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* [RFC 2.6.20 1/1] fbdev,mm: Deferred IO and hecubafb driver
@ 2007-02-23  6:32 Jaya Kumar
  2007-02-23  9:22 ` Paul Mundt
  2007-02-24  6:51 ` [Linux-fbdev-devel] [RFC 2.6.20 1/1] fbdev, mm: " Antonino A. Daplas
  0 siblings, 2 replies; 5+ messages in thread
From: Jaya Kumar @ 2007-02-23  6:32 UTC (permalink / raw)
  To: linux-fbdev-devel, linux-kernel, linux-mm

Hi Tony, Paul, Peter, fbdev, lkml, and mm,

This is a first pass at abstracting deferred IO out from hecubafb and
into fbdev as was discussed before: 
http://marc.theaimsgroup.com/?l=linux-fbdev-devel&m=117187443327466&w=2

Please let me know your feedback and if it looks okay so far.

Thanks,
jaya

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>

---

 Documentation/fb/deferred_io.txt |  114 ++++++++
 drivers/video/Kconfig            |   20 +
 drivers/video/Makefile           |    2 
 drivers/video/fb_defio.c         |  104 +++++++
 drivers/video/fbmem.c            |    2 
 drivers/video/hecubafb.c         |  513 +++++++++++++++++++++++++++++++++++++++
 include/linux/fb.h               |   25 +
 mm/rmap.c                        |    1 
 8 files changed, 781 insertions(+)

diff --git a/Documentation/fb/deferred_io.txt b/Documentation/fb/deferred_io.txt
new file mode 100644
index 0000000..be74dcc
--- /dev/null
+++ b/Documentation/fb/deferred_io.txt
@@ -0,0 +1,114 @@
+Deferred IO
+-----------
+
+Deferred IO is a way to delay and repurpose IO. It uses host memory as a
+buffer and the MMU pagefault as a pretrigger for when to perform the device
+IO. The following example may be a useful explaination of how one such setup
+works:
+
+- userspace app like Xfbdev mmaps framebuffer
+- deferred IO and driver sets up nopage and page_mkwrite handlers
+- userspace app tries to write to mmaped vaddress
+- we get pagefault and reach nopage handler
+- nopage handler finds and returns physical page
+- we get page_mkwrite where we add this page to a list
+- schedule a workqueue task to be run after a delay
+- app continues writing to that page with no additional cost. this is
+  the key benefit.
+- the workqueue task comes in and mkcleans the pages on the list, then
+ completes the work associated with updating the framebuffer. this is
+  the real work talking to the device.
+- app tries to write to the address (that has now been mkcleaned)
+- get pagefault and the above sequence occurs again
+
+As can be seen from above, one benefit is roughly to allow bursty framebuffer
+writes to occur at minimum cost. Then after some time when hopefully things
+have gone quiet, we go and really update the framebuffer which would be
+a relatively more expensive operation.
+
+For some types of nonvolatile high latency displays, the desired image is
+the final image rather than the intermediate stages which is why it's okay
+to not update for each write that is occuring.
+
+It may be the case that this is useful in other scenarios as well. Paul Mundt
+has mentioned a case where it is beneficial to use the page count to decide
+whether to coalesce and issue SG DMA or to do memory bursts.
+
+Another one may be if one has a device framebuffer that is in an usual format,
+say diagonally shifting RGB, this may then be a mechanism for you to allow
+apps to pretend to have a normal framebuffer but reswizzle for the device
+framebuffer at vsync time based on the touched pagelist.
+
+How to use it: (for applications)
+---------------------------------
+No changes needed. mmap the framebuffer like normal and just use it.
+
+How to use it: (for fbdev drivers)
+----------------------------------
+The following example may be helpful.
+
+1. Setup your mmap and vm_ops structures. Eg:
+
+static struct fb_deferred_io hecubafb_defio = {
+	.delay		= HZ,
+	.deferred_io	= hecubafb_dpy_deferred_io,
+};
+
+The delay is the minimum delay between when the page_mkwrite trigger occurs
+and when the deferred_io callback is called. The deferred_io callback is
+explained below.
+
+static struct vm_operations_struct hecubafb_vm_ops = {
+	.nopage   	= hecubafb_vm_nopage,
+	.page_mkwrite	= fb_deferred_io_mkwrite,
+};
+
+You will need a nopage routine to find and retrive the struct page for your
+framebuffer pages. You must set page_mkwrite to fb_deferred_io_mkwrite.
+Here's the example nopage for hecubafb where it is a vmalloced framebuffer. 
+
+static int hecubafb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &hecubafb_vm_ops;
+	vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
+	vma->vm_private_data = info;
+	return 0;
+}
+
+static struct page* hecubafb_vm_nopage(struct vm_area_struct *vma, 
+					unsigned long vaddr, int *type)
+{
+	unsigned long offset;
+	struct page *page;
+	struct fb_info *info = vma->vm_private_data;
+
+	offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
+	if (offset >= (DPY_W*DPY_H)/8)
+		return NOPAGE_SIGBUS;
+
+	page = vmalloc_to_page(info->screen_base + offset);
+	if (!page)
+		return NOPAGE_OOM;
+
+	get_page(page);
+	if (type)
+		*type = VM_FAULT_MINOR;
+	return page;
+}
+
+2. Setup your deferred IO callback. Eg:
+static void hecubafb_dpy_deferred_io(struct fb_info *info,
+				struct list_head *pagelist)
+
+The deferred_io callback is where you would perform all your IO to the display
+device. You receive the pagelist which is the list of pages that were written
+to during the delay. You must not modify this list. This callback is called
+from a workqueue. 
+
+3. Call init (done inside register_framebuffer)
+	info->fbdefio = &hecubafb_defio;
+
+	retval = register_framebuffer(info);
+
+4. Call cleanup (done inside unregister_framebuffer)
+		unregister_framebuffer(info);
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 8874cf2..a03c772 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -85,6 +85,12 @@ config FB_CFB_IMAGEBLIT
 	  blitting. This is used by drivers that don't provide their own
 	  (accelerated) version.
 
