// SPDX-License-Identifier: GPL-2.0
//
// Copyright (c) 2017-2019 Samuel Holland <[email protected]>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/spinlock.h>
#define NUM_CHANS 8
#define CTRL_REG(n) (0x0000 + 0x4 * ((n) / 4))
#define CTRL_RX(n) BIT(0 + 8 * ((n) % 4))
#define CTRL_TX(n) BIT(4 + 8 * ((n) % 4))
#define REMOTE_IRQ_EN_REG 0x0040
#define REMOTE_IRQ_STAT_REG 0x0050
#define LOCAL_IRQ_EN_REG 0x0060
#define LOCAL_IRQ_STAT_REG 0x0070
#define RX_IRQ(n) BIT(0 + 2 * (n))
#define RX_IRQ_MASK 0x5555
#define TX_IRQ(n) BIT(1 + 2 * (n))
#define TX_IRQ_MASK 0xaaaa
#define FIFO_STAT_REG(n) (0x0100 + 0x4 * (n))
#define FIFO_STAT_MASK GENMASK(0, 0)
#define MSG_STAT_REG(n) (0x0140 + 0x4 * (n))
#define MSG_STAT_MASK GENMASK(2, 0)
#define MSG_DATA_REG(n) (0x0180 + 0x4 * (n))
#define mbox_dbg(mbox, ...) dev_dbg((mbox)->controller.dev, __VA_ARGS__)
struct sun6i_msgbox {
struct mbox_controller controller;
struct clk *clk;
spinlock_t lock;
void __iomem *regs;
};
static bool sun6i_msgbox_last_tx_done(struct mbox_chan *chan);
static bool sun6i_msgbox_peek_data(struct mbox_chan *chan);
static inline int channel_number(struct mbox_chan *chan)
{
return chan - chan->mbox->chans;
}
static inline struct sun6i_msgbox *to_sun6i_msgbox(struct mbox_chan *chan)
{
return chan->con_priv;
}
static irqreturn_t sun6i_msgbox_irq(int irq, void *dev_id)
{
struct sun6i_msgbox *mbox = dev_id;
uint32_t status;
int n;
/* Only examine channels that are currently enabled. */
status = readl(mbox->regs + LOCAL_IRQ_EN_REG) &
readl(mbox->regs + LOCAL_IRQ_STAT_REG);
if (!(status & RX_IRQ_MASK))
return IRQ_NONE;
for (n = 0; n < NUM_CHANS; ++n) {
struct mbox_chan *chan = &mbox->controller.chans[n];
if (!(status & RX_IRQ(n)))
continue;
while (sun6i_msgbox_peek_data(chan)) {
uint32_t msg = readl(mbox->regs + MSG_DATA_REG(n));
mbox_dbg(mbox, "Channel %d received 0x%08x\n", n, msg);
mbox_chan_received_data(chan, &msg);
}
/* The IRQ can be cleared only once the FIFO is empty. */
writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG);
}
return IRQ_HANDLED;
}
static int sun6i_msgbox_send_data(struct mbox_chan *chan, void *data)
{
struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
int n = channel_number(chan);
uint32_t msg = *(uint32_t *)data;
/* Using a channel backwards gets the hardware into a bad state. */
if (WARN_ON_ONCE(!(readl(mbox->regs + CTRL_REG(n)) & CTRL_TX(n))))
return 0;
writel(msg, mbox->regs + MSG_DATA_REG(n));
mbox_dbg(mbox, "Channel %d sent 0x%08x\n", n, msg);
return 0;
}
static int sun6i_msgbox_startup(struct mbox_chan *chan)
{
struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
int n = channel_number(chan);
/* The coprocessor is responsible for setting channel directions. */
if (readl(mbox->regs + CTRL_REG(n)) & CTRL_RX(n)) {
/* Flush the receive FIFO. */
while (sun6i_msgbox_peek_data(chan))
readl(mbox->regs + MSG_DATA_REG(n));
writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG);
/* Enable the receive IRQ. */
spin_lock(&mbox->lock);
writel(readl(mbox->regs + LOCAL_IRQ_EN_REG) | RX_IRQ(n),
mbox->regs + LOCAL_IRQ_EN_REG);
spin_unlock(&mbox->lock);
}
mbox_dbg(mbox, "Channel %d startup complete\n", n);
return 0;
}
static void sun6i_msgbox_shutdown(struct mbox_chan *chan)
{
struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
int n = channel_number(chan);
if (readl(mbox->regs + CTRL_REG(n)) & CTRL_RX(n)) {
/* Disable the receive IRQ. */
spin_lock(&mbox->lock);
writel(readl(mbox->regs + LOCAL_IRQ_EN_REG) & ~RX_IRQ(n),
mbox->regs + LOCAL_IRQ_EN_REG);
spin_unlock(&mbox->lock);
/* Attempt to flush the FIFO until the IRQ is cleared. */
do {
while (sun6i_msgbox_peek_data(chan))
readl(mbox->regs + MSG_DATA_REG(n));
writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG);
} while (readl(mbox->regs + LOCAL_IRQ_STAT_REG) & RX_IRQ(n));
}
mbox_dbg(mbox, "Channel %d shutdown complete\n", n);
}
static bool sun6i_msgbox_last_tx_done(struct mbox_chan *chan)
{
struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
int n = channel_number(chan);
/*
* The hardware allows snooping on the remote user's IRQ statuses.
