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* [PATCH V4] gpio: add driver for MAX7300 I2C GPIO extender
@ 2009-12-13 16:09 Wolfram Sang
  0 siblings, 0 replies; only message in thread
From: Wolfram Sang @ 2009-12-13 16:09 UTC (permalink / raw)
  To: linux-i2c-u79uwXL29TY76Z2rM5mHXA
  Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, Wolfram Sang,
	Juergen Beisert, David Brownell, Jean Delvare, Anton Vorontsov,
	Randy Dunlap, Andrew Morton

Done by factoring out the generic routines from MAX7301 into MAX730X and
adding wrappers for MAX7300 (I2C) and MAX7301 (SPI).

Signed-off-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: Juergen Beisert <j.beisert-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: David Brownell <dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
Cc: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Cc: Anton Vorontsov <avorontsov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>
Cc: Randy Dunlap <randy.dunlap-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
---

Here is my current version which now allows to have one part as builtin and the
other as a module (discovered by Randy). Note that changes from V3 to V4 are
only built-tested (on x86 and x86-64) as I don't have access to the hardware
anymore. So, I think this should go to linux-next for another cycle.

Changes since V3:
* refactored into generic, i2c and spi part.
* no functional changes

Changes since V2:
* improve Kconfig logic. Main part depends now on I2C or SPI (Thanks again, Anton!).
  Seperate busses are now 'default y' if a bus is present, so old defconfigs will
  update automatically (it is also more convenient).
* use already present #defines instead of hardcoded values
* add some empty lines to make code more readable

Changes since V1:
* Use id_table for spi, too (Thanks to Anton for the hint!)
* removed some whitespace issues
* in driver init, remove first driver if registering the second fails

 drivers/gpio/Kconfig        |   13 ++-
 drivers/gpio/Makefile       |    2 +
 drivers/gpio/max7300.c      |   94 ++++++++++++++
 drivers/gpio/max7301.c      |  293 +++++--------------------------------------
 drivers/gpio/max730x.c      |  244 +++++++++++++++++++++++++++++++++++
 include/linux/spi/max7301.h |   18 +++
 6 files changed, 404 insertions(+), 260 deletions(-)
 create mode 100644 drivers/gpio/max7300.c
 create mode 100644 drivers/gpio/max730x.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 2ad0128..17f4206 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -65,6 +65,9 @@ config GPIO_SYSFS
 
 # put expanders in the right section, in alphabetical order
 
+config GPIO_MAX730X
+	tristate
+
 comment "Memory mapped GPIO expanders:"
 
 config GPIO_PL061
@@ -87,6 +90,13 @@ config GPIO_VR41XX
 
 comment "I2C GPIO expanders:"
 
+config GPIO_MAX7300
+	tristate "Maxim MAX7300 GPIO expander"
+	depends on I2C
+	select GPIO_MAX730X
+	help
+	  GPIO driver for Maxim MAX7301 I2C-based GPIO expander.
+
 config GPIO_MAX732X
 	tristate "MAX7319, MAX7320-7327 I2C Port Expanders"
 	depends on I2C
@@ -201,8 +211,9 @@ comment "SPI GPIO expanders:"
 config GPIO_MAX7301
 	tristate "Maxim MAX7301 GPIO expander"
 	depends on SPI_MASTER
+	select GPIO_MAX730X
 	help
-	  gpio driver for Maxim MAX7301 SPI GPIO expander.
+	  GPIO driver for Maxim MAX7301 SPI-based GPIO expander.
 
