dm: rtc: sandbox: Add an emulated I2C RTC device

Add a sandbox I2C emulation device which emulates a real-time clock. The
clock works off an offset from the current system time, and supports setting
and getting the clock, as well as access to byte-width regisers in the RTC.
It does not support changing the system time.

This device can be used for testing the 'date' command on sandbox, as well
as the RTC uclass.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/include/asm/rtc.h

@@ -0,0 +1,28 @@
+/*
+ * Simulate an I2C real time clock
+ *
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __asm_rtc_h
+#define __asm_rtc_h
+
+/* Register numbers in the sandbox RTC */
+enum {
+	REG_SEC		= 5,
+	REG_MIN,
+	REG_HOUR,
+	REG_MDAY,
+	REG_MON,
+	REG_YEAR,
+	REG_WDAY,
+
+	REG_RESET	= 0x20,
+
+	REG_COUNT	= 0x80,
+};
+
+#endif

arch/sandbox/include/asm/test.h

@@ -46,4 +46,25 @@ void sandbox_i2c_eeprom_set_offset_len(struct udevice *dev, int offset_len);
  */
 void sandbox_timer_add_offset(unsigned long offset);
 
+/**
+ * sandbox_i2c_rtc_set_offset() - set the time offset from system/base time
+ *
+ * @dev:		RTC device to adjust
+ * @use_system_time:	true to use system time, false to use @base_time
+ * @offset:		RTC offset from current system/base time (-1 for no
+ *			change)
+ * @return old value of RTC offset
+ */
+long sandbox_i2c_rtc_set_offset(struct udevice *dev, bool use_system_time,
+				int offset);
+
+/**
+ * sandbox_i2c_rtc_get_set_base_time() - get and set the base time
+ *
+ * @dev:		RTC device to adjust
+ * @base_time:		New base system time (set to -1 for no change)
+ * @return old base time
+ */
+long sandbox_i2c_rtc_get_set_base_time(struct udevice *dev, long base_time);
+
 #endif

drivers/rtc/Makefile

@@ -26,6 +26,7 @@ obj-$(CONFIG_RTC_DS164x) += ds164x.o
 obj-$(CONFIG_RTC_DS174x) += ds174x.o
 obj-$(CONFIG_RTC_DS3231) += ds3231.o
 obj-$(CONFIG_RTC_FTRTC010) += ftrtc010.o
+obj-$(CONFIG_SANDBOX) += i2c_rtc_emul.o
 obj-$(CONFIG_RTC_IMXDI) += imxdi.o
 obj-$(CONFIG_RTC_ISL1208) += isl1208.o
 obj-$(CONFIG_RTC_M41T11) += m41t11.o

