Re: [PATCH v2 4/5] drivers/mailbox: Add aspeed ast2400/ast2500 mbox driver

[Andrew Jeffery <andrew@aj.id.au>]

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Hi Cyril,

This looks good to me. A couple of minor comments below.

On Thu, 2016-12-22 at 17:06 +1100, Cyril Bur wrote:
> This provides access to the mbox registers on the ast2400 and ast2500 boards.
> 
> An ioctl() is used to allow users to write to a specific register with a specific
> value. This is useful as the other end have configured the mbox registers to
> provide an interrupt when a specific regster gets written to.
> 
> > Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
> ---
>  drivers/mailbox/Kconfig          |   9 +
>  drivers/mailbox/Makefile         |   3 +
>  drivers/mailbox/aspeed-mbox.c    | 354 +++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/aspeed-mbox.h |  23 +++
>  4 files changed, 389 insertions(+)
>  create mode 100644 drivers/mailbox/aspeed-mbox.c
>  create mode 100644 include/uapi/linux/aspeed-mbox.h
> 
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 5305923752d2..815cfe852dea 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -123,4 +123,13 @@ config XGENE_SLIMPRO_MBOX
> >  	  It is used to send short messages between ARM64-bit cores and
> >  	  the SLIMpro Management Engine, primarily for PM. Say Y here if you
> >  	  want to use the APM X-Gene SLIMpro IPCM support.
> +
> +config ASPEED_MBOX
> > +	depends on ARCH_ASPEED || COMPILE_TEST
> > +	bool "Aspeed ast2400/2500 Mailbox Controller"
> > +	default "y"
> > +	---help---
> > +	  Provides a driver for the MBOX regsiters found on Aspeed SOCs
> > +	  (AST2400 and AST2500). This driver provides a device for aspeed
> > +	  mbox registers
>  endif
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index 0be3e742bb7d..99d17f3b9552 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -25,3 +25,6 @@ obj-$(CONFIG_TI_MESSAGE_MANAGER) += ti-msgmgr.o
>  obj-$(CONFIG_XGENE_SLIMPRO_MBOX) += mailbox-xgene-slimpro.o
>  
> >  obj-$(CONFIG_HI6220_MBOX)	+= hi6220-mailbox.o
> +
> > +obj-$(CONFIG_ASPEED_MBOX)		+= aspeed-mbox.o
> +
> diff --git a/drivers/mailbox/aspeed-mbox.c b/drivers/mailbox/aspeed-mbox.c
> new file mode 100644
> index 000000000000..a5da7fc0fd23
> --- /dev/null
> +++ b/drivers/mailbox/aspeed-mbox.c
> @@ -0,0 +1,354 @@
> +/*
> + * Copyright 2016 IBM Corporation
> + *
> + * 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; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/errno.h>
> +#include <linux/poll.h>
> +#include <linux/sched.h>
> +#include <linux/spinlock.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/miscdevice.h>
> +#include <linux/timer.h>
> +#include <linux/jiffies.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/aspeed-mbox.h>
> +
> > +#define DEVICE_NAME	"aspeed-mbox"
> +
> +#define MBOX_NUM_REGS 16
> +#define MBOX_NUM_DATA_REGS 14
> +
> +#define MBOX_DATA_0 0x00
> +#define MBOX_STATUS_0 0x40
> +#define MBOX_STATUS_1 0x44
> +#define MBOX_BMC_CTRL 0x48
> +#define   MBOX_CTRL_RECV BIT(7)
> +#define   MBOX_CTRL_MASK BIT(1)
> +#define   MBOX_CTRL_SEND BIT(0)
> +#define MBOX_HOST_CTRL 0x4c
> +#define MBOX_INTERRUPT_0 0x50
> +#define MBOX_INTERRUPT_1 0x54
> +
> +struct mbox {
> > > +	struct miscdevice	miscdev;
> > > +	struct regmap		*regmap;
> > > +	unsigned int		base;
> > > +	int			irq;
> > > +	wait_queue_head_t	queue;
> > > +	struct timer_list	poll_timer;
> +};
> +
> +static atomic_t mbox_open_count = ATOMIC_INIT(0);
> +
> +static u8 mbox_inb(struct mbox *mbox, int reg)
> +{
> > +	/*
> > +	 * The mbox registers are actually only 1 byte but are addressed 4
> > +	 * bytes appart. The other three bytes are marked 'reserved', they
> > +	 * *should* be zero but lets not rely on it.
> > +	 * I am going to rely on the fact we can casually read/write to them...
> > +	 */
> > +	unsigned int val = 0xff; /* If regmap throws an error return 0xff */
> > +	regmap_read(mbox->regmap, mbox->base + reg, &val);
> +	return val & 0xff;
> +}
> +
> +static void mbox_outb(struct mbox *mbox, u8 data, int reg)
> +{
> +	regmap_write(mbox->regmap, mbox->base + reg, data);

