From 16ad24dd00ba1c9718f07deeab16b513a4eff3e4 Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Mon, 6 Apr 2020 18:27:48 +1000
Subject: [PATCH] efuse: Add an API to return the efuse descriptor for a key
 block's purpose field

---
 components/efuse/include/esp32s2/esp_efuse.h |  8 +++++++
 components/efuse/include/esp_efuse.h         | 11 +++++++---
 components/efuse/src/esp32s2/esp_efuse_api.c | 22 ++++++++++++++++++++
 3 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/components/efuse/include/esp32s2/esp_efuse.h b/components/efuse/include/esp32s2/esp_efuse.h
index 52e86e921..30dcb5e80 100644
--- a/components/efuse/include/esp32s2/esp_efuse.h
+++ b/components/efuse/include/esp32s2/esp_efuse.h
@@ -56,6 +56,14 @@ typedef enum {
     EFUSE_BLK_MAX
 } esp_efuse_block_t;
 
+struct esp_efuse_desc_s;
+
+/**
+ * @brief Given a key block in the range EFUSE_BLK_KEY0..EFUSE_BLK_KEY5, return
+ * efuse field for setting the key purpose
+ */
+const struct esp_efuse_desc_s **esp_efuse_get_purpose_field(esp_efuse_block_t block);
+
 /**
  * @brief Type of coding scheme
  */
diff --git a/components/efuse/include/esp_efuse.h b/components/efuse/include/esp_efuse.h
index aa20bf6c1..23d05712c 100644
--- a/components/efuse/include/esp_efuse.h
+++ b/components/efuse/include/esp_efuse.h
@@ -35,13 +35,18 @@ extern "C" {
 #define ESP_ERR_CODING                            (ESP_ERR_EFUSE + 0x04)      /*!< Error while a encoding operation. */
 
 /**
-* @brief Structure eFuse field
+ * @brief Structure eFuse field
  */
-typedef struct {
+struct esp_efuse_desc_s {
     esp_efuse_block_t   efuse_block: 8; /**< Block of eFuse */
     uint8_t             bit_start;      /**< Start bit [0..255] */
     uint16_t            bit_count;      /**< Length of bit field [1..-]*/
-} esp_efuse_desc_t;
+};
+
+/**
+ * @brief Type definition for an eFuse field
+ */
+typedef struct esp_efuse_desc_s esp_efuse_desc_t;
 
 /**
  * @brief   Reads bits from EFUSE field and writes it into an array.
diff --git a/components/efuse/src/esp32s2/esp_efuse_api.c b/components/efuse/src/esp32s2/esp_efuse_api.c
index 184d88338..ca15cbbcf 100644
--- a/components/efuse/src/esp32s2/esp_efuse_api.c
+++ b/components/efuse/src/esp32s2/esp_efuse_api.c
@@ -81,3 +81,25 @@ esp_efuse_coding_scheme_t esp_efuse_get_coding_scheme(esp_efuse_block_t blk)
     ESP_EARLY_LOGD(TAG, "coding scheme %d", scheme);
     return scheme;
 }
+
+
+const esp_efuse_desc_t **esp_efuse_get_purpose_field(esp_efuse_block_t block)
+{
+    switch(block) {
+    case EFUSE_BLK_KEY0:
+        return ESP_EFUSE_KEY_PURPOSE_0;
+    case EFUSE_BLK_KEY1:
+        return ESP_EFUSE_KEY_PURPOSE_1;
+    case EFUSE_BLK_KEY2:
+        return ESP_EFUSE_KEY_PURPOSE_2;
+    case EFUSE_BLK_KEY3:
+        return ESP_EFUSE_KEY_PURPOSE_3;
+    case EFUSE_BLK_KEY4:
+        return ESP_EFUSE_KEY_PURPOSE_4;
+    case EFUSE_BLK_KEY5:
+        return ESP_EFUSE_KEY_PURPOSE_5;
+    default:
+        return NULL;
+    }
+}
+