Message-Id: <20210205225204.32902-19-mgross@linux.intel.com>
Date:   Fri,  5 Feb 2021 14:51:48 -0800
From:   mgross@...ux.intel.com
To:     markgross@...nel.org, mgross@...ux.intel.com, arnd@...db.de,
        bp@...e.de, damien.lemoal@....com, dragan.cvetic@...inx.com,
        gregkh@...uxfoundation.org, corbet@....net,
        palmerdabbelt@...gle.com, paul.walmsley@...ive.com,
        peng.fan@....com, robh+dt@...nel.org, shawnguo@...nel.org,
        jassisinghbrar@...il.com
Cc:     linux-kernel@...r.kernel.org,
        Seamus Kelly <seamus.kelly@...el.com>,
        "Cc : Derek Kiernan" <derek.kiernan@...inx.com>,
        linux-doc@...r.kernel.org
Subject: [PATCH v5 18/34] xlink-ipc: Add xlink ipc driver

From: Seamus Kelly <seamus.kelly@...el.com>

Add xLink driver, which interfaces the xLink Core driver with the Keem
Bay VPU IPC driver, thus enabling xLink to control and communicate with
the VPU IP present on the Intel Keem Bay SoC.

Specifically the driver enables xLink Core to:

* Boot / Reset the VPU IP
* Register to VPU IP event notifications (device connected, device
  disconnected, WDT event)
* Query the status of the VPU IP (OFF, BUSY, READY, ERROR, RECOVERY)
* Exchange data with the VPU IP, using the Keem Bay IPC mechanism
  - Including the ability to send 'volatile' data (i.e., small amount of
    data, up to 128-bytes that was not allocated in the CPU/VPU shared
    memory region)

Cc: Jonathan Corbet <corbet@....net>
Cc: Cc: Derek Kiernan <derek.kiernan@...inx.com>
Cc: Dragan Cvetic <dragan.cvetic@...inx.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-doc@...r.kernel.org
Reviewed-by: Mark Gross <mgross@...ux.intel.com>
Signed-off-by: Mark Gross <mgross@...ux.intel.com>
Signed-off-by: Seamus Kelly <seamus.kelly@...el.com>
---
 Documentation/vpu/index.rst        |   1 +
 Documentation/vpu/xlink-ipc.rst    |  51 ++
 MAINTAINERS                        |   6 +
 drivers/misc/Kconfig               |   1 +
 drivers/misc/Makefile              |   1 +
 drivers/misc/xlink-ipc/Kconfig     |   7 +
 drivers/misc/xlink-ipc/Makefile    |   4 +
 drivers/misc/xlink-ipc/xlink-ipc.c | 878 +++++++++++++++++++++++++++++
 include/linux/xlink-ipc.h          |  48 ++
 9 files changed, 997 insertions(+)
 create mode 100644 Documentation/vpu/xlink-ipc.rst
 create mode 100644 drivers/misc/xlink-ipc/Kconfig
 create mode 100644 drivers/misc/xlink-ipc/Makefile
 create mode 100644 drivers/misc/xlink-ipc/xlink-ipc.c
 create mode 100644 include/linux/xlink-ipc.h

diff --git a/Documentation/vpu/index.rst b/Documentation/vpu/index.rst
index 661cc700ee45..49c78bb65b83 100644
--- a/Documentation/vpu/index.rst
+++ b/Documentation/vpu/index.rst
@@ -15,3 +15,4 @@ This documentation contains information for the Intel VPU stack.
 
    vpu-stack-overview
    xlink-pcie
+   xlink-ipc
diff --git a/Documentation/vpu/xlink-ipc.rst b/Documentation/vpu/xlink-ipc.rst
new file mode 100644
index 000000000000..97ee62b10e93
--- /dev/null
+++ b/Documentation/vpu/xlink-ipc.rst
@@ -0,0 +1,51 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============================
+Kernel driver: xLink IPC driver
+===============================
+
+Supported chips:
+
+* | Intel Edge.AI Computer Vision platforms: Keem Bay
+  | Suffix: Bay
+  | Datasheet: (not yet publicly available)
+
+Introduction
+============
+
+The xLink IPC driver interfaces the xLink Core driver with the Keem Bay VPU IPC
+driver, thus enabling xLink to control and communicate with the VPU IP present
+on the Intel Keem Bay SoC.
+
+Specifically the driver enables xLink Core to:
+
+* Boot / Reset the VPU IP
+* Register to VPU IP event notifications (device connected, device disconnected,
+  WDT event)
+* Query the status of the VPU IP (OFF, BUSY, READY, ERROR, RECOVERY)
+* Exchange data with the VPU IP, using the Keem Bay IPC mechanism
+
+  * Including the ability to send 'volatile' data (i.e. small amounts of data,
+    up to 128-bytes that was not allocated in the CPU/VPU shared memory region)
+
+Sending / Receiving 'volatile' data
+===================================
+
+Data to be exchanged with Keem Bay IPC needs to be allocated in the portion of
+DDR shared between the CPU and VPU.
