1 files changed, 296 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
new file mode 100644
index 000000000..0d15f4c1e
--- /dev/null
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Synopsys DesignWare I2C adapter driver (slave only).
+ *
+ * Based on the Synopsys DesignWare I2C adapter driver (master).
+ *
+ * Copyright (C) 2016 Synopsys Inc.
+ */
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#include "i2c-designware-core.h"
+
+static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
+{
+	/* Configure Tx/Rx FIFO threshold levels. */
+	regmap_write(dev->map, DW_IC_TX_TL, 0);
+	regmap_write(dev->map, DW_IC_RX_TL, 0);
+
+	/* Configure the I2C slave. */
+	regmap_write(dev->map, DW_IC_CON, dev->slave_cfg);
+	regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK);
+}
+
+/**
+ * i2c_dw_init_slave() - Initialize the designware i2c slave hardware
+ * @dev: device private data
+ *
+ * This function configures and enables the I2C in slave mode.
+ * This function is called during I2C init function, and in case of timeout at
+ * run time.
+ */
+static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
+{
+	int ret;
+
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret)
+		return ret;
+
+	/* Disable the adapter. */
+	__i2c_dw_disable(dev);
+
+	/* Write SDA hold time if supported */
+	if (dev->sda_hold_time)
+		regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);
+
+	i2c_dw_configure_fifo_slave(dev);
+	i2c_dw_release_lock(dev);
+
+	return 0;
+}
+
+static int i2c_dw_reg_slave(struct i2c_client *slave)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
+
+	if (dev->slave)
+		return -EBUSY;
+	if (slave->flags & I2C_CLIENT_TEN)
+		return -EAFNOSUPPORT;
+	pm_runtime_get_sync(dev->dev);
+
+	/*
+	 * Set slave address in the IC_SAR register,
+	 * the address to which the DW_apb_i2c responds.
+	 */
+	__i2c_dw_disable_nowait(dev);
+	regmap_write(dev->map, DW_IC_SAR, slave->addr);
+	dev->slave = slave;
+
+	__i2c_dw_enable(dev);
+
+	dev->cmd_err = 0;
+	dev->msg_write_idx = 0;
+	dev->msg_read_idx = 0;
+	dev->msg_err = 0;
+	dev->status = STATUS_IDLE;
+	dev->abort_source = 0;
+	dev->rx_outstanding = 0;
+
+	return 0;
+}
+
+static int i2c_dw_unreg_slave(struct i2c_client *slave)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
+
+	dev->disable_int(dev);
+	dev->disable(dev);
+	synchronize_irq(dev->irq);
+	dev->slave = NULL;
+	pm_runtime_put(dev->dev);
+
+	return 0;
+}
+
+static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
+{
+	u32 stat, dummy;
+
+	/*
+	 * The IC_INTR_STAT register just indicates "enabled" interrupts.
+	 * The unmasked raw version of interrupt status bits is available
+	 * in the IC_RAW_INTR_STAT register.
+	 *
+	 * That is,
+	 *   stat = readl(IC_INTR_STAT);
+	 * equals to,
+	 *   stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK);
+	 *
+	 * The raw version might be useful for debugging purposes.
+	 */
+	regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
+
+	/*
+	 * Do not use the IC_CLR_INTR register to clear interrupts, or
+	 * you'll miss some interrupts, triggered during the period from
+	 * readl(IC_INTR_STAT) to readl(IC_CLR_INTR).
+	 *
+	 * Instead, use the separately-prepared IC_CLR_* registers.
+	 */
+	if (stat & DW_IC_INTR_TX_ABRT)
+		regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy);
+	if (stat & DW_IC_INTR_RX_UNDER)
+		regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy);
+	if (stat & DW_IC_INTR_RX_OVER)
+		regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy);
+	if (stat & DW_IC_INTR_TX_OVER)
+		regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy);
+	if (stat & DW_IC_INTR_RX_DONE)
+		regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy);
+	if (stat & DW_IC_INTR_ACTIVITY)
+		regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy);
+	if (stat & DW_IC_INTR_STOP_DET)
+		regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy);
+	if (stat & DW_IC_INTR_START_DET)
+		regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy);
+	if (stat & DW_IC_INTR_GEN_CALL)
+		regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy);
+
+	return stat;
+}
+
+/*
+ * Interrupt service routine. This gets called whenever an I2C slave interrupt
+ * occurs.
