text: /* ST Microelectronics LIS2DW12 3-axis accelerometer driver
   *
   * Copyright (c) 2019 STMicroelectronics
   *
   * SPDX-License-Identifier: Apache-2.0
   *
   * Datasheet:
   * https://www.st.com/resource/en/datasheet/lis2dw12.pdf
   */
  
  
  #include <string.h>
  #include "lis2dw12.h"
  #include <logging/log.h>
  
  #ifdef DT_ST_LIS2DW12_BUS_SPI
  
  #define LIS2DW12_SPI_READ		(1 << 7)
  
  #define LOG_LEVEL CONFIG_SENSOR_LOG_LEVEL
  LOG_MODULE_DECLARE(LIS2DW12);
  
  static struct spi_config lis2dw12_spi_conf = {
  	.frequency = DT_ST_LIS2DW12_0_SPI_MAX_FREQUENCY,
  	.operation = (SPI_OP_MODE_MASTER | SPI_MODE_CPOL |
  		      SPI_MODE_CPHA | SPI_WORD_SET(8) | SPI_LINES_SINGLE),
  	.slave     = DT_ST_LIS2DW12_0_BASE_ADDRESS,
  	.cs        = NULL,
  };
  
  static int lis2dw12_raw_read(struct lis2dw12_data *data, u8_t reg_addr,
  			    u8_t *value, u8_t len)
  {
  	struct spi_config *spi_cfg = &lis2dw12_spi_conf;
  	u8_t buffer_tx[2] = { reg_addr | LIS2DW12_SPI_READ, 0 };
  	const struct spi_buf tx_buf = {
  			.buf = buffer_tx,
  			.len = 2,
  	};
  	const struct spi_buf_set tx = {
  		.buffers = &tx_buf,
  		.count = 1
  	};
  	const struct spi_buf rx_buf[2] = {
  		{
  			.buf = NULL,
  			.len = 1,
  		},
  		{
  			.buf = value,
  			.len = len,
  		}
  	};
  	const struct spi_buf_set rx = {
  		.buffers = rx_buf,
  		.count = 2
  	};
  
  
  	if (len > 64) {
  		return -EIO;
  	}
  
  	if (spi_transceive(data->bus, spi_cfg, &tx, &rx)) {
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static int lis2dw12_raw_write(struct lis2dw12_data *data, u8_t reg_addr,
  			     u8_t *value, u8_t len)
  {
  	struct spi_config *spi_cfg = &lis2dw12_spi_conf;
  	u8_t buffer_tx[1] = { reg_addr & ~LIS2DW12_SPI_READ };
  	const struct spi_buf tx_buf[2] = {
  		{
  			.buf = buffer_tx,
  			.len = 1,
  		},
  		{
  			.buf = value,
  			.len = len,
  		}
  	};
  	const struct spi_buf_set tx = {
  		.buffers = tx_buf,
  		.count = 2
  	};
  
  
  	if (len > 64) {
  		return -EIO;
  	}
  
  	if (spi_write(data->bus, spi_cfg, &tx)) {
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static int lis2dw12_spi_read_data(struct lis2dw12_data *data, u8_t reg_addr,
  				 u8_t *value, u8_t len)
  {
  	return lis2dw12_raw_read(data, reg_addr, value, len);
  }
  
  static int lis2dw12_spi_write_data(struct lis2dw12_data *data, u8_t reg_addr,
  				  u8_t *value, u8_t len)
  {
  	return lis2dw12_raw_write(data, reg_addr, value, len);
  }
  
  static int lis2dw12_spi_read_reg(struct lis2dw12_data *data, u8_t reg_addr,
  				u8_t *value)
  {
  	return lis2dw12_raw_read(data, reg_addr, value, 1);
  }
  
  static int lis2dw12_spi_write_reg(struct lis2dw12_data *data, u8_t reg_addr,
  				u8_t value)
  {
  	u8_t tmp_val = value;
  
  	return lis2dw12_raw_write(data, reg_addr, &tmp_val, 1);
  }
  
  static int lis2dw12_spi_update_reg(struct lis2dw12_data *data, u8_t reg_addr,
  				  u8_t mask, u8_t value)
  {
  	u8_t tmp_val;
  
  	lis2dw12_raw_read(data, reg_addr, &tmp_val, 1);
  	tmp_val = (tmp_val & ~mask) | ((value  << __builtin_ctz(mask)) & mask);
  
  	return lis2dw12_raw_write(data, reg_addr, &tmp_val, 1);
  }
  
  static const struct lis2dw12_tf lis2dw12_spi_transfer_fn = {
  	.read_data = lis2dw12_spi_read_data,
  	.write_data = lis2dw12_spi_write_data,
  	.read_reg  = lis2dw12_spi_read_reg,
  	.write_reg  = lis2dw12_spi_write_reg,
  	.update_reg = lis2dw12_spi_update_reg,
  };
  
  int lis2dw12_spi_init(struct device *dev)
  {
  	struct lis2dw12_data *data = dev->driver_data;
  
  	data->hw_tf = &lis2dw12_spi_transfer_fn;
  
  #if defined(DT_ST_LIS2DW12_0_CS_GPIO_CONTROLLER)
  	/* handle SPI CS thru GPIO if it is the case */
  	data->cs_ctrl.gpio_dev = device_get_binding(
  		DT_ST_LIS2DW12_0_CS_GPIO_CONTROLLER);
  	if (!data->cs_ctrl.gpio_dev) {
  		LOG_ERR("Unable to get GPIO SPI CS device");
  		return -ENODEV;
  	}
  
  	data->cs_ctrl.gpio_pin = DT_ST_LIS2DW12_0_CS_GPIO_PIN;
  	data->cs_ctrl.delay = 0;
  
  	lis2dw12_spi_conf.cs = &data->cs_ctrl;
  
  	LOG_DBG("SPI GPIO CS configured on %s:%u",
  		    DT_ST_LIS2DW12_0_CS_GPIO_CONTROLLER,
  		    DT_ST_LIS2DW12_0_CS_GPIO_PIN);
  #endif
  
  	return 0;
  }
  #endif /* DT_ST_LIS2DW12_BUS_SPI */
  