[PATCH] toradex: colibri_imx7: Enable nand/emmc detection and set boot variant

[Hiago De Franco <hiagofranco@gmail.com>]

From: Hiago De Franco <hiago.franco@toradex.com>

Add detection of eMMC vs NAND devices on the Colibri iMX7
board. A GPIO is configured to detect the presence of an on-board resistor
that is configured differently based on the flash memory used. Depending on
the detection result, the 'variant' environment variable is set to '-emmc'
or cleared, indicating the type of storage device.

This enhancement improves variant detection during system initialization
through USB recovery mode, where U-Boot is loaded directly to RAM. This
allows variant detection for an accurate device tree selection.

Signed-off-by: Hiago De Franco <hiago.franco@toradex.com>
---
 board/toradex/colibri_imx7/colibri_imx7.c | 24 +++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/board/toradex/colibri_imx7/colibri_imx7.c b/board/toradex/colibri_imx7/colibri_imx7.c
index 119e67b47f..f0356af008 100644
--- a/board/toradex/colibri_imx7/colibri_imx7.c
+++ b/board/toradex/colibri_imx7/colibri_imx7.c
@@ -53,6 +53,11 @@ DECLARE_GLOBAL_DATA_PTR;
 
 #define USB_CDET_GPIO	IMX_GPIO_NR(7, 14)
 
+#define FLASH_DETECTION_CTRL (PAD_CTL_HYS | PAD_CTL_PUE)
+#define FLASH_DET_GPIO IMX_GPIO_NR(6, 11)
+
+static bool is_emmc;
+
 int dram_init(void)
 {
 	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, imx_ddr_size());
@@ -60,6 +65,10 @@ int dram_init(void)
 	return 0;
 }
 
+static iomux_v3_cfg_t const flash_detection_pads[] = {
+	MX7D_PAD_SD3_RESET_B__GPIO6_IO11 | MUX_PAD_CTRL(FLASH_DETECTION_CTRL),
+};
+
 static iomux_v3_cfg_t const uart1_pads[] = {
 	MX7D_PAD_UART1_RX_DATA__UART1_DTE_TX | MUX_PAD_CTRL(UART_PAD_CTRL),
 	MX7D_PAD_UART1_TX_DATA__UART1_DTE_RX | MUX_PAD_CTRL(UART_PAD_CTRL),
@@ -183,6 +192,16 @@ int board_init(void)
 	/* address of boot parameters */
 	gd->bd->bi_boot_params = PHYS_SDRAM + 0x100;
 
+	/*
+	 * Enable GPIO on NAND_WE_B/eMMC_RST with 100k pull-down. eMMC_RST
+	 * is pulled high with 4.7k for eMMC devices. This allows to reliably
+	 * detect eMMC/NAND flash
+	 */
+	imx_iomux_v3_setup_multiple_pads(flash_detection_pads, ARRAY_SIZE(flash_detection_pads));
+	gpio_request(FLASH_DET_GPIO, "flash-detection-gpio");
+	is_emmc = gpio_get_value(FLASH_DET_GPIO);
+	gpio_free(FLASH_DET_GPIO);
+
 #ifdef CONFIG_FEC_MXC
 	setup_fec();
 #endif
@@ -348,6 +367,11 @@ int board_late_init(void)
 		env_set("bootcmd", "sdp 0");
 	}
 #endif
+	if (is_emmc)
+		env_set("variant", "-emmc");
+	else
+		env_set("variant", "");
+
 	return 0;
 }
 #endif /* CONFIG_BOARD_LATE_INIT */
-- 
2.40.1