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| -rw-r--r-- | doc/README.atmel_mci | 86 |
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diff --git a/doc/README.atmel_mci b/doc/README.atmel_mci new file mode 100644 index 0000000..18b1bdf --- /dev/null +++ b/doc/README.atmel_mci @@ -0,0 +1,86 @@ +How to use SD/MMC cards with Atmel SoCs having MCI hardware +----------------------------------------------------------- +2010-08-16 Reinhard Meyer <reinhard.meyer@emk-elektronik.de> + +This is a new approach to use Atmel MCI hardware with the +general MMC framework. Therefore it benefits from that +framework's abilities to handle SDHC Cards and the ability +to write blocks. + +- AT91SAM9XE512 (tested, will definitely work with XE128 and XE256) +- AT91SAM9260 (not tested, but MCI is to AT91SAM9XE) +- AT91SAM9G20 (not tested, should work) + +It should work with all other ATMEL devices that have MCI, +including AVR32. + +The generic driver does NOT assign port pins to the MCI block +nor does it start the MCI clock. This has to be handled in a +board/SoC specific manner before the driver is initialized: + +example: this is added to at91sam9260_devices.c: + +#if defined(CONFIG_ATMEL_MCI) || defined(CONFIG_GENERIC_ATMEL_MCI) +void at91_mci_hw_init(void) +{ + at91_set_a_periph(AT91_PIO_PORTA, 8, PUP); /* MCCK */ +#if defined(CONFIG_ATMEL_MCI_PORTB) + at91_set_b_periph(AT91_PIO_PORTA, 1, PUP); /* MCCDB */ + at91_set_b_periph(AT91_PIO_PORTA, 0, PUP); /* MCDB0 */ + at91_set_b_periph(AT91_PIO_PORTA, 5, PUP); /* MCDB1 */ + at91_set_b_periph(AT91_PIO_PORTA, 4, PUP); /* MCDB2 */ + at91_set_b_periph(AT91_PIO_PORTA, 3, PUP); /* MCDB3 */ +#else + at91_set_a_periph(AT91_PIO_PORTA, 7, PUP); /* MCCDA */ + at91_set_a_periph(AT91_PIO_PORTA, 6, PUP); /* MCDA0 */ + at91_set_a_periph(AT91_PIO_PORTA, 9, PUP); /* MCDA1 */ + at91_set_a_periph(AT91_PIO_PORTA, 10, PUP); /* MCDA2 */ + at91_set_a_periph(AT91_PIO_PORTA, 11, PUP); /* MCDA3 */ +#endif +} +#endif + +the board specific file need added: +... +#ifdef CONFIG_GENERIC_ATMEL_MCI +# include <mmc.h> +#endif +... +#ifdef CONFIG_GENERIC_ATMEL_MCI +/* this is a weak define that we are overriding */ +int board_mmc_init(bd_t *bd) +{ + /* Enable clock */ + at91_sys_write(AT91_PMC_PCER, 1 << AT91SAM9260_ID_MCI); + at91_mci_hw_init(); + + /* This calls the atmel_mci_init in gen_atmel_mci.c */ + return atmel_mci_init((void *)AT91_BASE_MCI); +} + +/* this is a weak define that we are overriding */ +int board_mmc_getcd(u8 *cd, struct mmc *mmc) +{ + /* + * the only currently existing use of this function + * (fsl_esdhc.c) suggests this function must return + * *cs = TRUE if a card is NOT detected -> in most + * cases the value of the pin when the detect switch + * closes to GND + */ + *cd = at91_get_gpio_value (CONFIG_SYS_MMC_CD_PIN) ? 1 : 0; + return 0; +} + +#endif + +and the board definition files needs: + +/* SD/MMC card */ +#define CONFIG_MMC 1 +#define CONFIG_GENERIC_MMC 1 +#define CONFIG_GENERIC_ATMEL_MCI 1 +#define CONFIG_ATMEL_MCI_PORTB 1 /* Atmel XE-EK uses port B */ +#define CONFIG_SYS_MMC_CD_PIN AT91_PIN_PC9 +#define CONFIG_CMD_MMC 1 + |