Add driver for rpi-proto

Forward port of 3.10.x driver from https://github.com/koalo
We are using a custom board and would like to use rpi 3.18.x
kernel. Patch works fine for our embedded system.

URL to the audio chip:
http://www.mikroe.com/add-on-boards/audio-voice/audio-codec-proto/

Playback tested with devicetree enabled.

Signed-off-by: Waldemar Brodkorb <wbrodkorb@conet.de>

diff --git a/sound/soc/bcm/rpi-proto.c b/sound/soc/bcm/rpi-proto.c
new file mode 100644 (file)
index 0000000..8227456
--- /dev/null
+++ b/sound/soc/bcm/rpi-proto.c
@@ -0,0 +1,145 @@
+/*
+ * ASoC driver for PROTO AudioCODEC (with a WM8731)
+ * connected to a Raspberry Pi
+ *
+ * Author:      Florian Meier, <koalo@koalo.de>
+ *           Copyright 2013
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/soc.h>
+#include <sound/jack.h>
+
+#include "../codecs/wm8731.h"
+
+static const unsigned int wm8731_rates_12288000[] = {
+       8000, 32000, 48000, 96000,
+};
+
+static struct snd_pcm_hw_constraint_list wm8731_constraints_12288000 = {
+       .list = wm8731_rates_12288000,
+       .count = ARRAY_SIZE(wm8731_rates_12288000),
+};
+
+static int snd_rpi_proto_startup(struct snd_pcm_substream *substream)
+{
+       /* Setup constraints, because there is a 12.288 MHz XTAL on the board */
+       snd_pcm_hw_constraint_list(substream->runtime, 0,
+                               SNDRV_PCM_HW_PARAM_RATE,
+                               &wm8731_constraints_12288000);
+       return 0;
+}
+
+static int snd_rpi_proto_hw_params(struct snd_pcm_substream *substream,
+                                      struct snd_pcm_hw_params *params)
+{
+       struct snd_soc_pcm_runtime *rtd = substream->private_data;
+       struct snd_soc_dai *codec_dai = rtd->codec_dai;
+       struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
+       int sysclk = 12288000; /* This is fixed on this board */
+
+       /* Set proto bclk */
+       int ret = snd_soc_dai_set_bclk_ratio(cpu_dai,32*2);
+       if (ret < 0){
+               dev_err(rtd->card->dev,
+                               "Failed to set BCLK ratio %d\n", ret);
+               return ret;
+       }
+
+       /* Set proto sysclk */
+       ret = snd_soc_dai_set_sysclk(codec_dai, WM8731_SYSCLK_XTAL,
+                       sysclk, SND_SOC_CLOCK_IN);
+       if (ret < 0) {
+               dev_err(rtd->card->dev,
+                               "Failed to set WM8731 SYSCLK: %d\n", ret);
+               return ret;
+       }
+
+       return 0;
+}
+
+/* machine stream operations */
+static struct snd_soc_ops snd_rpi_proto_ops = {
+       .startup = snd_rpi_proto_startup,
+       .hw_params = snd_rpi_proto_hw_params,
+};
+
+static struct snd_soc_dai_link snd_rpi_proto_dai[] = {
+{
+       .name           = "WM8731",
+       .stream_name    = "WM8731 HiFi",
+       .cpu_dai_name   = "bcm2708-i2s.0",
+       .codec_dai_name = "wm8731-hifi",
+       .platform_name  = "bcm2708-i2s.0",
+       .codec_name     = "wm8731.1-001a",
+       .dai_fmt        = SND_SOC_DAIFMT_I2S
+                               | SND_SOC_DAIFMT_NB_NF
+                               | SND_SOC_DAIFMT_CBM_CFM,
+       .ops            = &snd_rpi_proto_ops,
+},
+};
+
+/* audio machine driver */
+static struct snd_soc_card snd_rpi_proto = {
+       .name           = "snd_rpi_proto",
+       .owner          = THIS_MODULE,
+       .dai_link       = snd_rpi_proto_dai,
+       .num_links      = ARRAY_SIZE(snd_rpi_proto_dai),
+};
+
+static int snd_rpi_proto_probe(struct platform_device *pdev)
+{
+       int ret = 0;
+
+       snd_rpi_proto.dev = &pdev->dev;
+
+       if (pdev->dev.of_node) {
+               struct device_node *i2s_node;
+               struct snd_soc_dai_link *dai = &snd_rpi_proto_dai[0];
+               i2s_node = of_parse_phandle(pdev->dev.of_node,
+                                           "i2s-controller", 0);
+
+               if (i2s_node) {
+                       dai->cpu_dai_name = NULL;
+                       dai->cpu_of_node = i2s_node;
+                       dai->platform_name = NULL;
+                       dai->platform_of_node = i2s_node;
+               }
+       }
+
+       ret = devm_snd_soc_register_card(&pdev->dev, &snd_rpi_proto);
+       if (ret && ret != -EPROBE_DEFER)
+               dev_err(&pdev->dev,
+                               "snd_soc_register_card() failed: %d\n", ret);
+
+       return ret;
+}
+
+static const struct of_device_id snd_rpi_proto_of_match[] = {
+       { .compatible = "rpi,rpi-proto", },
+       {},
+};
+MODULE_DEVICE_TABLE(of, snd_rpi_proto_of_match);
+
+static struct platform_driver snd_rpi_proto_driver = {
+       .driver = {
+               .name   = "snd-rpi-proto",
+               .owner  = THIS_MODULE,
+               .of_match_table = snd_rpi_proto_of_match,
+       },
+       .probe    = snd_rpi_proto_probe,
+};
+
+module_platform_driver(snd_rpi_proto_driver);
+
+MODULE_AUTHOR("Florian Meier");
+MODULE_DESCRIPTION("ASoC Driver for Raspberry Pi connected to PROTO board (WM8731)");
+MODULE_LICENSE("GPL");