drivers/w1/slaves/w1_ds28e17.c - linux/kernel/git/bpf/bpf - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  *	w1_ds28e17.c - w1 family 19 (DS28E17) driver
  *
  * Copyright (c) 2016 Jan Kandziora <jjj@gmx.de>
  */

 #include <linux/crc16.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/i2c.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>

 #define CRC16_INIT 0

 #include <linux/w1.h>

 #define W1_FAMILY_DS28E17 0x19

 /* Module setup. */
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Jan Kandziora <jjj@gmx.de>");
 MODULE_DESCRIPTION("w1 family 19 driver for DS28E17, 1-wire to I2C master bridge");
 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E17));


 /* Default I2C speed to be set when a DS28E17 is detected. */
 static int i2c_speed = 100;
 module_param_named(speed, i2c_speed, int, (S_IRUSR | S_IWUSR));
 MODULE_PARM_DESC(speed, "Default I2C speed to be set when a DS28E17 is detected");

 /* Default I2C stretch value to be set when a DS28E17 is detected. */
 static char i2c_stretch = 1;
 module_param_named(stretch, i2c_stretch, byte, (S_IRUSR | S_IWUSR));
 MODULE_PARM_DESC(stretch, "Default I2C stretch value to be set when a DS28E17 is detected");

 /* DS28E17 device command codes. */
 #define W1_F19_WRITE_DATA_WITH_STOP      0x4B
 #define W1_F19_WRITE_DATA_NO_STOP        0x5A
 #define W1_F19_WRITE_DATA_ONLY           0x69
 #define W1_F19_WRITE_DATA_ONLY_WITH_STOP 0x78
 #define W1_F19_READ_DATA_WITH_STOP       0x87
 #define W1_F19_WRITE_READ_DATA_WITH_STOP 0x2D
 #define W1_F19_WRITE_CONFIGURATION       0xD2
 #define W1_F19_READ_CONFIGURATION        0xE1
 #define W1_F19_ENABLE_SLEEP_MODE         0x1E
 #define W1_F19_READ_DEVICE_REVISION      0xC4

 /* DS28E17 status bits */
 #define W1_F19_STATUS_CRC     0x01
 #define W1_F19_STATUS_ADDRESS 0x02
 #define W1_F19_STATUS_START   0x08

 /*
  * Maximum number of I2C bytes to transfer within one CRC16 protected onewire
  * command.
  * */
 #define W1_F19_WRITE_DATA_LIMIT 255

 /* Maximum number of I2C bytes to read with one onewire command. */
 #define W1_F19_READ_DATA_LIMIT 255

 /* Constants for calculating the busy sleep. */
 #define W1_F19_BUSY_TIMEBASES { 90, 23, 10 }
 #define W1_F19_BUSY_GRATUITY  1000

 /* Number of checks for the busy flag before timeout. */
 #define W1_F19_BUSY_CHECKS 1000


 /* Slave specific data. */
 struct w1_f19_data {
 	u8 speed;
 	u8 stretch;
 	struct i2c_adapter adapter;
 };


 /* Wait a while until the busy flag clears. */
 static int w1_f19_i2c_busy_wait(struct w1_slave *sl, size_t count)
 {
 	const unsigned long timebases[3] = W1_F19_BUSY_TIMEBASES;
 	struct w1_f19_data *data = sl->family_data;
 	unsigned int checks;

 	/* Check the busy flag first in any case.*/
 	if (w1_touch_bit(sl->master, 1) == 0)
 		return 0;

 	/*
 	 * Do a generously long sleep in the beginning,
 	 * as we have to wait at least this time for all
 	 * the I2C bytes at the given speed to be transferred.
 	 */
 	usleep_range(timebases[data->speed] * (data->stretch) * count,
 		timebases[data->speed] * (data->stretch) * count
 		+ W1_F19_BUSY_GRATUITY);

 	/* Now continusly check the busy flag sent by the DS28E17. */
 	checks = W1_F19_BUSY_CHECKS;
 	while ((checks--) > 0) {
 		/* Return success if the busy flag is cleared. */
 		if (w1_touch_bit(sl->master, 1) == 0)
 			return 0;

 		/* Wait one non-streched byte timeslot. */
 		udelay(timebases[data->speed]);
 	}

 	/* Timeout. */
 	dev_warn(&sl->dev, "busy timeout\n");
 	return -ETIMEDOUT;
 }


 /* Utility function: result. */
 static size_t w1_f19_error(struct w1_slave *sl, u8 w1_buf[])
 {
 	/* Warnings. */
 	if (w1_buf[0] & W1_F19_STATUS_CRC)
 		dev_warn(&sl->dev, "crc16 mismatch\n");
 	if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
 		dev_warn(&sl->dev, "i2c device not responding\n");
 	if ((w1_buf[0] & (W1_F19_STATUS_CRC | W1_F19_STATUS_ADDRESS)) == 0
 			&& w1_buf[1] != 0) {
 		dev_warn(&sl->dev, "i2c short write, %d bytes not acknowledged\n",
 			w1_buf[1]);
 	}

 	/* Check error conditions. */
 	if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
 		return -ENXIO;
 	if (w1_buf[0] & W1_F19_STATUS_START)
 		return -EAGAIN;
 	if (w1_buf[0] != 0 || w1_buf[1] != 0)
 		return -EIO;

 	/* All ok. */
 	return 0;
 }


 /* Utility function: write data to I2C slave, single chunk. */
 static int __w1_f19_i2c_write(struct w1_slave *sl,
 	const u8 *command, size_t command_count,
 	const u8 *buffer, size_t count)
 {
 	u16 crc;
 	int error;
 	u8 w1_buf[2];

 	/* Send command and I2C data to DS28E17. */
 	crc = crc16(CRC16_INIT, command, command_count);
 	w1_write_block(sl->master, command, command_count);

 	w1_buf[0] = count;
 	crc = crc16(crc, w1_buf, 1);
 	w1_write_8(sl->master, w1_buf[0]);

 	crc = crc16(crc, buffer, count);
 	w1_write_block(sl->master, buffer, count);

 	w1_buf[0] = ~(crc & 0xFF);
 	w1_buf[1] = ~((crc >> 8) & 0xFF);
 	w1_write_block(sl->master, w1_buf, 2);

