Input: Generic GPIO Input device.

Supports keyboard matrixces, direct inputs, direct outputs and axes connected to gpios.

Change-Id: I5e921e6e3a1cc169316ee3b665f4cc21b5735114
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Nick Pelly <npelly@google.com>

1 files changed, 376 insertions, 0 deletions

diff --git a/drivers/input/misc/gpio_input.c b/drivers/input/misc/gpio_input.c
new file mode 100644
index 00000000000..6a0c3151096
--- /dev/null
+++ b/drivers/input/misc/gpio_input.c
@@ -0,0 +1,376 @@
+/* drivers/input/misc/gpio_input.c
+ *
+ * Copyright (C) 2007 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/gpio.h>
+#include <linux/gpio_event.h>
+#include <linux/hrtimer.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/wakelock.h>
+
+enum {
+	DEBOUNCE_UNSTABLE     = BIT(0),	/* Got irq, while debouncing */
+	DEBOUNCE_PRESSED      = BIT(1),
+	DEBOUNCE_NOTPRESSED   = BIT(2),
+	DEBOUNCE_WAIT_IRQ     = BIT(3),	/* Stable irq state */
+	DEBOUNCE_POLL         = BIT(4),	/* Stable polling state */
+
+	DEBOUNCE_UNKNOWN =
+		DEBOUNCE_PRESSED | DEBOUNCE_NOTPRESSED,
+};
+
+struct gpio_key_state {
+	struct gpio_input_state *ds;
+	uint8_t debounce;
+};
+
+struct gpio_input_state {
+	struct gpio_event_input_devs *input_devs;
+	const struct gpio_event_input_info *info;
+	struct hrtimer timer;
+	int use_irq;
+	int debounce_count;
+	spinlock_t irq_lock;
+	struct wake_lock wake_lock;
+	struct gpio_key_state key_state[0];
+};
+
+static enum hrtimer_restart gpio_event_input_timer_func(struct hrtimer *timer)
+{
+	int i;
+	int pressed;
+	struct gpio_input_state *ds =
+		container_of(timer, struct gpio_input_state, timer);
+	unsigned gpio_flags = ds->info->flags;
+	unsigned npolarity;
+	int nkeys = ds->info->keymap_size;
+	const struct gpio_event_direct_entry *key_entry;
+	struct gpio_key_state *key_state;
+	unsigned long irqflags;
+	uint8_t debounce;
+	bool sync_needed;
+
+#if 0
+	key_entry = kp->keys_info->keymap;
+	key_state = kp->key_state;
+	for (i = 0; i < nkeys; i++, key_entry++, key_state++)
+		pr_info("gpio_read_detect_status %d %d\n", key_entry->gpio,
+			gpio_read_detect_status(key_entry->gpio));
+#endif
+	key_entry = ds->info->keymap;
+	key_state = ds->key_state;
+	sync_needed = false;
+	spin_lock_irqsave(&ds->irq_lock, irqflags);
+	for (i = 0; i < nkeys; i++, key_entry++, key_state++) {
+		debounce = key_state->debounce;
+		if (debounce & DEBOUNCE_WAIT_IRQ)
+			continue;
+		if (key_state->debounce & DEBOUNCE_UNSTABLE) {
+			debounce = key_state->debounce = DEBOUNCE_UNKNOWN;
+			enable_irq(gpio_to_irq(key_entry->gpio));
+			if (gpio_flags & GPIOEDF_PRINT_KEY_UNSTABLE)
+				pr_info("gpio_keys_scan_keys: key %x-%x, %d "
+					"(%d) continue debounce\n",
+					ds->info->type, key_entry->code,
+					i, key_entry->gpio);
+		}
+		npolarity = !(gpio_flags & GPIOEDF_ACTIVE_HIGH);
+		pressed = gpio_get_value(key_entry->gpio) ^ npolarity;
