linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (c) 2015, Sony Mobile Communications AB.

 * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.

 */

​

#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/mailbox_client.h>

#include <linux/mfd/syscon.h>

#include <linux/module.h>

#include <linux/of_irq.h>

#include <linux/of_platform.h>

#include <linux/platform_device.h>

#include <linux/regmap.h>

#include <linux/sched.h>

#include <linux/sizes.h>

#include <linux/slab.h>

#include <linux/soc/qcom/smem.h>

#include <linux/wait.h>

#include <linux/rpmsg.h>

#include <linux/rpmsg/qcom_smd.h>

​

#include "rpmsg_internal.h"

​

/*

 * The Qualcomm Shared Memory communication solution provides point-to-point

 * channels for clients to send and receive streaming or packet based data.

 *

 * Each channel consists of a control item (channel info) and a ring buffer

 * pair. The channel info carry information related to channel state, flow

 * control and the offsets within the ring buffer.

 *

 * All allocated channels are listed in an allocation table, identifying the

 * pair of items by name, type and remote processor.

 *

 * Upon creating a new channel the remote processor allocates channel info and

 * ring buffer items from the smem heap and populate the allocation table. An

 * interrupt is sent to the other end of the channel and a scan for new

 * channels should be done. A channel never goes away, it will only change

 * state.

 *

 * The remote processor signals it intent for bring up the communication

 * channel by setting the state of its end of the channel to "opening" and

 * sends out an interrupt. We detect this change and register a smd device to

 * consume the channel. Upon finding a consumer we finish the handshake and the

 * channel is up.

 *

 * Upon closing a channel, the remote processor will update the state of its

 * end of the channel and signal us, we will then unregister any attached

 * device and close our end of the channel.

 *

 * Devices attached to a channel can use the qcom_smd_send function to push

 * data to the channel, this is done by copying the data into the tx ring

 * buffer, updating the pointers in the channel info and signaling the remote

 * processor.

 *

 * The remote processor does the equivalent when it transfer data and upon

 * receiving the interrupt we check the channel info for new data and delivers

 * this to the attached device. If the device is not ready to receive the data

 * we leave it in the ring buffer for now.

 */

​