Merge pull request #23 from lucianomartin/feature/support_rpi4

Support for Buster Raspian on RPi3 and RPi4

CHANGELOG.md

@@ -1,5 +1,13 @@
 # VocalFusion Raspberry Pi Setup Change Log
 
+## 3.0.0
+
+  * Update clock dividers for RPi3 to generate a 12.288MHz clock, since the RPi4 clock at 24.576MHz has glitches
+  * Add support for RPi4 on I2S loader kernel module
+  * Add delay in loading I2S drivers needed for Buster on RPi3
+  * Add script compute_clock_dividers.py to compute dividers for MCLK and BCLK
+  * Fix some indentations and general tidy up
+
 ## 2.3.0
 
   * Add support for 16kHz BCLK generation

loader/i2s_master/Makefile

@@ -1,6 +1,14 @@
-obj-m := loader.o
+obj-m := i2s_master_loader.o
 KDIR := /lib/modules/$(shell uname -r)/build
 PWD := $(shell pwd)
 
-i2s_master: $(PWD)/loader.c 
-	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
+all:
+	# copy the source file to avoid maintaining multiple copies inside the Makefile folders
+	# We tried to use KBUILD_OUTPUT but the module was not compiling
+	cp ../src/loader.c i2s_master_loader.c
+	$(MAKE) -C $(KDIR) M=$(PWD) modules
+	rm i2s_master_loader.c
+
+clean:
+	$(MAKE) -C $(KDIR) M=$(PWD) clean
+

loader/i2s_slave/Makefile

@@ -1,6 +1,14 @@
-obj-m := loader.o
+obj-m := i2s_slave_loader.o
 KDIR := /lib/modules/$(shell uname -r)/build
 PWD := $(shell pwd)
 
-i2s_slave: $(PWD)/loader.c 
-	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
+all:
+	# copy the source file to avoid maintaining multiple copies inside the Makefile folders
+	# We tried to use KBUILD_OUTPUT but the module was not compiling
+	cp ../src/loader.c i2s_slave_loader.c
+	$(MAKE) -C $(KDIR) M=$(PWD) modules
+	rm i2s_slave_loader.c
+
+clean:
+	$(MAKE) -C $(KDIR) M=$(PWD) clean
+

loader/i2s_master/loader.c → loader/src/loader.c

@@ -21,14 +21,26 @@ N.B. playback vs capture is determined by the codec choice
 
 void device_release_callback(struct device *dev) { /* do nothing */ };
 
+#ifdef RPI_4B
+    #define CARD_PLATFORM_STR   "fe203000.i2s"
+#else
+    #define CARD_PLATFORM_STR   "3f203000.i2s"
+#endif
+
+#ifdef I2S_MASTER
+    #define SND_SOC_DAIFMT_CBS_FLAG SND_SOC_DAIFMT_CBS_CFS
+#else
+    #define SND_SOC_DAIFMT_CBS_FLAG SND_SOC_DAIFMT_CBM_CFM
+#endif
+
 static struct asoc_simple_card_info snd_rpi_simple_card_info = {
     .card = "snd_rpi_simple_card", // -> snd_soc_card.name
     .name = "simple-card_codec_link", // -> snd_soc_dai_link.name
     .codec = "snd-soc-dummy", // -> snd_soc_dai_link.codec_name
-    .platform = "3f203000.i2s",
-    .daifmt = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF | SND_SOC_DAIFMT_CBS_CFS,
+    .platform = CARD_PLATFORM_STR,
+    .daifmt = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF | SND_SOC_DAIFMT_CBS_FLAG,
     .cpu_dai = {
-        .name = "3f203000.i2s", // -> snd_soc_dai_link.cpu_dai_name
+        .name = CARD_PLATFORM_STR, // -> snd_soc_dai_link.cpu_dai_name
         .sysclk = 0
     },
     .codec_dai = {
@@ -47,7 +59,7 @@ static struct platform_device snd_rpi_simple_card_device = {
     }
 };
 
