--- /dev/null
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+
+#include <asm/gpio.h>
+
+
+/* Optional implementation infrastructure for GPIO interfaces.
+ *
+ * Platforms may want to use this if they tend to use very many GPIOs
+ * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
+ *
+ * When kernel footprint or instruction count is an issue, simpler
+ * implementations may be preferred. The GPIO programming interface
+ * allows for inlining speed-critical get/set operations for common
+ * cases, so that access to SOC-integrated GPIOs can sometimes cost
+ * only an instruction or two per bit.
+ */
+
+
+/* When debugging, extend minimal trust to callers and platform code.
+ * Also emit diagnostic messages that may help initial bringup, when
+ * board setup or driver bugs are most common.
+ *
+ * Otherwise, minimize overhead in what may be bitbanging codepaths.
+ */
+#ifdef DEBUG
+#define extra_checks 1
+#else
+#define extra_checks 0
+#endif
+
+/* gpio_lock prevents conflicts during gpio_desc[] table updates.
+ * While any GPIO is requested, its gpio_chip is not removable;
+ * each GPIO's "requested" flag serves as a lock and refcount.
+ */
+static DEFINE_SPINLOCK(gpio_lock);
+
+struct gpio_desc {
+ struct gpio_chip *chip;
+ unsigned long flags;
+/* flag symbols are bit numbers */
+#define FLAG_REQUESTED 0
+#define FLAG_IS_OUT 1
+
+#ifdef CONFIG_DEBUG_FS
+ const char *label;
+#endif
+};
+static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
+
+static inline void desc_set_label(struct gpio_desc *d, const char *label)
+{
+#ifdef CONFIG_DEBUG_FS
+ d->label = label;
+#endif
+}
+
+/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
+ * when setting direction, and otherwise illegal. Until board setup code
+ * and drivers use explicit requests everywhere (which won't happen when
+ * those calls have no teeth) we can't avoid autorequesting. This nag
+ * message should motivate switching to explicit requests...
+ */
+static void gpio_ensure_requested(struct gpio_desc *desc)
+{
+ if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
+ pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
+ desc_set_label(desc, "[auto]");
+ }
+}
+
+/* caller holds gpio_lock *OR* gpio is marked as requested */
+static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
+{
+ return gpio_desc[gpio].chip;
+}
+
+/**
+ * gpiochip_add() - register a gpio_chip
+ * @chip: the chip to register, with chip->base initialized
+ * Context: potentially before irqs or kmalloc will work
+ *
+ * Returns a negative errno if the chip can't be registered, such as
+ * because the chip->base is invalid or already associated with a
+ * different chip. Otherwise it returns zero as a success code.
+ */
+int gpiochip_add(struct gpio_chip *chip)
+{
+ unsigned long flags;
+ int status = 0;
+ unsigned id;
+
+ /* NOTE chip->base negative is reserved to mean a request for
+ * dynamic allocation. We don't currently support that.
+ */
+
+ if (chip->base < 0 || (chip->base + chip->ngpio) >= ARCH_NR_GPIOS) {
+ status = -EINVAL;
+ goto fail;
+ }
+
+ spin_lock_irqsave(&gpio_lock, flags);
+
+ /* these GPIO numbers must not be managed by another gpio_chip */
+ for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+ if (gpio_desc[id].chip != NULL) {
+ status = -EBUSY;
+ break;
+ }
+ }
+ if (status == 0) {
+ for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+ gpio_desc[id].chip = chip;
+ gpio_desc[id].flags = 0;
+ }
+ }
+
+ spin_unlock_irqrestore(&gpio_lock, flags);
+fail:
+ /* failures here can mean systems won't boot... */
+ if (status)
+ pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
+ chip->base, chip->base + chip->ngpio,
+ chip->label ? : "generic");
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpiochip_add);
+
+/**
+ * gpiochip_remove() - unregister a gpio_chip
+ * @chip: the chip to unregister
+ *
+ * A gpio_chip with any GPIOs still requested may not be removed.
