text: /*
   * MC33880 high-side/low-side switch GPIO driver
   * Copyright (c) 2009 Intel Corporation
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  /* Supports:
   * Freescale MC33880 high-side/low-side switch
   */
  
  #include <linux/init.h>
  #include <linux/mutex.h>
  #include <linux/spi/spi.h>
  #include <linux/spi/mc33880.h>
  #include <linux/gpio.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  
  #define DRIVER_NAME "mc33880"
  
  /*
   * Pin configurations, see MAX7301 datasheet page 6
   */
  #define PIN_CONFIG_MASK 0x03
  #define PIN_CONFIG_IN_PULLUP 0x03
  #define PIN_CONFIG_IN_WO_PULLUP 0x02
  #define PIN_CONFIG_OUT 0x01
  
  #define PIN_NUMBER 8
  
  
  /*
   * Some registers must be read back to modify.
   * To save time we cache them here in memory
   */
  struct mc33880 {
  	struct mutex	lock;	/* protect from simultaneous accesses */
  	u8		port_config;
  	struct gpio_chip chip;
  	struct spi_device *spi;
  };
  
  static int mc33880_write_config(struct mc33880 *mc)
  {
  	return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  }
  
  
  static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
  {
  	if (value)
  		mc->port_config |= 1 << offset;
  	else
  		mc->port_config &= ~(1 << offset);
  
  	return mc33880_write_config(mc);
  }
  
  
  static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
  {
  	struct mc33880 *mc = gpiochip_get_data(chip);
  
  	mutex_lock(&mc->lock);
  
  	__mc33880_set(mc, offset, value);
  
  	mutex_unlock(&mc->lock);
  }
  
  static int mc33880_probe(struct spi_device *spi)
  {
  	struct mc33880 *mc;
  	struct mc33880_platform_data *pdata;
  	int ret;
  
  	pdata = dev_get_platdata(&spi->dev);
  	if (!pdata || !pdata->base) {
  		dev_dbg(&spi->dev, "incorrect or missing platform data\n");
  		return -EINVAL;
  	}
  
  	/*
  	 * bits_per_word cannot be configured in platform data
  	 */
  	spi->bits_per_word = 8;
  
  	ret = spi_setup(spi);
  	if (ret < 0)
  		return ret;
  
  	mc = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL);
  	if (!mc)
  		return -ENOMEM;
  
  	mutex_init(&mc->lock);
  
  	spi_set_drvdata(spi, mc);
  
  	mc->spi = spi;
  
  	mc->chip.label = DRIVER_NAME,
  	mc->chip.set = mc33880_set;
  	mc->chip.base = pdata->base;
  	mc->chip.ngpio = PIN_NUMBER;
  	mc->chip.can_sleep = true;
  	mc->chip.parent = &spi->dev;
  	mc->chip.owner = THIS_MODULE;
  
  	mc->port_config = 0x00;
  	/* write twice, because during initialisation the first setting
  	 * is just for testing SPI communication, and the second is the
  	 * "real" configuration
  	 */
  	ret = mc33880_write_config(mc);
  	mc->port_config = 0x00;
  	if (!ret)
  		ret = mc33880_write_config(mc);
  
  	if (ret) {
  		dev_err(&spi->dev, "Failed writing to " DRIVER_NAME ": %d\n",
  			ret);
  		goto exit_destroy;
  	}
  
  	ret = gpiochip_add_data(&mc->chip, mc);
  	if (ret)
  		goto exit_destroy;
  
  	return ret;
  
  exit_destroy:
  	mutex_destroy(&mc->lock);
  	return ret;
  }
  
  static int mc33880_remove(struct spi_device *spi)
  {
  	struct mc33880 *mc;
  
  	mc = spi_get_drvdata(spi);
  	if (!mc)
  		return -ENODEV;
  
  	gpiochip_remove(&mc->chip);
  	mutex_destroy(&mc->lock);
  
  	return 0;
  }
  
  static struct spi_driver mc33880_driver = {
  	.driver = {
  		.name		= DRIVER_NAME,
  	},
  	.probe		= mc33880_probe,
  	.remove		= mc33880_remove,
  };
  
  static int __init mc33880_init(void)
  {
  	return spi_register_driver(&mc33880_driver);
  }
  /* register after spi postcore initcall and before
   * subsys initcalls that may rely on these GPIOs
   */
  subsys_initcall(mc33880_init);
  
  static void __exit mc33880_exit(void)
  {
  	spi_unregister_driver(&mc33880_driver);
  }
  module_exit(mc33880_exit);
  
  MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
  MODULE_LICENSE("GPL v2");
  
  