We could use regmap_update_bits() here, but ultimately it's not going
to matter. Should we say something if regmap_write() fails (it
shouldn't, but if it does that's extra concerning)?

> +}
> +
> +static struct mbox *file_mbox(struct file *file)
> +{
> > +	return container_of(file->private_data, struct mbox, miscdev);
> +}
> +
> +static int mbox_open(struct inode *inode, struct file *file)
> +{
> > +	struct mbox *mbox = file_mbox(file);
> +
> > +	if (atomic_inc_return(&mbox_open_count) == 1) {
> > +		/*
> > +		 * Clear the interrupt status bit if it was left on and unmask
> > +		 * interrupts.
> > +		 * MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step
> > +		 */
> > +		mbox_outb(mbox, MBOX_CTRL_RECV, MBOX_BMC_CTRL);
> > +		return 0;
> > +	}
> +
> > +	atomic_dec(&mbox_open_count);
> > +	return -EBUSY;
> +}
> +
> +static ssize_t mbox_read(struct file *file, char __user *buf,
> > +				size_t count, loff_t *ppos)
> +{
> > +	struct mbox *mbox = file_mbox(file);
> > +	char __user *p = buf;
> > +	int i;
> +
> > +	if (!access_ok(VERIFY_WRITE, buf, count))
> > +		return -EFAULT;
> +
> > +	WARN_ON(*ppos);
> +
> > +	if (wait_event_interruptible(mbox->queue,
> > +		mbox_inb(mbox, MBOX_BMC_CTRL) & MBOX_CTRL_RECV))
> > +		return -ERESTARTSYS;
> +
> > +	for (i = 0; i < MBOX_NUM_DATA_REGS; i++)
> > +		if (__put_user(mbox_inb(mbox, MBOX_DATA_0 + (i * 4)), p++))
> > +			return -EFAULT;
> +
> > +	/* MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step */
> > +	mbox_outb(mbox, MBOX_CTRL_RECV, MBOX_BMC_CTRL);
> > +	return p - buf;
> +}
> +
> +static ssize_t mbox_write(struct file *file, const char __user *buf,
> > +				size_t count, loff_t *ppos)
> +{
> > +	struct mbox *mbox = file_mbox(file);
> > +	const char __user *p = buf;
> > +	char c;
> > +	int i;
> +
> > +	if (!access_ok(VERIFY_READ, buf, count))
> > +		return -EFAULT;
> +
> > +	WARN_ON(*ppos);
> +
> > +	for (i = 0; i < MBOX_NUM_DATA_REGS; i++) {
> > +		if (__get_user(c, p))
> > +			return -EFAULT;
> +
> > +		mbox_outb(mbox, c, MBOX_DATA_0 + (i * 4));
> > +		p++;
> > +	}
> +
> > +	mbox_outb(mbox, MBOX_CTRL_SEND, MBOX_BMC_CTRL);
> +
> > +	return p - buf;
> +}
> +
> +static long mbox_ioctl(struct file *file, unsigned int cmd,
> > +		unsigned long param)
> +{
> > +	struct aspeed_mbox_atn atn;
> > +	struct mbox *mbox = file_mbox(file);
> > +	void __user *p = (void __user *)param;
> +
> > +	switch (cmd) {
> +	case ASPEED_MBOX_IOCTL_ATN:

I think we should rename the IOCTL as what we do below doesn't
necessarily raise an interrupt.

