path: root/recipes-kernel/linux/files/0015-Quark-GPIO-1-2-quark.patch

From xxxx Mon Sep 17 00:00:00 2001
From: Josef Ahmad <josef.ahmad@linux.intel.com>
Date: Wed, 9 Apr 2014 16:57:30 +0100
Subject: [PATCH 15/21] Quark GPIO 1/2

---
 drivers/gpio/Kconfig        |   9 +-
 drivers/gpio/gpio-pca953x.c | 235 ++++++++++++++++++++++++++++++++++----------
 drivers/gpio/gpiolib.c      | 130 ++++++++++++++++++++++++
 include/asm-generic/gpio.h  |   4 +
 include/linux/gpio.h        |  10 ++
 5 files changed, 332 insertions(+), 56 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 682de75..447e51a 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -243,13 +243,14 @@ config GPIO_VR41XX
 	  Say yes here to support the NEC VR4100 series General-purpose I/O Uint
 
 config GPIO_SCH
-	tristate "Intel SCH/TunnelCreek/Centerton GPIO"
+	tristate "Intel SCH/TunnelCreek/Centerton/Quark GPIO"
 	depends on PCI && X86
 	select MFD_CORE
 	select LPC_SCH
 	help
 	  Say yes here to support GPIO interface on Intel Poulsbo SCH,
-	  Intel Tunnel Creek processor or Intel Centerton processor.
+	  Intel Tunnel Creek processor, Intel Centerton processor or Intel
+	  Quark.
 	  The Intel SCH contains a total of 14 GPIO pins. Ten GPIOs are
 	  powered by the core power rail and are turned off during sleep
 	  modes (S3 and higher). The remaining four GPIOs are powered by
@@ -261,6 +262,8 @@ config GPIO_SCH
 	  The Intel Centerton processor has a total of 30 GPIO pins.
 	  Twenty-one are powered by the core power rail and 9 from the
 	  suspend power supply.
+	  The Intel Quark has 2 GPIOs powered by the core power well and 6
+	  form the suspend power well.
 
 config GPIO_ICH
 	tristate "Intel ICH GPIO"
@@ -363,7 +366,7 @@ config GPIO_PCA953X
 
 config GPIO_PCA953X_IRQ
 	bool "Interrupt controller support for PCA953x"
-	depends on GPIO_PCA953X=y
+	depends on GPIO_PCA953X
 	help
 	  Say yes here to enable the pca953x to be used as an interrupt
 	  controller. It requires the driver to be built in the kernel.
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index cc102d2..6ac3b87 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -29,6 +29,12 @@
 #define PCA953X_INVERT		2
 #define PCA953X_DIRECTION	3
 
+#define PCAL953X_IN_LATCH	34
+#define PCAL953X_PUPD_EN	35
+#define PCAL953X_PUPD_SEL	36
+#define PCAL953X_INT_MASK	37
+#define PCAL953X_INT_STAT	38
+
 #define REG_ADDR_AI		0x80
 
 #define PCA957X_IN		0
@@ -44,29 +50,32 @@
 #define PCA_INT			0x0100
 #define PCA953X_TYPE		0x1000
 #define PCA957X_TYPE		0x2000
+#define PCAL953X_TYPE		0x4000
+
 