 	/* Wait until busy flag clears (or timeout). */
 	if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
 		return -ETIMEDOUT;

 	/* Read status from DS28E17. */
 	w1_read_block(sl->master, w1_buf, 2);

 	/* Check error conditions. */
 	error = w1_f19_error(sl, w1_buf);
 	if (error < 0)
 		return error;

 	/* Return number of bytes written. */
 	return count;
 }


 /* Write data to I2C slave. */
 static int w1_f19_i2c_write(struct w1_slave *sl, u16 i2c_address,
 	const u8 *buffer, size_t count, bool stop)
 {
 	int result;
 	int remaining = count;
 	const u8 *p;
 	u8 command[2];

 	/* Check input. */
 	if (count == 0)
 		return -EOPNOTSUPP;

 	/* Check whether we need multiple commands. */
 	if (count <= W1_F19_WRITE_DATA_LIMIT) {
 		/*
 		 * Small data amount. Data can be sent with
 		 * a single onewire command.
 		 */

 		/* Send all data to DS28E17. */
 		command[0] = (stop ? W1_F19_WRITE_DATA_WITH_STOP
 			: W1_F19_WRITE_DATA_NO_STOP);
 		command[1] = i2c_address << 1;
 		result = __w1_f19_i2c_write(sl, command, 2, buffer, count);
 	} else {
 		/* Large data amount. Data has to be sent in multiple chunks. */

 		/* Send first chunk to DS28E17. */
 		p = buffer;
 		command[0] = W1_F19_WRITE_DATA_NO_STOP;
 		command[1] = i2c_address << 1;
 		result = __w1_f19_i2c_write(sl, command, 2, p,
 			W1_F19_WRITE_DATA_LIMIT);
 		if (result < 0)
 			return result;

 		/* Resume to same DS28E17. */
 		if (w1_reset_resume_command(sl->master))
 			return -EIO;

 		/* Next data chunk. */
 		p += W1_F19_WRITE_DATA_LIMIT;
 		remaining -= W1_F19_WRITE_DATA_LIMIT;

 		while (remaining > W1_F19_WRITE_DATA_LIMIT) {
 			/* Send intermediate chunk to DS28E17. */
 			command[0] = W1_F19_WRITE_DATA_ONLY;
 			result = __w1_f19_i2c_write(sl, command, 1, p,
 					W1_F19_WRITE_DATA_LIMIT);
 			if (result < 0)
 				return result;

 			/* Resume to same DS28E17. */
 			if (w1_reset_resume_command(sl->master))
 				return -EIO;

 			/* Next data chunk. */
 			p += W1_F19_WRITE_DATA_LIMIT;
 			remaining -= W1_F19_WRITE_DATA_LIMIT;
 		}

 		/* Send final chunk to DS28E17. */
 		command[0] = (stop ? W1_F19_WRITE_DATA_ONLY_WITH_STOP
 			: W1_F19_WRITE_DATA_ONLY);
 		result = __w1_f19_i2c_write(sl, command, 1, p, remaining);
 	}

 	return result;
 }


 /* Read data from I2C slave. */
 static int w1_f19_i2c_read(struct w1_slave *sl, u16 i2c_address,
 	u8 *buffer, size_t count)
 {
 	u16 crc;
 	int error;
 	u8 w1_buf[5];

 	/* Check input. */
 	if (count == 0)
 		return -EOPNOTSUPP;

 	/* Send command to DS28E17. */
 	w1_buf[0] = W1_F19_READ_DATA_WITH_STOP;
 	w1_buf[1] = i2c_address << 1 | 0x01;
 	w1_buf[2] = count;
 	crc = crc16(CRC16_INIT, w1_buf, 3);
 	w1_buf[3] = ~(crc & 0xFF);
 	w1_buf[4] = ~((crc >> 8) & 0xFF);
 	w1_write_block(sl->master, w1_buf, 5);

 	/* Wait until busy flag clears (or timeout). */
 	if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
 		return -ETIMEDOUT;

 	/* Read status from DS28E17. */
 	w1_buf[0] = w1_read_8(sl->master);
 	w1_buf[1] = 0;

 	/* Check error conditions. */
 	error = w1_f19_error(sl, w1_buf);
 	if (error < 0)
 		return error;

 	/* Read received I2C data from DS28E17. */
 	return w1_read_block(sl->master, buffer, count);
 }


 /* Write to, then read data from I2C slave. */
 static int w1_f19_i2c_write_read(struct w1_slave *sl, u16 i2c_address,
 	const u8 *wbuffer, size_t wcount, u8 *rbuffer, size_t rcount)
 {
 	u16 crc;
 	int error;
 	u8 w1_buf[3];

 	/* Check input. */
 	if (wcount == 0 || rcount == 0)
 		return -EOPNOTSUPP;

 	/* Send command and I2C data to DS28E17. */
 	w1_buf[0] = W1_F19_WRITE_READ_DATA_WITH_STOP;
 	w1_buf[1] = i2c_address << 1;
 	w1_buf[2] = wcount;
 	crc = crc16(CRC16_INIT, w1_buf, 3);
 	w1_write_block(sl->master, w1_buf, 3);

 	crc = crc16(crc, wbuffer, wcount);
 	w1_write_block(sl->master, wbuffer, wcount);

 	w1_buf[0] = rcount;
 	crc = crc16(crc, w1_buf, 1);
 	w1_buf[1] = ~(crc & 0xFF);
 	w1_buf[2] = ~((crc >> 8) & 0xFF);
 	w1_write_block(sl->master, w1_buf, 3);

 	/* Wait until busy flag clears (or timeout). */
 	if (w1_f19_i2c_busy_wait(sl, wcount + rcount + 2) < 0)
 		return -ETIMEDOUT;

 	/* Read status from DS28E17. */
 	w1_read_block(sl->master, w1_buf, 2);