+ */
+int gpiochip_remove(struct gpio_chip *chip)
+{
+ unsigned long flags;
+ int status = 0;
+ unsigned id;
+
+ spin_lock_irqsave(&gpio_lock, flags);
+
+ for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+ if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
+ status = -EBUSY;
+ break;
+ }
+ }
+ if (status == 0) {
+ for (id = chip->base; id < chip->base + chip->ngpio; id++)
+ gpio_desc[id].chip = NULL;
+ }
+
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpiochip_remove);
+
+
+/* These "optional" allocation calls help prevent drivers from stomping
+ * on each other, and help provide better diagnostics in debugfs.
+ * They're called even less than the "set direction" calls.
+ */
+int gpio_request(unsigned gpio, const char *label)
+{
+ struct gpio_desc *desc;
+ int status = -EINVAL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&gpio_lock, flags);
+
+ if (gpio >= ARCH_NR_GPIOS)
+ goto done;
+ desc = &gpio_desc[gpio];
+ if (desc->chip == NULL)
+ goto done;
+
+ /* NOTE: gpio_request() can be called in early boot,
+ * before IRQs are enabled.
+ */
+
+ if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
+ desc_set_label(desc, label ? : "?");
+ status = 0;
+ } else
+ status = -EBUSY;
+
+done:
+ if (status)
+ pr_debug("gpio_request: gpio-%d (%s) status %d\n",
+ gpio, label ? : "?", status);
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpio_request);
+
+void gpio_free(unsigned gpio)
+{
+ unsigned long flags;
+ struct gpio_desc *desc;
+
+ if (gpio >= ARCH_NR_GPIOS) {
+ WARN_ON(extra_checks);
+ return;
+ }
+
+ spin_lock_irqsave(&gpio_lock, flags);
+
+ desc = &gpio_desc[gpio];
+ if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags))
+ desc_set_label(desc, NULL);
+ else
+ WARN_ON(extra_checks);
+
+ spin_unlock_irqrestore(&gpio_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gpio_free);
+
+
+/**
+ * gpiochip_is_requested - return string iff signal was requested
+ * @chip: controller managing the signal
+ * @offset: of signal within controller's 0..(ngpio - 1) range
+ *
+ * Returns NULL if the GPIO is not currently requested, else a string.
+ * If debugfs support is enabled, the string returned is the label passed
+ * to gpio_request(); otherwise it is a meaningless constant.
+ *
+ * This function is for use by GPIO controller drivers. The label can
+ * help with diagnostics, and knowing that the signal is used as a GPIO
+ * can help avoid accidentally multiplexing it to another controller.
+ */
+const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
+{
+ unsigned gpio = chip->base + offset;
+
+ if (gpio >= ARCH_NR_GPIOS || gpio_desc[gpio].chip != chip)
+ return NULL;
+ if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
+ return NULL;
+#ifdef CONFIG_DEBUG_FS
+ return gpio_desc[gpio].label;
+#else
+ return "?";
+#endif
+}
+EXPORT_SYMBOL_GPL(gpiochip_is_requested);
+
+
+/* Drivers MUST set GPIO direction before making get/set calls. In
+ * some cases this is done in early boot, before IRQs are enabled.
+ *
+ * As a rule these aren't called more than once (except for drivers
+ * using the open-drain emulation idiom) so these are natural places
+ * to accumulate extra debugging checks. Note that we can't (yet)
+ * rely on gpio_request() having been called beforehand.