+		if (debounce & DEBOUNCE_POLL) {
+			if (pressed == !(debounce & DEBOUNCE_PRESSED)) {
+				ds->debounce_count++;
+				key_state->debounce = DEBOUNCE_UNKNOWN;
+				if (gpio_flags & GPIOEDF_PRINT_KEY_DEBOUNCE)
+					pr_info("gpio_keys_scan_keys: key %x-"
+						"%x, %d (%d) start debounce\n",
+						ds->info->type, key_entry->code,
+						i, key_entry->gpio);
+			}
+			continue;
+		}
+		if (pressed && (debounce & DEBOUNCE_NOTPRESSED)) {
+			if (gpio_flags & GPIOEDF_PRINT_KEY_DEBOUNCE)
+				pr_info("gpio_keys_scan_keys: key %x-%x, %d "
+					"(%d) debounce pressed 1\n",
+					ds->info->type, key_entry->code,
+					i, key_entry->gpio);
+			key_state->debounce = DEBOUNCE_PRESSED;
+			continue;
+		}
+		if (!pressed && (debounce & DEBOUNCE_PRESSED)) {
+			if (gpio_flags & GPIOEDF_PRINT_KEY_DEBOUNCE)
+				pr_info("gpio_keys_scan_keys: key %x-%x, %d "
+					"(%d) debounce pressed 0\n",
+					ds->info->type, key_entry->code,
+					i, key_entry->gpio);
+			key_state->debounce = DEBOUNCE_NOTPRESSED;
+			continue;
+		}
+		/* key is stable */
+		ds->debounce_count--;
+		if (ds->use_irq)
+			key_state->debounce |= DEBOUNCE_WAIT_IRQ;
+		else
+			key_state->debounce |= DEBOUNCE_POLL;
+		if (gpio_flags & GPIOEDF_PRINT_KEYS)
+			pr_info("gpio_keys_scan_keys: key %x-%x, %d (%d) "
+				"changed to %d\n", ds->info->type,
+				key_entry->code, i, key_entry->gpio, pressed);
+		input_event(ds->input_devs->dev[key_entry->dev], ds->info->type,
+			    key_entry->code, pressed);
+		sync_needed = true;
+	}
+	if (sync_needed) {
+		for (i = 0; i < ds->input_devs->count; i++)
+			input_sync(ds->input_devs->dev[i]);
+	}
+
+#if 0
+	key_entry = kp->keys_info->keymap;
+	key_state = kp->key_state;
+	for (i = 0; i < nkeys; i++, key_entry++, key_state++) {
+		pr_info("gpio_read_detect_status %d %d\n", key_entry->gpio,
+			gpio_read_detect_status(key_entry->gpio));
+	}
+#endif
+
+	if (ds->debounce_count)
+		hrtimer_start(timer, ds->info->debounce_time, HRTIMER_MODE_REL);
+	else if (!ds->use_irq)
+		hrtimer_start(timer, ds->info->poll_time, HRTIMER_MODE_REL);
+	else
+		wake_unlock(&ds->wake_lock);
+
+	spin_unlock_irqrestore(&ds->irq_lock, irqflags);
+
+	return HRTIMER_NORESTART;
+}
+
+static irqreturn_t gpio_event_input_irq_handler(int irq, void *dev_id)
+{
+	struct gpio_key_state *ks = dev_id;
+	struct gpio_input_state *ds = ks->ds;
+	int keymap_index = ks - ds->key_state;
+	const struct gpio_event_direct_entry *key_entry;
+	unsigned long irqflags;
+	int pressed;
+
+	if (!ds->use_irq)
+		return IRQ_HANDLED;
+
+	key_entry = &ds->info->keymap[keymap_index];
+
+	if (ds->info->debounce_time.tv64) {
+		spin_lock_irqsave(&ds->irq_lock, irqflags);
+		if (ks->debounce & DEBOUNCE_WAIT_IRQ) {
+			ks->debounce = DEBOUNCE_UNKNOWN;
+			if (ds->debounce_count++ == 0) {
+				wake_lock(&ds->wake_lock);
+				hrtimer_start(
+					&ds->timer, ds->info->debounce_time,
