soc: qcom: smem: introduce qcom_smem_get_soc_id()

Introduce a helper to return the SoC SMEM ID, which is used to identify the
exact SoC model as there may be differences in the same SoC family.

Currently, cpufreq-nvmem does this completely in the driver and there has
been more interest expresed for other drivers to use this information so
lets expose a common helper to prevent redoing it in individual drivers
since this field is present on every SMEM table version.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230526204802.3081168-3-robimarko@gmail.com

drivers/soc/qcom/smem.c

@@ -14,6 +14,7 @@
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/soc/qcom/smem.h>
+#include <linux/soc/qcom/socinfo.h>
 
 /*
  * The Qualcomm shared memory system is a allocate only heap structure that
@@ -772,6 +773,28 @@ phys_addr_t qcom_smem_virt_to_phys(void *p)
 }
 EXPORT_SYMBOL_GPL(qcom_smem_virt_to_phys);
 
+/**
+ * qcom_smem_get_soc_id() - return the SoC ID
+ * @id:	On success, we return the SoC ID here.
+ *
+ * Look up SoC ID from HW/SW build ID and return it.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int qcom_smem_get_soc_id(u32 *id)
+{
+	struct socinfo *info;
+
+	info = qcom_smem_get(QCOM_SMEM_HOST_ANY, SMEM_HW_SW_BUILD_ID, NULL);
+	if (IS_ERR(info))
+		return PTR_ERR(info);
+
+	*id = __le32_to_cpu(info->id);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(qcom_smem_get_soc_id);
+
 static int qcom_smem_get_sbl_version(struct qcom_smem *smem)
 {
 	struct smem_header *header;

include/linux/soc/qcom/smem.h

@@ -11,4 +11,6 @@ int qcom_smem_get_free_space(unsigned host);
 
 phys_addr_t qcom_smem_virt_to_phys(void *p);
 
+int qcom_smem_get_soc_id(u32 *id);
+
 #endif