[PATCH] drivers: soc: qcom: smem: Switch partitions to xarray

[Pranav Mahesh Phansalkar]

From: Tony Truong <tony.truong@xxxxxxxxxxxxxxxx>

The partitions array is currently statically sized and uses the remote
host ID as an index.

Future protocol improvements to allow for more than two hosts in a
partition will require hostIDs to be bitwise significant integers.
This will result in large, sparse host IDs that generally exceed the
current static limit.

Switch to using xarray to efficiently handle these sparse indices and
allow for dynamic growth.

Signed-off-by: Tony Truong <tony.truong@xxxxxxxxxxxxxxxx>
Signed-off-by: Pranav Mahesh Phansalkar <pranav.phansalkar@xxxxxxxxxxxxxxxx>
---
 drivers/soc/qcom/smem.c | 56 ++++++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 26 deletions(-)

diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
index d5c94b47f431..afb21a778fe7 100644
--- a/drivers/soc/qcom/smem.c
+++ b/drivers/soc/qcom/smem.c
@@ -85,9 +85,6 @@
 /* Processor/host identifier for the global partition */
 #define SMEM_GLOBAL_HOST	0xfffe
 
-/* Max number of processors/hosts in a system */
-#define SMEM_HOST_COUNT		25
-
 /**
   * struct smem_proc_comm - proc_comm communication struct (legacy)
   * @command:	current command to be executed
@@ -282,7 +279,7 @@ struct qcom_smem {
 	struct platform_device *socinfo;
 	struct smem_ptable *ptable;
 	struct smem_partition global_partition;
-	struct smem_partition partitions[SMEM_HOST_COUNT];
+	struct xarray partitions;
 
 	unsigned num_regions;
 	struct smem_region regions[] __counted_by(num_regions);
@@ -382,7 +379,7 @@ static struct qcom_smem *__smem = INIT_ERR_PTR(-EPROBE_DEFER);
 int qcom_smem_bust_hwspin_lock_by_host(unsigned int host)
 {
 	/* This function is for remote procs, so ignore SMEM_HOST_APPS */
-	if (host == SMEM_HOST_APPS || host >= SMEM_HOST_COUNT)
+	if (host == SMEM_HOST_APPS || !xa_load(&__smem->partitions, host))
 		return -EINVAL;
 
 	return hwspin_lock_bust(__smem->hwlock, SMEM_HOST_ID_TO_HWSPINLOCK_ID(host));
@@ -530,8 +527,8 @@ int qcom_smem_alloc(unsigned host, unsigned item, size_t size)
 	if (ret)
 		return ret;
 
-	if (host < SMEM_HOST_COUNT && __smem->partitions[host].virt_base) {
-		part = &__smem->partitions[host];
+	part = xa_load(&__smem->partitions, host);
+	if (part) {
 		ret = qcom_smem_alloc_private(__smem, part, item, size);
 	} else if (__smem->global_partition.virt_base) {
 		part = &__smem->global_partition;
@@ -697,8 +694,8 @@ void *qcom_smem_get(unsigned host, unsigned item, size_t *size)
 	if (item >= __smem->item_count)
 		return ERR_PTR(-EINVAL);
 
-	if (host < SMEM_HOST_COUNT && __smem->partitions[host].virt_base) {
-		part = &__smem->partitions[host];
+	part = xa_load(&__smem->partitions, host);
+	if (part) {
 		ptr = qcom_smem_get_private(__smem, part, item, size);
 	} else if (__smem->global_partition.virt_base) {
 		part = &__smem->global_partition;
@@ -730,8 +727,8 @@ int qcom_smem_get_free_space(unsigned host)
 	if (IS_ERR(__smem))
 		return PTR_ERR(__smem);
 
-	if (host < SMEM_HOST_COUNT && __smem->partitions[host].virt_base) {
-		part = &__smem->partitions[host];
+	part = xa_load(&__smem->partitions, host);
+	if (part) {
 		phdr = part->virt_base;
 		ret = le32_to_cpu(phdr->offset_free_cached) -
 		      le32_to_cpu(phdr->offset_free_uncached);
@@ -774,12 +771,11 @@ phys_addr_t qcom_smem_virt_to_phys(void *p)
 {
 	struct smem_partition *part;
 	struct smem_region *area;
+	unsigned long index;
 	u64 offset;
 	u32 i;
 
