[RFC PATCH 2/6] char: fastrpc: Add Qualcomm fastrpc basic driver model

[Srinivas Kandagatla]

This patch adds basic driver model for qualcomm fastrpc.
Each DSP rpmsg channel is represented as fastrpc channel context and
is exposed as a character driver for userspace interface.
Each compute context bank is represented as fastrpc-session-context,
which are dynamically managed by the channel context char device.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
 drivers/char/Kconfig   |  10 ++
 drivers/char/Makefile  |   1 +
 drivers/char/fastrpc.c | 337 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 348 insertions(+)
 create mode 100644 drivers/char/fastrpc.c

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 9d03b2ff5df6..75fd274c67df 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -552,6 +552,16 @@ config ADI
 	  and SSM (Silicon Secured Memory).  Intended consumers of this
 	  driver include crash and makedumpfile.
 
+config QCOM_FASTRPC
+	tristate "Qualcomm FastRPC"
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on RPMSG
+	help
+	  Provides a communication mechanism that allows for clients to
+	  make remote method invocations across processor boundary to
+	  applications DSP processor. Say M if you want to enable this
+	  module.
+
 endmenu
 
 config RANDOM_TRUST_CPU
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index b8d42b4e979b..30ec9187350e 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -58,3 +58,4 @@ js-rtc-y = rtc.o
 obj-$(CONFIG_XILLYBUS)		+= xillybus/
 obj-$(CONFIG_POWERNV_OP_PANEL)	+= powernv-op-panel.o
 obj-$(CONFIG_ADI)		+= adi.o
+obj-$(CONFIG_QCOM_FASTRPC)	+= fastrpc.o
diff --git a/drivers/char/fastrpc.c b/drivers/char/fastrpc.c
new file mode 100644
index 000000000000..97d8062eb3e1
--- /dev/null
+++ b/drivers/char/fastrpc.c
@@ -0,0 +1,337 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2011-2018, The Linux Foundation. All rights reserved.
+// Copyright (c) 2018, Linaro Limited
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/idr.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/rpmsg.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+
+#define ADSP_DOMAIN_ID (0)
+#define MDSP_DOMAIN_ID (1)
+#define SDSP_DOMAIN_ID (2)
+#define CDSP_DOMAIN_ID (3)
+#define FASTRPC_DEV_MAX		4 /* adsp, mdsp, slpi, cdsp*/
+#define FASTRPC_MAX_SESSIONS	9 /*8 compute, 1 cpz*/
+#define FASTRPC_CTX_MAX (256)
+#define FASTRPC_CTXID_MASK (0xFF0)
+#define FASTRPC_DEVICE_NAME	"fastrpc"
+
+#define cdev_to_cctx(d) container_of(d, struct fastrpc_channel_ctx, cdev)
+
+static const char *domains[FASTRPC_DEV_MAX] = { "adsp", "mdsp",
+						"sdsp", "cdsp"};
+static dev_t fastrpc_major;
+static struct class *fastrpc_class;
+
+struct fastrpc_session_ctx {
+	struct device *dev;
+	int sid;
+	bool used;
+	bool valid;
+	bool secure;
+};
+
+struct fastrpc_channel_ctx {
+	int domain_id;
+	int sesscount;
+	struct rpmsg_device *rpdev;
+	struct fastrpc_session_ctx session[FASTRPC_MAX_SESSIONS];
+	spinlock_t lock;
+	struct idr ctx_idr;
+	struct list_head users;
+	struct cdev cdev;
+	struct device dev;
+};
+
+struct fastrpc_user {
+	struct list_head user;
+	struct list_head maps;
+	struct list_head pending;
+
+	struct fastrpc_channel_ctx *cctx;
+	struct fastrpc_session_ctx *sctx;
+
+	int tgid;
+	int pd;
+	/* Lock for lists */
+	spinlock_t lock;