* We consider a message to be acknowledged only once the receive IRQ
* for that channel is cleared. Since the receive IRQ for a channel
* cannot be cleared until the FIFO for that channel is empty, this
* ensures that the message has actually been read. It also gives the
* recipient an opportunity to perform minimal processing before
* acknowledging the message.
*/
return !(readl(mbox->regs + REMOTE_IRQ_STAT_REG) & RX_IRQ(n));
}
static bool sun6i_msgbox_peek_data(struct mbox_chan *chan)
{
struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
int n = channel_number(chan);
return readl(mbox->regs + MSG_STAT_REG(n)) & MSG_STAT_MASK;
}
static const struct mbox_chan_ops sun6i_msgbox_chan_ops = {
.send_data = sun6i_msgbox_send_data,
.startup = sun6i_msgbox_startup,
.shutdown = sun6i_msgbox_shutdown,
.last_tx_done = sun6i_msgbox_last_tx_done,
.peek_data = sun6i_msgbox_peek_data,
};
static int sun6i_msgbox_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct mbox_chan *chans;
struct reset_control *reset;
struct sun6i_msgbox *mbox;
int i, ret;
mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
if (!mbox)
return -ENOMEM;
chans = devm_kcalloc(dev, NUM_CHANS, sizeof(*chans), GFP_KERNEL);
if (!chans)
return -ENOMEM;
for (i = 0; i < NUM_CHANS; ++i)
chans[i].con_priv = mbox;
mbox->clk = devm_clk_get(dev, NULL);
if (IS_ERR(mbox->clk)) {
ret = PTR_ERR(mbox->clk);
dev_err(dev, "Failed to get clock: %d\n", ret);
return ret;
}
ret = clk_prepare_enable(mbox->clk);
if (ret) {
dev_err(dev, "Failed to enable clock: %d\n", ret);
return ret;
}
reset = devm_reset_control_get_exclusive(dev, NULL);
if (IS_ERR(reset)) {
ret = PTR_ERR(reset);
dev_err(dev, "Failed to get reset control: %d\n", ret);
goto err_disable_unprepare;
}
/*
* NOTE: We rely on platform firmware to preconfigure the channel
* directions, and we share this hardware block with other firmware
* that runs concurrently with Linux (e.g. a trusted monitor).
*
* Therefore, we do *not* assert the reset line if probing fails or
* when removing the device.
*/
ret = reset_control_deassert(reset);
if (ret) {
dev_err(dev, "Failed to deassert reset: %d\n", ret);
goto err_disable_unprepare;
}
mbox->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(mbox->regs)) {
ret = PTR_ERR(mbox->regs);
dev_err(dev, "Failed to map MMIO resource: %d\n", ret);
goto err_disable_unprepare;
}
/* Disable all IRQs for this end of the msgbox. */
writel(0, mbox->regs + LOCAL_IRQ_EN_REG);
ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0),
sun6i_msgbox_irq, 0, dev_name(dev), mbox);
if (ret) {
dev_err(dev, "Failed to register IRQ handler: %d\n", ret);
goto err_disable_unprepare;
}
mbox->controller.dev = dev;
mbox->controller.ops = &sun6i_msgbox_chan_ops;
mbox->controller.chans = chans;
mbox->controller.num_chans = NUM_CHANS;
mbox->controller.txdone_irq = false;
mbox->controller.txdone_poll = true;
mbox->controller.txpoll_period = 5;
spin_lock_init(&mbox->lock);
platform_set_drvdata(pdev, mbox);
ret = mbox_controller_register(&mbox->controller);
if (ret) {
dev_err(dev, "Failed to register controller: %d\n", ret);
goto err_disable_unprepare;
}
return 0;
err_disable_unprepare:
clk_disable_unprepare(mbox->clk);
return ret;
}
static void sun6i_msgbox_remove(struct platform_device *pdev)
{
struct sun6i_msgbox *mbox = platform_get_drvdata(pdev);
mbox_controller_unregister(&mbox->controller);
/* See the comment in sun6i_msgbox_probe about the reset line. */
clk_disable_unprepare(mbox->clk);
}
static const struct of_device_id sun6i_msgbox_of_match[] = {
{ .compatible = "allwinner,sun6i-a31-msgbox", },
{},
};
MODULE_DEVICE_TABLE(of, sun6i_msgbox_of_match);
static struct platform_driver sun6i_msgbox_driver = {
.driver = {
.name = "sun6i-msgbox",
.of_match_table = sun6i_msgbox_of_match,
},
.probe = sun6i_msgbox_probe,
.remove_new = sun6i_msgbox_remove,
};
module_platform_driver(sun6i_msgbox_driver);
MODULE_AUTHOR("Samuel Holland <[email protected]>");
MODULE_DESCRIPTION("Allwinner sun6i/sun8i/sun9i/sun50i Message Box");
MODULE_LICENSE("GPL v2");
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