[ARM] pxafb: allow video memory size to be configurable

The amount of video memory size is decided according to the following
order:

1. <xres> x <yres> x <bits_per_pixel> by default, which is the backward
   compatible way

2. size specified in platform data

3. size specified in module parameter 'options' string or specified in
   kernel boot command line (see updated Documentation/fb/pxafb.txt)

And now since the memory is allocated from system memory, the pxafb_mmap
can be removed and the default fb_mmap() should be working all right.

Also, since we now have introduced the 'struct pxafb_dma_buff' for DMA
descriptors and palettes, the allocation can be separated cleanly.

NOTE: the LCD DMA actually supports chained transfer (i.e. page-based
transfers), to simplify the logic and keep the performance (with less
TLB misses when accessing from memory mapped user space), the memory
is allocated by alloc_pages_*() to ensures it's physical contiguous.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Eric Miao <ycmiao@ycmiao-hp520.(none)>

4 files changed, 65 insertions, 92 deletions

diff --git a/Documentation/fb/pxafb.txt b/Documentation/fb/pxafb.txt
index db9b8500b43b..ad94b5ca0095 100644
--- a/Documentation/fb/pxafb.txt
+++ b/Documentation/fb/pxafb.txt
@@ -5,9 +5,13 @@ The driver supports the following options, either via
 options=<OPTIONS> when modular or video=pxafb:<OPTIONS> when built in.
 
 For example:
-        modprobe pxafb options=mode:640x480-8,passive
+        modprobe pxafb options=vmem:2M,mode:640x480-8,passive
 or on the kernel command line
-        video=pxafb:mode:640x480-8,passive
+        video=pxafb:vmem:2M,mode:640x480-8,passive
+
+vmem: VIDEO_MEM_SIZE
+        Amount of video memory to allocate (can be suffixed with K or M
+        for kilobytes or megabytes)
 
 mode:XRESxYRES[-BPP]
         XRES == LCCR1_PPL + 1
diff --git a/arch/arm/mach-pxa/include/mach/pxafb.h b/arch/arm/mach-pxa/include/mach/pxafb.h
index 4201a889ff4e..6932720ba04e 100644
--- a/arch/arm/mach-pxa/include/mach/pxafb.h
+++ b/arch/arm/mach-pxa/include/mach/pxafb.h
@@ -113,6 +113,7 @@ struct pxafb_mach_info {
         unsigned int num_modes;
 
         unsigned int    lcd_conn;
+        unsigned long   video_mem_size;
 
         u_int           fixed_modes:1,
                         cmap_inverse:1,
diff --git a/drivers/video/pxafb.c b/drivers/video/pxafb.c
index ab689597f259..25bf4b8b6b53 100644
--- a/drivers/video/pxafb.c
+++ b/drivers/video/pxafb.c
@@ -72,6 +72,8 @@ static int pxafb_activate_var(struct fb_var_screeninfo *var,
                                 struct pxafb_info *);
 static void set_ctrlr_state(struct pxafb_info *fbi, u_int state);
 
+static unsigned long video_mem_size = 0;
+
 static inline unsigned long
 lcd_readl(struct pxafb_info *fbi, unsigned int off)
 {
@@ -498,20 +500,6 @@ static int pxafb_blank(int blank, struct fb_info *info)
         return 0;
 }
 
-static int pxafb_mmap(struct fb_info *info,
-                      struct vm_area_struct *vma)
-{
-        struct pxafb_info *fbi = (struct pxafb_info *)info;
-        unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
-
-        if (off < info->fix.smem_len) {
-                vma->vm_pgoff += fbi->video_offset / PAGE_SIZE;
-                return dma_mmap_writecombine(fbi->dev, vma, fbi->map_cpu,
-                                             fbi->map_dma, fbi->map_size);
-        }
-        return -EINVAL;
-}
-
 static struct fb_ops pxafb_ops = {
         .owner          = THIS_MODULE,
         .fb_check_var   = pxafb_check_var,
@@ -521,7 +509,6 @@ static struct fb_ops pxafb_ops = {
         .fb_copyarea    = cfb_copyarea,
         .fb_imageblit   = cfb_imageblit,
         .fb_blank       = pxafb_blank,
-        .fb_mmap        = pxafb_mmap,
 };
 
 /*
@@ -614,7 +601,7 @@ static int setup_frame_dma(struct pxafb_info *fbi, int dma, int pal,
         dma_desc = &fbi->dma_buff->dma_desc[dma];
         dma_desc_off = offsetof(struct pxafb_dma_buff, dma_desc[dma]);
 
-        dma_desc->fsadr = fbi->screen_dma + offset;
+        dma_desc->fsadr = fbi->video_mem_phys + offset;
         dma_desc->fidr  = 0;
         dma_desc->ldcmd = size;
 
