gpio_request 原形代碼

?? 其原型為 **int gpio_request(unsigned gpio, const char *label)** 先說說其參數，gpio則為你要申請的哪一個管腳，label則是為其取一個名字。其具體實現如下：

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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，也就是參數的取值范圍判斷? ??
?????????????goto?done;???
????????desc?=?&gpio_desc[gpio];???
//這個是關鍵gpio_desc為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里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就為空了，隨后就直接返回-EINVAL了。? ??
if?(chip?==?NULL)如果不為空繼續往下走???
??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)?{??
//這里測試并設置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;???
}??

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，也就是參數的取值范圍判斷 
goto done; 
desc = &gpio_desc[gpio]; 
//這個是關鍵gpio_desc為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里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就為空了，隨后就直接返回-EINVAL了。 
if (chip == NULL)如果不為空繼續往下走 
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) {
//這里測試并設置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：?

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/*??
*?TI?DaVinci?GPIO?Support??
*??
*??
*?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注冊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是否空閑，如果空閑就可以使用并將該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，里面包含??
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后，??
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，關于這個后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);??
}??
因為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，??
最后一個控制剩余的7個gpio，故__gpio_mask函數的作用是找到在其相應控制結構體里的偏移數，??
比如gpio34,那么其由第二個結構體控制，在這個機構體里的偏移是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為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，為0，則設置成輸出，為1，則設置出輸入。??
該函數是設置成輸入，故設置dir寄存器為1.??
?正如應為所說的，必須確認該引腳是作為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為輸入? ??
????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，為0，則設置成輸出，為1，則設置出輸入。??
該函數是設置成輸出，故設置dir寄存器為0.??
value參數用于選擇gpio設置成輸出后該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為輸出? ??
????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值是否為編譯時常數，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都可以作為中斷的來源，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，其實就是設置為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));???
??
????//?如果先前為下降沿中斷，則使能為下降沿中斷? ??
??
????if?(irq_desc[irq].status?&?IRQT_FALLING)???
????????__raw_writel(mask,?&g->set_falling);???
???????
????//?如果先前為上升沿中斷，則使能為上升沿中斷? ??
??
????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);?????//?設置為下降沿觸發? ??
??
????__raw_writel(mask,?(trigger?&?IRQT_RISING)???
???????????&g->set_rising?:?&g->clr_rising);????//?設置為上升沿觸發? ??
??
????return?0;???
}???
??
/*???
該結構體用于注冊到所有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,?/*?用于使能中斷，??
?????????????????????????????????????在enable_irq()等內核函數中會用到。*/???????
????.mask????????=?gpio_irq_disable,/*?用于禁止中斷，??
?????????????????????????????????????在disable_irq()等內核函數中會用到。*/???
????.type????????=?gpio_irq_type,?/*?用于設置中斷類型，??
?????????????????????????????????????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，將被注冊到五個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個中斷??
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，在這里，??
gpio0-gpio7也被注冊到gpiobank中斷線，但實際上并不會使用，因為它們擁有自己的??
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，??
因為寄存器是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，剩余了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中注冊。? ??
??
????while?(1)?{???
????????u32????????status;???
????????struct?irqdesc????*gpio;???
????????int????????n;???
????????int????????res;???
??
????????/*?ack?any?irqs?*/???
????????/*gpio中斷發生后，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）個中斷線，??
????????????????????????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），??
????????????????????????僅僅是為了管理，不能通過request_irq()函數來申請。*/???
????????????gpio?+=?res;????//?????獲得該gpio的中斷描述符? ??
??
???????????????
????????????/*?調用下面注冊的do_simple_IRQ例程??
?????????????其又會調用用戶通過request_irq()??
?????????????注冊的中斷例程??
????????????*/???
????????????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.??
*/???
/*??
注冊gpio中斷例程到內核中，并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，其指向的就是已經注冊到機器描述符里evm_init())；??
調用函數指針init_machine()的例程是customize_machine()，其定義為??
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時鐘并打開該模塊電源? ??
??
??
????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共用一個中斷例程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);????/*?注冊用于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);/*?為每個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中斷發生后的大致的流程是：??
-->?gpio_irq_handler?-->?do_simple_IRQ?-->?__do_irq?-->???
action->handler（用戶使用request_irq()注冊的中斷例程）??
*/???
????/*?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??
*??
*??
*?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設置為輸出時，表示輸出狀態(0或1)? ??
??
????u32????set_data;????????//?gpio設置為輸出時，用于輸出高電平? ??
??
????u32????clr_data;????????//?gpio設置為輸出時，用于輸出低電平? ??
??
????u32????in_data;????????//?gpio設置為輸入時，用于讀取輸入值? ??
??
????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?*/ ??
???