+
+This can be impractical for small amounts of data that user code can allocate
+on the stack.
+
+To reduce the burden on user code, xLink Core provides special send / receive
+functions to send up to 128 bytes of 'volatile data', i.e., data that is not
+allocated in the shared memory and that might also disappear after the xLink
+API is called (e.g., because allocated on the stack).
+
+The xLink IPC driver implements support for transferring such 'volatile data'
+to the VPU using Keem Bay IPC. To this end, the driver reserves some memory in
+the shared memory region.
+
+When volatile data is to be sent, xLink IPC allocates a buffer from the
+reserved memory region and copies the volatile data to the buffer. The buffer
+is then transferred to the VPU using Keem Bay IPC.
diff --git a/MAINTAINERS b/MAINTAINERS
index 1d825e6c3c53..8c79b879db8b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1961,6 +1961,12 @@ F:	Documentation/devicetree/bindings/arm/intel,keembay.yaml
 F:	arch/arm64/boot/dts/intel/keembay-evm.dts
 F:	arch/arm64/boot/dts/intel/keembay-soc.dtsi
 
+ARM/INTEL XLINK IPC SUPPORT
+M:	Seamus Kelly <seamus.kelly@...el.com>
+M:	Mark Gross <mgross@...ux.intel.com>
+S:	Supported
+F:	drivers/misc/xlink-ipc/
+
 ARM/INTEL KEEM BAY XLINK PCIE SUPPORT
 M:	Srikanth Thokala <srikanth.thokala@...el.com>
 M:	Mark Gross <mgross@...ux.intel.com>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index dfb98e444c6e..1f81ea915b95 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -482,4 +482,5 @@ source "drivers/misc/cardreader/Kconfig"
 source "drivers/misc/habanalabs/Kconfig"
 source "drivers/misc/uacce/Kconfig"
 source "drivers/misc/xlink-pcie/Kconfig"
+source "drivers/misc/xlink-ipc/Kconfig"
 endmenu
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index d17621fc43d5..b51495a2f1e0 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -58,3 +58,4 @@ obj-$(CONFIG_UACCE)		+= uacce/
 obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o
 obj-$(CONFIG_HISI_HIKEY_USB)	+= hisi_hikey_usb.o
 obj-y                           += xlink-pcie/
+obj-$(CONFIG_XLINK_IPC)		+= xlink-ipc/
diff --git a/drivers/misc/xlink-ipc/Kconfig b/drivers/misc/xlink-ipc/Kconfig
new file mode 100644
index 000000000000..6e5374c7d85c
--- /dev/null
+++ b/drivers/misc/xlink-ipc/Kconfig
@@ -0,0 +1,7 @@
+config XLINK_IPC
+	tristate "Support for XLINK IPC"
+	depends on KEEMBAY_VPU_IPC
+	help
+	  XLINK IPC enables the communication/control IPC Sub-System.
+
+	  Select M if you have an Intel SoC with a Vision Processing Unit (VPU).
diff --git a/drivers/misc/xlink-ipc/Makefile b/drivers/misc/xlink-ipc/Makefile
new file mode 100644
index 000000000000..f92c95525e23
--- /dev/null
+++ b/drivers/misc/xlink-ipc/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for xlink IPC Linux driver
+#
+obj-$(CONFIG_XLINK_IPC) += xlink-ipc.o
diff --git a/drivers/misc/xlink-ipc/xlink-ipc.c b/drivers/misc/xlink-ipc/xlink-ipc.c
new file mode 100644
index 000000000000..e98a5a4b66a2
--- /dev/null
+++ b/drivers/misc/xlink-ipc/xlink-ipc.c
@@ -0,0 +1,878 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * xlink Linux Kernel Platform API
+ *
+ * Copyright (C) 2018-2020 Intel Corporation
+ *
+ */
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <linux/soc/intel/keembay-vpu-ipc.h>
+
+#include <linux/xlink-ipc.h>
+
+#define XLINK_IPC_MAX_DEVICE_NAME_SIZE	12
+
+/* used to extract fields from and create xlink sw device id */
+#define SW_DEVICE_ID_INTERFACE_SHIFT	24U
+#define SW_DEVICE_ID_INTERFACE_MASK	0x7
+#define SW_DEVICE_ID_INTERFACE_SMASK \
+		(SW_DEVICE_ID_INTERFACE_MASK << SW_DEVICE_ID_INTERFACE_SHIFT)
+#define SW_DEVICE_ID_INTERFACE_IPC_VALUE 0x0
+#define SW_DEVICE_ID_INTERFACE_IPC_SVALUE \
+		(SW_DEVICE_ID_INTERFACE_IPC_VALUE << SW_DEVICE_ID_INTERFACE_SHIFT)
+#define SW_DEVICE_ID_VPU_ID_SHIFT 1U
+#define SW_DEVICE_ID_VPU_ID_MASK 0x7