 config GPIO_MCP23S08
 	tristate "Microchip MCP23S08 I/O expander"
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 00a532c..c8ba441 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -6,6 +6,8 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 
 obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
 obj-$(CONFIG_GPIO_LANGWELL)	+= langwell_gpio.o
+obj-$(CONFIG_GPIO_MAX730X)	+= max730x.o
+obj-$(CONFIG_GPIO_MAX7300)	+= max7300.o
 obj-$(CONFIG_GPIO_MAX7301)	+= max7301.o
 obj-$(CONFIG_GPIO_MAX732X)	+= max732x.o
 obj-$(CONFIG_GPIO_MC33880)	+= mc33880.o
diff --git a/drivers/gpio/max7300.c b/drivers/gpio/max7300.c
new file mode 100644
index 0000000..9d74eef
--- /dev/null
+++ b/drivers/gpio/max7300.c
@@ -0,0 +1,94 @@
+/*
+ * drivers/gpio/max7300.c
+ *
+ * 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.
+ *
+ * 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/i2c.h>
+#include <linux/spi/max7301.h>
+
+static int max7300_i2c_write(struct device *dev, unsigned int reg,
+				unsigned int val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	return i2c_smbus_write_byte_data(client, reg, val);
+}
+
+static int max7300_i2c_read(struct device *dev, unsigned int reg)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	return i2c_smbus_read_byte_data(client, reg);
+}
+
+static int __devinit max7300_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct max7301 *ts;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+			I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	ts = kzalloc(sizeof(struct max7301), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->read = max7300_i2c_read;
+	ts->write = max7300_i2c_write;
+	ts->dev = &client->dev;
+
+	ret = __max730x_probe(ts);
+	if (ret)
+		kfree(ts);
+	return ret;
+}
+
+static int __devexit max7300_remove(struct i2c_client *client)
+{
+	return __max730x_remove(&client->dev);
+}
+
+static const struct i2c_device_id max7300_id[] = {
+	{ "max7300", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max7300_id);
+
+static struct i2c_driver max7300_driver = {
+	.driver = {
+		.name = "max7300",
+		.owner = THIS_MODULE,
+	},
+	.probe = max7300_probe,
+	.remove = __devexit_p(max7300_remove),
+	.id_table = max7300_id,
+};
+
+static int __init max7300_init(void)
+{
+	return i2c_add_driver(&max7300_driver);
+}
+subsys_initcall(max7300_init);
+
+static void __exit max7300_exit(void)
+{
+	i2c_del_driver(&max7300_driver);
+}
+module_exit(max7300_exit);
+
+MODULE_AUTHOR("Wolfram Sang");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MAX7300 GPIO-Expander");
diff --git a/drivers/gpio/max7301.c b/drivers/gpio/max7301.c
index 480956f..965d9b1 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");
diff --git a/drivers/gpio/max730x.c b/drivers/gpio/max730x.c
new file mode 100644
index 0000000..c9bced5
--- /dev/null
+++ b/drivers/gpio/max730x.c
@@ -0,0 +1,244 @@
+/**
+ * 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 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.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 = container_of(chip, struct max7301, 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);
+
+	/* Standard GPIO API doesn't support pull-ups, has to be extended.
+	 * Hard-coding no pollup for now. */
+	*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
+			   | (PIN_CONFIG_IN_WO_PULLUP << 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 = container_of(chip, struct max7301, 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 = 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) << 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 = 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);
+}
+
+int __devinit __max730x_probe(struct max7301 *ts)
+{
+	struct device *dev = ts->dev;
+	struct max7301_platform_data *pdata;
+	int i, ret;
+
+	pdata = dev->platform_data;
+	if (!pdata || !pdata->base) {
+		dev_err(dev, "incorrect or missing platform data\n");
+		return -EINVAL;
+	}
+
+	mutex_init(&ts->lock);
+	dev_set_drvdata(dev, ts);
+
+	/* Power up the chip and disable IRQ output */
+	ts->write(dev, 0x04, 0x01);
+
+	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.base = pdata->base;
+	ts->chip.ngpio = PIN_NUMBER;
+	ts->chip.can_sleep = 1;
+	ts->chip.dev = 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 */
+		ts->write(dev, 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);
+	if (ret)
+		goto exit_destroy;
+
+	return ret;
+
+exit_destroy:
+	dev_set_drvdata(dev, NULL);
+	mutex_destroy(&ts->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__max730x_probe);
+
+int __devexit __max730x_remove(struct device *dev)
+{
+	struct max7301 *ts = dev_get_drvdata(dev);
+	int ret;
+
+	if (ts == NULL)
+		return -ENODEV;
+
+	dev_set_drvdata(dev, NULL);
+
+	/* Power down the chip and disable IRQ output */
+	ts->write(dev, 0x04, 0x00);
+
+	ret = gpiochip_remove(&ts->chip);
+	if (!ret) {
+		mutex_destroy(&ts->lock);
+		kfree(ts);
+	} else
+		dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__max730x_remove);
diff --git a/include/linux/spi/max7301.h b/include/linux/spi/max7301.h
index 6dfd83f..34af0a3 100644
--- a/include/linux/spi/max7301.h
+++ b/include/linux/spi/max7301.h
@@ -1,9 +1,27 @@
 #ifndef LINUX_SPI_MAX7301_H
 #define LINUX_SPI_MAX7301_H
 
+#include <linux/gpio.h>
+
+/*
+ * 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 device *dev;
+	int (*write)(struct device *dev, unsigned int reg, unsigned int val);
+	int (*read)(struct device *dev, unsigned int reg);
+};
+
 struct max7301_platform_data {
 	/* number assigned to the first GPIO */
 	unsigned	base;
 };
 
+extern int __max730x_remove(struct device *dev);
+extern int __max730x_probe(struct max7301 *ts);
 #endif
-- 
1.6.3.3

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2009-12-13 16:09 [PATCH V4] gpio: add driver for MAX7300 I2C GPIO extender Wolfram Sang

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