 static const struct i2c_device_id pca953x_id[] = {
-	{ "pca9534", 8  | PCA953X_TYPE | PCA_INT, },
-	{ "pca9535", 16 | PCA953X_TYPE | PCA_INT, },
-	{ "pca9536", 4  | PCA953X_TYPE, },
-	{ "pca9537", 4  | PCA953X_TYPE | PCA_INT, },
-	{ "pca9538", 8  | PCA953X_TYPE | PCA_INT, },
-	{ "pca9539", 16 | PCA953X_TYPE | PCA_INT, },
-	{ "pca9554", 8  | PCA953X_TYPE | PCA_INT, },
-	{ "pca9555", 16 | PCA953X_TYPE | PCA_INT, },
-	{ "pca9556", 8  | PCA953X_TYPE, },
-	{ "pca9557", 8  | PCA953X_TYPE, },
-	{ "pca9574", 8  | PCA957X_TYPE | PCA_INT, },
-	{ "pca9575", 16 | PCA957X_TYPE | PCA_INT, },
-
-	{ "max7310", 8  | PCA953X_TYPE, },
-	{ "max7312", 16 | PCA953X_TYPE | PCA_INT, },
-	{ "max7313", 16 | PCA953X_TYPE | PCA_INT, },
-	{ "max7315", 8  | PCA953X_TYPE | PCA_INT, },
-	{ "pca6107", 8  | PCA953X_TYPE | PCA_INT, },
-	{ "tca6408", 8  | PCA953X_TYPE | PCA_INT, },
-	{ "tca6416", 16 | PCA953X_TYPE | PCA_INT, },
-	{ "tca6424", 24 | PCA953X_TYPE | PCA_INT, },
+	{ "pca9534",   8  | PCA953X_TYPE | PCA_INT, },
+	{ "pca9535",   16 | PCA953X_TYPE | PCA_INT, },
+	{ "pca9536",   4  | PCA953X_TYPE, },
+	{ "pca9537",   4  | PCA953X_TYPE | PCA_INT, },
+	{ "pca9538",   8  | PCA953X_TYPE | PCA_INT, },
+	{ "pca9539",   16 | PCA953X_TYPE | PCA_INT, },
+	{ "pca9554",   8  | PCA953X_TYPE | PCA_INT, },
+	{ "pca9555",   16 | PCA953X_TYPE | PCA_INT, },
+	{ "pcal9555a", 16 | PCAL953X_TYPE | PCA_INT, },
+	{ "pca9556",   8  | PCA953X_TYPE, },
+	{ "pca9557",   8  | PCA953X_TYPE, },
+	{ "pca9574",   8  | PCA957X_TYPE | PCA_INT, },
+	{ "pca9575",   16 | PCA957X_TYPE | PCA_INT, },
+
+	{ "max7310",   8  | PCA953X_TYPE, },
+	{ "max7312",   16 | PCA953X_TYPE | PCA_INT, },
+	{ "max7313",   16 | PCA953X_TYPE | PCA_INT, },
+	{ "max7315",   8  | PCA953X_TYPE | PCA_INT, },
+	{ "pca6107",   8  | PCA953X_TYPE | PCA_INT, },
+	{ "tca6408",   8  | PCA953X_TYPE | PCA_INT, },
+	{ "tca6416",   16 | PCA953X_TYPE | PCA_INT, },
+	{ "tca6424",   24 | PCA953X_TYPE | PCA_INT, },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, pca953x_id);
@@ -75,6 +84,8 @@ struct pca953x_chip {
 	unsigned gpio_start;
 	u32 reg_output;
 	u32 reg_direction;
+	u32 reg_pupd_en;
+	u32 reg_pupd_sel;
 	struct mutex i2c_lock;
 
 #ifdef CONFIG_GPIO_PCA953X_IRQ
@@ -105,9 +116,9 @@ static int pca953x_write_reg(struct pca953x_chip *chip, int reg, u32 val)
 						(reg << 2) | REG_ADDR_AI,
 						3,
 						(u8 *) &val);
-	}
-	else {
+	} else {
 		switch (chip->chip_type) {
+		case PCAL953X_TYPE:
 		case PCA953X_TYPE:
 			ret = i2c_smbus_write_word_data(chip->client,
 							reg << 1, val);
@@ -139,8 +150,7 @@ static int pca953x_read_reg(struct pca953x_chip *chip, int reg, u32 *val)
 	if (chip->gpio_chip.ngpio <= 8) {
 		ret = i2c_smbus_read_byte_data(chip->client, reg);
 		*val = ret;
-	}
-	else if (chip->gpio_chip.ngpio == 24) {
+	} else if (chip->gpio_chip.ngpio == 24) {
 		*val = 0;
 		ret = i2c_smbus_read_i2c_block_data(chip->client,
 						(reg << 2) | REG_ADDR_AI,
@@ -172,6 +182,7 @@ static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
 	reg_val = chip->reg_direction | (1u << off);
 
