drivers/mailbox/aspeed-mbox.c - linux - Git at Google

 /*
  * 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/interrupt.h>
 #include <linux/mfd/syscon.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/poll.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>

 #define DEVICE_NAME	"aspeed-mbox"

 #define ASPEED_MBOX_NUM_REGS 16

 #define ASPEED_MBOX_DATA_0 0x00
 #define ASPEED_MBOX_STATUS_0 0x40
 #define ASPEED_MBOX_STATUS_1 0x44
 #define ASPEED_MBOX_BMC_CTRL 0x48
 #define   ASPEED_MBOX_CTRL_RECV BIT(7)
 #define   ASPEED_MBOX_CTRL_MASK BIT(1)
 #define   ASPEED_MBOX_CTRL_SEND BIT(0)
 #define ASPEED_MBOX_HOST_CTRL 0x4c
 #define ASPEED_MBOX_INTERRUPT_0 0x50
 #define ASPEED_MBOX_INTERRUPT_1 0x54

 struct aspeed_mbox {
 	struct miscdevice	miscdev;
 	struct regmap		*regmap;
 	unsigned int		base;
 	wait_queue_head_t	queue;
 	struct mutex		mutex;
 };

 static atomic_t aspeed_mbox_open_count = ATOMIC_INIT(0);

 static u8 aspeed_mbox_inb(struct aspeed_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 aspeed_mbox_outb(struct aspeed_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 aspeed_mbox *file_mbox(struct file *file)
 {
 	return container_of(file->private_data, struct aspeed_mbox, miscdev);
 }

 static int aspeed_mbox_open(struct inode *inode, struct file *file)
 {
 	struct aspeed_mbox *mbox = file_mbox(file);

 	if (atomic_inc_return(&aspeed_mbox_open_count) == 1) {
 		/*
 		 * Clear the interrupt status bit if it was left on and unmask
 		 * interrupts.
 		 * ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step
 		 */
 		aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
 		return 0;
 	}

 	atomic_dec(&aspeed_mbox_open_count);
 	return -EBUSY;
 }

 static ssize_t aspeed_mbox_read(struct file *file, char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	struct aspeed_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 > ASPEED_MBOX_NUM_REGS)
 		return -EINVAL;

 	if (file->f_flags & O_NONBLOCK) {
 		if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
 				ASPEED_MBOX_CTRL_RECV))
 			return -EAGAIN;
 	} else if (wait_event_interruptible(mbox->queue,
 				aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
 				ASPEED_MBOX_CTRL_RECV)) {
 		return -ERESTARTSYS;
 	}

 	mutex_lock(&mbox->mutex);

 	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
 		uint8_t reg = aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4));

 		ret = __put_user(reg, p);
 		if (ret)
 			goto out_unlock;

 		p++;
 		count--;
 	}

 	/* ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step */
 	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
 	ret = p - buf;

 out_unlock:
 	mutex_unlock(&mbox->mutex);
 	return ret;
 }

 static ssize_t aspeed_mbox_write(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	struct aspeed_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 > ASPEED_MBOX_NUM_REGS)
 		return -EINVAL;

 	mutex_lock(&mbox->mutex);

 	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
 		ret = __get_user(c, p);
 		if (ret)
 			goto out_unlock;

 		aspeed_mbox_outb(mbox, c, ASPEED_MBOX_DATA_0 + (i * 4));
 		p++;
 		count--;
 	}

 	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_SEND, ASPEED_MBOX_BMC_CTRL);
 	ret = p - buf;

 out_unlock:
 	mutex_unlock(&mbox->mutex);
 	return ret;
 }

 static unsigned int aspeed_mbox_poll(struct file *file, poll_table *wait)
 {
 	struct aspeed_mbox *mbox = file_mbox(file);
 	unsigned int mask = 0;

 	poll_wait(file, &mbox->queue, wait);

 	if (aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_MBOX_CTRL_RECV)
 		mask |= POLLIN;

