gpio_request 原形代碼
其原型爲 int gpio_request(unsigned gpio, const char *label) 先說說其參數,gpio則爲你要申請的哪一個管腳,label則是爲其取一個名字。其具體實現如下:
int gpio_request(unsigned gpio, const char *label)
{
struct gpio_desc *desc;//這個自己看源碼
struct gpio_chip *chip;//這個自己看源碼
int status = -EINVAL;
unsigned long flags;
spin_lock_irqsave(&gpio_lock, flags);//屏蔽中斷
if (!gpio_is_valid(gpio))//判斷是否有效,也就是參數的取值範圍判斷
goto done;
desc = &gpio_desc[gpio];
//這個是關鍵gpio_desc爲定義的一個全局的數組變量,這個函數的實值也就是,
//用gpio_desc裏面的一個變量來表示數組中的這個元素已經被申請了,而這個變量就是下面會看到的desc->flags。
chip = desc->chip;//按理說這個這個全局的gpio_desc如果沒有初始化的話,這個chip就爲空了,隨後就直接返回-EINVAL了。
if (chip == NULL)如果不爲空繼續往下走
goto done;
if (!try_module_get(chip->owner))
goto done;
/* NOTE: gpio_request() can be called in early boot,
* before IRQs are enabled, for non-sleeping (SOC) GPIOs.
*/
if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
//這裏測試並設置flags的第FLAG_REQUESTED位,如果沒有被申請就返回該位的原值0,分析到這兒,也差不多滿足了我的個人要求。
desc_set_label(desc, label ? : "?");
status = 0;
} else {
status = -EBUSY;
module_put(chip->owner);
goto done;
}
if (chip->request) {
/* chip->request may sleep */
spin_unlock_irqrestore(&gpio_lock, flags);
status = chip->request(chip, gpio - chip->base);
spin_lock_irqsave(&gpio_lock, flags);
if (status < 0) {
desc_set_label(desc, NULL);
module_put(chip->owner);
clear_bit(FLAG_REQUESTED, &desc->flags);
}
}
done:
if (status)
pr_debug("gpio_request: gpio-%d (%s) status %d\n",
gpio, label ? : "?", status);
spin_unlock_irqrestore(&gpio_lock, flags);
return status;
}
davinci 平臺:
[cpp] view plaincopy
/*
* TI DaVinci GPIO Support
*
* Copyright (c) 2006 David Brownell
* Copyright (c) 2007, MontaVista Software, Inc. <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/bitops.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/hardware/clock.h>
#include <asm/arch/irqs.h>
#include <asm/arch/hardware.h>
#include <asm/arch/gpio.h>
#include <asm/arch/cpu.h>
#include <asm/mach/irq.h>
/*
該文件實現了gpio的各種應用功能和向內核註冊gpio的中斷例程等功能。
用戶的驅動程序可調用gpio_request和gpio_free使用或釋放該gpio,
可以調用gpio_direction_input和gpio_direction_output函數設置gpio輸入輸出方向,
調用gpio_get_value和gpio_set_value獲取設置值。
*/
static DEFINE_SPINLOCK(gpio_lock);
/* 總共有DAVINCI_N_GPIO(71)個gpio引腳,故使用相應多的bit來記錄這些引腳的使用狀態 */
static DECLARE_BITMAP(gpio_in_use, DAVINCI_N_GPIO);
/*
申請一個gpio,其實就是檢查該gpio是否空閒,如果空閒就可以使用並將該gpio相應的bit置位
(在gpio_in_use中)。
*/
int gpio_request(unsigned gpio, const char *tag)
{
if (gpio >= DAVINCI_N_GPIO)
return -EINVAL;
if (test_and_set_bit(gpio, gpio_in_use))
return -EBUSY;
return 0;
}
EXPORT_SYMBOL(gpio_request);
/*
釋放一個gpio,其實就是清除gpio相應的控制bit位(在gpio_in_use中)。
*/
void gpio_free(unsigned gpio)
{
if (gpio >= DAVINCI_N_GPIO)
return;
clear_bit(gpio, gpio_in_use);
}
EXPORT_SYMBOL(gpio_free);
/* 獲得gpio_controller結構體指針,gpio_controller結構體是gpio的核心控制單元,裏面包含
gpio的設置和數據寄存器。該結構體和__gpio_to_controller函數在/include/asm-arm/
arch-davinci/gpio.h中定義,具體如下:
struct gpio_controller {
