[linux-block.git] / drivers / i2c / busses / i2c-gpio.c

// 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
	struct dentry *debug_dir;
	/* 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
static struct dentry *i2c_gpio_debug_dir;

#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 master 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 master 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);

	/*
	 * If there will be a debugfs-dir per i2c adapter somewhen, put the
	 * 'fault-injector' dir there. Until then, we have a global dir with
	 * all adapters as subdirs.
	 */
	if (!i2c_gpio_debug_dir)
		i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);

	priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);

	init_completion(&priv->scl_irq_completion);

	debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
				   priv, &fops_incomplete_addr_phase);
	debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
				   priv, &fops_incomplete_write_byte);
	if (priv->bit_data.getscl) {
		debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir,
					   priv, &fops_inject_panic);
		debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir,
					   priv, &fops_lose_arbitration);
	}
	debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
	debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
}

static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
{
	struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);

	debugfs_remove_recursive(priv->debug_dir);
}
#else
static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
static inline void i2c_gpio_fault_injector_exit(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;

	i2c_gpio_fault_injector_exit(pdev);

	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");
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
1c23af90 HS	2	/*
	3	* Bitbanging I2C bus driver using the GPIO API
	4	*
	5	* Copyright (C) 2007 Atmel Corporation
1c23af90	6	*/
63e57b6f	7	#include <linux/completion.h>
14911c6f WS	8	#include <linux/debugfs.h>
14911c6f WS	9	#include <linux/delay.h>
2f8aa465	10	#include <linux/gpio/consumer.h>
1c23af90	11	#include <linux/i2c-algo-bit.h>
2f8aa465	12	#include <linux/i2c.h>
1c23af90	13	#include <linux/init.h>
63e57b6f	14	#include <linux/interrupt.h>
1c23af90	15	#include <linux/module.h>
2f8aa465 WS	16	#include <linux/platform_data/i2c-gpio.h>
2f8aa465 WS	17	#include <linux/platform_device.h>
7b6e9dc7	18	#include <linux/property.h>
2f8aa465	19	#include <linux/slab.h>
8ffaa0f4 JCPV	20
8ffaa0f4 JCPV	21	struct i2c_gpio_private_data {
b2e63555 LW	22	struct gpio_desc *sda;
b2e63555 LW	23	struct gpio_desc *scl;
8ffaa0f4 JCPV	24	struct i2c_adapter adap;
	25	struct i2c_algo_bit_data bit_data;
	26	struct i2c_gpio_platform_data pdata;
14911c6f WS	27	#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
14911c6f WS	28	struct dentry *debug_dir;
63e57b6f WS	29	/* these must be protected by bus lock */
	30	struct completion scl_irq_completion;
	31	u64 scl_irq_data;
14911c6f	32	#endif
8ffaa0f4	33	};
1c23af90	34
1c23af90 HS	35	/*
	36	* Toggle SDA by changing the output value of the pin. This is only
	37	* valid for pins configured as open drain (i.e. setting the value
	38	* high effectively turns off the output driver.)
	39	*/
	40	static void i2c_gpio_setsda_val(void *data, int state)
	41	{
b2e63555	42	struct i2c_gpio_private_data *priv = data;
1c23af90	43
f11a0446	44	gpiod_set_value_cansleep(priv->sda, state);
1c23af90 HS	45	}
1c23af90 HS	46
1c23af90 HS	47	/*
	48	* Toggle SCL by changing the output value of the pin. This is used
	49	* for pins that are configured as open drain and for output-only
	50	* pins. The latter case will break the i2c protocol, but it will
	51	* often work in practice.
	52	*/
	53	static void i2c_gpio_setscl_val(void *data, int state)
	54	{
b2e63555	55	struct i2c_gpio_private_data *priv = data;
1c23af90	56
f11a0446	57	gpiod_set_value_cansleep(priv->scl, state);
1c23af90 HS	58	}
1c23af90 HS	59
4d6ceed4	60	static int i2c_gpio_getsda(void *data)
