mirror of
https://github.com/physwizz/a155-U-u1.git
synced 2025-10-28 16:15:46 +00:00
144 lines
3.5 KiB
C
144 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* i2c slave support for Atmel's AT91 Two-Wire Interface (TWI)
|
|
*
|
|
* Copyright (C) 2017 Juergen Fitschen <me@jue.yt>
|
|
*/
|
|
|
|
#include <linux/err.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/pm_runtime.h>
|
|
|
|
#include "i2c-at91.h"
|
|
|
|
static irqreturn_t atmel_twi_interrupt_slave(int irq, void *dev_id)
|
|
{
|
|
struct at91_twi_dev *dev = dev_id;
|
|
const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
|
|
const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
|
|
u8 value;
|
|
|
|
if (!irqstatus)
|
|
return IRQ_NONE;
|
|
|
|
/* slave address has been detected on I2C bus */
|
|
if (irqstatus & AT91_TWI_SVACC) {
|
|
if (status & AT91_TWI_SVREAD) {
|
|
i2c_slave_event(dev->slave,
|
|
I2C_SLAVE_READ_REQUESTED, &value);
|
|
writeb_relaxed(value, dev->base + AT91_TWI_THR);
|
|
at91_twi_write(dev, AT91_TWI_IER,
|
|
AT91_TWI_TXRDY | AT91_TWI_EOSACC);
|
|
} else {
|
|
i2c_slave_event(dev->slave,
|
|
I2C_SLAVE_WRITE_REQUESTED, &value);
|
|
at91_twi_write(dev, AT91_TWI_IER,
|
|
AT91_TWI_RXRDY | AT91_TWI_EOSACC);
|
|
}
|
|
at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_SVACC);
|
|
}
|
|
|
|
/* byte transmitted to remote master */
|
|
if (irqstatus & AT91_TWI_TXRDY) {
|
|
i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, &value);
|
|
writeb_relaxed(value, dev->base + AT91_TWI_THR);
|
|
}
|
|
|
|
/* byte received from remote master */
|
|
if (irqstatus & AT91_TWI_RXRDY) {
|
|
value = readb_relaxed(dev->base + AT91_TWI_RHR);
|
|
i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
|
|
}
|
|
|
|
/* master sent stop */
|
|
if (irqstatus & AT91_TWI_EOSACC) {
|
|
at91_twi_write(dev, AT91_TWI_IDR,
|
|
AT91_TWI_TXRDY | AT91_TWI_RXRDY | AT91_TWI_EOSACC);
|
|
at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
|
|
i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &value);
|
|
}
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
static int at91_reg_slave(struct i2c_client *slave)
|
|
{
|
|
struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
|
|
|
|
if (dev->slave)
|
|
return -EBUSY;
|
|
|
|
if (slave->flags & I2C_CLIENT_TEN)
|
|
return -EAFNOSUPPORT;
|
|
|
|
/* Make sure twi_clk doesn't get turned off! */
|
|
pm_runtime_get_sync(dev->dev);
|
|
|
|
dev->slave = slave;
|
|
dev->smr = AT91_TWI_SMR_SADR(slave->addr);
|
|
|
|
at91_init_twi_bus(dev);
|
|
at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
|
|
|
|
dev_info(dev->dev, "entered slave mode (ADR=%d)\n", slave->addr);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int at91_unreg_slave(struct i2c_client *slave)
|
|
{
|
|
struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
|
|
|
|
WARN_ON(!dev->slave);
|
|
|
|
dev_info(dev->dev, "leaving slave mode\n");
|
|
|
|
dev->slave = NULL;
|
|
dev->smr = 0;
|
|
|
|
at91_init_twi_bus(dev);
|
|
|
|
pm_runtime_put(dev->dev);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static u32 at91_twi_func(struct i2c_adapter *adapter)
|
|
{
|
|
return I2C_FUNC_SLAVE | I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
|
|
| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
|
|
}
|
|
|
|
static const struct i2c_algorithm at91_twi_algorithm_slave = {
|
|
.reg_slave = at91_reg_slave,
|
|
.unreg_slave = at91_unreg_slave,
|
|
.functionality = at91_twi_func,
|
|
};
|
|
|
|
int at91_twi_probe_slave(struct platform_device *pdev,
|
|
u32 phy_addr, struct at91_twi_dev *dev)
|
|
{
|
|
int rc;
|
|
|
|
rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt_slave,
|
|
0, dev_name(dev->dev), dev);
|
|
if (rc) {
|
|
dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
|
|
return rc;
|
|
}
|
|
|
|
dev->adapter.algo = &at91_twi_algorithm_slave;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void at91_init_twi_bus_slave(struct at91_twi_dev *dev)
|
|
{
|
|
at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSDIS);
|
|
if (dev->slave_detected && dev->smr) {
|
|
at91_twi_write(dev, AT91_TWI_SMR, dev->smr);
|
|
at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVEN);
|
|
}
|
|
}
|