1 files changed, 439 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-uniphier.c b/drivers/i2c/busses/i2c-uniphier.c
new file mode 100644
index 000000000..e3ebae381
--- /dev/null
+++ b/drivers/i2c/busses/i2c-uniphier.c
@@ -0,0 +1,439 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define UNIPHIER_I2C_DTRM	0x00	/* TX register */
+#define     UNIPHIER_I2C_DTRM_IRQEN	BIT(11)	/* enable interrupt */
+#define     UNIPHIER_I2C_DTRM_STA	BIT(10)	/* start condition */
+#define     UNIPHIER_I2C_DTRM_STO	BIT(9)	/* stop condition */
+#define     UNIPHIER_I2C_DTRM_NACK	BIT(8)	/* do not return ACK */
+#define     UNIPHIER_I2C_DTRM_RD	BIT(0)	/* read transaction */
+#define UNIPHIER_I2C_DREC	0x04	/* RX register */
+#define     UNIPHIER_I2C_DREC_MST	BIT(14)	/* 1 = master, 0 = slave */
+#define     UNIPHIER_I2C_DREC_TX	BIT(13)	/* 1 = transmit, 0 = receive */
+#define     UNIPHIER_I2C_DREC_STS	BIT(12)	/* stop condition detected */
+#define     UNIPHIER_I2C_DREC_LRB	BIT(11)	/* no ACK */
+#define     UNIPHIER_I2C_DREC_LAB	BIT(9)	/* arbitration lost */
+#define     UNIPHIER_I2C_DREC_BBN	BIT(8)	/* bus not busy */
+#define UNIPHIER_I2C_MYAD	0x08	/* slave address */
+#define UNIPHIER_I2C_CLK	0x0c	/* clock frequency control */
+#define UNIPHIER_I2C_BRST	0x10	/* bus reset */
+#define     UNIPHIER_I2C_BRST_FOEN	BIT(1)	/* normal operation */
+#define     UNIPHIER_I2C_BRST_RSCL	BIT(0)	/* release SCL */
+#define UNIPHIER_I2C_HOLD	0x14	/* hold time control */
+#define UNIPHIER_I2C_BSTS	0x18	/* bus status monitor */
+#define     UNIPHIER_I2C_BSTS_SDA	BIT(1)	/* readback of SDA line */
+#define     UNIPHIER_I2C_BSTS_SCL	BIT(0)	/* readback of SCL line */
+#define UNIPHIER_I2C_NOISE	0x1c	/* noise filter control */
+#define UNIPHIER_I2C_SETUP	0x20	/* setup time control */
+
+struct uniphier_i2c_priv {
+	struct completion comp;
+	struct i2c_adapter adap;
+	void __iomem *membase;
+	struct clk *clk;
+	unsigned int busy_cnt;
+	unsigned int clk_cycle;
+};
+
+static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
+{
+	struct uniphier_i2c_priv *priv = dev_id;
+
+	/*
+	 * This hardware uses edge triggered interrupt.  Do not touch the
+	 * hardware registers in this handler to make sure to catch the next
+	 * interrupt edge.  Just send a complete signal and return.