> +		if (copy_from_user(&atn, p, sizeof(atn)))
> > +			return -EFAULT;
> > +		if (atn.reg > 15)
> > +			return -EINVAL;
> +
> > +		mbox_outb(mbox, atn.val, atn.reg);
> > +		return 0;
> > +	}
> +
> > +	return -EINVAL;
> +}
> +
> +static unsigned int mbox_poll(struct file *file, poll_table *wait)
> +{
> > +	struct mbox *mbox = file_mbox(file);
> > +	unsigned int mask = 0;
> +
> > +	poll_wait(file, &mbox->queue, wait);
> +
> > +	if (mbox_inb(mbox, MBOX_BMC_CTRL) & MBOX_CTRL_RECV)
> > +		mask |= POLLIN;
> +
> > +	return mask;
> +}
> +
> +static int mbox_release(struct inode *inode, struct file *file)
> +{
> > +	atomic_dec(&mbox_open_count);
> > +	return 0;
> +}
> +
> +static const struct file_operations mbox_fops = {
> > > +	.owner		= THIS_MODULE,
> > > +	.open		= mbox_open,
> > > +	.read		= mbox_read,
> > > +	.write		= mbox_write,
> > > +	.release	= mbox_release,
> > > +	.poll		= mbox_poll,
> > > +	.unlocked_ioctl	= mbox_ioctl,
> +};
> +
> +static void poll_timer(unsigned long data)
> +{
> > +	struct mbox *mbox = (void *)data;
> +
> > +	mbox->poll_timer.expires += msecs_to_jiffies(500);
> > +	wake_up(&mbox->queue);
> > +	add_timer(&mbox->poll_timer);
> +}
> +
> +static irqreturn_t mbox_irq(int irq, void *arg)
> +{
> > +	struct mbox *mbox = arg;
> +
> > +	if (!(mbox_inb(mbox, MBOX_BMC_CTRL) & MBOX_CTRL_RECV))
> > +		return IRQ_NONE;
> +
> > +	/*
> > +	 * Leave the status bit set so that we know the data is for us,
> > +	 * clear it once it has been read.
> > +	 */
> +
> > +	/* Mask it off, we'll clear it when we the data gets read */
> > +	mbox_outb(mbox, MBOX_CTRL_MASK, MBOX_BMC_CTRL);
> +
> > +	wake_up(&mbox->queue);
> > +	return IRQ_HANDLED;
> +}
> +
> +static int mbox_config_irq(struct mbox *mbox,
> > +		struct platform_device *pdev)
> +{
> > +	struct device *dev = &pdev->dev;
> > +	int rc;
> +
> > +	mbox->irq = irq_of_parse_and_map(dev->of_node, 0);
> > +	if (!mbox->irq)
> > +		return -ENODEV;
> +
> > +	rc = devm_request_irq(dev, mbox->irq, mbox_irq, IRQF_SHARED,
> > +			DEVICE_NAME, mbox);
> > +	if (rc < 0) {
> > +		dev_warn(dev, "Unable to request IRQ %d\n", mbox->irq);
> > +		mbox->irq = 0;
> > +		return rc;
> > +	}
> +
> > +	/*
> > +	 * Disable all register based interrupts, we'll have to change
> > +	 * this, protocol seemingly will require regs 0 and 15
> > +	 */
> > +	mbox_outb(mbox, 0x00, MBOX_INTERRUPT_0); /* regs 0 - 7 */
> > +	mbox_outb(mbox, 0x00, MBOX_INTERRUPT_1); /* regs 8 - 15 */
> +
> > +	/* W1C */
> > +	mbox_outb(mbox, 0xff, MBOX_STATUS_0);
> > +	mbox_outb(mbox, 0xff, MBOX_STATUS_1);
> +
> > +	mbox_outb(mbox, MBOX_CTRL_RECV, MBOX_BMC_CTRL);
> > +	return 0;
> +}
> +
> +static int mbox_probe(struct platform_device *pdev)
> +{
> > +	struct mbox *mbox;
> > +	struct device *dev;
> > +	int rc;
> +
> > +	if (!pdev || !pdev->dev.of_node)
> > +		return -ENODEV;
> +
> > +	dev = &pdev->dev;
> > +	dev_info(dev, "Found mbox host device\n");
> +
