aspeed: Add I2C Driver

Add Device Model based I2C driver for ast2500/ast2400 SoCs.
The driver is very limited, it only supports master mode and
synchronous byte-by-byte reads/writes, no DMA or Pool Buffers.

Signed-off-by: Maxim Sloyko <maxims@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

1 files changed, 357 insertions, 0 deletions

diff --git a/drivers/i2c/ast_i2c.c b/drivers/i2c/ast_i2c.c
new file mode 100644
index 0000000000..16dfb57066
--- /dev/null
+++ b/drivers/i2c/ast_i2c.c
@@ -0,0 +1,357 @@
+/*
+ * Copyright (C) 2012-2020  ASPEED Technology Inc.
+ * Copyright 2016 IBM Corporation
+ * Copyright 2017 Google, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <asm/io.h>
+#include <asm/arch/scu_ast2500.h>
+
+#include "ast_i2c.h"
+
+#define I2C_TIMEOUT_US 100000
+#define I2C_SLEEP_STEP_US 20
+
+#define HIGHSPEED_TTIMEOUT		3
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * Device private data
+ */
+struct ast_i2c_priv {
+	/* This device's clock */
+	struct clk clk;
+	/* Device registers */
+	struct ast_i2c_regs *regs;
+	/* I2C speed in Hz */
+	int speed;
+};
+
+/*
+ * Given desired divider ratio, return the value that needs to be set
+ * in Clock and AC Timing Control register
+ */
+static u32 get_clk_reg_val(ulong divider_ratio)
+{
+	ulong inc = 0, div;
+	ulong scl_low, scl_high, data;
+
+	for (div = 0; divider_ratio >= 16; div++) {
+		inc |= (divider_ratio & 1);
+		divider_ratio >>= 1;
+	}
+	divider_ratio += inc;
+	scl_low = (divider_ratio >> 1) - 1;
+	scl_high = divider_ratio - scl_low - 2;
+	data = I2CD_CACTC_BASE
+			| (scl_high << I2CD_TCKHIGH_SHIFT)
+			| (scl_low << I2CD_TCKLOW_SHIFT)
+			| (div << I2CD_BASE_DIV_SHIFT);
+
+	return data;
+}
+
+static void ast_i2c_clear_interrupts(struct udevice *dev)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+
+	writel(~0, &priv->regs->isr);
+}
+
+static void ast_i2c_init_bus(struct udevice *dev)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+
+	/* Reset device */
+	writel(0, &priv->regs->fcr);
+	/* Enable Master Mode. Assuming single-master */
+	writel(I2CD_MASTER_EN
+	       | I2CD_M_SDA_LOCK_EN
+	       | I2CD_MULTI_MASTER_DIS | I2CD_M_SCL_DRIVE_EN,
+	       &priv->regs->fcr);
+	/* Enable Interrupts */
+	writel(I2CD_INTR_TX_ACK
+	       | I2CD_INTR_TX_NAK
+	       | I2CD_INTR_RX_DONE
+	       | I2CD_INTR_BUS_RECOVER_DONE
+	       | I2CD_INTR_NORMAL_STOP
+	       | I2CD_INTR_ABNORMAL, &priv->regs->icr);
+}
+
+static int ast_i2c_ofdata_to_platdata(struct udevice *dev)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	priv->regs = dev_get_addr_ptr(dev);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	ret = clk_get_by_index(dev, 0, &priv->clk);
+	if (ret < 0) {
+		debug("%s: Can't get clock for %s: %d\n", __func__, dev->name,
+		      ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ast_i2c_probe(struct udevice *dev)
+{
+	struct ast2500_scu *scu;
+
+	debug("Enabling I2C%u\n", dev->seq);
+
+	/*
+	 * Get all I2C devices out of Reset.
+	 * Only needs to be done once, but doing it for every
+	 * device does not hurt.
