root/drivers/rpmsg/qcom_glink_smem.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2016, Linaro Ltd
 */

#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/mailbox_client.h>
#include <linux/mfd/syscon.h>
#include <linux/slab.h>
#include <linux/rpmsg.h>
#include <linux/idr.h>
#include <linux/circ_buf.h>
#include <linux/soc/qcom/smem.h>
#include <linux/sizes.h>
#include <linux/delay.h>
#include <linux/regmap.h>
#include <linux/workqueue.h>
#include <linux/list.h>

#include <linux/rpmsg/qcom_glink.h>

#include "qcom_glink_native.h"

#define FIFO_FULL_RESERVE 8
#define FIFO_ALIGNMENT 8
#define TX_BLOCKED_CMD_RESERVE 8 /* size of struct read_notif_request */

#define SMEM_GLINK_NATIVE_XPRT_DESCRIPTOR       478
#define SMEM_GLINK_NATIVE_XPRT_FIFO_0           479
#define SMEM_GLINK_NATIVE_XPRT_FIFO_1           480

struct qcom_glink_smem {
        struct device dev;

        int irq;
        struct qcom_glink *glink;

        struct mbox_client mbox_client;
        struct mbox_chan *mbox_chan;

        u32 remote_pid;
};

struct glink_smem_pipe {
        struct qcom_glink_pipe native;

        __le32 *tail;
        __le32 *head;

        void *fifo;

        struct qcom_glink_smem *smem;
};

#define to_smem_pipe(p) container_of(p, struct glink_smem_pipe, native)

static size_t glink_smem_rx_avail(struct qcom_glink_pipe *np)
{
        struct glink_smem_pipe *pipe = to_smem_pipe(np);
        struct qcom_glink_smem *smem = pipe->smem;
        size_t len;
        void *fifo;
        u32 head;
        u32 tail;

        if (!pipe->fifo) {
                fifo = qcom_smem_get(smem->remote_pid,
                                     SMEM_GLINK_NATIVE_XPRT_FIFO_1, &len);
                if (IS_ERR(fifo)) {
                        pr_err("failed to acquire RX fifo handle: %ld\n",
                               PTR_ERR(fifo));
                        return 0;
                }

                pipe->fifo = fifo;
                pipe->native.length = len;
        }

        head = le32_to_cpu(*pipe->head);
        tail = le32_to_cpu(*pipe->tail);

        if (head < tail)
                return pipe->native.length - tail + head;
        else
                return head - tail;
}

static void glink_smem_rx_peek(struct qcom_glink_pipe *np,
                               void *data, unsigned int offset, size_t count)
{
        struct glink_smem_pipe *pipe = to_smem_pipe(np);
        size_t len;
        u32 tail;

        tail = le32_to_cpu(*pipe->tail);
        tail += offset;
        if (tail >= pipe->native.length)
                tail -= pipe->native.length;

        len = min_t(size_t, count, pipe->native.length - tail);
        if (len)
                memcpy_fromio(data, pipe->fifo + tail, len);

        if (len != count)
                memcpy_fromio(data + len, pipe->fifo, (count - len));
}

static void glink_smem_rx_advance(struct qcom_glink_pipe *np,
                                  size_t count)
{
        struct glink_smem_pipe *pipe = to_smem_pipe(np);
        u32 tail;

        tail = le32_to_cpu(*pipe->tail);

        tail += count;
        if (tail >= pipe->native.length)
                tail -= pipe->native.length;