+# used by hecubafb
+config FB_DEFERRED_IO
+	bool
+	depends on FB
+	default n
+
 config FB_SVGALIB
 	tristate
 	depends on FB
@@ -540,6 +546,20 @@ config FB_IMAC
 	help
 	  This is the frame buffer device driver for the Intel-based Macintosh
 
+config FB_HECUBA
+	tristate "Hecuba board support"
+	depends on FB && X86 && MMU
+	select FB_CFB_FILLRECT
+	select FB_CFB_COPYAREA
+	select FB_CFB_IMAGEBLIT
+	select FB_DEFERRED_IO
+	help
+	  This enables support for the Hecuba board. This driver was tested 
+	  with an E-Ink 800x600 display and x86 SBCs through a 16 bit GPIO
+	  interface (8 bit data, 4 bit control). If you anticpate using
+	  this driver, say Y or M; otherwise say N. You must specify the
+	  GPIO IO address to be used for setting control and data.
+
 config FB_HGA
 	tristate "Hercules mono graphics support"
 	depends on FB && X86
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 6801edf..c36a323 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_FB_CFB_IMAGEBLIT) += cfbimgblt.o
 obj-$(CONFIG_FB_SVGALIB)       += svgalib.o
 obj-$(CONFIG_FB_MACMODES)      += macmodes.o
 obj-$(CONFIG_FB_DDC)           += fb_ddc.o
+obj-$(CONFIG_FB_DEFERRED_IO)   += fb_defio.o
 
 # Hardware specific drivers go first
 obj-$(CONFIG_FB_AMIGA)            += amifb.o c2p.o
@@ -65,6 +66,7 @@ obj-$(CONFIG_FB_SGIVW)            += sgivwfb.o
 obj-$(CONFIG_FB_ACORN)            += acornfb.o
 obj-$(CONFIG_FB_ATARI)            += atafb.o
 obj-$(CONFIG_FB_MAC)              += macfb.o
+obj-$(CONFIG_FB_HECUBA)           += hecubafb.o
 obj-$(CONFIG_FB_HGA)              += hgafb.o
 obj-$(CONFIG_FB_IGA)              += igafb.o
 obj-$(CONFIG_FB_APOLLO)           += dnfb.o
diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
new file mode 100644
index 0000000..c3e57cc
--- /dev/null
+++ b/drivers/video/fb_defio.c
@@ -0,0 +1,104 @@
+/*
+ *  linux/drivers/video/fb_defio.c
+ *
+ *  Copyright (C) 2006 Jaya Kumar
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/fb.h>
+#include <linux/list.h>
+#include <asm/uaccess.h>
+
+/* to support deferred IO */
+#include <linux/rmap.h>
+#include <linux/pagemap.h>
+
+/* workqueue callback */
+static void fb_deferred_io_work(struct work_struct *work)
+{
+	struct fb_info *info = container_of(work, struct fb_info, 
+						deferred_work.work);
+	struct list_head *node, *next;
+	struct page *cur;
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	/* here we mkclean the pages, then do all deferred IO */
+	mutex_lock(&fbdefio->lock);
+	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
+		lock_page(cur);
+		page_mkclean(cur);
+		unlock_page(cur);
+	}
+
+	/* driver's callback with pagelist */
+	fbdefio->deferred_io(info, &fbdefio->pagelist); 
+
+	/* clear the list */
+	list_for_each_safe(node, next, &fbdefio->pagelist) {
+		list_del(node);
+	}
+	mutex_unlock(&fbdefio->lock);
+}
+
+/* vm_ops->page_mkwrite handler */
+int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 
+					struct page *page)
+{
+	struct fb_info *info = vma->vm_private_data;
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	/* this is a callback we get when userspace first tries to 
+	write to the page. we schedule a workqueue. that workqueue 
+	will eventually mkclean the touched pages and execute the 
+	deferred framebuffer IO. then if userspace touches a page 
+	again, we repeat the same scheme */
+
+	/* protect against the workqueue changing the page list */
+	mutex_lock(&fbdefio->lock);
+	list_add(&page->lru, &fbdefio->pagelist);
+	mutex_unlock(&fbdefio->lock);
+
+	/* come back after delay to process the deferred IO */
+	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_mkwrite);
+
+void fb_deferred_io_init(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	if (!fbdefio)
+		return;
+	mutex_init(&fbdefio->lock);
+	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
+	INIT_LIST_HEAD(&fbdefio->pagelist);
+	if (fbdefio->delay == 0) /* set a default of 1 s */
+		fbdefio->delay = HZ;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_init);
+
+void fb_deferred_io_cleanup(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	if (!fbdefio)
+		return;
+	cancel_delayed_work(&info->deferred_work);
+	flush_scheduled_work();
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 2822526..863126a 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1325,6 +1325,7 @@ register_framebuffer(struct fb_info *fb_info)
 
 	event.info = fb_info;
 	fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
+	fb_deferred_io_init(fb_info);
 	return 0;
 }
 
