xref: /openbmc/u-boot/doc/README.atmel_mci (revision 67cf22cb)
1How to use SD/MMC cards with Atmel SoCs having MCI hardware
2-----------------------------------------------------------
32010-08-16 Reinhard Meyer <reinhard.meyer@emk-elektronik.de>
4
5This is a new approach to use Atmel MCI hardware with the
6general MMC framework. Therefore it benefits from that
7framework's abilities to handle SDHC Cards and the ability
8to write blocks.
9
10- AT91SAM9XE512 (tested, will definitely work with XE128 and XE256)
11- AT91SAM9260 (not tested, but MCI is to AT91SAM9XE)
12- AT91SAM9G20 (not tested, should work)
13
14It should work with all other ATMEL devices that have MCI.
15
16The generic driver does NOT assign port pins to the MCI block
17nor does it start the MCI clock. This has to be handled in a
18board/SoC specific manner before the driver is initialized:
19
20example: this is added to at91sam9260_devices.c:
21
22#if defined(CONFIG_GENERIC_ATMEL_MCI)
23void at91_mci_hw_init(void)
24{
25	at91_set_a_periph(AT91_PIO_PORTA, 8, PUP);	/* MCCK */
26#if defined(CONFIG_ATMEL_MCI_PORTB)
27	at91_set_b_periph(AT91_PIO_PORTA, 1, PUP);	/* MCCDB */
28	at91_set_b_periph(AT91_PIO_PORTA, 0, PUP);	/* MCDB0 */
29	at91_set_b_periph(AT91_PIO_PORTA, 5, PUP);	/* MCDB1 */
30	at91_set_b_periph(AT91_PIO_PORTA, 4, PUP);	/* MCDB2 */
31	at91_set_b_periph(AT91_PIO_PORTA, 3, PUP);	/* MCDB3 */
32#else
33	at91_set_a_periph(AT91_PIO_PORTA, 7, PUP);	/* MCCDA */
34	at91_set_a_periph(AT91_PIO_PORTA, 6, PUP);	/* MCDA0 */
35	at91_set_a_periph(AT91_PIO_PORTA, 9, PUP);	/* MCDA1 */
36	at91_set_a_periph(AT91_PIO_PORTA, 10, PUP);	/* MCDA2 */
37	at91_set_a_periph(AT91_PIO_PORTA, 11, PUP);	/* MCDA3 */
38#endif
39}
40#endif
41
42the board specific file need added:
43...
44#ifdef CONFIG_GENERIC_ATMEL_MCI
45# include <mmc.h>
46#endif
47...
48#ifdef CONFIG_GENERIC_ATMEL_MCI
49/* this is a weak define that we are overriding */
50int board_mmc_init(bd_t *bd)
51{
52	/* Enable clock */
53	at91_sys_write(AT91_PMC_PCER, 1 << AT91SAM9260_ID_MCI);
54	at91_mci_hw_init();
55
56	/* This calls the atmel_mci_init in gen_atmel_mci.c */
57	return atmel_mci_init((void *)AT91_BASE_MCI);
58}
59
60/* this is a weak define that we are overriding */
61int board_mmc_getcd(struct mmc *mmc)
62{
63	return !at91_get_gpio_value(CONFIG_SYS_MMC_CD_PIN);
64}
65
66#endif
67
68and the board definition files needs:
69
70/* SD/MMC card */
71#define CONFIG_GENERIC_ATMEL_MCI	1
72#define CONFIG_ATMEL_MCI_PORTB		1	/* Atmel XE-EK uses port B */
73#define CONFIG_SYS_MMC_CD_PIN		AT91_PIN_PC9
74#define CONFIG_CMD_MMC			1
75