char: broadcom: Add vcio module

Add module for accessing the mailbox property channel through
/dev/vcio. Was previously in bcm2708-vcio.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>

drivers/char/broadcom/Kconfig

@@ -22,6 +22,12 @@ config BCM2708_VCMEM
         help
           Helper for videocore memory access and total size allocation.
 
+config BCM_VCIO
+	tristate "Mailbox userspace access"
+	depends on BCM2835_MBOX
+	help
+	  Gives access to the mailbox property channel from userspace.
+
 endif
 
 config BCM_VC_SM

drivers/char/broadcom/Makefile

@@ -1,5 +1,6 @@
 obj-$(CONFIG_BCM_VC_CMA)	+= vc_cma/
 obj-$(CONFIG_BCM2708_VCMEM)	+= vc_mem.o
+obj-$(CONFIG_BCM_VCIO)		+= vcio.o
 obj-$(CONFIG_BCM_VC_SM)         += vc_sm/
 
 obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o

drivers/char/broadcom/vcio.c

@@ -0,0 +1,175 @@
+/*
+ *  Copyright (C) 2010 Broadcom
+ *  Copyright (C) 2015 Noralf Trønnes
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/ioctl.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define MBOX_CHAN_PROPERTY 8
+
+#define VCIO_IOC_MAGIC 100
+#define IOCTL_MBOX_PROPERTY _IOWR(VCIO_IOC_MAGIC, 0, char *)
+
+static struct {
+	dev_t devt;
+	struct cdev cdev;
+	struct class *class;
+	struct rpi_firmware *fw;
+} vcio;
+
+static int vcio_user_property_list(void *user)
+{
+	u32 *buf, size;
+	int ret;
+
+	/* The first 32-bit is the size of the buffer */
+	if (copy_from_user(&size, user, sizeof(size)))
+		return -EFAULT;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, user, size)) {
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	/* Strip off protocol encapsulation */
+	ret = rpi_firmware_property_list(vcio.fw, &buf[2], size - 12);
+	if (ret) {
+		kfree(buf);
+		return ret;
+	}
+
+	buf[1] = RPI_FIRMWARE_STATUS_SUCCESS;
+	if (copy_to_user(user, buf, size))
+		ret = -EFAULT;
+
+	kfree(buf);
+
+	return ret;
+}
+
+static int vcio_device_open(struct inode *inode, struct file *file)
+{
+	try_module_get(THIS_MODULE);
+
+	return 0;
+}
+
+static int vcio_device_release(struct inode *inode, struct file *file)
+{
+	module_put(THIS_MODULE);
+
+	return 0;
+}
+
+static long vcio_device_ioctl(struct file *file, unsigned int ioctl_num,
+			      unsigned long ioctl_param)
+{
+	switch (ioctl_num) {
+	case IOCTL_MBOX_PROPERTY:
+		return vcio_user_property_list((void *)ioctl_param);
+	default:
+		pr_err("unknown ioctl: %d\n", ioctl_num);
+		return -EINVAL;
+	}
+}
+
+const struct file_operations vcio_fops = {
+	.unlocked_ioctl = vcio_device_ioctl,
+	.open = vcio_device_open,
+	.release = vcio_device_release,
+};
+
+static int __init vcio_init(void)
+{
+	struct device_node *np;
+	static struct device *dev;
+	int ret;
+
+	np = of_find_compatible_node(NULL, NULL,
+				     "raspberrypi,bcm2835-firmware");
+/* Uncomment this when we only boot with Device Tree
+	if (!of_device_is_available(np))
+		return -ENODEV;
+*/
+	vcio.fw = rpi_firmware_get(np);
+	if (!vcio.fw)
+		return -ENODEV;
+
+	ret = alloc_chrdev_region(&vcio.devt, 0, 1, "vcio");
+	if (ret) {
+		pr_err("failed to allocate device number\n");
+		return ret;
+	}
+
+	cdev_init(&vcio.cdev, &vcio_fops);
+	vcio.cdev.owner = THIS_MODULE;
+	ret = cdev_add(&vcio.cdev, vcio.devt, 1);
+	if (ret) {
+		pr_err("failed to register device\n");
+		goto err_unregister_chardev;
+	}
+
+	/*
+	 * Create sysfs entries
+	 * 'bcm2708_vcio' is used for backwards compatibility so we don't break
+	 * userspace. Raspian has a udev rule that changes the permissions.
+	 */
+	vcio.class = class_create(THIS_MODULE, "bcm2708_vcio");
+	if (IS_ERR(vcio.class)) {
+		ret = PTR_ERR(vcio.class);
+		pr_err("failed to create class\n");
+		goto err_cdev_del;
+	}
+
+	dev = device_create(vcio.class, NULL, vcio.devt, NULL, "vcio");
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		pr_err("failed to create device\n");
+		goto err_class_destroy;
+	}
+
+	return 0;
+
+err_class_destroy:
+	class_destroy(vcio.class);
+err_cdev_del:
+	cdev_del(&vcio.cdev);
+err_unregister_chardev:
+	unregister_chrdev_region(vcio.devt, 1);
+
+	return ret;
+}
+module_init(vcio_init);
+
+static void __exit vcio_exit(void)
+{
+	device_destroy(vcio.class, vcio.devt);
+	class_destroy(vcio.class);
+	cdev_del(&vcio.cdev);
+	unregister_chrdev_region(vcio.devt, 1);
+}
+module_exit(vcio_exit);
+
+MODULE_AUTHOR("Gray Girling");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_DESCRIPTION("Mailbox userspace access");
+MODULE_LICENSE("GPL");