// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2021, Linaro Ltd <[email protected]> */
#include <linux/kernel.h>
#include <linux/mhi.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/wwan.h>
/* MHI wwan flags */
enum mhi_wwan_flags {
MHI_WWAN_DL_CAP,
MHI_WWAN_UL_CAP,
MHI_WWAN_RX_REFILL,
};
#define MHI_WWAN_MAX_MTU 0x8000
struct mhi_wwan_dev {
/* Lower level is a mhi dev, upper level is a wwan port */
struct mhi_device *mhi_dev;
struct wwan_port *wwan_port;
/* State and capabilities */
unsigned long flags;
size_t mtu;
/* Protect against concurrent TX and TX-completion (bh) */
spinlock_t tx_lock;
/* Protect RX budget and rx_refill scheduling */
spinlock_t rx_lock;
struct work_struct rx_refill;
/* RX budget is initially set to the size of the MHI RX queue and is
* used to limit the number of allocated and queued packets. It is
* decremented on data queueing and incremented on data release.
*/
unsigned int rx_budget;
};
/* Increment RX budget and schedule RX refill if necessary */
static void mhi_wwan_rx_budget_inc(struct mhi_wwan_dev *mhiwwan)
{
spin_lock_bh(&mhiwwan->rx_lock);
mhiwwan->rx_budget++;
if (test_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags))
schedule_work(&mhiwwan->rx_refill);
spin_unlock_bh(&mhiwwan->rx_lock);
}
/* Decrement RX budget if non-zero and return true on success */
static bool mhi_wwan_rx_budget_dec(struct mhi_wwan_dev *mhiwwan)
{
bool ret = false;
spin_lock_bh(&mhiwwan->rx_lock);
if (mhiwwan->rx_budget) {
mhiwwan->rx_budget--;
if (test_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags))
ret = true;
}
spin_unlock_bh(&mhiwwan->rx_lock);
return ret;
}
static void __mhi_skb_destructor(struct sk_buff *skb)
{
/* RX buffer has been consumed, increase the allowed budget */
mhi_wwan_rx_budget_inc(skb_shinfo(skb)->destructor_arg);
}
static void mhi_wwan_ctrl_refill_work(struct work_struct *work)
{
struct mhi_wwan_dev *mhiwwan = container_of(work, struct mhi_wwan_dev, rx_refill);
struct mhi_device *mhi_dev = mhiwwan->mhi_dev;
while (mhi_wwan_rx_budget_dec(mhiwwan)) {
struct sk_buff *skb;
skb = alloc_skb(mhiwwan->mtu, GFP_KERNEL);
if (!skb) {
mhi_wwan_rx_budget_inc(mhiwwan);
break;
}
/* To prevent unlimited buffer allocation if nothing consumes
* the RX buffers (passed to WWAN core), track their lifespan
* to not allocate more than allowed budget.
*/
skb->destructor = __mhi_skb_destructor;
skb_shinfo(skb)->destructor_arg = mhiwwan;
if (mhi_queue_skb(mhi_dev, DMA_FROM_DEVICE, skb, mhiwwan->mtu, MHI_EOT)) {
dev_err(&mhi_dev->dev, "Failed to queue buffer\n");
kfree_skb(skb);
break;
}
}
}
static int mhi_wwan_ctrl_start(struct wwan_port *port)
{
struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port);
int ret;
/* Start mhi device's channel(s) */
ret = mhi_prepare_for_transfer(mhiwwan->mhi_dev);
if (ret)
return ret;
/* Don't allocate more buffers than MHI channel queue size */
mhiwwan->rx_budget = mhi_get_free_desc_count(mhiwwan->mhi_dev, DMA_FROM_DEVICE);
/* Add buffers to the MHI inbound queue */
if (test_bit(MHI_WWAN_DL_CAP, &mhiwwan->flags)) {
set_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags);
mhi_wwan_ctrl_refill_work(&mhiwwan->rx_refill);
}
return 0;
}
static void mhi_wwan_ctrl_stop(struct wwan_port *port)
{
struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port);
spin_lock_bh(&mhiwwan->rx_lock);
clear_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags);
spin_unlock_bh(&mhiwwan->rx_lock);
cancel_work_sync(&mhiwwan->rx_refill);
mhi_unprepare_from_transfer(mhiwwan->mhi_dev);
}
static int mhi_wwan_ctrl_tx(struct wwan_port *port, struct sk_buff *skb)
{
struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port);
int ret;
if (skb->len > mhiwwan->mtu)
return -EMSGSIZE;
if (!test_bit(MHI_WWAN_UL_CAP, &mhiwwan->flags))
return -EOPNOTSUPP;
/* Queue the packet for MHI transfer and check fullness of the queue */