@@ -1355,6 +1356,7 @@ unregister_framebuffer(struct fb_info *fb_info)
 	fb_destroy_modelist(&fb_info->modelist);
 	registered_fb[i]=NULL;
 	num_registered_fb--;
+	fb_deferred_io_cleanup(fb_info);
 	fb_cleanup_device(fb_info);
 	device_destroy(fb_class, MKDEV(FB_MAJOR, i));
 	event.info = fb_info;
diff --git a/drivers/video/hecubafb.c b/drivers/video/hecubafb.c
new file mode 100644
index 0000000..519659a
--- /dev/null
+++ b/drivers/video/hecubafb.c
@@ -0,0 +1,513 @@
+/*
+ * linux/drivers/video/hecubafb.c -- FB driver for Hecuba controller
+ *
+ * Copyright (C) 2006, Jaya Kumar 
+ * This work was sponsored by CIS(M) Sdn Bhd
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of this archive for
+ * more details.
+ *
+ * Layout is based on skeletonfb.c by James Simmons and Geert Uytterhoeven.
+ * This work was possible because of apollo display code from E-Ink's website
+ * http://support.eink.com/community
+ * All information used to write this code is from public material made
+ * available by E-Ink on its support site. Some commands such as 0xA4
+ * were found by looping through cmd=0x00 thru 0xFF and supplying random
+ * values. There are other commands that the display is capable of,
+ * beyond the 5 used here but they are more complex. 
+ *
+ * This driver is written to be used with the Hecuba display controller
+ * board, and tested with the EInk 800x600 display in 1 bit mode. 
+ * The interface between Hecuba and the host is TTL based GPIO. The
+ * GPIO requirements are 8 writable data lines and 6 lines for control.
+ * Only 4 of the controls are actually used here but 6 for future use.
+ * The driver requires the IO addresses for data and control GPIO at 
+ * load time. It is also possible to use this display with a standard 
+ * PC parallel port. 
+ *
+ * General notes:
+ * - User must set hecubafb_enable=1 to enable it
+ * - User must set dio_addr=0xIOADDR cio_addr=0xIOADDR c2io_addr=0xIOADDR
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/fb.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/list.h>
+#include <asm/uaccess.h>
+
+/* Apollo controller specific defines */
+#define APOLLO_START_NEW_IMG	0xA0
+#define APOLLO_STOP_IMG_DATA	0xA1
+#define APOLLO_DISPLAY_IMG	0xA2
+#define APOLLO_ERASE_DISPLAY	0xA3
+#define APOLLO_INIT_DISPLAY	0xA4
+
+/* Hecuba interface specific defines */
+/* WUP is inverted, CD is inverted, DS is inverted */
+#define HCB_NWUP_BIT	0x01
+#define HCB_NDS_BIT 	0x02
+#define HCB_RW_BIT 	0x04
+#define HCB_NCD_BIT 	0x08
+#define HCB_ACK_BIT 	0x80
+
+/* Display specific information */
+#define DPY_W 600
+#define DPY_H 800
+
+struct hecubafb_par {
+	unsigned long dio_addr;
+	unsigned long cio_addr;
+	unsigned long c2io_addr;
+	unsigned char ctl;
+	struct fb_info *info;
+	unsigned int irq;
+};
+
+static struct fb_fix_screeninfo hecubafb_fix __initdata = {
+	.id =		"hecubafb",
+	.type =		FB_TYPE_PACKED_PIXELS,
+	.visual =	FB_VISUAL_MONO01,
+	.xpanstep =	0,
+	.ypanstep =	0,
+	.ywrapstep =	0,
+	.accel =	FB_ACCEL_NONE,
+};
+
+static struct fb_var_screeninfo hecubafb_var __initdata = {
+	.xres		= DPY_W,
+	.yres		= DPY_H,
+	.xres_virtual	= DPY_W,
+	.yres_virtual	= DPY_H,
+	.bits_per_pixel	= 1,
+	.nonstd		= 1,
+};
+
+static unsigned long dio_addr;
+static unsigned long cio_addr;
+static unsigned long c2io_addr;
+static unsigned long splashval;
+static unsigned int nosplash;
+static unsigned int hecubafb_enable;
+static unsigned int irq;
+
+static DECLARE_WAIT_QUEUE_HEAD(hecubafb_waitq);
+
+static void hcb_set_ctl(struct hecubafb_par *par)
+{
+	outb(par->ctl, par->cio_addr);
+}
+
+static unsigned char hcb_get_ctl(struct hecubafb_par *par)
+{
+	return inb(par->c2io_addr);
+}
+
+static void hcb_set_data(struct hecubafb_par *par, unsigned char value)
+{
+	outb(value, par->dio_addr);
+}
+
+static int __devinit apollo_init_control(struct hecubafb_par *par)
+{
+	unsigned char ctl;
+	/* for init, we want the following setup to be set:
+	WUP = lo
+	ACK = hi
+	DS = hi
+	RW = hi
+	CD = lo 
+	*/
+
+	/* write WUP to lo, DS to hi, RW to hi, CD to lo */
+	par->ctl = HCB_NWUP_BIT | HCB_RW_BIT | HCB_NCD_BIT ;
+	par->ctl &= ~HCB_NDS_BIT;
+	hcb_set_ctl(par);
+
+	/* check ACK is not lo */
+	ctl = hcb_get_ctl(par);
+	if ((ctl & HCB_ACK_BIT)) {
+		printk(KERN_ERR "Fail because ACK is already low\n");
