c07e1f20dc
Most fbdev drivers depend on framebuffer_alloc() to initialize the allocated memory to 0. Document this guarantee. v3: * slightly reword the sentence (Miguel) Suggested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn> Cc: Helge Deller <deller@gmx.de> Link: https://patchwork.freedesktop.org/patch/msgid/20230715185343.7193-19-tzimmermann@suse.de
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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#include <linux/export.h>
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#include <linux/fb.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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/**
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* framebuffer_alloc - creates a new frame buffer info structure
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*
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* @size: size of driver private data, can be zero
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* @dev: pointer to the device for this fb, this can be NULL
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*
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* Creates a new frame buffer info structure. Also reserves @size bytes
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* for driver private data (info->par). info->par (if any) will be
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* aligned to sizeof(long). The new instances of struct fb_info and
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* the driver private data are both cleared to zero.
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*
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* Returns the new structure, or NULL if an error occurred.
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*
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*/
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struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
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{
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#define BYTES_PER_LONG (BITS_PER_LONG/8)
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#define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))
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int fb_info_size = sizeof(struct fb_info);
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struct fb_info *info;
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char *p;
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if (size)
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fb_info_size += PADDING;
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p = kzalloc(fb_info_size + size, GFP_KERNEL);
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if (!p)
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return NULL;
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info = (struct fb_info *) p;
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if (size)
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info->par = p + fb_info_size;
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info->device = dev;
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info->fbcon_rotate_hint = -1;
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#if IS_ENABLED(CONFIG_FB_BACKLIGHT)
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mutex_init(&info->bl_curve_mutex);
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#endif
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return info;
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#undef PADDING
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#undef BYTES_PER_LONG
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}
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EXPORT_SYMBOL(framebuffer_alloc);
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/**
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* framebuffer_release - marks the structure available for freeing
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*
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* @info: frame buffer info structure
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*
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* Drop the reference count of the device embedded in the
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* framebuffer info structure.
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*
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*/
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void framebuffer_release(struct fb_info *info)
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{
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if (!info)
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return;
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if (WARN_ON(refcount_read(&info->count)))
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return;
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#if IS_ENABLED(CONFIG_FB_BACKLIGHT)
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mutex_destroy(&info->bl_curve_mutex);
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#endif
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kfree(info);
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}
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EXPORT_SYMBOL(framebuffer_release);
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