+					HRTIMER_MODE_REL);
+			}
+			if (ds->info->flags & GPIOEDF_PRINT_KEY_DEBOUNCE)
+				pr_info("gpio_event_input_irq_handler: "
+					"key %x-%x, %d (%d) start debounce\n",
+					ds->info->type, key_entry->code,
+					keymap_index, key_entry->gpio);
+		} else {
+			disable_irq_nosync(irq);
+			ks->debounce = DEBOUNCE_UNSTABLE;
+		}
+		spin_unlock_irqrestore(&ds->irq_lock, irqflags);
+	} else {
+		pressed = gpio_get_value(key_entry->gpio) ^
+			!(ds->info->flags & GPIOEDF_ACTIVE_HIGH);
+		if (ds->info->flags & GPIOEDF_PRINT_KEYS)
+			pr_info("gpio_event_input_irq_handler: key %x-%x, %d "
+				"(%d) changed to %d\n",
+				ds->info->type, key_entry->code, keymap_index,
+				key_entry->gpio, pressed);
+		input_event(ds->input_devs->dev[key_entry->dev], ds->info->type,
+			    key_entry->code, pressed);
+		input_sync(ds->input_devs->dev[key_entry->dev]);
+	}
+	return IRQ_HANDLED;
+}
+
+static int gpio_event_input_request_irqs(struct gpio_input_state *ds)
+{
+	int i;
+	int err;
+	unsigned int irq;
+	unsigned long req_flags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
+
+	for (i = 0; i < ds->info->keymap_size; i++) {
+		err = irq = gpio_to_irq(ds->info->keymap[i].gpio);
+		if (err < 0)
+			goto err_gpio_get_irq_num_failed;
+		err = request_irq(irq, gpio_event_input_irq_handler,
+				  req_flags, "gpio_keys", &ds->key_state[i]);
+		if (err) {
+			pr_err("gpio_event_input_request_irqs: request_irq "
+				"failed for input %d, irq %d\n",
+				ds->info->keymap[i].gpio, irq);
+			goto err_request_irq_failed;
+		}
+		if (ds->info->info.no_suspend) {
+			err = enable_irq_wake(irq);
+			if (err) {
+				pr_err("gpio_event_input_request_irqs: "
+					"enable_irq_wake failed for input %d, "
+					"irq %d\n",
+					ds->info->keymap[i].gpio, irq);
+				goto err_enable_irq_wake_failed;
+			}
+		}
+	}
+	return 0;
+
+	for (i = ds->info->keymap_size - 1; i >= 0; i--) {
+		irq = gpio_to_irq(ds->info->keymap[i].gpio);
+		if (ds->info->info.no_suspend)
+			disable_irq_wake(irq);
+err_enable_irq_wake_failed:
+		free_irq(irq, &ds->key_state[i]);
+err_request_irq_failed:
+err_gpio_get_irq_num_failed:
+		;
+	}
+	return err;
+}
+
+int gpio_event_input_func(struct gpio_event_input_devs *input_devs,
+			struct gpio_event_info *info, void **data, int func)
+{
+	int ret;
+	int i;
+	unsigned long irqflags;
+	struct gpio_event_input_info *di;
+	struct gpio_input_state *ds = *data;
+
+	di = container_of(info, struct gpio_event_input_info, info);
+
+	if (func == GPIO_EVENT_FUNC_SUSPEND) {
+		if (ds->use_irq)
+			for (i = 0; i < di->keymap_size; i++)
+				disable_irq(gpio_to_irq(di->keymap[i].gpio));
+		hrtimer_cancel(&ds->timer);
+		return 0;
+	}
+	if (func == GPIO_EVENT_FUNC_RESUME) {
+		spin_lock_irqsave(&ds->irq_lock, irqflags);
+		if (ds->use_irq)
+			for (i = 0; i < di->keymap_size; i++)
+				enable_irq(gpio_to_irq(di->keymap[i].gpio));
