omap:iommu-char driver interface for tlb entries

This patch provides char driver interface to IOMMU to program
tlb entries directly from user space.

Todo:
plug the reset mechanism as part of iommu_get function.

Signed-off-by: Hari Kanigeri <h-kangieri2@ti.com>

3 files changed, 177 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/omap-iommu.c b/arch/arm/mach-omap2/omap-iommu.c
index f5a1aad1a5c0..8411c105c399 100644
--- a/arch/arm/mach-omap2/omap-iommu.c
+++ b/arch/arm/mach-omap2/omap-iommu.c
@@ -88,6 +88,16 @@ static struct platform_device *omap4_iommu_pdev[NR_OMAP4_IOMMU_DEVICES];
 
 static struct platform_device **omap_iommu_pdev;
 
+int iommu_get_plat_data_size()
+{
+	return num_iommu_devices;
+}
+
+struct iommu_device *iommu_get_device_data(void)
+{
+	return devices;
+}
+
 static int __init omap_iommu_init(void)
 {
 	int i, err;
diff --git a/arch/arm/plat-omap/include/plat/iommu.h b/arch/arm/plat-omap/include/plat/iommu.h
index 33c7d41cb6a5..a45a0b1c348f 100644
--- a/arch/arm/plat-omap/include/plat/iommu.h
+++ b/arch/arm/plat-omap/include/plat/iommu.h
@@ -13,6 +13,9 @@
 #ifndef __MACH_IOMMU_H
 #define __MACH_IOMMU_H
 
+#include <linux/device.h>
+#include <linux/cdev.h>
+
 struct iotlb_entry {
 	u32 da;
 	u32 pa;
@@ -50,6 +53,8 @@ struct iommu {
 	int (*isr)(struct iommu *obj);
 
 	void *ctx; /* iommu context: registres saved area */
+	struct cdev cdev;
+	int minor;
 };
 
 struct cr_regs {
@@ -105,6 +110,11 @@ struct iommu_platform_data {
 	const int nr_tlb_entries;
 };
 
+#define IOMMU_IOC_MAGIC		'I'
+
+#define IOMMU_IOCSETTLBENT	_IO(IOMMU_IOC_MAGIC, 0)
+
+
 #if defined(CONFIG_ARCH_OMAP1)
 #error "iommu for this processor not implemented yet"
 #else
@@ -167,4 +177,5 @@ extern int foreach_iommu_device(void *data,
 extern ssize_t iommu_dump_ctx(struct iommu *obj, char *buf, ssize_t len);
 extern size_t dump_tlb_entries(struct iommu *obj, char *buf, ssize_t len);
 
+extern int iommu_get_plat_data_size(void);
 #endif /* __MACH_IOMMU_H */
diff --git a/arch/arm/plat-omap/iommu.c b/arch/arm/plat-omap/iommu.c
index aa064e1d02e5..5d1bf0eb64e6 100644
--- a/arch/arm/plat-omap/iommu.c
+++ b/arch/arm/plat-omap/iommu.c
@@ -25,10 +25,23 @@
 
 #include "iopgtable.h"
 
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+
+
 #define for_each_iotlb_cr(obj, n, __i, cr)				\
 	for (__i = 0;							\
 	     (__i < (n)) && (cr = __iotlb_read_cr((obj), __i), true);	\
 	     __i++)
+#define OMAP_IOMMU_NAME "omap-iommu"
+
+static atomic_t		num_of_iommus;
+static struct class	*omap_iommu_class;
+static dev_t		omap_iommu_dev;
+
 
 /* accommodate the difference between omap1 and omap2/3 */
 static const struct iommu_functions *arch_iommu;
@@ -176,7 +189,6 @@ static void iotlb_lock_get(struct iommu *obj, struct iotlb_lock *l)
 
 	l->base = MMU_LOCK_BASE(val);
 	l->vict = MMU_LOCK_VICT(val);
-
 }
 
 static void iotlb_lock_set(struct iommu *obj, struct iotlb_lock *l)
@@ -874,6 +886,85 @@ void iommu_put(struct iommu *obj)
 }
 EXPORT_SYMBOL_GPL(iommu_put);
 
