diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index f2c681971201..6b1f6dcdf533 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -387,6 +387,19 @@ config I2C_AT91 the latency to fill the transmission register is too long. If you are facing this situation, use the i2c-gpio driver. +config I2C_AT91_SLAVE_EXPERIMENTAL + tristate "Microchip AT91 I2C experimental slave mode" + depends on I2C_AT91 + select I2C_SLAVE + help + If you say yes to this option, support for the slave mode will be + added. Caution: do not use it for production. This feature has not + been tested in a heavy way, help wanted. + There are known bugs: + - It can hang, on a SAMA5D4, after several transfers. + - There are some mismtaches with a SAMA5D4 as slave and a SAMA5D2 as + master. + config I2C_AU1550 tristate "Au1550/Au1200/Au1300 SMBus interface" depends on MIPS_ALCHEMY diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index ea75a777940e..59b22fbef90a 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -36,6 +36,9 @@ obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o obj-$(CONFIG_I2C_ASPEED) += i2c-aspeed.o obj-$(CONFIG_I2C_AT91) += i2c-at91.o i2c-at91-objs := i2c-at91-core.o i2c-at91-master.o +ifeq ($(CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL),y) + i2c-at91-objs += i2c-at91-slave.o +endif obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o obj-$(CONFIG_I2C_AXXIA) += i2c-axxia.o obj-$(CONFIG_I2C_BCM2835) += i2c-bcm2835.o diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c index 6cb22341fa81..8d55cdd69ff4 100644 --- a/drivers/i2c/busses/i2c-at91-core.c +++ b/drivers/i2c/busses/i2c-at91-core.c @@ -56,8 +56,10 @@ void at91_init_twi_bus(struct at91_twi_dev *dev) { at91_disable_twi_interrupts(dev); at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST); - - at91_init_twi_bus_master(dev); + if (dev->slave_detected) + at91_init_twi_bus_slave(dev); + else + at91_init_twi_bus_master(dev); } static struct at91_twi_pdata at91rm9200_config = { @@ -239,7 +241,12 @@ static int at91_twi_probe(struct platform_device *pdev) dev->adapter.timeout = AT91_I2C_TIMEOUT; dev->adapter.dev.of_node = pdev->dev.of_node; - rc = at91_twi_probe_master(pdev, phy_addr, dev); + dev->slave_detected = i2c_detect_slave_mode(&pdev->dev); + + if (dev->slave_detected) + rc = at91_twi_probe_slave(pdev, phy_addr, dev); + else + rc = at91_twi_probe_master(pdev, phy_addr, dev); if (rc) return rc; diff --git a/drivers/i2c/busses/i2c-at91-slave.c b/drivers/i2c/busses/i2c-at91-slave.c new file mode 100644 index 000000000000..d6eeea5166c0 --- /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 + */ + +#include +#include +#include +#include + +#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); + } +} diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h index 636447498b41..be0e7afda529 100644 --- a/drivers/i2c/busses/i2c-at91.h +++ b/drivers/i2c/busses/i2c-at91.h @@ -49,6 +49,10 @@ #define AT91_TWI_IADRSZ_1 0x0100 /* Internal Device Address Size */ #define AT91_TWI_MREAD BIT(12) /* Master Read Direction */ +#define AT91_TWI_SMR 0x0008 /* Slave Mode Register */ +#define AT91_TWI_SMR_SADR_MAX 0x007f +#define AT91_TWI_SMR_SADR(x) (((x) & AT91_TWI_SMR_SADR_MAX) << 16) + #define AT91_TWI_IADR 0x000c /* Internal Address Register */ #define AT91_TWI_CWGR 0x0010 /* Clock Waveform Generator Reg */ @@ -59,13 +63,17 @@ #define AT91_TWI_TXCOMP BIT(0) /* Transmission Complete */ #define AT91_TWI_RXRDY BIT(1) /* Receive Holding Register Ready */ #define AT91_TWI_TXRDY BIT(2) /* Transmit Holding Register Ready */ +#define AT91_TWI_SVREAD BIT(3) /* Slave Read */ +#define AT91_TWI_SVACC BIT(4) /* Slave Access */ #define AT91_TWI_OVRE BIT(6) /* Overrun Error */ #define AT91_TWI_UNRE BIT(7) /* Underrun Error */ #define AT91_TWI_NACK BIT(8) /* Not Acknowledged */ +#define AT91_TWI_EOSACC BIT(11) /* End Of Slave Access */ #define AT91_TWI_LOCK BIT(23) /* TWI Lock due to Frame Errors */ #define AT91_TWI_INT_MASK \ - (AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK) + (AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \ + | AT91_TWI_SVACC | AT91_TWI_EOSACC) #define AT91_TWI_IER 0x0024 /* Interrupt Enable Register */ #define AT91_TWI_IDR 0x0028 /* Interrupt Disable Register */ @@ -133,6 +141,11 @@ struct at91_twi_dev { bool recv_len_abort; u32 fifo_size; struct at91_twi_dma dma; + bool slave_detected; +#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL + unsigned smr; + struct i2c_client *slave; +#endif }; unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg); @@ -145,3 +158,18 @@ void at91_init_twi_bus(struct at91_twi_dev *dev); void at91_init_twi_bus_master(struct at91_twi_dev *dev); int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr, struct at91_twi_dev *dev); + +#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL +void at91_init_twi_bus_slave(struct at91_twi_dev *dev); +int at91_twi_probe_slave(struct platform_device *pdev, u32 phy_addr, + struct at91_twi_dev *dev); + +#else +static inline void at91_init_twi_bus_slave(struct at91_twi_dev *dev) {} +static inline int at91_twi_probe_slave(struct platform_device *pdev, + u32 phy_addr, struct at91_twi_dev *dev) +{ + return -EINVAL; +} + +#endif