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+void hcb_wait_for_ack(struct hecubafb_par *par)
+{
+
+	int timeout;
+	unsigned char ctl;
+
+	timeout=500;
+	do {
+		ctl = hcb_get_ctl(par);
+		if ((ctl & HCB_ACK_BIT)) 
+			return;
+		udelay(1);
+	} while (timeout--);
+	printk(KERN_ERR "timed out waiting for ack\n");
+}
+
+void hcb_wait_for_ack_clear(struct hecubafb_par *par)
+{
+
+	int timeout;
+	unsigned char ctl;
+
+	timeout=500;
+	do {
+		ctl = hcb_get_ctl(par);
+		if (!(ctl & HCB_ACK_BIT)) 
+			return;
+		udelay(1);
+	} while (timeout--);
+	printk(KERN_ERR "timed out waiting for clear\n");
+}
+
+void apollo_send_data(struct hecubafb_par *par, unsigned char data)
+{
+	/* set data */
+	hcb_set_data(par, data);
+
+	/* set DS low */
+	par->ctl |= HCB_NDS_BIT;
+	hcb_set_ctl(par);
+
+	hcb_wait_for_ack(par);
+
+	/* set DS hi */
+	par->ctl &= ~(HCB_NDS_BIT);
+	hcb_set_ctl(par);
+	
+	hcb_wait_for_ack_clear(par);
+}
+
+void apollo_send_command(struct hecubafb_par *par, unsigned char data)
+{
+	/* command so set CD to high */
+	par->ctl &= ~(HCB_NCD_BIT);
+	hcb_set_ctl(par);
+
+	/* actually strobe with command */
+	apollo_send_data(par, data);
+
+	/* clear CD back to low */
+	par->ctl |= (HCB_NCD_BIT);
+	hcb_set_ctl(par);
+}
+
+/* main hecubafb functions */
+
+static void hecubafb_dpy_update(struct hecubafb_par *par)
+{
+	int i;
+	unsigned char *buf = par->info->screen_base;
+
+	apollo_send_command(par, 0xA0);
+
+	for (i=0; i < (DPY_W*DPY_H/8); i++) {
+		apollo_send_data(par, *(buf++));
+	}
+
+	apollo_send_command(par, 0xA1);
+	apollo_send_command(par, 0xA2);
+}
+
+/* this is called back from the deferred io workqueue */
+static void hecubafb_dpy_deferred_io(struct fb_info *info, 
+				struct list_head *pagelist)
+{
+	hecubafb_dpy_update(info->par);
+}
+
+static void hecubafb_fillrect(struct fb_info *info,
+				   const struct fb_fillrect *rect)
+{
+	struct hecubafb_par *par = info->par;
+
+	cfb_fillrect(info, rect);
+
+	hecubafb_dpy_update(par);
+}
+
+static void hecubafb_copyarea(struct fb_info *info,
+				   const struct fb_copyarea *area)
+{
+	struct hecubafb_par *par = info->par;
+
+	cfb_copyarea(info, area);
+
+	hecubafb_dpy_update(par);
+}
+
+static void hecubafb_imageblit(struct fb_info *info, 
+				const struct fb_image *image)
+{
+	struct hecubafb_par *par = info->par;
+
+	cfb_imageblit(info, image);
+
+	hecubafb_dpy_update(par);
+}
+
+/*
+ * this is the slow path from userspace. they can seek and write to
+ * the fb. it's inefficient to do anything less than a full screen draw 
+ */
+static ssize_t hecubafb_write(struct file *file, const char __user *buf, 
+				size_t count, loff_t *ppos)
+{
+	struct inode *inode;
+	int fbidx;
+	struct fb_info *info;
+	unsigned long p;
+	int err=-EINVAL;
+	struct hecubafb_par *par;
+	unsigned int xres;
+	unsigned int fbmemlength;
+
+	p = *ppos;
+	inode = file->f_dentry->d_inode;
+	fbidx = iminor(inode);
+	info = registered_fb[fbidx];
+
+	if (!info || !info->screen_base)
+		return -ENODEV;
+
+	par = info->par;
+	xres = info->var.xres;
+	fbmemlength = (xres * info->var.yres)/8;
+
+	if (p > fbmemlength)
+		return -ENOSPC;
+
+	err = 0;
+	if ((count + p) > fbmemlength) {
+		count = fbmemlength - p;
+		err = -ENOSPC;
+	}
+
+	if (count) {
+		char *base_addr;
+
+		base_addr = info->screen_base;
+		count -= copy_from_user(base_addr + p, buf, count);
+		*ppos += count;
+		err = -EFAULT;
+	}
+
+	hecubafb_dpy_update(par);
+
+	if (count)
+		return count;
+
+	return err;
+}
+
+/* this is to find and return the vmalloc-ed fb pages */
+static struct page* hecubafb_vm_nopage(struct vm_area_struct *vma, 
+					unsigned long vaddr, int *type)
+{
+	unsigned long offset;
+	struct page *page;
+	struct fb_info *info = vma->vm_private_data;
+
+	offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
+	if (offset >= (DPY_W*DPY_H)/8)
+		return NOPAGE_SIGBUS;
+
+	page = vmalloc_to_page(info->screen_base + offset);
+	if (!page)
+		return NOPAGE_OOM;
+
+	get_page(page);
+	if (type)
+		*type = VM_FAULT_MINOR;
+	return page;
+}
+
+static struct vm_operations_struct hecubafb_vm_ops = {
+	.nopage   	= hecubafb_vm_nopage,
+	.page_mkwrite	= fb_deferred_io_mkwrite,
+};
+
+static int hecubafb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &hecubafb_vm_ops;
+	vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
+	vma->vm_private_data = info;
