linux/drivers/mailbox/mailbox.c
Jassi Brar c7dacf5b0f mailbox: avoid timer start from callback
If the txdone is done by polling, it is possible for msg_submit() to start
the timer while txdone_hrtimer() callback is running. If the timer needs
recheduling, it could already be enqueued by the time hrtimer_forward_now()
is called, leading hrtimer to loudly complain.

WARNING: CPU: 3 PID: 74 at kernel/time/hrtimer.c:932 hrtimer_forward+0xc4/0x110
CPU: 3 PID: 74 Comm: kworker/u8:1 Not tainted 5.9.0-rc2-00236-gd3520067d01c-dirty #5
Hardware name: Libre Computer AML-S805X-AC (DT)
Workqueue: events_freezable_power_ thermal_zone_device_check
pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--)
pc : hrtimer_forward+0xc4/0x110
lr : txdone_hrtimer+0xf8/0x118
[...]

This can be fixed by not starting the timer from the callback path. Which
requires the timer reloading as long as any message is queued on the
channel, and not just when current tx is not done yet.

Fixes: 0cc67945ea ("mailbox: switch to hrtimer for tx_complete polling")
Reported-by: Da Xue <da@libre.computer>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
2020-10-16 19:09:17 -05:00

619 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Mailbox: Common code for Mailbox controllers and users
*
* Copyright (C) 2013-2014 Linaro Ltd.
* Author: Jassi Brar <jassisinghbrar@gmail.com>
*/
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/bitops.h>
#include <linux/mailbox_client.h>
#include <linux/mailbox_controller.h>
#include "mailbox.h"
static LIST_HEAD(mbox_cons);
static DEFINE_MUTEX(con_mutex);
static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
{
int idx;
unsigned long flags;
spin_lock_irqsave(&chan->lock, flags);
/* See if there is any space left */
if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
spin_unlock_irqrestore(&chan->lock, flags);
return -ENOBUFS;
}
idx = chan->msg_free;
chan->msg_data[idx] = mssg;
chan->msg_count++;
if (idx == MBOX_TX_QUEUE_LEN - 1)
chan->msg_free = 0;
else
chan->msg_free++;
spin_unlock_irqrestore(&chan->lock, flags);
return idx;
}
static void msg_submit(struct mbox_chan *chan)
{
unsigned count, idx;
unsigned long flags;
void *data;
int err = -EBUSY;
spin_lock_irqsave(&chan->lock, flags);
if (!chan->msg_count || chan->active_req)
goto exit;
count = chan->msg_count;
idx = chan->msg_free;
if (idx >= count)
idx -= count;
else
idx += MBOX_TX_QUEUE_LEN - count;
data = chan->msg_data[idx];
if (chan->cl->tx_prepare)
chan->cl->tx_prepare(chan->cl, data);
/* Try to submit a message to the MBOX controller */
err = chan->mbox->ops->send_data(chan, data);
if (!err) {
chan->active_req = data;
chan->msg_count--;
}
exit:
spin_unlock_irqrestore(&chan->lock, flags);
/* kick start the timer immediately to avoid delays */
if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
/* but only if not already active */
if (!hrtimer_active(&chan->mbox->poll_hrt))
hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
}
}
static void tx_tick(struct mbox_chan *chan, int r)
{
unsigned long flags;
void *mssg;
spin_lock_irqsave(&chan->lock, flags);
mssg = chan->active_req;
chan->active_req = NULL;
spin_unlock_irqrestore(&chan->lock, flags);
/* Submit next message */
msg_submit(chan);
if (!mssg)
return;
/* Notify the client */
if (chan->cl->tx_done)
chan->cl->tx_done(chan->cl, mssg, r);
if (r != -ETIME && chan->cl->tx_block)
complete(&chan->tx_complete);
}
static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
{
struct mbox_controller *mbox =
container_of(hrtimer, struct mbox_controller, poll_hrt);
bool txdone, resched = false;
int i;
for (i = 0; i < mbox->num_chans; i++) {
struct mbox_chan *chan = &mbox->chans[i];
if (chan->active_req && chan->cl) {
resched = true;
txdone = chan->mbox->ops->last_tx_done(chan);
if (txdone)
tx_tick(chan, 0);
}
}
if (resched) {
hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period));
return HRTIMER_RESTART;
}
return HRTIMER_NORESTART;
}
/**
* mbox_chan_received_data - A way for controller driver to push data
* received from remote to the upper layer.