> > +	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
> > +	if (!mbox)
> > +		return -ENOMEM;
> +
> > +	dev_set_drvdata(&pdev->dev, mbox);
> +
> > +	rc = of_property_read_u32(dev->of_node, "reg", &mbox->base);
> > +	if (rc) {
> > +		dev_err(dev, "Couldn't read reg device-tree property\n");
> > +		goto out;
> > +	}
> +
> > +	mbox->regmap = syscon_node_to_regmap(
> > +			pdev->dev.parent->of_node);
> > +	if (IS_ERR(mbox->regmap)) {
> > +		dev_err(dev, "Couldn't get regmap\n");
> > +		rc = -ENODEV;
> > +		goto out;
> > +	}
> +
> > +	init_waitqueue_head(&mbox->queue);
> +
> > +	mbox->miscdev.minor = MISC_DYNAMIC_MINOR;
> > +	mbox->miscdev.name = DEVICE_NAME;
> > +	mbox->miscdev.fops = &mbox_fops;
> > +	mbox->miscdev.parent = dev;
> > +	rc = misc_register(&mbox->miscdev);
> > +	if (rc) {
> > +		dev_err(dev, "Unable to register device\n");
> > +		goto out;
> > +	}
> +
> > +	mbox_config_irq(mbox, pdev);
> +
> > +	if (mbox->irq) {
> > +		dev_info(dev, "Using IRQ %d\n", mbox->irq);
> > +	} else {
> > +		dev_info(dev, "No IRQ; using timer\n");
> > +		setup_timer(&mbox->poll_timer, poll_timer,
> > +				(unsigned long)mbox);
> > +		mbox->poll_timer.expires = jiffies + msecs_to_jiffies(10);
> > +		add_timer(&mbox->poll_timer);
> > +	}
> +
> +out:
> > +	return rc;
> +
> +}
> +
> +static int mbox_remove(struct platform_device *pdev)
> +{
> > +	struct mbox *mbox = dev_get_drvdata(&pdev->dev);
> +
> > +	misc_deregister(&mbox->miscdev);
> > +	if (!mbox->irq)
> > +		del_timer_sync(&mbox->poll_timer);
> > +	mbox = NULL;
> +
> > +	return 0;
> +}
> +
> +static const struct of_device_id mbox_match[] = {
> > +	{ .compatible = "aspeed,ast2400-mbox" },
> > +	{ },
> +};
> +
> +static struct platform_driver mbox_driver = {
> > +	.driver = {
> > > +		.name		= DEVICE_NAME,
> > +		.of_match_table = mbox_match,
> > +	},
> > +	.probe = mbox_probe,
> > +	.remove = mbox_remove,
> +};
> +
> +module_platform_driver(mbox_driver);
> +
> +MODULE_DEVICE_TABLE(of, mbox_match);
> +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Cyril Bur <cyrilbur@gmail.com>");
> +MODULE_DESCRIPTION("Linux device interface to the Aspeed MBOX registers");
> diff --git a/include/uapi/linux/aspeed-mbox.h b/include/uapi/linux/aspeed-mbox.h
> new file mode 100644
> index 000000000000..f4e6a9242fd0
> --- /dev/null
> +++ b/include/uapi/linux/aspeed-mbox.h
> @@ -0,0 +1,23 @@
> +/*
> + * Copyright 2016 IBM Corp.
> + *
> + * 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; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#ifndef _UAPI_LINUX_MBOX_HOST_H
> +#define _UAPI_LINUX_MBOX_HOST_H
> +
> +#include <linux/ioctl.h>
> +
> +struct aspeed_mbox_atn {
> > +	uint8_t reg;
> > +	uint8_t val;
> +};
> +
> > +#define __ASPEED_MBOX_IOCTL_MAGIC	0xb1
> > +#define ASPEED_MBOX_IOCTL_ATN	_IOW(__ASPEED_MBOX_IOCTL_MAGIC, 0x00, struct aspeed_mbox_atn)
> +
> +#endif /* _UAPI_LINUX_MBOX_HOST_H */

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