+ */
+
+int gpio_direction_input(unsigned gpio)
+{
+ 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 >= ARCH_NR_GPIOS)
+ goto fail;
+ chip = desc->chip;
+ if (!chip || !chip->get || !chip->direction_input)
+ goto fail;
+ gpio -= chip->base;
+ if (gpio >= chip->ngpio)
+ goto fail;
+ gpio_ensure_requested(desc);
+
+ /* now we know the gpio is valid and chip won't vanish */
+
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ might_sleep_if(extra_checks && chip->can_sleep);
+
+ status = chip->direction_input(chip, gpio);
+ if (status == 0)
+ clear_bit(FLAG_IS_OUT, &desc->flags);
+ return status;
+fail:
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ if (status)
+ pr_debug("%s: gpio-%d status %d\n",
+ __FUNCTION__, gpio, status);
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpio_direction_input);
+
+int gpio_direction_output(unsigned gpio, int value)
+{
+ 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 >= ARCH_NR_GPIOS)
+ goto fail;
+ chip = desc->chip;
+ if (!chip || !chip->set || !chip->direction_output)
+ goto fail;
+ gpio -= chip->base;
+ if (gpio >= chip->ngpio)
+ goto fail;
+ gpio_ensure_requested(desc);
+
+ /* now we know the gpio is valid and chip won't vanish */
+
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ might_sleep_if(extra_checks && chip->can_sleep);
+
+ status = chip->direction_output(chip, gpio, value);
+ if (status == 0)
+ set_bit(FLAG_IS_OUT, &desc->flags);
+ return status;
+fail:
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ if (status)
+ pr_debug("%s: gpio-%d status %d\n",
+ __FUNCTION__, gpio, status);
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpio_direction_output);
+
+
+/* I/O calls are only valid after configuration completed; the relevant
+ * "is this a valid GPIO" error checks should already have been done.
+ *
+ * "Get" operations are often inlinable as reading a pin value register,
+ * and masking the relevant bit in that register.
+ *
+ * When "set" operations are inlinable, they involve writing that mask to
+ * one register to set a low value, or a different register to set it high.
+ * Otherwise locking is needed, so there may be little value to inlining.
+ *
+ *------------------------------------------------------------------------
+ *
+ * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
+ * have requested the GPIO. That can include implicit requesting by
+ * a direction setting call. Marking a gpio as requested locks its chip
+ * in memory, guaranteeing that these table lookups need no more locking
+ * and that gpiochip_remove() will fail.
+ *
+ * REVISIT when debugging, consider adding some instrumentation to ensure
+ * that the GPIO was actually requested.
+ */
+
+/**
+ * __gpio_get_value() - return a gpio's value
+ * @gpio: gpio whose value will be returned
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_get_value().
+ * It returns the zero or nonzero value provided by the associated
+ * gpio_chip.get() method; or zero if no such method is provided.
+ */
+int __gpio_get_value(unsigned gpio)
+{
+ struct gpio_chip *chip;
+
+ chip = gpio_to_chip(gpio);
+ WARN_ON(extra_checks && chip->can_sleep);
+ return chip->get ? chip->get(chip, gpio - chip->base) : 0;
+}
+EXPORT_SYMBOL_GPL(__gpio_get_value);
+
+/**
+ * __gpio_set_value() - assign a gpio's value
+ * @gpio: gpio whose value will be assigned
+ * @value: value to assign
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_set_value().
+ * It invokes the associated gpio_chip.set() method.
+ */
+void __gpio_set_value(unsigned gpio, int value)
+{
+ struct gpio_chip *chip;
+
+ chip = gpio_to_chip(gpio);
+ WARN_ON(extra_checks && chip->can_sleep);
+ chip->set(chip, gpio - chip->base, value);
+}
+EXPORT_SYMBOL_GPL(__gpio_set_value);
+
+/**
+ * __gpio_cansleep() - report whether gpio value access will sleep
+ * @gpio: gpio in question
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_cansleep(). It
+ * returns nonzero if access reading or writing the GPIO value can sleep.
+ */
+int __gpio_cansleep(unsigned gpio)
+{
+ struct gpio_chip *chip;
+
+ /* only call this on GPIOs that are valid! */
+ chip = gpio_to_chip(gpio);
+
+ return chip->can_sleep;
+}
+EXPORT_SYMBOL_GPL(__gpio_cansleep);
+
+
+
+/* There's no value in making it easy to inline GPIO calls that may sleep.
+ * Common examples include ones connected to I2C or SPI chips.
