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248 lines
5.9 KiB
248 lines
5.9 KiB
/**
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* drivers/gpio/max7301.c
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*
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* Copyright (C) 2006 Juergen Beisert, Pengutronix
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* Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
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* Copyright (C) 2009 Wolfram Sang, Pengutronix
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
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* 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
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* details
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* Note:
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* - DIN must be stable at the rising edge of clock.
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* - when writing:
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* - always clock in 16 clocks at once
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* - at DIN: D15 first, D0 last
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* - D0..D7 = databyte, D8..D14 = commandbyte
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* - D15 = low -> write command
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* - when reading
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* - always clock in 16 clocks at once
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* - at DIN: D15 first, D0 last
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* - D0..D7 = dummy, D8..D14 = register address
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* - D15 = high -> read command
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* - raise CS and assert it again
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* - always clock in 16 clocks at once
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* - at DOUT: D15 first, D0 last
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* - D0..D7 contains the data from the first cycle
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*
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* The driver exports a standard gpiochip interface
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/mutex.h>
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#include <linux/spi/max7301.h>
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#include <linux/gpio.h>
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/*
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* Pin configurations, see MAX7301 datasheet page 6
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*/
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#define PIN_CONFIG_MASK 0x03
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#define PIN_CONFIG_IN_PULLUP 0x03
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#define PIN_CONFIG_IN_WO_PULLUP 0x02
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#define PIN_CONFIG_OUT 0x01
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#define PIN_NUMBER 28
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static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
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{
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struct max7301 *ts = container_of(chip, struct max7301, chip);
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u8 *config;
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u8 offset_bits;
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int ret;
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/* First 4 pins are unused in the controller */
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offset += 4;
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offset_bits = (offset & 3) << 1;
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config = &ts->port_config[offset >> 2];
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mutex_lock(&ts->lock);
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/* Standard GPIO API doesn't support pull-ups, has to be extended.
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* Hard-coding no pollup for now. */
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*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
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| (PIN_CONFIG_IN_WO_PULLUP << offset_bits);
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ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
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mutex_unlock(&ts->lock);
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return ret;
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}
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static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
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{
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if (value) {
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ts->out_level |= 1 << offset;
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return ts->write(ts->dev, 0x20 + offset, 0x01);
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} else {
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ts->out_level &= ~(1 << offset);
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return ts->write(ts->dev, 0x20 + offset, 0x00);
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}
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}
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static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
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int value)
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{
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struct max7301 *ts = container_of(chip, struct max7301, chip);
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u8 *config;
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u8 offset_bits;
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int ret;
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/* First 4 pins are unused in the controller */
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offset += 4;
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offset_bits = (offset & 3) << 1;
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config = &ts->port_config[offset >> 2];
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mutex_lock(&ts->lock);
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*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
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| (PIN_CONFIG_OUT << offset_bits);
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ret = __max7301_set(ts, offset, value);
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if (!ret)
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ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
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mutex_unlock(&ts->lock);
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return ret;
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}
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static int max7301_get(struct gpio_chip *chip, unsigned offset)
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{
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struct max7301 *ts = container_of(chip, struct max7301, chip);
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int config, level = -EINVAL;
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/* First 4 pins are unused in the controller */
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offset += 4;
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mutex_lock(&ts->lock);
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config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
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& PIN_CONFIG_MASK;
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switch (config) {
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case PIN_CONFIG_OUT:
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/* Output: return cached level */
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level = !!(ts->out_level & (1 << offset));
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break;
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case PIN_CONFIG_IN_WO_PULLUP:
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case PIN_CONFIG_IN_PULLUP:
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/* Input: read out */
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level = ts->read(ts->dev, 0x20 + offset) & 0x01;
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}
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mutex_unlock(&ts->lock);
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return level;
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}
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static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
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{
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struct max7301 *ts = container_of(chip, struct max7301, chip);
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/* First 4 pins are unused in the controller */
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offset += 4;
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mutex_lock(&ts->lock);
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__max7301_set(ts, offset, value);
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mutex_unlock(&ts->lock);
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}
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int __devinit __max730x_probe(struct max7301 *ts)
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{
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struct device *dev = ts->dev;
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struct max7301_platform_data *pdata;
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int i, ret;
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pdata = dev->platform_data;
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if (!pdata || !pdata->base) {
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dev_err(dev, "incorrect or missing platform data\n");
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return -EINVAL;
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}
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mutex_init(&ts->lock);
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dev_set_drvdata(dev, ts);
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/* Power up the chip and disable IRQ output */
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ts->write(dev, 0x04, 0x01);
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ts->chip.label = dev->driver->name;
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ts->chip.direction_input = max7301_direction_input;
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ts->chip.get = max7301_get;
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ts->chip.direction_output = max7301_direction_output;
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ts->chip.set = max7301_set;
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ts->chip.base = pdata->base;
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ts->chip.ngpio = PIN_NUMBER;
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ts->chip.can_sleep = 1;
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ts->chip.dev = dev;
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ts->chip.owner = THIS_MODULE;
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/*
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* tristate all pins in hardware and cache the
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* register values for later use.
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*/
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for (i = 1; i < 8; i++) {
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int j;
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/* 0xAA means input with internal pullup disabled */
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ts->write(dev, 0x08 + i, 0xAA);
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ts->port_config[i] = 0xAA;
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for (j = 0; j < 4; j++) {
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int offset = (i - 1) * 4 + j;
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ret = max7301_direction_input(&ts->chip, offset);
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if (ret)
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goto exit_destroy;
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}
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}
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ret = gpiochip_add(&ts->chip);
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if (ret)
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goto exit_destroy;
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return ret;
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exit_destroy:
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dev_set_drvdata(dev, NULL);
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mutex_destroy(&ts->lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(__max730x_probe);
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int __devexit __max730x_remove(struct device *dev)
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{
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struct max7301 *ts = dev_get_drvdata(dev);
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int ret;
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if (ts == NULL)
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return -ENODEV;
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dev_set_drvdata(dev, NULL);
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/* Power down the chip and disable IRQ output */
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ts->write(dev, 0x04, 0x00);
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ret = gpiochip_remove(&ts->chip);
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if (!ret) {
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mutex_destroy(&ts->lock);
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kfree(ts);
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} else
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dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
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return ret;
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}
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EXPORT_SYMBOL_GPL(__max730x_remove);
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MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
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