        *pipe->tail = cpu_to_le32(tail);
}

static size_t glink_smem_tx_avail(struct qcom_glink_pipe *np)
{
        struct glink_smem_pipe *pipe = to_smem_pipe(np);
        u32 head;
        u32 tail;
        u32 avail;

        head = le32_to_cpu(*pipe->head);
        tail = le32_to_cpu(*pipe->tail);

        if (tail <= head)
                avail = pipe->native.length - head + tail;
        else
                avail = tail - head;

        if (avail < (FIFO_FULL_RESERVE + TX_BLOCKED_CMD_RESERVE))
                avail = 0;
        else
                avail -= FIFO_FULL_RESERVE + TX_BLOCKED_CMD_RESERVE;

        return avail;
}

static unsigned int glink_smem_tx_write_one(struct glink_smem_pipe *pipe,
                                            unsigned int head,
                                            const void *data, size_t count)
{
        size_t len;

        len = min_t(size_t, count, pipe->native.length - head);
        if (len)
                memcpy(pipe->fifo + head, data, len);

        if (len != count)
                memcpy(pipe->fifo, data + len, count - len);

        head += count;
        if (head >= pipe->native.length)
                head -= pipe->native.length;

        return head;
}

static void glink_smem_tx_write(struct qcom_glink_pipe *glink_pipe,
                                const void *hdr, size_t hlen,
                                const void *data, size_t dlen)
{
        struct glink_smem_pipe *pipe = to_smem_pipe(glink_pipe);
        unsigned int head;

        head = le32_to_cpu(*pipe->head);

        head = glink_smem_tx_write_one(pipe, head, hdr, hlen);
        head = glink_smem_tx_write_one(pipe, head, data, dlen);

        /* Ensure head is always aligned to 8 bytes */
        head = ALIGN(head, 8);
        if (head >= pipe->native.length)
                head -= pipe->native.length;

        /* Ensure ordering of fifo and head update */
        wmb();

        *pipe->head = cpu_to_le32(head);
}

static void glink_smem_tx_kick(struct qcom_glink_pipe *glink_pipe)
{
        struct glink_smem_pipe *pipe = to_smem_pipe(glink_pipe);
        struct qcom_glink_smem *smem = pipe->smem;

        mbox_send_message(smem->mbox_chan, NULL);
        mbox_client_txdone(smem->mbox_chan, 0);
}

static irqreturn_t qcom_glink_smem_intr(int irq, void *data)
{
        struct qcom_glink_smem *smem = data;

        qcom_glink_native_rx(smem->glink);

        return IRQ_HANDLED;
}

static void qcom_glink_smem_release(struct device *dev)
{
        struct qcom_glink_smem *smem = container_of(dev, struct qcom_glink_smem, dev);

        kfree(smem);
}

struct qcom_glink_smem *qcom_glink_smem_register(struct device *parent,
                                                 struct device_node *node)
{
        struct glink_smem_pipe *rx_pipe;
        struct glink_smem_pipe *tx_pipe;
        struct qcom_glink_smem *smem;
        struct qcom_glink *glink;
        struct device *dev;
        u32 remote_pid;
        __le32 *descs;
        size_t size;
        int ret;

        smem = kzalloc_obj(*smem);
        if (!smem)
                return ERR_PTR(-ENOMEM);

        dev = &smem->dev;

        dev->parent = parent;
        dev->of_node = node;
        dev->release = qcom_glink_smem_release;
        dev_set_name(dev, "%s:%pOFn", dev_name(parent->parent), node);
        ret = device_register(dev);
        if (ret) {
                pr_err("failed to register glink edge\n");
                put_device(dev);
                return ERR_PTR(ret);
        }

        ret = of_property_read_u32(dev->of_node, "qcom,remote-pid",
                                   &remote_pid);
        if (ret) {
                dev_err(dev, "failed to parse qcom,remote-pid\n");
                goto err_put_dev;
        }

        smem->remote_pid = remote_pid;

        rx_pipe = devm_kzalloc(dev, sizeof(*rx_pipe), GFP_KERNEL);
        tx_pipe = devm_kzalloc(dev, sizeof(*tx_pipe), GFP_KERNEL);
        if (!rx_pipe || !tx_pipe) {
                ret = -ENOMEM;
                goto err_put_dev;
        }

        ret = qcom_smem_alloc(remote_pid,
                              SMEM_GLINK_NATIVE_XPRT_DESCRIPTOR, 32);
        if (ret && ret != -EEXIST) {
                dev_err(dev, "failed to allocate glink descriptors\n");
                goto err_put_dev;
        }