+	/* lock for allocations */
+	struct mutex mutex;
+	struct device *dev;
+};
+
+static const struct of_device_id fastrpc_match_table[] = {
+	{ .compatible = "qcom,fastrpc-compute-cb", },
+	{}
+};
+
+static int fastrpc_device_release(struct inode *inode, struct file *file)
+{
+	struct fastrpc_user *fl = (struct fastrpc_user *)file->private_data;
+	struct fastrpc_channel_ctx *cctx = cdev_to_cctx(inode->i_cdev);
+
+	spin_lock(&cctx->lock);
+	list_del(&fl->user);
+	spin_unlock(&cctx->lock);
+
+	kfree(fl);
+	file->private_data = NULL;
+
+	return 0;
+}
+
+static int fastrpc_device_open(struct inode *inode, struct file *filp)
+{
+	struct fastrpc_channel_ctx *cctx = cdev_to_cctx(inode->i_cdev);
+	struct fastrpc_user *fl = NULL;
+
+	fl = kzalloc(sizeof(*fl), GFP_KERNEL);
+	if (!fl)
+		return -ENOMEM;
+
+	filp->private_data = fl;
+
+	spin_lock_init(&fl->lock);
+	mutex_init(&fl->mutex);
+	INIT_LIST_HEAD(&fl->pending);
+	INIT_LIST_HEAD(&fl->maps);
+	INIT_LIST_HEAD(&fl->user);
+
+	fl->tgid = current->tgid;
+	fl->cctx = cctx;
+	fl->dev = &cctx->rpdev->dev;
+	spin_lock(&cctx->lock);
+	list_add_tail(&fl->user, &cctx->users);
+	spin_unlock(&cctx->lock);
+
+	return 0;
+}
+
+static const struct file_operations fastrpc_fops = {
+	.open = fastrpc_device_open,
+	.release = fastrpc_device_release,
+};
+
+static int fastrpc_cb_probe(struct platform_device *pdev)
+{
+	struct fastrpc_channel_ctx *cctx;
+	struct fastrpc_session_ctx *sess;
+	struct device *dev = &pdev->dev;
+	int i, sessions = 0;
+
+	cctx = dev_get_drvdata(dev->parent);
+	if (!cctx)
+		return -EINVAL;
+
+	of_property_read_u32(dev->of_node, "nsessions", &sessions);
+
+	spin_lock(&cctx->lock);
+	sess = &cctx->session[cctx->sesscount];
+	sess->used = false;
+	sess->valid = true;
+	sess->dev = dev;
+	dev_set_drvdata(dev, sess);
+	sess->secure = of_property_read_bool(dev->of_node, "secured");
+
+	if (of_property_read_u32(dev->of_node, "reg", &sess->sid))
+		dev_err(dev, "FastRPC Session ID not specified in DT\n");
+
+	if (sessions > 0) {
+		struct fastrpc_session_ctx *dup_sess;
+
+		for (i = 1; i < sessions; i++) {
+			if (cctx->sesscount++ >= FASTRPC_MAX_SESSIONS)
+				break;
+			dup_sess = &cctx->session[cctx->sesscount];
+			memcpy(dup_sess, sess, sizeof(*dup_sess));
+		}
+	}
+	cctx->sesscount++;
+	spin_unlock(&cctx->lock);
+	dma_set_mask(dev, DMA_BIT_MASK(32));
+
+	return 0;
+}
+
+static int fastrpc_cb_remove(struct platform_device *pdev)
+{
+	struct fastrpc_channel_ctx *cctx = dev_get_drvdata(pdev->dev.parent);
+	struct fastrpc_session_ctx *sess = dev_get_drvdata(&pdev->dev);
+	int i;
+
+	spin_lock(&cctx->lock);
+	for (i = 1; i < FASTRPC_MAX_SESSIONS; i++) {
+		if (cctx->session[i].sid == sess->sid) {
+			cctx->session[i].valid = false;
+			cctx->sesscount--;
+		}
+	}
+	spin_unlock(&cctx->lock);
+
+	return 0;
+}
+
+static struct platform_driver fastrpc_cb_driver = {
+	.probe = fastrpc_cb_probe,
+	.remove = fastrpc_cb_remove,
+	.driver = {
+		.name = "fastrpc",
+		.owner = THIS_MODULE,
+		.of_match_table = fastrpc_match_table,
+		.suppress_bind_attrs = true,
+	},
+};
+
+static void fastrpc_cdev_release_device(struct device *dev)
+{
+	struct fastrpc_channel_ctx *data = dev_get_drvdata(dev->parent);
+
+	cdev_del(&data->cdev);
+}
+
+static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
+{
+	struct device *rdev = &rpdev->dev;
