On Tue, Jun 21, 2016 at 3:32 PM, Neil Armstrong [off-list ref] wrote:

Add Amlogic Meson SoCs Message-Handling-Unit as mailbox controller
with 2 independent channels/links to communicate with a remote processor.

Signed-off-by: Neil Armstrong <redacted>
---
 drivers/mailbox/Makefile    |   2 +
 drivers/mailbox/meson_mhu.c | 199 ++++++++++++++++++++++++++++++++++++++++++++

Can we call it pdev_mhu.c or similar so that some other platform using
the MHU as a platform_device wouldn't have to embarrassingly call it
'Meson's MHU'?  And also the replace meson with that prefix in the
code.

How about sync with arm_mhu.c by doing writel_relaxed(val,
mlink->rx_reg + INTR_CLR_OFS) ?

+       return IRQ_HANDLED;
+}
+
+static bool meson_mhu_last_tx_done(struct mbox_chan *chan)
+{
+       struct meson_mhu_link *mlink = chan->con_priv;
+       u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+
+       return (val == 0);
+}
+
+static int meson_mhu_send_data(struct mbox_chan *chan, void *data)
+{
+       struct meson_mhu_link *mlink = chan->con_priv;
+       u32 *arg = data;
+
+       writel_relaxed(*arg, mlink->tx_reg + INTR_SET_OFS);
+
+       return 0;
+}
+
+static int meson_mhu_startup(struct mbox_chan *chan)
+{
+       struct meson_mhu_link *mlink = chan->con_priv;
+       int ret;
+

arm_mhu.c clears any pending TX before taking over by doing ...
       val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
       writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);

+       ret = request_irq(mlink->irq, meson_mhu_rx_interrupt,
+                         IRQF_ONESHOT, "meson_mhu_link", chan);
+       if (ret) {
+               dev_err(chan->mbox->dev,
+                       "Unable to acquire IRQ %d\n", mlink->irq);
+               return ret;
+       }
+
+       return 0;
+}
+
+static void meson_mhu_shutdown(struct mbox_chan *chan)
+{
+       struct meson_mhu_link *mlink = chan->con_priv;
+
+       free_irq(mlink->irq, chan);
+}
+
+static const struct mbox_chan_ops meson_mhu_ops = {
+       .send_data = meson_mhu_send_data,
+       .startup = meson_mhu_startup,
+       .shutdown = meson_mhu_shutdown,
+       .last_tx_done = meson_mhu_last_tx_done,
+};

My two comments above may not be necessary for your platform, but I
would suggest we keep the core (from the declaration of struct
meson_mhu_link to this point) in sync with arm_mhu.c

+static int meson_mhu_probe(struct platform_device *pdev)
+{
+       int i, err;
+       struct meson_mhu *mhu;
+       struct device *dev = &pdev->dev;
+       struct resource *res;
+       int meson_mhu_reg[MHU_CHANS] = {MHU_LP_OFFSET, MHU_HP_OFFSET};
+
+       /* Allocate memory for device */
+       mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
+       if (!mhu)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       mhu->base = devm_ioremap_resource(dev, res);
+       if (IS_ERR(mhu->base)) {
+               dev_err(dev, "ioremap failed\n");
+               return PTR_ERR(mhu->base);
+       }
+
+       for (i = 0; i < MHU_CHANS; i++) {
+               mhu->chan[i].con_priv = &mhu->mlink[i];
+               mhu->mlink[i].irq = platform_get_irq(pdev, i);
+               if (mhu->mlink[i].irq < 0) {
+                       dev_err(dev, "failed to get irq%d\n", i);
+                       return mhu->mlink[i].irq;
+               }
+               mhu->mlink[i].rx_reg = mhu->base + meson_mhu_reg[i];
+               mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
+       }
+
+       mhu->mbox.dev = dev;
+       mhu->mbox.chans = &mhu->chan[0];
+       mhu->mbox.num_chans = MHU_CHANS;
+       mhu->mbox.ops = &meson_mhu_ops;
+       mhu->mbox.txdone_irq = false;
+       mhu->mbox.txdone_poll = true;
+       mhu->mbox.txpoll_period = 1;
+
+       platform_set_drvdata(pdev, mhu);
+
+       err = mbox_controller_register(&mhu->mbox);
+       if (err) {
+               dev_err(dev, "Failed to register mailboxes %d\n", err);
+               return err;
+       }
+
+       dev_info(dev, "Meson MHU Mailbox registered\n");
+       return 0;
+}
+
+static int meson_mhu_remove(struct platform_device *pdev)
+{
+       struct meson_mhu *mhu = platform_get_drvdata(pdev);
+
+       mbox_controller_unregister(&mhu->mbox);
+
+       return 0;
+}
+
+static const struct of_device_id meson_mhu_dt_ids[] = {
+       { .compatible = "amlogic,meson-gxbb-mhu", },
+       { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, meson_mhu_ids);
+
+static struct platform_driver meson_wdt_driver = {
+       .probe  = meson_mhu_probe,
+       .remove = meson_mhu_remove,
+       .driver = {
+               .name = "meson-mhu",
+               .of_match_table = meson_mhu_dt_ids,
+       },
+};
+
+module_platform_driver(meson_wdt_driver);
+

wdt as in watchdog-timer from drivers/watchdog/meson_wdt.c ? :)

Thanks.