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// 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 "i2c-designware-core.h"
static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
{
/* Configure Tx/Rx FIFO threshold levels. */
dw_writel(dev, 0, DW_IC_TX_TL);
dw_writel(dev, 0, DW_IC_RX_TL);
/* Configure the I2C slave. */
dw_writel(dev, dev->slave_cfg, DW_IC_CON);
dw_writel(dev, DW_IC_INTR_SLAVE_MASK, DW_IC_INTR_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)
dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
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);
dw_writel(dev, slave->addr, DW_IC_SAR);
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);
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;
/*
* The IC_INTR_STAT register just indicates "enabled" interrupts.
* Ths unmasked raw version of interrupt status bits are available
* in the IC_RAW_INTR_STAT register.
*
* That is,
* stat = dw_readl(IC_INTR_STAT);
* equals to,
* stat = dw_readl(IC_RAW_INTR_STAT) & dw_readl(IC_INTR_MASK);
*
* The raw version might be useful for debugging purposes.
*/
stat = dw_readl(dev, DW_IC_INTR_STAT);
/*
* Do not use the IC_CLR_INTR register to clear interrupts, or
* you'll miss some interrupts, triggered during the period from
* dw_readl(IC_INTR_STAT) to dw_readl(IC_CLR_INTR).
*
* Instead, use the separately-prepared IC_CLR_* registers.
*/
if (stat & DW_IC_INTR_TX_ABRT)
dw_readl(dev, DW_IC_CLR_TX_ABRT);
if (stat & DW_IC_INTR_RX_UNDER)
dw_readl(dev, DW_IC_CLR_RX_UNDER);
if (stat & DW_IC_INTR_RX_OVER)
dw_readl(dev, DW_IC_CLR_RX_OVER);
if (stat & DW_IC_INTR_TX_OVER)
dw_readl(dev, DW_IC_CLR_TX_OVER);
if (stat & DW_IC_INTR_RX_DONE)
dw_readl(dev, DW_IC_CLR_RX_DONE);
if (stat & DW_IC_INTR_ACTIVITY)
dw_readl(dev, DW_IC_CLR_ACTIVITY);
if (stat & DW_IC_INTR_STOP_DET)
dw_readl(dev, DW_IC_CLR_STOP_DET);
if (stat & DW_IC_INTR_START_DET)
dw_readl(dev, DW_IC_CLR_START_DET);
if (stat & DW_IC_INTR_GEN_CALL)
dw_readl(dev, DW_IC_CLR_GEN_CALL);
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;
u8 val, slave_activity;
stat = dw_readl(dev, DW_IC_INTR_STAT);
enabled = dw_readl(dev, DW_IC_ENABLE);
raw_stat = dw_readl(dev, DW_IC_RAW_INTR_STAT);
slave_activity = ((dw_readl(dev, DW_IC_STATUS) &
DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
return 0;
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) && (stat & DW_IC_INTR_STOP_DET))
i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED, &val);
if (stat & DW_IC_INTR_RD_REQ) {
if (slave_activity) {
if (stat & DW_IC_INTR_RX_FULL) {
val = dw_readl(dev, DW_IC_DATA_CMD);
if (!i2c_slave_event(dev->slave,
I2C_SLAVE_WRITE_RECEIVED,
&val)) {
dev_vdbg(dev->dev, "Byte %X acked!",
val);
}
dw_readl(dev, DW_IC_CLR_RD_REQ);
stat = i2c_dw_read_clear_intrbits_slave(dev);
} else {
dw_readl(dev, DW_IC_CLR_RD_REQ);
dw_readl(dev, DW_IC_CLR_RX_UNDER);
stat = i2c_dw_read_clear_intrbits_slave(dev);
}
if (!i2c_slave_event(dev->slave,
I2C_SLAVE_READ_REQUESTED,
&val))
dw_writel(dev, val, DW_IC_DATA_CMD);
}
}
if (stat & DW_IC_INTR_RX_DONE) {
if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
&val))
dw_readl(dev, DW_IC_CLR_RX_DONE);
i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
stat = i2c_dw_read_clear_intrbits_slave(dev);
return 1;
}
if (stat & DW_IC_INTR_RX_FULL) {
val = dw_readl(dev, DW_IC_DATA_CMD);
if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
&val))
dev_vdbg(dev->dev, "Byte %X acked!", val);
} else {
i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
stat = i2c_dw_read_clear_intrbits_slave(dev);
}
return 1;
}
static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
{
struct dw_i2c_dev *dev = dev_id;
int ret;
i2c_dw_read_clear_intrbits_slave(dev);
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,
};
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_set_reg_access(dev);
if (ret)
return ret;
ret = i2c_dw_set_sda_hold(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");
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