Re: [PATCHv4 2/2] mailbox: Adding driver for Xilinx LogiCORE IP mailbox.

Josh Cartwright
2015-06-16T18:45:18Z

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Hey Moritz-

A few comments below:

On Mon, Jun 01, 2015 at 09:18:27AM -0700, Moritz Fischer wrote:
[..]
> +++ b/drivers/mailbox/mailbox-xilinx.c
> @@ -0,0 +1,352 @@
> +/*
> + * Copyright (c) 2015, National Instruments Corp. All rights reserved.
> + *
> + * Driver for the Xilinx LogiCORE mailbox IP block
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.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/platform_device.h>
> +
> +#define DRIVER_NAME "xilinx-mailbox"

Does KBUILD_MODNAME already give you what you need?

> +
> +/* register offsets */
> +#define MAILBOX_REG_WRDATA 0x00
> +#define MAILBOX_REG_RDDATA 0x08
> +#define MAILBOX_REG_STATUS 0x10
> +#define MAILBOX_REG_ERROR 0x14
> +#define MAILBOX_REG_SIT 0x18
> +#define MAILBOX_REG_RIT 0x1c
> +#define MAILBOX_REG_IS 0x20
> +#define MAILBOX_REG_IE 0x24
> +#define MAILBOX_REG_IP 0x28
> +
> +/* status register */
> +#define STS_RTA BIT(3)
> +#define STS_STA BIT(2)
> +#define STS_FULL BIT(1)
> +#define STS_EMPTY BIT(0)
> +
> +/* error register */
> +#define ERR_FULL BIT(1)
> +#define ERR_EMPTY BIT(0)
> +
> +/* mailbox interrupt status register */
> +#define INT_STATUS_ERR BIT(2)
> +#define INT_STATUS_RTI BIT(1)
> +#define INT_STATUS_STI BIT(0)
> +
> +/* mailbox interrupt enable register */
> +#define INT_ENABLE_ERR BIT(2)
> +#define INT_ENABLE_RTI BIT(1)
> +#define INT_ENABLE_STI BIT(0)
> +
> +#define MBOX_POLLING_MS 5 /* polling interval 5ms */
> +
> +struct xilinx_mbox {
> + int irq;
> + void __iomem *mbox_base;
> + struct clk *clk;
> + struct device *dev;
> + struct mbox_controller controller;
> +
> + /* if the controller supports only RX polling mode */
> + struct timer_list rxpoll_timer;
> +};
> +
> +static struct xilinx_mbox *mbox_chan_to_xilinx_mbox(struct mbox_chan *chan)
> +{
> + if (!chan || !chan->con_priv)

The chan->con_priv check is unnecessary.

> + return NULL;
> +
> + return (struct xilinx_mbox *)chan->con_priv;

Nit: Unnecessary cast.

[..]
> +static int xilinx_mbox_startup(struct mbox_chan *chan)
> +{
> + int ret;
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + if (mbox->irq > 0) {
> + ret = request_irq(mbox->irq, xilinx_mbox_interrupt, 0,
> + dev_name(mbox->dev), chan);
> + if (unlikely(ret)) {
> + dev_err(mbox->dev,
> + "failed to register mailbox interrupt:%d\n",
> + ret);
> + return ret;
> + }
> +
> + xilinx_mbox_rx_intmask(mbox, true);
> +
> + /* if fifo was full already, we didn't get an interrupt */
> + while (xilinx_mbox_pending(mbox))
> + xilinx_mbox_rx_data(chan);
> +
> + return 0;
> + }
> +
> + /* setup polling timer */
> + setup_timer(&mbox->rxpoll_timer, xilinx_mbox_poll_rx,
> + (unsigned long)chan);
> + mod_timer(&mbox->rxpoll_timer,
> + jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
> +
> + return 0;
> +}
> +
> +static int xilinx_mbox_send_data(struct mbox_chan *chan, void *data)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> + u32 *udata = (u32 *)data;

Nit: Unnecessary cast.

> +
> + if (!mbox || !data)
> + return -EINVAL;
> +
> + if (xilinx_mbox_full(mbox))
> + return -EBUSY;
> +
> + /* enable interrupt before send */
> + if (mbox->irq >= 0)

You seem to be inconsistent in checking mbox->irq >=0 (here) vs. >0 (in
probe).

