diff options
| -rw-r--r-- | drivers/gpio/Kconfig | 6 | ||||
| -rw-r--r-- | drivers/gpio/Makefile | 1 | ||||
| -rw-r--r-- | drivers/gpio/max7301.c | 339 | ||||
| -rw-r--r-- | include/linux/spi/max7301.h | 9 |
4 files changed, 355 insertions, 0 deletions
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 008c38ba774..9e0c4fbfc51 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -69,6 +69,12 @@ config GPIO_PCF857X comment "SPI GPIO expanders:" +config GPIO_MAX7301 + tristate "Maxim MAX7301 GPIO expander" + depends on SPI_MASTER + help + gpio driver for Maxim MAX7301 SPI GPIO expander. + config GPIO_MCP23S08 tristate "Microchip MCP23S08 I/O expander" depends on SPI_MASTER diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index fdde9923cf3..16e796dc541 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -4,6 +4,7 @@ ccflags-$(CONFIG_DEBUG_GPIO) += -DDEBUG obj-$(CONFIG_HAVE_GPIO_LIB) += gpiolib.o +obj-$(CONFIG_GPIO_MAX7301) += max7301.o obj-$(CONFIG_GPIO_MCP23S08) += mcp23s08.o obj-$(CONFIG_GPIO_PCA953X) += pca953x.o obj-$(CONFIG_GPIO_PCF857X) += pcf857x.o diff --git a/drivers/gpio/max7301.c b/drivers/gpio/max7301.c new file mode 100644 index 00000000000..39c795ad831 --- /dev/null +++ b/drivers/gpio/max7301.c @@ -0,0 +1,339 @@ +/** + * drivers/gpio/max7301.c + * + * Copyright (C) 2006 Juergen Beisert, Pengutronix + * Copyright (C) 2008 Guennadi Liakhovetski, 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's MAX7301 device is an 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/init.h> +#include <linux/platform_device.h> +#include <linux/mutex.h> +#include <linux/spi/spi.h> +#include <linux/spi/max7301.h> +#include <linux/gpio.h> + +#define DRIVER_NAME "max7301" + +/* + * 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 + + +/* + * Some registers must be read back to modify. + * To save time we cache them here in memory + */ +struct max7301 { + struct mutex lock; + u8 port_config[8]; /* field 0 is unused */ + u32 out_level; /* cached output levels */ + struct gpio_chip chip; + struct spi_device *spi; +}; + +/** + * max7301_write - Write a new register content + * @spi: The SPI device + * @reg: Register offset + * @val: Value to write + * + * A write to the MAX7301 means one message with one transfer + * + * Returns 0 if successful or a negative value on error + */ +static int max7301_write(struct spi_device *spi, unsigned int reg, unsigned int val) +{ + u16 word = ((reg & 0x7F) << 8) | (val & 0xFF); + return spi_write(spi, (const u8 *)&word, sizeof(word)); +} + +/** + * max7301_read - Read back register content + * @spi: The SPI device + * @reg: Register offset + * + * A read from the MAX7301 means two transfers; here, one message each + * + * Returns positive 8 bit value from device if successful or a + * negative value on error + */ +static int max7301_read(struct spi_device *spi, unsigned int reg) +{ + int ret; + u16 word; + + word = 0x8000 | (reg << 8); + ret = spi_write(spi, (const u8 *)&word, sizeof(word)); + if (ret) + return ret; + /* + * This relies on the fact, that a transfer with NULL tx_buf shifts out + * zero bytes (=NOOP for MAX7301) + */ + ret = spi_read(spi, (u8 *)&word, sizeof(word)); + if (ret) + return ret; + return word & 0xff; +} + +static int max7301_direction_input(struct gpio_chip *chip, unsigned offset) +{ + struct max7301 *ts = container_of(chip, struct max7301, chip); + u8 *config; + int ret; + + /* First 4 pins are unused in the controller */ + offset += 4; + + config = &ts->port_config[offset >> 2]; + + mutex_lock(&ts->lock); + + /* Standard GPIO API doesn't support pull-ups, has to be extended. + * Hard-coding no pollup for now. */ + *config = (*config & ~(3 << (offset & 3))) | (1 << (offset & 3)); + + ret = max7301_write(ts->spi, 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 max7301_write(ts->spi, 0x20 + offset, 0x01); + } else { + ts->out_level &= ~(1 << offset); + return max7301_write(ts->spi, 0x20 + offset, 0x00); + } +} + +static int max7301_direction_output(struct gpio_chip *chip, unsigned offset, + int value) +{ + struct max7301 *ts = container_of(chip, struct max7301, chip); + u8 *config; + int ret; + + /* First 4 pins are unused in the controller */ + offset += 4; + + config = &ts->port_config[offset >> 2]; + + mutex_lock(&ts->lock); + + *config = (*config & ~(3 << (offset & 3))) | (1 << (offset & 3)); + + ret = __max7301_set(ts, offset, value); + + if (!ret) + ret = max7301_write(ts->spi, 0x08 + (offset >> 2), *config); + + mutex_unlock(&ts->lock); + + return ret; +} + +static int max7301_get(struct gpio_chip *chip, unsigned offset) +{ + struct max7301 *ts = container_of(chip, struct max7301, 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) * 2)) & 3; + + switch (config) { + case 1: + /* Output: return cached level */ + level = !!(ts->out_level & (1 << offset)); + break; + case 2: + case 3: + /* Input: read out */ + level = max7301_read(ts->spi, 0x20 + offset) & 0x01; + } + mutex_unlock(&ts->lock); + + return level; +} + +static void max7301_set(struct gpio_chip *chip, unsigned offset, int value) +{ + struct max7301 *ts = container_of(chip, struct max7301, chip); + + /* First 4 pins are unused in the controller */ + offset += 4; + + mutex_lock(&ts->lock); + + __max7301_set(ts, offset, value); + + mutex_unlock(&ts->lock); +} + +static int __devinit max7301_probe(struct spi_device *spi) +{ + struct max7301 *ts; + struct max7301_platform_data *pdata; + int i, ret; + + pdata = spi->dev.platform_data; + if (!pdata || !pdata->base) + return -ENODEV; + + /* + * bits_per_word cannot be configured in platform data + */ + spi->bits_per_word = 16; + + ret = spi_setup(spi); + if (ret < 0) + return ret; + + ts = kzalloc(sizeof(struct max7301), GFP_KERNEL); + if (!ts) + return -ENOMEM; + + mutex_init(&ts->lock); + + dev_set_drvdata(&spi->dev, ts); + + /* Power up the chip and disable IRQ output */ + max7301_write(spi, 0x04, 0x01); + + ts->spi = spi; + + ts->chip.label = 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.base = pdata->base; + ts->chip.ngpio = PIN_NUMBER; + ts->chip.can_sleep = 1; + ts->chip.dev = &spi->dev; + ts->chip.owner = THIS_MODULE; + + ret = gpiochip_add(&ts->chip); + if (ret) + goto exit_destroy; + + /* + * tristate all pins in hardware and cache the + * register values for later use. + */ + for (i = 1; i < 8; i++) { + int j; + /* 0xAA means input with internal pullup disabled */ + max7301_write(spi, 0x08 + i, 0xAA); + ts->port_config[i] = 0xAA; + for (j = 0; j < 4; j++) { + int idx = ts->chip.base + (i - 1) * 4 + j; + ret = gpio_direction_input(idx); + if (ret) + goto exit_remove; + gpio_free(idx); + } + } + return ret; + +exit_remove: + gpiochip_remove(&ts->chip); +exit_destroy: + dev_set_drvdata(&spi->dev, NULL); + mutex_destroy(&ts->lock); + kfree(ts); + return ret; +} + +static int max7301_remove(struct spi_device *spi) +{ + struct max7301 *ts; + int ret; + + ts = dev_get_drvdata(&spi->dev); + if (ts == NULL) + return -ENODEV; + + dev_set_drvdata(&spi->dev, NULL); + + /* Power down the chip and disable IRQ output */ + max7301_write(spi, 0x04, 0x00); + + ret = gpiochip_remove(&ts->chip); + if (!ret) { + mutex_destroy(&ts->lock); + kfree(ts); + } else + dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n", + ret); + + return ret; +} + +static struct spi_driver max7301_driver = { + .driver = { + .name = DRIVER_NAME, + .owner = THIS_MODULE, + }, + .probe = max7301_probe, + .remove = __devexit_p(max7301_remove), +}; + +static int __init max7301_init(void) +{ + return spi_register_driver(&max7301_driver); +} + +static void __exit max7301_exit(void) +{ + spi_unregister_driver(&max7301_driver); +} + +module_init(max7301_init); +module_exit(max7301_exit); + +MODULE_AUTHOR("Juergen Beisert"); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("MAX7301 SPI based GPIO-Expander"); diff --git a/include/linux/spi/max7301.h b/include/linux/spi/max7301.h new file mode 100644 index 00000000000..6dfd83f19b4 --- /dev/null +++ b/include/linux/spi/max7301.h @@ -0,0 +1,9 @@ +#ifndef LINUX_SPI_MAX7301_H +#define LINUX_SPI_MAX7301_H + +struct max7301_platform_data { + /* number assigned to the first GPIO */ + unsigned base; +}; + +#endif |