--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include <sound/soc.h>
+
+/*
+ * The I2S interface consists of two ring buffers - one for RX and one for
+ * TX. A ring buffer has a producer index and a consumer index. Depending
+ * on which way the data is flowing, either the software or the hardware
+ * writes data and updates the producer index, and the other end reads data
+ * and updates the consumer index.
+ *
+ * The pointer managed by software is updated using the .ack callback
+ * (see chv3_dma_ack). This seems to be the only way to reliably obtain
+ * the appl_ptr from within the driver and pass it to hardware.
+ *
+ * Because of the two pointer design, the ring buffer can never be full. With
+ * capture this isn't a problem, because the hardware being the producer
+ * will wait for the consumer index to move out of the way. With playback,
+ * however, this is problematic, because ALSA wants to fill up the buffer
+ * completely when waiting for hardware. In the .ack callback, the driver
+ * would have to wait for the consumer index to move out of the way by
+ * busy-waiting, which would keep stalling the kernel for quite a long time.
+ *
+ * The workaround to this problem is to "lie" to ALSA that the hw_pointer
+ * is one frame behind what it actually is (see chv3_dma_pointer). This
+ * way, ALSA will not try to fill up the entire buffer, and all callbacks
+ * are wait-free.
+ */
+
+#define I2S_TX_ENABLE 0x00
+#define I2S_TX_BASE_ADDR 0x04
+#define I2S_TX_BUFFER_SIZE 0x08
+#define I2S_TX_PRODUCER_IDX 0x0c
+#define I2S_TX_CONSUMER_IDX 0x10
+#define I2S_RX_ENABLE 0x14
+#define I2S_RX_BASE_ADDR 0x18
+#define I2S_RX_BUFFER_SIZE 0x1c
+#define I2S_RX_PRODUCER_IDX 0x20
+#define I2S_RX_CONSUMER_IDX 0x24
+
+#define I2S_SOFT_RESET 0x2c
+#define I2S_SOFT_RESET_RX_BIT 0x1
+#define I2S_SOFT_RESET_TX_BIT 0x2
+
+#define I2S_RX_IRQ 0x4c
+#define I2S_RX_IRQ_CONST 0x50
+#define I2S_TX_IRQ 0x54
+#define I2S_TX_IRQ_CONST 0x58
+
+#define I2S_IRQ_MASK 0x8
+#define I2S_IRQ_CLR 0xc
+#define I2S_IRQ_RX_BIT 0x1
+#define I2S_IRQ_TX_BIT 0x2
+
+#define I2S_MAX_BUFFER_SIZE 0x200000
+
+struct chv3_i2s_dev {
+ struct device *dev;
+ void __iomem *iobase;
+ void __iomem *iobase_irq;
+ struct snd_pcm_substream *rx_substream;
+ struct snd_pcm_substream *tx_substream;
+ int tx_bytes_to_fetch;
+};
+
+static struct snd_soc_dai_driver chv3_i2s_dai = {
+ .name = "chv3-i2s",
+ .capture = {
+ .channels_min = 1,
+ .channels_max = 128,
+ .rates = SNDRV_PCM_RATE_CONTINUOUS,
+ .rate_min = 8000,
+ .rate_max = 96000,
+ .formats = SNDRV_PCM_FMTBIT_S32_LE,
+ },
+ .playback = {
+ .channels_min = 1,
+ .channels_max = 128,
+ .rates = SNDRV_PCM_RATE_CONTINUOUS,
+ .rate_min = 8000,
+ .rate_max = 96000,
+ .formats = SNDRV_PCM_FMTBIT_S32_LE,
+ },
+};
+
+static const struct snd_pcm_hardware chv3_dma_hw = {
+ .info = SNDRV_PCM_INFO_INTERLEAVED |
+ SNDRV_PCM_INFO_MMAP |
+ SNDRV_PCM_INFO_MMAP_VALID |
+ SNDRV_PCM_INFO_BLOCK_TRANSFER,
+ .buffer_bytes_max = I2S_MAX_BUFFER_SIZE,
+ .period_bytes_min = 64,
+ .period_bytes_max = 8192,
+ .periods_min = 4,
+ .periods_max = 256,
+};
+
+static inline void chv3_i2s_wr(struct chv3_i2s_dev *i2s, int offset, u32 val)
+{
+ writel(val, i2s->iobase + offset);
+}
+
+static inline u32 chv3_i2s_rd(struct chv3_i2s_dev *i2s, int offset)
+{
+ return readl(i2s->iobase + offset);
+}
+