 	switch (chip->chip_type) {
+	case PCAL953X_TYPE:
 	case PCA953X_TYPE:
 		offset = PCA953X_DIRECTION;
 		break;
@@ -207,6 +218,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc,
 		reg_val = chip->reg_output & ~(1u << off);
 
 	switch (chip->chip_type) {
+	case PCAL953X_TYPE:
 	case PCA953X_TYPE:
 		offset = PCA953X_OUTPUT;
 		break;
@@ -223,6 +235,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc,
 	/* then direction */
 	reg_val = chip->reg_direction & ~(1u << off);
 	switch (chip->chip_type) {
+	case PCAL953X_TYPE:
 	case PCA953X_TYPE:
 		offset = PCA953X_DIRECTION;
 		break;
@@ -251,6 +264,7 @@ static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
 
 	mutex_lock(&chip->i2c_lock);
 	switch (chip->chip_type) {
+	case PCAL953X_TYPE:
 	case PCA953X_TYPE:
 		offset = PCA953X_INPUT;
 		break;
@@ -286,6 +300,7 @@ static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
 		reg_val = chip->reg_output & ~(1u << off);
 
 	switch (chip->chip_type) {
+	case PCAL953X_TYPE:
 	case PCA953X_TYPE:
 		offset = PCA953X_OUTPUT;
 		break;
@@ -302,6 +317,60 @@ exit:
 	mutex_unlock(&chip->i2c_lock);
 }
 
+static int pca953x_gpio_set_drive(struct gpio_chip *gc,
+				  unsigned off, unsigned mode)
+{
+	struct pca953x_chip *chip;
+	u32 pupd_en_reg_val, pupd_sel_reg_val;
+	int ret = 0;
+
+	chip = container_of(gc, struct pca953x_chip, gpio_chip);
+
+	if (chip->chip_type != PCAL953X_TYPE)
+		return -EINVAL;
+
+	mutex_lock(&chip->i2c_lock);
+
+	switch (mode) {
+	case GPIOF_DRIVE_PULLUP:
+		pupd_en_reg_val = chip->reg_pupd_en | (1u << off);
+		pupd_sel_reg_val = chip->reg_pupd_sel | (1u << off);
+		break;
+	case GPIOF_DRIVE_PULLDOWN:
+		pupd_en_reg_val = chip->reg_pupd_en | (1u << off);
+		pupd_sel_reg_val = chip->reg_pupd_sel & ~(1u << off);
+		break;
+	case GPIOF_DRIVE_STRONG:
+	case GPIOF_DRIVE_HIZ:
+		pupd_en_reg_val = chip->reg_pupd_en & ~(1u << off);
+		pupd_sel_reg_val = chip->reg_pupd_sel;
+		break;
+	default:
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	if (pupd_en_reg_val != chip->reg_pupd_en) {
+		ret = pca953x_write_reg(chip, PCAL953X_PUPD_EN,
+					pupd_en_reg_val);
+		if (ret)
+			goto exit;
+		chip->reg_pupd_en = pupd_en_reg_val;
+	}
+
+	if (pupd_sel_reg_val != chip->reg_pupd_sel) {
+		ret = pca953x_write_reg(chip, PCAL953X_PUPD_SEL,
+					pupd_sel_reg_val);
+		if (ret)
+			goto exit;
+		chip->reg_pupd_sel = pupd_sel_reg_val;
+	}
+
+exit:
+	mutex_unlock(&chip->i2c_lock);
+	return ret;
+}
+
 static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 {
 	struct gpio_chip *gc;
@@ -320,6 +389,9 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 	gc->dev = &chip->client->dev;
 	gc->owner = THIS_MODULE;
 	gc->names = chip->names;
+
+	if (chip->chip_type == PCAL953X_TYPE)
+		gc->set_drive = pca953x_gpio_set_drive;
 }
 
 #ifdef CONFIG_GPIO_PCA953X_IRQ
@@ -368,6 +440,15 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
 		new_irqs &= ~(1 << level);
 	}
 