u32 dir;
u32 out_data;
u32 set_data;
u32 clr_data;
u32 in_data;
u32 set_rising;
u32 clr_rising;
u32 set_falling;
u32 clr_falling;
u32 intstat;
};
static inline struct gpio_controller *__iomem
__gpio_to_controller(unsigned gpio)
{
void *__iomem ptr;
if (gpio >= DAVINCI_N_GPIO)
return NULL;
if (gpio < 32)
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x10);
else if (gpio < 64)
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x38);
else if (gpio < 96)
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x60);
else
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x88);
return ptr;
}
由上面的定義和ti的SPRUE25.pdf手冊可以看出,__gpio_to_controller函數返回的是
gpio_controller結構體到第一個成員dir的虛擬地址。獲取了這個結構體指針後,
便可以控制相應的gpio了。dm644x共有71個gpio,
所以使用三個gpio_controller結構體控制,關於這個後面會由更詳細的分析,
*/
/* create a non-inlined version */
static struct gpio_controller *__iomem gpio2controller(unsigned gpio)
{
return __gpio_to_controller(gpio);
}
/*
向某個gpio設置值,0或1。如果向gpio寫1,則向set_data寄存器相應的位置1,如果寫0,
則向clr_data寄存器相應的位置1.__gpio_mask函數在gpio.h中定義,定義如下,
static inline u32 __gpio_mask(unsigned gpio)
{
return 1 << (gpio % 32);
}
因爲71個引腳由3個結構體控制,第一個控制前32個gpio,第二個控制次32個gpio,
最後一個控制剩餘的7個gpio,故__gpio_mask函數的作用是找到在其相應控制結構體裏的偏移數,
比如gpio34,那麼其由第二個結構體控制,在這個機構體裏的偏移是3(從0開始算,就是第二位)。
使用這個函數之前,必須確認該gpio設置成輸出模式。
*/
/*
* Assuming the pin is muxed as a gpio output, set its output value.
*/
void __gpio_set(unsigned gpio, int value)
{
struct gpio_controller *__iomem g = gpio2controller(gpio);
// 設置gpio的值
__raw_writel(__gpio_mask(gpio), value ? &g->set_data : &g->clr_data);
}
EXPORT_SYMBOL(__gpio_set);
/*
通過讀取in_data寄存器相應該gpio的位來讀取gpio的值。
使用這個函數之前,必須確認該gpio設置成輸入模式,否則獲得到值不可預料。
*/
/*
* Read the pin's value (works even if it's set up as output);
* returns zero/nonzero.
*
* Note that changes are synched to the GPIO clock, so reading values back
* right after you've set them may give old values.
*/
int __gpio_get(unsigned gpio)
{
struct gpio_controller *__iomem g = gpio2controller(gpio);
/* 讀取gpio的值,!!的目的是使得返回的值爲0或1.*/
return !!(__gpio_mask(gpio) & __raw_readl(&g->in_data));
} }
EXPORT_SYMBOL(__gpio_get);
/*
通過dir寄存器相應該gpio的位來設置gpio輸入輸出方向,爲0,則設置成輸出,爲1,則設置出輸入。
該函數是設置成輸入,故設置dir寄存器爲1.
正如應爲所說的,必須確認該引腳是作爲gpio功能,而不是某個模塊到功能,比如spi。通過PINMUX0
和PINMUX1兩個寄存器來設置。
*/
/*--------------------------------------------------------------------------*/
/*
* board setup code *MUST* set PINMUX0 and PINMUX1 as
* needed, and enable the GPIO clock.
*/
int gpio_direction_input(unsigned gpio)
{
struct gpio_controller *__iomem g = gpio2controller(gpio);
u32 temp;
u32 mask;
if (!g)
return -EINVAL;
spin_lock(&gpio_lock);
mask = __gpio_mask(gpio);
temp = __raw_readl(&g->dir);
temp |= mask; // 設置成1
__raw_writel(temp, &g->dir); // 設置該gpio爲輸入
spin_unlock(&gpio_lock);
return 0;
}
EXPORT_SYMBOL(gpio_direction_input);
/*
通過dir寄存器相應該gpio的位來設置gpio輸入輸出方向,爲0,則設置成輸出,爲1,則設置出輸入。
該函數是設置成輸出,故設置dir寄存器爲0.
