...
+#ifdef __ARM__ +extern void memcpy32(void *, void *, size_t);
+static void *memcpy(void *dest, const void *src, size_t count) +{
- if (count < 32) {
unsigned short *_s = (unsigned short *)(src);unsigned short *_d = (unsigned short *)(dest);count >>= 1;while (count--)*_d++ = *_s++;return _d;- }
- memcpy32(dest, (void *)src, count);
- return (void *)count;
+} +#endif
Why exactly do we need this? And why do we need an additonal special function memcpy32?
It's for performance. Now ARM used the char-based memcpy. Even though it's working with current char-based memcpy, I want to use the optimized memcpy. And basically OneNAND uses the 16-bit buswidth so we don't sure the correct behavior in OneNAND BufferRAM if we use the char-based memcpy.
Memcpy32 is 32-bytes aligned optimized. Since we know the memcpy usages in OneNAND driver, we guarantee the usage of memcpy32.
+static const unsigned char ffchars[] = {
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 16 */
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 32 */
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 48 */
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 64 */
+};
Using a dynamic buffer and a memset() call in the init code may helpt to reduce the memory footprint. What do you think?
At first I want to sync between the linux OneNAND code and u-boot one. The current code of u-boot patch is the first implementation of linux OneNAND. There are a lot of works to sync. So after committing of patches, I will modify it.
+static unsigned short onenand_readw(void __iomem * addr) +{
- return readw(addr);
+}
...
+static void onenand_writew(unsigned short value, void __iomem * addr) +{
- writew(value, addr);
+}
If this is all you do, you should probably use an inline or a macro.
It's same reason as above. In linux OneNAND, we can overwrite the readw and writew. But I'm now sure it's needed at u-boot. if (!this->read_word) this->read_word = onenand_readw; if (!this->write_word) this->write_word = onenand_writew;
- Get the device and lock it for exclusive access
- */
+static void onenand_get_device(struct mtd_info *mtd, int new_state) +{
- /* Do nothing */
+}
...
- Deselect, release chip lock and wake up anyone waiting on the device
- */
+static void onenand_release_device(struct mtd_info *mtd) +{
- /* Do nothing */
+}
Inline? Macro?
Also others are same. Some functions are don't needed at u-boot. But it was remained for easy adaptation from linux to u-boot.
Thank you, Kyungmin Park