sdm: added channel allocator for sigma delta module

components/driver/include/driver/gptimer.h

@@ -41,7 +41,7 @@ typedef bool (*gptimer_alarm_cb_t) (gptimer_handle_t timer, const gptimer_alarm_
 /**
  * @brief Group of supported GPTimer callbacks
  * @note The callbacks are all running under ISR environment
- * @note When CONFIG_GPTIMER_ISR_IRAM_SAFE is enabled, the callback itself and functions callbed by it should be placed in IRAM.
+ * @note When CONFIG_GPTIMER_ISR_IRAM_SAFE is enabled, the callback itself and functions called by it should be placed in IRAM.
  */
 typedef struct {
     gptimer_alarm_cb_t on_alarm; /*!< Timer alarm callback */

components/driver/include/driver/sdm.h

@@ -0,0 +1,111 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include "hal/sdm_types.h"
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Type of Sigma Delta channel handle
+ */
+typedef struct sdm_channel_t *sdm_channel_handle_t;
+
+/**
+ * @brief Sigma Delta channel configuration
+ */
+typedef struct {
+    int gpio_num;                    /*!< GPIO number */
+    sdm_clock_source_t clk_src; /*!< Clock source */
+    uint32_t sample_rate_hz;         /*!< Sample rate in Hz, it determines how frequent the modulator outputs a pulse */
+    struct {
+        uint32_t invert_out: 1;     /*!< Whether to invert the output signal */
+        uint32_t io_loop_back: 1;   /*!< For debug/test, the signal output from the GPIO will be fed to the input path as well */
+    } flags;                        /*!< Extra flags */
+} sdm_config_t;
+
+/**
+ * @brief Create a new Sigma Delta channel
+ *
+ * @param[in] config SDM configuration
+ * @param[out] ret_chan Returned SDM channel handle
+ * @return
+ *      - ESP_OK: Create SDM channel successfully
+ *      - ESP_ERR_INVALID_ARG: Create SDM channel failed because of invalid argument
+ *      - ESP_ERR_NO_MEM: Create SDM channel failed because out of memory
+ *      - ESP_ERR_NOT_FOUND: Create SDM channel failed because all channels are used up and no more free one
+ *      - ESP_FAIL: Create SDM channel failed because of other error
+ */
+esp_err_t sdm_new_channel(const sdm_config_t *config, sdm_channel_handle_t *ret_chan);
+
+/**
+ * @brief Delete the Sigma Delta channel
+ *
+ * @param[in] chan SDM channel created by `sdm_new_channel`
+ * @return
+ *      - ESP_OK: Delete the SDM channel successfully
+ *      - ESP_ERR_INVALID_ARG: Delete the SDM channel failed because of invalid argument
+ *      - ESP_ERR_INVALID_STATE: Delete the SDM channel failed because the channel is not in init state
+ *      - ESP_FAIL: Delete the SDM channel failed because of other error
+ */
+esp_err_t sdm_del_channel(sdm_channel_handle_t chan);
+
+/**
+ * @brief Enable the Sigma Delta channel
+ *
+ * @note This function will transit the channel state from init to enable.
+ * @note This function will acquire a PM lock, if a specific source clock (e.g. APB) is selected in the `sdm_config_t`, while `CONFIG_PM_ENABLE` is enabled.
+ *
+ * @param[in] chan SDM channel created by `sdm_new_channel`
+ * @return
+ *      - ESP_OK: Enable SDM channel successfully
+ *      - ESP_ERR_INVALID_ARG: Enable SDM channel failed because of invalid argument
+ *      - ESP_ERR_INVALID_STATE: Enable SDM channel failed because the channel is already enabled
+ *      - ESP_FAIL: Enable SDM channel failed because of other error
+ */
+esp_err_t sdm_channel_enable(sdm_channel_handle_t chan);
+
+/**
+ * @brief Disable the Sigma Delta channel
+ *
+ * @note This function will do the opposite work to the `sdm_channel_enable()`
+ *
+ * @param[in] chan SDM channel created by `sdm_new_channel`
+ * @return
+ *      - ESP_OK: Disable SDM channel successfully
+ *      - ESP_ERR_INVALID_ARG: Disable SDM channel failed because of invalid argument
+ *      - ESP_ERR_INVALID_STATE: Disable SDM channel failed because the channel is not enabled yet
+ *      - ESP_FAIL: Disable SDM channel failed because of other error
+ */
+esp_err_t sdm_channel_disable(sdm_channel_handle_t chan);
+
+/**
+ * @brief Set the duty cycle of the PDM output signal.
+ *
+ * @note For PDM signals, duty cycle refers to the percentage of high level cycles to the whole statistical period.
+ *       The average output voltage could be Vout = VDD_IO / 256 * duty + VDD_IO / 2
+ * @note If the duty is set to zero, the output signal is like a 50% duty cycle square wave, with a frequency around (sample_rate_hz / 4).
+ * @note The duty is proportional to the equivalent output voltage after a low-pass-filter.
+ * @note This function is allowed to run within ISR context
+ * @note This function will be placed into IRAM if `CONFIG_SDM_CTRL_FUNC_IN_IRAM` is on, so that it's allowed to be executed when Cache is disabled
+ *
+ * @param[in] chan SDM channel created by `sdm_new_channel`
+ * @param[in] duty Equivalent duty cycle of the PDM output signal, ranges from -128 to 127. But the range of [-90, 90] can provide a better randomness.
+ * @return
+ *      - ESP_OK: Set duty cycle successfully
+ *      - ESP_ERR_INVALID_ARG: Set duty cycle failed because of invalid argument
+ *      - ESP_FAIL: Set duty cycle failed because of other error
+ */
+esp_err_t sdm_channel_set_duty(sdm_channel_handle_t chan, int8_t duty);
+
+#ifdef __cplusplus
+}
+#endif