-int hello_init(void)
+int snd_rpi_simple_card_init(void)
 {
     const char *dmaengine = "bcm2708-dmaengine"; //module name
     int ret;
@@ -56,19 +68,17 @@ int hello_init(void)
     pr_alert("request module load '%s': %d\n",dmaengine, ret);
     ret = platform_device_register(&snd_rpi_simple_card_device);
     pr_alert("register platform device '%s': %d\n",snd_rpi_simple_card_device.name, ret);
-    pr_alert("Hello World :)\n");
     return 0;
 }
 
-void hello_exit(void)
+void snd_rpi_simple_card_exit(void)
 {
-    // you'll have to sudo modprobe -r the card & codec drivers manually (first?)
     platform_device_unregister(&snd_rpi_simple_card_device);
-    pr_alert("Goodbye World!\n");
+    pr_alert("unregister platform device '%s'\n",snd_rpi_simple_card_device.name);
 }
 
-module_init(hello_init);
-module_exit(hello_exit);
+module_init(snd_rpi_simple_card_init);
+module_exit(snd_rpi_simple_card_exit);
 MODULE_DESCRIPTION("ASoC simple-card I2S setup");
 MODULE_AUTHOR("Plugh Plover");
 MODULE_LICENSE("GPL v2");

resources/clk_dac_setup/compute_clock_dividers.py

@@ -0,0 +1,47 @@
+import argparse
+
+def compute_dividers(source_clock_khz, output_clock_khz):
+    div_i = int(source_clock_khz / output_clock_khz)
+    div_f = int(((source_clock_khz / output_clock_khz) - div_i) * 4096)
+
+    final_output_clock_khz = float(source_clock_khz)*1000/(div_i + div_f/4096)/1000
+
+    return [final_output_clock_khz, div_i, div_f]
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('source_clock_khz', type=int,
+                        help="Source clock frequency in kHz")
+
+    parser.add_argument('desired_mclock_khz', type=int,
+                        help="Desired frequency of MCLK in kHz")
+
+    parser.add_argument('--mclk_pdm_clk_divider', '-d', type=int, default=1, choices=[1, 2],
+                        help="XCore divider from input master clock to 6.144MHz DDR PDM microphone clock")
+
+    args = parser.parse_args()
+
+    [mclk_khz, mclk_div_i, mclk_div_f] = compute_dividers(args.source_clock_khz, args.desired_mclock_khz)
+
+    mclk_bclk_ratio = 4 * args.mclk_pdm_clk_divider
+
+    # The MCLK must be an exact multiple of the BCLK to avoid glitches in the I2S audio
+    desired_bclk_48khz = float(mclk_khz) / mclk_bclk_ratio
+    [bclk_48khz, bclk_48khz_div_i, bclk_48khz_div_f] = compute_dividers(args.source_clock_khz, desired_bclk_48khz)
+
+    desired_bclk_16khz = mclk_khz / (mclk_bclk_ratio * 3)
+    [bclk_16khz, bclk_16khz_div_i, bclk_16khz_div_f] = compute_dividers(args.source_clock_khz, desired_bclk_16khz)
+
+
+    print(f"Given source clock: {args.source_clock_khz}kHz the dividers are:")
+    print(f"\tMCLK: freq {mclk_khz}kHz CLK_I {mclk_div_i} CLK_F {mclk_div_f}")
+    print(f"\tBCLK at 48kHz: freq {bclk_48khz}kHz, ratio {mclk_khz/bclk_48khz}, CLK_I {bclk_48khz_div_i}, CLK_F {bclk_48khz_div_f}")
+    print(f"\tBCLK at 16kHz: freq {bclk_16khz}kHz, ratio {mclk_khz/bclk_16khz}, CLK_I {bclk_16khz_div_i} CLK_F {bclk_16khz_div_f}")
+    if int(args.desired_mclock_khz) != mclk_khz:
+        print(f"Warning: perfect value for MCLK couldn't be found: expected {args.desired_mclock_khz}, found  {mclk_khz}\n")
+    if desired_bclk_48khz != bclk_48khz:
+        print(f"Warning: perfect value for BCLK at 48kHz couldn't be found: expected {desired_bclk_48khz}, found  {bclk_48khz}\n")
+    if desired_bclk_16khz != bclk_16khz:
+        print(f"Warning: perfect value for BCLK at 16kHz couldn't be found: expected {desired_bclk_16khz}, found  {bclk_16khz}")
+
+