Add /dev/rtc support for Acorn machines.

drivers/acorn/char/i2c.c

@@ -14,6 +14,9 @@
  */
 #include <linux/init.h>
 #include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/miscdevice.h>
+#include <linux/rtc.h>
 #include <linux/i2c.h>
 #include <linux/i2c-algo-bit.h>
 
@@ -21,15 +24,19 @@
 #include <asm/io.h>
 #include <asm/hardware/ioc.h>
 #include <asm/system.h>
+#include <asm/uaccess.h>
 
 #include "pcf8583.h"
 
-extern unsigned long
-mktime(unsigned int year, unsigned int mon, unsigned int day,
-       unsigned int hour, unsigned int min, unsigned int sec);
 extern int (*set_rtc)(void);
 
 static struct i2c_client *rtc_client;
+static const unsigned char days_in_mon[] = 
+	{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+static unsigned int rtc_epoch = 1900;
+
+#define CMOS_CHECKSUM	(63)
+#define CMOS_YEAR	(64 + 128)
 
 static inline int rtc_command(int cmd, void *data)
 {
@@ -44,12 +51,10 @@ static inline int rtc_command(int cmd, void *data)
 /*
  * Read the current RTC time and date, and update xtime.
  */
-static void get_rtc_time(void)
+static void get_rtc_time(struct rtc_tm *rtctm, unsigned int *year)
 {
-	unsigned char ctrl;
-	unsigned char year;
-	struct rtc_tm rtctm;
-	struct mem rtcmem = { 0xc0, 1, &year };
+	unsigned char ctrl, yr[2];
+	struct mem rtcmem = { CMOS_YEAR, sizeof(yr), yr };
 
 	/*
 	 * Ensure that the RTC is running.
@@ -73,22 +78,53 @@ static void get_rtc_time(void)
 	if (rtc_command(MEM_READ, &rtcmem))
 		return;
 
-	if (rtc_command(RTC_GETDATETIME, &rtctm))
+	if (rtc_command(RTC_GETDATETIME, rtctm))
 		return;
 
-	if (year < 70)
-		year += 100;
+	*year = yr[1] * 100 + yr[0];
+}
 
-	xtime.tv_usec = rtctm.cs * 10000;
-	xtime.tv_sec  = mktime(1900 + year, rtctm.mon, rtctm.mday,
-			       rtctm.hours, rtctm.mins, rtctm.secs);
+static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year)
+{
+	unsigned char yr[2], leap, chk;
+	struct mem cmos_year  = { CMOS_YEAR, sizeof(yr), yr };
+	struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
+	int ret;
+
+	leap = (!(year % 4) && (year % 100)) || !(year % 400);
+
+	if (rtctm->mon > 12 || rtctm->mday == 0)
+		return -EINVAL;
+
+	if (rtctm->mday > (days_in_mon[rtctm->mon] + (rtctm->mon == 2 && leap)))
+		return -EINVAL;
+
+	if (rtctm->hours >= 24 || rtctm->mins >= 60 || rtctm->secs >= 60)
+		return -EINVAL;
+
+	ret = rtc_command(RTC_SETDATETIME, rtctm);
+	if (ret == 0) {
+		rtc_command(MEM_READ, &cmos_check);
+		rtc_command(MEM_READ, &cmos_year);
+
+		chk -= yr[1] + yr[0];
+
+		yr[1] = year / 100;
+		yr[0] = year % 100;
+
+		chk += yr[1] + yr[0];
+
+		rtc_command(MEM_WRITE, &cmos_year);
+		rtc_command(MEM_WRITE, &cmos_check);
+	}
+	return ret;
 }
 
 /*
  * Set the RTC time only.  Note that
  * we do not touch the date.
  */
-static int set_rtc_time(void)
+static int k_set_rtc_time(void)
 {
 	struct rtc_tm new_rtctm, old_rtctm;
 	unsigned long nowtime = xtime.tv_sec;
@@ -117,6 +153,63 @@ static int set_rtc_time(void)
 	return rtc_command(RTC_SETTIME, &new_rtctm);
 }
 
+static int rtc_ioctl(struct inode *inode, struct file *file,
+		     unsigned int cmd, unsigned long arg)
+{
+	unsigned int year;
+	struct rtc_time rtctm;
+	struct rtc_tm rtc_raw;
+
+	switch (cmd) {
+	case RTC_ALM_READ:
+	case RTC_ALM_SET:
+		break;
+
+	case RTC_RD_TIME:
+		get_rtc_time(&rtc_raw, &year);
+		rtctm.tm_sec  = rtc_raw.secs;
+		rtctm.tm_min  = rtc_raw.mins;
+		rtctm.tm_hour = rtc_raw.hours;
+		rtctm.tm_mday = rtc_raw.mday;
+		rtctm.tm_mon  = rtc_raw.mon - 1; /* month starts at 0 */
+		rtctm.tm_year = year - 1900; /* starts at 1900 */
+		return copy_to_user((void *)arg, &rtctm, sizeof(rtctm))
+				 ? -EFAULT : 0;
+
+	case RTC_SET_TIME:
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+
+		if (copy_from_user(&rtctm, (void *)arg, sizeof(rtctm)))
+			return -EFAULT;
+		rtc_raw.secs     = rtctm.tm_sec;
+		rtc_raw.mins     = rtctm.tm_min;
+		rtc_raw.hours    = rtctm.tm_hour;
+		rtc_raw.mday     = rtctm.tm_mday;
+		rtc_raw.mon      = rtctm.tm_mon + 1;
+		rtc_raw.year_off = 2;
+		year             = rtctm.tm_year + 1900;
+		return set_rtc_time(&rtc_raw, year);
+		break;
+
+	case RTC_EPOCH_READ:
+		return put_user(rtc_epoch, (unsigned long *)arg);
+
+	}
+	return -EINVAL;
+}
+
+static struct file_operations rtc_fops = {
+	ioctl:	rtc_ioctl,
+};
+
+static struct miscdevice rtc_dev = {
+	minor:	RTC_MINOR,
+	name:	"rtc",
+	fops:	&rtc_fops,
+};
+
+/* IOC / IOMD i2c driver */
 
 #define FORCE_ONES	0xdc
 #define SCL		0x02
@@ -184,9 +277,16 @@ static int ioc_client_reg(struct i2c_client *client)
 {
 	if (client->id == I2C_DRIVERID_PCF8583 &&
 	    client->addr == 0x50) {
+		struct rtc_tm rtctm;
+		unsigned int year;
+
 		rtc_client = client;
-		get_rtc_time();
-		set_rtc = set_rtc_time;
+		get_rtc_time(&rtctm, &year);
+
+		xtime.tv_usec = rtctm.cs * 10000;
+		xtime.tv_sec  = mktime(year, rtctm.mon, rtctm.mday,
+				       rtctm.hours, rtctm.mins, rtctm.secs);
+		set_rtc = k_set_rtc_time;
 	}
 
 	return 0;
@@ -212,9 +312,16 @@ static struct i2c_adapter ioc_ops = {
 
 static int __init i2c_ioc_init(void)
 {
+	int ret;
+
 	force_ones = FORCE_ONES | SCL | SDA;
 
-	return i2c_bit_add_bus(&ioc_ops);
+	ret = i2c_bit_add_bus(&ioc_ops);
+
+	if (ret >= 0)
+		misc_register(&rtc_dev);
+
+	return ret;
 }
 
 __initcall(i2c_ioc_init);