        descs = qcom_smem_get(remote_pid,
                              SMEM_GLINK_NATIVE_XPRT_DESCRIPTOR, &size);
        if (IS_ERR(descs)) {
                dev_err(dev, "failed to acquire xprt descriptor\n");
                ret = PTR_ERR(descs);
                goto err_put_dev;
        }

        if (size != 32) {
                dev_err(dev, "glink descriptor of invalid size\n");
                ret = -EINVAL;
                goto err_put_dev;
        }

        tx_pipe->tail = &descs[0];
        tx_pipe->head = &descs[1];
        rx_pipe->tail = &descs[2];
        rx_pipe->head = &descs[3];

        ret = qcom_smem_alloc(remote_pid, SMEM_GLINK_NATIVE_XPRT_FIFO_0,
                              SZ_16K);
        if (ret && ret != -EEXIST) {
                dev_err(dev, "failed to allocate TX fifo\n");
                goto err_put_dev;
        }

        tx_pipe->fifo = qcom_smem_get(remote_pid, SMEM_GLINK_NATIVE_XPRT_FIFO_0,
                                      &tx_pipe->native.length);
        if (IS_ERR(tx_pipe->fifo)) {
                dev_err(dev, "failed to acquire TX fifo\n");
                ret = PTR_ERR(tx_pipe->fifo);
                goto err_put_dev;
        }

        smem->irq = of_irq_get(smem->dev.of_node, 0);
        ret = devm_request_irq(&smem->dev, smem->irq, qcom_glink_smem_intr,
                               IRQF_NO_SUSPEND | IRQF_NO_AUTOEN,
                               "glink-smem", smem);
        if (ret) {
                dev_err(&smem->dev, "failed to request IRQ\n");
                goto err_put_dev;
        }

        smem->mbox_client.dev = &smem->dev;
        smem->mbox_client.knows_txdone = true;
        smem->mbox_chan = mbox_request_channel(&smem->mbox_client, 0);
        if (IS_ERR(smem->mbox_chan)) {
                ret = dev_err_probe(&smem->dev, PTR_ERR(smem->mbox_chan),
                                    "failed to acquire IPC channel\n");
                goto err_put_dev;
        }

        rx_pipe->smem = smem;
        rx_pipe->native.avail = glink_smem_rx_avail;
        rx_pipe->native.peek = glink_smem_rx_peek;
        rx_pipe->native.advance = glink_smem_rx_advance;

        tx_pipe->smem = smem;
        tx_pipe->native.avail = glink_smem_tx_avail;
        tx_pipe->native.write = glink_smem_tx_write;
        tx_pipe->native.kick = glink_smem_tx_kick;

        *rx_pipe->tail = 0;
        *tx_pipe->head = 0;

        glink = qcom_glink_native_probe(dev,
                                        GLINK_FEATURE_INTENT_REUSE,
                                        &rx_pipe->native, &tx_pipe->native,
                                        false);
        if (IS_ERR(glink)) {
                ret = PTR_ERR(glink);
                goto err_free_mbox;
        }

        smem->glink = glink;

        enable_irq(smem->irq);

        return smem;

err_free_mbox:
        mbox_free_channel(smem->mbox_chan);

err_put_dev:
        device_unregister(dev);

        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(qcom_glink_smem_register);

void qcom_glink_smem_unregister(struct qcom_glink_smem *smem)
{
        struct qcom_glink *glink = smem->glink;

        disable_irq(smem->irq);

        qcom_glink_native_remove(glink);

        mbox_free_channel(smem->mbox_chan);
        device_unregister(&smem->dev);
}
EXPORT_SYMBOL_GPL(qcom_glink_smem_unregister);

MODULE_AUTHOR("Bjorn Andersson <bjorn.andersson@linaro.org>");
MODULE_DESCRIPTION("Qualcomm GLINK SMEM driver");
MODULE_LICENSE("GPL v2");