+#define SW_DEVICE_ID_VPU_ID_SMASK \
+		(SW_DEVICE_ID_VPU_ID_MASK << SW_DEVICE_ID_VPU_ID_SHIFT)
+#define GET_VPU_ID_FROM_SW_DEVICE_ID(id) \
+		(((id) >> SW_DEVICE_ID_VPU_ID_SHIFT) & SW_DEVICE_ID_VPU_ID_MASK)
+#define GET_SW_DEVICE_ID_FROM_VPU_ID(id) \
+		((((id) << SW_DEVICE_ID_VPU_ID_SHIFT) & SW_DEVICE_ID_VPU_ID_SMASK) \
+		| SW_DEVICE_ID_INTERFACE_IPC_SVALUE)
+
+/* the maximum buffer size for volatile xlink operations */
+#define XLINK_MAX_BUF_SIZE 128U
+
+/* indices used to retrieve reserved memory from the dt */
+#define LOCAL_XLINK_IPC_BUFFER_IDX	0
+#define REMOTE_XLINK_IPC_BUFFER_IDX	1
+
+/* index used to retrieve the vpu ipc device phandle from the dt */
+#define VPU_IPC_DEVICE_PHANDLE_IDX	1
+
+/* the timeout (in ms) used to wait for the vpu ready message */
+#define XLINK_VPU_WAIT_FOR_READY_MS 3000
+
+/* xlink buffer memory region */
+struct xlink_buf_mem {
+	struct device *dev;	/* child device managing the memory region */
+	void *vaddr;		/* the virtual address of the memory region */
+	dma_addr_t dma_handle;	/* the physical address of the memory region */
+	size_t size;		/* the size of the memory region */
+};
+
+/* xlink buffer pool */
+struct xlink_buf_pool {
+	void *buf;		/* pointer to the start of pool area */
+	size_t buf_cnt;		/* pool size (i.e., number of buffers) */
+	size_t idx;		/* current index */
+	spinlock_t lock;	/* the lock protecting this pool */
+};
+
+/* xlink ipc device */
+struct xlink_ipc_dev {
+	struct platform_device *pdev;		/* pointer to platform device */
+	u32 vpu_id;				/* The VPU ID defined in the device tree */
+	u32 sw_device_id;			/* the sw device id */
+	const char *device_name;		/* the vpu device name */
+	struct xlink_buf_mem local_xlink_mem;	/* tx buffer memory region */
+	struct xlink_buf_mem remote_xlink_mem;	/* rx buffer memory region */
+	struct xlink_buf_pool xlink_buf_pool;	/* tx buffer pool */
+	struct device *vpu_dev;			/* pointer to vpu ipc device */
+	int (*callback)(u32 sw_device_id, u32 event);
+};
+
+/* Events that can be notified via callback, when registered. */
+enum xlink_vpu_event {
+	XLINK_VPU_NOTIFY_DISCONNECT = 0,
+	XLINK_VPU_NOTIFY_CONNECT,
+	XLINK_VPU_NOTIFY_MSS_WDT,
+	XLINK_VPU_NOTIFY_NCE_WDT,
+	NUM_EVENT_TYPE
+};
+
+#define VPU_ID 0
+#define VPU_DEVICE_NAME "vpu-0"
+#define VPU_SW_DEVICE_ID 0
+static struct xlink_ipc_dev *xlink_dev;
+
+/*
+ * Functions related to reserved-memory sub-devices.
+ */
+
+/*
+ * xlink_reserved_memory_remove() - Removes the reserved memory sub-devices.
+ *
+ * @xlink_dev: [in] The xlink ipc device with reserved memory sub-devices.
+ */
+static void xlink_reserved_memory_remove(struct xlink_ipc_dev *xlink_dev)
+{
+	device_unregister(xlink_dev->local_xlink_mem.dev);
+	device_unregister(xlink_dev->remote_xlink_mem.dev);
+}
+
+/*
+ * xlink_reserved_mem_release() - Reserved memory release callback function.
+ *
+ * @dev: [in] The reserved memory sub-device.
+ */
+static void xlink_reserved_mem_release(struct device *dev)
+{
+	of_reserved_mem_device_release(dev);
+}
+
+/*
+ * get_xlink_reserved_mem_size() - Gets the size of the reserved memory region.
+ *
+ * @dev: [in] The device the reserved memory region is allocated to.
+ * @idx: [in] The reserved memory region's index in the phandle table.
+ *
+ * Return: The reserved memory size, 0 on failure.
+ */
+static resource_size_t get_xlink_reserved_mem_size(struct device *dev, int idx)
+{
+	struct device_node *np;
+	struct resource mem;
+	int rc;
+
+	np = of_parse_phandle(dev->of_node, "memory-region", idx);
+	if (!np) {
+		dev_err(dev, "Couldn't find memory-region %d\n", idx);
+		return 0;
+	}
+
+	rc = of_address_to_resource(np, 0, &mem);
+	if (rc) {
+		dev_err(dev, "Couldn't map address to resource %d\n", idx);
+		return 0;
+	}
+	return resource_size(&mem);
+}
+
+/*
+ * init_xlink_reserved_mem_dev() - Initializes the reserved memory sub-devices.
