rockchip: Add an I2S driver

Add a driver for I2S which allows audio data to be sent from the SoC to
the audio codec. The sample rate and other settings are hard-coded for now
as there is no suitable device-tree binding available.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

drivers/sound/Kconfig

@@ -21,6 +21,15 @@ config I2S
 	  I2S. It calls either of the two supported codecs (no use is made
 	  of driver model at present).
 
+config I2S_ROCKCHIP
+	bool "Enable I2S support for Rockchip SoCs"
+	depends on I2S
+	help
+	  Rockchip SoCs support an I2S interface for sending audio data to an
+	  audio codec. This option enables support for this, using one of the
+	  available audio codec drivers. This driver does not make use of
+	  DMA, but writes each word directly to the hardware.
+
 config I2S_SAMSUNG
 	bool "Enable I2C support for Samsung SoCs"
 	depends on SOUND

drivers/sound/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_SOUND)	+= i2s-uclass.o
 obj-$(CONFIG_SOUND)	+= sound-uclass.o
 obj-$(CONFIG_I2S_SAMSUNG)	+= samsung-i2s.o
 obj-$(CONFIG_SOUND_SANDBOX)	+= sandbox.o
+obj-$(CONFIG_I2S_ROCKCHIP)	+= rockchip_i2s.o
 obj-$(CONFIG_I2S_SAMSUNG)	+= samsung_sound.o
 obj-$(CONFIG_SOUND_WM8994)	+= wm8994.o
 obj-$(CONFIG_SOUND_MAX98090)	+= max98090.o maxim_codec.o

drivers/sound/rockchip_i2s.c

@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 Google LLC
+ * Copyright 2014 Rockchip Electronics Co., Ltd.
+ * Taken from dc i2s/rockchip.c
+ */
+
+#define LOG_CATEGORY UCLASS_I2S
+
+#include <common.h>
+#include <dm.h>
+#include <i2s.h>
+#include <sound.h>
+#include <asm/io.h>
+
+struct rk_i2s_regs {
+	u32 txcr;		/* I2S_TXCR, 0x00 */
+	u32 rxcr;		/* I2S_RXCR, 0x04 */
+	u32 ckr;		/* I2S_CKR, 0x08 */
+	u32 fifolr;		/* I2S_FIFOLR, 0x0C */
+	u32 dmacr;		/* I2S_DMACR, 0x10 */
+	u32 intcr;		/* I2S_INTCR, 0x14 */
+	u32 intsr;		/* I2S_INTSR, 0x18 */
+	u32 xfer;		/* I2S_XFER, 0x1C */
+	u32 clr;		/* I2S_CLR, 0x20 */
+	u32 txdr;		/* I2S_TXDR, 0x24 */
+	u32 rxdr;		/* I2S_RXDR, 0x28 */
+};
+
+enum {
+	/* I2S_XFER */
+	I2S_RX_TRAN_BIT		= BIT(1),
+	I2S_TX_TRAN_BIT		= BIT(0),
+	I2S_TRAN_MASK		= 3 << 0,
+
+	/* I2S_TXCKR */
+	I2S_MCLK_DIV_SHIFT	= 16,
+	I2S_MCLK_DIV_MASK	= (0xff << I2S_MCLK_DIV_SHIFT),
+
+	I2S_RX_SCLK_DIV_SHIFT	= 8,
+	I2S_RX_SCLK_DIV_MASK	= 0xff << I2S_RX_SCLK_DIV_SHIFT,
+	I2S_TX_SCLK_DIV_SHIFT	= 0,
+	I2S_TX_SCLK_DIV_MASK	= 0xff << I2S_TX_SCLK_DIV_SHIFT,
+
+	I2S_DATA_WIDTH_SHIFT	= 0,
+	I2S_DATA_WIDTH_MASK	= 0x1f << I2S_DATA_WIDTH_SHIFT,
+};
+
+static int rockchip_i2s_init(struct i2s_uc_priv *priv)
+{
+	struct rk_i2s_regs *regs = (struct rk_i2s_regs *)priv->base_address;
+	u32 bps = priv->bitspersample;
+	u32 lrf = priv->rfs;
+	u32 chn = priv->channels;
+	u32 mode = 0;
+
+	clrbits_le32(&regs->xfer, I2S_TX_TRAN_BIT);
+	mode = readl(&regs->txcr) & ~0x1f;
+	switch (priv->bitspersample) {
+	case 16:
+	case 24:
+		mode |= (priv->bitspersample - 1) << I2S_DATA_WIDTH_SHIFT;
+		break;
+	default:
+		log_err("Invalid sample size input %d\n", priv->bitspersample);
+		return -EINVAL;
+	}
+	writel(mode, &regs->txcr);
+
+	mode = readl(&regs->ckr) & ~I2S_MCLK_DIV_MASK;
+	mode |= (lrf / (bps * chn) - 1) << I2S_MCLK_DIV_SHIFT;
+
+	mode &= ~I2S_TX_SCLK_DIV_MASK;
+	mode |= (priv->bitspersample * priv->channels - 1) <<
+			 I2S_TX_SCLK_DIV_SHIFT;
+	writel(mode, &regs->ckr);
+
+	return 0;
+}
+
+static int i2s_send_data(struct rk_i2s_regs *regs, u32 *data, uint length)
+{
+	for (int i = 0; i < min(32u, length); i++)
+		writel(*data++, &regs->txdr);
+
+	length -= min(32u, length);
+
+	/* enable both tx and rx */
+	setbits_le32(&regs->xfer, I2S_TRAN_MASK);
+	while (length) {
+		if ((readl(&regs->fifolr) & 0x3f) < 0x20) {
+			writel(*data++, &regs->txdr);
+			length--;
+		}
+	}
+	while (readl(&regs->fifolr) & 0x3f)
+		/* wait until FIFO empty */;
+	clrbits_le32(&regs->xfer, I2S_TRAN_MASK);
+	writel(0, &regs->clr);
+
+	return 0;
+}
+
+static int rockchip_i2s_tx_data(struct udevice *dev, void *data, uint data_size)
+{
+	struct i2s_uc_priv *priv = dev_get_uclass_priv(dev);
+	struct rk_i2s_regs *regs = (struct rk_i2s_regs *)priv->base_address;
+
+	return i2s_send_data(regs, data, data_size / sizeof(u32));
+}
+
+static int rockchip_i2s_probe(struct udevice *dev)
+{
+	struct i2s_uc_priv *priv = dev_get_uclass_priv(dev);
+	ulong base;
+
+	base = dev_read_addr(dev);
+	if (base == FDT_ADDR_T_NONE) {
+		log_debug("Missing i2s base\n");
+		return -EINVAL;
+	}
+	priv->base_address = base;
+	priv->id = 1;
+	priv->audio_pll_clk = 4800000;
+	priv->samplingrate = 48000;
+	priv->bitspersample = 16;
+	priv->channels = 2;
+	priv->rfs = 256;
+	priv->bfs = 32;
+
+	return rockchip_i2s_init(priv);
+}
+
+static const struct i2s_ops rockchip_i2s_ops = {
+	.tx_data	= rockchip_i2s_tx_data,
+};
+
+static const struct udevice_id rockchip_i2s_ids[] = {
+	{ .compatible = "rockchip,rk3288-i2s" },
+	{ }
+};
+
+U_BOOT_DRIVER(rockchip_i2s) = {
+	.name		= "rockchip_i2s",
+	.id		= UCLASS_I2S,
+	.of_match	= rockchip_i2s_ids,
+	.probe		= rockchip_i2s_probe,
+	.ops		= &rockchip_i2s_ops,
+};