[PATCH v3 5/5] drivers/mailbox: Add aspeed ast2400/ast2500 mbox driver
Joel Stanley
joel at jms.id.au
Wed Jan 11 11:33:44 AEDT 2017
On Tue, Jan 10, 2017 at 8:06 PM, Cyril Bur <cyrilbur at gmail.com> wrote:
Nit: make the subject "Add Aspeed mailbox driver".
> This provides access to the mbox registers on the ast2400 and ast2500
> boards.
>
> This driver allows arbitrary reads and writes to the 16 data registers as
> the other end may have configured the mbox hardware to provide an
> interrupt when a specific register gets written to.
>
> Signed-off-by: Cyril Bur <cyrilbur at gmail.com>
> ---
> drivers/mailbox/Kconfig | 9 ++
> drivers/mailbox/Makefile | 3 +
> drivers/mailbox/aspeed-mbox.c | 365 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 377 insertions(+)
> create mode 100644 drivers/mailbox/aspeed-mbox.c
>
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 5305923752d2..b9aebe139b9c 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) && REGMAP && MFD_SYSCON
> + bool "Aspeed ast2400/2500 Mailbox Controller"
> + default "y"
> + ---help---
> + Provides a driver for the MBOX registers 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..6820f73085db
> --- /dev/null
> +++ b/drivers/mailbox/aspeed-mbox.c
> @@ -0,0 +1,365 @@
> +/*
> + * 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/delay.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/jiffies.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/poll.h>
> +#include <linux/regmap.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/timer.h>
> +
> +#define DEVICE_NAME "aspeed-mbox"
> +
> +#define MBOX_NUM_REGS 16
> +
> +#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 {
This is the aspeed mailbox device driver. Kernel convention is to
prefix the functions and structure with aspeed_.
I mentioned this in the first review I did.
> + struct miscdevice miscdev;
> + struct regmap *regmap;
> + unsigned int base;
> + int irq;
> + wait_queue_head_t queue;
> + struct timer_list poll_timer;
> + struct mutex mutex;
> +};
> +
> +static atomic_t mbox_open_count = ATOMIC_INIT(0);
> +
> +static u8 mbox_inb(struct mbox *mbox, int reg)
> +{
> + /*
> + * The mbox registers are actually only one byte but are addressed
> + * four bytes apart. 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 */
> + int rc = regmap_read(mbox->regmap, mbox->base + reg, &val);
> +
> + if (rc)
> + dev_err(mbox->miscdev.parent, "regmap_read() failed with "
> + "%d (reg: 0x%08x)\n", rc, reg);
> +
> + return val & 0xff;
> +}
> +
> +static void mbox_outb(struct mbox *mbox, u8 data, int reg)
> +{
> + int rc = regmap_write(mbox->regmap, mbox->base + reg, data);
> +
> + if (rc)
> + dev_err(mbox->miscdev.parent, "regmap_write() failed with "
> + "%d (data: %u reg: 0x%08x)\n", rc, data, reg);
> +}
> +
> +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;
> + ssize_t ret;
> + int i;
> +
> + if (!access_ok(VERIFY_WRITE, buf, count))
> + return -EFAULT;
> +
> + if (count + *ppos > MBOX_NUM_REGS)
> + return -EINVAL;
> +
> + if ((file->f_flags & O_NONBLOCK) &&
> + !(mbox_inb(mbox, MBOX_BMC_CTRL) & MBOX_CTRL_RECV))
> + return -EAGAIN;
> + else if (wait_event_interruptible(mbox->queue,
> + mbox_inb(mbox, MBOX_BMC_CTRL) & MBOX_CTRL_RECV))
You read MBOX_BMC_CTRL twice. Is that intentional?
I suggest rearranging your code to read the register once.
> + return -ERESTARTSYS;
> +
> + mutex_lock(&mbox->mutex);
> +
> + for (i = *ppos; count > 0 && i < MBOX_NUM_REGS; i++, p++, count--) {
Can this have another couple of variables?
Perhaps increment the pointer in the loop.
> + if (__put_user(mbox_inb(mbox, MBOX_DATA_0 + (i * 4)), p)) {
This is hard to read. Split up the code so you do fewer things on a line.
mbox_inb()
ret = put_user()
if (ret)
goto out;
> + ret = -EFAULT;
> + goto out_unlock;
> + }
> + }
> +
> + /* MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step */
> + mbox_outb(mbox, MBOX_CTRL_RECV, MBOX_BMC_CTRL);
> + ret = p - buf;
> +
> +out_unlock:
> + mutex_unlock(&mbox->mutex);
> + return ret;
> +}
> +
> +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;
> + ssize_t ret;
> + char c;
> + int i;
> +
> + if (!access_ok(VERIFY_READ, buf, count))
> + return -EFAULT;
> +
> + if (count + *ppos > MBOX_NUM_REGS)
> + return -EINVAL;
> +
> + mutex_lock(&mbox->mutex);
> +
> + for (i = *ppos; count > 0 && i < MBOX_NUM_REGS; i++) {
> + if (__get_user(c, p)) {
> + ret = -EFAULT;
> + goto out_unlock;
> + }
> +
> + mbox_outb(mbox, c, MBOX_DATA_0 + (i * 4));
> + p++;
> + count--;
> + }
> +
> + mbox_outb(mbox, MBOX_CTRL_SEND, MBOX_BMC_CTRL);
> + ret = p - buf;
> +
> +out_unlock:
> + mutex_unlock(&mbox->mutex);
> + return ret;
> +}
> +
> +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,
> + .llseek = no_seek_end_llseek,
> + .read = mbox_read,
> + .write = mbox_write,
> + .open = mbox_open,
> + .release = mbox_release,
> + .poll = mbox_poll,
> +};
> +
> +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.
> + */
> + mbox_outb(mbox, 0x00, MBOX_INTERRUPT_0); /* regs 0 - 7 */
> + mbox_outb(mbox, 0x00, MBOX_INTERRUPT_1); /* regs 8 - 15 */
> +
> + /* W1C */
What does this mean?
> + 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;
You return values from the function but don't use them.
> +}
> +
> +static int mbox_probe(struct platform_device *pdev)
> +{
> + struct mbox *mbox;
> + struct device *dev;
> + int rc;
> +
> + if (!pdev || !pdev->dev.of_node)
> + return -ENODEV;
Drop these checks.
> +
> + dev = &pdev->dev;
> + dev_info(dev, "Found mbox host device\n");
Drop this.
> +
> + 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;
You don't do anything in out, so just return here.
> + }
>
> + 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;
Return here.
> + }
> +
> + mutex_init(&mbox->mutex);
> + 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;
Do you need to cleanup the waitqueue?
> + }
> +
> + 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");
What decides if we're using an irq or not? Can we simplify it and only
support one case?
> + 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;
What?
> +
> + return 0;
> +}
> +
> +static const struct of_device_id mbox_match[] = {
> + { .compatible = "aspeed,ast2400-mbox" },
This needs an ast2500 string.
> + { },
> +};
> +
> +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 at gmail.com>");
> +MODULE_DESCRIPTION("Linux device interface to the Aspeed MBOX registers");
Aspeed mailbox device driver?
> --
> 2.11.0
>
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