-	for (i = 0; i < SMEM_HOST_COUNT; i++) {
-		part = &__smem->partitions[i];
-
+	xa_for_each(&__smem->partitions, index, part) {
 		if (addr_in_range(part->virt_base, part->size, p)) {
 			offset = p - part->virt_base;
 
@@ -1016,16 +1012,20 @@ static int
 qcom_smem_enumerate_partitions(struct qcom_smem *smem, u16 local_host)
 {
 	struct smem_partition_header *header;
+	struct smem_partition *part;
 	struct smem_ptable_entry *entry;
 	struct smem_ptable *ptable;
 	u16 remote_host;
 	u16 host0, host1;
+	int ret;
 	int i;
 
 	ptable = qcom_smem_get_ptable(smem);
 	if (IS_ERR(ptable))
 		return PTR_ERR(ptable);
 
+	xa_init(&smem->partitions);
+
 	for (i = 0; i < le32_to_cpu(ptable->num_entries); i++) {
 		entry = &ptable->entry[i];
 		if (!le32_to_cpu(entry->offset))
@@ -1042,12 +1042,7 @@ qcom_smem_enumerate_partitions(struct qcom_smem *smem, u16 local_host)
 		else
 			continue;
 
-		if (remote_host >= SMEM_HOST_COUNT) {
-			dev_err(smem->dev, "bad host %u\n", remote_host);
-			return -EINVAL;
-		}
-
-		if (smem->partitions[remote_host].virt_base) {
+		if (xa_load(&smem->partitions, remote_host)) {
 			dev_err(smem->dev, "duplicate host %u\n", remote_host);
 			return -EINVAL;
 		}
@@ -1056,11 +1051,20 @@ qcom_smem_enumerate_partitions(struct qcom_smem *smem, u16 local_host)
 		if (!header)
 			return -EINVAL;
 
-		smem->partitions[remote_host].virt_base = (void __iomem *)header;
-		smem->partitions[remote_host].phys_base = smem->regions[0].aux_base +
-										le32_to_cpu(entry->offset);
-		smem->partitions[remote_host].size = le32_to_cpu(entry->size);
-		smem->partitions[remote_host].cacheline = le32_to_cpu(entry->cacheline);
+		part = devm_kzalloc(smem->dev, sizeof(struct smem_partition), GFP_KERNEL);
+		if (!part)
+			return -ENOMEM;
+
+		part->virt_base = (void __iomem *)header;
+		part->phys_base = smem->regions[0].aux_base + le32_to_cpu(entry->offset);
+		part->size = le32_to_cpu(entry->size);
+		part->cacheline = le32_to_cpu(entry->cacheline);
+
+		ret = xa_insert(&smem->partitions, remote_host, part, GFP_KERNEL);
+		if (ret) {
+			dev_err(smem->dev, "fail to insert host %u\n", remote_host);
+			return ret;
+		}
 	}
 
 	return 0;
@@ -1229,7 +1233,6 @@ static int qcom_smem_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	BUILD_BUG_ON(SMEM_HOST_APPS >= SMEM_HOST_COUNT);
 	ret = qcom_smem_enumerate_partitions(smem, SMEM_HOST_APPS);
 	if (ret < 0 && ret != -ENOENT)
 		return ret;
@@ -1249,6 +1252,7 @@ static void qcom_smem_remove(struct platform_device *pdev)
 {
 	platform_device_unregister(__smem->socinfo);
 
+	xa_destroy(&__smem->partitions);
 	/* Set to -EPROBE_DEFER to signal unprobed state */
 	__smem = ERR_PTR(-EPROBE_DEFER);
 }

---
base-commit: 7f87a5ea75f011d2c9bc8ac0167e5e2d1adb1594
change-id: 20260409-smem-3204e1ea277a

Best regards,
-- 
Pranav Mahesh Phansalkar <pranav.phansalkar@xxxxxxxxxxxxxxxx>