+	if (chip->chip_type == PCAL953X_TYPE) {
+		/* Enable latch on interrupt-enabled inputs */
+		pca953x_write_reg(chip, PCAL953X_IN_LATCH,
+				  chip->irq_mask);
+		/* Unmask enabled interrupts */
+		pca953x_write_reg(chip, PCAL953X_INT_MASK,
+				  ~chip->irq_mask);
+	}
+
 	mutex_unlock(&chip->irq_lock);
 }
 
@@ -412,6 +493,24 @@ static u32 pca953x_irq_pending(struct pca953x_chip *chip)
 	u32 trigger;
 	int ret, offset = 0;
 
+	if (chip->chip_type == PCAL953X_TYPE) {
+		/* Read the current interrupt status from the device */
+		ret = pca953x_read_reg(chip, PCAL953X_INT_STAT, &pending);
+		if (ret)
+			return 0;
+
+		/* Check latched inputs and clear interrupt status */
+		ret = pca953x_read_reg(chip, PCA953X_INPUT, &cur_stat);
+		if (ret)
+			return 0;
+
+		/* Apply filter for rising/falling edge selection */
+		pending &= (~cur_stat & chip->irq_trig_fall) |
+			(cur_stat & chip->irq_trig_raise);
+
+		return pending;
+	}
+
 	switch (chip->chip_type) {
 	case PCA953X_TYPE:
 		offset = PCA953X_INPUT;
@@ -468,37 +567,43 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
 			     int irq_base)
 {
 	struct i2c_client *client = chip->client;
-	int ret, offset = 0;
+	int ret = 0, offset = 0;
+	unsigned long flags;
 	u32 temporary;
 
 	if (irq_base != -1
 			&& (id->driver_data & PCA_INT)) {
 		int lvl;
 
-		switch (chip->chip_type) {
-		case PCA953X_TYPE:
-			offset = PCA953X_INPUT;
-			break;
-		case PCA957X_TYPE:
-			offset = PCA957X_IN;
-			break;
+		if (chip->chip_type != PCAL953X_TYPE) {
+			switch (chip->chip_type) {
+			case PCA953X_TYPE:
+				offset = PCA953X_INPUT;
+				break;
+			case PCA957X_TYPE:
+				offset = PCA957X_IN;
+				break;
+			}
+			ret = pca953x_read_reg(chip, offset, &temporary);
+			chip->irq_stat = temporary;
+			if (ret)
+				goto out_failed;
+
+			/*
+			 * There is no way to know which GPIO line generated the
+			 * interrupt.  We have to rely on the previous read for
+			 * this purpose.
+			 */
+			chip->irq_stat &= chip->reg_direction;
 		}
-		ret = pca953x_read_reg(chip, offset, &temporary);
-		chip->irq_stat = temporary;
-		if (ret)
-			goto out_failed;
-
-		/*
-		 * There is no way to know which GPIO line generated the
-		 * interrupt.  We have to rely on the previous read for
-		 * this purpose.
-		 */
-		chip->irq_stat &= chip->reg_direction;
 		mutex_init(&chip->irq_lock);
 
-		chip->irq_base = irq_alloc_descs(-1, irq_base, chip->gpio_chip.ngpio, -1);
-		if (chip->irq_base < 0)
+		chip->irq_base = irq_alloc_descs(-1, irq_base,
+						 chip->gpio_chip.ngpio, -1);
+		if (chip->irq_base < 0) {
+			ret = chip->irq_base;
 			goto out_failed;
+		}
 
 		chip->domain = irq_domain_add_legacy(client->dev.of_node,
 						chip->gpio_chip.ngpio,
@@ -525,10 +630,15 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
 #endif
 		}
 
