diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-at91-slave.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-at91-slave.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-at91-slave.c b/drivers/i2c/busses/i2c-at91-slave.c new file mode 100644 index 000000000..d6eeea516 --- /dev/null +++ b/drivers/i2c/busses/i2c-at91-slave.c @@ -0,0 +1,143 @@ +// 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); + } +} |