+	return 0;
+}
+
+static struct fb_ops hecubafb_ops = {
+	.owner		= THIS_MODULE,
+	.fb_write	= hecubafb_write,
+	.fb_fillrect	= hecubafb_fillrect,
+	.fb_copyarea	= hecubafb_copyarea,
+	.fb_imageblit	= hecubafb_imageblit,
+	.fb_mmap	= hecubafb_mmap,
+};
+
+static struct fb_deferred_io hecubafb_defio = {
+	.delay		= HZ,
+	.deferred_io	= hecubafb_dpy_deferred_io,
+};
+
+static int __devinit hecubafb_probe(struct platform_device *dev)
+{
+	struct fb_info *info;
+	int retval = -ENOMEM;
+	int videomemorysize;
+	unsigned char *videomemory;
+	struct hecubafb_par *par;
+
+	videomemorysize = (DPY_W*DPY_H)/8;
+
+	if (!(videomemory = vmalloc(videomemorysize)))
+		return retval;
+
+	memset(videomemory, 0, videomemorysize);
+
+	info = framebuffer_alloc(sizeof(struct hecubafb_par), &dev->dev);
+	if (!info)
+		goto err;
+
+	info->screen_base = (char __iomem *) videomemory;
+	info->fbops = &hecubafb_ops;
+
+	info->var = hecubafb_var;
+	info->fix = hecubafb_fix;
+	par = info->par;
+	par->info = info;
+
+	if (!dio_addr || !cio_addr || !c2io_addr) {
+		printk(KERN_WARNING "no IO addresses supplied\n");
+		goto err1;
+	}
+	par->dio_addr = dio_addr;
+	par->cio_addr = cio_addr;
+	par->c2io_addr = c2io_addr;
+	info->flags = FBINFO_FLAG_DEFAULT;
+
+	info->fbdefio = &hecubafb_defio;
+
+	retval = register_framebuffer(info);
+	if (retval < 0)
+		goto err1;
+	platform_set_drvdata(dev, info);
+
+	printk(KERN_INFO
+	       "fb%d: Hecuba frame buffer device, using %dK of video memory\n",
+	       info->node, videomemorysize >> 10);
+
+	/* this inits the dpy */
+	apollo_init_control(par);
+
+	apollo_send_command(par, APOLLO_INIT_DISPLAY);
+	apollo_send_data(par, 0x81);
+
+	/* have to wait while display resets */
+	udelay(1000);
+
+	/* if we were told to splash the screen, we just clear it */
+	if (!nosplash) {
+		apollo_send_command(par, APOLLO_ERASE_DISPLAY);
+		apollo_send_data(par, splashval);
+	}
+
+	return 0;
+err1:
+	framebuffer_release(info);
+err:
+	vfree(videomemory);
+	return retval;
+}
+
+static int __devexit hecubafb_remove(struct platform_device *dev)
+{
+	struct fb_info *info = platform_get_drvdata(dev);
+
+	if (info) {
+		unregister_framebuffer(info);
+		vfree(info->screen_base);
+		framebuffer_release(info);
+	}
+	return 0;
+}
+
+static struct platform_driver hecubafb_driver = {
+	.probe	= hecubafb_probe,
+	.remove = hecubafb_remove,
+	.driver	= {
+		.name	= "hecubafb",
+	},
+};
+
+static struct platform_device *hecubafb_device;
+
+static int __init hecubafb_init(void)
+{
+	int ret;
+
+	if (!hecubafb_enable) {
+		printk(KERN_ERR "Use hecubafb_enable to enable the device\n");
+		return -ENXIO;
+	}
+
+	ret = platform_driver_register(&hecubafb_driver);
+	if (!ret) {
+		hecubafb_device = platform_device_alloc("hecubafb", 0);
+		if (hecubafb_device) 
+			ret = platform_device_add(hecubafb_device);
+		else 
+			ret = -ENOMEM;
+
+		if (ret) {
+			platform_device_put(hecubafb_device);
+			platform_driver_unregister(&hecubafb_driver);
+		}
+	}
+	return ret;
+
+}
+
+static void __exit hecubafb_exit(void)
+{
+	platform_device_unregister(hecubafb_device);
+	platform_driver_unregister(&hecubafb_driver);
+}
+
+module_param(nosplash, uint, 0);
+MODULE_PARM_DESC(nosplash, "Disable doing the splash screen");
+module_param(hecubafb_enable, uint, 0);
+MODULE_PARM_DESC(hecubafb_enable, "Enable communication with Hecuba board");
+module_param(dio_addr, ulong, 0);
+MODULE_PARM_DESC(dio_addr, "IO address for data, eg: 0x480");
+module_param(cio_addr, ulong, 0);
+MODULE_PARM_DESC(cio_addr, "IO address for control, eg: 0x400");
+module_param(c2io_addr, ulong, 0);
+MODULE_PARM_DESC(c2io_addr, "IO address for secondary control, eg: 0x408");
+module_param(splashval, ulong, 0);
+MODULE_PARM_DESC(splashval, "Splash pattern: 0x00 is black, 0x01 is white");
+module_param(irq, uint, 0);
+MODULE_PARM_DESC(irq, "IRQ for the Hecuba board");
+
+module_init(hecubafb_init);
+module_exit(hecubafb_exit);
+
+MODULE_DESCRIPTION("fbdev driver for Hecuba board");
+MODULE_AUTHOR("Jaya Kumar");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/fb.h b/include/linux/fb.h
index a78e256..88a6c53 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -559,6 +559,16 @@ struct fb_pixmap {
 	void (*readio) (struct fb_info *info, void *dst, void __iomem *src, unsigned int size);
 };
 
