ath10k: fetch (pre-)calibration data via nvmem subsystem

ATH10K chips are used it wide range of routers,
accesspoints, range extenders, network appliances.
On these embedded devices, calibration data is often
stored on the main system's flash and was out of reach
for the driver.

To bridge this gap, ath10k is getting extended to pull
the (pre-)calibration data through nvmem subsystem.
To do this, a nvmem-cell containing the information can
either be specified in the platform data or via device-tree.

Tested with:
        Netgear EX6150v2 (IPQ4018 - pre-calibration method)
        TP-Link Archer C7 v2 (QCA9880v2 - old calibration method)

Cc: Robert Marko <robimarko@gmail.com>
Cc: Thibaut VARÈNE <hacks@slashdirt.org>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211016234609.1568317-1-chunkeey@gmail.com

drivers/net/wireless/ath/ath10k/core.c

@@ -12,6 +12,7 @@
 #include <linux/dmi.h>
 #include <linux/ctype.h>
 #include <linux/pm_qos.h>
+#include <linux/nvmem-consumer.h>
 #include <asm/byteorder.h>
 
 #include "core.h"
@@ -935,7 +936,8 @@ static int ath10k_core_get_board_id_from_otp(struct ath10k *ar)
 	}
 
 	if (ar->cal_mode == ATH10K_PRE_CAL_MODE_DT ||
-	    ar->cal_mode == ATH10K_PRE_CAL_MODE_FILE)
+	    ar->cal_mode == ATH10K_PRE_CAL_MODE_FILE ||
+	    ar->cal_mode == ATH10K_PRE_CAL_MODE_NVMEM)
 		bmi_board_id_param = BMI_PARAM_GET_FLASH_BOARD_ID;
 	else
 		bmi_board_id_param = BMI_PARAM_GET_EEPROM_BOARD_ID;
@@ -1726,7 +1728,8 @@ static int ath10k_download_and_run_otp(struct ath10k *ar)
 
 	/* As of now pre-cal is valid for 10_4 variants */
 	if (ar->cal_mode == ATH10K_PRE_CAL_MODE_DT ||
-	    ar->cal_mode == ATH10K_PRE_CAL_MODE_FILE)
+	    ar->cal_mode == ATH10K_PRE_CAL_MODE_FILE ||
+	    ar->cal_mode == ATH10K_PRE_CAL_MODE_NVMEM)
 		bmi_otp_exe_param = BMI_PARAM_FLASH_SECTION_ALL;
 
 	ret = ath10k_bmi_execute(ar, address, bmi_otp_exe_param, &result);
@@ -1853,6 +1856,39 @@ static int ath10k_download_cal_eeprom(struct ath10k *ar)
 	return ret;
 }
 
+static int ath10k_download_cal_nvmem(struct ath10k *ar, const char *cell_name)
+{
+	struct nvmem_cell *cell;
+	void *buf;
+	size_t len;
+	int ret;
+
+	cell = devm_nvmem_cell_get(ar->dev, cell_name);
+	if (IS_ERR(cell)) {
+		ret = PTR_ERR(cell);
+		return ret;
+	}
+
+	buf = nvmem_cell_read(cell, &len);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	if (ar->hw_params.cal_data_len != len) {
+		kfree(buf);
+		ath10k_warn(ar, "invalid calibration data length in nvmem-cell '%s': %zu != %u\n",
+			    cell_name, len, ar->hw_params.cal_data_len);
+		return -EMSGSIZE;
+	}
+
+	ret = ath10k_download_board_data(ar, buf, len);
+	kfree(buf);
+	if (ret)
+		ath10k_warn(ar, "failed to download calibration data from nvmem-cell '%s': %d\n",
+			    cell_name, ret);
+
+	return ret;
+}
+
 int ath10k_core_fetch_firmware_api_n(struct ath10k *ar, const char *name,
 				     struct ath10k_fw_file *fw_file)
 {
@@ -2087,6 +2123,18 @@ static int ath10k_core_pre_cal_download(struct ath10k *ar)
 {
 	int ret;
 
+	ret = ath10k_download_cal_nvmem(ar, "pre-calibration");
+	if (ret == 0) {
+		ar->cal_mode = ATH10K_PRE_CAL_MODE_NVMEM;
+		goto success;
+	} else if (ret == -EPROBE_DEFER) {
+		return ret;
+	}
+
+	ath10k_dbg(ar, ATH10K_DBG_BOOT,
+		   "boot did not find a pre-calibration nvmem-cell, try file next: %d\n",
+		   ret);
+
 	ret = ath10k_download_cal_file(ar, ar->pre_cal_file);
 	if (ret == 0) {
 		ar->cal_mode = ATH10K_PRE_CAL_MODE_FILE;
@@ -2153,6 +2201,18 @@ static int ath10k_download_cal_data(struct ath10k *ar)
 		   "pre cal download procedure failed, try cal file: %d\n",
 		   ret);
 
+	ret = ath10k_download_cal_nvmem(ar, "calibration");
+	if (ret == 0) {
+		ar->cal_mode = ATH10K_CAL_MODE_NVMEM;
+		goto done;
+	} else if (ret == -EPROBE_DEFER) {
+		return ret;
+	}
+
+	ath10k_dbg(ar, ATH10K_DBG_BOOT,
+		   "boot did not find a calibration nvmem-cell, try file next: %d\n",
+		   ret);
+
 	ret = ath10k_download_cal_file(ar, ar->cal_file);
 	if (ret == 0) {
 		ar->cal_mode = ATH10K_CAL_MODE_FILE;

drivers/net/wireless/ath/ath10k/core.h

@@ -877,8 +877,10 @@ enum ath10k_cal_mode {
 	ATH10K_CAL_MODE_FILE,
 	ATH10K_CAL_MODE_OTP,
 	ATH10K_CAL_MODE_DT,
+	ATH10K_CAL_MODE_NVMEM,
 	ATH10K_PRE_CAL_MODE_FILE,
 	ATH10K_PRE_CAL_MODE_DT,
+	ATH10K_PRE_CAL_MODE_NVMEM,
 	ATH10K_CAL_MODE_EEPROM,
 };
 
@@ -898,10 +900,14 @@ static inline const char *ath10k_cal_mode_str(enum ath10k_cal_mode mode)
 		return "otp";
 	case ATH10K_CAL_MODE_DT:
 		return "dt";
+	case ATH10K_CAL_MODE_NVMEM:
+		return "nvmem";
 	case ATH10K_PRE_CAL_MODE_FILE:
 		return "pre-cal-file";
 	case ATH10K_PRE_CAL_MODE_DT:
 		return "pre-cal-dt";
+	case ATH10K_PRE_CAL_MODE_NVMEM:
+		return "pre-cal-nvmem";
 	case ATH10K_CAL_MODE_EEPROM:
 		return "eeprom";
 	}