 	/* Check error conditions. */
 	error = w1_f19_error(sl, w1_buf);
 	if (error < 0)
 		return error;

 	/* Read received I2C data from DS28E17. */
 	return w1_read_block(sl->master, rbuffer, rcount);
 }


 /* Do an I2C master transfer. */
 static int w1_f19_i2c_master_transfer(struct i2c_adapter *adapter,
 	struct i2c_msg *msgs, int num)
 {
 	struct w1_slave *sl = (struct w1_slave *) adapter->algo_data;
 	int i = 0;
 	int result = 0;

 	/* Start onewire transaction. */
 	mutex_lock(&sl->master->bus_mutex);

 	/* Select DS28E17. */
 	if (w1_reset_select_slave(sl)) {
 		i = -EIO;
 		goto error;
 	}

 	/* Loop while there are still messages to transfer. */
 	while (i < num) {
 		/*
 		 * Check for special case: Small write followed
 		 * by read to same I2C device.
 		 */
 		if (i < (num-1)
 			&& msgs[i].addr == msgs[i+1].addr
 			&& !(msgs[i].flags & I2C_M_RD)
 			&& (msgs[i+1].flags & I2C_M_RD)
 			&& (msgs[i].len <= W1_F19_WRITE_DATA_LIMIT)) {
 			/*
 			 * The DS28E17 has a combined transfer
 			 * for small write+read.
 			 */
 			result = w1_f19_i2c_write_read(sl, msgs[i].addr,
 				msgs[i].buf, msgs[i].len,
 				msgs[i+1].buf, msgs[i+1].len);
 			if (result < 0) {
 				i = result;
 				goto error;
 			}

 			/*
 			 * Check if we should interpret the read data
 			 * as a length byte. The DS28E17 unfortunately
 			 * has no read without stop, so we can just do
 			 * another simple read in that case.
 			 */
 			if (msgs[i+1].flags & I2C_M_RECV_LEN) {
 				result = w1_f19_i2c_read(sl, msgs[i+1].addr,
 					&(msgs[i+1].buf[1]), msgs[i+1].buf[0]);
 				if (result < 0) {
 					i = result;
 					goto error;
 				}
 			}

 			/* Eat up read message, too. */
 			i++;
 		} else if (msgs[i].flags & I2C_M_RD) {
 			/* Read transfer. */
 			result = w1_f19_i2c_read(sl, msgs[i].addr,
 				msgs[i].buf, msgs[i].len);
 			if (result < 0) {
 				i = result;
 				goto error;
 			}

 			/*
 			 * Check if we should interpret the read data
 			 * as a length byte. The DS28E17 unfortunately
 			 * has no read without stop, so we can just do
 			 * another simple read in that case.
 			 */
 			if (msgs[i].flags & I2C_M_RECV_LEN) {
 				result = w1_f19_i2c_read(sl,
 					msgs[i].addr,
 					&(msgs[i].buf[1]),
 					msgs[i].buf[0]);
 				if (result < 0) {
 					i = result;
 					goto error;
 				}
 			}
 		} else {
 			/*
 			 * Write transfer.
 			 * Stop condition only for last
 			 * transfer.
 			 */
 			result = w1_f19_i2c_write(sl,
 				msgs[i].addr,
 				msgs[i].buf,
 				msgs[i].len,
 				i == (num-1));
 			if (result < 0) {
 				i = result;
 				goto error;
 			}
 		}

 		/* Next message. */
 		i++;

 		/* Are there still messages to send/receive? */
 		if (i < num) {
 			/* Yes. Resume to same DS28E17. */
 			if (w1_reset_resume_command(sl->master)) {
 				i = -EIO;
 				goto error;
 			}
 		}
 	}

 error:
 	/* End onewire transaction. */
 	mutex_unlock(&sl->master->bus_mutex);

 	/* Return number of messages processed or error. */
 	return i;
 }


 /* Get I2C adapter functionality. */
 static u32 w1_f19_i2c_functionality(struct i2c_adapter *adapter)
 {
 	/*
 	 * Plain I2C functions only.
 	 * SMBus is emulated by the kernel's I2C layer.
 	 * No "I2C_FUNC_SMBUS_QUICK"
 	 * No "I2C_FUNC_SMBUS_READ_BLOCK_DATA"
 	 * No "I2C_FUNC_SMBUS_BLOCK_PROC_CALL"
 	 */
 	return I2C_FUNC_I2C |
 		I2C_FUNC_SMBUS_BYTE |
 		I2C_FUNC_SMBUS_BYTE_DATA |
 		I2C_FUNC_SMBUS_WORD_DATA |
 		I2C_FUNC_SMBUS_PROC_CALL |
 		I2C_FUNC_SMBUS_WRITE_BLOCK_DATA |
 		I2C_FUNC_SMBUS_I2C_BLOCK |
 		I2C_FUNC_SMBUS_PEC;
 }


 /* I2C adapter quirks. */
 static const struct i2c_adapter_quirks w1_f19_i2c_adapter_quirks = {
 	.max_read_len = W1_F19_READ_DATA_LIMIT,
 };

 /* I2C algorithm. */
 static const struct i2c_algorithm w1_f19_i2c_algorithm = {
 	.master_xfer    = w1_f19_i2c_master_transfer,
 	.functionality  = w1_f19_i2c_functionality,
 };


 /* Read I2C speed from DS28E17. */
 static int w1_f19_get_i2c_speed(struct w1_slave *sl)
 {
 	struct w1_f19_data *data = sl->family_data;
 	int result = -EIO;

 	/* Start onewire transaction. */
 	mutex_lock(&sl->master->bus_mutex);

 	/* Select slave. */
 	if (w1_reset_select_slave(sl))
 		goto error;

 	/* Read slave configuration byte. */
 	w1_write_8(sl->master, W1_F19_READ_CONFIGURATION);
 	result = w1_read_8(sl->master);
 	if (result < 0 || result > 2) {
 		result = -EIO;
 		goto error;
 	}

