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snd-i2s_rpi.c
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snd-i2s_rpi.c
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/*
* =====================================================================================
*
* Filename: snd-i2s_rpi
*
* Description:
*
* Version: 0.0.4
* Created: 2024-01-09
* Revision: none
* Compiler: gcc
*
* Author: Jonas Höchst ([email protected]), originally written by Paul Creaser
* Organization: tRackIT Systems (http://trackit.systems)
*
* =====================================================================================
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/platform_device.h>
#include <sound/simple_card.h>
#include <linux/delay.h>
#include "snd-i2s_rpi.h"
/*
* modified for linux 4.1.5
* inspired by https://github.com/msperl/spi-config
* with thanks for https://github.com/notro/rpi-source/wiki
* as well as Florian Meier for the rpi i2s and dma drivers
*
* to use a differant (simple-card compatible) codec
* change the codec name string in two places and the
* codec_dai name string. (see codec's source file)
*
*
* N.B. playback vs capture is determined by the codec choice
* */
void device_release_callback(struct device *dev) { /* do nothing */ };
static short rpi_platform_generation = 1;
module_param(rpi_platform_generation, short, 0);
MODULE_PARM_DESC(rpi_platform_generation, "Raspberry Pi Generation: 0 = RPiZero; 1 = RPi2, RPi3; 2 = RPi4");
static struct asoc_simple_card_info default_snd_rpi_simple_card_info = {
.card = "snd_rpi_i2s_card", // -> snd_soc_card.name
.name = "simple-card_codec_link", // -> snd_soc_dai_link.name
.codec = "snd-soc-dummy", // "dmic-codec", // -> snd_soc_dai_link.codec_name
.platform = "not-set.i2s",
.daifmt = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF | SND_SOC_DAIFMT_CBS_CFS,
.cpu_dai = {
.name = "not-set.i2s", // -> snd_soc_dai_link.cpu_dai_name
.sysclk = 0
},
.codec_dai = {
.name = "snd-soc-dummy-dai", //"dmic-codec", // -> snd_soc_dai_link.codec_dai_name
.sysclk = 0
},
};
static struct platform_device default_snd_rpi_simple_card_device = {
.name = "asoc-simple-card", //module alias
.id = 0,
.num_resources = 0,
.dev = {
.release = &device_release_callback,
.platform_data = &default_snd_rpi_simple_card_info, // *HACK ALERT*
},
};
static char *pri_platform = "3f203000.i2s";
static char *alt_platform = "20203000.i2s";
static char *pi4_platform = "7e203000.i2s";
static struct asoc_simple_card_info card_info;
static struct platform_device card_device;
int i2s_rpi_init(void)
{
const char *dmaengine = "bcm2708-dmaengine"; //module name
static char *card_platform;
int ret;
printk(KERN_INFO "snd-i2s_rpi: Version %s\n", SND_I2S_RPI_VERSION);
card_platform = pri_platform;
if (rpi_platform_generation == 0) {
card_platform = alt_platform;
} else if (rpi_platform_generation == 2) {
card_platform = pi4_platform;
}
printk(KERN_INFO "snd-i2s_rpi: Setting platform to %s\n", card_platform);
ret = request_module(dmaengine);
// pr_alert("request module load '%s': %d\n",dmaengine, ret);
card_info = default_snd_rpi_simple_card_info;
card_info.platform = card_platform;
card_info.cpu_dai.name = card_platform;
card_device = default_snd_rpi_simple_card_device;
card_device.dev.platform_data = &card_info;
ret = platform_device_register(&card_device);
//pr_alert("register platform device '%s': %d\n",snd_rpi_simple_card_device.name, ret);
return 0;
}
void i2s_rpi_exit(void)
{
// you'll have to sudo modprobe -r the card & codec drivers manually (first?)
platform_device_unregister(&card_device);
//pr_alert("i2s mic module unloaded\n");
}
module_init(i2s_rpi_init);
module_exit(i2s_rpi_exit);
MODULE_DESCRIPTION("ASoC simple-card I2S Microphone");
MODULE_AUTHOR("Jonas Höchst <[email protected]>");
MODULE_LICENSE("GPL v2");