+ *
+ * @dev:	[in] The parent device of the reserved memory sub-device.
+ * @name:	[in] The name to assign to the memory region.
+ * @idx:	[in] The reserved memory region index in the phandle table.
+ *
+ * Return: The initialized sub-device, NULL on failure.
+ */
+static struct device *init_xlink_reserved_mem_dev(struct device *dev,
+						  const char *name, int idx)
+{
+	struct device *child;
+	int rc;
+
+	child = devm_kzalloc(dev, sizeof(*child), GFP_KERNEL);
+	if (!child)
+		return NULL;
+
+	device_initialize(child);
+	dev_set_name(child, "%s:%s", dev_name(dev), name);
+	dev_err(dev, " dev_name %s, name %s\n", dev_name(dev), name);
+	child->parent = dev;
+	child->dma_mask = dev->dma_mask;
+	child->coherent_dma_mask = dev->coherent_dma_mask;
+	/* set up dma configuration using information from parent's dt node */
+	rc = of_dma_configure(child, dev->of_node, true);
+	if (rc)
+		return NULL;
+	child->release = xlink_reserved_mem_release;
+
+	rc = device_add(child);
+	if (rc)
+		goto err;
+	rc = of_reserved_mem_device_init_by_idx(child, dev->of_node, idx);
+	if (rc) {
+		dev_err(dev, "Couldn't get reserved memory with idx = %d, %d\n",
+			idx, rc);
+		device_del(child);
+		goto err;
+	}
+	return child;
+
+err:
+	put_device(child);
+	return NULL;
+}
+
+/*
+ * xlink_reserved_memory_init() - Initialize reserved memory for the device.
+ *
+ * @xlink_dev:	[in] The xlink ipc device the reserved memory is allocated to.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int xlink_reserved_memory_init(struct xlink_ipc_dev *xlink_dev)
+{
+	struct device *dev = &xlink_dev->pdev->dev;
+	struct xlink_buf_mem *lxm = &xlink_dev->local_xlink_mem;
+	struct xlink_buf_mem *rxm = &xlink_dev->remote_xlink_mem;
+
+	lxm->dev = init_xlink_reserved_mem_dev(dev, "xlink_local_reserved",
+					       LOCAL_XLINK_IPC_BUFFER_IDX);
+	if (!lxm->dev)
+		return -ENOMEM;
+
+	lxm->size = get_xlink_reserved_mem_size(dev, LOCAL_XLINK_IPC_BUFFER_IDX);
+
+	rxm->dev = init_xlink_reserved_mem_dev(dev, "xlink_remote_reserved",
+					       REMOTE_XLINK_IPC_BUFFER_IDX);
+	if (!rxm->dev) {
+		device_unregister(xlink_dev->local_xlink_mem.dev);
+		return -ENOMEM;
+	}
+
+	rxm->size = get_xlink_reserved_mem_size(dev, REMOTE_XLINK_IPC_BUFFER_IDX);
+
+	return 0;
+}
+
+/*
+ * xlink_reserved_memory_alloc() - Allocate reserved memory for the device.
+ *
+ * @xlink_dev:	[in] The xlink ipc device.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int xlink_reserved_memory_alloc(struct xlink_ipc_dev *xlink_dev)
+{
+	struct xlink_buf_mem *lxm = &xlink_dev->local_xlink_mem;
+	struct xlink_buf_mem *rxm = &xlink_dev->remote_xlink_mem;
+
+	lxm->vaddr = dmam_alloc_coherent(xlink_dev->local_xlink_mem.dev,
+					 xlink_dev->local_xlink_mem.size,
+					 &xlink_dev->local_xlink_mem.dma_handle,
+					 GFP_KERNEL);
+	if (!lxm->vaddr) {
+		dev_err(&xlink_dev->pdev->dev,
+			"Failed to allocate from local reserved memory.\n");
+		return -ENOMEM;
+	}
+	rxm->vaddr = dmam_alloc_coherent(xlink_dev->remote_xlink_mem.dev,
+					 xlink_dev->remote_xlink_mem.size,
+					 &xlink_dev->remote_xlink_mem.dma_handle,
+					 GFP_KERNEL);
+	if (!rxm->vaddr) {
+		dev_err(&xlink_dev->pdev->dev,
+			"Failed to allocate from remote reserved memory.\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/*
+ * init_xlink_buf_pool() - Initialize the device's tx buffer pool.
+ *
+ * @xlink_dev:	[in] The xlink ipc device.
+ *
+ * Return: 0 on success.
+ */
+static int init_xlink_buf_pool(struct xlink_ipc_dev *xlink_dev)
+{
+	struct xlink_buf_mem *mem = &xlink_dev->local_xlink_mem;
+	struct xlink_buf_pool *xbufpool = &xlink_dev->xlink_buf_pool;
+
+	memset(mem->vaddr, 0, mem->size);
+	xbufpool->buf = mem->vaddr;
+	xbufpool->buf_cnt = mem->size / XLINK_MAX_BUF_SIZE;
+	xbufpool->idx = 0;
+	dev_info(&xlink_dev->pdev->dev, "xlink Buffer Pool size: %zX\n",
+		 xbufpool->buf_cnt);
+	spin_lock_init(&xbufpool->lock);
+
+	return 0;
+}
+
+/*
+ * xlink_phys_to_virt() - Convert an xlink physical addresses to a virtual one.
