rfid: add boot-time MFRC522 VersionReg probe over SPI3 to definitively diagnose MISO/power vs reset-path

main/rfid_manager.c

@@ -72,12 +72,47 @@ static void on_picc_state_changed(void *arg, esp_event_base_t base, int32_t even
     }
 }
 
+/* Read the MFRC522 VersionReg (0x37) directly over SPI3 with a temporary
+ * hardware-CS device. Any plausible value (0x88/0x91/0x92) means the chip is
+ * alive and MISO works; 0x00/0xFF means MISO/power/wiring is dead. This is a
+ * pure diagnostic and does not depend on the rc522 driver's reset path. */
+static void rfid_probe_version(void)
+{
+    spi_device_handle_t probe = NULL;
+    spi_device_interface_config_t devcfg = {
+        .clock_speed_hz = RC522_SPI_CLK_HZ,
+        .mode = 0,
+        .spics_io_num = HW_RC522_CS_GPIO,
+        .queue_size = 1,
+        .command_bits = 1,   /* read/write select bit */
+        .address_bits = 6,   /* register address */
+        .dummy_bits = 1,
+    };
+    if (spi_bus_add_device(HW_RFID_SPI_HOST, &devcfg, &probe) != ESP_OK || probe == NULL) {
+        ESP_LOGW(TAG, "probe: could not add temp SPI device on SPI3");
+        return;
+    }
+
+    uint8_t version = 0;
+    spi_transaction_t t = {
+        .cmd = 1,          /* read */
+        .addr = 0x37,      /* VersionReg */
+        .rxlength = 8,
+        .rx_buffer = &version,
+    };
+    esp_err_t ret = spi_device_polling_transmit(probe, &t);
+    ESP_LOGI(TAG, "MFRC522 VersionReg=0x%02X (%s). 0x88/0x91/0x92=alive; 0x00/0xFF=MISO/power/wiring",
+             version, esp_err_to_name(ret));
+
+    spi_bus_remove_device(probe);
+}
+
 esp_err_t rfid_manager_init(void)
 {
     /* Dedicated SPI3_HOST (HSPI) bus for the reader - independent controller
-     * so the display (SPI2_HOST) and the RFID never share bus timing. The
+     * so the display (SPI2_HOST) and the RFID never share bus timing. We
-     * rc522 driver will call spi_bus_initialize() itself on this host with
+     * initialize SPI3 here (with a real MISO) and hand the already-initialized
-     * this bus config (MISO=13 is a real pin and is used for reads). */
+     * bus to the rc522 driver via bus_config=NULL so it only adds its device. */
     static spi_bus_config_t rfid_bus_cfg = {
         .sclk_io_num = HW_RFID_SCK_GPIO,
         .mosi_io_num = HW_RFID_MOSI_GPIO,
@@ -88,9 +123,17 @@ esp_err_t rfid_manager_init(void)
     ESP_LOGI(TAG, "initializing MFRC522 on SPI3_HOST (SCK=%d MOSI=%d MISO=%d CS=%d)",
              HW_RFID_SCK_GPIO, HW_RFID_MOSI_GPIO, HW_RFID_MISO_GPIO, HW_RC522_CS_GPIO);
 
+    esp_err_t ret = spi_bus_initialize(HW_RFID_SPI_HOST, &rfid_bus_cfg, SPI_DMA_CH_AUTO);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "spi_bus_initialize(SPI3) failed: %s", esp_err_to_name(ret));
+        return ret;
+    }
+
+    rfid_probe_version();
+
     rc522_spi_config_t driver_config = {
         .host_id = HW_RFID_SPI_HOST,
-        .bus_config = &rfid_bus_cfg,
+        .bus_config = NULL,   /* SPI3 already initialized above */
         .dev_config = {
             .spics_io_num = HW_RC522_CS_GPIO,
             .clock_speed_hz = RC522_SPI_CLK_HZ,
@@ -102,15 +145,14 @@ esp_err_t rfid_manager_init(void)
         .rst_io_num = -1,
     };
 
-    esp_err_t ret = rc522_spi_create(&driver_config, &s_driver);
+    ret = rc522_spi_create(&driver_config, &s_driver);
     if (ret != ESP_OK) {
         ESP_LOGE(TAG, "rc522_spi_create failed: %s", esp_err_to_name(ret));
         return ret;
     }
     ret = rc522_driver_install(s_driver);
     if (ret != ESP_OK) {
-        /* Includes the SPI3 bus initialization; never abort boot here. */
+        ESP_LOGE(TAG, "rc522 driver install failed: %s", esp_err_to_name(ret));
-        ESP_LOGE(TAG, "rc522 driver install (incl. SPI3 bus init) failed: %s", esp_err_to_name(ret));
         return ret;
     }