Le Tue, Sep 21, 2021 at 11:39:27PM +0200, Emmanuel Gil Peyrot a écrit :

This engine implements AES in CBC mode, using 128-bit keys only.  It is
present on both the Wii and the Wii U, and is apparently identical in
both consoles.

The hardware is capable of firing an interrupt when the operation is
done, but this driver currently uses a busy loop, I’m not too sure
whether it would be preferable to switch, nor how to achieve that.

It also supports a mode where no operation is done, and thus could be
used as a DMA copy engine, but I don’t know how to expose that to the
kernel or whether it would even be useful.

In my testing, on a Wii U, this driver reaches 80.7 MiB/s, while the
aes-generic driver only reaches 30.9 MiB/s, so it is a quite welcome
speedup.

This driver was written based on reversed documentation, see:
https://wiibrew.org/wiki/Hardware/AES

Signed-off-by: Emmanuel Gil Peyrot <redacted>
Tested-by: Emmanuel Gil Peyrot <redacted>  # on Wii U

[...]

+static int
+do_crypt(const void *src, void *dst, u32 len, u32 flags)
+{
+	u32 blocks = ((len >> 4) - 1) & AES_CTRL_BLOCK;
+	u32 status;
+	u32 counter = OP_TIMEOUT;
+	u32 i;
+
+	/* Flush out all of src, we can’t know whether any of it is in cache */
+	for (i = 0; i < len; i += 32)
+		__asm__("dcbf 0, %0" : : "r" (src + i));
+	__asm__("sync" : : : "memory");
+
+	/* Set the addresses for DMA */
+	iowrite32be(virt_to_phys((void *)src), base + AES_SRC);
+	iowrite32be(virt_to_phys(dst), base + AES_DEST);

Hello

Since you do DMA operation, I think you should use the DMA-API and call dma_map_xxx()
This will prevent the use of __asm__ and virt_to_phys().

Regards