* @chan: Pointer to the mailbox channel on which RX happened.
* @mssg: Client specific message typecasted as void *
*
* After startup and before shutdown any data received on the chan
* is passed on to the API via atomic mbox_chan_received_data().
* The controller should ACK the RX only after this call returns.
*/
void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
{
/* No buffering the received data */
if (chan->cl->rx_callback)
chan->cl->rx_callback(chan->cl, mssg);
}
EXPORT_SYMBOL_GPL(mbox_chan_received_data);
/**
* mbox_chan_txdone - A way for controller driver to notify the
* framework that the last TX has completed.
* @chan: Pointer to the mailbox chan on which TX happened.
* @r: Status of last TX - OK or ERROR
*
* The controller that has IRQ for TX ACK calls this atomic API
* to tick the TX state machine. It works only if txdone_irq
* is set by the controller.
*/
void mbox_chan_txdone(struct mbox_chan *chan, int r)
{
if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
dev_err(chan->mbox->dev,
"Controller can't run the TX ticker\n");
return;
}
tx_tick(chan, r);
}
EXPORT_SYMBOL_GPL(mbox_chan_txdone);
/**
* mbox_client_txdone - The way for a client to run the TX state machine.
* @chan: Mailbox channel assigned to this client.
* @r: Success status of last transmission.
*
* The client/protocol had received some 'ACK' packet and it notifies
* the API that the last packet was sent successfully. This only works
* if the controller can't sense TX-Done.
*/
void mbox_client_txdone(struct mbox_chan *chan, int r)
{
if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
return;
}
tx_tick(chan, r);
}
EXPORT_SYMBOL_GPL(mbox_client_txdone);
/**
* mbox_client_peek_data - A way for client driver to pull data
* received from remote by the controller.
* @chan: Mailbox channel assigned to this client.
*
* A poke to controller driver for any received data.
* The data is actually passed onto client via the
* mbox_chan_received_data()
* The call can be made from atomic context, so the controller's
* implementation of peek_data() must not sleep.
*
* Return: True, if controller has, and is going to push after this,
* some data.
* False, if controller doesn't have any data to be read.
*/
bool mbox_client_peek_data(struct mbox_chan *chan)
{
if (chan->mbox->ops->peek_data)
return chan->mbox->ops->peek_data(chan);
return false;
}
EXPORT_SYMBOL_GPL(mbox_client_peek_data);
/**
* mbox_send_message - For client to submit a message to be
* sent to the remote.
* @chan: Mailbox channel assigned to this client.
* @mssg: Client specific message typecasted.
*
* For client to submit data to the controller destined for a remote
* processor. If the client had set 'tx_block', the call will return
* either when the remote receives the data or when 'tx_tout' millisecs
* run out.
* In non-blocking mode, the requests are buffered by the API and a
* non-negative token is returned for each queued request. If the request
* is not queued, a negative token is returned. Upon failure or successful
* TX, the API calls 'tx_done' from atomic context, from which the client
* could submit yet another request.
* The pointer to message should be preserved until it is sent
* over the chan, i.e, tx_done() is made.
* This function could be called from atomic context as it simply
* queues the data and returns a token against the request.
*
* Return: Non-negative integer for successful submission (non-blocking mode)
* or transmission over chan (blocking mode).
* Negative value denotes failure.
*/
int mbox_send_message(struct mbox_chan *chan, void *mssg)
{
int t;
if (!chan || !chan->cl)
return -EINVAL;
t = add_to_rbuf(chan, mssg);
if (t < 0) {
dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
return t;
}
msg_submit(chan);
if (chan->cl->tx_block) {
unsigned long wait;
int ret;
if (!chan->cl->tx_tout) /* wait forever */
wait = msecs_to_jiffies(3600000);
else
wait = msecs_to_jiffies(chan->cl->tx_tout);
ret = wait_for_completion_timeout(&chan->tx_complete, wait);
if (ret == 0) {
t = -ETIME;
tx_tick(chan, t);
}
}
return t;
}
EXPORT_SYMBOL_GPL(mbox_send_message);
/**
* mbox_flush - flush a mailbox channel
* @chan: mailbox channel to flush
* @timeout: time, in milliseconds, to allow the flush operation to succeed
*
* Mailbox controllers that need to work in atomic context can implement the
* ->flush() callback to busy loop until a transmission has been completed.
