iwlwifi: pnvm: implement reading PNVM from UEFI

We now support fetching the PNVM data from a UEFI variable.  Add the
code to read this variable first and use it.  If it's not available,
we fall back to reading the data from the filesystem, as before.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210211015026.289084803334.Ie234805047df3be84f4235f9dafaf4cdecf0db9a@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

diff --git a/drivers/net/wireless/intel/iwlwifi/fw/pnvm.c b/drivers/net/wireless/intel/iwlwifi/fw/pnvm.c
index d515af8..2cd07d2 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/fw/pnvm.c
+++ b/drivers/net/wireless/intel/iwlwifi/fw/pnvm.c
@@ -10,6 +10,7 @@
 #include "fw/api/commands.h"
 #include "fw/api/nvm-reg.h"
 #include "fw/api/alive.h"
+#include <linux/efi.h>
 
 struct iwl_pnvm_section {
        __le32 offset;
@@ -219,6 +220,88 @@ static int iwl_pnvm_parse(struct iwl_trans *trans, const u8 *data,
        return -ENOENT;
 }
 
+/*
+ * This is known to be broken on v4.19 and to work on v5.4.  Until we
+ * figure out why this is the case and how to make it work, simply
+ * disable the feature in old kernels.
+ */
+#if defined(CONFIG_EFI)
+
+#define IWL_EFI_VAR_GUID EFI_GUID(0x92daaf2f, 0xc02b, 0x455b,  \
+                                 0xb2, 0xec, 0xf5, 0xa3,       \
+                                 0x59, 0x4f, 0x4a, 0xea)
+
+#define IWL_UEFI_OEM_PNVM_NAME L"UefiCnvWlanOemSignedPnvm"
+
+#define IWL_HARDCODED_PNVM_SIZE 4096
+
+struct pnvm_sku_package {
+       u8 rev;
+       u8 reserved1[3];
+       u32 total_size;
+       u8 n_skus;
+       u8 reserved2[11];
+       u8 data[];
+};
+
+static int iwl_pnvm_get_from_efi(struct iwl_trans *trans,
+                                u8 **data, size_t *len)
+{
+       struct efivar_entry *pnvm_efivar;
+       struct pnvm_sku_package *package;
+       unsigned long package_size;
+       int err;
+
+       pnvm_efivar = kzalloc(sizeof(*pnvm_efivar), GFP_KERNEL);
+       if (!pnvm_efivar)
+               return -ENOMEM;
+
+       memcpy(&pnvm_efivar->var.VariableName, IWL_UEFI_OEM_PNVM_NAME,
+              sizeof(IWL_UEFI_OEM_PNVM_NAME));
+       pnvm_efivar->var.VendorGuid = IWL_EFI_VAR_GUID;
+
+       /*
+        * TODO: we hardcode a maximum length here, because reading
+        * from the UEFI is not working.  To implement this properly,
+        * we have to call efivar_entry_size().
+        */
+       package_size = IWL_HARDCODED_PNVM_SIZE;
+
+       package = kmalloc(package_size, GFP_KERNEL);
+       if (!package) {
+               err = -ENOMEM;
+               goto out;
+       }
+
+       err = efivar_entry_get(pnvm_efivar, NULL, &package_size, package);
+       if (err) {
+               IWL_DEBUG_FW(trans,
+                            "PNVM UEFI variable not found %d (len %zd)\n",
+                            err, package_size);
+               goto out;
+       }
+
+       IWL_DEBUG_FW(trans, "Read PNVM fro UEFI with size %zd\n", package_size);
+
+       *data = kmemdup(package->data, *len, GFP_KERNEL);
+       if (!*data)
+               err = -ENOMEM;
+       *len = package_size - sizeof(*package);
+
+out:
+       kfree(package);
+       kfree(pnvm_efivar);
+
+       return err;
+}
+#else /* CONFIG_EFI */
+static inline int iwl_pnvm_get_from_efi(struct iwl_trans *trans,
+                                       u8 **data, size_t *len)
+{
+       return -EOPNOTSUPP;
+}
+#endif /* CONFIG_EFI */
+
 static int iwl_pnvm_get_from_fs(struct iwl_trans *trans, u8 **data, size_t *len)
 {
        const struct firmware *pnvm;
@@ -277,7 +360,12 @@ int iwl_pnvm_load(struct iwl_trans *trans,
                goto skip_parse;
        }
 
-       /* Try to load the PNVM from the filesystem */
+       /* First attempt to get the PNVM from BIOS */
+       ret = iwl_pnvm_get_from_efi(trans, &data, &len);
+       if (!ret)
+               goto parse;
+
+       /* If it's not available, try from the filesystem */
        ret = iwl_pnvm_get_from_fs(trans, &data, &len);
        if (ret) {
                /*
@@ -290,6 +378,7 @@ int iwl_pnvm_load(struct iwl_trans *trans,
                goto skip_parse;
        }
 
+parse:
        iwl_pnvm_parse(trans, data, len);
 
        kfree(data);