@@ -1267,69 +1254,30 @@ static int pxafb_resume(struct platform_device *dev)
 #define pxafb_resume    NULL
 #endif
 
-/*
- * pxafb_map_video_memory():
- *      Allocates the DRAM memory for the frame buffer.  This buffer is
- *      remapped into a non-cached, non-buffered, memory region to
- *      allow palette and pixel writes to occur without flushing the
- *      cache.  Once this area is remapped, all virtual memory
- *      access to the video memory should occur at the new region.
- */
-static int __devinit pxafb_map_video_memory(struct pxafb_info *fbi)
+static int __devinit pxafb_init_video_memory(struct pxafb_info *fbi)
 {
-        /*
-         * We reserve one page for the palette, plus the size
-         * of the framebuffer.
-         */
-        fbi->video_offset = PAGE_ALIGN(sizeof(struct pxafb_dma_buff));
-        fbi->map_size = PAGE_ALIGN(fbi->fb.fix.smem_len + fbi->video_offset);
-        fbi->map_cpu = dma_alloc_writecombine(fbi->dev, fbi->map_size,
-                                              &fbi->map_dma, GFP_KERNEL);
-
-        if (fbi->map_cpu) {
-                /* prevent initial garbage on screen */
-                memset(fbi->map_cpu, 0, fbi->map_size);
-                fbi->fb.screen_base = fbi->map_cpu + fbi->video_offset;
-                fbi->screen_dma = fbi->map_dma + fbi->video_offset;
-
-                /*
-                 * FIXME: this is actually the wrong thing to place in
-                 * smem_start.  But fbdev suffers from the problem that
-                 * it needs an API which doesn't exist (in this case,
-                 * dma_writecombine_mmap)
-                 */
-                fbi->fb.fix.smem_start = fbi->screen_dma;
-                fbi->palette_size = fbi->fb.var.bits_per_pixel == 8 ? 256 : 16;
-
-                fbi->dma_buff = (void *) fbi->map_cpu;
-                fbi->dma_buff_phys = fbi->map_dma;
-                fbi->palette_cpu = (u16 *) fbi->dma_buff->palette;
+        int size = PAGE_ALIGN(fbi->video_mem_size);
 
-                pr_debug("pxafb: palette_mem_size = 0x%08x\n", fbi->palette_size*sizeof(u16));
-        }
-
-        return fbi->map_cpu ? 0 : -ENOMEM;
-}
+        fbi->video_mem = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+        if (fbi->video_mem == NULL)
+                return -ENOMEM;
 
-static void pxafb_decode_mode_info(struct pxafb_info *fbi,
-                                   struct pxafb_mode_info *modes,
-                                   unsigned int num_modes)
-{
-        unsigned int i, smemlen;
+        fbi->video_mem_phys = virt_to_phys(fbi->video_mem);
+        fbi->video_mem_size = size;
 
-        pxafb_setmode(&fbi->fb.var, &modes[0]);
+        fbi->fb.fix.smem_start  = fbi->video_mem_phys;
+        fbi->fb.fix.smem_len    = fbi->video_mem_size;
+        fbi->fb.screen_base     = fbi->video_mem;
 
-        for (i = 0; i < num_modes; i++) {
-                smemlen = modes[i].xres * modes[i].yres * modes[i].bpp / 8;
-                if (smemlen > fbi->fb.fix.smem_len)
-                        fbi->fb.fix.smem_len = smemlen;
-        }
+        return fbi->video_mem ? 0 : -ENOMEM;
 }
 
 static void pxafb_decode_mach_info(struct pxafb_info *fbi,
                                    struct pxafb_mach_info *inf)
 {
         unsigned int lcd_conn = inf->lcd_conn;
+        struct pxafb_mode_info *m;
+        int i;
 
         fbi->cmap_inverse       = inf->cmap_inverse;
         fbi->cmap_static        = inf->cmap_static;
@@ -1371,7 +1319,22 @@ static void pxafb_decode_mach_info(struct pxafb_info *fbi,
         fbi->lccr3 |= (lcd_conn & LCD_PCLK_EDGE_FALL)  ? LCCR3_PCP : 0;
 
 decode_mode:
-        pxafb_decode_mode_info(fbi, inf->modes, inf->num_modes);
+        pxafb_setmode(&fbi->fb.var, &inf->modes[0]);
+
+        /* decide video memory size as follows:
+         * 1. default to mode of maximum resolution
+         * 2. allow platform to override
+         * 3. allow module parameter to override
+         */
+        for (i = 0, m = &inf->modes[0]; i < inf->num_modes; i++, m++)
+                fbi->video_mem_size = max_t(size_t, fbi->video_mem_size,
+                                m->xres * m->yres * m->bpp / 8);
+
+        if (inf->video_mem_size > fbi->video_mem_size)
+                fbi->video_mem_size = inf->video_mem_size;
+
+        if (video_mem_size > fbi->video_mem_size)
+                fbi->video_mem_size = video_mem_size;
 }
 
 static struct pxafb_info * __devinit pxafb_init_fbinfo(struct device *dev)
@@ -1499,7 +1462,9 @@ static int __devinit parse_opt(struct device *dev, char *this_opt)
 
         s[0] = '\0';
 
