viafb: add a driver for GPIO lines

This is a simple gpiolib driver giving access to the GPIO lines in the
VIA framebuffer system.  A simple mechanism exists for switching lines
between GPIO and I2C, but it's only compile-time for now.

Cc: ScottFang@viatech.com.cn
Cc: JosephChan@via.com.tw
Cc: Harald Welte <laforge@gnumonks.org>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 268 insertions, 0 deletions

diff --git a/drivers/video/via/via-gpio.c b/drivers/video/via/via-gpio.c
new file mode 100644
index 0000000..e119d21
--- /dev/null
+++ b/drivers/video/via/via-gpio.c
@@ -0,0 +1,268 @@
+/*
+ * Support for viafb GPIO ports.
+ *
+ * Copyright 2009 Jonathan Corbet <corbet@lwn.net>
+ * Distributable under version 2 of the GNU General Public License.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/gpio.h>
+#include "via-core.h"
+#include "via-gpio.h"
+#include "global.h"
+
+/*
+ * The ports we know about.  Note that the port-25 gpios are not
+ * mentioned in the datasheet.
+ */
+
+struct viafb_gpio {
+	char *vg_name;	/* Data sheet name */
+	u16 vg_io_port;
+	u8  vg_port_index;
+	int  vg_mask_shift;
+};
+
+static struct viafb_gpio viafb_all_gpios[] = {
+	{
+		.vg_name = "VGPIO0",  /* Guess - not in datasheet */
+		.vg_io_port = VIASR,
+		.vg_port_index = 0x25,
+		.vg_mask_shift = 1
+	},
+	{
+		.vg_name = "VGPIO1",
+		.vg_io_port = VIASR,
+		.vg_port_index = 0x25,
+		.vg_mask_shift = 0
+	},
+	{
+		.vg_name = "VGPIO2",  /* aka DISPCLKI0 */
+		.vg_io_port = VIASR,
+		.vg_port_index = 0x2c,
+		.vg_mask_shift = 1
+	},
+	{
+		.vg_name = "VGPIO3",  /* aka DISPCLKO0 */
+		.vg_io_port = VIASR,
+		.vg_port_index = 0x2c,
+		.vg_mask_shift = 0
+	},
+	{
+		.vg_name = "VGPIO4",  /* DISPCLKI1 */
+		.vg_io_port = VIASR,
+		.vg_port_index = 0x3d,
+		.vg_mask_shift = 1
+	},
+	{
+		.vg_name = "VGPIO5",  /* DISPCLKO1 */
+		.vg_io_port = VIASR,
+		.vg_port_index = 0x3d,
+		.vg_mask_shift = 0
+	},
+};
+
+#define VIAFB_NUM_GPIOS ARRAY_SIZE(viafb_all_gpios)
+
+/*
+ * This structure controls the active GPIOs, which may be a subset
+ * of those which are known.
+ */
+
+struct viafb_gpio_cfg {
+	struct gpio_chip gpio_chip;
+	struct viafb_dev *vdev;
+	struct viafb_gpio *active_gpios[VIAFB_NUM_GPIOS];
+	char *gpio_names[VIAFB_NUM_GPIOS];
+};
+
+/*
+ * GPIO access functions
+ */
+static void via_gpio_set(struct gpio_chip *chip, unsigned int nr,
+			 int value)
+{
+	struct viafb_gpio_cfg *cfg = container_of(chip,
+						  struct viafb_gpio_cfg,
+						  gpio_chip);
+	u8 reg;
+	struct viafb_gpio *gpio;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cfg->vdev->reg_lock, flags);
+	gpio = cfg->active_gpios[nr];
+	reg = viafb_read_reg(VIASR, gpio->vg_port_index);
+	reg |= 0x40 << gpio->vg_mask_shift;  /* output enable */
+	if (value)
+		reg |= 0x10 << gpio->vg_mask_shift;
+	else
+		reg &= ~(0x10 << gpio->vg_mask_shift);
+	viafb_write_reg(gpio->vg_port_index, VIASR, reg);
+	spin_unlock_irqrestore(&cfg->vdev->reg_lock, flags);
+}
+
+static int via_gpio_dir_out(struct gpio_chip *chip, unsigned int nr,
+			    int value)
+{
+	via_gpio_set(chip, nr, value);
+	return 0;
+}
+
+/*
+ * Set the input direction.  I'm not sure this is right; we should
+ * be able to do input without disabling output.
+ */
+static int via_gpio_dir_input(struct gpio_chip *chip, unsigned int nr)
+{
+	struct viafb_gpio_cfg *cfg = container_of(chip,
+						  struct viafb_gpio_cfg,
+						  gpio_chip);
+	struct viafb_gpio *gpio;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cfg->vdev->reg_lock, flags);
+	gpio = cfg->active_gpios[nr];
+	viafb_write_reg_mask(gpio->vg_port_index, VIASR, 0,
+			     0x40 << gpio->vg_mask_shift);
