gpio.zip_PCA9557_pca953x

#include <linux/kernel.h> #include <linux/module.h> #include <linux/irq.h> #include <linux/spinlock.h> #include <linux/device.h> #include <linux/err.h> #include <linux/debugfs.h> #include <linux/seq_file.h> #include <linux/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 #define FLAG_RESERVED 2 #define FLAG_EXPORT 3 /* protected by sysfs_lock */ #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */ #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... so should * the weaker cleanup after faults, compared to gpio_request(). * * NOTE: the autorequest mechanism is going away; at this point it's * only "legal" in the sense that (old) code using it won't break yet, * but instead only triggers a WARN() stack dump. */ static int gpio_ensure_requested(struct gpio_desc *desc, unsigned offset) { const struct gpio_chip *chip = desc->chip; const int gpio = chip->base + offset; if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0, "autorequest GPIO-%d\n", gpio)) { if (!try_module_get(chip->owner)) { pr_err("GPIO-%d: module can't be gotten \n", gpio); clear_bit(FLAG_REQUESTED, &desc->flags); /* lose */ return -EIO; } desc_set_label(desc, "[auto]"); /* caller must chip->request() w/o spinlock */ if (chip->request) return 1; } return 0; } /* 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; } /* dynamic allocation of GPIOs, e.g. on a hotplugged device */ static int gpiochip_find_base(int ngpio) { int i; int spare = 0; int base = -ENOSPC; for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) { struct gpio_desc *desc = &gpio_desc[i]; struct gpio_chip *chip = desc->chip; if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) { spare++; if (spare == ngpio) { base = i; break; } } else { spare = 0; if (chip) i -= chip->ngpio - 1; } } if (gpio_is_valid(base)) pr_debug("%s: found new base at %d\n", __func__, base); return base; } /** * gpiochip_reserve() - reserve range of gpios to use with platform code only * @start: starting gpio number * @ngpio: number of gpios to reserve * Context: platform init, potentially before irqs or kmalloc will work * * Returns a negative errno if any gpio within the range is already reserved * or registered, else returns zero as a success code. Use this function * to mark a range of gpios as unavailable for dynamic gpio number allocation, * for example because its driver support is not yet loaded. */ int __init gpiochip_reserve(int start, int ngpio) { int ret = 0; unsigned long flags; int i; if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1)) return -EINVAL; spin_lock_irqsave(&gpio_lock, flags); for (i = start; i < start + ngpio; i++) { struct gpio_desc *desc = &gpio_desc[i]; if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) { ret = -EBUSY; goto err; } set_bit(FLAG_RESERVED, &desc->flags); } pr_debug("%s: reserved gpios from %d to %d\n", __func__, start, start + ngpio - 1); err: spin_unlock_irqrestore(&gpio_lock, flags); return ret; } #ifdef CONFIG_GPIO_SYSFS /* lock protects against unexport_gpio() being called while * sysfs files are active. */ static DEFINE_MUTEX(sysfs_lock); /* * /sys/class/gpio/gpioN... only for GPIOs that are exported * /direction * * MAY BE OMITTED if kernel won't allow direction changes * * is read/write as "in" or "out" * * may also be written as "high" or "low", initializing * output value as specified ("out" implies "low") * /value * * always readable, subject to hardware behavior * * may be writable, as zero/nonzero * * REVISIT there will likely be an attribute for configuring async * notifications, e.g. to specify polling interval or IRQ trigger type * that would for example trigger a poll() on the "value". */ static ssize_t gpio_direction_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 status = sprintf(buf, "%s\n", test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in"); mutex_unlock(&sysfs_lock); return status; } static ssize_t gpio_direction_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { const 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, "high")) status = gpio_direction_output(gpio, 1); else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low")) status = gpio_direction_output(gpio, 0); else if (sysfs_streq(buf, "in")) status = gpio_direction_input(gpio); else status = -EINVAL; mutex_unlock(&sysfs_lock); return status ? : size; } static const DEVICE_ATTR(direction, 0644, gpio_direction_show, gpio_direction_store); static ssize_t gpio_value_show(struct device *dev, struct device_attribute *attr, char *buf) { const 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 status = sprintf(buf, "%d\n", !!gpio_get_value_cansleep(gpio)); mutex_unlock(&sysfs_lock); return status; } static ssize_t gpio_value_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { const 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 (!test_bit(FLAG_IS_OUT, &desc->flags)) status = -EPERM; else { long value; status = strict_strtol(buf, 0, &value); if (status == 0) { gpio_set_value_cansleep(gpio, value != 0); status = size; } } mutex_unlock(&sysfs_lock); return status; } static /*const*/ DEVICE_ATTR(value, 0644, gpio_value_show, gpio_value_store); static const struct attribute *gpio_attrs[] = { &dev_attr_direction.attr, &dev_attr_value.attr,