Introduction to omap4 pad configuration
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This document provides an introduction to OMAP4 pad configuration. It describes how to configure pads through 32-bit pad configuration registers for different power domains and functions. These include selecting pad modes, pull settings, input/output control, off mode values, and wake up detection. It also discusses power optimization techniques and provides examples of pad configuration code for the Linux kernel and a case study of pad configuration for the Talos7 board.
![Off Mode Control
● Off mode selected
○ PRM_DEVICE_OFF_CTRL[0] DEVICE_OFF_ENABLE
○ CONTROL_PADCONF_GLOBAL[31] FORCE_OFFMODE_ENABLE](https://image.slidesharecdn.com/20121213jiahejouintroductiontoomap4padconfiguration-121212214407-phpapp01/85/Introduction-to-omap4-pad-configuration-11-320.jpg)
![Wake Up Dectection
● Wake up enabled
○ PRM_IO_PMCTRL[16]GLOBAL_WUEN](https://image.slidesharecdn.com/20121213jiahejouintroductiontoomap4padconfiguration-121212214407-phpapp01/85/Introduction-to-omap4-pad-configuration-12-320.jpg)
![Case Study - Talos7
static 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,
}
...
}](https://image.slidesharecdn.com/20121213jiahejouintroductiontoomap4padconfiguration-121212214407-phpapp01/85/Introduction-to-omap4-pad-configuration-23-320.jpg)
Introduction to omap4 pad configuration
- 1. Introduction to OMAP4 Pad Configuration Jiahe Jou 2012/12/13
- 2. Revisions DATE AUTHOUR DESCRIPTION 2012/12/03 Jiahe Jou Draft.
- 3. Outline ● Overview ● Pad Configuration ● Off Mode Control ● Wake Up Detection ● Power Optimization ● Configuration How To ● Case Study - Talos7
- 4. 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)
- 5. Overview ● Pad configuration register 2
- 6. 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
- 7. Pad Configuration ● Examples
- 8. Pad Configuration ● Pull selection ○ PULL (2 bits), 0b00 ~ 0b11 PULL Behavior 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
- 9. 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
- 11. Off Mode Control ● Off mode selected ○ PRM_DEVICE_OFF_CTRL[0] DEVICE_OFF_ENABLE ○ CONTROL_PADCONF_GLOBAL[31] FORCE_OFFMODE_ENABLE
- 12. Wake Up Dectection ● Wake up enabled ○ PRM_IO_PMCTRL[16]GLOBAL_WUEN
- 13. 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
- 15. 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
- 16. Pad Configuration ● Recommended configuration for unconnected pads
- 17. Pad Configuration ● Ball Characteristics
- 18. 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);
- 19. 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; };
- 20. Case Study - Talos7 {GPMC_AD0, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat0: eMMC_AD0 */ {GPMC_AD1, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat1: eMMC_AD1 */ {GPMC_AD2, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat2: eMMC_AD2 */ {GPMC_AD3, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat3: eMMC_AD3 */ {GPMC_AD4, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat4: eMMC_AD4 */ {GPMC_AD5, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat5: eMMC_AD5 */ {GPMC_AD6, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat6: eMMC_AD6 */ {GPMC_AD7, (PTU | IEN | OFF_EN | OFF_PD | OFF_IN | M1)}, /* sdmmc2_dat7: eMMC_AD7 */
- 21. Case Study - Talos7 {SDMMC1_DAT4, (PTD | IDIS | M7)}, /* sdmmc1_dat4: NC: SafeMode */ {SDMMC1_DAT5, (PTD | IDIS | M7)}, /* sdmmc1_dat5: NC: SafeMode */ {SDMMC1_DAT6, (PTD | IDIS | M7)}, /* sdmmc1_dat6: NC: SafeMode */ {SDMMC1_DAT7, (PTD | IDIS | M7)}, /* sdmmc1_dat7: NC: SafeMode */
- 22. Case Study - Talos7 omap_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); omap_mux_init_signal("sdmmc5_dat1", OMAP_PIN_INPUT_PULLUP); omap_mux_init_signal("sdmmc5_dat2", OMAP_PIN_INPUT_PULLUP); omap_mux_init_signal("sdmmc5_dat3", OMAP_PIN_INPUT_PULLUP);
- 23. Case Study - Talos7 static 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, } ... }
- 24. Q&A
- 25. The End