+ *
+ * @xlink_mem:	[in] The memory region where the physical address is located.
+ * @paddr:		[in] The physical address to convert to a virtual one.
+ *
+ * Return:		The corresponding virtual address, or NULL if the
+ *				physical address is not in the expected memory
+ *				range.
+ */
+static void *xlink_phys_to_virt(const struct xlink_buf_mem *xlink_mem,
+				u32 paddr)
+{
+	if (unlikely(paddr < xlink_mem->dma_handle) ||
+	    paddr >= (xlink_mem->dma_handle + xlink_mem->size))
+		return NULL;
+
+	return xlink_mem->vaddr + (paddr - xlink_mem->dma_handle);
+}
+
+/*
+ * xlink_virt_to_phys() - Convert an xlink virtual addresses to a physical one.
+ *
+ * @xlink_mem:	[in]  The memory region where the physical address is located.
+ * @vaddr:		[in]  The virtual address to convert to a physical one.
+ * @paddr:		[out] Where to store the computed physical address.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int xlink_virt_to_phys(struct xlink_buf_mem *xlink_mem, void *vaddr,
+			      u32 *paddr)
+{
+	if (unlikely((xlink_mem->dma_handle + xlink_mem->size) > 0xFFFFFFFF))
+		return -EINVAL;
+	if (unlikely(vaddr < xlink_mem->vaddr ||
+		     vaddr >= (xlink_mem->vaddr + xlink_mem->size)))
+		return -EINVAL;
+	*paddr = xlink_mem->dma_handle + (vaddr - xlink_mem->vaddr);
+
+	return 0;
+}
+
+/*
+ * get_next_xlink_buf() - Get next xlink buffer from an xlink device's pool.
+ *
+ * @xlink_dev:	[in]  The xlink ipc device to get a buffer from.
+ * @buf:		[out] Where to store the reference to the next buffer.
+ * @size:		[in]  The size of the buffer to get.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int get_next_xlink_buf(struct xlink_ipc_dev *xlink_dev, void **buf,
+			      int size)
+{
+	struct xlink_buf_pool *pool;
+	unsigned long flags;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	if (size > XLINK_MAX_BUF_SIZE)
+		return -EINVAL;
+
+	pool = &xlink_dev->xlink_buf_pool;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	if (pool->idx == pool->buf_cnt) {
+		/* reached end of buffers - wrap around */
+		pool->idx = 0;
+	}
+	*buf = pool->buf + (pool->idx * XLINK_MAX_BUF_SIZE);
+	pool->idx++;
+	spin_unlock_irqrestore(&pool->lock, flags);
+	return 0;
+}
+
+/*
+ * Functions related to the vpu ipc device reference.
+ */
+
+/*
+ * vpu_ipc_device_put() - Release the vpu ipc device held by the xlink device.
+ *
+ * @xlink_dev:	[in] The xlink ipc device.
+ */
+static void vpu_ipc_device_put(struct xlink_ipc_dev *xlink_dev)
+{
+	put_device(xlink_dev->vpu_dev);
+}
+
+/*
+ * vpu_ipc_device_get() - Get the vpu ipc device reference for the xlink device.
+ *
+ * @xlink_dev:	[in] The xlink ipc device.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int vpu_ipc_device_get(struct xlink_ipc_dev *xlink_dev)
+{
+	struct device *dev = &xlink_dev->pdev->dev;
+	struct platform_device *pdev;
+	struct device_node *np;
+
+	np = of_parse_phandle(dev->of_node, "intel,keembay-vpu-ipc", 0);
+	if (!np)
+		return -ENODEV;
+
+	pdev = of_find_device_by_node(np);
+	if (!pdev) {
+		dev_info(dev, "IPC device not probed\n");
+		of_node_put(np);
+		return -EPROBE_DEFER;
+	}
+
+	xlink_dev->vpu_dev = get_device(&pdev->dev);
+	of_node_put(np);
+
+	dev_info(dev, "Using IPC device: %s\n", dev_name(xlink_dev->vpu_dev));
+	return 0;
+}
+
+/*
+ * xlink platform api - ipc interface functions
+ */
+
+/*
+ * xlink_ipc_connect() - platform connect interface.
+ *
+ * @sw_device_id:	[in]  The sw device id of the device to connect to.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_connect(u32 sw_device_id)
+{
+	if (!xlink_dev)
+		return -ENODEV;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_connect);
+
+/*
+ * xlink_ipc_write() - platform write interface.
+ *
+ * @sw_device_id:	[in]     The sw device id of the device to write to.
+ * @data:			[in]     The data buffer to write.