+		if (chip->chip_type == PCAL953X_TYPE)
+			flags = IRQF_TRIGGER_FALLING | IRQF_ONESHOT;
+		else
+			flags = IRQF_TRIGGER_LOW | IRQF_ONESHOT;
+
 		ret = request_threaded_irq(client->irq,
 					   NULL,
 					   pca953x_irq_handler,
-					   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+					   flags,
 					   dev_name(&client->dev), chip);
 		if (ret) {
 			dev_err(&client->dev, "failed to request irq %d\n",
@@ -537,6 +647,8 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
 		}
 
 		chip->gpio_chip.to_irq = pca953x_gpio_to_irq;
+	} else {
+		chip->irq_base = -1;
 	}
 
 	return 0;
@@ -594,7 +706,8 @@ pca953x_get_alt_pdata(struct i2c_client *client, int *gpio_base, u32 *invert)
 
 	*gpio_base = -1;
 	val = of_get_property(node, "linux,gpio-base", &size);
-	WARN(val, "%s: device-tree property 'linux,gpio-base' is deprecated!", __func__);
+	WARN(val, "%s: device-tree property 'linux,gpio-base' is deprecated!",
+	     __func__);
 	if (val) {
 		if (size != sizeof(*val))
 			dev_warn(&client->dev, "%s: wrong linux,gpio-base\n",
@@ -604,7 +717,8 @@ pca953x_get_alt_pdata(struct i2c_client *client, int *gpio_base, u32 *invert)
 	}
 
 	val = of_get_property(node, "polarity", NULL);
-	WARN(val, "%s: device-tree property 'polarity' is deprecated!", __func__);
+	WARN(val, "%s: device-tree property 'polarity' is deprecated!",
+	     __func__);
 	if (val)
 		*invert = *val;
 }
@@ -620,6 +734,18 @@ static int device_pca953x_init(struct pca953x_chip *chip, u32 invert)
 {
 	int ret;
 
+	if (chip->chip_type == PCAL953X_TYPE) {
+		ret = pca953x_read_reg(chip, PCAL953X_PUPD_EN,
+				       &chip->reg_pupd_en);
+		if (ret)
+			goto out;
+
+		ret = pca953x_read_reg(chip, PCAL953X_PUPD_SEL,
+				       &chip->reg_pupd_sel);
+		if (ret)
+			goto out;
+	}
+
 	ret = pca953x_read_reg(chip, PCA953X_OUTPUT, &chip->reg_output);
 	if (ret)
 		goto out;
@@ -688,15 +814,18 @@ static int pca953x_probe(struct i2c_client *client,
 	} else {
 		pca953x_get_alt_pdata(client, &chip->gpio_start, &invert);
 #ifdef CONFIG_OF_GPIO
-		/* If I2C node has no interrupts property, disable GPIO interrupts */
-		if (of_find_property(client->dev.of_node, "interrupts", NULL) == NULL)
+		/* If I2C node has no interrupts property, disable
+		 * GPIO interrupts */
+		if (of_find_property(client->dev.of_node,
+				     "interrupts", NULL) == NULL)
 			irq_base = -1;
 #endif
 	}
 
 	chip->client = client;
 
-	chip->chip_type = id->driver_data & (PCA953X_TYPE | PCA957X_TYPE);
+	chip->chip_type = id->driver_data &
+		(PCAL953X_TYPE | PCA953X_TYPE | PCA957X_TYPE);
 
 	mutex_init(&chip->i2c_lock);
 
@@ -705,7 +834,7 @@ static int pca953x_probe(struct i2c_client *client,
 	 */
 	pca953x_setup_gpio(chip, id->driver_data & PCA_GPIO_MASK);
 
-	if (chip->chip_type == PCA953X_TYPE)
+	if (chip->chip_type & (PCA953X_TYPE | PCAL953X_TYPE))
 		ret = device_pca953x_init(chip, invert);
 	else
 		ret = device_pca957x_init(chip, invert);
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5359ca7..5e897ff 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -60,11 +60,17 @@ struct gpio_desc {
 #define FLAG_ACTIVE_LOW	7	/* sysfs value has active low */
 #define FLAG_OPEN_DRAIN	8	/* Gpio is open drain type */
 #define FLAG_OPEN_SOURCE 9	/* Gpio is open source type */
+#define FLAG_PULLUP	10	/* Gpio drive is resistive pullup */
+#define FLAG_PULLDOWN	11	/* Gpio drive is resistive pulldown */
+#define FLAG_STRONG	12	/* Gpio drive is strong (fast output) */
+#define FLAG_HIZ	13	/* Gpio drive is Hi-Z (input) */
 
