Introduction to omap4 pad configuration

Introduction to OMAP4 Pad Configuration

Jiahe Jou

2012/12/13

RevisionsDATE AUTHOUR DESCRIPTION

2012/12/03 Jiahe Jou Draft.

Outline● Overview

● Pad Configuration

● Off Mode Control

● Wake Up Detection

● Power Optimization

● Configuration How To

● Case Study - Talos7

Overview● Configure pads to desired values according to device configuration

● Two sets of 32-bit pad configuration register

○ CORE power domain

○ WKUP power domain

● Each register has two pads with five fields functional bits

○ MUXMODE (3 bits)

○ PULL (2 bits)

○ INPUT ENABLE (1 bits)

○ OFF MODE VALUE (5 bits)

○ WAKE UP (2 bits)

Overview● Pad configuration register

2

Pad Configuration● Mode selection

○ MUXMODE (3 bits), 0b000 ~ 0b111

○ Functional modes, 0b000 ~ 0b110

MUXMODE Selected Mode

0b000 Mode 0, primary mode

0b001 Mode 1

0b010 Mode 2

0b011 Mode 3

0b100 Mode 4

0b101 Mode 5

0b110 Mode 6

0b111 Mode 7, safe mode

Pad Configuration● Examples

Pad Configuration● Pull selection

○ PULL (2 bits), 0b00 ~ 0b11

PULLBehavior

PULL TYPE PULL ENABLE

0b0 0b0 Pull Down, Not Activated

0b0 0b1 Pull Down, Activated

0b1 0b0 Pull Up, Not Activated

0b1 0b1 Pull Up, Activated

● Input enable

○ 0, input disable, output mode

○ 1, input enable, bidirectional mode

Pad Configuration● Off mode value

○ OFFMODEENABLE, off mode override control, 1 enable 0 disable

○ OFFMODEOUTENABLE, off mode output enable, 0 enable 1 disable

○ OFFMODEOUTVALUE, off mode output value

○ OFFMODEPULLUDENABLE, off mode pull up/down enable

○ OFFMODEPULLTYPESELECT, off mode pull type select

● Wake Up

○ WAKEUPENABLE, wake up detect enable

○ WAKEUPEVENT, wake up event status

Pad Configuration

Off Mode Control● Off mode selected

○ PRM_DEVICE_OFF_CTRL[0] DEVICE_OFF_ENABLE

○ CONTROL_PADCONF_GLOBAL[31] FORCE_OFFMODE_ENABLE

Wake Up Dectection● Wake up enabled

○ PRM_IO_PMCTRL[16]GLOBAL_WUEN

Power Optimization● Pin types

● Avoid unconnected or incorrectly pulled pins

○ For input, use pull up/down when possible

○ For output, avoid pull conflicts

○ For bi-direction, reconfigure the pin as an output driving 0

Power Optimization

Pad Configuration● Avoid unconnected pin (1)

○ If not driven externally, pull up/down is required

● Avoid pull conflict (2)

○ Prevent different pulls on the same line

● Avoid logic conflict (3)

○ if no external device drive the line, set the value as 0

○ else same value must

Pad Configuration● Recommended configuration for unconnected pads

Pad Configuration● Ball Characteristics

Configuration How To● Boot-loader

struct pad_conf_entry {

u16 offset;

u16 val;

};

● Kernel/* omap_mux_init_gpio - initialize a signal based on the GPIO number */

int omap_mux_init_gpio(int gpio, int val);

/* omap_mux_init_signal - initialize a signal based on the signal name */

int omap_mux_init_signal(const char *muxname, int val);

Configuration How To● Kernel

/* Centralized control for pad init, suspend and shutdown */

struct omap_pad_state_description {

char *init_mux_name;

u16 init_config;

char *suspend_mux_name;

u16 suspend_config;

char *shutdown_mux_name;

u16 shutdown_config;

u8 flags;

};

Case Study - Talos7

{GPMC_AD0, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat0: eMMC_AD0 */








Case Study - Talos7

{SDMMC1_DAT4, (PTD | IDIS | M7)}, /* sdmmc1_dat4: NC: SafeMode */




Case Study - Talos7omap_mux_init_gpio(GPIO_WIFI_IRQ, OMAP_PIN_INPUT | OMAP_PIN_OFF_WAKEUPENABLE);

omap_mux_init_gpio(GPIO_WIFI_PMENA, OMAP_PIN_OUTPUT);

omap_mux_init_signal("sdmmc5_cmd", OMAP_PIN_INPUT_PULLUP);

omap_mux_init_signal("sdmmc5_clk", OMAP_PIN_INPUT_PULLUP);

omap_mux_init_signal("sdmmc5_dat0", OMAP_PIN_INPUT_PULLUP);




Case Study - Talos7static struct omap_pad_state_description talos_dynamic_pads[] __initdata = {

...

/*sdmmc2_clk */

{

.init_mux_name = "gpmc_noe.sdmmc2_clk",

.init_config = OMAP_PIN_INPUT_PULLUP,

},

/*sdmmc2_cmd */

{

.init_mux_name = "gpmc_nwe.sdmmc2_cmd",

.init_config = OMAP_PIN_INPUT_PULLUP,

}

...

}

Q&A

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Introduction to omap4 pad configuration

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Introduction to omap4 pad configuration