+ * @size:			[in-out] The amount of data to write/written.
+ * @timeout:		[in]     The time (in ms) to wait before timing out.
+ * @context:		[in]     The ipc operation context.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_write(u32 sw_device_id, void *data, size_t * const size,
+		    u32 timeout, void *context)
+{
+	struct xlink_ipc_context *ctx = context;
+	void *vaddr = NULL;
+	u32 paddr;
+	int rc;
+
+	if (!ctx)
+		return -EINVAL;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	if (ctx->is_volatile) {
+		rc = get_next_xlink_buf(xlink_dev, &vaddr, XLINK_MAX_BUF_SIZE);
+		if (rc)
+			return rc;
+		memcpy(vaddr, data, *size);
+		rc = xlink_virt_to_phys(&xlink_dev->local_xlink_mem, vaddr,
+					&paddr);
+		if (rc)
+			return rc;
+	} else {
+		paddr = *(u32 *)data;
+	}
+	rc = intel_keembay_vpu_ipc_send(xlink_dev->vpu_dev,
+					KMB_VPU_IPC_NODE_LEON_MSS, ctx->chan,
+					paddr, *size);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_write);
+
+/*
+ * xlink_ipc_read() - platform read interface.
+ *
+ * @sw_device_id:	[in]     The sw device id of the device to read from.
+ * @data:			[out]    The data buffer to read into.
+ * @size:			[in-out] The amount of data to read/was read.
+ * @timeout:		[in]     The time (in ms) to wait before timing out.
+ * @context:		[in]     The ipc operation context.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_read(u32 sw_device_id, void *data, size_t * const size,
+		   u32 timeout, void *context)
+{
+	struct xlink_ipc_context *ctx = context;
+	u32 addr = 0;
+	void *vaddr;
+	int rc;
+
+	if (!ctx)
+		return -EINVAL;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	rc = intel_keembay_vpu_ipc_recv(xlink_dev->vpu_dev,
+					KMB_VPU_IPC_NODE_LEON_MSS, ctx->chan,
+					&addr, size, timeout);
+
+	if (ctx->is_volatile) {
+		vaddr = xlink_phys_to_virt(&xlink_dev->remote_xlink_mem, addr);
+		if (vaddr)
+			memcpy(data, vaddr, *size);
+		else
+			return -ENXIO;
+	} else {
+		*(u32 *)data = addr;
+	}
+	return rc;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_read);
+
+/*
+ * xlink_ipc_get_device_list() - platform get device list interface.
+ *
+ * @sw_device_id_list:	[out]  The list of devices found.
+ * @num_devices:		[out]  The number of devices found.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_get_device_list(u32 *sw_device_id_list, u32 *num_devices)
+{
+	int i = 0;
+
+	if (!sw_device_id_list || !num_devices)
+		return -EINVAL;
+
+	if (xlink_dev) {
+		*sw_device_id_list = xlink_dev->sw_device_id;
+		i++;
+	}
+
+	*num_devices = i;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_get_device_list);
+
+/*
+ * xlink_ipc_get_device_name() - platform get device name interface.
+ *
+ * @sw_device_id:	[in]  The sw device id of the device to get name of.
+ * @device_name:	[out] The name of the xlink ipc device.
+ * @name_size:		[in]  The maximum size of the name.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_get_device_name(u32 sw_device_id, char *device_name,
+			      size_t name_size)
+{
+	size_t size;
+
+	if (!device_name)
+		return -EINVAL;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	size = (name_size > XLINK_IPC_MAX_DEVICE_NAME_SIZE)
+			? XLINK_IPC_MAX_DEVICE_NAME_SIZE
+			: name_size;
+	strncpy(device_name, xlink_dev->device_name, size);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_get_device_name);
+
+/*
+ * xlink_ipc_get_device_status() - platform get device status interface.
+ *
+ * @sw_device_id:	[in]  The sw device id of the device to get status of.
+ * @device_status:	[out] The device status.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_get_device_status(u32 sw_device_id, u32 *device_status)
+{
+	if (!device_status)
+		return -EINVAL;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	*device_status = intel_keembay_vpu_status(xlink_dev->vpu_dev);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_get_device_status);
+
+static void kernel_callback(struct device *dev, enum intel_keembay_vpu_event event)
+{
+	if ((enum xlink_vpu_event)event >= NUM_EVENT_TYPE)
+		return;
+
+	if (xlink_dev) {
+		if (xlink_dev->callback)
+			xlink_dev->callback(xlink_dev->sw_device_id, event);
+	}
+}
+
+/*
+ * xlink_ipc_register_for_events() - platform register for events
+ *
+ * @sw_device_id:	[in]	The sw device id of the device to get status of.
