board: ti: am62x: Add daughter card detection support

Add support to probe connected daughter cards, select
appropriate overlays for kernel boot up based on add-on
cards detected.

Signed-off-by: Nitin Yadav <n-yadav@ti.com>

board/ti/am62x/evm.c

@@ -19,11 +19,29 @@
 #include <asm/io.h>
 #include <asm/arch/hardware.h>
 #include <dm/uclass.h>
+#include <net.h>
+#include <asm/gpio.h>
+#include <cpu_func.h>
 
 #include "../common/board_detect.h"
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#define AM62X_MAX_DAUGHTER_CARDS	8
+
+/* Daughter card presence detection signals */
+enum {
+	AM62X_LPSK_HSE_BRD_DET,
+	AM62X_LPSK_BRD_DET_COUNT,
+};
+
+#if !defined(CONFIG_SPL_BUILD) && defined(CONFIG_ARM64)
+static struct gpio_desc board_det_gpios[AM62X_LPSK_BRD_DET_COUNT];
+#endif
+
+/* Max number of MAC addresses that are parsed/processed per daughter card */
+#define DAUGHTER_CARD_NO_OF_MAC_ADDR	8
+
 #define board_is_am62x_skevm()  (board_ti_k3_is("AM62-SKEVM") || \
 				 board_ti_k3_is("AM62B-SKEVM"))
 #define board_is_am62x_lp_skevm()  board_ti_k3_is("AM62-LP-SKEVM")
@@ -267,6 +285,153 @@ static void setup_serial(void)
 	env_set("serial#", serial_string);
 }
 