 #define ID_SHIFT	16	/* add new flags before this one */
 
 #define GPIO_FLAGS_MASK		((1 << ID_SHIFT) - 1)
 #define GPIO_TRIGGER_MASK	(BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
+#define GPIO_DRIVE_MASK		(BIT(FLAG_PULLUP) | BIT(FLAG_PULLDOWN)	\
+				| BIT(FLAG_STRONG) | BIT(FLAG_HIZ))
 
 #ifdef CONFIG_DEBUG_FS
 	const char		*label;
@@ -243,6 +249,10 @@ static DEFINE_MUTEX(sysfs_lock);
  *      * is read/write as zero/nonzero
  *      * also affects existing and subsequent "falling" and "rising"
  *        /edge configuration
+ *   /drive
+ *      * sets signal drive mode
+ *      * is read/write as "pullup", "pulldown", "strong" or "hiz"
+ *
  */
 
 static ssize_t gpio_direction_show(struct device *dev,
@@ -573,9 +583,85 @@ static ssize_t gpio_active_low_store(struct device *dev,
 static const DEVICE_ATTR(active_low, 0644,
 		gpio_active_low_show, gpio_active_low_store);
 
+static ssize_t gpio_drive_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	const struct gpio_desc	*desc = dev_get_drvdata(dev);
+	ssize_t			status;
+
+	mutex_lock(&sysfs_lock);
+
+	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
+		status = -EIO;
+	} else {
+		if (test_bit(FLAG_PULLUP, &desc->flags))
+			status = sprintf(buf, "pullup\n");
+		else if (test_bit(FLAG_PULLDOWN, &desc->flags))
+			status = sprintf(buf, "pulldown\n");
+		else if (test_bit(FLAG_STRONG, &desc->flags))
+			status = sprintf(buf, "strong\n");
+		else if (test_bit(FLAG_HIZ, &desc->flags))
+			status = sprintf(buf, "hiz\n");
+		else
+			status = -EINVAL;
+	}
+
+	mutex_unlock(&sysfs_lock);
+	return status;
+}
+
+static ssize_t gpio_drive_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct gpio_desc	*desc = dev_get_drvdata(dev);
+	unsigned		gpio = desc - gpio_desc;
+	ssize_t			status;
+
+	mutex_lock(&sysfs_lock);
+
+	if (!test_bit(FLAG_EXPORT, &desc->flags))
+		status = -EIO;
+	else {
+		if (sysfs_streq(buf, "pullup")) {
+			status = gpio_set_drive(gpio, GPIOF_DRIVE_PULLUP);
+			if (!status) {
+				desc->flags &= ~GPIO_DRIVE_MASK;
+				set_bit(FLAG_PULLUP, &desc->flags);
+			}
+		} else if (sysfs_streq(buf, "pulldown")) {
+			status = gpio_set_drive(gpio, GPIOF_DRIVE_PULLDOWN);
+			if (!status) {
+				desc->flags &= ~GPIO_DRIVE_MASK;
+				set_bit(FLAG_PULLDOWN, &desc->flags);
+			}
+		} else if (sysfs_streq(buf, "strong")) {
+			status = gpio_set_drive(gpio, GPIOF_DRIVE_STRONG);
+			if (!status) {
+				desc->flags &= ~GPIO_DRIVE_MASK;
+				set_bit(FLAG_STRONG, &desc->flags);
+			}
+		} else if (sysfs_streq(buf, "hiz")) {
+			status = gpio_set_drive(gpio, GPIOF_DRIVE_HIZ);
+			if (!status) {
+				desc->flags &= ~GPIO_DRIVE_MASK;
+				set_bit(FLAG_HIZ, &desc->flags);
+			}
+		} else {
+			status = -EINVAL;
+		}
+	}
+
+	mutex_unlock(&sysfs_lock);
+	return status ? : size;
+}
+
+static const DEVICE_ATTR(drive, 0644,
+		gpio_drive_show, gpio_drive_store);
+
 static const struct attribute *gpio_attrs[] = {
 	&dev_attr_value.attr,
 	&dev_attr_active_low.attr,
+	&dev_attr_drive.attr,
 	NULL,
 };
 
