[PATCH v4 1/5] gnss: sirf: write data to gnss only when the gnss device is open

[Andreas Kemnade]

The api forbids writing data there otherwise. Prepare for the
serdev_open()/close() being a part of sirf_set_active.

Signed-off-by: Andreas Kemnade <andr...@kemnade.info>
---
No changes in v4
Changes in v3:
 - add more locking
 - style cleanup 
 - mutex *not* renamed since we need a second one

Changes in v2:
 - add locking

 drivers/gnss/sirf.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/gnss/sirf.c b/drivers/gnss/sirf.c
index 59cde7e923b8..49bc021325e9 100644
--- a/drivers/gnss/sirf.c
+++ b/drivers/gnss/sirf.c
@@ -35,6 +35,10 @@ struct sirf_data {
        struct gpio_desc *wakeup;
        int irq;
        bool active;
+
+       struct mutex gdev_mutex;
+       bool open;
+
        wait_queue_head_t power_wait;
 };
 
@@ -44,9 +48,18 @@ static int sirf_open(struct gnss_device *gdev)
        struct serdev_device *serdev = data->serdev;
        int ret;
 
+       mutex_lock(&data->gdev_mutex);
+       data->open = true;
+       mutex_unlock(&data->gdev_mutex);
+
        ret = serdev_device_open(serdev);
-       if (ret)
+       if (ret) {
+               mutex_lock(&data->gdev_mutex);
+               data->open = false;
+               mutex_unlock(&data->gdev_mutex);
                return ret;
+       }
+
 
        serdev_device_set_baudrate(serdev, data->speed);
        serdev_device_set_flow_control(serdev, false);
@@ -63,6 +76,10 @@ static int sirf_open(struct gnss_device *gdev)
 err_close:
        serdev_device_close(serdev);
 
+       mutex_lock(&data->gdev_mutex);
+       data->open = false;
+       mutex_unlock(&data->gdev_mutex);
+
        return ret;
 }
 
@@ -74,6 +91,10 @@ static void sirf_close(struct gnss_device *gdev)
        serdev_device_close(serdev);
 
        pm_runtime_put(&serdev->dev);
+
+       mutex_lock(&data->gdev_mutex);
+       data->open = false;
+       mutex_unlock(&data->gdev_mutex);
 }
 
 static int sirf_write_raw(struct gnss_device *gdev, const unsigned char *buf,
@@ -105,8 +126,14 @@ static int sirf_receive_buf(struct serdev_device *serdev,
 {
        struct sirf_data *data = serdev_device_get_drvdata(serdev);
        struct gnss_device *gdev = data->gdev;
+       int ret = 0;
 
-       return gnss_insert_raw(gdev, buf, count);
+       mutex_lock(&data->gdev_mutex);
+       if (data->open)
+               ret = gnss_insert_raw(gdev, buf, count);
+       mutex_unlock(&data->gdev_mutex);
+
+       return ret;
 }
 
 static const struct serdev_device_ops sirf_serdev_ops = {
@@ -275,6 +302,7 @@ static int sirf_probe(struct serdev_device *serdev)
        data->serdev = serdev;
        data->gdev = gdev;
 
+       mutex_init(&data->gdev_mutex);
        init_waitqueue_head(&data->power_wait);
 
        serdev_device_set_drvdata(serdev, data);
-- 
2.11.0