rpmsg: add rpmsg support for mt8183 SCP.

Add a simple rpmsg support for mt8183 SCP, that use IPI / IPC directly.
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Link: https://lore.kernel.org/r/20191112110330.179649-4-pihsun@chromium.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/Kconfig

@@ -26,6 +26,7 @@ config IMX_REMOTEPROC
 config MTK_SCP
 	tristate "Mediatek SCP support"
 	depends on ARCH_MEDIATEK
+	select RPMSG_MTK_SCP
 	help
 	  Say y here to support Mediatek's System Companion Processor (SCP) via
 	  the remote processor framework.

drivers/remoteproc/mtk_common.h

@@ -70,6 +70,8 @@ struct mtk_scp {
 	void __iomem *cpu_addr;
 	phys_addr_t phys_addr;
 	size_t dram_size;
+
+	struct rproc_subdev *rpmsg_subdev;
 };
 
 /**

drivers/remoteproc/mtk_scp.c

@@ -15,6 +15,7 @@
 #include <linux/platform_device.h>
 #include <linux/remoteproc.h>
 #include <linux/remoteproc/mtk_scp.h>
+#include <linux/rpmsg/mtk_rpmsg.h>
 
 #include "mtk_common.h"
 #include "remoteproc_internal.h"
@@ -464,6 +465,54 @@ static void scp_unmap_memory_region(struct mtk_scp *scp)
 	of_reserved_mem_device_release(scp->dev);
 }
 
+static int scp_register_ipi(struct platform_device *pdev, u32 id,
+			    ipi_handler_t handler, void *priv)
+{
+	struct mtk_scp *scp = platform_get_drvdata(pdev);
+
+	return scp_ipi_register(scp, id, handler, priv);
+}
+
+static void scp_unregister_ipi(struct platform_device *pdev, u32 id)
+{
+	struct mtk_scp *scp = platform_get_drvdata(pdev);
+
+	scp_ipi_unregister(scp, id);
+}
+
+static int scp_send_ipi(struct platform_device *pdev, u32 id, void *buf,
+			unsigned int len, unsigned int wait)
+{
+	struct mtk_scp *scp = platform_get_drvdata(pdev);
+
+	return scp_ipi_send(scp, id, buf, len, wait);
+}
+
+static struct mtk_rpmsg_info mtk_scp_rpmsg_info = {
+	.send_ipi = scp_send_ipi,
+	.register_ipi = scp_register_ipi,
+	.unregister_ipi = scp_unregister_ipi,
+	.ns_ipi_id = SCP_IPI_NS_SERVICE,
+};
+
+static void scp_add_rpmsg_subdev(struct mtk_scp *scp)
+{
+	scp->rpmsg_subdev =
+		mtk_rpmsg_create_rproc_subdev(to_platform_device(scp->dev),
+					      &mtk_scp_rpmsg_info);
+	if (scp->rpmsg_subdev)
+		rproc_add_subdev(scp->rproc, scp->rpmsg_subdev);
+}
+
+static void scp_remove_rpmsg_subdev(struct mtk_scp *scp)
+{
+	if (scp->rpmsg_subdev) {
+		rproc_remove_subdev(scp->rproc, scp->rpmsg_subdev);
+		mtk_rpmsg_destroy_rproc_subdev(scp->rpmsg_subdev);
+		scp->rpmsg_subdev = NULL;
+	}
+}
+
 static int scp_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -544,22 +593,25 @@ static int scp_probe(struct platform_device *pdev)
 	init_waitqueue_head(&scp->run.wq);
 	init_waitqueue_head(&scp->ack_wq);
 
+	scp_add_rpmsg_subdev(scp);
+
 	ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0), NULL,
 					scp_irq_handler, IRQF_ONESHOT,
 					pdev->name, scp);
 
 	if (ret) {
 		dev_err(dev, "failed to request irq\n");
-		goto unregister_ipi;
+		goto remove_subdev;
 	}
 
 	ret = rproc_add(rproc);
 	if (ret)
-		goto unregister_ipi;
+		goto remove_subdev;
 
-	return ret;
+	return 0;
 