+ */
+
+int gpio_get_value_cansleep(unsigned gpio)
+{
+ struct gpio_chip *chip;
+
+ might_sleep_if(extra_checks);
+ chip = gpio_to_chip(gpio);
+ return chip->get(chip, gpio - chip->base);
+}
+EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
+
+void gpio_set_value_cansleep(unsigned gpio, int value)
+{
+ struct gpio_chip *chip;
+
+ might_sleep_if(extra_checks);
+ chip = gpio_to_chip(gpio);
+ chip->set(chip, gpio - chip->base, value);
+}
+EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
+
+
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+
+static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
+{
+ unsigned i;
+ unsigned gpio = chip->base;
+ struct gpio_desc *gdesc = &gpio_desc[gpio];
+ int is_out;
+
+ for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
+ if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
+ continue;
+
+ is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
+ seq_printf(s, " gpio-%-3d (%-12s) %s %s",
+ gpio, gdesc->label,
+ is_out ? "out" : "in ",
+ chip->get
+ ? (chip->get(chip, i) ? "hi" : "lo")
+ : "? ");
+
+ if (!is_out) {
+ int irq = gpio_to_irq(gpio);
+ struct irq_desc *desc = irq_desc + irq;
+
+ /* This races with request_irq(), set_irq_type(),
+ * and set_irq_wake() ... but those are "rare".
+ *
+ * More significantly, trigger type flags aren't
+ * currently maintained by genirq.
+ */
+ if (irq >= 0 && desc->action) {
+ char *trigger;
+
+ switch (desc->status & IRQ_TYPE_SENSE_MASK) {
+ case IRQ_TYPE_NONE:
+ trigger = "(default)";
+ break;
+ case IRQ_TYPE_EDGE_FALLING:
+ trigger = "edge-falling";
+ break;
+ case IRQ_TYPE_EDGE_RISING:
+ trigger = "edge-rising";
+ break;
+ case IRQ_TYPE_EDGE_BOTH:
+ trigger = "edge-both";
+ break;
+ case IRQ_TYPE_LEVEL_HIGH:
+ trigger = "level-high";
+ break;
+ case IRQ_TYPE_LEVEL_LOW:
+ trigger = "level-low";
+ break;
+ default:
+ trigger = "?trigger?";
+ break;
+ }
+
+ seq_printf(s, " irq-%d %s%s",
+ irq, trigger,
+ (desc->status & IRQ_WAKEUP)
+ ? " wakeup" : "");
+ }
+ }
+
+ seq_printf(s, "\n");
+ }
+}
+
+static int gpiolib_show(struct seq_file *s, void *unused)
+{
+ struct gpio_chip *chip = NULL;
+ unsigned gpio;
+ int started = 0;
+
+ /* REVISIT this isn't locked against gpio_chip removal ... */
+
+ for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
+ if (chip == gpio_desc[gpio].chip)
+ continue;
+ chip = gpio_desc[gpio].chip;
+ if (!chip)
+ continue;
+
+ seq_printf(s, "%sGPIOs %d-%d, %s%s:\n",
+ started ? "\n" : "",
+ chip->base, chip->base + chip->ngpio - 1,
+ chip->label ? : "generic",
+ chip->can_sleep ? ", can sleep" : "");
+ started = 1;
+ if (chip->dbg_show)
+ chip->dbg_show(s, chip);
+ else
+ gpiolib_dbg_show(s, chip);
+ }
+ return 0;
+}
+
+static int gpiolib_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, gpiolib_show, NULL);
+}
+
+static struct file_operations gpiolib_operations = {
+ .open = gpiolib_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init gpiolib_debugfs_init(void)
+{
+ /* /sys/kernel/debug/gpio */
+ (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
+ NULL, NULL, &gpiolib_operations);
+ return 0;
+}
+subsys_initcall(gpiolib_debugfs_init);
+
+#endif /* DEBUG_FS */
#ifndef _ASM_GENERIC_GPIO_H
#define _ASM_GENERIC_GPIO_H
+#ifdef CONFIG_HAVE_GPIO_LIB
+
+/* Platforms may implement their GPIO interface with library code,
+ * at a small performance cost for non-inlined operations and some
+ * extra memory (for code and for per-GPIO table entries).