+ * @callback:		[in]	Callback function for events
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_register_for_events(u32 sw_device_id,
+				  int (*callback)(u32 sw_device_id, enum xlink_vpu_event event))
+{
+	int rc;
+
+	if (!xlink_dev)
+		return -ENODEV;
+	xlink_dev->callback = callback;
+	rc = intel_keembay_vpu_register_for_events(xlink_dev->vpu_dev, kernel_callback);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_register_for_events);
+/*
+ * xlink_ipc_unregister_for_events() - platform register for events
+ *
+ * @sw_device_id:	[in]	The sw device id of the device to get status of.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_unregister_for_events(u32 sw_device_id)
+{
+	int rc;
+
+	if (!xlink_dev)
+		return -ENODEV;
+	rc = intel_keembay_vpu_unregister_for_events(xlink_dev->vpu_dev);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_unregister_for_events);
+
+/*
+ * xlink_ipc_boot_device() - platform boot device interface.
+ *
+ * @sw_device_id:	[in] The sw device id of the device to boot.
+ * @binary_name:	[in] The file name of the firmware binary to boot.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_boot_device(u32 sw_device_id, const char *binary_name)
+{
+	enum intel_keembay_vpu_state state;
+	int rc;
+
+	if (!binary_name)
+		return -EINVAL;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	pr_info("\nStart VPU 0x%x - %s\n", sw_device_id, binary_name);
+	rc = intel_keembay_vpu_startup(xlink_dev->vpu_dev, binary_name);
+	if (rc) {
+		pr_err("Failed to start VPU: %d\n", rc);
+		return -EBUSY;
+	}
+	pr_info("Successfully started VPU!\n");
+
+	/* Wait for VPU to be READY */
+	rc = intel_keembay_vpu_wait_for_ready(xlink_dev->vpu_dev,
+					      XLINK_VPU_WAIT_FOR_READY_MS);
+	if (rc) {
+		pr_err("Tried to start VPU but never got READY.\n");
+		return -EBUSY;
+	}
+	pr_info("Successfully synchronised state with VPU!\n");
+
+	/* Check state */
+	state = intel_keembay_vpu_status(xlink_dev->vpu_dev);
+	if (state != KEEMBAY_VPU_READY) {
+		pr_err("VPU was not ready, it was %d\n", state);
+		return -EBUSY;
+	}
+	pr_info("VPU was ready.\n");
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_boot_device);
+
+/*
+ * xlink_ipc_reset_device() - platform reset device interface.
+ *
+ * @sw_device_id:	[in] The sw device id of the device to reset.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_reset_device(u32 sw_device_id)
+{
+	enum intel_keembay_vpu_state state;
+	int rc;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	/* stop the vpu */
+	rc = intel_keembay_vpu_stop(xlink_dev->vpu_dev);
+	if (rc) {
+		pr_err("Failed to stop VPU: %d\n", rc);
+		return -EBUSY;
+	}
+	pr_info("Successfully stopped VPU!\n");
+
+	/* check state */
+	state = intel_keembay_vpu_status(xlink_dev->vpu_dev);
+	if (state != KEEMBAY_VPU_OFF) {
+		pr_err("VPU was not OFF after stop request, it was %d\n",
+		       state);
+		return -EBUSY;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_reset_device);
+
+/*
+ * xlink_ipc_open_channel() - platform open channel interface.
+ *
+ * @sw_device_id:	[in] The sw device id of the device to open channel to.
+ * @channel:		[in] The channel id to open.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_open_channel(u32 sw_device_id, u32 channel)
+{
+	int rc;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	rc = intel_keembay_vpu_ipc_open_channel(xlink_dev->vpu_dev,
+						KMB_VPU_IPC_NODE_LEON_MSS, channel);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_open_channel);
+
+/*
+ * xlink_ipc_close_channel() - platform close channel interface.
+ *
+ * @sw_device_id:	[in] The sw device id of the device to close channel to.