 	/* Update speed in slave specific data. */
 	data->speed = result;

 error:
 	/* End onewire transaction. */
 	mutex_unlock(&sl->master->bus_mutex);

 	return result;
 }


 /* Set I2C speed on DS28E17. */
 static int __w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
 {
 	struct w1_f19_data *data = sl->family_data;
 	const int i2c_speeds[3] = { 100, 400, 900 };
 	u8 w1_buf[2];

 	/* Select slave. */
 	if (w1_reset_select_slave(sl))
 		return -EIO;

 	w1_buf[0] = W1_F19_WRITE_CONFIGURATION;
 	w1_buf[1] = speed;
 	w1_write_block(sl->master, w1_buf, 2);

 	/* Update speed in slave specific data. */
 	data->speed = speed;

 	dev_info(&sl->dev, "i2c speed set to %d kBaud\n", i2c_speeds[speed]);

 	return 0;
 }

 static int w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
 {
 	int result;

 	/* Start onewire transaction. */
 	mutex_lock(&sl->master->bus_mutex);

 	/* Set I2C speed on DS28E17. */
 	result = __w1_f19_set_i2c_speed(sl, speed);

 	/* End onewire transaction. */
 	mutex_unlock(&sl->master->bus_mutex);

 	return result;
 }


 /* Sysfs attributes. */

 /* I2C speed attribute for a single chip. */
 static ssize_t speed_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
 	struct w1_slave *sl = dev_to_w1_slave(dev);
 	int result;

 	/* Read current speed from slave. Updates data->speed. */
 	result = w1_f19_get_i2c_speed(sl);
 	if (result < 0)
 		return result;

 	/* Return current speed value. */
 	return sprintf(buf, "%d\n", result);
 }

 static ssize_t speed_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t count)
 {
 	struct w1_slave *sl = dev_to_w1_slave(dev);
 	int error;

 	/* Valid values are: "100", "400", "900" */
 	if (count < 3 || count > 4 || !buf)
 		return -EINVAL;
 	if (count == 4 && buf[3] != '\n')
 		return -EINVAL;
 	if (buf[1] != '0' || buf[2] != '0')
 		return -EINVAL;

 	/* Set speed on slave. */
 	switch (buf[0]) {
 	case '1':
 		error = w1_f19_set_i2c_speed(sl, 0);
 		break;
 	case '4':
 		error = w1_f19_set_i2c_speed(sl, 1);
 		break;
 	case '9':
 		error = w1_f19_set_i2c_speed(sl, 2);
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (error < 0)
 		return error;

 	/* Return bytes written. */
 	return count;
 }

 static DEVICE_ATTR_RW(speed);


 /* Busy stretch attribute for a single chip. */
 static ssize_t stretch_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
 	struct w1_slave *sl = dev_to_w1_slave(dev);
 	struct w1_f19_data *data = sl->family_data;

 	/* Return current stretch value. */
 	return sprintf(buf, "%d\n", data->stretch);
 }

 static ssize_t stretch_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t count)
 {
 	struct w1_slave *sl = dev_to_w1_slave(dev);
 	struct w1_f19_data *data = sl->family_data;

 	/* Valid values are '1' to '9' */
 	if (count < 1 || count > 2 || !buf)
 		return -EINVAL;
 	if (count == 2 && buf[1] != '\n')
 		return -EINVAL;
 	if (buf[0] < '1' || buf[0] > '9')
 		return -EINVAL;

 	/* Set busy stretch value. */
 	data->stretch = buf[0] & 0x0F;

 	/* Return bytes written. */
 	return count;
 }

 static DEVICE_ATTR_RW(stretch);


 /* All attributes. */
 static struct attribute *w1_f19_attrs[] = {
 	&dev_attr_speed.attr,
 	&dev_attr_stretch.attr,
 	NULL,
 };

 static const struct attribute_group w1_f19_group = {
 	.attrs		= w1_f19_attrs,
 };

 static const struct attribute_group *w1_f19_groups[] = {
 	&w1_f19_group,
 	NULL,
 };


 /* Slave add and remove functions. */
 static int w1_f19_add_slave(struct w1_slave *sl)
 {
 	struct w1_f19_data *data = NULL;

 	/* Allocate memory for slave specific data. */
 	data = devm_kzalloc(&sl->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 	sl->family_data = data;

 	/* Setup default I2C speed on slave. */
 	switch (i2c_speed) {
 	case 100:
 		__w1_f19_set_i2c_speed(sl, 0);
 		break;
 	case 400:
 		__w1_f19_set_i2c_speed(sl, 1);
 		break;
 	case 900:
 		__w1_f19_set_i2c_speed(sl, 2);
 		break;
 	default:
 		/*
 		 * A i2c_speed module parameter of anything else
 		 * than 100, 400, 900 means not to touch the
 		 * speed of the DS28E17.
 		 * We assume 400kBaud, the power-on value.
 		 */
 		data->speed = 1;
 	}

 	/*
 	 * Setup default busy stretch
 	 * configuration for the DS28E17.
 	 */
 	data->stretch = i2c_stretch;

 	/* Setup I2C adapter. */
 	data->adapter.owner      = THIS_MODULE;
 	data->adapter.algo       = &w1_f19_i2c_algorithm;
 	data->adapter.algo_data  = sl;
 	strcpy(data->adapter.name, "w1-");
 	strcat(data->adapter.name, sl->name);
 	data->adapter.dev.parent = &sl->dev;
 	data->adapter.quirks     = &w1_f19_i2c_adapter_quirks;

 	return i2c_add_adapter(&data->adapter);
 }

 static void w1_f19_remove_slave(struct w1_slave *sl)
 {
 	struct w1_f19_data *family_data = sl->family_data;

 	/* Delete I2C adapter. */
 	i2c_del_adapter(&family_data->adapter);

 	/* Free slave specific data. */
 	devm_kfree(&sl->dev, family_data);
 	sl->family_data = NULL;
 }