+static irqreturn_t chv3_i2s_isr(int irq, void *data)
+{
+ struct chv3_i2s_dev *i2s = data;
+ u32 reg;
+
+ reg = readl(i2s->iobase_irq + I2S_IRQ_CLR);
+ if (!reg)
+ return IRQ_NONE;
+
+ if (reg & I2S_IRQ_RX_BIT)
+ snd_pcm_period_elapsed(i2s->rx_substream);
+
+ if (reg & I2S_IRQ_TX_BIT)
+ snd_pcm_period_elapsed(i2s->tx_substream);
+
+ writel(reg, i2s->iobase_irq + I2S_IRQ_CLR);
+
+ return IRQ_HANDLED;
+}
+
+static int chv3_dma_open(struct snd_soc_component *component,
+ struct snd_pcm_substream *substream)
+{
+ struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+ struct chv3_i2s_dev *i2s = snd_soc_dai_get_drvdata(asoc_rtd_to_cpu(rtd, 0));
+ int res;
+
+ snd_soc_set_runtime_hwparams(substream, &chv3_dma_hw);
+
+ res = snd_pcm_hw_constraint_pow2(substream->runtime, 0,
+ SNDRV_PCM_HW_PARAM_BUFFER_BYTES);
+ if (res)
+ return res;
+
+ if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+ i2s->rx_substream = substream;
+ else
+ i2s->tx_substream = substream;
+
+ return 0;
+}
+static int chv3_dma_close(struct snd_soc_component *component,
+ struct snd_pcm_substream *substream)
+{
+ struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+ struct chv3_i2s_dev *i2s = snd_soc_dai_get_drvdata(asoc_rtd_to_cpu(rtd, 0));
+
+ if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
+ chv3_i2s_wr(i2s, I2S_RX_ENABLE, 0);
+ else
+ chv3_i2s_wr(i2s, I2S_TX_ENABLE, 0);
+
+ return 0;
+}
+
+static int chv3_dma_pcm_construct(struct snd_soc_component *component,
+ struct snd_soc_pcm_runtime *rtd)
+{
+ struct chv3_i2s_dev *i2s = snd_soc_dai_get_drvdata(asoc_rtd_to_cpu(rtd, 0));
+ struct snd_pcm_substream *substream;
+ int res;
+
+ substream = rtd->pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream;
+ if (substream) {
+ res = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, i2s->dev,
+ I2S_MAX_BUFFER_SIZE, &substream->dma_buffer);
+ if (res)
+ return res;
+ }
+
+ substream = rtd->pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
+ if (substream) {
+ res = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, i2s->dev,
+ I2S_MAX_BUFFER_SIZE, &substream->dma_buffer);
+ if (res)
+ return res;
+ }
+
+ return 0;
+}
+
+static int chv3_dma_hw_params(struct snd_soc_component *component,
+ struct snd_pcm_substream *substream,
+ struct snd_pcm_hw_params *params)
+{
+ snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
+ return 0;
+}
+
+static int chv3_dma_prepare(struct snd_soc_component *component,
+ struct snd_pcm_substream *substream)
+{
+ struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+ struct chv3_i2s_dev *i2s = snd_soc_dai_get_drvdata(asoc_rtd_to_cpu(rtd, 0));
+ unsigned int buffer_bytes, period_bytes, period_size;
+
+ buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
+ period_bytes = snd_pcm_lib_period_bytes(substream);
+ period_size = substream->runtime->period_size;
+
+ if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE) {
+ chv3_i2s_wr(i2s, I2S_SOFT_RESET, I2S_SOFT_RESET_RX_BIT);
+ chv3_i2s_wr(i2s, I2S_RX_BASE_ADDR, substream->dma_buffer.addr);
+ chv3_i2s_wr(i2s, I2S_RX_BUFFER_SIZE, buffer_bytes);
+ chv3_i2s_wr(i2s, I2S_RX_IRQ, (period_size << 8) | 1);
+ chv3_i2s_wr(i2s, I2S_RX_ENABLE, 1);
+ } else {
+ chv3_i2s_wr(i2s, I2S_SOFT_RESET, I2S_SOFT_RESET_TX_BIT);
+ chv3_i2s_wr(i2s, I2S_TX_BASE_ADDR, substream->dma_buffer.addr);
