diff options
Diffstat (limited to 'recipes/kexecboot/linux-kexecboot-2.6.24/tosa/0022-Provide-new-implementation-infrastructure-that-platf.patch')
| -rw-r--r-- | recipes/kexecboot/linux-kexecboot-2.6.24/tosa/0022-Provide-new-implementation-infrastructure-that-platf.patch | 746 |
1 files changed, 746 insertions, 0 deletions
diff --git a/recipes/kexecboot/linux-kexecboot-2.6.24/tosa/0022-Provide-new-implementation-infrastructure-that-platf.patch b/recipes/kexecboot/linux-kexecboot-2.6.24/tosa/0022-Provide-new-implementation-infrastructure-that-platf.patch new file mode 100644 index 0000000000..f39fedbbaa --- /dev/null +++ b/recipes/kexecboot/linux-kexecboot-2.6.24/tosa/0022-Provide-new-implementation-infrastructure-that-platf.patch @@ -0,0 +1,746 @@ +From 3a0251c01446f3a6763e4406ca5495102db63aa4 Mon Sep 17 00:00:00 2001 +From: David Brownell <dbrownell@users.sourceforge.net> +Date: Fri, 18 Jan 2008 00:35:20 +0300 +Subject: [PATCH 22/64] Provide new implementation infrastructure that platforms may choose to use + when implementing the GPIO programming interface. Platforms can update their + GPIO support to use this. In many cases the incremental cost to access a + non-inlined GPIO should be less than a dozen instructions, with the memory + cost being about a page (total) of extra data and code. The upside is: + + * Providing two features which were "want to have (but OK to defer)" when + GPIO interfaces were first discussed in November 2006: + + - A "struct gpio_chip" to plug in GPIOs that aren't directly supported + by SOC platforms, but come from FPGAs or other multifunction devices + using conventional device registers (like UCB-1x00 or SM501 GPIOs, + and southbridges in PCs with more open specs than usual). + + - Full support for message-based GPIO expanders, where registers are + accessed through sleeping I/O calls. Previous support for these + "cansleep" calls was just stubs. (One example: the widely used + pcf8574 I2C chips, with 8 GPIOs each.) + + * Including a non-stub implementation of the gpio_{request,free}() calls, + making those calls much more useful. The diagnostic labels are also + recorded given DEBUG_FS, so /sys/kernel/debug/gpio can show a snapshot + of all GPIOs known to this infrastructure. + +The driver programming interfaces introduced in 2.6.21 do not change at all; +this infrastructure is entirely below those covers. + +Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> +Cc: Sam Ravnborg <sam@ravnborg.org> +Cc: Jean Delvare <khali@linux-fr.org> +Cc: Eric Miao <eric.miao@marvell.com> +Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> +Cc: Philipp Zabel <philipp.zabel@gmail.com> +Cc: Russell King <rmk@arm.linux.org.uk> +Cc: Ben Gardner <bgardner@wabtec.com> +Signed-off-by: Andrew Morton <akpm@linux-foundation.org> +--- + drivers/gpio/Makefile | 2 + + drivers/gpio/gpiolib.c | 567 ++++++++++++++++++++++++++++++++++++++++++++ + include/asm-generic/gpio.h | 98 ++++++++ + 3 files changed, 667 insertions(+), 0 deletions(-) + create mode 100644 drivers/gpio/gpiolib.c + +diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile +index cdbba6b..2db28ce 100644 +--- a/drivers/gpio/Makefile ++++ b/drivers/gpio/Makefile +@@ -1,3 +1,5 @@ + # gpio support: dedicated expander chips, etc + + ccflags-$(CONFIG_DEBUG_GPIO) += -DDEBUG ++ ++obj-$(CONFIG_HAVE_GPIO_LIB) += gpiolib.o +diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c +new file mode 100644 +index 0000000..d8db2f8 +--- /dev/null ++++ b/drivers/gpio/gpiolib.c +@@ -0,0 +1,567 @@ ++#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 */ +diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h +index 2d0aab1..f29a502 100644 +--- a/include/asm-generic/gpio.h ++++ b/include/asm-generic/gpio.h +@@ -1,6 +1,102 @@ + #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. + */ +@@ -22,4 +118,6 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value) + gpio_set_value(gpio, value); + } + ++#endif ++ + #endif /* _ASM_GENERIC_GPIO_H */ +-- +1.5.3.8 + |