text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * Hardware monitoring driver for the STPDDC60 controller
   *
   * Copyright (c) 2021 Flextronics International Sweden AB.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/pmbus.h>
  #include "pmbus.h"
  
  #define STPDDC60_MFR_READ_VOUT		0xd2
  #define STPDDC60_MFR_OV_LIMIT_OFFSET	0xe5
  #define STPDDC60_MFR_UV_LIMIT_OFFSET	0xe6
  
  static const struct i2c_device_id stpddc60_id[] = {
  	{"stpddc60", 0},
  	{"bmr481", 0},
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, stpddc60_id);
  
  static struct pmbus_driver_info stpddc60_info = {
  	.pages = 1,
  	.func[0] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
  		| PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
  		| PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP
  		| PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
  		| PMBUS_HAVE_POUT,
  };
  
  /*
   * Calculate the closest absolute offset between commanded vout value
   * and limit value in steps of 50mv in the range 0 (50mv) to 7 (400mv).
   * Return 0 if the upper limit is lower than vout or if the lower limit
   * is higher than vout.
   */
  static u8 stpddc60_get_offset(int vout, u16 limit, bool over)
  {
  	int offset;
  	long v, l;
  
  	v = 250 + (vout - 1) * 5; /* Convert VID to mv */
  	l = (limit * 1000L) >> 8; /* Convert LINEAR to mv */
  
  	if (over == (l < v))
  		return 0;
  
  	offset = DIV_ROUND_CLOSEST(abs(l - v), 50);
  
  	if (offset > 0)
  		offset--;
  
  	return clamp_val(offset, 0, 7);
  }
  
  /*
   * Adjust the linear format word to use the given fixed exponent.
   */
  static u16 stpddc60_adjust_linear(u16 word, s16 fixed)
  {
  	s16 e, m, d;
  
  	e = ((s16)word) >> 11;
  	m = ((s16)((word & 0x7ff) << 5)) >> 5;
  	d = e - fixed;
  
  	if (d >= 0)
  		m <<= d;
  	else
  		m >>= -d;
  
  	return clamp_val(m, 0, 0x3ff) | ((fixed << 11) & 0xf800);
  }
  
  /*
   * The VOUT_COMMAND register uses the VID format but the vout alarm limit
   * registers use the LINEAR format so we override VOUT_MODE here to force
   * LINEAR format for all registers.
   */
  static int stpddc60_read_byte_data(struct i2c_client *client, int page, int reg)
  {
  	int ret;
  
  	if (page > 0)
  		return -ENXIO;
  
  	switch (reg) {
  	case PMBUS_VOUT_MODE:
  		ret = 0x18;
  		break;
  	default:
  		ret = -ENODATA;
  		break;
  	}
  
  	return ret;
  }
  
  /*
   * The vout related registers return values in LINEAR11 format when LINEAR16
   * is expected. Clear the top 5 bits to set the exponent part to zero to
   * convert the value to LINEAR16 format.
   */
  static int stpddc60_read_word_data(struct i2c_client *client, int page,
  				   int phase, int reg)
  {
  	int ret;
  
  	if (page > 0)
  		return -ENXIO;
  
  	switch (reg) {
  	case PMBUS_READ_VOUT:
  		ret = pmbus_read_word_data(client, page, phase,
  					   STPDDC60_MFR_READ_VOUT);
  		if (ret < 0)
  			return ret;
  		ret &= 0x7ff;
  		break;
  	case PMBUS_VOUT_OV_FAULT_LIMIT:
  	case PMBUS_VOUT_UV_FAULT_LIMIT:
  		ret = pmbus_read_word_data(client, page, phase, reg);
  		if (ret < 0)
  			return ret;
  		ret &= 0x7ff;
  		break;
  	default:
  		ret = -ENODATA;
  		break;
  	}
  
  	return ret;
  }
  
  /*
   * The vout under- and over-voltage limits are set as an offset relative to
   * the commanded vout voltage. The vin, iout, pout and temp limits must use
   * the same fixed exponent the chip uses to encode the data when read.
   */
  static int stpddc60_write_word_data(struct i2c_client *client, int page,
  				    int reg, u16 word)
  {
  	int ret;
  	u8 offset;
  