 /* Declarations within the w1 subsystem. */
 static struct w1_family_ops w1_f19_fops = {
 	.add_slave = w1_f19_add_slave,
 	.remove_slave = w1_f19_remove_slave,
 	.groups = w1_f19_groups,
 };

 static struct w1_family w1_family_19 = {
 	.fid = W1_FAMILY_DS28E17,
 	.fops = &w1_f19_fops,
 };


 /* Module init and remove functions. */
 static int __init w1_f19_init(void)
 {
 	return w1_register_family(&w1_family_19);
 }

 static void __exit w1_f19_fini(void)
 {
 	w1_unregister_family(&w1_family_19);
 }

 module_init(w1_f19_init);
 module_exit(w1_f19_fini);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* w1_ds28e17.c - w1 family 19 (DS28E17) driver
	*
	* Copyright (c) 2016 Jan Kandziora <jjj@gmx.de>
	*/

	#include <linux/crc16.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/i2c.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/slab.h>
	#include <linux/types.h>
	#include <linux/uaccess.h>

	#define CRC16_INIT 0

	#include <linux/w1.h>

	#define W1_FAMILY_DS28E17 0x19

	/* Module setup. */
	MODULE_LICENSE("GPL v2");
	MODULE_AUTHOR("Jan Kandziora <jjj@gmx.de>");
	MODULE_DESCRIPTION("w1 family 19 driver for DS28E17, 1-wire to I2C master bridge");
	MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E17));


	/* Default I2C speed to be set when a DS28E17 is detected. */
	static int i2c_speed = 100;
	module_param_named(speed, i2c_speed, int, (S_IRUSR \| S_IWUSR));
	MODULE_PARM_DESC(speed, "Default I2C speed to be set when a DS28E17 is detected");

	/* Default I2C stretch value to be set when a DS28E17 is detected. */
	static char i2c_stretch = 1;
	module_param_named(stretch, i2c_stretch, byte, (S_IRUSR \| S_IWUSR));
	MODULE_PARM_DESC(stretch, "Default I2C stretch value to be set when a DS28E17 is detected");

	/* DS28E17 device command codes. */
	#define W1_F19_WRITE_DATA_WITH_STOP 0x4B
	#define W1_F19_WRITE_DATA_NO_STOP 0x5A
	#define W1_F19_WRITE_DATA_ONLY 0x69
	#define W1_F19_WRITE_DATA_ONLY_WITH_STOP 0x78
	#define W1_F19_READ_DATA_WITH_STOP 0x87
	#define W1_F19_WRITE_READ_DATA_WITH_STOP 0x2D
	#define W1_F19_WRITE_CONFIGURATION 0xD2
	#define W1_F19_READ_CONFIGURATION 0xE1
	#define W1_F19_ENABLE_SLEEP_MODE 0x1E
	#define W1_F19_READ_DEVICE_REVISION 0xC4

	/* DS28E17 status bits */
	#define W1_F19_STATUS_CRC 0x01
	#define W1_F19_STATUS_ADDRESS 0x02
	#define W1_F19_STATUS_START 0x08

	/*
	* Maximum number of I2C bytes to transfer within one CRC16 protected onewire
	* command.
	* */
	#define W1_F19_WRITE_DATA_LIMIT 255

	/* Maximum number of I2C bytes to read with one onewire command. */
	#define W1_F19_READ_DATA_LIMIT 255

	/* Constants for calculating the busy sleep. */
	#define W1_F19_BUSY_TIMEBASES { 90, 23, 10 }
	#define W1_F19_BUSY_GRATUITY 1000

	/* Number of checks for the busy flag before timeout. */
	#define W1_F19_BUSY_CHECKS 1000


	/* Slave specific data. */
	struct w1_f19_data {
	u8 speed;
	u8 stretch;
	struct i2c_adapter adapter;
	};


	/* Wait a while until the busy flag clears. */
	static int w1_f19_i2c_busy_wait(struct w1_slave *sl, size_t count)
	{
	const unsigned long timebases[3] = W1_F19_BUSY_TIMEBASES;
	struct w1_f19_data *data = sl->family_data;
	unsigned int checks;

	/* Check the busy flag first in any case.*/
	if (w1_touch_bit(sl->master, 1) == 0)
	return 0;

	/*
	* Do a generously long sleep in the beginning,
	* as we have to wait at least this time for all
	* the I2C bytes at the given speed to be transferred.
	*/
	usleep_range(timebases[data->speed] * (data->stretch) * count,
	timebases[data->speed] * (data->stretch) * count
	+ W1_F19_BUSY_GRATUITY);

	/* Now continusly check the busy flag sent by the DS28E17. */
	checks = W1_F19_BUSY_CHECKS;
	while ((checks--) > 0) {
	/* Return success if the busy flag is cleared. */
	if (w1_touch_bit(sl->master, 1) == 0)
	return 0;

	/* Wait one non-streched byte timeslot. */
	udelay(timebases[data->speed]);
	}

	/* Timeout. */
	dev_warn(&sl->dev, "busy timeout\n");
	return -ETIMEDOUT;
	}


	/* Utility function: result. */
	static size_t w1_f19_error(struct w1_slave *sl, u8 w1_buf[])
	{
	/* Warnings. */
	if (w1_buf[0] & W1_F19_STATUS_CRC)
	dev_warn(&sl->dev, "crc16 mismatch\n");
	if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
	dev_warn(&sl->dev, "i2c device not responding\n");
	if ((w1_buf[0] & (W1_F19_STATUS_CRC \| W1_F19_STATUS_ADDRESS)) == 0
	&& w1_buf[1] != 0) {
	dev_warn(&sl->dev, "i2c short write, %d bytes not acknowledged\n",
	w1_buf[1]);
	}

	/* Check error conditions. */
	if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
	return -ENXIO;
	if (w1_buf[0] & W1_F19_STATUS_START)
	return -EAGAIN;
	if (w1_buf[0] != 0 \|\| w1_buf[1] != 0)
	return -EIO;

	/* All ok. */
	return 0;
	}


	/* Utility function: write data to I2C slave, single chunk. */
	static int __w1_f19_i2c_write(struct w1_slave *sl,
	const u8 *command, size_t command_count,
	const u8 *buffer, size_t count)
	{
	u16 crc;
	int error;
	u8 w1_buf[2];