@@ -1677,6 +1763,50 @@ fail:
 }
 EXPORT_SYMBOL_GPL(gpio_set_debounce);
 
+/**
+ * gpio_set_drive - sets drive @mode for a @gpio
+ * @gpio: the gpio to set the drive mode
+ * @mode: the drive mode
+ */
+int gpio_set_drive(unsigned gpio, unsigned mode)
+{
+	unsigned long		flags;
+	struct gpio_chip	*chip;
+	struct gpio_desc	*desc = &gpio_desc[gpio];
+	int			status = -EINVAL;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (!gpio_is_valid(gpio))
+		goto fail;
+	chip = desc->chip;
+	if (!chip || !chip->set || !chip->set_drive)
+		goto fail;
+	gpio -= chip->base;
+	if (gpio >= chip->ngpio)
+		goto fail;
+	status = gpio_ensure_requested(desc, gpio);
+	if (status < 0)
+		goto fail;
+
+	/* now we know the gpio is valid and chip won't vanish */
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	might_sleep_if(chip->can_sleep);
+
+	return chip->set_drive(chip, gpio, mode);
+
+fail:
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	if (status)
+		pr_debug("%s: gpio-%d status %d\n",
+			__func__, gpio, status);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_set_drive);
+
 /* I/O calls are only valid after configuration completed; the relevant
  * "is this a valid GPIO" error checks should already have been done.
  *
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 20ca766..8265ccc 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -65,6 +65,7 @@ struct device_node;
  * @direction_output: configures signal "offset" as output, or returns error
  * @set_debounce: optional hook for setting debounce time for specified gpio in
  *      interrupt triggered gpio chips
+ * @set_drive: optional hook for setting the drive signal for "offset"
  * @set: assigns output value for signal "offset"
  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  *	implementation may not sleep
@@ -113,6 +114,8 @@ struct gpio_chip {
 						unsigned offset, int value);
 	int			(*set_debounce)(struct gpio_chip *chip,
 						unsigned offset, unsigned debounce);
+	int			(*set_drive)(struct gpio_chip *chip,
+					     unsigned offset, unsigned mode);
 
 	void			(*set)(struct gpio_chip *chip,
 						unsigned offset, int value);
@@ -172,6 +175,7 @@ extern int gpio_direction_input(unsigned gpio);
 extern int gpio_direction_output(unsigned gpio, int value);
 
 extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
+extern int gpio_set_drive(unsigned gpio, unsigned mode);
 
 extern int gpio_get_value_cansleep(unsigned gpio);
 extern void gpio_set_value_cansleep(unsigned gpio, int value);
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index bfe6656..cadd9d2 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h
@@ -27,6 +27,11 @@
 #define GPIOF_EXPORT_DIR_FIXED	(GPIOF_EXPORT)
 #define GPIOF_EXPORT_DIR_CHANGEABLE (GPIOF_EXPORT | GPIOF_EXPORT_CHANGEABLE)
 
+#define GPIOF_DRIVE_PULLUP	(1 << 6)
+#define GPIOF_DRIVE_PULLDOWN	(1 << 7)
+#define GPIOF_DRIVE_STRONG	(1 << 8)
+#define GPIOF_DRIVE_HIZ		(1 << 9)
+
 /**
  * struct gpio - a structure describing a GPIO with configuration
  * @gpio:	the GPIO number
@@ -156,6 +161,11 @@ static inline int gpio_set_debounce(unsigned gpio, unsigned debounce)
 	return -ENOSYS;
 }
 
+static inline int gpio_set_drive(unsigned gpio, unsigned mode)
+{
+	return -ENOSYS;
+}
+
 static inline int gpio_get_value(unsigned gpio)
 {
 	/* GPIO can never have been requested or set as {in,out}put */