W1-EEPROM: add sandbox driver

Add a sandbox driver for a one wire EEPROM memory

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

drivers/w1-eeprom/Kconfig

@@ -18,6 +18,12 @@ config W1_EEPROM_DS24XXX
 	help
 	  Maxim DS24 EEPROMs 1-Wire EEPROM support
 
+config W1_EEPROM_SANDBOX
+	bool "Enable sandbox onewire EEPROM driver"
+	depends on W1
+	help
+	  Sandbox driver for a onewire EEPROM memory
+
 endif
 
 endmenu

drivers/w1-eeprom/Makefile

@@ -2,3 +2,4 @@ obj-$(CONFIG_W1_EEPROM) += w1-eeprom-uclass.o
 
 obj-$(CONFIG_W1_EEPROM_DS24XXX) += ds24xxx.o
 
+obj-$(CONFIG_W1_EEPROM_SANDBOX) += eep_sandbox.o

drivers/w1-eeprom/eep_sandbox.c

@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier:	GPL-2.0+
+ *
+ * Copyright (c) 2018 Microchip Technology, Inc.
+ *
+ */
+
+#include <common.h>
+#include <linux/err.h>
+#include <dm.h>
+#include <w1-eeprom.h>
+#include <w1.h>
+
+#define W1_F2D_READ_EEPROM      0xf0
+
+#define EEP_SANDBOX_SAMPLE_MEM "this is a sample EEPROM memory string."
+
+static int eep_sandbox_read_buf(struct udevice *dev, unsigned int offset,
+				u8 *buf, unsigned int count)
+{
+	/* do not allow to copy more than our maximum sample string */
+	if (offset + count < strlen(EEP_SANDBOX_SAMPLE_MEM)) {
+		offset = 0;
+		count = strlen(EEP_SANDBOX_SAMPLE_MEM);
+	}
+	strncpy((char *)buf, EEP_SANDBOX_SAMPLE_MEM, count);
+
+	/*
+	 * in case the w1 subsystem uses some different kind of sandbox testing,
+	 * like randomized gpio values , we take the buffer from there
+	 */
+
+	w1_reset_select(dev);
+
+	w1_write_byte(dev, W1_F2D_READ_EEPROM);
+	w1_write_byte(dev, offset & 0xff);
+	w1_write_byte(dev, offset >> 8);
+
+	w1_read_buf(dev, buf, count);
+
+	/*
+	 * even if read buf from w1 fails, return success as we hardcoded
+	 * the buffer.
+	 */
+	return 0;
+}
+
+static const struct w1_eeprom_ops eep_sandbox_ops = {
+	.read_buf	= eep_sandbox_read_buf,
+};
+
+static const struct udevice_id eep_sandbox_id[] = {
+	{ .compatible = "sandbox,w1-eeprom", .data = W1_FAMILY_EEP_SANDBOX },
+	{ },
+};
+
+U_BOOT_DRIVER(eep_sandbox) = {
+	.name		= "eep_sandbox",
+	.id		= UCLASS_W1_EEPROM,
+	.of_match	= eep_sandbox_id,
+	.ops		= &eep_sandbox_ops,
+};

include/w1.h

@@ -12,6 +12,7 @@
 
 #define W1_FAMILY_DS24B33	0x23
 #define W1_FAMILY_DS2431	0x2d
+#define W1_FAMILY_EEP_SANDBOX	0xfe
 
 struct w1_device {
 	u64	id;