drivers/i2c/busses/i2c-gpio.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Bitbanging I2C bus driver using the GPIO API
  *
  * Copyright (C) 2007 Atmel Corporation
  */
 #include <linux/completion.h>
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/i2c-algo-bit.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/platform_data/i2c-gpio.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/slab.h>

 struct i2c_gpio_private_data {
 	struct gpio_desc *sda;
 	struct gpio_desc *scl;
 	struct i2c_adapter adap;
 	struct i2c_algo_bit_data bit_data;
 	struct i2c_gpio_platform_data pdata;
 #ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
 	/* these must be protected by bus lock */
 	struct completion scl_irq_completion;
 	u64 scl_irq_data;
 #endif
 };

 /*
  * Toggle SDA by changing the output value of the pin. This is only
  * valid for pins configured as open drain (i.e. setting the value
  * high effectively turns off the output driver.)
  */
 static void i2c_gpio_setsda_val(void *data, int state)
 {
 	struct i2c_gpio_private_data *priv = data;

 	gpiod_set_value_cansleep(priv->sda, state);
 }

 /*
  * Toggle SCL by changing the output value of the pin. This is used
  * for pins that are configured as open drain and for output-only
  * pins. The latter case will break the i2c protocol, but it will
  * often work in practice.
  */
 static void i2c_gpio_setscl_val(void *data, int state)
 {
 	struct i2c_gpio_private_data *priv = data;

 	gpiod_set_value_cansleep(priv->scl, state);
 }

 static int i2c_gpio_getsda(void *data)
 {
 	struct i2c_gpio_private_data *priv = data;

 	return gpiod_get_value_cansleep(priv->sda);
 }

 static int i2c_gpio_getscl(void *data)
 {
 	struct i2c_gpio_private_data *priv = data;

 	return gpiod_get_value_cansleep(priv->scl);
 }

 #ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR

 #define setsda(bd, val)	((bd)->setsda((bd)->data, val))
 #define setscl(bd, val)	((bd)->setscl((bd)->data, val))
 #define getsda(bd)	((bd)->getsda((bd)->data))
 #define getscl(bd)	((bd)->getscl((bd)->data))

 #define WIRE_ATTRIBUTE(wire) \
 static int fops_##wire##_get(void *data, u64 *val)		\
 {								\
 	struct i2c_gpio_private_data *priv = data;		\
 								\
 	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
 	*val = get##wire(&priv->bit_data);			\
 	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
 	return 0;						\
 }								\
 static int fops_##wire##_set(void *data, u64 val)		\
 {								\
 	struct i2c_gpio_private_data *priv = data;		\
 								\
 	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
 	set##wire(&priv->bit_data, val);			\
 	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
 	return 0;						\
 }								\
 DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")

 WIRE_ATTRIBUTE(scl);
 WIRE_ATTRIBUTE(sda);

 static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
 					u32 pattern, u8 pattern_size)
 {
 	struct i2c_algo_bit_data *bit_data = &priv->bit_data;
 	int i;

 	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

 	/* START condition */
 	setsda(bit_data, 0);
 	udelay(bit_data->udelay);

 	/* Send pattern, request ACK, don't send STOP */
 	for (i = pattern_size - 1; i >= 0; i--) {
 		setscl(bit_data, 0);
 		udelay(bit_data->udelay / 2);
 		setsda(bit_data, (pattern >> i) & 1);
 		udelay((bit_data->udelay + 1) / 2);
 		setscl(bit_data, 1);
 		udelay(bit_data->udelay);
 	}

 	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
 }

 static int fops_incomplete_addr_phase_set(void *data, u64 addr)
 {
 	struct i2c_gpio_private_data *priv = data;
 	u32 pattern;

 	if (addr > 0x7f)
 		return -EINVAL;

 	/* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
 	pattern = (addr << 2) | 3;

 	i2c_gpio_incomplete_transfer(priv, pattern, 9);

 	return 0;
 }
 DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");

 static int fops_incomplete_write_byte_set(void *data, u64 addr)
 {
 	struct i2c_gpio_private_data *priv = data;
 	u32 pattern;

 	if (addr > 0x7f)
 		return -EINVAL;