value參數用於選擇gpio設置成輸出後該gpio輸出的值。
*/
int gpio_direction_output(unsigned gpio, int value)
{
struct gpio_controller *__iomem g = gpio2controller(gpio);
u32 temp;
u32 mask;
if (!g)
return -EINVAL;
spin_lock(&gpio_lock);
mask = __gpio_mask(gpio);
temp = __raw_readl(&g->dir);
temp &= ~mask; // 設置成0
//設置該gpio輸出值
__raw_writel(mask, value ? &g->set_data : &g->clr_data);
__raw_writel(temp, &g->dir); // 設置gpio爲輸出
spin_unlock(&gpio_lock);
return 0;
}
EXPORT_SYMBOL(gpio_direction_output);
/*
向gpio設置值,0或1。
*/
void gpio_set_value(unsigned gpio, int value)
{
if (__builtin_constant_p(value)) {
struct gpio_controller *__iomem g;
u32 mask;
if (gpio >= DAVINCI_N_GPIO)
__error_inval_gpio();
g = __gpio_to_controller(gpio);
mask = __gpio_mask(gpio);
if (value)
__raw_writel(mask, &g->set_data); // 該gpio輸出高
else
__raw_writel(mask, &g->clr_data); // 該gpio輸出低
return;
}
__gpio_set(gpio, value);
}
EXPORT_SYMBOL(gpio_set_value);
/*
讀取gpio的值,0或1.
*/
int gpio_get_value(unsigned gpio)
{
struct gpio_controller *__iomem g;
if (!__builtin_constant_p(gpio))/* 判斷該gpio值是否爲編譯時常數,如果是常數,
函數返回 1,否則返回 0 */
return __gpio_get(gpio);
if (gpio >= DAVINCI_N_GPIO)
return __error_inval_gpio();
g = __gpio_to_controller(gpio);
// 讀取該gpio的值
return !!(__gpio_mask(gpio) & __raw_readl(&g->in_data));
}
EXPORT_SYMBOL(gpio_get_value);
/*
* We expect irqs will normally be set up as input pins, but they can also be
* used as output pins ... which is convenient for testing.
*
* NOTE: GPIO0..GPIO7 also have direct INTC hookups, which work in addition
* to their GPIOBNK0 irq (but with a bit less overhead). But we don't have
* a good way to hook those up ...
*
* All those INTC hookups (GPIO0..GPIO7 plus five IRQ banks) can also
* serve as EDMA event triggers.
*/
/*
禁止相應該irq的gpio的中斷。每個gpio都可以作爲中斷的來源,其中gpio0-gpio7是獨立的中斷來源,
也就是分配獨立的中斷號,其他gpio則共用5個GPIOBNK中斷線。其優先級可以在board-evm.c
中設置(已經介紹過)。在dm644x平臺上,中斷是電平邊緣觸發的,禁止中斷其實就是既不設置
上升沿觸發,也不設置下降沿觸發。
*/
static void gpio_irq_disable(unsigned irq)
{
struct gpio_controller *__iomem g = get_irq_chipdata(irq);
u32 mask = __gpio_mask(irq_to_gpio(irq));
__raw_writel(mask, &g->clr_falling); // 清除下降沿觸發
__raw_writel(mask, &g->clr_rising); // 清除上升沿觸發
}
/*
中斷使能。
在dm644x平臺上,中斷是電平邊緣觸發的,其實就是設置爲上升沿或下降沿中斷。
*/
static void gpio_irq_enable(unsigned irq)
{
struct gpio_controller *__iomem g = get_irq_chipdata(irq);
u32 mask = __gpio_mask(irq_to_gpio(irq));
// 如果先前爲下降沿中斷,則使能爲下降沿中斷
if (irq_desc[irq].status & IRQT_FALLING)
__raw_writel(mask, &g->set_falling);
// 如果先前爲上升沿中斷,則使能爲上升沿中斷
if (irq_desc[irq].status & IRQT_RISING)
__raw_writel(mask, &g->set_rising);
}
/*
設置中斷類型。
在dm644x平臺上,中斷有上升沿和下降沿兩種觸發方式。
*/
static int gpio_irq_type(unsigned irq, unsigned trigger)
{
struct gpio_controller *__iomem g = get_irq_chipdata(irq);
u32 mask = __gpio_mask(irq_to_gpio(irq));