	/* Send command and I2C data to DS28E17. */
	crc = crc16(CRC16_INIT, command, command_count);
	w1_write_block(sl->master, command, command_count);

	w1_buf[0] = count;
	crc = crc16(crc, w1_buf, 1);
	w1_write_8(sl->master, w1_buf[0]);

	crc = crc16(crc, buffer, count);
	w1_write_block(sl->master, buffer, count);

	w1_buf[0] = ~(crc & 0xFF);
	w1_buf[1] = ~((crc >> 8) & 0xFF);
	w1_write_block(sl->master, w1_buf, 2);

	/* Wait until busy flag clears (or timeout). */
	if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
	return -ETIMEDOUT;

	/* Read status from DS28E17. */
	w1_read_block(sl->master, w1_buf, 2);

	/* Check error conditions. */
	error = w1_f19_error(sl, w1_buf);
	if (error < 0)
	return error;

	/* Return number of bytes written. */
	return count;
	}


	/* Write data to I2C slave. */
	static int w1_f19_i2c_write(struct w1_slave *sl, u16 i2c_address,
	const u8 *buffer, size_t count, bool stop)
	{
	int result;
	int remaining = count;
	const u8 *p;
	u8 command[2];

	/* Check input. */
	if (count == 0)
	return -EOPNOTSUPP;

	/* Check whether we need multiple commands. */
	if (count <= W1_F19_WRITE_DATA_LIMIT) {
	/*
	* Small data amount. Data can be sent with
	* a single onewire command.
	*/

	/* Send all data to DS28E17. */
	command[0] = (stop ? W1_F19_WRITE_DATA_WITH_STOP
	: W1_F19_WRITE_DATA_NO_STOP);
	command[1] = i2c_address << 1;
	result = __w1_f19_i2c_write(sl, command, 2, buffer, count);
	} else {
	/* Large data amount. Data has to be sent in multiple chunks. */

	/* Send first chunk to DS28E17. */
	p = buffer;
	command[0] = W1_F19_WRITE_DATA_NO_STOP;
	command[1] = i2c_address << 1;
	result = __w1_f19_i2c_write(sl, command, 2, p,
	W1_F19_WRITE_DATA_LIMIT);
	if (result < 0)
	return result;

	/* Resume to same DS28E17. */
	if (w1_reset_resume_command(sl->master))
	return -EIO;

	/* Next data chunk. */
	p += W1_F19_WRITE_DATA_LIMIT;
	remaining -= W1_F19_WRITE_DATA_LIMIT;

	while (remaining > W1_F19_WRITE_DATA_LIMIT) {
	/* Send intermediate chunk to DS28E17. */
	command[0] = W1_F19_WRITE_DATA_ONLY;
	result = __w1_f19_i2c_write(sl, command, 1, p,
	W1_F19_WRITE_DATA_LIMIT);
	if (result < 0)
	return result;

	/* Resume to same DS28E17. */
	if (w1_reset_resume_command(sl->master))
	return -EIO;

	/* Next data chunk. */
	p += W1_F19_WRITE_DATA_LIMIT;
	remaining -= W1_F19_WRITE_DATA_LIMIT;
	}

	/* Send final chunk to DS28E17. */
	command[0] = (stop ? W1_F19_WRITE_DATA_ONLY_WITH_STOP
	: W1_F19_WRITE_DATA_ONLY);
	result = __w1_f19_i2c_write(sl, command, 1, p, remaining);
	}

	return result;
	}


	/* Read data from I2C slave. */
	static int w1_f19_i2c_read(struct w1_slave *sl, u16 i2c_address,
	u8 *buffer, size_t count)
	{
	u16 crc;
	int error;
	u8 w1_buf[5];

	/* Check input. */
	if (count == 0)
	return -EOPNOTSUPP;

	/* Send command to DS28E17. */
	w1_buf[0] = W1_F19_READ_DATA_WITH_STOP;
	w1_buf[1] = i2c_address << 1 \| 0x01;
	w1_buf[2] = count;
	crc = crc16(CRC16_INIT, w1_buf, 3);
	w1_buf[3] = ~(crc & 0xFF);
	w1_buf[4] = ~((crc >> 8) & 0xFF);
	w1_write_block(sl->master, w1_buf, 5);

	/* Wait until busy flag clears (or timeout). */
	if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
	return -ETIMEDOUT;

	/* Read status from DS28E17. */
	w1_buf[0] = w1_read_8(sl->master);
	w1_buf[1] = 0;

	/* Check error conditions. */
	error = w1_f19_error(sl, w1_buf);
	if (error < 0)
	return error;

	/* Read received I2C data from DS28E17. */
	return w1_read_block(sl->master, buffer, count);
	}


	/* Write to, then read data from I2C slave. */
	static int w1_f19_i2c_write_read(struct w1_slave *sl, u16 i2c_address,
	const u8 wbuffer, size_t wcount, u8 rbuffer, size_t rcount)
	{
	u16 crc;
	int error;
	u8 w1_buf[3];

	/* Check input. */
	if (wcount == 0 \|\| rcount == 0)
	return -EOPNOTSUPP;

	/* Send command and I2C data to DS28E17. */
	w1_buf[0] = W1_F19_WRITE_READ_DATA_WITH_STOP;
	w1_buf[1] = i2c_address << 1;
	w1_buf[2] = wcount;
	crc = crc16(CRC16_INIT, w1_buf, 3);
	w1_write_block(sl->master, w1_buf, 3);

	crc = crc16(crc, wbuffer, wcount);
	w1_write_block(sl->master, wbuffer, wcount);

	w1_buf[0] = rcount;
	crc = crc16(crc, w1_buf, 1);
	w1_buf[1] = ~(crc & 0xFF);
	w1_buf[2] = ~((crc >> 8) & 0xFF);
	w1_write_block(sl->master, w1_buf, 3);