 	/* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
 	pattern = (addr << 2) | 1;
 	/* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
 	pattern = (pattern << 9) | 1;

 	i2c_gpio_incomplete_transfer(priv, pattern, 18);

 	return 0;
 }
 DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");

 static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
 				       irqreturn_t handler(int, void*))
 {
 	int ret, irq = gpiod_to_irq(priv->scl);

 	if (irq < 0)
 		return irq;

 	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

 	ret = gpiod_direction_input(priv->scl);
 	if (ret)
 		goto unlock;

 	reinit_completion(&priv->scl_irq_completion);

 	ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
 			  "i2c_gpio_fault_injector_scl_irq", priv);
 	if (ret)
 		goto output;

 	wait_for_completion_interruptible(&priv->scl_irq_completion);

 	free_irq(irq, priv);
  output:
 	ret = gpiod_direction_output(priv->scl, 1) ?: ret;
  unlock:
 	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

 	return ret;
 }

 static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
 {
 	struct i2c_gpio_private_data *priv = dev_id;

 	setsda(&priv->bit_data, 0);
 	udelay(priv->scl_irq_data);
 	setsda(&priv->bit_data, 1);

 	complete(&priv->scl_irq_completion);

 	return IRQ_HANDLED;
 }

 static int fops_lose_arbitration_set(void *data, u64 duration)
 {
 	struct i2c_gpio_private_data *priv = data;

 	if (duration > 100 * 1000)
 		return -EINVAL;

 	priv->scl_irq_data = duration;
 	/*
 	 * Interrupt on falling SCL. This ensures that the controller under test
 	 * has really started the transfer. Interrupt on falling SDA did only
 	 * exercise 'bus busy' detection on some HW but not 'arbitration lost'.
 	 * Note that the interrupt latency may cause the first bits to be
 	 * transmitted correctly.
 	 */
 	return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
 }
 DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");

 static irqreturn_t inject_panic_irq(int irq, void *dev_id)
 {
 	struct i2c_gpio_private_data *priv = dev_id;

 	udelay(priv->scl_irq_data);
 	panic("I2C fault injector induced panic");

 	return IRQ_HANDLED;
 }

 static int fops_inject_panic_set(void *data, u64 duration)
 {
 	struct i2c_gpio_private_data *priv = data;

 	if (duration > 100 * 1000)
 		return -EINVAL;

 	priv->scl_irq_data = duration;
 	/*
 	 * Interrupt on falling SCL. This ensures that the controller under test
 	 * has really started the transfer.
 	 */
 	return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
 }
 DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");

 static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
 {
 	struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);

 	init_completion(&priv->scl_irq_completion);

 	debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->adap.debugfs,
 				   priv, &fops_incomplete_addr_phase);
 	debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->adap.debugfs,
 				   priv, &fops_incomplete_write_byte);
 	if (priv->bit_data.getscl) {
 		debugfs_create_file_unsafe("inject_panic", 0200, priv->adap.debugfs,
 					   priv, &fops_inject_panic);
 		debugfs_create_file_unsafe("lose_arbitration", 0200, priv->adap.debugfs,
 					   priv, &fops_lose_arbitration);
 	}
 	debugfs_create_file_unsafe("scl", 0600, priv->adap.debugfs, priv, &fops_scl);
 	debugfs_create_file_unsafe("sda", 0600, priv->adap.debugfs, priv, &fops_sda);
 }
 #else
 static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
 #endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/

 /* Get i2c-gpio properties from DT or ACPI table */
 static void i2c_gpio_get_properties(struct device *dev,
 				    struct i2c_gpio_platform_data *pdata)
 {
 	u32 reg;

 	device_property_read_u32(dev, "i2c-gpio,delay-us", &pdata->udelay);

 	if (!device_property_read_u32(dev, "i2c-gpio,timeout-ms", &reg))
 		pdata->timeout = msecs_to_jiffies(reg);

 	pdata->sda_is_open_drain =
 		device_property_read_bool(dev, "i2c-gpio,sda-open-drain");
 	pdata->scl_is_open_drain =
 		device_property_read_bool(dev, "i2c-gpio,scl-open-drain");
 	pdata->scl_is_output_only =
 		device_property_read_bool(dev, "i2c-gpio,scl-output-only");
 	pdata->sda_is_output_only =
 		device_property_read_bool(dev, "i2c-gpio,sda-output-only");
 	pdata->sda_has_no_pullup =
 		device_property_read_bool(dev, "i2c-gpio,sda-has-no-pullup");
 	pdata->scl_has_no_pullup =
 		device_property_read_bool(dev, "i2c-gpio,scl-has-no-pullup");
 }