+#ifdef CONFIG_FB_DEFERRED_IO
+struct fb_deferred_io {
+	/* delay between mkwrite and deferred handler */
+	unsigned long delay;	
+	struct mutex lock; /* mutex that protects the page list */
+	struct list_head pagelist; /* list of touched pages */
+	/* callback */
+	void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);
+};
+#endif
 
 /*
  * Frame buffer operations
@@ -779,6 +789,10 @@ struct fb_info {
 	/* Backlight level curve */
 	u8 bl_curve[FB_BACKLIGHT_LEVELS];
 #endif
+#ifdef CONFIG_FB_DEFERRED_IO
+	struct delayed_work deferred_work;
+	struct fb_deferred_io *fbdefio;
+#endif
 
 	struct fb_ops *fbops;
 	struct device *device;		/* This is the parent */
@@ -914,6 +928,17 @@ static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch,
 	}
 }
 
+#ifdef CONFIG_FB_DEFERRED_IO
+/* drivers/video/fb_defio.c */
+extern void fb_deferred_io_init(struct fb_info *info);
+extern void fb_deferred_io_cleanup(struct fb_info *info);
+extern int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 
+					struct page *page);
+#else
+#define fb_deferred_io_init(fb_info)	do { } while (0)
+#define fb_deferred_io_cleanup(fb_info)	do { } while (0)
+#endif
+
 /* drivers/video/fbsysfs.c */
 extern struct fb_info *framebuffer_alloc(size_t size, struct device *dev);
 extern void framebuffer_release(struct fb_info *info);
diff --git a/mm/rmap.c b/mm/rmap.c
index 669acb2..0fa0521 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -496,6 +496,7 @@ int page_mkclean(struct page *page)
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(page_mkclean);
 
 /**
  * page_set_anon_rmap - setup new anonymous rmap

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [RFC 2.6.20 1/1] fbdev,mm: Deferred IO and hecubafb driver
  2007-02-23  6:32 [RFC 2.6.20 1/1] fbdev,mm: Deferred IO and hecubafb driver Jaya Kumar
@ 2007-02-23  9:22 ` Paul Mundt
  2007-02-24  8:24   ` Jaya Kumar
  2007-02-24  6:51 ` [Linux-fbdev-devel] [RFC 2.6.20 1/1] fbdev, mm: " Antonino A. Daplas
  1 sibling, 1 reply; 5+ messages in thread
From: Paul Mundt @ 2007-02-23  9:22 UTC (permalink / raw)
  To: Jaya Kumar; +Cc: linux-fbdev-devel, linux-kernel, linux-mm

On Fri, Feb 23, 2007 at 07:32:28AM +0100, Jaya Kumar wrote:
> This is a first pass at abstracting deferred IO out from hecubafb and
> into fbdev as was discussed before: 
> http://marc.theaimsgroup.com/?l=linux-fbdev-devel&m=117187443327466&w=2
> 
> Please let me know your feedback and if it looks okay so far.
> 
How about this for an fsync()? I wonder if this will be sufficient for
msync() based flushing, or whether the ->sync VMA op is needed again..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

--

 drivers/video/fb_defio.c |   12 ++++++++++++
 drivers/video/fbmem.c    |    3 +++
 include/linux/fb.h       |    2 ++
 3 files changed, 17 insertions(+)

diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
index c3e57cc..8a66dc8 100644
--- a/drivers/video/fb_defio.c
+++ b/drivers/video/fb_defio.c
@@ -52,6 +52,18 @@ static void fb_deferred_io_work(struct work_struct *work)
 	mutex_unlock(&fbdefio->lock);
 }
 
+int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+	struct fb_info *info = file->private_data;
+
+	/* Kill off the delayed work */
+	cancel_rearming_delayed_work(&info->deferred_work);
+
+	/* Run it immediately */
+	return schedule_delayed_work(&info->deferred_work, 0);
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
+
 /* vm_ops->page_mkwrite handler */
 int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 
 					struct page *page)
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 863126a..69bbbe2 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1266,6 +1266,9 @@ static const struct file_operations fb_fops = {
 #ifdef HAVE_ARCH_FB_UNMAPPED_AREA
 	.get_unmapped_area = get_fb_unmapped_area,
 #endif
+#ifdef CONFIG_FB_DEFERRED_IO
+	.fsync =	fb_deferred_io_fsync,
+#endif
 };
 
 struct class *fb_class;
diff --git a/include/linux/fb.h b/include/linux/fb.h
index af217dd..3f62652 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -933,6 +933,8 @@ extern void fb_deferred_io_init(struct fb_info *info);
 extern void fb_deferred_io_cleanup(struct fb_info *info);
 extern int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 
 					struct page *page);
+extern int fb_deferred_io_fsync(struct file *file, struct dentry *dentry,
+				int datasync);
 #else
 #define fb_deferred_io_init(fb_info)	do { } while (0)
 #define fb_deferred_io_cleanup(fb_info)	do { } while (0)