* The implementation must call mbox_chan_txdone() upon success. Clients can
* call the mbox_flush() function at any time after mbox_send_message() to
* flush the transmission. After the function returns success, the mailbox
* transmission is guaranteed to have completed.
*
* Returns: 0 on success or a negative error code on failure.
*/
int mbox_flush(struct mbox_chan *chan, unsigned long timeout)
{
int ret;
if (!chan->mbox->ops->flush)
return -ENOTSUPP;
ret = chan->mbox->ops->flush(chan, timeout);
if (ret < 0)
tx_tick(chan, ret);
return ret;
}
EXPORT_SYMBOL_GPL(mbox_flush);
/**
* mbox_request_channel - Request a mailbox channel.
* @cl: Identity of the client requesting the channel.
* @index: Index of mailbox specifier in 'mboxes' property.
*
* The Client specifies its requirements and capabilities while asking for
* a mailbox channel. It can't be called from atomic context.
* The channel is exclusively allocated and can't be used by another
* client before the owner calls mbox_free_channel.
* After assignment, any packet received on this channel will be
* handed over to the client via the 'rx_callback'.
* The framework holds reference to the client, so the mbox_client
* structure shouldn't be modified until the mbox_free_channel returns.
*
* Return: Pointer to the channel assigned to the client if successful.
* ERR_PTR for request failure.
*/
struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
{
struct device *dev = cl->dev;
struct mbox_controller *mbox;
struct of_phandle_args spec;
struct mbox_chan *chan;
unsigned long flags;
int ret;
if (!dev || !dev->of_node) {
pr_debug("%s: No owner device node\n", __func__);
return ERR_PTR(-ENODEV);
}
mutex_lock(&con_mutex);
if (of_parse_phandle_with_args(dev->of_node, "mboxes",
"#mbox-cells", index, &spec)) {
dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
mutex_unlock(&con_mutex);
return ERR_PTR(-ENODEV);
}
chan = ERR_PTR(-EPROBE_DEFER);
list_for_each_entry(mbox, &mbox_cons, node)
if (mbox->dev->of_node == spec.np) {
chan = mbox->of_xlate(mbox, &spec);
if (!IS_ERR(chan))
break;
}
of_node_put(spec.np);
if (IS_ERR(chan)) {
mutex_unlock(&con_mutex);
return chan;
}
if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
dev_dbg(dev, "%s: mailbox not free\n", __func__);
mutex_unlock(&con_mutex);
return ERR_PTR(-EBUSY);
}
spin_lock_irqsave(&chan->lock, flags);
chan->msg_free = 0;
chan->msg_count = 0;
chan->active_req = NULL;
chan->cl = cl;
init_completion(&chan->tx_complete);
if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
chan->txdone_method = TXDONE_BY_ACK;
spin_unlock_irqrestore(&chan->lock, flags);
if (chan->mbox->ops->startup) {
ret = chan->mbox->ops->startup(chan);
if (ret) {
dev_err(dev, "Unable to startup the chan (%d)\n", ret);
mbox_free_channel(chan);
chan = ERR_PTR(ret);
}
}
mutex_unlock(&con_mutex);
return chan;
}
EXPORT_SYMBOL_GPL(mbox_request_channel);
struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
const char *name)
{
struct device_node *np = cl->dev->of_node;
struct property *prop;
const char *mbox_name;
int index = 0;
if (!np) {
dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
return ERR_PTR(-EINVAL);
}
if (!of_get_property(np, "mbox-names", NULL)) {
dev_err(cl->dev,
"%s() requires an \"mbox-names\" property\n", __func__);
return ERR_PTR(-EINVAL);
}
of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
if (!strncmp(name, mbox_name, strlen(name)))
return mbox_request_channel(cl, index);
index++;
}
dev_err(cl->dev, "%s() could not locate channel named \"%s\"\n",
__func__, name);
return ERR_PTR(-EINVAL);
}
EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
/**
* mbox_free_channel - The client relinquishes control of a mailbox
* channel by this call.
* @chan: The mailbox channel to be freed.