> + xilinx_mbox_tx_intmask(mbox, true);
> +
> + writel_relaxed(*udata, mbox->mbox_base + MAILBOX_REG_WRDATA);
> +
> + return 0;
> +}
> +
> +static bool xilinx_mbox_last_tx_done(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + /* return false if mailbox is full */
> + return !xilinx_mbox_full(mbox);
> +}
> +
> +static bool xilinx_mbox_peek_data(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + return xilinx_mbox_pending(mbox);

> +
> +static void xilinx_mbox_shutdown(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + if (mbox->irq > 0) {
> + /* mask all interrupts */
> + writel_relaxed(0, mbox->mbox_base + MAILBOX_REG_IE);
> + free_irq(mbox->irq, chan);
> + } else {
> + del_timer_sync(&mbox->rxpoll_timer);
> + }
> +}
> +
> +static struct mbox_chan_ops xilinx_mbox_ops = {

const?

I'm also wondering if it's a bit cleaner to define two mbox_ops, one for
polling and one for when the device is interrupt driven.

> + .send_data = xilinx_mbox_send_data,
> + .startup = xilinx_mbox_startup,
> + .shutdown = xilinx_mbox_shutdown,
> + .last_tx_done = xilinx_mbox_last_tx_done,
> + .peek_data = xilinx_mbox_peek_data,
> +};
> +
> +static int xilinx_mbox_probe(struct platform_device *pdev)
> +{
> + struct xilinx_mbox *mbox;
> + struct resource *regs;
> + struct mbox_chan *chans;
> + int ret;
> +
> + mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
> + if (!mbox)
> + return -ENOMEM;
> +
> + /* get clk and enable */
> + mbox->clk = devm_clk_get(&pdev->dev, "mbox");
> + if (IS_ERR(mbox->clk)) {
> + dev_err(&pdev->dev, "Couldn't get clk.\n");
> + return PTR_ERR(mbox->clk);
> + }
> +
> + /* allocated one channel */
> + chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
> + if (!chans)
> + return -ENOMEM;

You know statically the number of channels (one), so why not just
include the struct mbox_chan in struct xilinx_mbox (admittedly, I'm not
too familiar with the mailbox subsystem's lifetime guarantees).

> +
> + regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> + mbox->mbox_base = devm_ioremap_resource(&pdev->dev, regs);
> + if (IS_ERR(mbox->mbox_base))
> + return PTR_ERR(mbox->mbox_base);
> +
> + mbox->irq = platform_get_irq(pdev, 0);
> + /* if irq is present, we can use it, otherwise, poll */
> + if (mbox->irq > 0) {
> + mbox->controller.txdone_irq = true;
> + } else {
> + dev_info(&pdev->dev, "IRQ not found, fallback to polling.\n");
> + mbox->controller.txdone_poll = true;
> + mbox->controller.txpoll_period = MBOX_POLLING_MS;
> + }
> +
> + mbox->dev = &pdev->dev;
> +
> + /* hardware supports only one channel. */
> + chans[0].con_priv = mbox;
> + mbox->controller.dev = mbox->dev;
> + mbox->controller.num_chans = 1;
> + mbox->controller.chans = chans;
> + mbox->controller.ops = &xilinx_mbox_ops;
> +
> + /* prep and enable the clock */
> + clk_prepare_enable(mbox->clk);

I know you've already moved where clock management has been done once,
but I'm wondering if clock management be done in startup/shutdown
instead of in probe()?

> + ret = mbox_controller_register(&mbox->controller);
> + if (ret) {
> + dev_err(&pdev->dev, "Register mailbox failed\n");
> + clk_disable_unprepare(mbox->clk);
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, mbox);
> +
> + return 0;
> +}
> +
> +static int xilinx_mbox_remove(struct platform_device *pdev)
> +{
> + struct xilinx_mbox *mbox = platform_get_drvdata(pdev);
> +
> + if (!mbox)

How could this happen?

> + return -EINVAL;
> +
> + mbox_controller_unregister(&mbox->controller);
> +
> + clk_disable_unprepare(mbox->clk);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id xilinx_mbox_match[] = {
> + { .compatible = "xlnx,mailbox-2.1" },
> + { /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, xilinx_mbox_match);
> +
> +static struct platform_driver xilinx_mbox_driver = {
> + .probe = xilinx_mbox_probe,
> + .remove = xilinx_mbox_remove,
> + .driver = {
> + .name = DRIVER_NAME,
> + .of_match_table = xilinx_mbox_match,
> + },
> +};
> +
> +module_platform_driver(xilinx_mbox_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Xilinx mailbox specific functions");
> +MODULE_AUTHOR("Moritz Fischer <moritz.fischer@ettus.com>");
> +MODULE_ALIAS("platform:xilinx-mailbox");
> --
> 2.4.1
>
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