spin_lock_bh(&mhiwwan->tx_lock);
ret = mhi_queue_skb(mhiwwan->mhi_dev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
if (mhi_queue_is_full(mhiwwan->mhi_dev, DMA_TO_DEVICE))
wwan_port_txoff(port);
spin_unlock_bh(&mhiwwan->tx_lock);
return ret;
}
static const struct wwan_port_ops wwan_pops = {
.start = mhi_wwan_ctrl_start,
.stop = mhi_wwan_ctrl_stop,
.tx = mhi_wwan_ctrl_tx,
};
static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev,
struct mhi_result *mhi_result)
{
struct mhi_wwan_dev *mhiwwan = dev_get_drvdata(&mhi_dev->dev);
struct wwan_port *port = mhiwwan->wwan_port;
struct sk_buff *skb = mhi_result->buf_addr;
dev_dbg(&mhi_dev->dev, "%s: status: %d xfer_len: %zu\n", __func__,
mhi_result->transaction_status, mhi_result->bytes_xferd);
/* MHI core has done with the buffer, release it */
consume_skb(skb);
/* There is likely new slot available in the MHI queue, re-allow TX */
spin_lock_bh(&mhiwwan->tx_lock);
if (!mhi_queue_is_full(mhiwwan->mhi_dev, DMA_TO_DEVICE))
wwan_port_txon(port);
spin_unlock_bh(&mhiwwan->tx_lock);
}
static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev,
struct mhi_result *mhi_result)
{
struct mhi_wwan_dev *mhiwwan = dev_get_drvdata(&mhi_dev->dev);
struct wwan_port *port = mhiwwan->wwan_port;
struct sk_buff *skb = mhi_result->buf_addr;
dev_dbg(&mhi_dev->dev, "%s: status: %d receive_len: %zu\n", __func__,
mhi_result->transaction_status, mhi_result->bytes_xferd);
if (mhi_result->transaction_status &&
mhi_result->transaction_status != -EOVERFLOW) {
kfree_skb(skb);
return;
}
/* MHI core does not update skb->len, do it before forward */
skb_put(skb, mhi_result->bytes_xferd);
wwan_port_rx(port, skb);
/* Do not increment rx budget nor refill RX buffers now, wait for the
* buffer to be consumed. Done from __mhi_skb_destructor().
*/
}
static int mhi_wwan_ctrl_probe(struct mhi_device *mhi_dev,
const struct mhi_device_id *id)
{
struct mhi_controller *cntrl = mhi_dev->mhi_cntrl;
struct mhi_wwan_dev *mhiwwan;
struct wwan_port *port;
mhiwwan = kzalloc(sizeof(*mhiwwan), GFP_KERNEL);
if (!mhiwwan)
return -ENOMEM;
mhiwwan->mhi_dev = mhi_dev;
mhiwwan->mtu = MHI_WWAN_MAX_MTU;
INIT_WORK(&mhiwwan->rx_refill, mhi_wwan_ctrl_refill_work);
spin_lock_init(&mhiwwan->tx_lock);
spin_lock_init(&mhiwwan->rx_lock);
if (mhi_dev->dl_chan)
set_bit(MHI_WWAN_DL_CAP, &mhiwwan->flags);
if (mhi_dev->ul_chan)
set_bit(MHI_WWAN_UL_CAP, &mhiwwan->flags);
dev_set_drvdata(&mhi_dev->dev, mhiwwan);
/* Register as a wwan port, id->driver_data contains wwan port type */
port = wwan_create_port(&cntrl->mhi_dev->dev, id->driver_data,
&wwan_pops, NULL, mhiwwan);
if (IS_ERR(port)) {
kfree(mhiwwan);
return PTR_ERR(port);
}
mhiwwan->wwan_port = port;
return 0;
};
static void mhi_wwan_ctrl_remove(struct mhi_device *mhi_dev)
{
struct mhi_wwan_dev *mhiwwan = dev_get_drvdata(&mhi_dev->dev);
wwan_remove_port(mhiwwan->wwan_port);
kfree(mhiwwan);
}
static const struct mhi_device_id mhi_wwan_ctrl_match_table[] = {
{ .chan = "DUN", .driver_data = WWAN_PORT_AT },
{ .chan = "DUN2", .driver_data = WWAN_PORT_AT },
{ .chan = "MBIM", .driver_data = WWAN_PORT_MBIM },
{ .chan = "QMI", .driver_data = WWAN_PORT_QMI },
{ .chan = "DIAG", .driver_data = WWAN_PORT_QCDM },
{ .chan = "FIREHOSE", .driver_data = WWAN_PORT_FIREHOSE },
{},
};
MODULE_DEVICE_TABLE(mhi, mhi_wwan_ctrl_match_table);
static struct mhi_driver mhi_wwan_ctrl_driver = {
.id_table = mhi_wwan_ctrl_match_table,
.remove = mhi_wwan_ctrl_remove,
.probe = mhi_wwan_ctrl_probe,
.ul_xfer_cb = mhi_ul_xfer_cb,
.dl_xfer_cb = mhi_dl_xfer_cb,
.driver = {
.name = "mhi_wwan_ctrl",
},
};
module_mhi_driver(mhi_wwan_ctrl_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MHI WWAN CTRL Driver");
MODULE_AUTHOR("Loic Poulain <[email protected]>");
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