UM0851 datasheet(35/245 Pages) STMICROELECTRONICS

35 / 245 page

UM0851

Platform section

Doc ID 16604 Rev 2

35/245

High level IRQ flow handlers

The generic layer provides a set of pre-defined IRQ-flow methods:

●

handle_level_irq(): provides a generic implementation for level-triggered interrupts

●

handle_edge_irq(): provides a generic implementation for edge-triggered interrupts

●

handle_simple_irq(): provides a generic implementation for simple interrupts. The

simple flow handler does not call any handler/chip primitives

●

handle_percpu_irq(): provides a generic implementation for per CPU interrupts. Per

CPU interrupts are only available on SMP and the handler provides a simplified version

without locking.

The interrupt flow handlers (either predefined or architecture-specific) are assigned to

specific interrupts by the architecture either during the boot up or during the device

initialization.

In the SPEAr architecture, at boot up time, the architecture specific code sets up the

handle_level_irq flow method as the default for all the VIC interrupts. This is done in

<arch/arm/mach-spearxxx/irq.c>. Below is a part of the code captured from the SPEAr300

architecture-related initialization code for VIC.

void __init spear3xx_init_irq(void)

{

unsigned int i;

do_init_irq(1);

for (i = IRQ_VIC_START; i <= IRQ_VIC_END; i++)

{

set_irq_chip(i, &vic_chip);

set_irq_handler(i, handle_level_irq);

set_irq_flags(i, IRQF_VALID | IRQF_PROBE);

}

Chip level hardware encapsulation

The chip level hardware descriptor structure structs irq_chip contains all the direct chip

relevant functions, which can be utilized by the IRQ flow implementations.

●

ack()

●

mask_ack() - optional, recommended for performance

●

mask()

●

unmask()

●

retrigger() - optional

●

set_type() - optional

●

set_wake() - optional

These primitives mean exactly what their name says: ack means ACK, masking means

masking of an IRQ line, etc. It is up to the flow handler(s) to use these basic units of low-

level functionality.

struct irq_chip is a hardware interrupt chip descriptor described below:

struct irq_chip {

const char*name;

unsigned int(*startup)(unsigned int irq);

void

(*shutdown)(unsigned int irq);

void

(*enable)(unsigned int irq);

void

(*disable)(unsigned int irq);

UM0851 Arkusz danych(PDF) 35 Page - STMicroelectronics

UM0851 Arkusz danych(HTML) 35 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Arkusz danych Pobierz

Link URL