if (trigger & ~(IRQT_FALLING | IRQT_RISING))
return -EINVAL;
irq_desc[irq].status &= ~IRQT_BOTHEDGE;
irq_desc[irq].status |= trigger;
__raw_writel(mask, (trigger & IRQT_FALLING)
? &g->set_falling : &g->clr_falling); // 設置爲下降沿觸發
__raw_writel(mask, (trigger & IRQT_RISING)
? &g->set_rising : &g->clr_rising); // 設置爲上升沿觸發
return 0;
}
/*
該結構體用於註冊到所有irq的中斷描述結構體中(struct irqdesc),
而所有中斷描述結構體定義成一個全局數組irq_desc 。
*/
static struct irqchip gpio_irqchip = {
.unmask = gpio_irq_enable, /* 用於使能中斷,
在enable_irq()等內核函數中會用到。*/
.mask = gpio_irq_disable,/* 用於禁止中斷,
在disable_irq()等內核函數中會用到。*/
.type = gpio_irq_type, /* 用於設置中斷類型,
在set_irq_type()內核函數中會用到。*/
};
/*
該函數將在下面的davinci_gpio_irq_setup中使用,將被註冊到五個gpio bank中斷的
irq_desc結構中,目的是處理所有級聯的gpio中斷。所謂級聯的中斷, 就是指有n箇中斷
共用同一個中斷線。
在dm644x平臺中,除了gpio0-gpio7外,其他63個gpio都共用五個gpiobank中斷線,在這裏,
gpio0-gpio7也被註冊到gpiobank中斷線,但實際上並不會使用,因爲它們擁有自己的
中斷線。其中,gpio0-gpio15共用IRQ_GPIOBNK0(56)中斷線,gpio16-gpio31共用
IRQ_GPIOBNK1(57)中斷線,gpio32-gpio47共用IRQ_GPIOBNK2(58)中斷線,
gpio48-gpio63共用IRQ_GPIOBNK4(59)中斷線,gpio64-gpio70共用
IRQ_GPIOBNK5(60)中斷線,
因爲寄存器是32位的,所以實際上只有三組寄存器,第一組包含bank0和bank1,
也就是gpio0-gpio31,第二組包含bank2和bank3,也就是gpio32-gpio63,
第三組包含bank4和bank5,也就是gpio64-gpio70,剩餘了25個位沒有使用。
*/
static void
gpio_irq_handler(unsigned irq, struct irqdesc *desc, struct pt_regs *regs)
{
struct gpio_controller *__iomem g = get_irq_chipdata(irq);
u32 mask = 0xffff;
/* we only care about one bank */
// 如果bank中斷線是寄數,則說明該中斷的中斷狀態位在INTSTATn寄存器的高16位
if (irq & 1)
mask <<= 16;
/* temporarily mask (level sensitive) parent IRQ */
desc->chip->ack(irq);// 該ack函數會在arch/arm/mach-davinci/irq.c中註冊。
while (1) {
u32 status;
struct irqdesc *gpio;
int n;
int res;
/* ack any irqs */
/*gpio中斷髮生後,硬件會在INTSTATn寄存器中置位相應位,
以備程序查詢,確定是哪個gpio*/
status = __raw_readl(&g->intstat) & mask;
if (!status)
break;
__raw_writel(status, &g->intstat); // 向該位寫1清除
if (irq & 1)
status >>= 16;
/* now demux them to the right lowlevel handler */
// 從下面的davinci_gpio_irq_setup函數可以看出來以下程序的運作。
n = (int)get_irq_data(irq); // 獲取該bank對應的第一個gpio號
gpio = &irq_desc[n]; // 獲取該bank第一個gpio號對應的中斷描述符
while (status) { // 該bank可能有多個gpio發生了中斷
res = ffs(status); // 獲取第一個發生了中斷的位(1-32)
n += res; /* 獲得該gpio的中斷線(系統實際上只有64(0-63)箇中斷線,
但那些共用的gpio的中斷也有自己的斷描述符和中斷線(從64開始),
僅僅是爲了管理,不能通過request_irq()函數來申請。*/
gpio += res; // 獲得該gpio的中斷描述符
/* 調用下面註冊的do_simple_IRQ例程
其又會調用用戶通過request_irq()
註冊的中斷例程
*/
desc_handle_irq(n - 1, gpio - 1, regs);
status >>= res;
}
}
desc->chip->unmask(irq); // 打開該irq中斷線
/* now it may re-trigger */
}
/*
* NOTE: for suspend/resume, probably best to make a sysdev (and class)
* with its suspend/resume calls hooking into the results of the set_wake()
* calls ... so if no gpios are wakeup events the clock can be disabled,
* with outputs left at previously set levels, and so that VDD3P3V.IOPWDN0
* can be set appropriately for GPIOV33 pins.