/* 
* TI DaVinci GPIO Support 
* 
* Copyright (c) 2006 David Brownell 
* Copyright (c) 2007, MontaVista Software, Inc. <source@mvista.com> 
* 
* 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注冊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是否空閑，如果空閑就可以使用并將該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，里面包含 
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后， 
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，關于這個后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); 
} 
因為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， 
最后一個控制剩余的7個gpio，故__gpio_mask函數的作用是找到在其相應控制結構體里的偏移數， 
比如gpio34,那么其由第二個結構體控制，在這個機構體里的偏移是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為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，為0，則設置成輸出，為1，則設置出輸入。 
該函數是設置成輸入，故設置dir寄存器為1. 
正如應為所說的，必須確認該引腳是作為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為輸入 
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，為0，則設置成輸出，為1，則設置出輸入。 
該函數是設置成輸出，故設置dir寄存器為0. 
value參數用于選擇gpio設置成輸出后該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為輸出 
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值是否為編譯時常數，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都可以作為中斷的來源，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，其實就是設置為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)); 
// 如果先前為下降沿中斷，則使能為下降沿中斷 
if (irq_desc[irq].status & IRQT_FALLING) 
__raw_writel(mask, &g->set_falling); 
// 如果先前為上升沿中斷，則使能為上升沿中斷 
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);     // 設置為下降沿觸發 
__raw_writel(mask, (trigger & IRQT_RISING) 
? &g->set_rising : &g->clr_rising);    // 設置為上升沿觸發 
return 0; 
} 
/*  
該結構體用于注冊到所有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, /* 用于使能中斷， 
在enable_irq()等內核函數中會用到。*/     
.mask        = gpio_irq_disable,/* 用于禁止中斷， 
在disable_irq()等內核函數中會用到。*/ 
.type        = gpio_irq_type, /* 用于設置中斷類型， 
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，將被注冊到五個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個中斷 
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，在這里， 
gpio0-gpio7也被注冊到gpiobank中斷線，但實際上并不會使用，因為它們擁有自己的 
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， 
因為寄存器是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，剩余了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中注冊。 
while (1) { 
u32        status; 
struct irqdesc    *gpio; 
int        n; 
int        res; 
/* ack any irqs */ 
/*gpio中斷發生后，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）個中斷線， 
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）， 
僅僅是為了管理，不能通過request_irq()函數來申請。*/ 
gpio += res;    //     獲得該gpio的中斷描述符 
/* 調用下面注冊的do_simple_IRQ例程 
其又會調用用戶通過request_irq() 
注冊的中斷例程 
*/ 
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. 
*/ 
/* 
注冊gpio中斷例程到內核中，并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，其指向的就是已經注冊到機器描述符里evm_init())； 
調用函數指針init_machine()的例程是customize_machine()，其定義為 
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時鐘并打開該模塊電源 
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共用一個中斷例程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);    /* 注冊用于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);/* 為每個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中斷發生后的大致的流程是： 
--> gpio_irq_handler --> do_simple_IRQ --> __do_irq -->  
action->handler（用戶使用request_irq()注冊的中斷例程） 
*/ 
/* 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. <source@mvista.com> 
* 
* 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設置為輸出時，表示輸出狀態(0或1) 
u32    set_data;        // gpio設置為輸出時，用于輸出高電平 
u32    clr_data;        // gpio設置為輸出時，用于輸出低電平 
u32    in_data;        // gpio設置為輸入時，用于讀取輸入值 
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 */