 	return mask;
 }

 static int aspeed_mbox_release(struct inode *inode, struct file *file)
 {
 	atomic_dec(&aspeed_mbox_open_count);
 	return 0;
 }

 static const struct file_operations aspeed_mbox_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= no_seek_end_llseek,
 	.read		= aspeed_mbox_read,
 	.write		= aspeed_mbox_write,
 	.open		= aspeed_mbox_open,
 	.release	= aspeed_mbox_release,
 	.poll		= aspeed_mbox_poll,
 };

 static irqreturn_t aspeed_mbox_irq(int irq, void *arg)
 {
 	struct aspeed_mbox *mbox = arg;

 	if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_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 */
 	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_MASK, ASPEED_MBOX_BMC_CTRL);

 	wake_up(&mbox->queue);
 	return IRQ_HANDLED;
 }

 static int aspeed_mbox_config_irq(struct aspeed_mbox *mbox,
 		struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	int rc, irq;

 	irq = irq_of_parse_and_map(dev->of_node, 0);
 	if (!irq)
 		return -ENODEV;

 	rc = devm_request_irq(dev, irq, aspeed_mbox_irq,
 			IRQF_SHARED, DEVICE_NAME, mbox);
 	if (rc < 0) {
 		dev_err(dev, "Unable to request IRQ %d\n", irq);
 		return rc;
 	}

 	/*
 	 * Disable all register based interrupts.
 	 */
 	aspeed_mbox_outb(mbox, 0x00, ASPEED_MBOX_INTERRUPT_0); /* regs 0 - 7 */
 	aspeed_mbox_outb(mbox, 0x00, ASPEED_MBOX_INTERRUPT_1); /* regs 8 - 15 */

 	/* These registers are write one to clear. Clear them. */
 	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_0);
 	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_1);

 	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
 	return 0;
 }

 static int aspeed_mbox_probe(struct platform_device *pdev)
 {
 	struct aspeed_mbox *mbox;
 	struct device *dev;
 	int rc;

 	dev = &pdev->dev;

 	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");
 		return rc;
 	}

 	mbox->regmap = syscon_node_to_regmap(
 			pdev->dev.parent->of_node);
 	if (IS_ERR(mbox->regmap)) {
 		dev_err(dev, "Couldn't get regmap\n");
 		return -ENODEV;
 	}

 	mutex_init(&mbox->mutex);
 	init_waitqueue_head(&mbox->queue);

 	mbox->miscdev.minor = MISC_DYNAMIC_MINOR;
 	mbox->miscdev.name = DEVICE_NAME;
 	mbox->miscdev.fops = &aspeed_mbox_fops;
 	mbox->miscdev.parent = dev;
 	rc = misc_register(&mbox->miscdev);
 	if (rc) {
 		dev_err(dev, "Unable to register device\n");
 		return rc;
 	}

 	rc = aspeed_mbox_config_irq(mbox, pdev);
 	if (rc) {
 		dev_err(dev, "Failed to configure IRQ\n");
 		misc_deregister(&mbox->miscdev);
 		return rc;
 	}

 	return 0;
 }

 static int aspeed_mbox_remove(struct platform_device *pdev)
 {
 	struct aspeed_mbox *mbox = dev_get_drvdata(&pdev->dev);

 	misc_deregister(&mbox->miscdev);

 	return 0;
 }

 static const struct of_device_id aspeed_mbox_match[] = {
 	{ .compatible = "aspeed,ast2400-mbox" },
 	{ .compatible = "aspeed,ast2500-mbox" },
 	{ },
 };

 static struct platform_driver aspeed_mbox_driver = {
 	.driver = {
 		.name		= DEVICE_NAME,
 		.of_match_table = aspeed_mbox_match,
 	},
 	.probe = aspeed_mbox_probe,
 	.remove = aspeed_mbox_remove,
 };

 module_platform_driver(aspeed_mbox_driver);

