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From:   Bartosz Golaszewski <brgl@bgdev.pl>
To:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Maximilian Luz <luzmaximilian@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        kernel@quicinc.com,
        Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Subject: [PATCH v2 11/11] firmware: qcom: scm: enable SHM bridge
Date:   Thu, 28 Sep 2023 11:20:40 +0200
Message-Id: <20230928092040.9420-12-brgl@bgdev.pl>
In-Reply-To: <20230928092040.9420-1-brgl@bgdev.pl>
References: <20230928092040.9420-1-brgl@bgdev.pl>
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From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Extens the SCM memory allocator with using the SHM Bridge feature if
available on the platform. This makes the trustzone only use dedicated
buffers for SCM calls. We map the entire SCM genpool as a bridge.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/firmware/qcom/qcom_scm-mem.c | 42 ++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/qcom/qcom_scm-mem.c b/drivers/firmware/qcom/qcom_scm-mem.c
index eafecbe23770..12b12b15f46f 100644
--- a/drivers/firmware/qcom/qcom_scm-mem.c
+++ b/drivers/firmware/qcom/qcom_scm-mem.c
@@ -16,6 +16,8 @@
 
 #include "qcom_scm.h"
 
+#define QCOM_SHM_BRIDGE_NUM_VM_SHIFT 9
+
 static size_t qcom_scm_mem_pool_size = SZ_2M;
 module_param_named(qcom_scm_mem_pool_size, qcom_scm_mem_pool_size,
 		   ulong, 0400);
@@ -108,8 +110,24 @@ phys_addr_t qcom_scm_mem_to_phys(void *vaddr)
 	return chunk->paddr;
 }
 
+static int qcom_scm_mem_shm_bridge_create(void)
+{
+	uint64_t pfn_and_ns_perm, ipfn_and_s_perm, size_and_flags, ns_perms;
+
+	ns_perms = (QCOM_SCM_PERM_WRITE | QCOM_SCM_PERM_READ);
+	pfn_and_ns_perm = (u64)qcom_scm_mem.pbase | ns_perms;
+	ipfn_and_s_perm = (u64)qcom_scm_mem.pbase | ns_perms;
+	size_and_flags = qcom_scm_mem.size | (1 << QCOM_SHM_BRIDGE_NUM_VM_SHIFT);
+
+	return qcom_scm_create_shm_bridge(qcom_scm_mem.dev, pfn_and_ns_perm,
+					  ipfn_and_s_perm, size_and_flags,
+					  QCOM_SCM_VMID_HLOS);
+}
+
 int qcom_scm_mem_enable(struct device *dev)
 {
+	int ret;
+
 	INIT_RADIX_TREE(&qcom_scm_mem.chunks, GFP_ATOMIC);
 	spin_lock_init(&qcom_scm_mem.lock);
 	qcom_scm_mem.dev = dev;
@@ -128,7 +146,25 @@ int qcom_scm_mem_enable(struct device *dev)
 
 	gen_pool_set_algo(qcom_scm_mem.pool, gen_pool_best_fit, NULL);
 
-	return gen_pool_add_virt(qcom_scm_mem.pool,
-				 (unsigned long)qcom_scm_mem.vbase,
-				 qcom_scm_mem.pbase, qcom_scm_mem.size, -1);
+	ret = gen_pool_add_virt(qcom_scm_mem.pool,
+				(unsigned long)qcom_scm_mem.vbase,
+				qcom_scm_mem.pbase, qcom_scm_mem.size, -1);
+	if (ret)
+		return ret;
+
+	ret = qcom_scm_enable_shm_bridge();
+	if (ret) {
+		if (ret == EOPNOTSUPP)
+			dev_info(dev, "SHM Bridge not supported\n");
+		else
+			return ret;
+	} else {
+		ret = qcom_scm_mem_shm_bridge_create();
+		if (ret)
+			return ret;
+
+		dev_info(dev, "SHM Bridge enabled\n");
+	}
+
+	return 0;
 }
-- 
2.39.2