1c23af90	61	{
b2e63555	62	struct i2c_gpio_private_data *priv = data;
1c23af90	63
f11a0446	64	return gpiod_get_value_cansleep(priv->sda);
1c23af90 HS	65	}
1c23af90 HS	66
4d6ceed4	67	static int i2c_gpio_getscl(void *data)
1c23af90	68	{
b2e63555	69	struct i2c_gpio_private_data *priv = data;
1c23af90	70
f11a0446	71	return gpiod_get_value_cansleep(priv->scl);
1b295c83 JD	72	}
1b295c83 JD	73
14911c6f WS	74	#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
	75	static struct dentry *i2c_gpio_debug_dir;
	76
	77	#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
	78	#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
	79	#define getsda(bd) ((bd)->getsda((bd)->data))
	80	#define getscl(bd) ((bd)->getscl((bd)->data))
	81
	82	#define WIRE_ATTRIBUTE(wire) \
3f3a89e1 PR	83	static int fops_##wire##_get(void data, u64 val) \
	84	{ \
	85	struct i2c_gpio_private_data *priv = data; \
	86	\
	87	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	88	*val = get##wire(&priv->bit_data); \
	89	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	90	return 0; \
	91	} \
	92	static int fops_##wire##_set(void *data, u64 val) \
	93	{ \
	94	struct i2c_gpio_private_data *priv = data; \
	95	\
	96	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	97	set##wire(&priv->bit_data, val); \
	98	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
	99	return 0; \
	100	} \
14911c6f WS	101	DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")
	102
	103	WIRE_ATTRIBUTE(scl);
	104	WIRE_ATTRIBUTE(sda);
	105
16d55daa WS	106	static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
16d55daa WS	107	u32 pattern, u8 pattern_size)
14911c6f	108	{
14911c6f	109	struct i2c_algo_bit_data *bit_data = &priv->bit_data;
16d55daa	110	int i;
14911c6f	111
3f3a89e1	112	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
14911c6f WS	113
	114	/* START condition */
	115	setsda(bit_data, 0);
	116	udelay(bit_data->udelay);
	117
16d55daa WS	118	/* Send pattern, request ACK, don't send STOP */
16d55daa WS	119	for (i = pattern_size - 1; i >= 0; i--) {
14911c6f WS	120	setscl(bit_data, 0);
	121	udelay(bit_data->udelay / 2);
	122	setsda(bit_data, (pattern >> i) & 1);
	123	udelay((bit_data->udelay + 1) / 2);
	124	setscl(bit_data, 1);
	125	udelay(bit_data->udelay);
	126	}
	127
3f3a89e1	128	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
16d55daa WS	129	}
	130
	131	static int fops_incomplete_addr_phase_set(void *data, u64 addr)
	132	{
	133	struct i2c_gpio_private_data *priv = data;
	134	u32 pattern;
	135
	136	if (addr > 0x7f)
	137	return -EINVAL;
	138
	139	/* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
	140	pattern = (addr << 2) \| 3;
	141
	142	i2c_gpio_incomplete_transfer(priv, pattern, 9);
14911c6f WS	143
	144	return 0;
	145	}
16d55daa	146	DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");
14911c6f	147
bbe89970 WS	148	static int fops_incomplete_write_byte_set(void *data, u64 addr)
	149	{
	150	struct i2c_gpio_private_data *priv = data;
	151	u32 pattern;
	152
	153	if (addr > 0x7f)
	154	return -EINVAL;
	155
	156	/* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
	157	pattern = (addr << 2) \| 1;
	158	/* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
	159	pattern = (pattern << 9) \| 1;
	160
	161	i2c_gpio_incomplete_transfer(priv, pattern, 18);
	162
	163	return 0;
	164	}
	165	DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");
	166
63e57b6f WS	167	static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
	168	irqreturn_t handler(int, void*))
	169	{
	170	int ret, irq = gpiod_to_irq(priv->scl);
	171
	172	if (irq < 0)
	173	return irq;
	174
	175	i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
	176
	177	ret = gpiod_direction_input(priv->scl);
	178	if (ret)
	179	goto unlock;
	180
	181	reinit_completion(&priv->scl_irq_completion);
	182
	183	ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
	184	"i2c_gpio_fault_injector_scl_irq", priv);
	185	if (ret)
	186	goto output;
	187
	188	wait_for_completion_interruptible(&priv->scl_irq_completion);
