firmware: qcom: scm: smc: switch to using the SCM allocator

We need to allocate, map and pass a buffer to the trustzone if we have
more than 4 arguments for a given SCM call. Let's use the new TrustZone
allocator for that memory and shrink the code in process.

As this code lives in a different compilation unit than the rest of the
SCM code, we need to provide a helper in the form of
qcom_scm_get_tzmem_pool() that allows the SMC low-level routines to
access the SCM memory pool.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
Tested-by: Deepti Jaggi <quic_djaggi@quicinc.com> #sa8775p-ride
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Link: https://lore.kernel.org/r/20240527-shm-bridge-v10-4-ce7afaa58d3a@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/firmware/qcom/qcom_scm-smc.c

@@ -2,13 +2,15 @@
 /* Copyright (c) 2015,2019 The Linux Foundation. All rights reserved.
  */
 
+#include <linux/cleanup.h>
 #include <linux/io.h>
 #include <linux/errno.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/firmware/qcom/qcom_scm.h>
+#include <linux/firmware/qcom/qcom_tzmem.h>
 #include <linux/arm-smccc.h>
 #include <linux/dma-mapping.h>
 
@@ -150,11 +152,10 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
 		   enum qcom_scm_convention qcom_convention,
 		   struct qcom_scm_res *res, bool atomic)
 {
+	struct qcom_tzmem_pool *mempool = qcom_scm_get_tzmem_pool();
 	int arglen = desc->arginfo & 0xf;
 	int i, ret;
-	dma_addr_t args_phys = 0;
-	void *args_virt = NULL;
-	size_t alloc_len;
+	void *args_virt __free(qcom_tzmem) = NULL;
 	gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
 	u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
 	u32 qcom_smccc_convention = (qcom_convention == SMC_CONVENTION_ARM_32) ?
@@ -172,9 +173,9 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
 		smc.args[i + SCM_SMC_FIRST_REG_IDX] = desc->args[i];
 
 	if (unlikely(arglen > SCM_SMC_N_REG_ARGS)) {
-		alloc_len = SCM_SMC_N_EXT_ARGS * sizeof(u64);
-		args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
-
+		args_virt = qcom_tzmem_alloc(mempool,
+					     SCM_SMC_N_EXT_ARGS * sizeof(u64),
+					     flag);
 		if (!args_virt)
 			return -ENOMEM;
 
@@ -192,25 +193,10 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
 						      SCM_SMC_FIRST_EXT_IDX]);
 		}
 
-		args_phys = dma_map_single(dev, args_virt, alloc_len,
-					   DMA_TO_DEVICE);
-
-		if (dma_mapping_error(dev, args_phys)) {
-			kfree(args_virt);
-			return -ENOMEM;
-		}
-
-		smc.args[SCM_SMC_LAST_REG_IDX] = args_phys;
+		smc.args[SCM_SMC_LAST_REG_IDX] = qcom_tzmem_to_phys(args_virt);
 	}
 
-	/* ret error check follows after args_virt cleanup*/
 	ret = __scm_smc_do(dev, &smc, &smc_res, atomic);
-
-	if (args_virt) {
-		dma_unmap_single(dev, args_phys, alloc_len, DMA_TO_DEVICE);
-		kfree(args_virt);
-	}
-
 	if (ret)
 		return ret;
 

drivers/firmware/qcom/qcom_scm.c

@@ -203,6 +203,11 @@ static void qcom_scm_bw_disable(void)
 enum qcom_scm_convention qcom_scm_convention = SMC_CONVENTION_UNKNOWN;
 static DEFINE_SPINLOCK(scm_query_lock);
 
+struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void)
+{
+	return __scm->mempool;
+}
+
 static enum qcom_scm_convention __get_convention(void)
 {
 	unsigned long flags;

drivers/firmware/qcom/qcom_scm.h

@@ -5,6 +5,7 @@
 #define __QCOM_SCM_INT_H
 
 struct device;
+struct qcom_tzmem_pool;
 
 enum qcom_scm_convention {
 	SMC_CONVENTION_UNKNOWN,
@@ -78,6 +79,8 @@ int scm_legacy_call_atomic(struct device *dev, const struct qcom_scm_desc *desc,
 int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
 		    struct qcom_scm_res *res);
 
+struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void);
+
 #define QCOM_SCM_SVC_BOOT		0x01
 #define QCOM_SCM_BOOT_SET_ADDR		0x01
 #define QCOM_SCM_BOOT_TERMINATE_PC	0x02