+#if !defined(CONFIG_SPL_BUILD) && defined(CONFIG_ARM64)
+static const char *k3_dtbo_list[AM62X_MAX_DAUGHTER_CARDS] = {NULL};
+
+static int init_daughtercard_det_gpio(char *gpio_name, struct gpio_desc *desc)
+{
+	int ret;
+
+	memset(desc, 0, sizeof(*desc));
+	ret = dm_gpio_lookup_name(gpio_name, desc);
+	if (ret < 0) {
+		pr_err("Failed to lookup gpio %s: %d\n", gpio_name, ret);
+		return ret;
+	}
+
+	/* Request GPIO, simply re-using the name as label */
+	ret = dm_gpio_request(desc, gpio_name);
+	if (ret < 0) {
+		pr_err("Failed to request gpio %s: %d\n", gpio_name, ret);
+		return ret;
+	}
+
+	return dm_gpio_set_dir_flags(desc, GPIOD_IS_IN);
+}
+
+static int probe_daughtercards(void)
+{
+	struct ti_am6_eeprom ep;
+	char mac_addr[DAUGHTER_CARD_NO_OF_MAC_ADDR][TI_EEPROM_HDR_ETH_ALEN];
+	u8 mac_addr_cnt;
+	char name_overlays[1024] = { 0 };
+	int i, nb_dtbos = 0;
+	int ret;
+
+	/*
+	 * Daughter card presence detection signal name to GPIO (via I2C I/O
+	 * expander @ address 0x53) name and EEPROM I2C address mapping.
+	 */
+	const struct {
+		char *gpio_name;
+		u8 i2c_addr;
+	} slot_map[AM62X_LPSK_BRD_DET_COUNT] = {
+		{ "gpio@22_2", 0x53, },	/* AM62X_LPSK_HSE_BRD_DET */
+	};
+
+	/* Declaration of daughtercards to probe */
+	const struct {
+		u8 slot_index;		/* Slot the card is installed */
+		char *card_name;	/* EEPROM-programmed card name */
+		char *dtbo_name;	/* Device tree overlay to apply */
+		u8 eth_offset;		/* ethXaddr MAC address index offset */
+	} cards[] = {
+		{
+			AM62X_LPSK_HSE_BRD_DET,
+			"SK-NAND-DC01",
+			"k3-am62x-lp-sk-nand.dtbo",
+			0,
+		},
+	};
+
+	/*
+	 * Initialize GPIO used for daughtercard slot presence detection and
+	 * keep the resulting handles in local array for easier access.
+	 */
+	for (i = 0; i < AM62X_LPSK_BRD_DET_COUNT; i++) {
+		ret = init_daughtercard_det_gpio(slot_map[i].gpio_name,
+						 &board_det_gpios[i]);
+		if (ret < 0)
+			return ret;
+	}
+
+	memset(k3_dtbo_list, 0, sizeof(k3_dtbo_list));
+	for (i = 0; i < ARRAY_SIZE(cards); i++) {
+		/* Obtain card-specific slot index and associated I2C address */
+		u8 slot_index = cards[i].slot_index;
+		u8 i2c_addr = slot_map[slot_index].i2c_addr;
+		const char *dtboname;
+
+		/*
+		 * The presence detection signal is active-low, hence skip
+		 * over this card slot if anything other than 0 is returned.
+		 */
+		ret = dm_gpio_get_value(&board_det_gpios[slot_index]);
+		if (ret < 0)
+			return ret;
+		else if (ret)
+			continue;
+
+		/* Get and parse the daughter card EEPROM record */
+		ret = ti_i2c_eeprom_am6_get(CONFIG_EEPROM_BUS_ADDRESS, i2c_addr,
+					    &ep,
+					    (char **)mac_addr,
+					    DAUGHTER_CARD_NO_OF_MAC_ADDR,
+					    &mac_addr_cnt);
+
+		if (ret) {
+			pr_err("Reading daughtercard EEPROM at 0x%02x failed %d\n",
+			       i2c_addr, ret);
+			/*
+			 * Even this is pretty serious let's just skip over
+			 * this particular daughtercard, rather than ending
+			 * the probing process altogether.
+			 */
+			continue;
+		}
+
+		/* Only process the parsed data if we found a match */
+		if (strncmp(ep.name, cards[i].card_name, sizeof(ep.name)))
+			continue;
+		printf("Detected: %s rev %s\n", ep.name, ep.version);
+
+		int j;
+
+		for (j = 0; j < mac_addr_cnt; j++) {
+			if (!is_valid_ethaddr((u8 *)mac_addr[j]))
+				continue;
+
+			eth_env_set_enetaddr_by_index("eth",
+						      cards[i].eth_offset + j,
+						      (uchar *)mac_addr[j]);
+		}
+		/* Skip if no overlays are to be added */
+		if (!strlen(cards[i].dtbo_name))
+			continue;
+
+		dtboname = cards[i].dtbo_name;
+		k3_dtbo_list[nb_dtbos++] = dtboname;
+
+		/*
+		 * Make sure we are not running out of buffer space by checking
+		 * if we can fit the new overlay, a trailing space to be used
+		 * as a separator, plus the terminating zero.
+		 */
+		if (strlen(name_overlays) + strlen(dtboname) + 2 >
+		    sizeof(name_overlays))
+			return -ENOMEM;
+
+		/* Append to our list of overlays */
+		strcat(name_overlays, dtboname);
+		strcat(name_overlays, " ");
+	}
+	/* Apply device tree overlay(s) to the U-Boot environment, if any */
+	if (strlen(name_overlays))
+		return env_set("name_overlays", name_overlays);
+	return 0;
+}
+#endif
+
 int board_late_init(void)
 {
 	if (IS_ENABLED(CONFIG_TI_I2C_BOARD_DETECT)) {
@@ -281,6 +446,12 @@ int board_late_init(void)
 		 * an index of 1.
 		 */
 		board_ti_am6_set_ethaddr(1, ep->mac_addr_cnt);
+
+#if !defined(CONFIG_SPL_BUILD) && defined(CONFIG_ARM64)
+		/* Check for and probe any plugged-in daughtercards */
+		if (board_is_am62x_lp_skevm())
+			probe_daughtercards();
+#endif
 	}
 
 	return 0;