	189
	190	free_irq(irq, priv);
	191	output:
	192	ret = gpiod_direction_output(priv->scl, 1) ?: ret;
	193	unlock:
	194	i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
	195
	196	return ret;
	197	}
	198
	199	static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
	200	{
	201	struct i2c_gpio_private_data *priv = dev_id;
	202
	203	setsda(&priv->bit_data, 0);
	204	udelay(priv->scl_irq_data);
	205	setsda(&priv->bit_data, 1);
	206
	207	complete(&priv->scl_irq_completion);
	208
	209	return IRQ_HANDLED;
	210	}
	211
	212	static int fops_lose_arbitration_set(void *data, u64 duration)
	213	{
	214	struct i2c_gpio_private_data *priv = data;
	215
	216	if (duration > 100 * 1000)
	217	return -EINVAL;
	218
	219	priv->scl_irq_data = duration;
	220	/*
	221	* Interrupt on falling SCL. This ensures that the master under test has
	222	* really started the transfer. Interrupt on falling SDA did only
	223	* exercise 'bus busy' detection on some HW but not 'arbitration lost'.
	224	* Note that the interrupt latency may cause the first bits to be
	225	* transmitted correctly.
	226	*/
	227	return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
	228	}
	229	DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");
	230
bb6bdd51 WS	231	static irqreturn_t inject_panic_irq(int irq, void *dev_id)
	232	{
	233	struct i2c_gpio_private_data *priv = dev_id;
	234
	235	udelay(priv->scl_irq_data);
	236	panic("I2C fault injector induced panic");
	237
	238	return IRQ_HANDLED;
	239	}
	240
	241	static int fops_inject_panic_set(void *data, u64 duration)
	242	{
	243	struct i2c_gpio_private_data *priv = data;
	244
	245	if (duration > 100 * 1000)
	246	return -EINVAL;
	247
	248	priv->scl_irq_data = duration;
	249	/*
	250	* Interrupt on falling SCL. This ensures that the master under test has
	251	* really started the transfer.
	252	*/
	253	return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
	254	}
	255	DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");
	256
14911c6f WS	257	static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
	258	{
	259	struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
	260
	261	/*
	262	* If there will be a debugfs-dir per i2c adapter somewhen, put the
	263	* 'fault-injector' dir there. Until then, we have a global dir with
	264	* all adapters as subdirs.
	265	*/
24051338	266	if (!i2c_gpio_debug_dir)
14911c6f	267	i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
14911c6f WS	268
14911c6f WS	269	priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
14911c6f	270
63e57b6f WS	271	init_completion(&priv->scl_irq_completion);
63e57b6f WS	272
16d55daa WS	273	debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
16d55daa WS	274	priv, &fops_incomplete_addr_phase);
bbe89970 WS	275	debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
bbe89970 WS	276	priv, &fops_incomplete_write_byte);
bb6bdd51 WS	277	if (priv->bit_data.getscl) {
	278	debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir,
	279	priv, &fops_inject_panic);
63e57b6f WS	280	debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir,
63e57b6f WS	281	priv, &fops_lose_arbitration);
bb6bdd51	282	}
c6324fad WS	283	debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
c6324fad WS	284	debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
14911c6f WS	285	}
	286
	287	static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
	288	{
	289	struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
	290
	291	debugfs_remove_recursive(priv->debug_dir);
	292	}
	293	#else
	294	static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
	295	static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
	296	#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
	297
7b6e9dc7 BZ	298	/* Get i2c-gpio properties from DT or ACPI table */
	299	static void i2c_gpio_get_properties(struct device *dev,
	300	struct i2c_gpio_platform_data *pdata)
1b295c83 JD	301	{
	302	u32 reg;
	303
7b6e9dc7	304	device_property_read_u32(dev, "i2c-gpio,delay-us", &pdata->udelay);
8ffaa0f4	305
