spi: fixed crash when calling spi_bus_free when not initialized

introduced in 49a48644e4

Closes: https://github.com/espressif/esp-idf/issues/8642

components/driver/include/driver/spi_common.h

@@ -159,7 +159,7 @@ esp_err_t spi_bus_initialize(spi_host_device_t host_id, const spi_bus_config_t *
  * @param host_id SPI peripheral to free
  * @return
  *         - ESP_ERR_INVALID_ARG   if parameter is invalid
- *         - ESP_ERR_INVALID_STATE if not all devices on the bus are freed
+ *         - ESP_ERR_INVALID_STATE if bus hasn't been initialized before, or not all devices on the bus are freed
  *         - ESP_OK                on success
  */
 esp_err_t spi_bus_free(spi_host_device_t host_id);

components/driver/spi_common.c

@@ -862,6 +862,10 @@ const spi_bus_attr_t* spi_bus_get_attr(spi_host_device_t host_id)
 
 esp_err_t spi_bus_free(spi_host_device_t host_id)
 {
+    if (bus_ctx[host_id] == NULL) {
+        return ESP_ERR_INVALID_STATE;
+    }
+
     esp_err_t err = ESP_OK;
     spicommon_bus_context_t* ctx = bus_ctx[host_id];
     spi_bus_attr_t* bus_attr = &ctx->bus_attr;