 static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
 					   const char *con_id,
 					   unsigned int index,
 					   enum gpiod_flags gflags)
 {
 	struct gpio_desc *retdesc;
 	int ret;

 	retdesc = devm_gpiod_get(dev, con_id, gflags);
 	if (!IS_ERR(retdesc)) {
 		dev_dbg(dev, "got GPIO from name %s\n", con_id);
 		return retdesc;
 	}

 	retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
 	if (!IS_ERR(retdesc)) {
 		dev_dbg(dev, "got GPIO from index %u\n", index);
 		return retdesc;
 	}

 	ret = PTR_ERR(retdesc);

 	/* FIXME: hack in the old code, is this really necessary? */
 	if (ret == -EINVAL)
 		retdesc = ERR_PTR(-EPROBE_DEFER);

 	/* This happens if the GPIO driver is not yet probed, let's defer */
 	if (ret == -ENOENT)
 		retdesc = ERR_PTR(-EPROBE_DEFER);

 	if (PTR_ERR(retdesc) != -EPROBE_DEFER)
 		dev_err(dev, "error trying to get descriptor: %d\n", ret);

 	return retdesc;
 }

 static int i2c_gpio_probe(struct platform_device *pdev)
 {
 	struct i2c_gpio_private_data *priv;
 	struct i2c_gpio_platform_data *pdata;
 	struct i2c_algo_bit_data *bit_data;
 	struct i2c_adapter *adap;
 	struct device *dev = &pdev->dev;
 	struct fwnode_handle *fwnode = dev_fwnode(dev);
 	enum gpiod_flags gflags;
 	int ret;

 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	adap = &priv->adap;
 	bit_data = &priv->bit_data;
 	pdata = &priv->pdata;

 	if (fwnode) {
 		i2c_gpio_get_properties(dev, pdata);
 	} else {
 		/*
 		 * If all platform data settings are zero it is OK
 		 * to not provide any platform data from the board.
 		 */
 		if (dev_get_platdata(dev))
 			memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
 	}

 	/*
 	 * First get the GPIO pins; if it fails, we'll defer the probe.
 	 * If the SCL/SDA lines are marked "open drain" by platform data or
 	 * device tree then this means that something outside of our control is
 	 * marking these lines to be handled as open drain, and we should just
 	 * handle them as we handle any other output. Else we enforce open
 	 * drain as this is required for an I2C bus.
 	 */
 	if (pdata->sda_is_open_drain || pdata->sda_has_no_pullup)
 		gflags = GPIOD_OUT_HIGH;
 	else
 		gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
 	priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
 	if (IS_ERR(priv->sda))
 		return PTR_ERR(priv->sda);

 	if (pdata->scl_is_open_drain || pdata->scl_has_no_pullup)
 		gflags = GPIOD_OUT_HIGH;
 	else
 		gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
 	priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
 	if (IS_ERR(priv->scl))
 		return PTR_ERR(priv->scl);

 	if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
 		dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
 	else
 		bit_data->can_do_atomic = true;

 	bit_data->setsda = i2c_gpio_setsda_val;
 	bit_data->setscl = i2c_gpio_setscl_val;

 	if (!pdata->scl_is_output_only)
 		bit_data->getscl = i2c_gpio_getscl;
 	if (!pdata->sda_is_output_only)
 		bit_data->getsda = i2c_gpio_getsda;

 	if (pdata->udelay)
 		bit_data->udelay = pdata->udelay;
 	else if (pdata->scl_is_output_only)
 		bit_data->udelay = 50;			/* 10 kHz */
 	else
 		bit_data->udelay = 5;			/* 100 kHz */

 	if (pdata->timeout)
 		bit_data->timeout = pdata->timeout;
 	else
 		bit_data->timeout = HZ / 10;		/* 100 ms */

 	bit_data->data = priv;

 	adap->owner = THIS_MODULE;
 	if (fwnode)
 		strscpy(adap->name, dev_name(dev), sizeof(adap->name));
 	else
 		snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);

 	adap->algo_data = bit_data;
 	adap->class = I2C_CLASS_HWMON;
 	adap->dev.parent = dev;
 	device_set_node(&adap->dev, fwnode);

 	adap->nr = pdev->id;
 	ret = i2c_bit_add_numbered_bus(adap);
 	if (ret)
 		return ret;

 	platform_set_drvdata(pdev, priv);