+ *
+ * While the GPIO programming interface defines valid GPIO numbers
+ * to be in the range 0..MAX_INT, this library restricts them to the
+ * smaller range 0..ARCH_NR_GPIOS.
+ */
+
+#ifndef ARCH_NR_GPIOS
+#define ARCH_NR_GPIOS 256
+#endif
+
+struct seq_file;
+
+/**
+ * struct gpio_chip - abstract a GPIO controller
+ * @label: for diagnostics
+ * @direction_input: configures signal "offset" as input, or returns error
+ * @get: returns value for signal "offset"; for output signals this
+ * returns either the value actually sensed, or zero
+ * @direction_output: configures signal "offset" as output, or returns error
+ * @set: assigns output value for signal "offset"
+ * @dbg_show: optional routine to show contents in debugfs; default code
+ * will be used when this is omitted, but custom code can show extra
+ * state (such as pullup/pulldown configuration).
+ * @base: identifies the first GPIO number handled by this chip; or, if
+ * negative during registration, requests dynamic ID allocation.
+ * @ngpio: the number of GPIOs handled by this controller; the last GPIO
+ * handled is (base + ngpio - 1).
+ * @can_sleep: flag must be set iff get()/set() methods sleep, as they
+ * must while accessing GPIO expander chips over I2C or SPI
+ *
+ * A gpio_chip can help platforms abstract various sources of GPIOs so
+ * they can all be accessed through a common programing interface.
+ * Example sources would be SOC controllers, FPGAs, multifunction
+ * chips, dedicated GPIO expanders, and so on.
+ *
+ * Each chip controls a number of signals, identified in method calls
+ * by "offset" values in the range 0..(@ngpio - 1). When those signals
+ * are referenced through calls like gpio_get_value(gpio), the offset
+ * is calculated by subtracting @base from the gpio number.
+ */
+struct gpio_chip {
+ char *label;
+
+ int (*direction_input)(struct gpio_chip *chip,
+ unsigned offset);
+ int (*get)(struct gpio_chip *chip,
+ unsigned offset);
+ int (*direction_output)(struct gpio_chip *chip,
+ unsigned offset, int value);
+ void (*set)(struct gpio_chip *chip,
+ unsigned offset, int value);
+ void (*dbg_show)(struct seq_file *s,
+ struct gpio_chip *chip);
+ int base;
+ u16 ngpio;
+ unsigned can_sleep:1;
+};
+
+extern const char *gpiochip_is_requested(struct gpio_chip *chip,
+ unsigned offset);
+
+/* add/remove chips */
+extern int gpiochip_add(struct gpio_chip *chip);
+extern int __must_check gpiochip_remove(struct gpio_chip *chip);
+
+
+/* Always use the library code for GPIO management calls,
+ * or when sleeping may be involved.
+ */
+extern int gpio_request(unsigned gpio, const char *label);
+extern void gpio_free(unsigned gpio);
+
+extern int gpio_direction_input(unsigned gpio);
+extern int gpio_direction_output(unsigned gpio, int value);
+
+extern int gpio_get_value_cansleep(unsigned gpio);
+extern void gpio_set_value_cansleep(unsigned gpio, int value);
+
+
+/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
+ * the GPIO is constant and refers to some always-present controller,
+ * giving direct access to chip registers and tight bitbanging loops.
+ */
+extern int __gpio_get_value(unsigned gpio);
+extern void __gpio_set_value(unsigned gpio, int value);
+
+extern int __gpio_cansleep(unsigned gpio);
+
+
+#else
+
/* platforms that don't directly support access to GPIOs through I2C, SPI,
* or other blocking infrastructure can use these wrappers.
*/
gpio_set_value(gpio, value);
}
+#endif
+
#endif /* _ASM_GENERIC_GPIO_H */
projects / linux-2.6 / commitdiff