diff options
Diffstat (limited to 'drivers/gpio/gpio-max730x.c')
| -rw-r--r-- | drivers/gpio/gpio-max730x.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-max730x.c b/drivers/gpio/gpio-max730x.c new file mode 100644 index 000000000..198a36b07 --- /dev/null +++ b/drivers/gpio/gpio-max730x.c @@ -0,0 +1,245 @@ +/** + * Copyright (C) 2006 Juergen Beisert, Pengutronix + * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix + * Copyright (C) 2009 Wolfram Sang, Pengutronix + * + * 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. + * + * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are + * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more + * details + * Note: + * - DIN must be stable at the rising edge of clock. + * - when writing: + * - always clock in 16 clocks at once + * - at DIN: D15 first, D0 last + * - D0..D7 = databyte, D8..D14 = commandbyte + * - D15 = low -> write command + * - when reading + * - always clock in 16 clocks at once + * - at DIN: D15 first, D0 last + * - D0..D7 = dummy, D8..D14 = register address + * - D15 = high -> read command + * - raise CS and assert it again + * - always clock in 16 clocks at once + * - at DOUT: D15 first, D0 last + * - D0..D7 contains the data from the first cycle + * + * The driver exports a standard gpiochip interface + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/platform_device.h> +#include <linux/mutex.h> +#include <linux/spi/max7301.h> +#include <linux/gpio/driver.h> +#include <linux/slab.h> + +/* + * 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 28 + +static int max7301_direction_input(struct gpio_chip *chip, unsigned offset) +{ + struct max7301 *ts = gpiochip_get_data(chip); + u8 *config; + u8 offset_bits, pin_config; + int ret; + + /* First 4 pins are unused in the controller */ + offset += 4; + offset_bits = (offset & 3) << 1; + + config = &ts->port_config[offset >> 2]; + + if (ts->input_pullup_active & BIT(offset)) + pin_config = PIN_CONFIG_IN_PULLUP; + else + pin_config = PIN_CONFIG_IN_WO_PULLUP; + + mutex_lock(&ts->lock); + + *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) + | (pin_config << offset_bits); + + ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); + + mutex_unlock(&ts->lock); + + return ret; +} + +static int __max7301_set(struct max7301 *ts, unsigned offset, int value) +{ + if (value) { + ts->out_level |= 1 << offset; + return ts->write(ts->dev, 0x20 + offset, 0x01); + } else { + ts->out_level &= ~(1 << offset); + return ts->write(ts->dev, 0x20 + offset, 0x00); + } +} + +static int max7301_direction_output(struct gpio_chip *chip, unsigned offset, + int value) +{ + struct max7301 *ts = gpiochip_get_data(chip); + u8 *config; + u8 offset_bits; + int ret; + + /* First 4 pins are unused in the controller */ + offset += 4; + offset_bits = (offset & 3) << 1; + + config = &ts->port_config[offset >> 2]; + + mutex_lock(&ts->lock); + + *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) + | (PIN_CONFIG_OUT << offset_bits); + + ret = __max7301_set(ts, offset, value); + + if (!ret) + ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); + + mutex_unlock(&ts->lock); + + return ret; +} + +static int max7301_get(struct gpio_chip *chip, unsigned offset) +{ + struct max7301 *ts = gpiochip_get_data(chip); + int config, level = -EINVAL; + + /* First 4 pins are unused in the controller */ + offset += 4; + + mutex_lock(&ts->lock); + + config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1)) + & PIN_CONFIG_MASK; + + switch (config) { + case PIN_CONFIG_OUT: + /* Output: return cached level */ + level = !!(ts->out_level & (1 << offset)); + break; + case PIN_CONFIG_IN_WO_PULLUP: + case PIN_CONFIG_IN_PULLUP: + /* Input: read out */ + level = ts->read(ts->dev, 0x20 + offset) & 0x01; + } + mutex_unlock(&ts->lock); + + return level; +} + +static void max7301_set(struct gpio_chip *chip, unsigned offset, int value) +{ + struct max7301 *ts = gpiochip_get_data(chip); + + /* First 4 pins are unused in the controller */ + offset += 4; + + mutex_lock(&ts->lock); + + __max7301_set(ts, offset, value); + + mutex_unlock(&ts->lock); +} + +int __max730x_probe(struct max7301 *ts) +{ + struct device *dev = ts->dev; + struct max7301_platform_data *pdata; + int i, ret; + + pdata = dev_get_platdata(dev); + + mutex_init(&ts->lock); + dev_set_drvdata(dev, ts); + + /* Power up the chip and disable IRQ output */ + ts->write(dev, 0x04, 0x01); + + if (pdata) { + ts->input_pullup_active = pdata->input_pullup_active; + ts->chip.base = pdata->base; + } else { + ts->chip.base = -1; + } + ts->chip.label = dev->driver->name; + + ts->chip.direction_input = max7301_direction_input; + ts->chip.get = max7301_get; + ts->chip.direction_output = max7301_direction_output; + ts->chip.set = max7301_set; + + ts->chip.ngpio = PIN_NUMBER; + ts->chip.can_sleep = true; + ts->chip.parent = dev; + ts->chip.owner = THIS_MODULE; + + ret = gpiochip_add_data(&ts->chip, ts); + if (ret) + goto exit_destroy; + + /* + * initialize pullups according to platform data and cache the + * register values for later use. + */ + for (i = 1; i < 8; i++) { + int j; + /* + * initialize port_config with "0xAA", which means + * input with internal pullup disabled. This is needed + * to avoid writing zeros (in the inner for loop), + * which is not allowed according to the datasheet. + */ + ts->port_config[i] = 0xAA; + for (j = 0; j < 4; j++) { + int offset = (i - 1) * 4 + j; + ret = max7301_direction_input(&ts->chip, offset); + if (ret) + goto exit_destroy; + } + } + + return ret; + +exit_destroy: + mutex_destroy(&ts->lock); + return ret; +} +EXPORT_SYMBOL_GPL(__max730x_probe); + +int __max730x_remove(struct device *dev) +{ + struct max7301 *ts = dev_get_drvdata(dev); + + if (ts == NULL) + return -ENODEV; + + /* Power down the chip and disable IRQ output */ + ts->write(dev, 0x04, 0x00); + gpiochip_remove(&ts->chip); + mutex_destroy(&ts->lock); + return 0; +} +EXPORT_SYMBOL_GPL(__max730x_remove); + +MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts"); |