rtc: class driver for ppc_md RTC functions

This hooks up the platform-specific [gs]et_rtc_time functions so that
kernels using CONFIG_RTC_CLASS have RTC support on most PowerPC platforms.

A new driver, and one which we've been shipping in Fedora for a while
already, since otherwise RTC support breaks.

[[e-mail]: fix Kconfig indenting]
Signed-off-by: David Woodhouse <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>
Acked-by: Alessandro Zummo <[e-mail]>
Acked-by: David Brownell <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/rtc/Kconfig

···
 	help
 	  If you say yes here you get support for the Ricoh RS5C313 RTC chips.
 
+config RTC_DRV_PPC
+       tristate "PowerPC machine dependent RTC support"
+       depends on PPC_MERGE
+       help
+	 The PowerPC kernel has machine-specific functions for accessing
+	 the RTC. This exposes that functionality through the generic RTC
+	 class.
+
 endif # RTC_CLASS

drivers/rtc/Makefile

···
 obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o
 obj-$(CONFIG_RTC_DRV_VR41XX)	+= rtc-vr41xx.o
 obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
+obj-$(CONFIG_RTC_DRV_PPC)	+= rtc-ppc.o

drivers/rtc/rtc-ppc.c

···
+/*
+ * RTC driver for ppc_md RTC functions
+ *
+ * © 2007 Red Hat, Inc.
+ *
+ * Author: David Woodhouse <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <asm/machdep.h>
+
+static int ppc_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	ppc_md.get_rtc_time(tm);
+	return 0;
+}
+
+static int ppc_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return ppc_md.set_rtc_time(tm);
+}
+
+static const struct rtc_class_ops ppc_rtc_ops = {
+	.set_time = ppc_rtc_set_time,
+	.read_time = ppc_rtc_read_time,
+};
+
+static struct rtc_device *rtc;
+static struct platform_device *ppc_rtc_pdev;
+
+static int __init ppc_rtc_init(void)
+{
+	if (!ppc_md.get_rtc_time || !ppc_md.set_rtc_time)
+		return -ENODEV;
+
+	ppc_rtc_pdev = platform_device_register_simple("ppc-rtc", 0, NULL, 0);
+	if (IS_ERR(ppc_rtc_pdev))
+		return PTR_ERR(ppc_rtc_pdev);
+
+	rtc = rtc_device_register("ppc_md", &ppc_rtc_pdev->dev,
+				  &ppc_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		platform_device_unregister(ppc_rtc_pdev);
+		return PTR_ERR(rtc);
+	}
+
+	return 0;
+}
+
+static void __exit ppc_rtc_exit(void)
+{
+	rtc_device_unregister(rtc);
+	platform_device_unregister(ppc_rtc_pdev);
+}
+
+module_init(ppc_rtc_init);
+module_exit(ppc_rtc_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Woodhouse <[e-mail]>");
+MODULE_DESCRIPTION("Generic RTC class driver for PowerPC");