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.
* @lines: the lines held by this line request, with @num_lines elements.
*/
struct linereq {
@@ -434,6 +437,7 @@ struct linereq {
u32 event_buffer_size;
DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
atomic_t seqno;
+ struct mutex config_mutex;
struct line lines[];
};

@@ -541,6 +545,8 @@ static void edge_detector_stop(struct line *line)
free_irq(line->irq, line);
line->irq = 0;
}
+
+ line->eflags = 0;
}

static int edge_detector_setup(struct line *line,
@@ -582,6 +588,17 @@ static int edge_detector_setup(struct line *line,
return 0;
}

+static int edge_detector_update(struct line *line, u64 eflags,
+ bool polarity_change)
+{
+ if ((line->eflags == eflags) && !polarity_change)
+ return 0;
+
+ edge_detector_stop(line);
+
+ return edge_detector_setup(line, eflags);
+}
+
static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
unsigned int line_idx)
{
@@ -762,6 +779,74 @@ static long linereq_get_values(struct linereq *lr, void __user *ip)
return 0;
}

+static long linereq_set_config_unlocked(struct linereq *lr,
+ struct gpio_v2_line_config *lc)
+{
+ struct gpio_desc *desc;
+ unsigned int i;
+ u64 flags;
+ bool polarity_change;
+ int ret;
+
+ for (i = 0; i < lr->num_lines; i++) {
+ desc = lr->lines[i].desc;
+ flags = gpio_v2_line_config_flags(lc, i);
+ polarity_change =
+ (test_bit(FLAG_ACTIVE_LOW, &desc->flags) !=
+ ((flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW) != 0));
+
+ 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(&lr->lines[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;
+
+ ret = edge_detector_update(&lr->lines[i],
+ flags & GPIO_V2_LINE_EDGE_FLAGS,
+ polarity_change);
+ if (ret)
+ return ret;
+ }
+
+ blocking_notifier_call_chain(&desc->gdev->notifier,
+ GPIO_V2_LINE_CHANGED_CONFIG,
+ desc);
+ }
+ return 0;
+}
+
+static long linereq_set_config(struct linereq *lr, 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, lr->num_lines);
+ if (ret)
+ return ret;
+
+ mutex_lock(&lr->config_mutex);
+
+ ret = linereq_set_config_unlocked(lr, &lc);
+
+ mutex_unlock(&lr->config_mutex);
+
+ return ret;
+}
+
static long linereq_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
@@ -770,6 +855,8 @@ static long linereq_ioctl(struct file *file, unsigned int cmd,

if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
return linereq_get_values(lr, ip);
+ else if (cmd == GPIO_V2_LINE_SET_CONFIG_IOCTL)
+ return linereq_set_config(lr, ip);

return -EINVAL;
}
@@ -930,6 +1017,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
}
}

+ mutex_init(&lr->config_mutex);
init_waitqueue_head(&lr->wait);
lr->event_buffer_size = ulr.event_buffer_size;
if (lr->event_buffer_size == 0)
--
2.28.0
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