board: atmel: add support for pda detection

This adds the support for PDA detection as common code for
Atmel boards.
Using the one wire interface over GPIO , an EEPROM memory is read
and compared to preprogrammed values for PDA screens TM4300, TM7000
and TM7000B.
Once the PDA is detected, an environment variable is set accordingly.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

board/atmel/common/board.c

@@ -5,7 +5,64 @@
  */
 
 #include <common.h>
+#include <w1.h>
+#include <w1-eeprom.h>
+#include <dm/device-internal.h>
+
+#define AT91_PDA_EEPROM_ID_OFFSET		15
+#define AT91_PDA_EEPROM_ID_LENGTH		5
+#define AT91_PDA_EEPROM_DEFAULT_BUS		0
 
 void dummy(void)
 {
 }
+
+#if defined CONFIG_W1
+void at91_pda_detect(void)
+{
+	struct udevice *bus, *dev;
+	u8 buf[AT91_PDA_EEPROM_ID_LENGTH + 1] = {0};
+	int ret;
+	int pda = 0;
+
+	ret = w1_get_bus(AT91_PDA_EEPROM_DEFAULT_BUS, &bus);
+	if (ret)
+		return;
+
+	for (device_find_first_child(bus, &dev);
+	     dev;
+	     device_find_next_child(&dev)) {
+		ret = device_probe(dev);
+		if (ret) {
+			continue;
+		} else {
+			ret = w1_eeprom_read_buf(dev, AT91_PDA_EEPROM_ID_OFFSET,
+						 (u8 *)buf, AT91_PDA_EEPROM_ID_LENGTH);
+			if (ret)
+				return;
+			break;
+		}
+	}
+	pda = simple_strtoul((const char *)buf, NULL, 10);
+
+	switch (pda) {
+	case 7000:
+		if (buf[4] == 'B')
+			printf("PDA TM7000B detected\n");
+		else
+			printf("PDA TM7000 detected\n");
+		break;
+	case 4300:
+		printf("PDA TM4300 detected\n");
+		break;
+	case 5000:
+		printf("PDA TM5000 detected\n");
+		break;
+	}
+	env_set("pda", (const char *)buf);
+}
+#else
+void at91_pda_detect(void)
+{
+}
+#endif