 	/*
 	 * FIXME: using global GPIO numbers is not helpful. If/when we
 	 * get accessors to get the actual name of the GPIO line,
 	 * from the descriptor, then provide that instead.
 	 */
 	dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
 		 desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
 		 pdata->scl_is_output_only
 		 ? ", no clock stretching" : "");

 	i2c_gpio_fault_injector_init(pdev);

 	return 0;
 }

 static void i2c_gpio_remove(struct platform_device *pdev)
 {
 	struct i2c_gpio_private_data *priv;
 	struct i2c_adapter *adap;

 	priv = platform_get_drvdata(pdev);
 	adap = &priv->adap;

 	i2c_del_adapter(adap);
 }

 static const struct of_device_id i2c_gpio_dt_ids[] = {
 	{ .compatible = "i2c-gpio", },
 	{ /* sentinel */ }
 };

 MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);

 static const struct acpi_device_id i2c_gpio_acpi_match[] = {
 	{ "LOON0005" }, /* LoongArch */
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, i2c_gpio_acpi_match);

 static struct platform_driver i2c_gpio_driver = {
 	.driver		= {
 		.name	= "i2c-gpio",
 		.of_match_table	= i2c_gpio_dt_ids,
 		.acpi_match_table = i2c_gpio_acpi_match,
 	},
 	.probe		= i2c_gpio_probe,
 	.remove_new	= i2c_gpio_remove,
 };

 static int __init i2c_gpio_init(void)
 {
 	int ret;

 	ret = platform_driver_register(&i2c_gpio_driver);
 	if (ret)
 		printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);

 	return ret;
 }
 subsys_initcall(i2c_gpio_init);

 static void __exit i2c_gpio_exit(void)
 {
 	platform_driver_unregister(&i2c_gpio_driver);
 }
 module_exit(i2c_gpio_exit);

 MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
 MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:i2c-gpio");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Bitbanging I2C bus driver using the GPIO API
	*
	* Copyright (C) 2007 Atmel Corporation
	*/
	#include <linux/completion.h>
	#include <linux/debugfs.h>
	#include <linux/delay.h>
	#include <linux/gpio/consumer.h>
	#include <linux/i2c-algo-bit.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/platform_data/i2c-gpio.h>
	#include <linux/platform_device.h>
	#include <linux/property.h>
	#include <linux/slab.h>

	struct i2c_gpio_private_data {
	struct gpio_desc *sda;
	struct gpio_desc *scl;
	struct i2c_adapter adap;
	struct i2c_algo_bit_data bit_data;
	struct i2c_gpio_platform_data pdata;
	#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
	/* these must be protected by bus lock */
	struct completion scl_irq_completion;
	u64 scl_irq_data;
	#endif
	};

	/*
	* Toggle SDA by changing the output value of the pin. This is only
	* valid for pins configured as open drain (i.e. setting the value
	* high effectively turns off the output driver.)
	*/
	static void i2c_gpio_setsda_val(void *data, int state)
	{
	struct i2c_gpio_private_data *priv = data;

	gpiod_set_value_cansleep(priv->sda, state);
	}

	/*
	* Toggle SCL by changing the output value of the pin. This is used
	* for pins that are configured as open drain and for output-only
	* pins. The latter case will break the i2c protocol, but it will
	* often work in practice.
	*/
	static void i2c_gpio_setscl_val(void *data, int state)
	{
	struct i2c_gpio_private_data *priv = data;

	gpiod_set_value_cansleep(priv->scl, state);
	}

	static int i2c_gpio_getsda(void *data)
	{
	struct i2c_gpio_private_data *priv = data;

	return gpiod_get_value_cansleep(priv->sda);
	}

	static int i2c_gpio_getscl(void *data)
	{
	struct i2c_gpio_private_data *priv = data;

	return gpiod_get_value_cansleep(priv->scl);
	}

	#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR

	#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
	#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
	#define getsda(bd) ((bd)->getsda((bd)->data))
	#define getscl(bd) ((bd)->getscl((bd)->data))