+		hrtimer_start(&ds->timer, ktime_set(0, 0), HRTIMER_MODE_REL);
+		spin_unlock_irqrestore(&ds->irq_lock, irqflags);
+		return 0;
+	}
+
+	if (func == GPIO_EVENT_FUNC_INIT) {
+		if (ktime_to_ns(di->poll_time) <= 0)
+			di->poll_time = ktime_set(0, 20 * NSEC_PER_MSEC);
+
+		*data = ds = kzalloc(sizeof(*ds) + sizeof(ds->key_state[0]) *
+					di->keymap_size, GFP_KERNEL);
+		if (ds == NULL) {
+			ret = -ENOMEM;
+			pr_err("gpio_event_input_func: "
+				"Failed to allocate private data\n");
+			goto err_ds_alloc_failed;
+		}
+		ds->debounce_count = di->keymap_size;
+		ds->input_devs = input_devs;
+		ds->info = di;
+		wake_lock_init(&ds->wake_lock, WAKE_LOCK_SUSPEND, "gpio_input");
+		spin_lock_init(&ds->irq_lock);
+
+		for (i = 0; i < di->keymap_size; i++) {
+			int dev = di->keymap[i].dev;
+			if (dev >= input_devs->count) {
+				pr_err("gpio_event_input_func: bad device "
+					"index %d >= %d for key code %d\n",
+					dev, input_devs->count,
+					di->keymap[i].code);
+				ret = -EINVAL;
+				goto err_bad_keymap;
+			}
+			input_set_capability(input_devs->dev[dev], di->type,
+					     di->keymap[i].code);
+			ds->key_state[i].ds = ds;
+			ds->key_state[i].debounce = DEBOUNCE_UNKNOWN;
+		}
+
+		for (i = 0; i < di->keymap_size; i++) {
+			ret = gpio_request(di->keymap[i].gpio, "gpio_kp_in");
+			if (ret) {
+				pr_err("gpio_event_input_func: gpio_request "
+					"failed for %d\n", di->keymap[i].gpio);
+				goto err_gpio_request_failed;
+			}
+			ret = gpio_direction_input(di->keymap[i].gpio);
+			if (ret) {
+				pr_err("gpio_event_input_func: "
+					"gpio_direction_input failed for %d\n",
+					di->keymap[i].gpio);
+				goto err_gpio_configure_failed;
+			}
+		}
+
+		ret = gpio_event_input_request_irqs(ds);
+
+		spin_lock_irqsave(&ds->irq_lock, irqflags);
+		ds->use_irq = ret == 0;
+
+		pr_info("GPIO Input Driver: Start gpio inputs for %s%s in %s "
+			"mode\n", input_devs->dev[0]->name,
+			(input_devs->count > 1) ? "..." : "",
+			ret == 0 ? "interrupt" : "polling");
+
+		hrtimer_init(&ds->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		ds->timer.function = gpio_event_input_timer_func;
+		hrtimer_start(&ds->timer, ktime_set(0, 0), HRTIMER_MODE_REL);
+		spin_unlock_irqrestore(&ds->irq_lock, irqflags);
+		return 0;
+	}
+
+	ret = 0;
+	spin_lock_irqsave(&ds->irq_lock, irqflags);
+	hrtimer_cancel(&ds->timer);
+	if (ds->use_irq) {
+		for (i = di->keymap_size - 1; i >= 0; i--) {
+			int irq = gpio_to_irq(di->keymap[i].gpio);
+			if (ds->info->info.no_suspend)
+				disable_irq_wake(irq);
+			free_irq(irq, &ds->key_state[i]);
+		}
+	}
+	spin_unlock_irqrestore(&ds->irq_lock, irqflags);
+
+	for (i = di->keymap_size - 1; i >= 0; i--) {
+err_gpio_configure_failed:
+		gpio_free(di->keymap[i].gpio);
+err_gpio_request_failed:
+		;
+	}
+err_bad_keymap:
+	wake_lock_destroy(&ds->wake_lock);
+	kfree(ds);
+err_ds_alloc_failed:
+	return ret;
+}