*/
/*
註冊gpio中斷例程到內核中,並初始化了一些寄存器。
該函數將會被board_evm.c(其淺析已經發表)中的evm_init()函數調用。具體調用過程如下:
start_kernel()-->setup_arch()-->init_machine = mdesc->init_machine
(init_machine是個全局函數指針變量,其指向的就是已經註冊到機器描述符裏evm_init());
調用函數指針init_machine()的例程是customize_machine(),其定義爲
arch_initcall(customize_machine),所以,接下來的調用過程是:
start_kernel()-->do_basic_setup()-->do_initcalls()-->customize_machine()-->
init_machine()(也就是evm_init())-->davinci_gpio_irq_setup。
從上可以看出經歷了兩個過程,才調用davinci_gpio_irq_setup例程來初始化gpio中斷。
*/
int __init davinci_gpio_irq_setup(void)
{
unsigned gpio, irq, bank, banks;
struct clk *clk;
clk = clk_get(NULL, "gpio"); // 獲取時鐘
if (IS_ERR(clk)) {
printk(KERN_ERR "Error %ld getting gpio clock?\n",
PTR_ERR(clk));
return 0;
}
clk_enable(clk); // 使能gpio時鐘並打開該模塊電源
for (gpio = 0, irq = gpio_to_irq(0), bank = (cpu_is_davinci_dm355() ?
IRQ_DM355_GPIOBNK0 : (cpu_is_davinci_dm6467() ?
IRQ_DM646X_GPIOBNK0 : IRQ_GPIOBNK0)); // dm644x的IRQ_GPIOBNK0(56)
gpio < DAVINCI_N_GPIO; bank++) { // dm644x的DAVINCI_N_GPIO(71)
struct gpio_controller *__iomem g = gpio2controller(gpio);
unsigned i;
// 關該bank所有gpio的中斷
__raw_writel(~0, &g->clr_falling);
__raw_writel(~0, &g->clr_rising);
/* set up all irqs in this bank */
// 同一個bank的所有gpio共用一箇中斷例程gpio_irq_handler
set_irq_chained_handler(bank, gpio_irq_handler);
set_irq_chipdata(bank, g);
set_irq_data(bank, (void *)irq);
for (i = 0; i < 16 && gpio < DAVINCI_N_GPIO;
i++, irq++, gpio++) {
set_irq_chip(irq, &gpio_irqchip); /* 註冊用於gpio中斷禁止、設能
和類型選擇的回調例程 */
set_irq_chipdata(irq, g); // 保存控制結構體(寄存器)的地址
set_irq_handler(irq, do_simple_IRQ);/* 爲每個gpio中斷設置同一個中
斷例程do_simple_IRQ*/
set_irq_flags(irq, IRQF_VALID); // fiq中斷有效
}
}
/*
一個共用bank中斷線的gpio中斷髮生後的大致的流程是:
--> gpio_irq_handler --> do_simple_IRQ --> __do_irq -->
action->handler(用戶使用request_irq()註冊的中斷例程)
*/
/* BINTEN -- per-bank interrupt enable. genirq would also let these
* bits be set/cleared dynamically.
*/
if (cpu_is_davinci_dm355())
banks = 0x3f;
else
banks = 0x1f;
// 向BINTEN寄存器寫入0x1f(共5個位,每個位控制1個bank),打開所有的bank中斷
__raw_writel(banks, (void *__iomem)
IO_ADDRESS(DAVINCI_GPIO_BASE + 0x08));
printk(KERN_INFO "DaVinci: %d gpio irqs\n", irq - gpio_to_irq(0));
return 0;
}
gpio.h
/*
* TI DaVinci GPIO Support
*
* Copyright (c) 2006 David Brownell
* Copyright (c) 2007, MontaVista Software, Inc. <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __DAVINCI_GPIO_H
#define __DAVINCI_GPIO_H
/*
* basic gpio routines
*
* board-specific init should be done by arch/.../.../board-XXX.c (maybe
* initializing banks together) rather than boot loaders; kexec() won't
* go through boot loaders.