+	 */
+	scu = ast_get_scu();
+	ast_scu_unlock(scu);
+	clrbits_le32(&scu->sysreset_ctrl1, SCU_SYSRESET_I2C);
+	ast_scu_lock(scu);
+
+	ast_i2c_init_bus(dev);
+
+	return 0;
+}
+
+static int ast_i2c_wait_isr(struct udevice *dev, u32 flag)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	int timeout = I2C_TIMEOUT_US;
+
+	while (!(readl(&priv->regs->isr) & flag) && timeout > 0) {
+		udelay(I2C_SLEEP_STEP_US);
+		timeout -= I2C_SLEEP_STEP_US;
+	}
+
+	ast_i2c_clear_interrupts(dev);
+	if (timeout <= 0)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int ast_i2c_send_stop(struct udevice *dev)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+
+	writel(I2CD_M_STOP_CMD, &priv->regs->csr);
+
+	return ast_i2c_wait_isr(dev, I2CD_INTR_NORMAL_STOP);
+}
+
+static int ast_i2c_wait_tx(struct udevice *dev)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	int timeout = I2C_TIMEOUT_US;
+	u32 flag = I2CD_INTR_TX_ACK | I2CD_INTR_TX_NAK;
+	u32 status = readl(&priv->regs->isr) & flag;
+	int ret = 0;
+
+	while (!status && timeout > 0) {
+		status = readl(&priv->regs->isr) & flag;
+		udelay(I2C_SLEEP_STEP_US);
+		timeout -= I2C_SLEEP_STEP_US;
+	}
+
+	if (status == I2CD_INTR_TX_NAK)
+		ret = -EREMOTEIO;
+
+	if (timeout <= 0)
+		ret = -ETIMEDOUT;
+
+	ast_i2c_clear_interrupts(dev);
+
+	return ret;
+}
+
+static int ast_i2c_start_txn(struct udevice *dev, uint devaddr)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+
+	/* Start and Send Device Address */
+	writel(devaddr, &priv->regs->trbbr);
+	writel(I2CD_M_START_CMD | I2CD_M_TX_CMD, &priv->regs->csr);
+
+	return ast_i2c_wait_tx(dev);
+}
+
+static int ast_i2c_read_data(struct udevice *dev, u8 chip_addr, u8 *buffer,
+			     size_t len, bool send_stop)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	u32 i2c_cmd = I2CD_M_RX_CMD;
+	int ret;
+
+	ret = ast_i2c_start_txn(dev, (chip_addr << 1) | I2C_M_RD);
+	if (ret < 0)
+		return ret;
+
+	for (; len > 0; len--, buffer++) {
+		if (len == 1)
+			i2c_cmd |= I2CD_M_S_RX_CMD_LAST;
+		writel(i2c_cmd, &priv->regs->csr);
+		ret = ast_i2c_wait_isr(dev, I2CD_INTR_RX_DONE);
+		if (ret < 0)
+			return ret;
+		*buffer = (readl(&priv->regs->trbbr) & I2CD_RX_DATA_MASK)
+				>> I2CD_RX_DATA_SHIFT;
+	}
+	ast_i2c_clear_interrupts(dev);
+
+	if (send_stop)
+		return ast_i2c_send_stop(dev);
+
+	return 0;
+}
+
+static int ast_i2c_write_data(struct udevice *dev, u8 chip_addr, u8
+			      *buffer, size_t len, bool send_stop)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = ast_i2c_start_txn(dev, (chip_addr << 1));
+	if (ret < 0)
+		return ret;
+
+	for (; len > 0; len--, buffer++) {
+		writel(*buffer, &priv->regs->trbbr);
+		writel(I2CD_M_TX_CMD, &priv->regs->csr);
+		ret = ast_i2c_wait_tx(dev);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (send_stop)
+		return ast_i2c_send_stop(dev);
+
+	return 0;
+}
+
+static int ast_i2c_deblock(struct udevice *dev)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	struct ast_i2c_regs *regs = priv->regs;
