linux-kernel - [PATCH v2 1/2] misc: fastrpc: support complete DMA pool access to the DSP

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Message-Id: <20230327184204.498032-2-me@dylanvanassche.be>
Date:   Mon, 27 Mar 2023 20:42:03 +0200
From:   Dylan Van Assche <me@...anvanassche.be>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        Dylan Van Assche <me@...anvanassche.be>
Subject: [PATCH v2 1/2] misc: fastrpc: support complete DMA pool access to the DSP

To support FastRPC Context Banks which aren't mapped via the SMMU,
make the whole reserved memory region available to the DSP to allow
access to coherent buffers.

This is performed by assigning the memory to the DSP via a hypervisor
call to set the correct permissions for the Virtual Machines on the DSP.
This is only necessary when a memory region is provided for SLPI DSPs
so guard this with a domain ID check.

Signed-off-by: Dylan Van Assche <me@...anvanassche.be>
---
 drivers/misc/fastrpc.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index f48466960f1b..caf2ae556956 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -2231,6 +2231,8 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 	int i, err, domain_id = -1, vmcount;
 	const char *domain;
 	bool secure_dsp;
+	struct device_node *rmem_node;
+	struct reserved_mem *rmem;
 	unsigned int vmids[FASTRPC_MAX_VMIDS];
 
 	err = of_property_read_string(rdev->of_node, "label", &domain);
@@ -2274,6 +2276,20 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 		}
 	}
 
+	rmem_node = of_parse_phandle(rdev->of_node, "memory-region", 0);
+	dev_info(rdev, "ASSIGNING MEMORY\n");
+	if (domain_id == SDSP_DOMAIN_ID && rmem_node) {
+		rmem = of_reserved_mem_lookup(rmem_node);
+		if (!rmem)
+			return -EINVAL;
+
+		dev_info(rdev, "ASSIGNING MEMORY START\n");
+		qcom_scm_assign_mem(rmem->base, rmem->size, &data->perms,
+				    data->vmperms, data->vmcount);
+
+		dev_info(rdev, "ASSIGNING MEMORY END\n");
+	}
+
 	secure_dsp = !(of_property_read_bool(rdev->of_node, "qcom,non-secure-domain"));
 	data->secure = secure_dsp;
 
-- 
2.39.2