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