+	u32 csr = readl(&regs->csr);
+	bool sda_high = csr & I2CD_SDA_LINE_STS;
+	bool scl_high = csr & I2CD_SCL_LINE_STS;
+	int ret = 0;
+
+	if (sda_high && scl_high) {
+		/* Bus is idle, no deblocking needed. */
+		return 0;
+	} else if (sda_high) {
+		/* Send stop command */
+		debug("Unterminated TXN in (%x), sending stop\n", csr);
+		ret = ast_i2c_send_stop(dev);
+	} else if (scl_high) {
+		/* Possibly stuck slave */
+		debug("Bus stuck (%x), attempting recovery\n", csr);
+		writel(I2CD_BUS_RECOVER_CMD, &regs->csr);
+		ret = ast_i2c_wait_isr(dev, I2CD_INTR_BUS_RECOVER_DONE);
+	} else {
+		/* Just try to reinit the device. */
+		ast_i2c_init_bus(dev);
+	}
+
+	return ret;
+}
+
+static int ast_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
+{
+	int ret;
+
+	ret = ast_i2c_deblock(dev);
+	if (ret < 0)
+		return ret;
+
+	debug("i2c_xfer: %d messages\n", nmsgs);
+	for (; nmsgs > 0; nmsgs--, msg++) {
+		if (msg->flags & I2C_M_RD) {
+			debug("i2c_read: chip=0x%x, len=0x%x, flags=0x%x\n",
+			      msg->addr, msg->len, msg->flags);
+			ret = ast_i2c_read_data(dev, msg->addr, msg->buf,
+						msg->len, (nmsgs == 1));
+		} else {
+			debug("i2c_write: chip=0x%x, len=0x%x, flags=0x%x\n",
+			      msg->addr, msg->len, msg->flags);
+			ret = ast_i2c_write_data(dev, msg->addr, msg->buf,
+						 msg->len, (nmsgs == 1));
+		}
+		if (ret) {
+			debug("%s: error (%d)\n", __func__, ret);
+			return -EREMOTEIO;
+		}
+	}
+
+	return 0;
+}
+
+static int ast_i2c_set_speed(struct udevice *dev, unsigned int speed)
+{
+	struct ast_i2c_priv *priv = dev_get_priv(dev);
+	struct ast_i2c_regs *regs = priv->regs;
+	ulong i2c_rate, divider;
+
+	debug("Setting speed for I2C%d to <%u>\n", dev->seq, speed);
+	if (!speed) {
+		debug("No valid speed specified\n");
+		return -EINVAL;
+	}
+
+	i2c_rate = clk_get_rate(&priv->clk);
+	divider = i2c_rate / speed;
+
+	priv->speed = speed;
+	if (speed > I2C_HIGHSPEED_RATE) {
+		debug("Enable High Speed\n");
+		setbits_le32(&regs->fcr, I2CD_M_HIGH_SPEED_EN
+			     | I2CD_M_SDA_DRIVE_1T_EN
+			     | I2CD_SDA_DRIVE_1T_EN);
+		writel(HIGHSPEED_TTIMEOUT, &regs->cactcr2);
+	} else {
+		debug("Enabling Normal Speed\n");
+		writel(I2CD_NO_TIMEOUT_CTRL, &regs->cactcr2);
+	}
+
+	writel(get_clk_reg_val(divider), &regs->cactcr1);
+	ast_i2c_clear_interrupts(dev);
+
+	return 0;
+}
+
+static const struct dm_i2c_ops ast_i2c_ops = {
+	.xfer = ast_i2c_xfer,
+	.set_bus_speed = ast_i2c_set_speed,
+	.deblock = ast_i2c_deblock,
+};
+
+static const struct udevice_id ast_i2c_ids[] = {
+	{ .compatible = "aspeed,ast2400-i2c-bus" },
+	{ .compatible = "aspeed,ast2500-i2c-bus" },
+	{ },
+};
+
+U_BOOT_DRIVER(ast_i2c) = {
+	.name = "ast_i2c",
+	.id = UCLASS_I2C,
+	.of_match = ast_i2c_ids,
+	.probe = ast_i2c_probe,
+	.ofdata_to_platdata = ast_i2c_ofdata_to_platdata,
+	.priv_auto_alloc_size = sizeof(struct ast_i2c_priv),
+	.ops = &ast_i2c_ops,
+};