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [Linux-fbdev-devel] [RFC 2.6.20 1/1] fbdev, mm: Deferred IO and hecubafb driver
  2007-02-23  6:32 [RFC 2.6.20 1/1] fbdev,mm: Deferred IO and hecubafb driver Jaya Kumar
  2007-02-23  9:22 ` Paul Mundt
@ 2007-02-24  6:51 ` Antonino A. Daplas
  2007-02-24  8:14   ` Jaya Kumar
  1 sibling, 1 reply; 5+ messages in thread
From: Antonino A. Daplas @ 2007-02-24  6:51 UTC (permalink / raw)
  To: linux-fbdev-devel, Jaya Kumar; +Cc: linux-kernel, linux-mm

On Fri, 2007-02-23 at 07:32 +0100, Jaya Kumar wrote:
> Hi Tony, Paul, Peter, fbdev, lkml, and mm,
> 
> This is a first pass at abstracting deferred IO out from hecubafb and
> into fbdev as was discussed before: 
> http://marc.theaimsgroup.com/?l=linux-fbdev-devel&m=117187443327466&w=2
> 
> Please let me know your feedback and if it looks okay so far.
> 

Can you create 2 separate patches, one for the deferred_io and another
for the driver that uses it?

> +Another one may be if one has a device framebuffer that is in an usual format,
> +say diagonally shifting RGB, this may then be a mechanism for you to allow
> +apps to pretend to have a normal framebuffer but reswizzle for the device
> +framebuffer at vsync time based on the touched pagelist.

Hmm, yes, it can be used to implement a shadow framebuffer :-)

> +
> +How to use it: (for applications)
> +---------------------------------
> +No changes needed. mmap the framebuffer like normal and just use it.
> +
> +How to use it: (for fbdev drivers)
> +----------------------------------
> +The following example may be helpful.
> +
> +1. Setup your mmap and vm_ops structures. Eg:
> +
> +
> +The delay is the minimum delay between when the page_mkwrite trigger occurs
> +and when the deferred_io callback is called. The deferred_io callback is
> +explained below.
> +
> +static struct vm_operations_struct hecubafb_vm_ops = {
> +	.nopage   	= hecubafb_vm_nopage,
> +	.page_mkwrite	= fb_deferred_io_mkwrite,
> +};
> +

It would seem to me that the above can be made generic, so we have this
instead:

static struct vm_operations_struct fb_deferred_vm_ops = {
	.nopage   	= fb_deferred_io_vm_nopage,
	.page_mkwrite	= fb_deferred_io_mkwrite,
};

> +You will need a nopage routine to find and retrive the struct page for your
> +framebuffer pages. You must set page_mkwrite to fb_deferred_io_mkwrite.
> +Here's the example nopage for hecubafb where it is a vmalloced framebuffer. 
> +
> +static int hecubafb_mmap(struct fb_info *info, struct vm_area_struct *vma)
> +{
> +	vma->vm_ops = &hecubafb_vm_ops;
> +	vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
> +	vma->vm_private_data = info;
> +	return 0;
> +}

And this too as fb_deferred_io_mmap.

> +
> +static struct page* hecubafb_vm_nopage(struct vm_area_struct *vma, 
> +					unsigned long vaddr, int *type)
> +{
> +	unsigned long offset;
> +	struct page *page;
> +	struct fb_info *info = vma->vm_private_data;
> +
> +	offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
> +	if (offset >= (DPY_W*DPY_H)/8)
> +		return NOPAGE_SIGBUS;
> +

To make it generic, this can simply be:

	if (offset >= info->fix.smem_len)
		return NOPAGE_SIGBUS.

> +	page = vmalloc_to_page(info->screen_base + offset);
> +	if (!page)
> +		return NOPAGE_OOM;
> +
> +	get_page(page);
> +	if (type)
> +		*type = VM_FAULT_MINOR;
> +	return page;
> +}
> +
> 

> +static struct fb_deferred_io hecubafb_defio = {
> +	.delay		= HZ,
> +	.deferred_io	= hecubafb_dpy_deferred_io,
> +};

Leaving the drivers to just fill up the above. This would result in a
decrease of code duplication and it will be easier for driver writers.


> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index 2822526..863126a 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1325,6 +1325,7 @@ register_framebuffer(struct fb_info *fb_info)
>  
>  	event.info = fb_info;
>  	fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
> +	fb_deferred_io_init(fb_info);
>  	return 0;
>  }
>  
> @@ -1355,6 +1356,7 @@ unregister_framebuffer(struct fb_info *fb_info)
>  	fb_destroy_modelist(&fb_info->modelist);
>  	registered_fb[i]=NULL;
>  	num_registered_fb--;
> +	fb_deferred_io_cleanup(fb_info);
>  	fb_cleanup_device(fb_info);
>  	device_destroy(fb_class, MKDEV(FB_MAJOR, i));
>  	event.info = fb_info;

I would prefer to have the init and cleanup functions called by the
driver themselves, instead of piggy-backing them to the
framebuffer_register/unregister.


> +static void hecubafb_dpy_update(struct hecubafb_par *par)
> +{
> +	int i;
> +	unsigned char *buf = par->info->screen_base;
> +
> +	apollo_send_command(par, 0xA0);
> +
> +	for (i=0; i < (DPY_W*DPY_H/8); i++) {
> +		apollo_send_data(par, *(buf++));
> +	}
> +

This basically dumps the entire framebuffer to the hardware, doesn't it?
This framebuffer has only 2 pages at the most, so it doesn't matter. But
for hardware with MB's of RAM, I don't think this is feasible.