*/
void mbox_free_channel(struct mbox_chan *chan)
{
unsigned long flags;
if (!chan || !chan->cl)
return;
if (chan->mbox->ops->shutdown)
chan->mbox->ops->shutdown(chan);
/* The queued TX requests are simply aborted, no callbacks are made */
spin_lock_irqsave(&chan->lock, flags);
chan->cl = NULL;
chan->active_req = NULL;
if (chan->txdone_method == TXDONE_BY_ACK)
chan->txdone_method = TXDONE_BY_POLL;
module_put(chan->mbox->dev->driver->owner);
spin_unlock_irqrestore(&chan->lock, flags);
}
EXPORT_SYMBOL_GPL(mbox_free_channel);
static struct mbox_chan *
of_mbox_index_xlate(struct mbox_controller *mbox,
const struct of_phandle_args *sp)
{
int ind = sp->args[0];
if (ind >= mbox->num_chans)
return ERR_PTR(-EINVAL);
return &mbox->chans[ind];
}
/**
* mbox_controller_register - Register the mailbox controller
* @mbox: Pointer to the mailbox controller.
*
* The controller driver registers its communication channels
*/
int mbox_controller_register(struct mbox_controller *mbox)
{
int i, txdone;
/* Sanity check */
if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
return -EINVAL;
if (mbox->txdone_irq)
txdone = TXDONE_BY_IRQ;
else if (mbox->txdone_poll)
txdone = TXDONE_BY_POLL;
else /* It has to be ACK then */
txdone = TXDONE_BY_ACK;
if (txdone == TXDONE_BY_POLL) {
if (!mbox->ops->last_tx_done) {
dev_err(mbox->dev, "last_tx_done method is absent\n");
return -EINVAL;
}
hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
HRTIMER_MODE_REL);
mbox->poll_hrt.function = txdone_hrtimer;
}
for (i = 0; i < mbox->num_chans; i++) {
struct mbox_chan *chan = &mbox->chans[i];
chan->cl = NULL;
chan->mbox = mbox;
chan->txdone_method = txdone;
spin_lock_init(&chan->lock);
}
if (!mbox->of_xlate)
mbox->of_xlate = of_mbox_index_xlate;
mutex_lock(&con_mutex);
list_add_tail(&mbox->node, &mbox_cons);
mutex_unlock(&con_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(mbox_controller_register);
/**
* mbox_controller_unregister - Unregister the mailbox controller
* @mbox: Pointer to the mailbox controller.
*/
void mbox_controller_unregister(struct mbox_controller *mbox)
{
int i;
if (!mbox)
return;
mutex_lock(&con_mutex);
list_del(&mbox->node);
for (i = 0; i < mbox->num_chans; i++)
mbox_free_channel(&mbox->chans[i]);
if (mbox->txdone_poll)
hrtimer_cancel(&mbox->poll_hrt);
mutex_unlock(&con_mutex);
}
EXPORT_SYMBOL_GPL(mbox_controller_unregister);
static void __devm_mbox_controller_unregister(struct device *dev, void *res)
{
struct mbox_controller **mbox = res;
mbox_controller_unregister(*mbox);
}
static int devm_mbox_controller_match(struct device *dev, void *res, void *data)
{
struct mbox_controller **mbox = res;
if (WARN_ON(!mbox || !*mbox))
return 0;
return *mbox == data;
}
/**
* devm_mbox_controller_register() - managed mbox_controller_register()
* @dev: device owning the mailbox controller being registered
* @mbox: mailbox controller being registered
*
* This function adds a device-managed resource that will make sure that the
* mailbox controller, which is registered using mbox_controller_register()
* as part of this function, will be unregistered along with the rest of
* device-managed resources upon driver probe failure or driver removal.
*
* Returns 0 on success or a negative error code on failure.
*/
int devm_mbox_controller_register(struct device *dev,
struct mbox_controller *mbox)
{
struct mbox_controller **ptr;
int err;
ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr),
GFP_KERNEL);
if (!ptr)
return -ENOMEM;
err = mbox_controller_register(mbox);
if (err < 0) {
devres_free(ptr);
return err;
}
devres_add(dev, ptr);
*ptr = mbox;
return 0;
}
EXPORT_SYMBOL_GPL(devm_mbox_controller_register);
/**
* devm_mbox_controller_unregister() - managed mbox_controller_unregister()
* @dev: device owning the mailbox controller being unregistered
* @mbox: mailbox controller being unregistered
*
* This function unregisters the mailbox controller and removes the device-
* managed resource that was set up to automatically unregister the mailbox
* controller on driver probe failure or driver removal. It's typically not
* necessary to call this function.
*/
void devm_mbox_controller_unregister(struct device *dev, struct mbox_controller *mbox)
{
WARN_ON(devres_release(dev, __devm_mbox_controller_unregister,
devm_mbox_controller_match, mbox));
}
EXPORT_SYMBOL_GPL(devm_mbox_controller_unregister);