x86, olpc: Add XO-1 RTC driver

Add a driver to configure the XO-1 RTC via CS5536 MSRs, to be used as a
system wakeup source via olpc-xo1-pm.

Device detection is based on finding the relevant device tree node.

Signed-off-by: Daniel Drake <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Acked-by: Andres Salomon <[e-mail]>
Acked-by: Grant Likely <[e-mail]>
Reviewed-by: Sebastian Andrzej Siewior <[e-mail]>
Cc: [e-mail]
Signed-off-by: H. Peter Anvin <[e-mail]>

Documentation/devicetree/bindings/rtc/olpc-xo1-rtc.txt

···
+OLPC XO-1 RTC
+~~~~~~~~~~~~~
+
+Required properties:
+ - compatible : "olpc,xo1-rtc"

arch/x86/Kconfig

···
 	---help---
 	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
 
+config OLPC_XO1_RTC
+	bool "OLPC XO-1 Real Time Clock"
+	depends on OLPC_XO1_PM && RTC_DRV_CMOS
+	---help---
+	  Add support for the XO-1 real time clock, which can be used as a
+	  programmable wakeup source.
+
 config OLPC_XO1_SCI
 	bool "OLPC XO-1 SCI extras"
 	depends on OLPC && OLPC_XO1_PM && POWER_SUPPLY

arch/x86/platform/olpc/Makefile

···
 obj-$(CONFIG_OLPC)		+= olpc.o olpc_ofw.o olpc_dt.o
 obj-$(CONFIG_OLPC_XO1_PM)		+= olpc-xo1-pm.o xo1-wakeup.o
+obj-$(CONFIG_OLPC_XO1_RTC)	+= olpc-xo1-rtc.o
 obj-$(CONFIG_OLPC_XO1_SCI)	+= olpc-xo1-sci.o

arch/x86/platform/olpc/olpc-xo1-rtc.c

···
+/*
+ * Support for OLPC XO-1 Real Time Clock (RTC)
+ *
+ * Copyright (C) 2011 One Laptop per Child
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/mc146818rtc.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+
+#include <asm/msr.h>
+#include <asm/olpc.h>
+
+static void rtc_wake_on(struct device *dev)
+{
+	olpc_xo1_pm_wakeup_set(CS5536_PM_RTC);
+}
+
+static void rtc_wake_off(struct device *dev)
+{
+	olpc_xo1_pm_wakeup_clear(CS5536_PM_RTC);
+}
+
+static struct resource rtc_platform_resource[] = {
+	[0] = {
+		.start	= RTC_PORT(0),
+		.end	= RTC_PORT(1),
+		.flags	= IORESOURCE_IO,
+	},
+	[1] = {
+		.start	= RTC_IRQ,
+		.end	= RTC_IRQ,
+		.flags	= IORESOURCE_IRQ,
+	}
+};
+
+static struct cmos_rtc_board_info rtc_info = {
+	.rtc_day_alarm = 0,
+	.rtc_mon_alarm = 0,
+	.rtc_century = 0,
+	.wake_on = rtc_wake_on,
+	.wake_off = rtc_wake_off,
+};
+
+static struct platform_device xo1_rtc_device = {
+	.name = "rtc_cmos",
+	.id = -1,
+	.num_resources = ARRAY_SIZE(rtc_platform_resource),
+	.dev.platform_data = &rtc_info,
+	.resource = rtc_platform_resource,
+};
+
+static int __init xo1_rtc_init(void)
+{
+	int r;
+	struct device_node *node;
+
+	node = of_find_compatible_node(NULL, NULL, "olpc,xo1-rtc");
+	if (!node)
+		return 0;
+	of_node_put(node);
+
+	pr_info("olpc-xo1-rtc: Initializing OLPC XO-1 RTC\n");
+	rdmsrl(MSR_RTC_DOMA_OFFSET, rtc_info.rtc_day_alarm);
+	rdmsrl(MSR_RTC_MONA_OFFSET, rtc_info.rtc_mon_alarm);
+	rdmsrl(MSR_RTC_CEN_OFFSET, rtc_info.rtc_century);
+
+	r = platform_device_register(&xo1_rtc_device);
+	if (r)
+		return r;
+
+	device_init_wakeup(&xo1_rtc_device.dev, 1);
+	return 0;
+}
+arch_initcall(xo1_rtc_init);

include/linux/cs5535.h

···
 #define MSR_MFGPT_NR		0x51400029
 #define MSR_MFGPT_SETUP		0x5140002B
 
+#define MSR_RTC_DOMA_OFFSET	0x51400055
+#define MSR_RTC_MONA_OFFSET	0x51400056
+#define MSR_RTC_CEN_OFFSET	0x51400057
+
 #define MSR_LX_SPARE_MSR	0x80000011	/* DC-specific */
 
 #define MSR_GX_GLD_MSR_CONFIG	0xC0002001
···
 
 /* CS5536_PM1_EN bits */
 #define CS5536_PM_PWRBTN	(1 << 8)
+#define CS5536_PM_RTC		(1 << 10)
 
 /* CS5536_PM_GPE0_STS bits */
 #define CS5536_GPIOM7_PME_FLAG	(1 << 31)