soc: qcom: smem: better track SMEM uninitialized state

There is currently a problem where, in the specific case of SMEM not
initialized by SBL, any SMEM API wrongly returns PROBE_DEFER
communicating wrong info to any user of this API.

A better way to handle this would be to track the SMEM state and return
a different kind of error than PROBE_DEFER.

Rework the __smem handle to always init it to the error pointer
-EPROBE_DEFER following what is already done by the SMEM API.
If we detect that the SBL didn't initialized SMEM, set the __smem handle
to the error pointer -ENODEV.
Also rework the SMEM API to handle the __smem handle to be an error
pointer and return it appropriately.

This way user of the API can react and return a proper error or use
fallback way for the failing API.

While at it, change the return error when SMEM is not initialized by SBL
also to -ENODEV to make it consistent with the __smem handle and use
dev_err_probe() helper to return the message.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Link: https://lore.kernel.org/r/20251031130835.7953-3-ansuelsmth@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
index f1d1b5aa5e4db6e1f3befa84f387ad060ffb8366..f4a4acfefba9a5aa7c49303c5ced5b5dfb467177 100644 (file)
--- a/drivers/soc/qcom/smem.c
+++ b/drivers/soc/qcom/smem.c
@@ -353,8 +353,12 @@ static void *cached_entry_to_item(struct smem_private_entry *e)
        return p - le32_to_cpu(e->size);
 }
 
-/* Pointer to the one and only smem handle */
-static struct qcom_smem *__smem;
+/*
+ * Pointer to the one and only smem handle.
+ * Init to -EPROBE_DEFER to signal SMEM still has to be probed.
+ * Can be set to -ENODEV if SMEM is not initialized by SBL.
+ */
+static struct qcom_smem *__smem = INIT_ERR_PTR(-EPROBE_DEFER);
 
 /* Timeout (ms) for the trylock of remote spinlocks */
 #define HWSPINLOCK_TIMEOUT     1000
@@ -508,8 +512,8 @@ int qcom_smem_alloc(unsigned host, unsigned item, size_t size)
        unsigned long flags;
        int ret;
 
-       if (!__smem)
-               return -EPROBE_DEFER;
+       if (IS_ERR(__smem))
+               return PTR_ERR(__smem);
 
        if (item < SMEM_ITEM_LAST_FIXED) {
                dev_err(__smem->dev,
@@ -685,10 +689,10 @@ invalid_canary:
 void *qcom_smem_get(unsigned host, unsigned item, size_t *size)
 {
        struct smem_partition *part;
-       void *ptr = ERR_PTR(-EPROBE_DEFER);
+       void *ptr;
 
-       if (!__smem)
-               return ptr;
+       if (IS_ERR(__smem))
+               return __smem;
 
        if (WARN_ON(item >= __smem->item_count))
                return ERR_PTR(-EINVAL);
@@ -723,8 +727,8 @@ int qcom_smem_get_free_space(unsigned host)
        struct smem_header *header;
        unsigned ret;
 
-       if (!__smem)
-               return -EPROBE_DEFER;
+       if (IS_ERR(__smem))
+               return PTR_ERR(__smem);
 
        if (host < SMEM_HOST_COUNT && __smem->partitions[host].virt_base) {
                part = &__smem->partitions[host];
@@ -1181,8 +1185,8 @@ static int qcom_smem_probe(struct platform_device *pdev)
        header = smem->regions[0].virt_base;
        if (le32_to_cpu(header->initialized) != 1 ||
            le32_to_cpu(header->reserved)) {
-               dev_err(&pdev->dev, "SMEM is not initialized by SBL\n");
-               return -EINVAL;
+               __smem = ERR_PTR(-ENODEV);
+               return dev_err_probe(&pdev->dev, PTR_ERR(__smem), "SMEM is not initialized by SBL\n");
        }
 
        hwlock_id = of_hwspin_lock_get_id(pdev->dev.of_node, 0);