7b6e9dc7	306	if (!device_property_read_u32(dev, "i2c-gpio,timeout-ms", &reg))
8ffaa0f4 JCPV	307	pdata->timeout = msecs_to_jiffies(reg);
	308
	309	pdata->sda_is_open_drain =
7b6e9dc7	310	device_property_read_bool(dev, "i2c-gpio,sda-open-drain");
8ffaa0f4	311	pdata->scl_is_open_drain =
7b6e9dc7	312	device_property_read_bool(dev, "i2c-gpio,scl-open-drain");
8ffaa0f4	313	pdata->scl_is_output_only =
7b6e9dc7	314	device_property_read_bool(dev, "i2c-gpio,scl-output-only");
8786b095 HK	315	pdata->sda_is_output_only =
	316	device_property_read_bool(dev, "i2c-gpio,sda-output-only");
	317	pdata->sda_has_no_pullup =
	318	device_property_read_bool(dev, "i2c-gpio,sda-has-no-pullup");
	319	pdata->scl_has_no_pullup =
	320	device_property_read_bool(dev, "i2c-gpio,scl-has-no-pullup");
8ffaa0f4 JCPV	321	}
8ffaa0f4 JCPV	322
05c74778 LW	323	static struct gpio_desc i2c_gpio_get_desc(struct device dev,
	324	const char *con_id,
	325	unsigned int index,
	326	enum gpiod_flags gflags)
	327	{
	328	struct gpio_desc *retdesc;
	329	int ret;
	330
	331	retdesc = devm_gpiod_get(dev, con_id, gflags);
	332	if (!IS_ERR(retdesc)) {
	333	dev_dbg(dev, "got GPIO from name %s\n", con_id);
	334	return retdesc;
	335	}
	336
	337	retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
	338	if (!IS_ERR(retdesc)) {
	339	dev_dbg(dev, "got GPIO from index %u\n", index);
	340	return retdesc;
	341	}
	342
	343	ret = PTR_ERR(retdesc);
	344
	345	/* FIXME: hack in the old code, is this really necessary? */
	346	if (ret == -EINVAL)
	347	retdesc = ERR_PTR(-EPROBE_DEFER);
	348
	349	/* This happens if the GPIO driver is not yet probed, let's defer */
	350	if (ret == -ENOENT)
	351	retdesc = ERR_PTR(-EPROBE_DEFER);
	352
3747cd2e	353	if (PTR_ERR(retdesc) != -EPROBE_DEFER)
05c74778 LW	354	dev_err(dev, "error trying to get descriptor: %d\n", ret);
	355
	356	return retdesc;
	357	}
	358
0b255e92	359	static int i2c_gpio_probe(struct platform_device *pdev)
1c23af90	360	{
8ffaa0f4	361	struct i2c_gpio_private_data *priv;
1c23af90 HS	362	struct i2c_gpio_platform_data *pdata;
	363	struct i2c_algo_bit_data *bit_data;
	364	struct i2c_adapter *adap;
b9ab0517	365	struct device *dev = &pdev->dev;
7b6e9dc7	366	struct fwnode_handle *fwnode = dev_fwnode(dev);
7bb75029	367	enum gpiod_flags gflags;
1c23af90 HS	368	int ret;
1c23af90 HS	369
b9ab0517	370	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
b2e63555 LW	371	if (!priv)
b2e63555 LW	372	return -ENOMEM;
1c23af90	373
1b295c83 JD	374	adap = &priv->adap;
	375	bit_data = &priv->bit_data;
	376	pdata = &priv->pdata;
	377
7b6e9dc7 BZ	378	if (fwnode) {
7b6e9dc7 BZ	379	i2c_gpio_get_properties(dev, pdata);
1b295c83	380	} else {
b2e63555 LW	381	/*
	382	* If all platform data settings are zero it is OK
	383	* to not provide any platform data from the board.
	384	*/
b9ab0517 LW	385	if (dev_get_platdata(dev))
b9ab0517 LW	386	memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
1b295c83	387	}
1c23af90	388
b2e63555	389	/*
7bb75029	390	* First get the GPIO pins; if it fails, we'll defer the probe.
60c1d560 WS	391	* If the SCL/SDA lines are marked "open drain" by platform data or
	392	* device tree then this means that something outside of our control is
	393	* marking these lines to be handled as open drain, and we should just
	394	* handle them as we handle any other output. Else we enforce open
	395	* drain as this is required for an I2C bus.
b2e63555	396	*/
8786b095	397	if (pdata->sda_is_open_drain \|\| pdata->sda_has_no_pullup)
7bb75029 LW	398	gflags = GPIOD_OUT_HIGH;
	399	else
	400	gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
05c74778 LW	401	priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
	402	if (IS_ERR(priv->sda))
	403	return PTR_ERR(priv->sda);
	404
8786b095	405	if (pdata->scl_is_open_drain \|\| pdata->scl_has_no_pullup)
12b731dd	406	gflags = GPIOD_OUT_HIGH;
7bb75029	407	else
12b731dd	408	gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
05c74778 LW	409	priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
	410	if (IS_ERR(priv->scl))
