i2c: at91: added slave mode support (9d3ca54b) · Commits · 戴 / test

drivers/i2c/busses/Kconfig

+13 −0

Original line number	Diff line number	Diff line
		@@ -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

drivers/i2c/busses/Makefile

+3 −0

Original line number	Diff line number	Diff line
		@@ -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

drivers/i2c/busses/i2c-at91-core.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -56,7 +56,9 @@ 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);

		if (dev->slave_detected)
		at91_init_twi_bus_slave(dev);
		else
		at91_init_twi_bus_master(dev);
		}

		@@ -239,6 +241,11 @@ static int at91_twi_probe(struct platform_device *pdev)
		dev->adapter.timeout = AT91_I2C_TIMEOUT;
		dev->adapter.dev.of_node = pdev->dev.of_node;

		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;

drivers/i2c/busses/i2c-at91-slave.c

0 → 100644

+143 −0

Original line number	Diff line number	Diff line
		// 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);
		}
		}

drivers/i2c/busses/i2c-at91.h

+29 −1

Original line number	Diff line number	Diff line
		@@ -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

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