examples: file_serving: add support for ESP32-S3, refactoring

* Move filesystem mounting code into a separate file to simplify the
  main source file.
* Clean up SDMMC and SDSPI related code. Move pin configuration into
  Kconfig.
* Use same base_path ('/data') for either SPIFFS or SD. Remove the
  check in file_server.c about the base path.
* Update README according to the changes above.

examples/protocols/http_server/file_serving/main/mount.c

@@ -0,0 +1,160 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+/* HTTP File Server Example, SD card / SPIFFS mount functions.
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include "esp_log.h"
+#include "esp_err.h"
+#include "esp_vfs_fat.h"
+#include "esp_spiffs.h"
+#include "sdkconfig.h"
+#include "soc/soc_caps.h"
+#include "driver/sdspi_host.h"
+#include "driver/spi_common.h"
+#if SOC_SDMMC_HOST_SUPPORTED
+#include "driver/sdmmc_host.h"
+#endif
+#include "sdmmc_cmd.h"
+#include "file_serving_example_common.h"
+
+static const char *TAG = "example_mount";
+
+#ifdef CONFIG_EXAMPLE_MOUNT_SD_CARD
+
+esp_err_t example_mount_storage(const char* base_path)
+{
+    ESP_LOGI(TAG, "Initializing SD card");
+
+    esp_vfs_fat_sdmmc_mount_config_t mount_config = {
+#ifdef CONFIG_EXAMPLE_FORMAT_IF_MOUNT_SDCARD_FAILED
+        .format_if_mount_failed = true,
+#else
+        .format_if_mount_failed = false,
+#endif // CONFIG_EXAMPLE_FORMAT_IF_MOUNT_SDCARD_FAILED
+        .max_files = 5,
+        .allocation_unit_size = 16 * 1024
+    };
+    esp_err_t ret;
+    sdmmc_card_t* card;
+
+#ifdef CONFIG_EXAMPLE_USE_SDMMC_HOST
+    ESP_LOGI(TAG, "Using SDMMC peripheral");
+    sdmmc_host_t host = SDMMC_HOST_DEFAULT();
+
+    // This initializes the slot without card detect (CD) and write protect (WP) signals.
+    // Modify slot_config.gpio_cd and slot_config.gpio_wp if your board has these signals.
+    sdmmc_slot_config_t slot_config = SDMMC_SLOT_CONFIG_DEFAULT();
+
+    // To use 1-line SD mode, change this to 1:
+    slot_config.width = 4;
+
+#ifdef SOC_SDMMC_USE_GPIO_MATRIX
+    // For chips which support GPIO Matrix for SDMMC peripheral, specify the pins.
+    slot_config.clk = CONFIG_EXAMPLE_PIN_CLK;
+    slot_config.cmd = CONFIG_EXAMPLE_PIN_CMD;
+    slot_config.d0 = CONFIG_EXAMPLE_PIN_D0;
+    slot_config.d1 = CONFIG_EXAMPLE_PIN_D1;
+    slot_config.d2 = CONFIG_EXAMPLE_PIN_D2;
+    slot_config.d3 = CONFIG_EXAMPLE_PIN_D3;
+#endif // SOC_SDMMC_USE_GPIO_MATRIX
+
+    // Enable internal pullups on enabled pins. The internal pullups
+    // are insufficient however, please make sure 10k external pullups are
+    // connected on the bus. This is for debug / example purpose only.
+    slot_config.flags |= SDMMC_SLOT_FLAG_INTERNAL_PULLUP;
+
+    ret = esp_vfs_fat_sdmmc_mount(base_path, &host, &slot_config, &mount_config, &card);
+
+#else // CONFIG_EXAMPLE_USE_SDMMC_HOST
+
+    ESP_LOGI(TAG, "Using SPI peripheral");
+
+    sdmmc_host_t host = SDSPI_HOST_DEFAULT();
+    spi_bus_config_t bus_cfg = {
+        .mosi_io_num = CONFIG_EXAMPLE_PIN_MOSI,
+        .miso_io_num = CONFIG_EXAMPLE_PIN_MISO,
+        .sclk_io_num = CONFIG_EXAMPLE_PIN_CLK,
+        .quadwp_io_num = -1,
+        .quadhd_io_num = -1,
+        .max_transfer_sz = 4000,
+    };
+
+    ret = spi_bus_initialize(host.slot, &bus_cfg, SDSPI_DEFAULT_DMA);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to initialize bus.");
+        return ret;
+    }
+
+    // This initializes the slot without card detect (CD) and write protect (WP) signals.
+    // Modify slot_config.gpio_cd and slot_config.gpio_wp if your board has these signals.
+    sdspi_device_config_t slot_config = SDSPI_DEVICE_CONFIG_DEFAULT();
+    slot_config.gpio_cs = CONFIG_EXAMPLE_PIN_CS;
+    slot_config.host_id = host.slot;
+    ret = esp_vfs_fat_sdspi_mount(base_path, &host, &slot_config, &mount_config, &card);
+
+#endif // !CONFIG_EXAMPLE_USE_SDMMC_HOST
+
+    if (ret != ESP_OK){
+        if (ret == ESP_FAIL) {
+            ESP_LOGE(TAG, "Failed to mount filesystem. "
+                "If you want the card to be formatted, set the EXAMPLE_FORMAT_IF_MOUNT_FAILED menuconfig option.");
+        } else {
+            ESP_LOGE(TAG, "Failed to initialize the card (%s). "
+                "Make sure SD card lines have pull-up resistors in place.", esp_err_to_name(ret));
+        }
+        return ret;
+    }
+
+    sdmmc_card_print_info(stdout, card);
+    return ESP_OK;
+}
+
+#else // CONFIG_EXAMPLE_MOUNT_SD_CARD
+
+/* Function to initialize SPIFFS */
+esp_err_t example_mount_storage(const char* base_path)
+{
+    ESP_LOGI(TAG, "Initializing SPIFFS");
+
+    esp_vfs_spiffs_conf_t conf = {
+        .base_path = base_path,
+        .partition_label = NULL,
+        .max_files = 5,   // This sets the maximum number of files that can be open at the same time
+        .format_if_mount_failed = true
+    };
+
+    esp_err_t ret = esp_vfs_spiffs_register(&conf);
+    if (ret != ESP_OK) {
+        if (ret == ESP_FAIL) {
+            ESP_LOGE(TAG, "Failed to mount or format filesystem");
+        } else if (ret == ESP_ERR_NOT_FOUND) {
+            ESP_LOGE(TAG, "Failed to find SPIFFS partition");
+        } else {
+            ESP_LOGE(TAG, "Failed to initialize SPIFFS (%s)", esp_err_to_name(ret));
+        }
+        return ret;
+    }
+
+    size_t total = 0, used = 0;
+    ret = esp_spiffs_info(NULL, &total, &used);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to get SPIFFS partition information (%s)", esp_err_to_name(ret));
+        return ret;
+    }
+
+    ESP_LOGI(TAG, "Partition size: total: %d, used: %d", total, used);
+    return ESP_OK;
+}
+
+#endif // !CONFIG_EXAMPLE_MOUNT_SD_CARD