i2s_dma: Implementation of I2S + DMA wrapper library

extras/i2s_dma/i2s_dma.h

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+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 sheinz (https://github.com/sheinz)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef __I2S_DMA_H__
+#define __I2S_DMA_H__
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "esp/slc_regs.h"
+
+typedef void (*i2s_dma_isr_t)(void);
+
+typedef struct dma_descriptor {
+    uint32_t blocksize:12;
+    uint32_t datalen:12;
+    uint32_t unused:5;
+    uint32_t sub_sof:1;
+    uint32_t eof:1;
+    uint32_t owner:1;
+
+    void* buf_ptr;
+    struct dma_descriptor *next_link_ptr;
+} dma_descriptor_t;
+
+typedef struct {
+    uint8_t bclk_div;
+    uint8_t clkm_div;
+} i2s_clock_div_t;
+
+typedef struct {
+    bool data;
+    bool clock;
+    bool ws;
+} i2s_pins_t;
+
+/**
+ * Initialize I2S and DMA subsystems.
+ *
+ * @param isr ISR handler. Can be NULL if interrupt handling is not needed.
+ * @param clock_div I2S clock configuration.
+ * @param pins I2S pin configuration. Specifies which pins are enabled in I2S.
+ */
+void i2s_dma_init(i2s_dma_isr_t isr, i2s_clock_div_t clock_div, i2s_pins_t pins);
+
+/**
+ * Calculate I2S dividers for the specified frequency.
+ *
+ * I2S_FREQ = 160000000 / (bclk_div * clkm_div)
+ * Base frequency is independent from the CPU frequency.
+ */
+i2s_clock_div_t i2s_get_clock_div(int32_t freq);
+
+/**
+ * Start I2S transmittion.
+ *
+ * @param descr Pointer to the first descriptor in the linked list of descriptors.
+ */
+void i2s_dma_start(dma_descriptor_t *descr);
+
+/**
+ * Stop I2S transmittion.
+ */
+void i2s_dma_stop();
+
+/**
+ * Clear interrupt in the I2S ISR handler.
+ *
+ * It is intended to be called from ISR.
+ */
+inline void i2s_dma_clear_interrupt()
+{
+    SLC.INT_CLEAR = 0xFFFFFFFF;
+}
+
+/**
+ * Check if it is EOF interrupt.
+ *
+ * It is intended to be called from ISR.
+ */
+inline bool i2s_dma_is_eof_interrupt()
+{
+    return (SLC.INT_STATUS & SLC_INT_STATUS_RX_EOF);
+}
+
+/**
+ * Get pointer to a descriptor that caused EOF interrupt.
+ * It is the last processed descriptor.
+ *
+ * It is intended to be called from ISR.
+ */
+inline dma_descriptor_t *i2s_dma_get_eof_descriptor()
+{
+    return (dma_descriptor_t*)SLC.RX_EOF_DESCRIPTOR_ADDR;
+}
+
+#endif  // __I2S_DMA_H__