gpio: add driver for MAX7300 I2C GPIO extender

Add the MAX7300-I2C variant of the MAX7301-SPI version.  Both chips share
the same core logic, so the generic part of the in-kernel SPI-driver is
refactored into a generic part.  The I2C and SPI specific funtions are
then wrapped into seperate drivers picking up the generic part.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Juergen Beisert <j.beisert@pengutronix.de>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 259 deletions

diff --git a/drivers/gpio/max7301.c b/drivers/gpio/max7301.c
index 480956f1ca50..965d9b1ea13e 100644
--- a/drivers/gpio/max7301.c
+++ b/drivers/gpio/max7301.c
@@ -1,98 +1,41 @@
-/**
+/*
  * drivers/gpio/max7301.c
  *
  * 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'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
+ * Check max730x.c for further details.
  */
 
+#include <linux/module.h>
 #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)
+/* A write to the MAX7301 means one message with one transfer */
+static int max7301_spi_write(struct device *dev, unsigned int reg,
+                                unsigned int val)
 {
+        struct spi_device *spi = to_spi_device(dev);
         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)
+/* A read from the MAX7301 means two transfers; here, one message each */
+
+static int max7301_spi_read(struct device *dev, unsigned int reg)
 {
         int ret;
         u16 word;
+        struct spi_device *spi = to_spi_device(dev);
 
         word = 0x8000 | (reg << 8);
         ret = spi_write(spi, (const u8 *)&word, sizeof(word));
@@ -108,125 +51,13 @@ static int max7301_read(struct spi_device *spi, unsigned int reg)
         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) {
-                dev_dbg(&spi->dev, "incorrect or missing platform data\n");
-                return -EINVAL;
-        }
+        int ret;
 
-        /*
-         * bits_per_word cannot be configured in platform data
-         */
+        /* bits_per_word cannot be configured in platform data */
         spi->bits_per_word = 16;
-
         ret = spi_setup(spi);
         if (ret < 0)
                 return ret;
@@ -235,90 +66,35 @@ static int __devinit max7301_probe(struct spi_device *spi)
         if (!ts)
                 return -ENOMEM;
 
-        mutex_init(&ts->lock);
-
-        dev_set_drvdata(&spi->dev, ts);
+        ts->read = max7301_spi_read;
+        ts->write = max7301_spi_write;
+        ts->dev = &spi->dev;
 
-        /* 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;
-
-        /*
-         * 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 offset = (i - 1) * 4 + j;
-                        ret = max7301_direction_input(&ts->chip, offset);
-                        if (ret)
-                                goto exit_destroy;
-                }
-        }
-
-        ret = gpiochip_add(&ts->chip);
+        ret = __max730x_probe(ts);
         if (ret)
-                goto exit_destroy;
-
-        return ret;
-
-exit_destroy:
-        dev_set_drvdata(&spi->dev, NULL);
-        mutex_destroy(&ts->lock);
-        kfree(ts);
+                kfree(ts);
         return ret;
 }
 
 static int __devexit 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;
+        return __max730x_remove(&spi->dev);
 }
 
+static const struct spi_device_id max7301_id[] = {
+        { "max7301", 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(spi, max7301_id);
+
 static struct spi_driver max7301_driver = {
         .driver = {
-                .name           = DRIVER_NAME,
-                .owner          = THIS_MODULE,
+                .name = "max7301",
+                .owner = THIS_MODULE,
         },
-        .probe          = max7301_probe,
-        .remove         = __devexit_p(max7301_remove),
+        .probe = max7301_probe,
+        .remove = __devexit_p(max7301_remove),
+        .id_table = max7301_id,
 };
 
 static int __init max7301_init(void)
@@ -336,7 +112,6 @@ static void __exit max7301_exit(void)
 }
 module_exit(max7301_exit);
 
-MODULE_AUTHOR("Juergen Beisert");
+MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
 MODULE_LICENSE("GPL v2");
-MODULE_DESCRIPTION("MAX7301 SPI based GPIO-Expander");
-MODULE_ALIAS("spi:" DRIVER_NAME);
+MODULE_DESCRIPTION("MAX7301 GPIO-Expander");