*
* the gpio clock will be turned on when gpios are used, and you may also
* need to pay attention to PINMUX0 and PINMUX1 to be sure those pins are
* used as gpios, not with other peripherals.
*
* GPIOs are numbered 0..(DAVINCI_N_GPIO-1). For documentation, and maybe
* for later updates, code should write GPIO(N) or:
* - GPIOV18(N) for 1.8V pins, N in 0..53; same as GPIO(0)..GPIO(53)
* - GPIOV33(N) for 3.3V pins, N in 0..17; same as GPIO(54)..GPIO(70)
*
* For GPIO IRQs use gpio_to_irq(GPIO(N)) or gpio_to_irq(GPIOV33(N)) etc
* for now, that's != GPIO(N)
*/
#define GPIO(X) (X) /* 0 <= X <= 70 */
#define GPIOV18(X) (X) /* 1.8V i/o; 0 <= X <= 53 */
#define GPIOV33(X) ((X)+54) /* 3.3V i/o; 0 <= X <= 17 */
/*
寄存器都是32位到,每位對應一個gpio。
*/
struct gpio_controller {
u32 dir; // gpio方向設置寄存器
u32 out_data; // gpio設置爲輸出時,表示輸出狀態(0或1)
u32 set_data; // gpio設置爲輸出時,用於輸出高電平
u32 clr_data; // gpio設置爲輸出時,用於輸出低電平
u32 in_data; // gpio設置爲輸入時,用於讀取輸入值
u32 set_rising; // gpio中斷上升沿觸發設置
u32 clr_rising; // gpio中斷上升沿觸發清除
u32 set_falling; // gpio中斷下降沿觸發設置
u32 clr_falling; // gpio中斷下降沿觸發清除
u32 intstat; // gpio中斷狀態位,由硬件設置,可讀取,寫1時清除。
};
/* The __gpio_to_controller() and __gpio_mask() functions inline to constants
* with constant parameters; or in outlined code they execute at runtime.
*
* You'd access the controller directly when reading or writing more than
* one gpio value at a time, and to support wired logic where the value
* being driven by the cpu need not match the value read back.
*
* These are NOT part of the cross-platform GPIO interface
*/
static inline struct gpio_controller *__iomem
__gpio_to_controller(unsigned gpio)
{
void *__iomem ptr;
if (gpio >= DAVINCI_N_GPIO)
return NULL;
if (gpio < 32)
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x10);
else if (gpio < 64)
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x38);
else if (gpio < 96)
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x60);
else
ptr = (void *__iomem)IO_ADDRESS(DAVINCI_GPIO_BASE + 0x88);
return ptr;
}
static inline u32 __gpio_mask(unsigned gpio)
{
return 1 << (gpio % 32);
}
/* The get/set/clear functions will inline when called with constant
* parameters, for low-overhead bitbanging. Illegal constant parameters
* cause link-time errors.
*
* Otherwise, calls with variable parameters use outlined functions.
*/
extern int __error_inval_gpio(void);
extern void __gpio_set(unsigned gpio, int value);
extern int __gpio_get(unsigned gpio);
/* Returns zero or nonzero; works for gpios configured as inputs OR
* as outputs.
*
* NOTE: changes in reported values are synchronized to the GPIO clock.
* This is most easily seen after calling gpio_set_value() and then immediatly
* gpio_get_value(), where the gpio_get_value() would return the old value
* until the GPIO clock ticks and the new value gets latched.
*/
extern int gpio_get_value(unsigned gpio);
extern void gpio_set_value(unsigned gpio, int value);
/* powerup default direction is IN */
extern int gpio_direction_input(unsigned gpio);
extern int gpio_direction_output(unsigned gpio, int value);
#include <asm-generic/gpio.h> /* cansleep wrappers */
extern int gpio_request(unsigned gpio, const char *tag);
extern void gpio_free(unsigned gpio);
static inline int gpio_to_irq(unsigned gpio)
{
return DAVINCI_N_AINTC_IRQ + gpio;
}
static inline int irq_to_gpio(unsigned irq)
{
return irq - DAVINCI_N_AINTC_IRQ;
}
#endif /* __DAVINCI_GPIO_H */
原文地址:http://blog.csdn.net/heanyu/article/details/6709571Linux下gpio的相關函數分析
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