Is there a way to selectively update only the touched pages, ie from the
fbdevio->pagelist? struct page has a field (pgoff_t index), is this
usable? If not, can we just create a bit array, just to tell the driver
which are the dirty pages?

Tony


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [Linux-fbdev-devel] [RFC 2.6.20 1/1] fbdev, mm: Deferred IO and hecubafb driver
  2007-02-24  6:51 ` [Linux-fbdev-devel] [RFC 2.6.20 1/1] fbdev, mm: " Antonino A. Daplas
@ 2007-02-24  8:14   ` Jaya Kumar
  0 siblings, 0 replies; 5+ messages in thread
From: Jaya Kumar @ 2007-02-24  8:14 UTC (permalink / raw)
  To: Antonino A. Daplas; +Cc: linux-fbdev-devel, linux-kernel, linux-mm

On 2/24/07, Antonino A. Daplas <adaplas@gmail.com> wrote:
> On Fri, 2007-02-23 at 07:32 +0100, Jaya Kumar wrote:
> Can you create 2 separate patches, one for the deferred_io and another
> for the driver that uses it?

Will do.

> > +static struct vm_operations_struct hecubafb_vm_ops = {
> > +     .nopage         = hecubafb_vm_nopage,
> > +     .page_mkwrite   = fb_deferred_io_mkwrite,
> > +};
> > +
>
> It would seem to me that the above can be made generic, so we have this
> instead:

We could. But I think fb_deferred_io_vm_nopage would then have to
handle the different types or possible combinations of framebuffer
allocations, if they kmalloced or vmalloced or maybe combinations. Ok.
I'll try to implement that. Maybe we'll need a flag where the driver
informs us of the type of allocation.

>
> > +static struct fb_deferred_io hecubafb_defio = {
> > +     .delay          = HZ,
> > +     .deferred_io    = hecubafb_dpy_deferred_io,
> > +};
>
> Leaving the drivers to just fill up the above. This would result in a
> decrease of code duplication and it will be easier for driver writers.

I agree it'll be much cleaner that way but was worried if having
fb_defio do that would prevent driver writers from having their own
nopage and controlling other vm related functionality. Looking at
drivers/video/* shows no one touching vm_ops, so I guess we'll be
fine. If fb_defio takes ownership of the driver's nopage, vm_ops, etc,
then it could be just the above struct and the
fb_deferred_io_init/cleanup functions that are exposed to the driver.
ie: if an fbdev driver calls fb_deferred_io_init, we setup their mmap,
vm_ops and the necessary bits. I'll give that a shot.

>
> I would prefer to have the init and cleanup functions called by the
> driver themselves, instead of piggy-backing them to the
> framebuffer_register/unregister.
>

Understood. I had done it that way originally but changed just before
posting. I'll revert back. :)

> This basically dumps the entire framebuffer to the hardware, doesn't it?
> This framebuffer has only 2 pages at the most, so it doesn't matter. But
> for hardware with MB's of RAM, I don't think this is feasible.

Yup, hecuba doesn't have clean partial update functionality. But the
callback exposed to drivers is:

+       void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);

which gives the drivers the list of dirty pages in pagelist. So other
drivers for hardware with the right capabilities can implement
selective or partial updates. As you mentioned, I imagine that the
drivers internally could have a bit array to enable them to mark and
find sequential partial updates. I would leave the page bitmap for
drivers to do since it would be specific to their hardware.

Thanks,
jaya

>
> Is there a way to selectively update only the touched pages, ie from the
> fbdevio->pagelist? struct page has a field (pgoff_t index), is this
> usable? If not, can we just create a bit array, just to tell the driver
> which are the dirty pages?
>
> Tony
>
>

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [RFC 2.6.20 1/1] fbdev,mm: Deferred IO and hecubafb driver
  2007-02-23  9:22 ` Paul Mundt
@ 2007-02-24  8:24   ` Jaya Kumar
  0 siblings, 0 replies; 5+ messages in thread
From: Jaya Kumar @ 2007-02-24  8:24 UTC (permalink / raw)
  To: Paul Mundt, Jaya Kumar, linux-fbdev-devel, linux-kernel, linux-mm

On 2/23/07, Paul Mundt <lethal@linux-sh.org> wrote:
> On Fri, Feb 23, 2007 at 07:32:28AM +0100, Jaya Kumar wrote:
> > This is a first pass at abstracting deferred IO out from hecubafb and
> > into fbdev as was discussed before:
> > http://marc.theaimsgroup.com/?l=linux-fbdev-devel&m=117187443327466&w=2
> >
> > Please let me know your feedback and if it looks okay so far.
> >
> How about this for an fsync()? I wonder if this will be sufficient for
> msync() based flushing, or whether the ->sync VMA op is needed again..
>

Looks fine to me.

Thanks,
jaya

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2007-02-24  8:24 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-02-23  6:32 [RFC 2.6.20 1/1] fbdev,mm: Deferred IO and hecubafb driver Jaya Kumar
2007-02-23  9:22 ` Paul Mundt
2007-02-24  8:24   ` Jaya Kumar
2007-02-24  6:51 ` [Linux-fbdev-devel] [RFC 2.6.20 1/1] fbdev, mm: " Antonino A. Daplas
2007-02-24  8:14   ` Jaya Kumar

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