mirror of
https://github.com/isometimes/rpi4-osdev
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99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
#include "../include/audio.h"
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#include "../include/fb.h"
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volatile unsigned* clk = (void*)CLOCK_BASE;
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volatile unsigned* pwm = (void*)PWM_BASE;
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volatile unsigned* dma = (void*)DMA_BASE;
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volatile unsigned* dmae = (void*)DMA_ENABLE;
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volatile unsigned* safe = (void*)DMA_ADDRESS;
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struct dma_cb playback_cb;
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void audio_init(void)
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{
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gpio_useAsAlt0(40); // Ensure PWM1 is mapped to GPIO 40/41
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gpio_useAsAlt0(41);
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wait_msec(2);
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// Setup clock
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*(clk + BCM2711_PWMCLK_CNTL) = PM_PASSWORD | (1 << 5); // Stop clock
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wait_msec(2);
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int idiv = 2;
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*(clk + BCM2711_PWMCLK_DIV) = PM_PASSWORD | (idiv<<12);
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*(clk + BCM2711_PWMCLK_CNTL) = PM_PASSWORD | 16 | 1; // Osc + Enable
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wait_msec(2);
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// Setup PWM
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*(pwm + BCM2711_PWM_CONTROL) = 0;
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wait_msec(2);
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*(pwm+BCM2711_PWM0_RANGE) = 0x264; // 44.1khz, Stereo, 8-bit (54Mhz / 44100 / 2)
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*(pwm+BCM2711_PWM1_RANGE) = 0x264;
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*(pwm+BCM2711_PWM_CONTROL) =
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BCM2711_PWM1_USEFIFO |
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BCM2711_PWM1_ENABLE |
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BCM2711_PWM0_USEFIFO |
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BCM2711_PWM0_ENABLE | 1<<6;
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}
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void audio_play_cpu(unsigned char *data, unsigned int size)
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{
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int i=0;
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long status;
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// Write data out to FIFO
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while (i < size) {
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status = *(pwm + BCM2711_PWM_STATUS);
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if (!(status & BCM2711_FULL1)) {
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*(pwm+BCM2711_PWM_FIFO) = *(data + i);
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i++;
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*(pwm+BCM2711_PWM_FIFO) = *(data + i);
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i++;
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}
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if ((status & ERRORMASK)) {
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*(pwm+BCM2711_PWM_STATUS) = ERRORMASK;
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}
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}
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}
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void audio_play_dma(unsigned char *data, unsigned int size)
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{
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// Convert data (we expect 8-bit samples, but need to convert them to 32-bit words)
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for (int i=0;i<size;i++) *(safe+i) = *(data+i);
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wait_msec(2);
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// Set up control block
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playback_cb.ti = DMA_DEST_DREQ + DMA_PERMAP_1 + DMA_SRC_INC;
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playback_cb.source_ad = DMA_ADDRESS;
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playback_cb.dest_ad = PWM_LEGACY_BASE + 0x18; // Points to PWM_FIFO
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playback_cb.txfr_len = size * 4; // They're unsigned ints now, not unsigned chars
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playback_cb.stride = 0x00;
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playback_cb.nextconbk = 0x00; // Don't loop
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playback_cb.null1 = 0x00;
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playback_cb.null2 = 0x00;
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wait_msec(2);
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// Enable DMA
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*(pwm+BCM2711_PWM_DMAC) =
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BCM2711_PWM_ENAB + 0x0707; // Bits 0-7 Threshold For DREQ Signal = 1, Bits 8-15 Threshold For PANIC Signal = 0
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*dmae = DMA_EN1;
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*(dma+DMA_CONBLK_AD) = (long)&playback_cb; // checked and correct
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wait_msec(2);
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*(dma+DMA_CS) = DMA_ACTIVE;
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}
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void audio_wait_dma(void)
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{
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while (*(dma+DMA_CS) & 0x1); // Wait for DMA transfer to finish - we could do anything here instead!
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}
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