Improvements in EspClass (#222)

* Improvements in EspClass

- fixed not working functions for flash chip size, speed and mode
- added function to retrieve chip revision from eFuse
- flashRead / flashWrite supports encrypted flash

* Rename getCpuRevision function to getChipRevision

* Revert: flashRead / flashWrite supports encrypted flash

Reading and writing to encrypted flash has to be aligned to 16-bytes. Also NAND way of writing (i.e. flipping 1s to 0s) will not work with spi_flash_write_encrypted. Note: spi_flash_read_encrypted will always try to decrypt data, even if it wasn't encrypted in the first place.

cores/esp32/Esp.cpp

@@ -23,9 +23,22 @@
 #include "esp_deep_sleep.h"
 #include "esp_spi_flash.h"
 #include <memory>
-
-//#define DEBUG_SERIAL Serial
-
+#include <soc/soc.h>
+#include <soc/efuse_reg.h>
+
+/* Main header of binary image */
+typedef struct {
+    uint8_t magic;
+    uint8_t segment_count;
+    uint8_t spi_mode;      /* flash read mode (esp_image_spi_mode_t as uint8_t) */
+    uint8_t spi_speed: 4;  /* flash frequency (esp_image_spi_freq_t as uint8_t) */
+    uint8_t spi_size: 4;   /* flash chip size (esp_image_flash_size_t as uint8_t) */
+    uint32_t entry_addr;
+    uint8_t encrypt_flag;    /* encrypt flag */
+    uint8_t extra_header[15]; /* ESP32 additional header, unused by second bootloader */
+} esp_image_header_t;
+
+#define ESP_IMAGE_HEADER_MAGIC 0xE9
 
 /**
  * User-defined Literals
@@ -104,6 +117,11 @@ uint32_t EspClass::getFreeHeap(void)
     return esp_get_free_heap_size();
 }
 
+uint8_t EspClass::getChipRevision(void)
+{
+    return (REG_READ(EFUSE_BLK0_RDATA3_REG) >> EFUSE_RD_CHIP_VER_RESERVE_S) && EFUSE_RD_CHIP_VER_RESERVE_V;
+}
+
 const char * EspClass::getSdkVersion(void)
 {
     return esp_get_idf_version();
@@ -111,57 +129,44 @@ const char * EspClass::getSdkVersion(void)
 
 uint32_t EspClass::getFlashChipSize(void)
 {
-    uint32_t data;
-    uint8_t * bytes = (uint8_t *) &data;
-    // read first 4 byte (magic byte + flash config)
-    if(flashRead(0x0000, &data, 4) == ESP_OK) {
-        return magicFlashChipSize((bytes[3] & 0xf0) >> 4);
+    esp_image_header_t fhdr;
+    if(flashRead(0x1000, (uint32_t*)&fhdr, sizeof(esp_image_header_t)) && fhdr.magic != ESP_IMAGE_HEADER_MAGIC) {
+        return 0;
     }
-    return 0;
+    return magicFlashChipSize(fhdr.spi_size);
 }
 
 uint32_t EspClass::getFlashChipSpeed(void)
 {
-    uint32_t data;
-    uint8_t * bytes = (uint8_t *) &data;
-    // read first 4 byte (magic byte + flash config)
-    if(flashRead(0x0000, &data, 4) == ESP_OK) {
-        return magicFlashChipSpeed(bytes[3] & 0x0F);
+    esp_image_header_t fhdr;
+    if(flashRead(0x1000, (uint32_t*)&fhdr, sizeof(esp_image_header_t)) && fhdr.magic != ESP_IMAGE_HEADER_MAGIC) {
+        return 0;
     }
-    return 0;
+    return magicFlashChipSpeed(fhdr.spi_speed);
 }
 
 FlashMode_t EspClass::getFlashChipMode(void)
 {
-    FlashMode_t mode = FM_UNKNOWN;
-    uint32_t data;
-    uint8_t * bytes = (uint8_t *) &data;
-    // read first 4 byte (magic byte + flash config)
-    if(flashRead(0x0000, &data, 4) == ESP_OK) {
-        mode = magicFlashChipMode(bytes[2]);
+    esp_image_header_t fhdr;
+    if(flashRead(0x1000, (uint32_t*)&fhdr, sizeof(esp_image_header_t)) && fhdr.magic != ESP_IMAGE_HEADER_MAGIC) {
+        return FM_UNKNOWN;
     }
-    return mode;
+    return magicFlashChipMode(fhdr.spi_mode);
 }
 
 uint32_t EspClass::magicFlashChipSize(uint8_t byte)
 {
     switch(byte & 0x0F) {
-    case 0x0: // 4 Mbit (512KB)
-        return (512_kB);
-    case 0x1: // 2 MBit (256KB)
-        return (256_kB);
-    case 0x2: // 8 MBit (1MB)
+    case 0x0: // 8 MBit (1MB)
         return (1_MB);
-    case 0x3: // 16 MBit (2MB)
+    case 0x1: // 16 MBit (2MB)
         return (2_MB);
-    case 0x4: // 32 MBit (4MB)
+    case 0x2: // 32 MBit (4MB)
         return (4_MB);
-    case 0x5: // 64 MBit (8MB)
+    case 0x3: // 64 MBit (8MB)
         return (8_MB);
-    case 0x6: // 128 MBit (16MB)
+    case 0x4: // 128 MBit (16MB)
         return (16_MB);
-    case 0x7: // 256 MBit (32MB)
-        return (32_MB);
     default: // fail?
         return 0;
     }
@@ -186,7 +191,7 @@ uint32_t EspClass::magicFlashChipSpeed(uint8_t byte)
 FlashMode_t EspClass::magicFlashChipMode(uint8_t byte)
 {
     FlashMode_t mode = (FlashMode_t) byte;
-    if(mode > FM_DOUT) {
+    if(mode > FM_SLOW_READ) {
         mode = FM_UNKNOWN;
     }
     return mode;
@@ -197,6 +202,7 @@ bool EspClass::flashEraseSector(uint32_t sector)
     return spi_flash_erase_sector(sector) == ESP_OK;
 }
 
+// Warning: These functions do not work with encrypted flash
 bool EspClass::flashWrite(uint32_t offset, uint32_t *data, size_t size)
 {
     return spi_flash_write(offset, (uint32_t*) data, size) == ESP_OK;

cores/esp32/Esp.h

@@ -45,6 +45,8 @@ typedef enum {
     FM_QOUT = 0x01,
     FM_DIO = 0x02,
     FM_DOUT = 0x03,
+    FM_FAST_READ = 0x04,
+    FM_SLOW_READ = 0x05,
     FM_UNKNOWN = 0xff
 } FlashMode_t;
 
@@ -55,6 +57,7 @@ public:
     ~EspClass() {}
     void restart();
     uint32_t getFreeHeap();
+    uint8_t getChipRevision();
     uint8_t getCpuFreqMHz(){ return CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ; }
     uint32_t getCycleCount();
     const char * getSdkVersion();