arm: sunxi: add support for DIP detection to CHIP board

Add the extension_board_scan specific function to scan the information
of the EEPROM on one-wire and fill the extension struct.
Add the Kconfig symbol to enable the needs to detect DIPs.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Andre Przywara <andre.przywara@arm.com>

arch/arm/mach-sunxi/Kconfig

@@ -1089,3 +1089,12 @@ config BLUETOOTH_DT_DEVICE_FIXUP
 	  flipped elsewise.
 
 endif
+
+config CHIP_DIP_SCAN
+	bool "Enable DIPs detection for CHIP board"
+	select SUPPORT_EXTENSION_SCAN
+	select W1
+	select W1_GPIO
+	select W1_EEPROM
+	select W1_EEPROM_DS24XXX
+	select CMD_EXTENSION

board/sunxi/Makefile

@@ -11,3 +11,4 @@ obj-$(CONFIG_SUN7I_GMAC)	+= gmac.o
 obj-$(CONFIG_MACH_SUN4I)	+= dram_sun4i_auto.o
 obj-$(CONFIG_MACH_SUN5I)	+= dram_sun5i_auto.o
 obj-$(CONFIG_MACH_SUN7I)	+= dram_sun5i_auto.o
+obj-$(CONFIG_CHIP_DIP_SCAN)	+= chip.o

board/sunxi/chip.c

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2021
+ * Köry Maincent, Bootlin, <kory.maincent@bootlin.com>
+ * Based on initial code from Maxime Ripard
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <dm.h>
+#include <w1.h>
+#include <w1-eeprom.h>
+#include <dm/device-internal.h>
+
+#include <asm/arch/gpio.h>
+
+#include <extension_board.h>
+
+#define for_each_w1_device(b, d) \
+	for (device_find_first_child(b, d); *d; device_find_next_child(d))
+
+#define dip_convert(field)						\
+	(								\
+		(sizeof(field) == 1) ? field :				\
+		(sizeof(field) == 2) ? be16_to_cpu(field) :		\
+		(sizeof(field) == 4) ? be32_to_cpu(field) :		\
+		-1							\
+	)
+
+#define DIP_MAGIC	0x50494843	/* CHIP */
+
+struct dip_w1_header {
+	u32     magic;                  /* CHIP */
+	u8      version;                /* spec version */
+	u32     vendor_id;
+	u16     product_id;
+	u8      product_version;
+	char    vendor_name[32];
+	char    product_name[32];
+	u8      rsvd[36];               /* rsvd for future spec versions */
+	u8      data[16];               /* user data, per-dip specific */
+} __packed;
+
+int extension_board_scan(struct list_head *extension_list)
+{
+	struct extension *dip;
+	struct dip_w1_header w1_header;
+	struct udevice *bus, *dev;
+	u32 vid;
+	u16 pid;
+	int ret;
+
+	int num_dip = 0;
+
+	sunxi_gpio_set_pull(SUNXI_GPD(2), SUNXI_GPIO_PULL_UP);
+
+	ret = w1_get_bus(0, &bus);
+	if (ret) {
+		printf("one wire interface not found\n");
+		return 0;
+	}
+
+	for_each_w1_device(bus, &dev) {
+		if (w1_get_device_family(dev) != W1_FAMILY_DS2431)
+			continue;
+
+		ret = device_probe(dev);
+		if (ret) {
+			printf("Couldn't probe device %s: error %d",
+			       dev->name, ret);
+			continue;
+		}
+
+		w1_eeprom_read_buf(dev, 0, (u8 *)&w1_header, sizeof(w1_header));
+
+		if (w1_header.magic != DIP_MAGIC)
+			continue;
+
+		vid = dip_convert(w1_header.vendor_id);
+		pid = dip_convert(w1_header.product_id);
+
+		printf("DIP: %s (0x%x) from %s (0x%x)\n",
+		       w1_header.product_name, pid,
+		       w1_header.vendor_name, vid);
+
+		dip = calloc(1, sizeof(struct extension));
+		if (!dip) {
+			printf("Error in memory allocation\n");
+			return num_dip;
+		}
+
+		snprintf(dip->overlay, sizeof(dip->overlay), "dip-%x-%x.dtbo",
+			 vid, pid);
+		strncpy(dip->name, w1_header.product_name, 32);
+		strncpy(dip->owner, w1_header.vendor_name, 32);
+		list_add_tail(&dip->list, extension_list);
+		num_dip++;
+	}
+	return num_dip;
+}