+ */
+
+static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
+{
+	u32 raw_stat, stat, enabled, tmp;
+	u8 val = 0, slave_activity;
+
+	regmap_read(dev->map, DW_IC_ENABLE, &enabled);
+	regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat);
+	regmap_read(dev->map, DW_IC_STATUS, &tmp);
+	slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
+
+	if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
+		return 0;
+
+	stat = i2c_dw_read_clear_intrbits_slave(dev);
+	dev_dbg(dev->dev,
+		"%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
+		enabled, slave_activity, raw_stat, stat);
+
+	if (stat & DW_IC_INTR_RX_FULL) {
+		if (dev->status != STATUS_WRITE_IN_PROGRESS) {
+			dev->status = STATUS_WRITE_IN_PROGRESS;
+			i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED,
+					&val);
+		}
+
+		regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
+		val = tmp;
+		if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
+				     &val))
+			dev_vdbg(dev->dev, "Byte %X acked!", val);
+	}
+
+	if (stat & DW_IC_INTR_RD_REQ) {
+		if (slave_activity) {
+			regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
+
+			dev->status = STATUS_READ_IN_PROGRESS;
+			if (!i2c_slave_event(dev->slave,
+					     I2C_SLAVE_READ_REQUESTED,
+					     &val))
+				regmap_write(dev->map, DW_IC_DATA_CMD, val);
+		}
+	}
+
+	if (stat & DW_IC_INTR_RX_DONE) {
+		if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
+				     &val))
+			regmap_read(dev->map, DW_IC_CLR_RX_DONE, &tmp);
+	}
+
+	if (stat & DW_IC_INTR_STOP_DET) {
+		dev->status = STATUS_IDLE;
+		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
+	}
+
+	return 1;
+}
+
+static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
+{
+	struct dw_i2c_dev *dev = dev_id;
+	int ret;
+
+	ret = i2c_dw_irq_handler_slave(dev);
+	if (ret > 0)
+		complete(&dev->cmd_complete);
+
+	return IRQ_RETVAL(ret);
+}
+
+static const struct i2c_algorithm i2c_dw_algo = {
+	.functionality = i2c_dw_func,
+	.reg_slave = i2c_dw_reg_slave,
+	.unreg_slave = i2c_dw_unreg_slave,
+};
+
+void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
+{
+	dev->functionality = I2C_FUNC_SLAVE | DW_IC_DEFAULT_FUNCTIONALITY;
+
+	dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL |
+			 DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED;
+
+	dev->mode = DW_IC_SLAVE;
+}
+EXPORT_SYMBOL_GPL(i2c_dw_configure_slave);
+
+int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
+{
+	struct i2c_adapter *adap = &dev->adapter;
+	int ret;
+
+	init_completion(&dev->cmd_complete);
+
+	dev->init = i2c_dw_init_slave;
+	dev->disable = i2c_dw_disable;
+	dev->disable_int = i2c_dw_disable_int;
+
+	ret = i2c_dw_init_regmap(dev);
+	if (ret)
+		return ret;
+
+	ret = i2c_dw_set_sda_hold(dev);
+	if (ret)
+		return ret;
+
+	ret = i2c_dw_set_fifo_size(dev);
+	if (ret)
+		return ret;
+
+	ret = dev->init(dev);
+	if (ret)
+		return ret;
+
+	snprintf(adap->name, sizeof(adap->name),
+		 "Synopsys DesignWare I2C Slave adapter");
+	adap->retries = 3;
+	adap->algo = &i2c_dw_algo;
+	adap->dev.parent = dev->dev;
+	i2c_set_adapdata(adap, dev);
+
+	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
+			       IRQF_SHARED, dev_name(dev->dev), dev);
+	if (ret) {
+		dev_err(dev->dev, "failure requesting irq %i: %d\n",
+			dev->irq, ret);
+		return ret;
+	}
+
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret)
+		dev_err(dev->dev, "failure adding adapter: %d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);
+
+MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
+MODULE_LICENSE("GPL v2");