	#define WIRE_ATTRIBUTE(wire) \
	static int fops_##wire##_get(void data, u64 val) \
	{ \
	struct i2c_gpio_private_data *priv = data; \
	\
	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	*val = get##wire(&priv->bit_data); \
	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	return 0; \
	} \
	static int fops_##wire##_set(void *data, u64 val) \
	{ \
	struct i2c_gpio_private_data *priv = data; \
	\
	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	set##wire(&priv->bit_data, val); \
	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	return 0; \
	} \
	DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")

	WIRE_ATTRIBUTE(scl);
	WIRE_ATTRIBUTE(sda);

	static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
	u32 pattern, u8 pattern_size)
	{
	struct i2c_algo_bit_data *bit_data = &priv->bit_data;
	int i;

	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

	/* START condition */
	setsda(bit_data, 0);
	udelay(bit_data->udelay);

	/* Send pattern, request ACK, don't send STOP */
	for (i = pattern_size - 1; i >= 0; i--) {
	setscl(bit_data, 0);
	udelay(bit_data->udelay / 2);
	setsda(bit_data, (pattern >> i) & 1);
	udelay((bit_data->udelay + 1) / 2);
	setscl(bit_data, 1);
	udelay(bit_data->udelay);
	}

	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
	}

	static int fops_incomplete_addr_phase_set(void *data, u64 addr)
	{
	struct i2c_gpio_private_data *priv = data;
	u32 pattern;

	if (addr > 0x7f)
	return -EINVAL;

	/* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
	pattern = (addr << 2) \| 3;

	i2c_gpio_incomplete_transfer(priv, pattern, 9);

	return 0;
	}
	DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");

	static int fops_incomplete_write_byte_set(void *data, u64 addr)
	{
	struct i2c_gpio_private_data *priv = data;
	u32 pattern;

	if (addr > 0x7f)
	return -EINVAL;

	/* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
	pattern = (addr << 2) \| 1;
	/* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
	pattern = (pattern << 9) \| 1;

	i2c_gpio_incomplete_transfer(priv, pattern, 18);

	return 0;
	}
	DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");

	static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
	irqreturn_t handler(int, void*))
	{
	int ret, irq = gpiod_to_irq(priv->scl);

	if (irq < 0)
	return irq;

	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

	ret = gpiod_direction_input(priv->scl);
	if (ret)
	goto unlock;

	reinit_completion(&priv->scl_irq_completion);

	ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
	"i2c_gpio_fault_injector_scl_irq", priv);
	if (ret)
	goto output;

	wait_for_completion_interruptible(&priv->scl_irq_completion);

	free_irq(irq, priv);
	output:
	ret = gpiod_direction_output(priv->scl, 1) ?: ret;
	unlock:
	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

	return ret;
	}

	static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
	{
	struct i2c_gpio_private_data *priv = dev_id;

	setsda(&priv->bit_data, 0);
	udelay(priv->scl_irq_data);
	setsda(&priv->bit_data, 1);

	complete(&priv->scl_irq_completion);

	return IRQ_HANDLED;
	}

	static int fops_lose_arbitration_set(void *data, u64 duration)
	{
	struct i2c_gpio_private_data *priv = data;

	if (duration > 100 * 1000)
	return -EINVAL;

	priv->scl_irq_data = duration;
	/*
	* Interrupt on falling SCL. This ensures that the controller under test
	* has really started the transfer. Interrupt on falling SDA did only
	* exercise 'bus busy' detection on some HW but not 'arbitration lost'.
	* Note that the interrupt latency may cause the first bits to be
	* transmitted correctly.
	*/
	return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
	}
	DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");

	static irqreturn_t inject_panic_irq(int irq, void *dev_id)
	{
	struct i2c_gpio_private_data *priv = dev_id;

	udelay(priv->scl_irq_data);
	panic("I2C fault injector induced panic");

