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