+ chv3_i2s_wr(i2s, I2S_TX_BUFFER_SIZE, buffer_bytes);
+ chv3_i2s_wr(i2s, I2S_TX_IRQ, ((period_bytes / i2s->tx_bytes_to_fetch) << 8) | 1);
+ chv3_i2s_wr(i2s, I2S_TX_ENABLE, 1);
+ }
+ writel(I2S_IRQ_RX_BIT | I2S_IRQ_TX_BIT, i2s->iobase_irq + I2S_IRQ_MASK);
+
+ return 0;
+}
+
+static snd_pcm_uframes_t chv3_dma_pointer(struct snd_soc_component *component,
+ struct snd_pcm_substream *substream)
+{
+ struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+ struct chv3_i2s_dev *i2s = snd_soc_dai_get_drvdata(asoc_rtd_to_cpu(rtd, 0));
+ u32 frame_bytes, buffer_bytes;
+ u32 idx_bytes;
+
+ frame_bytes = substream->runtime->frame_bits * 8;
+ buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
+
+ if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE) {
+ idx_bytes = chv3_i2s_rd(i2s, I2S_RX_PRODUCER_IDX);
+ } else {
+ idx_bytes = chv3_i2s_rd(i2s, I2S_TX_CONSUMER_IDX);
+ /* lag the pointer by one frame */
+ idx_bytes = (idx_bytes - frame_bytes) & (buffer_bytes - 1);
+ }
+
+ return bytes_to_frames(substream->runtime, idx_bytes);
+}
+
+static int chv3_dma_ack(struct snd_soc_component *component,
+ struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
+ struct chv3_i2s_dev *i2s = snd_soc_dai_get_drvdata(asoc_rtd_to_cpu(rtd, 0));
+ unsigned int bytes, idx;
+
+ bytes = frames_to_bytes(runtime, runtime->control->appl_ptr);
+ idx = bytes & (snd_pcm_lib_buffer_bytes(substream) - 1);
+
+ if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
+ chv3_i2s_wr(i2s, I2S_RX_CONSUMER_IDX, idx);
+ else
+ chv3_i2s_wr(i2s, I2S_TX_PRODUCER_IDX, idx);
+
+ return 0;
+}
+
+static const struct snd_soc_component_driver chv3_i2s_comp = {
+ .name = "chv3-i2s-comp",
+ .open = chv3_dma_open,
+ .close = chv3_dma_close,
+ .pcm_construct = chv3_dma_pcm_construct,
+ .hw_params = chv3_dma_hw_params,
+ .prepare = chv3_dma_prepare,
+ .pointer = chv3_dma_pointer,
+ .ack = chv3_dma_ack,
+};
+
+static int chv3_i2s_probe(struct platform_device *pdev)
+{
+ struct chv3_i2s_dev *i2s;
+ int res;
+ int irq;
+
+ i2s = devm_kzalloc(&pdev->dev, sizeof(*i2s), GFP_KERNEL);
+ if (!i2s)
+ return -ENOMEM;
+
+ i2s->iobase = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(i2s->iobase))
+ return PTR_ERR(i2s->iobase);
+
+ i2s->iobase_irq = devm_platform_ioremap_resource(pdev, 1);
+ if (IS_ERR(i2s->iobase_irq))
+ return PTR_ERR(i2s->iobase_irq);
+
+ i2s->tx_bytes_to_fetch = (chv3_i2s_rd(i2s, I2S_TX_IRQ_CONST) >> 8) & 0xffff;
+
+ i2s->dev = &pdev->dev;
+ dev_set_drvdata(&pdev->dev, i2s);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return -ENXIO;
+ res = devm_request_irq(i2s->dev, irq, chv3_i2s_isr, 0, "chv3-i2s", i2s);
+ if (res)
+ return res;
+
+ res = devm_snd_soc_register_component(&pdev->dev, &chv3_i2s_comp,
+ &chv3_i2s_dai, 1);
+ if (res) {
+ dev_err(&pdev->dev, "couldn't register component: %d\n", res);
+ return res;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id chv3_i2s_of_match[] = {
+ { .compatible = "google,chv3-i2s" },
+ {},
+};
+
+static struct platform_driver chv3_i2s_driver = {
+ .probe = chv3_i2s_probe,
+ .driver = {
+ .name = "chv3-i2s",
+ .of_match_table = chv3_i2s_of_match,
+ },
+};
+
+module_platform_driver(chv3_i2s_driver);
+
+MODULE_AUTHOR("Pawel Anikiel <pan@semihalf.com>");
+MODULE_DESCRIPTION("Chameleon v3 I2S interface");
+MODULE_LICENSE("GPL");
projects / platform / kernel / linux-starfive.git / commitdiff