	return IRQ_HANDLED;
	}

	static int fops_inject_panic_set(void *data, u64 duration)
	{
	struct i2c_gpio_private_data *priv = data;

	if (duration > 100 * 1000)
	return -EINVAL;

	priv->scl_irq_data = duration;
	/*
	* Interrupt on falling SCL. This ensures that the controller under test
	* has really started the transfer.
	*/
	return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
	}
	DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");

	static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
	{
	struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);

	init_completion(&priv->scl_irq_completion);

	debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->adap.debugfs,
	priv, &fops_incomplete_addr_phase);
	debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->adap.debugfs,
	priv, &fops_incomplete_write_byte);
	if (priv->bit_data.getscl) {
	debugfs_create_file_unsafe("inject_panic", 0200, priv->adap.debugfs,
	priv, &fops_inject_panic);
	debugfs_create_file_unsafe("lose_arbitration", 0200, priv->adap.debugfs,
	priv, &fops_lose_arbitration);
	}
	debugfs_create_file_unsafe("scl", 0600, priv->adap.debugfs, priv, &fops_scl);
	debugfs_create_file_unsafe("sda", 0600, priv->adap.debugfs, priv, &fops_sda);
	}
	#else
	static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
	#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/

	/* Get i2c-gpio properties from DT or ACPI table */
	static void i2c_gpio_get_properties(struct device *dev,
	struct i2c_gpio_platform_data *pdata)
	{
	u32 reg;

	device_property_read_u32(dev, "i2c-gpio,delay-us", &pdata->udelay);

	if (!device_property_read_u32(dev, "i2c-gpio,timeout-ms", &reg))
	pdata->timeout = msecs_to_jiffies(reg);

	pdata->sda_is_open_drain =
	device_property_read_bool(dev, "i2c-gpio,sda-open-drain");
	pdata->scl_is_open_drain =
	device_property_read_bool(dev, "i2c-gpio,scl-open-drain");
	pdata->scl_is_output_only =
	device_property_read_bool(dev, "i2c-gpio,scl-output-only");
	pdata->sda_is_output_only =
	device_property_read_bool(dev, "i2c-gpio,sda-output-only");
	pdata->sda_has_no_pullup =
	device_property_read_bool(dev, "i2c-gpio,sda-has-no-pullup");
	pdata->scl_has_no_pullup =
	device_property_read_bool(dev, "i2c-gpio,scl-has-no-pullup");
	}

	static struct gpio_desc i2c_gpio_get_desc(struct device dev,
	const char *con_id,
	unsigned int index,
	enum gpiod_flags gflags)
	{
	struct gpio_desc *retdesc;
	int ret;

	retdesc = devm_gpiod_get(dev, con_id, gflags);
	if (!IS_ERR(retdesc)) {
	dev_dbg(dev, "got GPIO from name %s\n", con_id);
	return retdesc;
	}

	retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
	if (!IS_ERR(retdesc)) {
	dev_dbg(dev, "got GPIO from index %u\n", index);
	return retdesc;
	}

	ret = PTR_ERR(retdesc);

	/* FIXME: hack in the old code, is this really necessary? */
	if (ret == -EINVAL)
	retdesc = ERR_PTR(-EPROBE_DEFER);

	/* This happens if the GPIO driver is not yet probed, let's defer */
	if (ret == -ENOENT)
	retdesc = ERR_PTR(-EPROBE_DEFER);

	if (PTR_ERR(retdesc) != -EPROBE_DEFER)
	dev_err(dev, "error trying to get descriptor: %d\n", ret);

	return retdesc;
	}

	static int i2c_gpio_probe(struct platform_device *pdev)
	{
	struct i2c_gpio_private_data *priv;
	struct i2c_gpio_platform_data *pdata;
	struct i2c_algo_bit_data *bit_data;
	struct i2c_adapter *adap;
	struct device *dev = &pdev->dev;
	struct fwnode_handle *fwnode = dev_fwnode(dev);
	enum gpiod_flags gflags;
	int ret;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	adap = &priv->adap;
	bit_data = &priv->bit_data;
	pdata = &priv->pdata;

	if (fwnode) {
	i2c_gpio_get_properties(dev, pdata);
	} else {
	/*
	* If all platform data settings are zero it is OK
	* to not provide any platform data from the board.
	*/
	if (dev_get_platdata(dev))
	memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
	}