 MODULE_DEVICE_TABLE(of, aspeed_mbox_match);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Cyril Bur <cyrilbur@gmail.com>");
 MODULE_DESCRIPTION("ASpeed mailbox device driver");
	/*
	* 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/interrupt.h>
	#include <linux/mfd/syscon.h>
	#include <linux/miscdevice.h>
	#include <linux/module.h>
	#include <linux/of_irq.h>
	#include <linux/platform_device.h>
	#include <linux/poll.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>

	#define DEVICE_NAME "aspeed-mbox"

	#define ASPEED_MBOX_NUM_REGS 16

	#define ASPEED_MBOX_DATA_0 0x00
	#define ASPEED_MBOX_STATUS_0 0x40
	#define ASPEED_MBOX_STATUS_1 0x44
	#define ASPEED_MBOX_BMC_CTRL 0x48
	#define ASPEED_MBOX_CTRL_RECV BIT(7)
	#define ASPEED_MBOX_CTRL_MASK BIT(1)
	#define ASPEED_MBOX_CTRL_SEND BIT(0)
	#define ASPEED_MBOX_HOST_CTRL 0x4c
	#define ASPEED_MBOX_INTERRUPT_0 0x50
	#define ASPEED_MBOX_INTERRUPT_1 0x54

	struct aspeed_mbox {
	struct miscdevice miscdev;
	struct regmap *regmap;
	unsigned int base;
	wait_queue_head_t queue;
	struct mutex mutex;
	};

	static atomic_t aspeed_mbox_open_count = ATOMIC_INIT(0);

	static u8 aspeed_mbox_inb(struct aspeed_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 aspeed_mbox_outb(struct aspeed_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 aspeed_mbox file_mbox(struct file file)
	{
	return container_of(file->private_data, struct aspeed_mbox, miscdev);
	}

	static int aspeed_mbox_open(struct inode inode, struct file file)
	{
	struct aspeed_mbox *mbox = file_mbox(file);

	if (atomic_inc_return(&aspeed_mbox_open_count) == 1) {
	/*
	* Clear the interrupt status bit if it was left on and unmask
	* interrupts.
	* ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step
	*/
	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
	return 0;
	}

	atomic_dec(&aspeed_mbox_open_count);
	return -EBUSY;
	}

	static ssize_t aspeed_mbox_read(struct file file, char __user buf,
	size_t count, loff_t *ppos)
	{
	struct aspeed_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 > ASPEED_MBOX_NUM_REGS)
	return -EINVAL;

	if (file->f_flags & O_NONBLOCK) {
	if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
	ASPEED_MBOX_CTRL_RECV))
	return -EAGAIN;
	} else if (wait_event_interruptible(mbox->queue,
	aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
	ASPEED_MBOX_CTRL_RECV)) {
	return -ERESTARTSYS;
	}

	mutex_lock(&mbox->mutex);

	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
	uint8_t reg = aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4));

	ret = __put_user(reg, p);
	if (ret)
	goto out_unlock;

	p++;
	count--;
	}

	/* ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step */
	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
	ret = p - buf;

	out_unlock:
	mutex_unlock(&mbox->mutex);
	return ret;
	}

	static ssize_t aspeed_mbox_write(struct file file, const char __user buf,
	size_t count, loff_t *ppos)
	{
	struct aspeed_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 > ASPEED_MBOX_NUM_REGS)
	return -EINVAL;

	mutex_lock(&mbox->mutex);

	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
	ret = __get_user(c, p);
	if (ret)
	goto out_unlock;

	aspeed_mbox_outb(mbox, c, ASPEED_MBOX_DATA_0 + (i * 4));
	p++;
	count--;
	}

	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_SEND, ASPEED_MBOX_BMC_CTRL);
	ret = p - buf;

	out_unlock:
	mutex_unlock(&mbox->mutex);
	return ret;
	}

	static unsigned int aspeed_mbox_poll(struct file file, poll_table wait)
	{
	struct aspeed_mbox *mbox = file_mbox(file);
	unsigned int mask = 0;

	poll_wait(file, &mbox->queue, wait);

	if (aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_MBOX_CTRL_RECV)
	mask \|= POLLIN;