+	 */
+	complete(&priv->comp);
+
+	return IRQ_HANDLED;
+}
+
+static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata,
+				  u32 *rxdatap)
+{
+	struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+	unsigned long time_left;
+	u32 rxdata;
+
+	reinit_completion(&priv->comp);
+
+	txdata |= UNIPHIER_I2C_DTRM_IRQEN;
+	writel(txdata, priv->membase + UNIPHIER_I2C_DTRM);
+
+	time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
+	if (unlikely(!time_left)) {
+		dev_err(&adap->dev, "transaction timeout\n");
+		return -ETIMEDOUT;
+	}
+
+	rxdata = readl(priv->membase + UNIPHIER_I2C_DREC);
+	if (rxdatap)
+		*rxdatap = rxdata;
+
+	return 0;
+}
+
+static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata)
+{
+	u32 rxdata;
+	int ret;
+
+	ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata);
+	if (ret)
+		return ret;
+
+	if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB))
+		return -EAGAIN;
+
+	if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB))
+		return -ENXIO;
+
+	return 0;
+}
+
+static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len,
+			   const u8 *buf)
+{
+	int ret;
+
+	ret = uniphier_i2c_send_byte(adap, addr << 1 |
+				     UNIPHIER_I2C_DTRM_STA |
+				     UNIPHIER_I2C_DTRM_NACK);
+	if (ret)
+		return ret;
+
+	while (len--) {
+		ret = uniphier_i2c_send_byte(adap,
+					     UNIPHIER_I2C_DTRM_NACK | *buf++);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len,
+			   u8 *buf)
+{
+	int ret;
+
+	ret = uniphier_i2c_send_byte(adap, addr << 1 |
+				     UNIPHIER_I2C_DTRM_STA |
+				     UNIPHIER_I2C_DTRM_NACK |
+				     UNIPHIER_I2C_DTRM_RD);
+	if (ret)
+		return ret;
+
+	while (len--) {
+		u32 rxdata;
+
+		ret = uniphier_i2c_xfer_byte(adap,
+					     len ? 0 : UNIPHIER_I2C_DTRM_NACK,
+					     &rxdata);
+		if (ret)
+			return ret;
+		*buf++ = rxdata;
+	}
+
+	return 0;
+}
+
+static int uniphier_i2c_stop(struct i2c_adapter *adap)
+{
+	return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO |
+				      UNIPHIER_I2C_DTRM_NACK);
+}
+
+static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap,
+					struct i2c_msg *msg, bool stop)
+{
+	bool is_read = msg->flags & I2C_M_RD;
+	bool recovery = false;
+	int ret;
+
+	if (is_read)
+		ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf);
+	else
+		ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf);
+
+	if (ret == -EAGAIN) /* could not acquire bus. bail out without STOP */
+		return ret;
+
+	if (ret == -ETIMEDOUT) {
+		/* This error is fatal.  Needs recovery. */
+		stop = false;
+		recovery = true;
+	}
+
+	if (stop) {
+		int ret2 = uniphier_i2c_stop(adap);
+
+		if (ret2) {
+			/* Failed to issue STOP.  The bus needs recovery. */
+			recovery = true;
+			ret = ret ?: ret2;
+		}
+	}
+
+	if (recovery)
+		i2c_recover_bus(adap);
+
+	return ret;
+}
+
+static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap)
+{
+	struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	if (!(readl(priv->membase + UNIPHIER_I2C_DREC) &
+						UNIPHIER_I2C_DREC_BBN)) {
+		if (priv->busy_cnt++ > 3) {
+			/*
+			 * If bus busy continues too long, it is probably
+			 * in a wrong state.  Try bus recovery.
+			 */
+			i2c_recover_bus(adap);
+			priv->busy_cnt = 0;
+		}
+
+		return -EAGAIN;
+	}
+
+	priv->busy_cnt = 0;
+	return 0;
+}
+
+static int uniphier_i2c_master_xfer(struct i2c_adapter *adap,
+				    struct i2c_msg *msgs, int num)
+{
+	struct i2c_msg *msg, *emsg = msgs + num;
+	int ret;
+
+	ret = uniphier_i2c_check_bus_busy(adap);
+	if (ret)
+		return ret;
+
+	for (msg = msgs; msg < emsg; msg++) {
+		/* Emit STOP if it is the last message or I2C_M_STOP is set. */
+		bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP);
+
+		ret = uniphier_i2c_master_xfer_one(adap, msg, stop);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static u32 uniphier_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm uniphier_i2c_algo = {
+	.master_xfer = uniphier_i2c_master_xfer,
+	.functionality = uniphier_i2c_functionality,
+};
+
+static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on)
+{
+	u32 val = UNIPHIER_I2C_BRST_RSCL;
+
+	val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN;
+	writel(val, priv->membase + UNIPHIER_I2C_BRST);
+}
+
+static int uniphier_i2c_get_scl(struct i2c_adapter *adap)
+{
+	struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
+							UNIPHIER_I2C_BSTS_SCL);
+}
+
+static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+	struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	writel(val ? UNIPHIER_I2C_BRST_RSCL : 0,
+	       priv->membase + UNIPHIER_I2C_BRST);
+}
+
+static int uniphier_i2c_get_sda(struct i2c_adapter *adap)
+{
+	struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
+							UNIPHIER_I2C_BSTS_SDA);
+}
+
+static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap)
+{
+	uniphier_i2c_reset(i2c_get_adapdata(adap), false);
+}
+
+static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = {
+	.recover_bus = i2c_generic_scl_recovery,
+	.get_scl = uniphier_i2c_get_scl,
+	.set_scl = uniphier_i2c_set_scl,
+	.get_sda = uniphier_i2c_get_sda,
+	.unprepare_recovery = uniphier_i2c_unprepare_recovery,
+};
+
+static void uniphier_i2c_hw_init(struct uniphier_i2c_priv *priv)
+{
+	unsigned int cyc = priv->clk_cycle;
+
+	uniphier_i2c_reset(priv, true);
+
+	/*
+	 * Bit30-16: clock cycles of tLOW.
