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Slave mode driver is based on the concept of i2c-designware driver. Signed-off-by: Juergen Fitschen <me@jue.yt> [ludovic.desroches@microchip.com: rework Kconfig and replace IS_ENABLED by defined] Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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> | ||
|
|
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| #include "i2c-at91.h" | ||
|
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| 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; | ||
| } | ||
|
|
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| static int at91_reg_slave(struct i2c_client *slave) | ||
| { | ||
| struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter); | ||
|
|
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| if (dev->slave) | ||
| return -EBUSY; | ||
|
|
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| if (slave->flags & I2C_CLIENT_TEN) | ||
| return -EAFNOSUPPORT; | ||
|
|
||
| /* Make sure twi_clk doesn't get turned off! */ | ||
| pm_runtime_get_sync(dev->dev); | ||
|
|
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| dev->slave = slave; | ||
| dev->smr = AT91_TWI_SMR_SADR(slave->addr); | ||
|
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| at91_init_twi_bus(dev); | ||
| 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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| static int at91_unreg_slave(struct i2c_client *slave) | ||
| { | ||
| 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; | ||
| 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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| 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; | ||
| } | ||
|
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| static const struct i2c_algorithm at91_twi_algorithm_slave = { | ||
| .reg_slave = at91_reg_slave, | ||
| .unreg_slave = at91_unreg_slave, | ||
| .functionality = at91_twi_func, | ||
| }; | ||
|
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| int at91_twi_probe_slave(struct platform_device *pdev, | ||
| u32 phy_addr, struct at91_twi_dev *dev) | ||
| { | ||
| int rc; | ||
|
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| 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; | ||
| } | ||
|
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| dev->adapter.algo = &at91_twi_algorithm_slave; | ||
|
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| return 0; | ||
| } | ||
|
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| 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); | ||
| } | ||
| } |
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