[PATCH] A generic RTC driver [1/3]

This is the current version of the genrtc driver from the m68k
community.  This is slightly different than the version I have sent
previously in that it has been switched to C99-style initializers,
which was done in the current m68k CVS tree by Geert Uytterhoeven, and
the needed changes to select/compile it in general.  I had previously
asked the m68k community if anyone objected to this being submitted by me,
and I got Richard Zidlicky's (who's at the top of the file) approval, as
well as Geert Uytterhoeven's approval.

drivers/char/Config.help

@@ -969,6 +969,31 @@ CONFIG_RTC
   The module is called rtc.o. If you want to compile it as a module,
   say M here and read <file:Documentation/modules.txt>.
 
+Generic Real Time Clock Support
+CONFIG_GEN_RTC
+  If you say Y here and create a character special file /dev/rtc with
+  major number 10 and minor number 135 using mknod ("man mknod"), you
+  will get access to the real time clock (or hardware clock) built
+  into your computer.
+
+  It reports status information via the file /proc/driver/rtc and its
+  behaviour is set by various ioctls on /dev/rtc. If you enable the
+  "extended RTC operation" below it will also provide an emulation
+  for RTC_UIE which is required by some programs and may improve
+  precision in some cases.
+
+  This driver is also available as a module ( = code which can be
+  inserted in and removed from the running kernel whenever you want).
+  The module is called genrtc.o. If you want to compile it as a module,
+  say M here and read <file:Documentation/modules.txt>. To load the
+  module automaticaly add 'alias char-major-10-135 genrtc' to your
+  /etc/modules.conf
+
+Extended RTC operation
+CONFIG_GEN_RTC_X
+  Provides an emulation for RTC_UIE which is required by some programs
+  and may improve precision of the generic RTC support in some cases.
+
 CONFIG_H8
   The Hitachi H8/337 is a microcontroller used to deal with the power
   and thermal environment. If you say Y here, you will be able to

drivers/char/Config.in

@@ -151,6 +151,12 @@ if [ "$CONFIG_X86" = "y" -o "$CONFIG_IA64" = "y" ]; then
 fi
 tristate '/dev/nvram support' CONFIG_NVRAM
 tristate 'Enhanced Real Time Clock Support' CONFIG_RTC
+if [ "$CONFIG_RTC" != "y" ]; then
+   tristate 'Generic /dev/rtc emulation' CONFIG_GEN_RTC      
+   if [ "$CONFIG_GEN_RTC" != "n" ]; then
+      bool '   Extended RTC operation' CONFIG_GEN_RTC_X
+   fi
+fi
 if [ "$CONFIG_IA64" = "y" ]; then
    bool 'EFI Real Time Clock Services' CONFIG_EFI_RTC
 fi

drivers/char/Makefile

@@ -167,6 +167,7 @@ obj-$(CONFIG_APPLICOM) += applicom.o
 obj-$(CONFIG_SONYPI) += sonypi.o
 obj-$(CONFIG_ATARIMOUSE) += atarimouse.o
 obj-$(CONFIG_RTC) += rtc.o
+obj-$(CONFIG_GEN_RTC) += genrtc.o
 obj-$(CONFIG_EFI_RTC) += efirtc.o
 ifeq ($(CONFIG_PPC),)
   obj-$(CONFIG_NVRAM) += nvram.o

include/linux/rtc.h

@@ -39,10 +39,32 @@ struct rtc_wkalrm {
 	struct rtc_time time;	/* time the alarm is set to */
 };
 
+/*
+ * Data structure to control PLL correction some better RTC feature
+ * pll_value is used to get or set current value of correction,
+ * the rest of the struct is used to query HW capabilities.
+ * This is modeled after the RTC used in Q40/Q60 computers but
+ * should be sufficiently flexible for other devices
+ *
+ * +ve pll_value means clock will run faster by
+ *   pll_value*pll_posmult/pll_clock
+ * -ve pll_value means clock will run slower by
+ *   pll_value*pll_negmult/pll_clock
+ */ 
+
+struct rtc_pll_info {
+	int pll_ctrl;       /* placeholder for fancier control */
+	int pll_value;      /* get/set correction value */
+	int pll_max;        /* max +ve (faster) adjustment value */
+	int pll_min;        /* max -ve (slower) adjustment value */
+	int pll_posmult;    /* factor for +ve corection */
+	int pll_negmult;    /* factor for -ve corection */
+	long pll_clock;     /* base PLL frequency */
+};
 
 /*
  * ioctl calls that are permitted to the /dev/rtc interface, if 
- * CONFIG_RTC/CONFIG_EFI_RTC was enabled.
+ * any of the RTC drivers are enabled.
  */
 
 #define RTC_AIE_ON	_IO('p', 0x01)	/* Alarm int. enable on		*/
@@ -65,6 +87,8 @@ struct rtc_wkalrm {
 
 #define RTC_WKALM_SET	_IOW('p', 0x0f, struct rtc_wkalrm)/* Set wakeup alarm*/
 #define RTC_WKALM_RD	_IOR('p', 0x10, struct rtc_wkalrm)/* Get wakeup alarm*/
+#define RTC_PLL_GET	_IOR('p', 0x11, struct rtc_pll_info)  /* Get PLL correction */
+#define RTC_PLL_SET	_IOW('p', 0x12, struct rtc_pll_info)  /* Set PLL correction */
 
 #ifdef __KERNEL__