Re: [PATCH v3 2/8] mailbox: arm_mhu: add driver for ARM MHU controller

[Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>]

On Fri, Jan 09, 2015 at 07:28:09PM +0800, Vincent Yang wrote:
> +static irqreturn_t mhu_rx_interrupt(int irq, void *p)
> +{
> +	struct mbox_chan *chan = p;
> +	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;
> +	u32 val;
> +
> +	pr_debug("%s:%d\n", __func__, __LINE__);
> +	val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
> +	mbox_chan_received_data(chan, (void *)val);
> +
> +	writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
> +
> +	return IRQ_HANDLED;

What if 'val' was zero - is the interrupt still "handled" ?

> +static int mhu_startup(struct mbox_chan *chan)
> +{
> +	struct mhu_link *mlink = (struct mhu_link *)chan->con_priv;

Casts from void * are not necessary (repeated many times.)

> +	u32 val;
> +	int ret;
> +
> +	pr_debug("%s:%d\n", __func__, __LINE__);
> +	val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
> +	writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
> +
> +	ret = request_irq(mlink->irq, mhu_rx_interrupt,
> +			  IRQF_SHARED, "mhu_link", chan);
> +	if (unlikely(ret)) {
> +		pr_err("Unable to aquire IRQ\n");
> +		return ret;
> +	}
> +
> +	return 0;

Needlessly complicated, and doesn't need that unlikely().  Also doesn't
print the reason for failure, and merely printing "Unable to aquire IRQ"
into the kernel log with no indication what produced it is silly.  You
have the device struct (via chan->mbox->dev), so using dev_err() is a
definite possibility and improvement.

I'm sure this can be cleaned up and simplified.

> +static int arm_mhu_probe(struct platform_device *pdev)
> +{
> +	int i, err;
> +	struct arm_mhu *mhu;
> +	struct resource *res;
> +	int mhu_reg[3] = {0x0, 0x20, 0x200};
> +
> +	/* Allocate memory for device */
> +	mhu = kzalloc(sizeof(*mhu), GFP_KERNEL);
> +	if (!mhu)
> +		return -ENOMEM;

Consider using dev_kzalloc().

> +
> +	mhu->clk = clk_get(&pdev->dev, "clk");

devm_clk_get().

> +	if (unlikely(IS_ERR(mhu->clk)))
> +		dev_info(&pdev->dev, "unable to init clock\n");
> +	else
> +		clk_prepare_enable(mhu->clk);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mhu->base = ioremap(res->start, resource_size(res));

That's an oops waiting to happen.  Consider using devm_ioremap_resource()
which will check for !res.

> +	if (!mhu->base) {
> +		dev_err(&pdev->dev, "ioremap failed.\n");
> +		kfree(mhu);
> +		return -EBUSY;
> +	}
> +
> +	for (i = 0; i < 3; i++) {
> +		mhu->chan[i].con_priv = &mhu->mlink[i];
> +		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
> +		mhu->mlink[i].irq = res->start;
> +		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
> +		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + 0x100;
> +	}
> +
> +	mhu->mbox.dev = &pdev->dev;
> +	mhu->mbox.chans = &mhu->chan[0];
> +	mhu->mbox.num_chans = 3;
> +	mhu->mbox.ops = &mhu_ops;
> +	mhu->mbox.txdone_irq = false;
> +	mhu->mbox.txdone_poll = true;
> +	mhu->mbox.txpoll_period = 10;
> +
> +	platform_set_drvdata(pdev, mhu);
> +
> +	err = mbox_controller_register(&mhu->mbox);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to register mailboxes %d\n", err);
> +		iounmap(mhu->base);

You don't clk_put() the clock here.  Using devm_* as suggested above
means you wouldn't have made this mistake here...

> +		kfree(mhu);
> +	} else {
> +		dev_info(&pdev->dev, "ARM MHU Mailbox registered\n");
> +	}
> +
> +	return 0;

Always returns success even if mbox_controller_register() fails?

> +}
> +
> +static int arm_mhu_remove(struct platform_device *pdev)
> +{
> +	struct arm_mhu *mhu = platform_get_drvdata(pdev);
> +
> +	mbox_controller_unregister(&mhu->mbox);
> +
> +	iounmap(mhu->base);
> +
> +	if (!IS_ERR(mhu->clk))
> +		clk_disable_unprepare(mhu->clk);

No clk_put() ?  If you used devm_* stuff as suggested above, you wouldn't
need to...

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