+	 *  Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us
+	 *  Fast-mode:     tLOW = 1.3 us, tHIGH = 0.6 us
+	 * "tLow/tHIGH = 5/4" meets both.
+	 */
+	writel((cyc * 5 / 9 << 16) | cyc, priv->membase + UNIPHIER_I2C_CLK);
+
+	uniphier_i2c_reset(priv, false);
+}
+
+static int uniphier_i2c_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_i2c_priv *priv;
+	u32 bus_speed;
+	unsigned long clk_rate;
+	int irq, ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->membase = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->membase))
+		return PTR_ERR(priv->membase);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
+		bus_speed = I2C_MAX_STANDARD_MODE_FREQ;
+
+	if (!bus_speed || bus_speed > I2C_MAX_FAST_MODE_FREQ) {
+		dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
+		return -EINVAL;
+	}
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret)
+		return ret;
+
+	clk_rate = clk_get_rate(priv->clk);
+	if (!clk_rate) {
+		dev_err(dev, "input clock rate should not be zero\n");
+		ret = -EINVAL;
+		goto disable_clk;
+	}
+
+	priv->clk_cycle = clk_rate / bus_speed;
+	init_completion(&priv->comp);
+	priv->adap.owner = THIS_MODULE;
+	priv->adap.algo = &uniphier_i2c_algo;
+	priv->adap.dev.parent = dev;
+	priv->adap.dev.of_node = dev->of_node;
+	strscpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name));
+	priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info;
+	i2c_set_adapdata(&priv->adap, priv);
+	platform_set_drvdata(pdev, priv);
+
+	uniphier_i2c_hw_init(priv);
+
+	ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
+			       priv);
+	if (ret) {
+		dev_err(dev, "failed to request irq %d\n", irq);
+		goto disable_clk;
+	}
+
+	ret = i2c_add_adapter(&priv->adap);
+disable_clk:
+	if (ret)
+		clk_disable_unprepare(priv->clk);
+
+	return ret;
+}
+
+static int uniphier_i2c_remove(struct platform_device *pdev)
+{
+	struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&priv->adap);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused uniphier_i2c_suspend(struct device *dev)
+{
+	struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused uniphier_i2c_resume(struct device *dev)
+{
+	struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret)
+		return ret;
+
+	uniphier_i2c_hw_init(priv);
+
+	return 0;
+}
+
+static const struct dev_pm_ops uniphier_i2c_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(uniphier_i2c_suspend, uniphier_i2c_resume)
+};
+
+static const struct of_device_id uniphier_i2c_match[] = {
+	{ .compatible = "socionext,uniphier-i2c" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_i2c_match);
+
+static struct platform_driver uniphier_i2c_drv = {
+	.probe  = uniphier_i2c_probe,
+	.remove = uniphier_i2c_remove,
+	.driver = {
+		.name  = "uniphier-i2c",
+		.of_match_table = uniphier_i2c_match,
+		.pm = &uniphier_i2c_pm_ops,
+	},
+};
+module_platform_driver(uniphier_i2c_drv);
+
+MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
+MODULE_DESCRIPTION("UniPhier I2C bus driver");
+MODULE_LICENSE("GPL");