[PATCH] max730x: make pullups configurable via platformdata

[PATCH] max730x: make pullups configurable via platformdata

[Marc Kleine-Budde]

The gpios on the max730x chips have support for internal pullups
while in input mode.

This patch adds support for configuring these pullups via platform data.
A new member ("input_pullup_active") to the platform data struct is
introduced. A set bit in this variable activates the pullups while the
respective port is in input mode. This is a compatible enhancement since
unset bits lead to disables pullups which was the default in the
original driver.

_Note_: the 4 lowest bits in "input_pullup_active" are unused because
the first 4 ports of the controller are not used, too.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/gpio/max730x.c      |   22 +++++++++++++++-------
 include/linux/spi/max7301.h |    8 ++++++++
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/max730x.c b/drivers/gpio/max730x.c
index 7696a56..94ce773 100644
--- a/drivers/gpio/max730x.c
+++ b/drivers/gpio/max730x.c
@@ -54,7 +54,7 @@ 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;
+	u8 offset_bits, pin_config;
 	int ret;
 
 	/* First 4 pins are unused in the controller */
@@ -63,12 +63,15 @@ static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
 
 	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);
 
-	/* 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);
+			   | (pin_config << offset_bits);
 
 	ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
 
@@ -177,6 +180,7 @@ int __devinit __max730x_probe(struct max7301 *ts)
 	/* Power up the chip and disable IRQ output */
 	ts->write(dev, 0x04, 0x01);
 
+	ts->input_pullup_active = pdata->input_pullup_active;
 	ts->chip.label = dev->driver->name;
 
 	ts->chip.direction_input = max7301_direction_input;
@@ -191,13 +195,17 @@ int __devinit __max730x_probe(struct max7301 *ts)
 	ts->chip.owner = THIS_MODULE;
 
 	/*
-	 * tristate all pins in hardware and cache the
+	 * initialize pullups according to platform data 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);
+		/*
+		 * 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;
diff --git a/include/linux/spi/max7301.h b/include/linux/spi/max7301.h
index 34af0a3..bcaa2f7 100644
--- a/include/linux/spi/max7301.h
+++ b/include/linux/spi/max7301.h
@@ -11,6 +11,7 @@ struct max7301 {
 	struct mutex	lock;
 	u8		port_config[8];	/* field 0 is unused */
 	u32		out_level;	/* cached output levels */
+	u32		input_pullup_active;
 	struct gpio_chip chip;
 	struct device *dev;
 	int (*write)(struct device *dev, unsigned int reg, unsigned int val);
@@ -20,6 +21,13 @@ struct max7301 {
 struct max7301_platform_data {
 	/* number assigned to the first GPIO */
 	unsigned	base;
+	/*
+	 * bitmask controlling the pullup configuration,
+	 *
+	 * _note_ the 4 lowest bits are unused, because the first 4
+	 * ports of the controller are not used, too.
+	 */
+	u32		input_pullup_active;
 };
 
 extern int __max730x_remove(struct device *dev);
-- 
1.7.1

Re: [PATCH] max730x: make pullups configurable via platformdata

[Wolfram Sang]

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On Tue, Jun 15, 2010 at 10:01:01AM +0200, Marc Kleine-Budde wrote:
> The gpios on the max730x chips have support for internal pullups
> while in input mode.
> 
> This patch adds support for configuring these pullups via platform data.
> A new member ("input_pullup_active") to the platform data struct is
> introduced. A set bit in this variable activates the pullups while the
> respective port is in input mode. This is a compatible enhancement since
> unset bits lead to disables pullups which was the default in the
> original driver.
> 
> _Note_: the 4 lowest bits in "input_pullup_active" are unused because
> the first 4 ports of the controller are not used, too.
> 
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Marc an I already discussed the previous versions, so:

Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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