+struct omap_iommu_dev {
+	struct device *dev;
+	struct cdev cdev;
+	atomic_t count;
+	int state;
+	int minor;
+};
+
+static int omap_iommu_open(struct inode *inode, struct file *filp)
+{
+	int ret = 0;
+	struct iommu *obj;
+
+	obj = container_of(inode->i_cdev, struct iommu, cdev);
+	if (!obj->dev)
+		return -EINVAL;
+
+	filp->private_data = obj;
+	iommu_get(obj->name);
+
+	return ret;
+}
+
+static int omap_iommu_release(struct inode *inode, struct file *filp)
+{
+	struct iommu *obj;
+	obj = container_of(inode->i_cdev, struct iommu, cdev);
+	if (!obj->dev)
+		return -EINVAL;
+	iommu_put(obj);
+	return 0;
+}
+
+static int omap_iommu_ioctl(struct inode *inode, struct file *filp,
+				unsigned int cmd, unsigned long args)
+
+{
+	struct iommu *obj;
+	int ret = 0;
+
+	obj = filp->private_data;
+	if (!obj)
+		return -EINVAL;
+
+	if (_IOC_TYPE(cmd) != IOMMU_IOC_MAGIC)
+		return -ENOTTY;
+
+	switch (cmd) {
+	case IOMMU_IOCSETTLBENT:
+	{
+		struct iotlb_entry e;
+		int size;
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		size = copy_from_user(&e, (void __user *)args,
+					sizeof(struct iotlb_entry));
+		if (size) {
+			ret = -EINVAL;
+			goto err_user_buf;
+		}
+		load_iotlb_entry(obj, &e);
+		break;
+	}
+	default:
+		return -ENOTTY;
+	}
+err_user_buf:
+	return ret;
+}
+
+
+static const struct file_operations omap_iommu_fops = {
+	.owner		=	THIS_MODULE,
+	.open		=	omap_iommu_open,
+	.release	=	omap_iommu_release,
+	.ioctl		=	omap_iommu_ioctl,
+};
+
+
 /*
  *	OMAP Device MMU(IOMMU) detection
  */
@@ -885,6 +976,9 @@ static int __devinit omap_iommu_probe(struct platform_device *pdev)
 	struct iommu *obj;
 	struct resource *res;
 	struct iommu_platform_data *pdata = pdev->dev.platform_data;
+	int major, minor;
+	struct device *tmpdev;
+	int ret = 0;
 
 	if (pdev->num_resources != 2)
 		return -EINVAL;
@@ -948,8 +1042,42 @@ static int __devinit omap_iommu_probe(struct platform_device *pdev)
 	BUG_ON(!IS_ALIGNED((unsigned long)obj->iopgd, IOPGD_TABLE_SIZE));
 
 	dev_info(&pdev->dev, "%s registered\n", obj->name);
+
+	major = MAJOR(omap_iommu_dev);
+	minor = atomic_read(&num_of_iommus);
+	atomic_inc(&num_of_iommus);
+
+	obj->minor = minor;
+
+	cdev_init(&obj->cdev, &omap_iommu_fops);
+	obj->cdev.owner = THIS_MODULE;
+	ret = cdev_add(&obj->cdev, MKDEV(major, minor), 1);
+	if (ret) {
+		dev_err(&pdev->dev, "%s: cdev_add failed: %d\n", __func__, ret);
+		goto err_cdev;
+	}
+
+	tmpdev = device_create(omap_iommu_class, NULL,
+				MKDEV(major, minor),
+				NULL,
+				OMAP_IOMMU_NAME "%d", minor);
+	if (IS_ERR(tmpdev)) {
+		ret = PTR_ERR(tmpdev);
+		pr_err("%s: device_create failed: %d\n", __func__, ret);
+		goto clean_cdev;
+	}
+
+	pr_info("%s initialized %s, major: %d, base-minor: %d\n",
+			OMAP_IOMMU_NAME,
+			pdata->name,
+			MAJOR(omap_iommu_dev),
+			minor);
+
 	return 0;
 
+clean_cdev:
+	cdev_del(&obj->cdev);
+err_cdev:
 err_pgd:
 	free_irq(irq, obj);
 err_irq:
@@ -967,6 +1095,10 @@ static int __devexit omap_iommu_remove(struct platform_device *pdev)
 	int irq;
 	struct resource *res;
 	struct iommu *obj = platform_get_drvdata(pdev);
+	int major = MAJOR(omap_iommu_dev);
+
+	device_destroy(omap_iommu_class, MKDEV(major, obj->minor));
+	cdev_del(&obj->cdev);
 
 	platform_set_drvdata(pdev, NULL);
 
@@ -998,11 +1130,13 @@ static void iopte_cachep_ctor(void *iopte)
 	clean_dcache_area(iopte, IOPTE_TABLE_SIZE);
 }
 
+
 static int __init omap_iommu_init(void)
 {
 	struct kmem_cache *p;
 	const unsigned long flags = SLAB_HWCACHE_ALIGN;
 	size_t align = 1 << 10; /* L2 pagetable alignement */
+	int ret, num;
 
 	p = kmem_cache_create("iopte_cache", IOPTE_TABLE_SIZE, align, flags,
 			      iopte_cachep_ctor);
@@ -1010,7 +1144,28 @@ static int __init omap_iommu_init(void)
 		return -ENOMEM;
 	iopte_cachep = p;
 
+	num = iommu_get_plat_data_size();
+	ret = alloc_chrdev_region(&omap_iommu_dev, 0, num, OMAP_IOMMU_NAME);
+
+	if (ret) {
+		pr_err("%s: alloc_chrdev_region failed: %d\n", __func__, ret);
+		goto out;
+	}
+
+	omap_iommu_class = class_create(THIS_MODULE, OMAP_IOMMU_NAME);
+	if (IS_ERR(omap_iommu_class)) {
+		ret = PTR_ERR(omap_iommu_class);
+		pr_err("%s: class_create failed: %d\n", __func__, ret);
+		goto unreg_region;
+	}
+	atomic_set(&num_of_iommus, 0);
+
 	return platform_driver_register(&omap_iommu_driver);
+
+unreg_region:
+	unregister_chrdev_region(omap_iommu_dev, num);
+out:
+	return ret;
 }
 module_init(omap_iommu_init);