  	if (page > 0)
  		return -ENXIO;
  
  	switch (reg) {
  	case PMBUS_VOUT_OV_FAULT_LIMIT:
  		ret = pmbus_read_word_data(client, page, 0xff,
  					   PMBUS_VOUT_COMMAND);
  		if (ret < 0)
  			return ret;
  		offset = stpddc60_get_offset(ret, word, true);
  		ret = pmbus_write_byte_data(client, page,
  					    STPDDC60_MFR_OV_LIMIT_OFFSET,
  					    offset);
  		break;
  	case PMBUS_VOUT_UV_FAULT_LIMIT:
  		ret = pmbus_read_word_data(client, page, 0xff,
  					   PMBUS_VOUT_COMMAND);
  		if (ret < 0)
  			return ret;
  		offset = stpddc60_get_offset(ret, word, false);
  		ret = pmbus_write_byte_data(client, page,
  					    STPDDC60_MFR_UV_LIMIT_OFFSET,
  					    offset);
  		break;
  	case PMBUS_VIN_OV_FAULT_LIMIT:
  	case PMBUS_VIN_UV_FAULT_LIMIT:
  	case PMBUS_OT_FAULT_LIMIT:
  	case PMBUS_OT_WARN_LIMIT:
  	case PMBUS_IOUT_OC_FAULT_LIMIT:
  	case PMBUS_IOUT_OC_WARN_LIMIT:
  	case PMBUS_POUT_OP_FAULT_LIMIT:
  		ret = pmbus_read_word_data(client, page, 0xff, reg);
  		if (ret < 0)
  			return ret;
  		word = stpddc60_adjust_linear(word, ret >> 11);
  		ret = pmbus_write_word_data(client, page, reg, word);
  		break;
  	default:
  		ret = -ENODATA;
  		break;
  	}
  
  	return ret;
  }
  
  static int stpddc60_probe(struct i2c_client *client)
  {
  	int status;
  	u8 device_id[I2C_SMBUS_BLOCK_MAX + 1];
  	const struct i2c_device_id *mid;
  	struct pmbus_driver_info *info = &stpddc60_info;
  
  	if (!i2c_check_functionality(client->adapter,
  				     I2C_FUNC_SMBUS_READ_BYTE_DATA
  				     | I2C_FUNC_SMBUS_BLOCK_DATA))
  		return -ENODEV;
  
  	status = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, device_id);
  	if (status < 0) {
  		dev_err(&client->dev, "Failed to read Manufacturer Model\n");
  		return status;
  	}
  	for (mid = stpddc60_id; mid->name[0]; mid++) {
  		if (!strncasecmp(mid->name, device_id, strlen(mid->name)))
  			break;
  	}
  	if (!mid->name[0]) {
  		dev_err(&client->dev, "Unsupported device\n");
  		return -ENODEV;
  	}
  
  	info->read_byte_data = stpddc60_read_byte_data;
  	info->read_word_data = stpddc60_read_word_data;
  	info->write_word_data = stpddc60_write_word_data;
  
  	status = pmbus_do_probe(client, info);
  	if (status < 0)
  		return status;
  
  	pmbus_set_update(client, PMBUS_VOUT_OV_FAULT_LIMIT, true);
  	pmbus_set_update(client, PMBUS_VOUT_UV_FAULT_LIMIT, true);
  
  	return 0;
  }
  
  static struct i2c_driver stpddc60_driver = {
  	.driver = {
  		   .name = "stpddc60",
  		   },
  	.probe_new = stpddc60_probe,
  	.id_table = stpddc60_id,
  };
  
  module_i2c_driver(stpddc60_driver);
  
  MODULE_AUTHOR("Erik Rosen <erik.rosen@metormote.com>");
  MODULE_DESCRIPTION("PMBus driver for ST STPDDC60");
  MODULE_LICENSE("GPL");
  MODULE_IMPORT_NS(PMBUS);
  