	/*
	* First get the GPIO pins; if it fails, we'll defer the probe.
	* If the SCL/SDA lines are marked "open drain" by platform data or
	* device tree then this means that something outside of our control is
	* marking these lines to be handled as open drain, and we should just
	* handle them as we handle any other output. Else we enforce open
	* drain as this is required for an I2C bus.
	*/
	if (pdata->sda_is_open_drain \|\| pdata->sda_has_no_pullup)
	gflags = GPIOD_OUT_HIGH;
	else
	gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
	priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
	if (IS_ERR(priv->sda))
	return PTR_ERR(priv->sda);

	if (pdata->scl_is_open_drain \|\| pdata->scl_has_no_pullup)
	gflags = GPIOD_OUT_HIGH;
	else
	gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
	priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
	if (IS_ERR(priv->scl))
	return PTR_ERR(priv->scl);

	if (gpiod_cansleep(priv->sda) \|\| gpiod_cansleep(priv->scl))
	dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
	else
	bit_data->can_do_atomic = true;

	bit_data->setsda = i2c_gpio_setsda_val;
	bit_data->setscl = i2c_gpio_setscl_val;

	if (!pdata->scl_is_output_only)
	bit_data->getscl = i2c_gpio_getscl;
	if (!pdata->sda_is_output_only)
	bit_data->getsda = i2c_gpio_getsda;

	if (pdata->udelay)
	bit_data->udelay = pdata->udelay;
	else if (pdata->scl_is_output_only)
	bit_data->udelay = 50; /* 10 kHz */
	else
	bit_data->udelay = 5; /* 100 kHz */

	if (pdata->timeout)
	bit_data->timeout = pdata->timeout;
	else
	bit_data->timeout = HZ / 10; /* 100 ms */

	bit_data->data = priv;

	adap->owner = THIS_MODULE;
	if (fwnode)
	strscpy(adap->name, dev_name(dev), sizeof(adap->name));
	else
	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);

	adap->algo_data = bit_data;
	adap->class = I2C_CLASS_HWMON;
	adap->dev.parent = dev;
	device_set_node(&adap->dev, fwnode);

	adap->nr = pdev->id;
	ret = i2c_bit_add_numbered_bus(adap);
	if (ret)
	return ret;

	platform_set_drvdata(pdev, priv);

	/*
	* FIXME: using global GPIO numbers is not helpful. If/when we
	* get accessors to get the actual name of the GPIO line,
	* from the descriptor, then provide that instead.
	*/
	dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
	desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
	pdata->scl_is_output_only
	? ", no clock stretching" : "");

	i2c_gpio_fault_injector_init(pdev);

	return 0;
	}

	static void i2c_gpio_remove(struct platform_device *pdev)
	{
	struct i2c_gpio_private_data *priv;
	struct i2c_adapter *adap;

	priv = platform_get_drvdata(pdev);
	adap = &priv->adap;

	i2c_del_adapter(adap);
	}

	static const struct of_device_id i2c_gpio_dt_ids[] = {
	{ .compatible = "i2c-gpio", },
	{ /* sentinel */ }
	};

	MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);

	static const struct acpi_device_id i2c_gpio_acpi_match[] = {
	{ "LOON0005" }, /* LoongArch */
	{ }
	};
	MODULE_DEVICE_TABLE(acpi, i2c_gpio_acpi_match);

	static struct platform_driver i2c_gpio_driver = {
	.driver = {
	.name = "i2c-gpio",
	.of_match_table = i2c_gpio_dt_ids,
	.acpi_match_table = i2c_gpio_acpi_match,
	},
	.probe = i2c_gpio_probe,
	.remove_new = i2c_gpio_remove,
	};

	static int __init i2c_gpio_init(void)
	{
	int ret;

	ret = platform_driver_register(&i2c_gpio_driver);
	if (ret)
	printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);

	return ret;
	}
	subsys_initcall(i2c_gpio_init);

	static void __exit i2c_gpio_exit(void)
	{
	platform_driver_unregister(&i2c_gpio_driver);
	}
	module_exit(i2c_gpio_exit);

	MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
	MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:i2c-gpio");