summaryrefslogtreecommitdiff
path: root/doc/README.atmel_mci
diff options
context:
space:
mode:
authorWolfgang Denk <wd@denx.de>2010-09-09 21:39:46 +0200
committerWolfgang Denk <wd@denx.de>2010-09-09 21:39:46 +0200
commit8fea51a4acb0c7da6fb375c9a708c50c0a1b66ad (patch)
treef6a3d36e35f8f4d1009c367417e918c210b0baf0 /doc/README.atmel_mci
parent40e74c852b76accfe27d832f23ea3020352bc120 (diff)
parentec99d983418897b120409f71712d41c01a21bf7c (diff)
downloadu-boot-imx-8fea51a4acb0c7da6fb375c9a708c50c0a1b66ad.zip
u-boot-imx-8fea51a4acb0c7da6fb375c9a708c50c0a1b66ad.tar.gz
u-boot-imx-8fea51a4acb0c7da6fb375c9a708c50c0a1b66ad.tar.bz2
Merge branch 'master' of git://git.denx.de/u-boot-arm
Diffstat (limited to 'doc/README.atmel_mci')
-rw-r--r--doc/README.atmel_mci86
1 files changed, 86 insertions, 0 deletions
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
+