Commit 91918ce8 authored by Hector Martin's avatar Hector Martin Committed by Kalle Valo
Browse files

wifi: brcmfmac: pcie: Provide a buffer of random bytes to the device 



Newer Apple firmwares on chipsets without a hardware RNG require the
host to provide a buffer of 256 random bytes to the device on
initialization. This buffer is present immediately before NVRAM,
suffixed by a footer containing a magic number and the buffer length.

This won't affect chips/firmwares that do not use this feature, so do it
unconditionally for all Apple platforms (those with an Apple OTP).

Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarHector Martin <marcan@marcan.st>
Reviewed-by: default avatarJulian Calaby <julian.calaby@gmail.com>
Signed-off-by: default avatarKalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230214080034.3828-3-marcan@marcan.st
parent 0f485805

drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c

+32 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/sched/signal.h>

#include <linux/kthread.h>

#include <linux/io.h>

#include <linux/random.h>

#include <asm/unaligned.h>



#include <soc.h>
@@ -1653,6 +1654,13 @@ brcmf_pcie_init_share_ram_info(struct brcmf_pciedev_info *devinfo, 
	return 0;

}



struct brcmf_random_seed_footer {

	__le32 length;

	__le32 magic;

};



#define BRCMF_RANDOM_SEED_MAGIC		0xfeedc0de

#define BRCMF_RANDOM_SEED_LENGTH	0x100



static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,

					const struct firmware *fw, void *nvram,
@@ -1689,6 +1697,30 @@ static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo, 
			  nvram_len;

		memcpy_toio(devinfo->tcm + address, nvram, nvram_len);

		brcmf_fw_nvram_free(nvram);



		if (devinfo->otp.valid) {

			size_t rand_len = BRCMF_RANDOM_SEED_LENGTH;

			struct brcmf_random_seed_footer footer = {

				.length = cpu_to_le32(rand_len),

				.magic = cpu_to_le32(BRCMF_RANDOM_SEED_MAGIC),

			};

			void *randbuf;



			/* Some Apple chips/firmwares expect a buffer of random

			 * data to be present before NVRAM

			 */

			brcmf_dbg(PCIE, "Download random seed\n");



			address -= sizeof(footer);

			memcpy_toio(devinfo->tcm + address, &footer,

				    sizeof(footer));



			address -= rand_len;

			randbuf = kzalloc(rand_len, GFP_KERNEL);

			get_random_bytes(randbuf, rand_len);

			memcpy_toio(devinfo->tcm + address, randbuf, rand_len);

			kfree(randbuf);

		}

	} else {

		brcmf_dbg(PCIE, "No matching NVRAM file found %s\n",

			  devinfo->nvram_name);