drivers/rtc/i2c_rtc_emul.c

@@ -0,0 +1,236 @@
+/*
+ * Simulate an I2C real time clock
+ *
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+/*
+ * This is a test driver. It starts off with the current time of the machine,
+ * but also supports setting the time, using an offset from the current
+ * clock. This driver is only intended for testing, not accurate
+ * time-keeping. It does not change the system time.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <os.h>
+#include <rtc.h>
+#include <asm/rtc.h>
+#include <asm/test.h>
+
+#ifdef DEBUG
+#define debug_buffer print_buffer
+#else
+#define debug_buffer(x, ...)
+#endif
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/**
+ * struct sandbox_i2c_rtc_plat_data - platform data for the RTC
+ *
+ * @base_time:		Base system time when RTC device was bound
+ * @offset:		RTC offset from current system time
+ * @use_system_time:	true to use system time, false to use @base_time
+ * @reg:		Register values
+ */
+struct sandbox_i2c_rtc_plat_data {
+	long base_time;
+	long offset;
+	bool use_system_time;
+	u8 reg[REG_COUNT];
+};
+
+struct sandbox_i2c_rtc {
+	unsigned int offset_secs;
+};
+
+long sandbox_i2c_rtc_set_offset(struct udevice *dev, bool use_system_time,
+				int offset)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(dev);
+	long old_offset;
+
+	old_offset = plat->offset;
+	plat->use_system_time = use_system_time;
+	if (offset != -1)
+		plat->offset = offset;
+
+	return old_offset;
+}
+
+long sandbox_i2c_rtc_get_set_base_time(struct udevice *dev, long base_time)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(dev);
+	long old_base_time;
+
+	old_base_time = plat->base_time;
+	if (base_time != -1)
+		plat->base_time = base_time;
+
+	return old_base_time;
+}
+
+static void reset_time(struct udevice *dev)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(dev);
+	struct rtc_time now;
+
+	os_localtime(&now);
+	plat->base_time = rtc_mktime(&now);
+	plat->offset = 0;
+	plat->use_system_time = true;
+}
+
+static int sandbox_i2c_rtc_get(struct udevice *dev, struct rtc_time *time)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(dev);
+	struct rtc_time tm_now;
+	long now;
+
+	if (plat->use_system_time) {
+		os_localtime(&tm_now);
+		now = rtc_mktime(&tm_now);
+	} else {
+		now = plat->base_time;
+	}
+
+	return rtc_to_tm(now + plat->offset, time);
+}
+
+static int sandbox_i2c_rtc_set(struct udevice *dev, const struct rtc_time *time)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(dev);
+	struct rtc_time tm_now;
+	long now;
+
+	if (plat->use_system_time) {
+		os_localtime(&tm_now);
+		now = rtc_mktime(&tm_now);
+	} else {
+		now = plat->base_time;
+	}
+	plat->offset = rtc_mktime(time) - now;
+
+	return 0;
+}
+
+/* Update the current time in the registers */
+static int sandbox_i2c_rtc_prepare_read(struct udevice *emul)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(emul);
+	struct rtc_time time;
+	int ret;
+
+	ret = sandbox_i2c_rtc_get(emul, &time);
+	if (ret)
+		return ret;
+
+	plat->reg[REG_SEC] = time.tm_sec;
+	plat->reg[REG_MIN] = time.tm_min;
+	plat->reg[REG_HOUR] = time.tm_hour;
+	plat->reg[REG_MDAY] = time.tm_mday;
+	plat->reg[REG_MON] = time.tm_mon;
+	plat->reg[REG_YEAR] = time.tm_year - 1900;
+	plat->reg[REG_WDAY] = time.tm_wday;
+
+	return 0;
+}
+
+static int sandbox_i2c_rtc_complete_write(struct udevice *emul)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(emul);
+	struct rtc_time time;
+	int ret;
+
+	time.tm_sec = plat->reg[REG_SEC];
+	time.tm_min = plat->reg[REG_MIN];
+	time.tm_hour = plat->reg[REG_HOUR];
+	time.tm_mday = plat->reg[REG_MDAY];
+	time.tm_mon = plat->reg[REG_MON];
+	time.tm_year = plat->reg[REG_YEAR] + 1900;
+	time.tm_wday = plat->reg[REG_WDAY];
+
+	ret = sandbox_i2c_rtc_set(emul, &time);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int sandbox_i2c_rtc_xfer(struct udevice *emul, struct i2c_msg *msg,
+				int nmsgs)
+{
+	struct sandbox_i2c_rtc_plat_data *plat = dev_get_platdata(emul);
+	uint offset = 0;
+	int ret;
+
+	debug("\n%s\n", __func__);
+	ret = sandbox_i2c_rtc_prepare_read(emul);
+	if (ret)
+		return ret;
+	for (; nmsgs > 0; nmsgs--, msg++) {
+		int len;
+		u8 *ptr;
+
+		len = msg->len;
+		debug("   %s: msg->len=%d",
+		      msg->flags & I2C_M_RD ? "read" : "write",
+		      msg->len);
+		if (msg->flags & I2C_M_RD) {
+			debug(", offset %x, len %x: ", offset, len);
+
+			/* Read the register */
+			memcpy(msg->buf, plat->reg + offset, len);
+			memset(msg->buf + len, '\xff', msg->len - len);
+			debug_buffer(0, msg->buf, 1, msg->len, 0);
+		} else if (len >= 1) {
+			ptr = msg->buf;
+			offset = *ptr++ & (REG_COUNT - 1);
+			len--;
+			debug(", set offset %x: ", offset);
+			debug_buffer(0, msg->buf, 1, msg->len, 0);
+
+			/* Write the register */
+			memcpy(plat->reg + offset, ptr, len);
+			if (offset == REG_RESET)
+				reset_time(emul);
+		}
+	}
+	ret = sandbox_i2c_rtc_complete_write(emul);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+struct dm_i2c_ops sandbox_i2c_rtc_emul_ops = {
+	.xfer = sandbox_i2c_rtc_xfer,
+};
+
+static int sandbox_i2c_rtc_bind(struct udevice *dev)
+{
+	reset_time(dev);
+
+	return 0;
+}
+
+static const struct udevice_id sandbox_i2c_rtc_ids[] = {
+	{ .compatible = "sandbox,i2c-rtc" },
+	{ }
+};
+
+U_BOOT_DRIVER(sandbox_i2c_rtc_emul) = {
+	.name		= "sandbox_i2c_rtc_emul",
+	.id		= UCLASS_I2C_EMUL,
+	.of_match	= sandbox_i2c_rtc_ids,
+	.bind		= sandbox_i2c_rtc_bind,
+	.priv_auto_alloc_size = sizeof(struct sandbox_i2c_rtc),
+	.platdata_auto_alloc_size = sizeof(struct sandbox_i2c_rtc_plat_data),
+	.ops		= &sandbox_i2c_rtc_emul_ops,
+};