	411	return PTR_ERR(priv->scl);
1c23af90	412
f11a0446 JK	413	if (gpiod_cansleep(priv->sda) \|\| gpiod_cansleep(priv->scl))
f11a0446 JK	414	dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
e155e388 WS	415	else
e155e388 WS	416	bit_data->can_do_atomic = true;
f11a0446	417
7bb75029 LW	418	bit_data->setsda = i2c_gpio_setsda_val;
	419	bit_data->setscl = i2c_gpio_setscl_val;
	420
1c23af90 HS	421	if (!pdata->scl_is_output_only)
1c23af90 HS	422	bit_data->getscl = i2c_gpio_getscl;
8786b095 HK	423	if (!pdata->sda_is_output_only)
8786b095 HK	424	bit_data->getsda = i2c_gpio_getsda;
1c23af90 HS	425
	426	if (pdata->udelay)
	427	bit_data->udelay = pdata->udelay;
	428	else if (pdata->scl_is_output_only)
	429	bit_data->udelay = 50; /* 10 kHz */
	430	else
	431	bit_data->udelay = 5; /* 100 kHz */
	432
	433	if (pdata->timeout)
	434	bit_data->timeout = pdata->timeout;
	435	else
	436	bit_data->timeout = HZ / 10; /* 100 ms */
	437
b2e63555	438	bit_data->data = priv;
1c23af90 HS	439
1c23af90 HS	440	adap->owner = THIS_MODULE;
7b6e9dc7	441	if (fwnode)
ea1558ce	442	strscpy(adap->name, dev_name(dev), sizeof(adap->name));
58a7371a BS	443	else
	444	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
	445
1c23af90	446	adap->algo_data = bit_data;
9fd12f38	447	adap->class = I2C_CLASS_HWMON;
b9ab0517	448	adap->dev.parent = dev;
7b6e9dc7	449	device_set_node(&adap->dev, fwnode);
1c23af90	450
44454baa	451	adap->nr = pdev->id;
7e69c3ac	452	ret = i2c_bit_add_numbered_bus(adap);
1c23af90	453	if (ret)
a0682a31	454	return ret;
1c23af90	455
8ffaa0f4	456	platform_set_drvdata(pdev, priv);
1c23af90	457
b2e63555 LW	458	/*
	459	* FIXME: using global GPIO numbers is not helpful. If/when we
	460	* get accessors to get the actual name of the GPIO line,
	461	* from the descriptor, then provide that instead.
	462	*/
b9ab0517	463	dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
b2e63555	464	desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
1c23af90 HS	465	pdata->scl_is_output_only
	466	? ", no clock stretching" : "");
	467
14911c6f WS	468	i2c_gpio_fault_injector_init(pdev);
14911c6f WS	469
1c23af90	470	return 0;
1c23af90 HS	471	}
1c23af90 HS	472
e190a0c3	473	static void i2c_gpio_remove(struct platform_device *pdev)
1c23af90	474	{
8ffaa0f4	475	struct i2c_gpio_private_data *priv;
1c23af90 HS	476	struct i2c_adapter *adap;
1c23af90 HS	477
14911c6f WS	478	i2c_gpio_fault_injector_exit(pdev);
14911c6f WS	479
8ffaa0f4 JCPV	480	priv = platform_get_drvdata(pdev);
8ffaa0f4 JCPV	481	adap = &priv->adap;
1c23af90 HS	482
1c23af90 HS	483	i2c_del_adapter(adap);
1c23af90 HS	484	}
1c23af90 HS	485
8ffaa0f4 JCPV	486	static const struct of_device_id i2c_gpio_dt_ids[] = {
	487	{ .compatible = "i2c-gpio", },
	488	{ /* sentinel */ }
	489	};
	490
	491	MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
8ffaa0f4	492
7b6e9dc7 BZ	493	static const struct acpi_device_id i2c_gpio_acpi_match[] = {
	494	{ "LOON0005" }, /* LoongArch */
	495	{ }
	496	};
	497	MODULE_DEVICE_TABLE(acpi, i2c_gpio_acpi_match);
	498
1c23af90 HS	499	static struct platform_driver i2c_gpio_driver = {
	500	.driver = {
	501	.name = "i2c-gpio",
73e9841b	502	.of_match_table = i2c_gpio_dt_ids,
7b6e9dc7	503	.acpi_match_table = i2c_gpio_acpi_match,
1c23af90	504	},
1efe7c55	505	.probe = i2c_gpio_probe,
e190a0c3	506	.remove_new = i2c_gpio_remove,
1c23af90 HS	507	};
	508
	509	static int __init i2c_gpio_init(void)
	510	{
	511	int ret;
	512
1efe7c55	513	ret = platform_driver_register(&i2c_gpio_driver);
1c23af90 HS	514	if (ret)
	515	printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
	516
	517	return ret;
	518	}
b8680784	519	subsys_initcall(i2c_gpio_init);
1c23af90 HS	520
	521	static void __exit i2c_gpio_exit(void)
	522	{
	523	platform_driver_unregister(&i2c_gpio_driver);
	524	}
	525	module_exit(i2c_gpio_exit);
	526
e05503ef	527	MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
1c23af90	528	MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
61adf63a	529	MODULE_LICENSE("GPL v2");
add8eda7	530	MODULE_ALIAS("platform:i2c-gpio");