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.
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
---
.../broadcom/brcm80211/brcmfmac/pcie.c | 30 +++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
index cc76f00724e6..a8cccfbea20b 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
@@ -12,6 +12,7 @@
#include <linux/interrupt.h>
#include <linux/bcma/bcma.h>
#include <linux/sched.h>
+#include <linux/random.h>
#include <asm/unaligned.h>
#include <soc.h>
@@ -1662,6 +1663,13 @@ 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,
@@ -1693,11 +1701,33 @@ static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,
brcmf_pcie_write_ram32(devinfo, devinfo->ci->ramsize - 4, 0);
if (nvram) {
+ 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;
+
brcmf_dbg(PCIE, "Download NVRAM %s\n", devinfo->nvram_name);
address = devinfo->ci->rambase + devinfo->ci->ramsize -
nvram_len;
brcmf_pcie_copy_mem_todev(devinfo, address, nvram, nvram_len);
brcmf_fw_nvram_free(nvram);
+
+ /* 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);
+ brcmf_pcie_copy_mem_todev(devinfo, address, &footer,
+ sizeof(footer));
+
+ address -= rand_len;
+ randbuf = kzalloc(rand_len, GFP_KERNEL);
+ get_random_bytes(randbuf, rand_len);
+ brcmf_pcie_copy_mem_todev(devinfo, address, randbuf, rand_len);
+ kfree(randbuf);
} else {
brcmf_dbg(PCIE, "No matching NVRAM file found %s\n",
devinfo->nvram_name);
--
2.33.0