	/* Wait until busy flag clears (or timeout). */
	if (w1_f19_i2c_busy_wait(sl, wcount + rcount + 2) < 0)
	return -ETIMEDOUT;

	/* Read status from DS28E17. */
	w1_read_block(sl->master, w1_buf, 2);

	/* Check error conditions. */
	error = w1_f19_error(sl, w1_buf);
	if (error < 0)
	return error;

	/* Read received I2C data from DS28E17. */
	return w1_read_block(sl->master, rbuffer, rcount);
	}


	/* Do an I2C master transfer. */
	static int w1_f19_i2c_master_transfer(struct i2c_adapter *adapter,
	struct i2c_msg *msgs, int num)
	{
	struct w1_slave sl = (struct w1_slave ) adapter->algo_data;
	int i = 0;
	int result = 0;

	/* Start onewire transaction. */
	mutex_lock(&sl->master->bus_mutex);

	/* Select DS28E17. */
	if (w1_reset_select_slave(sl)) {
	i = -EIO;
	goto error;
	}

	/* Loop while there are still messages to transfer. */
	while (i < num) {
	/*
	* Check for special case: Small write followed
	* by read to same I2C device.
	*/
	if (i < (num-1)
	&& msgs[i].addr == msgs[i+1].addr
	&& !(msgs[i].flags & I2C_M_RD)
	&& (msgs[i+1].flags & I2C_M_RD)
	&& (msgs[i].len <= W1_F19_WRITE_DATA_LIMIT)) {
	/*
	* The DS28E17 has a combined transfer
	* for small write+read.
	*/
	result = w1_f19_i2c_write_read(sl, msgs[i].addr,
	msgs[i].buf, msgs[i].len,
	msgs[i+1].buf, msgs[i+1].len);
	if (result < 0) {
	i = result;
	goto error;
	}

	/*
	* Check if we should interpret the read data
	* as a length byte. The DS28E17 unfortunately
	* has no read without stop, so we can just do
	* another simple read in that case.
	*/
	if (msgs[i+1].flags & I2C_M_RECV_LEN) {
	result = w1_f19_i2c_read(sl, msgs[i+1].addr,
	&(msgs[i+1].buf[1]), msgs[i+1].buf[0]);
	if (result < 0) {
	i = result;
	goto error;
	}
	}

	/* Eat up read message, too. */
	i++;
	} else if (msgs[i].flags & I2C_M_RD) {
	/* Read transfer. */
	result = w1_f19_i2c_read(sl, msgs[i].addr,
	msgs[i].buf, msgs[i].len);
	if (result < 0) {
	i = result;
	goto error;
	}

	/*
	* Check if we should interpret the read data
	* as a length byte. The DS28E17 unfortunately
	* has no read without stop, so we can just do
	* another simple read in that case.
	*/
	if (msgs[i].flags & I2C_M_RECV_LEN) {
	result = w1_f19_i2c_read(sl,
	msgs[i].addr,
	&(msgs[i].buf[1]),
	msgs[i].buf[0]);
	if (result < 0) {
	i = result;
	goto error;
	}
	}
	} else {
	/*
	* Write transfer.
	* Stop condition only for last
	* transfer.
	*/
	result = w1_f19_i2c_write(sl,
	msgs[i].addr,
	msgs[i].buf,
	msgs[i].len,
	i == (num-1));
	if (result < 0) {
	i = result;
	goto error;
	}
	}

	/* Next message. */
	i++;

	/* Are there still messages to send/receive? */
	if (i < num) {
	/* Yes. Resume to same DS28E17. */
	if (w1_reset_resume_command(sl->master)) {
	i = -EIO;
	goto error;
	}
	}
	}

	error:
	/* End onewire transaction. */
	mutex_unlock(&sl->master->bus_mutex);

	/* Return number of messages processed or error. */
	return i;
	}


	/* Get I2C adapter functionality. */
	static u32 w1_f19_i2c_functionality(struct i2c_adapter *adapter)
	{
	/*
	* Plain I2C functions only.
	* SMBus is emulated by the kernel's I2C layer.
	* No "I2C_FUNC_SMBUS_QUICK"
	* No "I2C_FUNC_SMBUS_READ_BLOCK_DATA"
	* No "I2C_FUNC_SMBUS_BLOCK_PROC_CALL"
	*/
	return I2C_FUNC_I2C \|
	I2C_FUNC_SMBUS_BYTE \|
	I2C_FUNC_SMBUS_BYTE_DATA \|
	I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_PROC_CALL \|
	I2C_FUNC_SMBUS_WRITE_BLOCK_DATA \|
	I2C_FUNC_SMBUS_I2C_BLOCK \|
	I2C_FUNC_SMBUS_PEC;
	}


	/* I2C adapter quirks. */
	static const struct i2c_adapter_quirks w1_f19_i2c_adapter_quirks = {
	.max_read_len = W1_F19_READ_DATA_LIMIT,
	};

	/* I2C algorithm. */
	static const struct i2c_algorithm w1_f19_i2c_algorithm = {
	.master_xfer = w1_f19_i2c_master_transfer,
	.functionality = w1_f19_i2c_functionality,
	};


	/* Read I2C speed from DS28E17. */
	static int w1_f19_get_i2c_speed(struct w1_slave *sl)
	{
	struct w1_f19_data *data = sl->family_data;
	int result = -EIO;

	/* Start onewire transaction. */
	mutex_lock(&sl->master->bus_mutex);

	/* Select slave. */
	if (w1_reset_select_slave(sl))
	goto error;

	/* Read slave configuration byte. */
	w1_write_8(sl->master, W1_F19_READ_CONFIGURATION);
	result = w1_read_8(sl->master);
	if (result < 0 \|\| result > 2) {
	result = -EIO;
	goto error;
	}

	/* Update speed in slave specific data. */
	data->speed = result;

	error:
	/* End onewire transaction. */
	mutex_unlock(&sl->master->bus_mutex);

	return result;
	}


	/* Set I2C speed on DS28E17. */
	static int __w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
	{
	struct w1_f19_data *data = sl->family_data;
	const int i2c_speeds[3] = { 100, 400, 900 };
	u8 w1_buf[2];

