iwlwifi: support SAR GEO Offset Mapping override via BIOS

Support reading the SAR Geographic Offset Mapping (SGOM) table from UEFI
to allow OEMs to override the values according to geographical regions.

Signed-off-by: Ayala Barazani <ayala.barazani@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211204174546.e6dfd8b5dd40.Ibc9a8fe2bfde345f49df5d57ec56663da6a53dc4@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/fw/uefi.c b/drivers/net/wireless/intel/iwlwifi/fw/uefi.c
index c875bf35533c..c4dfc1aa60d5 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/uefi.c
+++ b/drivers/net/wireless/intel/iwlwifi/fw/uefi.c
@@ -11,6 +11,7 @@
 #include "fw/uefi.h"
 #include "fw/api/alive.h"
 #include <linux/efi.h>
+#include "fw/runtime.h"
 
 #define IWL_EFI_VAR_GUID EFI_GUID(0x92daaf2f, 0xc02b, 0x455b,	\
 				  0xb2, 0xec, 0xf5, 0xa3,	\
@@ -260,3 +261,90 @@ out:
 
 	return data;
 }
+
+#ifdef CONFIG_ACPI
+static int iwl_uefi_sgom_parse(struct uefi_cnv_wlan_sgom_data *sgom_data,
+			       struct iwl_fw_runtime *fwrt)
+{
+	int i, j;
+
+	if (sgom_data->revision != 1)
+		return -EINVAL;
+
+	memcpy(fwrt->sgom_table.offset_map, sgom_data->offset_map,
+	       sizeof(fwrt->sgom_table.offset_map));
+
+	for (i = 0; i < MCC_TO_SAR_OFFSET_TABLE_ROW_SIZE; i++) {
+		for (j = 0; j < MCC_TO_SAR_OFFSET_TABLE_COL_SIZE; j++) {
+			/* since each byte is composed of to values, */
+			/* one for each letter, */
+			/* extract and check each of them separately */
+			u8 value = fwrt->sgom_table.offset_map[i][j];
+			u8 low = value & 0xF;
+			u8 high = (value & 0xF0) >> 4;
+
+			if (high > fwrt->geo_num_profiles)
+				high = 0;
+			if (low > fwrt->geo_num_profiles)
+				low = 0;
+			fwrt->sgom_table.offset_map[i][j] = (high << 4) | low;
+		}
+	}
+
+	fwrt->sgom_enabled = true;
+	return 0;
+}
+
+void iwl_uefi_get_sgom_table(struct iwl_trans *trans,
+			     struct iwl_fw_runtime *fwrt)
+{
+	struct efivar_entry *sgom_efivar;
+	struct uefi_cnv_wlan_sgom_data *data;
+	unsigned long package_size;
+	int err, ret;
+
+	if (!fwrt->geo_enabled)
+		return;
+
+	sgom_efivar = kzalloc(sizeof(*sgom_efivar), GFP_KERNEL);
+	if (!sgom_efivar)
+		return;
+
+	memcpy(&sgom_efivar->var.VariableName, IWL_UEFI_SGOM_NAME,
+	       sizeof(IWL_UEFI_SGOM_NAME));
+	sgom_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_SGOM_SIZE;
+
+	data = kmalloc(package_size, GFP_KERNEL);
+	if (!data) {
+		data = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	err = efivar_entry_get(sgom_efivar, NULL, &package_size, data);
+	if (err) {
+		IWL_DEBUG_FW(trans,
+			     "SGOM UEFI variable not found %d\n", err);
+		goto out_free;
+	}
+
+	IWL_DEBUG_FW(trans, "Read SGOM from UEFI with size %lu\n",
+		     package_size);
+
+	ret = iwl_uefi_sgom_parse(data, fwrt);
+	if (ret < 0)
+		IWL_DEBUG_FW(trans, "Cannot read SGOM tables. rev is invalid\n");
+
+out_free:
+	kfree(data);
+
+out:
+	kfree(sgom_efivar);
+}
+IWL_EXPORT_SYMBOL(iwl_uefi_get_sgom_table);
+#endif /* CONFIG_ACPI */