-        if (!strncmp(this_opt, "mode:", 5)) {
+        if (!strncmp(this_opt, "vmem:", 5)) {
+                video_mem_size = memparse(this_opt + 5, NULL);
+        } else if (!strncmp(this_opt, "mode:", 5)) {
                 return parse_opt_mode(dev, this_opt);
         } else if (!strncmp(this_opt, "pixclock:", 9)) {
                 mode->pixclock = simple_strtoul(this_opt+9, NULL, 0);
@@ -1736,12 +1701,20 @@ static int __devinit pxafb_probe(struct platform_device *dev)
                 goto failed_free_res;
         }
 
-        /* Initialize video memory */
-        ret = pxafb_map_video_memory(fbi);
+        fbi->dma_buff_size = PAGE_ALIGN(sizeof(struct pxafb_dma_buff));
+        fbi->dma_buff = dma_alloc_coherent(fbi->dev, fbi->dma_buff_size,
+                                &fbi->dma_buff_phys, GFP_KERNEL);
+        if (fbi->dma_buff == NULL) {
+                dev_err(&dev->dev, "failed to allocate memory for DMA\n");
+                ret = -ENOMEM;
+                goto failed_free_io;
+        }
+
+        ret = pxafb_init_video_memory(fbi);
         if (ret) {
                 dev_err(&dev->dev, "Failed to allocate video RAM: %d\n", ret);
                 ret = -ENOMEM;
-                goto failed_free_io;
+                goto failed_free_dma;
         }
 
         irq = platform_get_irq(dev, 0);
@@ -1811,8 +1784,10 @@ failed_free_cmap:
 failed_free_irq:
         free_irq(irq, fbi);
 failed_free_mem:
-        dma_free_writecombine(&dev->dev, fbi->map_size,
-                        fbi->map_cpu, fbi->map_dma);
+        free_pages_exact(fbi->video_mem, fbi->video_mem_size);
+failed_free_dma:
+        dma_free_coherent(&dev->dev, fbi->dma_buff_size,
+                        fbi->dma_buff, fbi->dma_buff_phys);
 failed_free_io:
         iounmap(fbi->mmio_base);
 failed_free_res:
@@ -1847,8 +1822,10 @@ static int __devexit pxafb_remove(struct platform_device *dev)
         irq = platform_get_irq(dev, 0);
         free_irq(irq, fbi);
 
-        dma_free_writecombine(&dev->dev, fbi->map_size,
-                                        fbi->map_cpu, fbi->map_dma);
+        free_pages_exact(fbi->video_mem, fbi->video_mem_size);
+
+        dma_free_writecombine(&dev->dev, fbi->dma_buff_size,
+                        fbi->dma_buff, fbi->dma_buff_phys);
 
         iounmap(fbi->mmio_base);
 
diff --git a/drivers/video/pxafb.h b/drivers/video/pxafb.h
index d8eb93fa03a3..0981938682ef 100644
--- a/drivers/video/pxafb.h
+++ b/drivers/video/pxafb.h
@@ -69,24 +69,15 @@ struct pxafb_info {
         void __iomem            *mmio_base;
 
         struct pxafb_dma_buff   *dma_buff;
+        size_t                  dma_buff_size;
         dma_addr_t              dma_buff_phys;
         dma_addr_t              fdadr[DMA_MAX];
 
-        /*
-         * These are the addresses we mapped
-         * the framebuffer memory region to.
-         */
-        /* raw memory addresses */
-        dma_addr_t              map_dma;        /* physical */
-        u_char *                map_cpu;        /* virtual */
-        u_int                   map_size;
-
-        /* addresses of pieces placed in raw buffer */
-        u_char *                screen_cpu;     /* virtual address of frame buffer */
-        dma_addr_t              screen_dma;     /* physical address of frame buffer */
+        void __iomem            *video_mem;     /* virtual address of frame buffer */
+        unsigned long           video_mem_phys; /* physical address of frame buffer */
+        size_t                  video_mem_size; /* size of the frame buffer */
         u16 *                   palette_cpu;    /* virtual address of palette memory */
         u_int                   palette_size;
-        ssize_t                 video_offset;
 
         u_int                   lccr0;
         u_int                   lccr3;