	/* Select slave. */
	if (w1_reset_select_slave(sl))
	return -EIO;

	w1_buf[0] = W1_F19_WRITE_CONFIGURATION;
	w1_buf[1] = speed;
	w1_write_block(sl->master, w1_buf, 2);

	/* Update speed in slave specific data. */
	data->speed = speed;

	dev_info(&sl->dev, "i2c speed set to %d kBaud\n", i2c_speeds[speed]);

	return 0;
	}

	static int w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
	{
	int result;

	/* Start onewire transaction. */
	mutex_lock(&sl->master->bus_mutex);

	/* Set I2C speed on DS28E17. */
	result = __w1_f19_set_i2c_speed(sl, speed);

	/* End onewire transaction. */
	mutex_unlock(&sl->master->bus_mutex);

	return result;
	}


	/* Sysfs attributes. */

	/* I2C speed attribute for a single chip. */
	static ssize_t speed_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct w1_slave *sl = dev_to_w1_slave(dev);
	int result;

	/* Read current speed from slave. Updates data->speed. */
	result = w1_f19_get_i2c_speed(sl);
	if (result < 0)
	return result;

	/* Return current speed value. */
	return sprintf(buf, "%d\n", result);
	}

	static ssize_t speed_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct w1_slave *sl = dev_to_w1_slave(dev);
	int error;

	/* Valid values are: "100", "400", "900" */
	if (count < 3 \|\| count > 4 \|\| !buf)
	return -EINVAL;
	if (count == 4 && buf[3] != '\n')
	return -EINVAL;
	if (buf[1] != '0' \|\| buf[2] != '0')
	return -EINVAL;

	/* Set speed on slave. */
	switch (buf[0]) {
	case '1':
	error = w1_f19_set_i2c_speed(sl, 0);
	break;
	case '4':
	error = w1_f19_set_i2c_speed(sl, 1);
	break;
	case '9':
	error = w1_f19_set_i2c_speed(sl, 2);
	break;
	default:
	return -EINVAL;
	}

	if (error < 0)
	return error;

	/* Return bytes written. */
	return count;
	}

	static DEVICE_ATTR_RW(speed);


	/* Busy stretch attribute for a single chip. */
	static ssize_t stretch_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct w1_slave *sl = dev_to_w1_slave(dev);
	struct w1_f19_data *data = sl->family_data;

	/* Return current stretch value. */
	return sprintf(buf, "%d\n", data->stretch);
	}

	static ssize_t stretch_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct w1_slave *sl = dev_to_w1_slave(dev);
	struct w1_f19_data *data = sl->family_data;

	/* Valid values are '1' to '9' */
	if (count < 1 \|\| count > 2 \|\| !buf)
	return -EINVAL;
	if (count == 2 && buf[1] != '\n')
	return -EINVAL;
	if (buf[0] < '1' \|\| buf[0] > '9')
	return -EINVAL;

	/* Set busy stretch value. */
	data->stretch = buf[0] & 0x0F;

	/* Return bytes written. */
	return count;
	}

	static DEVICE_ATTR_RW(stretch);


	/* All attributes. */
	static struct attribute *w1_f19_attrs[] = {
	&dev_attr_speed.attr,
	&dev_attr_stretch.attr,
	NULL,
	};

	static const struct attribute_group w1_f19_group = {
	.attrs = w1_f19_attrs,
	};

	static const struct attribute_group *w1_f19_groups[] = {
	&w1_f19_group,
	NULL,
	};


	/* Slave add and remove functions. */
	static int w1_f19_add_slave(struct w1_slave *sl)
	{
	struct w1_f19_data *data = NULL;

	/* Allocate memory for slave specific data. */
	data = devm_kzalloc(&sl->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;
	sl->family_data = data;

	/* Setup default I2C speed on slave. */
	switch (i2c_speed) {
	case 100:
	__w1_f19_set_i2c_speed(sl, 0);
	break;
	case 400:
	__w1_f19_set_i2c_speed(sl, 1);
	break;
	case 900:
	__w1_f19_set_i2c_speed(sl, 2);
	break;
	default:
	/*
	* A i2c_speed module parameter of anything else
	* than 100, 400, 900 means not to touch the
	* speed of the DS28E17.
	* We assume 400kBaud, the power-on value.
	*/
	data->speed = 1;
	}

	/*
	* Setup default busy stretch
	* configuration for the DS28E17.
	*/
	data->stretch = i2c_stretch;

	/* Setup I2C adapter. */
	data->adapter.owner = THIS_MODULE;
	data->adapter.algo = &w1_f19_i2c_algorithm;
	data->adapter.algo_data = sl;
	strcpy(data->adapter.name, "w1-");
	strcat(data->adapter.name, sl->name);
	data->adapter.dev.parent = &sl->dev;
	data->adapter.quirks = &w1_f19_i2c_adapter_quirks;

	return i2c_add_adapter(&data->adapter);
	}

	static void w1_f19_remove_slave(struct w1_slave *sl)
	{
	struct w1_f19_data *family_data = sl->family_data;

	/* Delete I2C adapter. */
	i2c_del_adapter(&family_data->adapter);

	/* Free slave specific data. */
	devm_kfree(&sl->dev, family_data);
	sl->family_data = NULL;
	}


	/* Declarations within the w1 subsystem. */
	static struct w1_family_ops w1_f19_fops = {
	.add_slave = w1_f19_add_slave,
	.remove_slave = w1_f19_remove_slave,
	.groups = w1_f19_groups,
	};

	static struct w1_family w1_family_19 = {
	.fid = W1_FAMILY_DS28E17,
	.fops = &w1_f19_fops,
	};


	/* Module init and remove functions. */
	static int __init w1_f19_init(void)
	{
	return w1_register_family(&w1_family_19);
	}

	static void __exit w1_f19_fini(void)
	{
	w1_unregister_family(&w1_family_19);
	}

	module_init(w1_f19_init);
	module_exit(w1_f19_fini);