+	struct fastrpc_channel_ctx *data;
+	struct device *dev;
+	int err, domain_id;
+
+	data = devm_kzalloc(rdev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	err = of_property_read_u32(rdev->of_node, "reg", &domain_id);
+	if (err) {
+		dev_err(rdev, "FastRPC Domain ID not specified in DT\n");
+		return err;
+	}
+
+	if (domain_id > CDSP_DOMAIN_ID) {
+		dev_err(rdev, "FastRPC Invalid Domain ID %d\n", domain_id);
+		return -EINVAL;
+	}
+
+	dev = &data->dev;
+	device_initialize(dev);
+	dev->parent = &rpdev->dev;
+	dev->class = fastrpc_class;
+
+	cdev_init(&data->cdev, &fastrpc_fops);
+	data->cdev.owner = THIS_MODULE;
+	dev->devt = MKDEV(MAJOR(fastrpc_major), domain_id);
+	dev->id = domain_id;
+	dev_set_name(&data->dev, "fastrpc-%s", domains[domain_id]);
+	dev->release = fastrpc_cdev_release_device;
+
+	err = cdev_device_add(&data->cdev, &data->dev);
+	if (err)
+		goto cdev_err;
+
+	dev_set_drvdata(&rpdev->dev, data);
+	dma_set_mask_and_coherent(rdev, DMA_BIT_MASK(32));
+	INIT_LIST_HEAD(&data->users);
+	spin_lock_init(&data->lock);
+	idr_init(&data->ctx_idr);
+	data->domain_id = domain_id;
+	data->rpdev = rpdev;
+
+	return of_platform_populate(rdev->of_node, NULL, NULL, rdev);
+
+cdev_err:
+	put_device(dev);
+	return err;
+}
+
+static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
+{
+	struct fastrpc_channel_ctx *cctx = dev_get_drvdata(&rpdev->dev);
+
+	device_del(&cctx->dev);
+	put_device(&cctx->dev);
+	of_platform_depopulate(&rpdev->dev);
+	kfree(cctx);
+}
+
+static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
+				  int len, void *priv, u32 addr)
+{
+	return 0;
+}
+
+static const struct of_device_id fastrpc_rpmsg_of_match[] = {
+	{ .compatible = "qcom,fastrpc" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, fastrpc_rpmsg_of_match);
+
+static struct rpmsg_driver fastrpc_driver = {
+	.probe = fastrpc_rpmsg_probe,
+	.remove = fastrpc_rpmsg_remove,
+	.callback = fastrpc_rpmsg_callback,
+	.drv = {
+		.name = "qcom,msm_fastrpc_rpmsg",
+		.of_match_table = fastrpc_rpmsg_of_match,
+	},
+};
+
+static int fastrpc_init(void)
+{
+	int ret;
+
+	ret = alloc_chrdev_region(&fastrpc_major, 0, FASTRPC_DEV_MAX,
+				  FASTRPC_DEVICE_NAME);
+	if (ret < 0) {
+		pr_err("fastrpc: failed to allocate char dev region\n");
+		return ret;
+	}
+
+	fastrpc_class = class_create(THIS_MODULE, "fastrpc");
+	if (IS_ERR(fastrpc_class)) {
+		pr_err("failed to create rpmsg class\n");
+		ret = PTR_ERR(fastrpc_class);
+		goto err_class;
+	}
+
+	ret = platform_driver_register(&fastrpc_cb_driver);
+	if (ret < 0) {
+		pr_err("fastrpc: failed to register cb driver\n");
+		goto err_pdev;
+	}
+
+	ret = register_rpmsg_driver(&fastrpc_driver);
+	if (ret < 0) {
+		pr_err("fastrpc: failed to register rpmsg driver\n");
+		goto err_rpdrv;
+	}
+
+	return 0;
+err_rpdrv:
+	platform_driver_unregister(&fastrpc_cb_driver);
+err_pdev:
+	class_destroy(fastrpc_class);
+err_class:
+	unregister_chrdev_region(fastrpc_major, FASTRPC_DEV_MAX);
+	return ret;
+}
+module_init(fastrpc_init);
+
+static void fastrpc_exit(void)
+{
+	platform_driver_unregister(&fastrpc_cb_driver);
+	unregister_rpmsg_driver(&fastrpc_driver);
+	class_destroy(fastrpc_class);
+	unregister_chrdev_region(fastrpc_major, FASTRPC_DEV_MAX);
+}
+module_exit(fastrpc_exit);
+
+MODULE_ALIAS("fastrpc:fastrpc");
+MODULE_LICENSE("GPL v2");
-- 
2.19.2