[PATCH] soc: qcom: llcc: Add llcc device availability check

[Mukesh Ojha]

When llcc driver is enabled  and llcc device is not
physically there on the SoC, client can get
-EPROBE_DEFER on calling llcc_slice_getd() and it
is possible they defer forever.

Let's add a check device availabilty and set the
appropriate applicable error in drv_data.

Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
---
 drivers/soc/qcom/llcc-qcom.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
index 4ca88eaebf06..cb336b183bba 100644
--- a/drivers/soc/qcom/llcc-qcom.c
+++ b/drivers/soc/qcom/llcc-qcom.c
@@ -769,6 +769,27 @@ static const struct qcom_sct_config x1e80100_cfgs = {
 };
 
 static struct llcc_drv_data *drv_data = (void *) -EPROBE_DEFER;
+static DEFINE_MUTEX(dev_avail);
+
+static bool is_llcc_device_available(void)
+{
+	static struct llcc_drv_data *ptr;
+
+	mutex_lock(&dev_avail);
+	if (!ptr) {
+		struct device_node *node;
+
+		node = of_find_node_by_name(NULL, "system-cache-controller");
+		if (!of_device_is_available(node)) {
+			pr_warn("llcc-qcom: system-cache-controller node not found\n");
+			drv_data = ERR_PTR(-ENODEV);
+		}
+		of_node_put(node);
+		ptr = drv_data;
+	}
+	mutex_unlock(&dev_avail);
+	return (PTR_ERR(ptr) != -ENODEV) ? true : false;
+}
 
 /**
  * llcc_slice_getd - get llcc slice descriptor
@@ -783,7 +804,7 @@ struct llcc_slice_desc *llcc_slice_getd(u32 uid)
 	struct llcc_slice_desc *desc;
 	u32 sz, count;
 
-	if (IS_ERR(drv_data))
+	if (!is_llcc_device_available() || IS_ERR(drv_data))
 		return ERR_CAST(drv_data);
 
 	cfg = drv_data->cfg;
-- 
2.43.0.254.ga26002b62827