-unregister_ipi:
+remove_subdev:
+	scp_remove_rpmsg_subdev(scp);
 	scp_ipi_unregister(scp, SCP_IPI_INIT);
 release_dev_mem:
 	scp_unmap_memory_region(scp);
@@ -579,6 +631,7 @@ static int scp_remove(struct platform_device *pdev)
 	int i;
 
 	rproc_del(scp->rproc);
+	scp_remove_rpmsg_subdev(scp);
 	scp_ipi_unregister(scp, SCP_IPI_INIT);
 	scp_unmap_memory_region(scp);
 	for (i = 0; i < SCP_IPI_MAX; i++)

drivers/remoteproc/mtk_scp_ipi.c

@@ -162,6 +162,7 @@ int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
 	int ret;
 
 	if (WARN_ON(id <= SCP_IPI_INIT) || WARN_ON(id >= SCP_IPI_MAX) ||
+	    WARN_ON(id == SCP_IPI_NS_SERVICE) ||
 	    WARN_ON(len > sizeof(send_obj->share_buf)) || WARN_ON(!buf))
 		return -EINVAL;
 

drivers/rpmsg/Kconfig

@@ -15,6 +15,15 @@ config RPMSG_CHAR
 	  in /dev. They make it possible for user-space programs to send and
 	  receive rpmsg packets.
 
+config RPMSG_MTK_SCP
+	tristate "MediaTek SCP"
+	depends on MTK_SCP
+	select RPMSG
+	help
+	  Say y here to enable support providing communication channels to
+	  remote processors in MediaTek platforms.
+	  This use IPI and IPC to communicate with remote processors.
+
 config RPMSG_QCOM_GLINK_NATIVE
 	tristate
 	select RPMSG

drivers/rpmsg/Makefile

 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_RPMSG)		+= rpmsg_core.o
 obj-$(CONFIG_RPMSG_CHAR)	+= rpmsg_char.o
+obj-$(CONFIG_RPMSG_MTK_SCP)	+= mtk_rpmsg.o
 obj-$(CONFIG_RPMSG_QCOM_GLINK_RPM) += qcom_glink_rpm.o
 obj-$(CONFIG_RPMSG_QCOM_GLINK_NATIVE) += qcom_glink_native.o
 obj-$(CONFIG_RPMSG_QCOM_GLINK_SMEM) += qcom_glink_smem.o

include/linux/remoteproc/mtk_scp.h

@@ -41,7 +41,8 @@ enum scp_ipi_id {
 	SCP_IPI_ISP_FRAME,
 	SCP_IPI_FD_CMD,
 	SCP_IPI_CROS_HOST_CMD,
-	SCP_IPI_MAX,
+	SCP_IPI_NS_SERVICE = 0xFF,
+	SCP_IPI_MAX = 0x100,
 };
 
 struct mtk_scp *scp_get(struct platform_device *pdev);

include/linux/rpmsg/mtk_rpmsg.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2019 Google LLC.
+ */
+
+#ifndef __LINUX_RPMSG_MTK_RPMSG_H
+#define __LINUX_RPMSG_MTK_RPMSG_H
+
+#include <linux/platform_device.h>
+#include <linux/remoteproc.h>
+
+typedef void (*ipi_handler_t)(void *data, unsigned int len, void *priv);
+
+/*
+ * struct mtk_rpmsg_info - IPI functions tied to the rpmsg device.
+ * @register_ipi: register IPI handler for an IPI id.
+ * @unregister_ipi: unregister IPI handler for a registered IPI id.
+ * @send_ipi: send IPI to an IPI id. wait is the timeout (in msecs) to wait
+ *            until response, or 0 if there's no timeout.
+ * @ns_ipi_id: the IPI id used for name service, or -1 if name service isn't
+ *             supported.
+ */
+struct mtk_rpmsg_info {
+	int (*register_ipi)(struct platform_device *pdev, u32 id,
+			    ipi_handler_t handler, void *priv);
+	void (*unregister_ipi)(struct platform_device *pdev, u32 id);
+	int (*send_ipi)(struct platform_device *pdev, u32 id,
+			void *buf, unsigned int len, unsigned int wait);
+	int ns_ipi_id;
+};
+
+struct rproc_subdev *
+mtk_rpmsg_create_rproc_subdev(struct platform_device *pdev,
+			      struct mtk_rpmsg_info *info);
+
+void mtk_rpmsg_destroy_rproc_subdev(struct rproc_subdev *subdev);
+
+#endif