Porting to different the MMC interface

Author : Dicky Chiang
Date : Dec 2012

Introduce:
This document describes how to porting to a different the MMC interface.
All presentation will be based on the DM37x platform with Linux kernel 2.6.37 and NLCP WLAN driver.On Dm37x WLAN SDIO is connected to MMC2 bus. For example, the following will porting to MMC3 interface.

Step 1:
In file kernel/arch/arm/mach-omap2/board-omap3evm.c
Modify Initialization and pin-muxing if using any other MMC bus.
static struct omap2_hsmmc_info mmc[] = {
{
.mmc = 1,
.caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA,
.gpio_wp = 29,
},
#ifdef CONFIG_WL12XX_PLATFORM_DATA
{
.name = "wl1271",
.mmc = 3,
.caps = MMC_CAP_4_BIT_DATA | MMC_CAP_POWER_OFF_CARD,
.gpio_wp = -EINVAL,
.gpio_cd = -EINVAL,
.nonremovable = true,
},
#endif
{} /* Terminator */
};
static struct omap_board_mux board_mux[] __initdata = {
#ifdef CONFIG_WL12XX_PLATFORM_DATA
/* WLAN IRQ - GPIO 112 */
OMAP3_MUX(CSI2_DX0, OMAP_MUX_MODE4 | OMAP_PIN_INPUT),
/* WLAN POWER ENABLE - GPIO 16 */
OMAP3_MUX(ETK_D2, OMAP_MUX_MODE4 | OMAP_PIN_OUTPUT),
/* MMC3 SDIO pin muxes for WL12xx */
OMAP3_MUX(ETK_CLK, OMAP_MUX_MODE2 |
OMAP_PIN_INPUT_PULLUP),//CLK
OMAP3_MUX(ETK_CTL, OMAP_MUX_MODE2 |
OMAP_PIN_INPUT_PULLUP),//CMD
OMAP3_MUX(ETK_D3, OMAP_MUX_MODE2 |
OMAP_PIN_INPUT_PULLUP),//DATA3
OMAP3_MUX(ETK_D6, OMAP_MUX_MODE2 |
OMAP_PIN_INPUT_PULLUP),//DATA2
OMAP3_MUX(ETK_D5, OMAP_MUX_MODE2 |
OMAP_PIN_INPUT_PULLUP),//DATA1
OMAP3_MUX(ETK_D4, OMAP_MUX_MODE2 |
OMAP_PIN_INPUT_PULLUP),//DATA0
//USB gpio40
OMAP3_MUX(GPMC_A7, OMAP_MUX_MODE4 | OMAP_PIN_OUTPUT ),
#endif
{ .reg_offset = OMAP_MUX_TERMINATOR },
};

Modify regulator supply to register in kernel when the probe host MMC slot.
static struct regulator_consumer_supply panther_vmmc2_supply =
REGULATOR_SUPPLY("vmmc", "mmci-omap-hs.2")


Step 2.
In file kernel/arch/arm/mach-omap2/devices.c
Add to supported MMC3 host controller at omap2_mmc_mux func.
/* For MMC3 the pins need to be muxed in the board-*.c files */
if (controller_nr == 2) {
/* MMC3 */
omap_mux_init_signal("sdmmc3_clk",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_cmd",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_dat0",
OMAP_PIN_INPUT_PULLUP);
/*
* For 8 wire configurations, Lines DAT4, 5, 6 and 7 need to be muxed
* in the board-*.c files
*/
if (mmc_controller->slots[0].caps &
(MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA)) {
omap_mux_init_signal("sdmmc3_dat1",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_dat2",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_dat3",
OMAP_PIN_INPUT_PULLUP);
}
if (mmc_controller->slots[0].caps &
MMC_CAP_8_BIT_DATA) {
omap_mux_init_signal("sdmmc3_dat4.sdmmc3_dat4",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_dat5.sdmmc3_dat5",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_dat6.sdmmc3_dat6",
OMAP_PIN_INPUT_PULLUP);
omap_mux_init_signal("sdmmc3_dat7.sdmmc3_dat7",
OMAP_PIN_INPUT_PULLUP);
}
}


Step 3.
In file kernla/arch/arm/mach-omap2/mux34xx.c
Add the pin mux for support MMC3 interface. ( According the schematics and TRM)
static struct omap_mux __initdata omap3_muxmodes[] = {
……..
//MMC3_CLK
_OMAP3_MUXENTRY(ETK_CLK, 12,
"etk_clk", "mcbsp5_clkx", "sdmmc3_clk", "hsusb1_stp",
"gpio_12", "mm1_rxdp", "hsusb1_tll_stp", "hw_dbg0"),
//MMC3_CMD
_OMAP3_MUXENTRY(ETK_CTL, 13,
"etk_ctl", NULL, "sdmmc3_cmd", "hsusb1_clk",
"gpio_13", NULL, "hsusb1_tll_clk", "hw_dbg1"),
//MMC3_DATA0
_OMAP3_MUXENTRY(ETK_D4, 18,
"etk_d4", "mcbsp5_dr", "sdmmc3_data0", "hsusb1_data4",
"gpio_18", NULL, "hsusb1_tll_data4", "hw_dbg6"),
//MMC3_DATA1
_OMAP3_MUXENTRY(ETK_D5, 19,
"etk_d5", "mcbsp5_fsx", "sdmmc3_data1", "hsusb1_data5",
"gpio_19", NULL, "hsusb1_tll_data5", "hw_dbg7"),
//MMC3_DATA2
_OMAP3_MUXENTRY(ETK_D6, 20,
"etk_d6", "mcbsp5_dx", "sdmmc3_data2", "hsusb1_data6",
"gpio_20", NULL, "hsusb1_tll_data6", "hw_dbg8"),
//MMC3_DATA3
_OMAP3_MUXENTRY(ETK_D6, 17,
"etk_d3", "mcbspi3_clk", "sdmmc3_data3", "hsusb1_data7",
"gpio_17", NULL, "hsusb1_tll_data7", "hw_dbg5")
………..
}

Step 4.
In file u-boot/ti/evm/evm.h
Add the mux configuration for that pin at u-boot.
#define MUX_EVM() \
………
/* SDIO Interface to WIFI Module */ \
MUX_VAL(CP(ETK_CLK_ES2), (IEN | PTU | EN | M4)) /*MMC3_CLK*/\
MUX_VAL(CP(ETK_CTL_ES2), (IEN | PTU | EN | M4)) /*MMC3_CMD*/\
MUX_VAL(CP(ETK_D4_ES2), (IEN | PTU | EN | M4))/*MMC3_DATA0*/\
MUX_VAL(CP(ETK_D5_ES2), (IEN | PTU | EN | M4))/*MMC3_DATA1*/\
MUX_VAL(CP(ETK_D6_ES2), (IEN | PTU | EN | M4))/*MMC3_DATA2*/\
MUX_VAL(CP(ETK_D3_ES2), (IEN | PTU | EN | M4))/*MMC3_DATA3*/\
……..
#endif