+mmap

dio.c

@@ -37,38 +37,44 @@ static enum io_type {
 
 static void *inbuf, * outbuf;
 static void *mm;
-int buf_size = 8 * PAGE_SIZE;
+static int buf_size = 16 * 1024;
 static int mmapoffset;
-static int mmapsize;
+static int mmapsize = 16 * 1024;
 static char *dev_name;
 static int ignore_eof;
 
 int output(int dev, void *buf, int len)
 {
+	int ret = 0;
 	if ( dev < 0 )
 		return 0;
 	switch (io_type) {
 	case mmap_io:
+		memcpy(mm,buf,len);
+		ret = len;
 		break;
 	case file_io:
 	default:
-		len = write(dev, buf, len);
+		ret = write(dev, buf, len);
 	}
-	return len;
+	return ret;
 }
 
 int input(int dev, void *buf, int len)
 {
+	int ret;
 	if ( dev < 0 )
 		return 0;
 	switch (io_type) {
 	case mmap_io:
+		memcpy(buf,mm,len);
+		ret = len;
 		break;
 	case file_io:
 	default:
-		len = read(dev, buf, len);
+		ret = read(dev, buf, len);
 	}
-	return len;
+	return ret;
 }
 
 int pipe_start(int dev)
@@ -265,9 +271,10 @@ int main(int argc, char *argv[])
 	chkne(dev = open(dev_name, O_CREAT | O_RDWR,0666));
 	trvd(dev);
 	if (io_type == mmap_io) {
-		mm = mmap(0, mmapsize, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, dev, mmapoffset);
+		mm = mmap(NULL, mmapsize, PROT_READ | PROT_WRITE, MAP_SHARED, dev, mmapoffset);
 		if (mm == MAP_FAILED) {
 			fprintf(stderr, "mmap() failed\n");
+			trvs(strerror(errno));
 			goto exit;
 		}
 	}

ldt-test

@@ -42,7 +42,7 @@ tracing_stop()
 }
 
 # sudo rmmod parport_pc parport  ppdev lp
-sudo rmmod ldt ldt_plat_dev
+sudo rmmod ldt ldt_plat_dev 2> /dev/null
 set -o errexit
 make -s
 sudo insmod ldt.ko irq=$irq

ldt.c

@@ -34,6 +34,10 @@
 #include <linux/miscdevice.h>
 #include <linux/platform_device.h>
 
+static int bufsize = PFN_ALIGN(16 * 1024);
+static void * in_buf;
+static void * out_buf;
+
 int irq = 0;
 module_param(irq, int, 0);
 
@@ -157,6 +161,7 @@ static ssize_t ldt_read(struct file *file, char __user * buf, size_t count, loff
 {
 	int ret;
 	unsigned int copied;
+_entry:
 	// TODO: implement blocking I/O
 	if (mutex_lock_interruptible(&read_lock))
 		return -EINTR;
@@ -171,6 +176,7 @@ static ssize_t ldt_write(struct file *file, const char __user * buf, size_t coun
 {
 	int ret;
 	unsigned int copied;
+_entry:
 
 	if (mutex_lock_interruptible(&write_lock))
 		return -EINTR;
@@ -179,12 +185,53 @@ static ssize_t ldt_write(struct file *file, const char __user * buf, size_t coun
 	return ret ? ret : copied;
 }
 
+void pages_set_reserved(struct page * page, int pages)
+{
+	for (; pages; pages--, page++)
+		SetPageReserved(page);
+}
+
+
+/*	pages_flag - set or clear a flag for sequence of pages
+ *   
+ *	more generic soultion instead SetPageReserved, ClearPageReserved etc
+ */
+
+void pages_flag(struct page * page, int pages, int mask, int value)
+{
+	for (; pages; pages--, page++)
+		if (value)
+			__set_bit(mask, &page->flags);
+		else
+			__clear_bit(mask, &page->flags); 
+
+}
+
+static int ldt_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+       void * buf;
+_entry:
+       if (vma->vm_flags & VM_WRITE)
+	       buf = in_buf;
+       else if (vma->vm_flags & VM_READ)
+	       buf = out_buf;
+
+       //vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);     // PAGE_SHARED
+       if (remap_pfn_range(vma, vma->vm_start, virt_to_phys(in_buf) >> PAGE_SHIFT,
+			       vma->vm_end - vma->vm_start, vma->vm_page_prot)) {
+	       trlm("remap_pfn_range failed");
+	       return -EAGAIN;
+       }
+       return 0;
+}
+
 struct file_operations ldt_fops = {
 	.owner = THIS_MODULE,
 	.open = ldt_open,
 	.release = ldt_release,
 	.read = ldt_read,
 	.write = ldt_write,
+	.mmap = ldt_mmap,
 	.poll = NULL,
 };
 
@@ -205,7 +252,19 @@ static __devinit int ldt_probe(struct platform_device *pdev)
 	trvs_(KBUILD_MODNAME);
 	trvp_(pdev);
 	trvd_(irq);
+	trvd_(bufsize);
 	trln();
+	if (!( in_buf = alloc_pages_exact(bufsize, GFP_KERNEL | __GFP_ZERO) )) { 
+		ret = - ENOMEM;
+		goto exit;
+	}
+	pages_flag(virt_to_page(in_buf), PFN_UP(bufsize), PG_reserved,1);
+	if (!( out_buf = alloc_pages_exact(bufsize, GFP_KERNEL | __GFP_ZERO) )) { 
+		ret = - ENOMEM;
+		goto exit;
+	}
+	pages_flag(virt_to_page(out_buf), PFN_UP(bufsize), PG_reserved,1);
+	//ret = register_chrdev (0, KBUILD_MODNAME, &ldt_fops);
 	if (pdev) {
 		data = pdev->dev.platform_data;
 		r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
@@ -241,6 +300,14 @@ static int __devexit ldt_remove(struct platform_device *pdev)
 	if (irq) {
 		free_irq(irq, THIS_MODULE);
 	}
+	if (in_buf) {
+		pages_flag(virt_to_page(in_buf), PFN_UP(bufsize), PG_reserved,0);
+		free_pages_exact(in_buf, bufsize);
+	}
+	if (out_buf) {
+		pages_flag(virt_to_page(out_buf), PFN_UP(bufsize), PG_reserved,0);
+		free_pages_exact(out_buf, bufsize);
+	}
 	trvd(isr_counter);
 	trvd(ldt_work_counter);
 	return 0;