	return mask;
	}

	static int aspeed_mbox_release(struct inode inode, struct file file)
	{
	atomic_dec(&aspeed_mbox_open_count);
	return 0;
	}

	static const struct file_operations aspeed_mbox_fops = {
	.owner = THIS_MODULE,
	.llseek = no_seek_end_llseek,
	.read = aspeed_mbox_read,
	.write = aspeed_mbox_write,
	.open = aspeed_mbox_open,
	.release = aspeed_mbox_release,
	.poll = aspeed_mbox_poll,
	};

	static irqreturn_t aspeed_mbox_irq(int irq, void *arg)
	{
	struct aspeed_mbox *mbox = arg;

	if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_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 */
	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_MASK, ASPEED_MBOX_BMC_CTRL);

	wake_up(&mbox->queue);
	return IRQ_HANDLED;
	}

	static int aspeed_mbox_config_irq(struct aspeed_mbox *mbox,
	struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	int rc, irq;

	irq = irq_of_parse_and_map(dev->of_node, 0);
	if (!irq)
	return -ENODEV;

	rc = devm_request_irq(dev, irq, aspeed_mbox_irq,
	IRQF_SHARED, DEVICE_NAME, mbox);
	if (rc < 0) {
	dev_err(dev, "Unable to request IRQ %d\n", irq);
	return rc;
	}

	/*
	* Disable all register based interrupts.
	*/
	aspeed_mbox_outb(mbox, 0x00, ASPEED_MBOX_INTERRUPT_0); /* regs 0 - 7 */
	aspeed_mbox_outb(mbox, 0x00, ASPEED_MBOX_INTERRUPT_1); /* regs 8 - 15 */

	/* These registers are write one to clear. Clear them. */
	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_0);
	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_1);

	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
	return 0;
	}

	static int aspeed_mbox_probe(struct platform_device *pdev)
	{
	struct aspeed_mbox *mbox;
	struct device *dev;
	int rc;

	dev = &pdev->dev;

	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");
	return rc;
	}

	mbox->regmap = syscon_node_to_regmap(
	pdev->dev.parent->of_node);
	if (IS_ERR(mbox->regmap)) {
	dev_err(dev, "Couldn't get regmap\n");
	return -ENODEV;
	}

	mutex_init(&mbox->mutex);
	init_waitqueue_head(&mbox->queue);

	mbox->miscdev.minor = MISC_DYNAMIC_MINOR;
	mbox->miscdev.name = DEVICE_NAME;
	mbox->miscdev.fops = &aspeed_mbox_fops;
	mbox->miscdev.parent = dev;
	rc = misc_register(&mbox->miscdev);
	if (rc) {
	dev_err(dev, "Unable to register device\n");
	return rc;
	}

	rc = aspeed_mbox_config_irq(mbox, pdev);
	if (rc) {
	dev_err(dev, "Failed to configure IRQ\n");
	misc_deregister(&mbox->miscdev);
	return rc;
	}

	return 0;
	}

	static int aspeed_mbox_remove(struct platform_device *pdev)
	{
	struct aspeed_mbox *mbox = dev_get_drvdata(&pdev->dev);

	misc_deregister(&mbox->miscdev);

	return 0;
	}

	static const struct of_device_id aspeed_mbox_match[] = {
	{ .compatible = "aspeed,ast2400-mbox" },
	{ .compatible = "aspeed,ast2500-mbox" },
	{ },
	};

	static struct platform_driver aspeed_mbox_driver = {
	.driver = {
	.name = DEVICE_NAME,
	.of_match_table = aspeed_mbox_match,
	},
	.probe = aspeed_mbox_probe,
	.remove = aspeed_mbox_remove,
	};

	module_platform_driver(aspeed_mbox_driver);

	MODULE_DEVICE_TABLE(of, aspeed_mbox_match);
	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Cyril Bur <cyrilbur@gmail.com>");
	MODULE_DESCRIPTION("ASpeed mailbox device driver");