+ * @channel:		[in] The channel id to close.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int xlink_ipc_close_channel(u32 sw_device_id, u32 channel)
+{
+	int rc;
+
+	if (!xlink_dev)
+		return -ENODEV;
+
+	rc = intel_keembay_vpu_ipc_close_channel(xlink_dev->vpu_dev,
+						 KMB_VPU_IPC_NODE_LEON_MSS, channel);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(xlink_ipc_close_channel);
+
+/*
+ * xlink ipc driver functions
+ */
+
+static int keembay_xlink_ipc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	int rc;
+
+	/* allocate device data structure */
+	xlink_dev = kzalloc(sizeof(*xlink_dev), GFP_KERNEL);
+	if (!xlink_dev)
+		return -ENOMEM;
+
+	xlink_dev->pdev = pdev;
+	dev_info(dev, "Keem Bay xlink IPC driver probed.\n");
+
+	/* grab reserved memory regions and assign to child devices */
+	rc = xlink_reserved_memory_init(xlink_dev);
+	if (rc < 0) {
+		dev_err(&pdev->dev,
+			"Failed to set up reserved memory regions.\n");
+		goto r_cleanup;
+	}
+
+	/* allocate memory from the reserved memory regions */
+	rc = xlink_reserved_memory_alloc(xlink_dev);
+	if (rc < 0) {
+		dev_err(&pdev->dev,
+			"Failed to allocate reserved memory regions.\n");
+		goto r_cleanup;
+	}
+
+	/* init the xlink buffer pool used for rx/tx */
+	init_xlink_buf_pool(xlink_dev);
+
+	/* get reference to vpu ipc device */
+	rc = vpu_ipc_device_get(xlink_dev);
+	if (rc)
+		goto r_cleanup;
+
+	/* get device id */
+	rc = of_property_read_u32(dev->of_node, "intel,keembay-vpu-ipc-id",
+				  &xlink_dev->vpu_id);
+	if (rc) {
+		dev_err(dev, "Cannot get VPU ID from DT.\n");
+		goto r_cleanup;
+	}
+
+	/* assign a sw device id */
+	xlink_dev->sw_device_id = GET_SW_DEVICE_ID_FROM_VPU_ID
+			(xlink_dev->vpu_id);
+
+	/* assign a device name */
+	rc = of_property_read_string(dev->of_node, "intel,keembay-vpu-ipc-name",
+				     &xlink_dev->device_name);
+	if (rc) {
+		/* only warn for now; we will enforce this in the future */
+		dev_warn(dev, "VPU name not defined in DT, using %s as default.\n",
+			 VPU_DEVICE_NAME);
+		dev_warn(dev, "WARNING: additional VPU devices may fail probing.\n");
+		xlink_dev->device_name = VPU_DEVICE_NAME;
+	}
+
+	/* get platform data reference */
+	platform_set_drvdata(pdev, xlink_dev);
+
+	dev_info(dev, "Device id=%u sw_device_id=0x%x name=%s probe complete.\n",
+		 xlink_dev->vpu_id, xlink_dev->sw_device_id,
+			xlink_dev->device_name);
+	return 0;
+
+r_cleanup:
+	xlink_reserved_memory_remove(xlink_dev);
+	return rc;
+}
+
+static int keembay_xlink_ipc_remove(struct platform_device *pdev)
+{
+	struct xlink_ipc_dev *xlink_dev = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+
+	/*
+	 * no need to de-alloc xlink mem (local_xlink_mem and remote_xlink_mem)
+	 * since it was allocated with dmam_alloc
+	 */
+	xlink_reserved_memory_remove(xlink_dev);
+
+	/* release vpu ipc device */
+	vpu_ipc_device_put(xlink_dev);
+
+	dev_info(dev, "Keem Bay xlink IPC driver removed.\n");
+	return 0;
+}
+
+static const struct of_device_id keembay_xlink_ipc_of_match[] = {
+	{
+		.compatible = "intel,keembay-xlink-ipc",
+	},
+	{}
+};
+
+static struct platform_driver keembay_xlink_ipc_driver = {
+	.driver = {
+			.name = "keembay-xlink-ipc",
+			.of_match_table = keembay_xlink_ipc_of_match,
+		},
+	.probe = keembay_xlink_ipc_probe,
+	.remove = keembay_xlink_ipc_remove,
+};
+module_platform_driver(keembay_xlink_ipc_driver);
+
+MODULE_DESCRIPTION("Keem Bay xlink IPC Driver");
+MODULE_AUTHOR("Ryan Carnaghi <ryan.r.carnaghi@...el.com>");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/xlink-ipc.h b/include/linux/xlink-ipc.h
new file mode 100644
index 000000000000..f26b53bf6506
--- /dev/null
+++ b/include/linux/xlink-ipc.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*****************************************************************************
+ *
+ * Intel Keem Bay xlink IPC Driver
+ *
+ * Copyright (C) 2020 Intel Corporation
+ *
+ ****************************************************************************/
+
+#ifndef _XLINK_IPC_H_
+#define _XLINK_IPC_H_
+
+#include <linux/types.h>
+
+struct xlink_ipc_context {
+	u16 chan;
+	u8 is_volatile;
+};
+
+int xlink_ipc_connect(u32 sw_device_id);
+
+int xlink_ipc_write(u32 sw_device_id, void *data, size_t * const size,
+		    u32 timeout, void *context);
+
+int xlink_ipc_read(u32 sw_device_id, void *data, size_t * const size,
+		   u32 timeout, void *context);
+
+int xlink_ipc_get_device_list(u32 *sw_device_id_list, u32 *num_devices);
+
+int xlink_ipc_get_device_name(u32 sw_device_id, char *device_name,
+			      size_t name_size);
+
+int xlink_ipc_get_device_status(u32 sw_device_id, u32 *device_status);
+
+int xlink_ipc_boot_device(u32 sw_device_id, const char *binary_name);
+
+int xlink_ipc_reset_device(u32 sw_device_id);
+
+int xlink_ipc_open_channel(u32 sw_device_id, u32 channel);
+
+int xlink_ipc_close_channel(u32 sw_device_id, u32 channel);
+
+int xlink_ipc_register_for_events(u32 sw_device_id,
+				  int (*callback)(u32 sw_device_id, u32 event));
+
+int xlink_ipc_unregister_for_events(u32 sw_device_id);
+
+#endif /* _XLINK_IPC_H_ */
-- 
2.17.1

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