+	spin_unlock_irqrestore(&cfg->vdev->reg_lock, flags);
+	return 0;
+}
+
+static int via_gpio_get(struct gpio_chip *chip, unsigned int nr)
+{
+	struct viafb_gpio_cfg *cfg = container_of(chip,
+						  struct viafb_gpio_cfg,
+						  gpio_chip);
+	u8 reg;
+	struct viafb_gpio *gpio;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cfg->vdev->reg_lock, flags);
+	gpio = cfg->active_gpios[nr];
+	reg = viafb_read_reg(VIASR, gpio->vg_port_index);
+	spin_unlock_irqrestore(&cfg->vdev->reg_lock, flags);
+	return reg & (0x04 << gpio->vg_mask_shift);
+}
+
+
+static struct viafb_gpio_cfg gpio_config = {
+	.gpio_chip = {
+		.label = "VIAFB onboard GPIO",
+		.owner = THIS_MODULE,
+		.direction_output = via_gpio_dir_out,
+		.set = via_gpio_set,
+		.direction_input = via_gpio_dir_input,
+		.get = via_gpio_get,
+		.base = -1,
+		.ngpio = 0,
+		.can_sleep = 0
+	}
+};
+
+/*
+ * Manage the software enable bit.
+ */
+static void viafb_gpio_enable(struct viafb_gpio *gpio)
+{
+	viafb_write_reg_mask(gpio->vg_port_index, VIASR, 0x02, 0x02);
+}
+
+static void viafb_gpio_disable(struct viafb_gpio *gpio)
+{
+	viafb_write_reg_mask(gpio->vg_port_index, VIASR, 0, 0x02);
+}
+
+
+
+
+int viafb_create_gpios(struct viafb_dev *vdev,
+		const struct via_port_cfg *port_cfg)
+{
+	int i, ngpio = 0, ret;
+	struct viafb_gpio *gpio;
+	unsigned long flags;
+
+	/*
+	 * Set up entries for all GPIOs which have been configured to
+	 * operate as such (as opposed to as i2c ports).
+	 */
+	for (i = 0; i < VIAFB_NUM_PORTS; i++) {
+		if (port_cfg[i].mode != VIA_MODE_GPIO)
+			continue;
+		for (gpio = viafb_all_gpios;
+		     gpio < viafb_all_gpios + VIAFB_NUM_GPIOS; gpio++)
+			if (gpio->vg_port_index == port_cfg[i].ioport_index) {
+				gpio_config.active_gpios[ngpio] = gpio;
+				gpio_config.gpio_names[ngpio] = gpio->vg_name;
+				ngpio++;
+			}
+	}
+	gpio_config.gpio_chip.ngpio = ngpio;
+	gpio_config.gpio_chip.names = gpio_config.gpio_names;
+	gpio_config.vdev = vdev;
+	if (ngpio == 0) {
+		printk(KERN_INFO "viafb: no GPIOs configured\n");
+		return 0;
+	}
+	/*
+	 * Enable the ports.  They come in pairs, with a single
+	 * enable bit for both.
+	 */
+	spin_lock_irqsave(&gpio_config.vdev->reg_lock, flags);
+	for (i = 0; i < ngpio; i += 2)
+		viafb_gpio_enable(gpio_config.active_gpios[i]);
+	spin_unlock_irqrestore(&gpio_config.vdev->reg_lock, flags);
+	/*
+	 * Get registered.
+	 */
+	gpio_config.gpio_chip.base = -1;  /* Dynamic */
+	ret = gpiochip_add(&gpio_config.gpio_chip);
+	if (ret) {
+		printk(KERN_ERR "viafb: failed to add gpios (%d)\n", ret);
+		gpio_config.gpio_chip.ngpio = 0;
+	}
+	return ret;
+/* Port enable ? */
+}
+
+
+int viafb_destroy_gpios(void)
+{
+	unsigned long flags;
+	int ret = 0, i;
+
+	spin_lock_irqsave(&gpio_config.vdev->reg_lock, flags);
+	/*
+	 * Get unregistered.
+	 */
+	if (gpio_config.gpio_chip.ngpio > 0) {
+		ret = gpiochip_remove(&gpio_config.gpio_chip);
+		if (ret) { /* Somebody still using it? */
+			printk(KERN_ERR "Viafb: GPIO remove failed\n");
+			goto out;
+		}
+	}
+	/*
+	 * Disable the ports.
+	 */
+	for (i = 0; i < gpio_config.gpio_chip.ngpio; i += 2)
+		viafb_gpio_disable(gpio_config.active_gpios[i]);
+	gpio_config.gpio_chip.ngpio = 0;
+out:
+	spin_unlock_irqrestore(&gpio_config.vdev->reg_lock, flags);
+	return ret;
+}
+
+/*
+ * Look up a specific gpio and return the number it was assigned.
+ */
+int viafb_gpio_lookup(const char *name)
+{
+	int i;
+
+	for (i = 0; i < gpio_config.gpio_chip.ngpio; i++)
+		if (!strcmp(name, gpio_config.active_gpios[i]->vg_name))
+			return gpio_config.gpio_chip.base + i;
+	return -1;
+}
+EXPORT_SYMBOL_GPL(viafb_gpio_lookup);