[PATCH] char/rtc: Handle memory-mapped chips properly

Handle memory-mapped chips properly, needed for example on DECstations.
This support was in Linux 2.4 but for some reason got lost in 2.6.  This
patch is taken directly from the linux-mips repository.

[akpm@osdl.org: cleanup]
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
Cc: Paul Gortmaker <penguin@muskoka.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 41 insertions, 9 deletions

diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
index cc7bd1a3095b..6ccc364c08df 100644
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -46,13 +46,12 @@
  *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
  *      1.12    Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
  *              CONFIG_HPET_EMULATE_RTC
+ *      1.12a   Maciej W. Rozycki: Handle memory-mapped chips properly.
  *      1.12ac  Alan Cox: Allow read access to the day of week register
  */
 
 #define RTC_VERSION             "1.12ac"
 
-#define RTC_IO_EXTENT   0x8
-
 /*
  *      Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
  *      interrupts disabled. Due to the index-port/data-port (0x70/0x71)
@@ -337,7 +336,15 @@ static ssize_t rtc_read(struct file *file, char __user *buf,
         if (rtc_has_irq == 0)
                 return -EIO;
 
-        if (count < sizeof(unsigned))
+        /*
+         * Historically this function used to assume that sizeof(unsigned long)
+         * is the same in userspace and kernelspace.  This lead to problems
+         * for configurations with multiple ABIs such a the MIPS o32 and 64
+         * ABIs supported on the same kernel.  So now we support read of both
+         * 4 and 8 bytes and assume that's the sizeof(unsigned long) in the
+         * userspace ABI.
+         */
+        if (count != sizeof(unsigned int) && count !=  sizeof(unsigned long))
                 return -EINVAL;
 
         add_wait_queue(&rtc_wait, &wait);
@@ -368,10 +375,12 @@ static ssize_t rtc_read(struct file *file, char __user *buf,
                 schedule();
         } while (1);
 
-        if (count < sizeof(unsigned long))
-                retval = put_user(data, (unsigned int __user *)buf) ?: sizeof(int); 
+        if (count == sizeof(unsigned int))
+                retval = put_user(data, (unsigned int __user *)buf) ?: sizeof(int);
         else
                 retval = put_user(data, (unsigned long __user *)buf) ?: sizeof(long);
+        if (!retval)
+                retval = count;
  out:
         current->state = TASK_RUNNING;
         remove_wait_queue(&rtc_wait, &wait);
@@ -923,6 +932,9 @@ static int __init rtc_init(void)
         struct sparc_isa_device *isa_dev;
 #endif
 #endif
+#ifndef __sparc__
+        void *r;
+#endif
 
 #ifdef __sparc__
         for_each_ebus(ebus) {
@@ -964,8 +976,13 @@ found:
         }
 no_irq:
 #else
-        if (!request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc")) {
-                printk(KERN_ERR "rtc: I/O port %d is not free.\n", RTC_PORT (0));
+        if (RTC_IOMAPPED)
+                r = request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
+        else
+                r = request_mem_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
+        if (!r) {
+                printk(KERN_ERR "rtc: I/O resource %lx is not free.\n",
+                       (long)(RTC_PORT(0)));
                 return -EIO;
         }
 
@@ -979,7 +996,10 @@ no_irq:
         if(request_irq(RTC_IRQ, rtc_int_handler_ptr, IRQF_DISABLED, "rtc", NULL)) {
                 /* Yeah right, seeing as irq 8 doesn't even hit the bus. */
                 printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
-                release_region(RTC_PORT(0), RTC_IO_EXTENT);
+                if (RTC_IOMAPPED)
+                        release_region(RTC_PORT(0), RTC_IO_EXTENT);
+                else
+                        release_mem_region(RTC_PORT(0), RTC_IO_EXTENT);
                 return -EIO;
         }
         hpet_rtc_timer_init();
@@ -1079,7 +1099,10 @@ static void __exit rtc_exit (void)
         if (rtc_has_irq)
                 free_irq (rtc_irq, &rtc_port);
 #else
-        release_region (RTC_PORT (0), RTC_IO_EXTENT);
+        if (RTC_IOMAPPED)
+                release_region(RTC_PORT(0), RTC_IO_EXTENT);
+        else
+                release_mem_region(RTC_PORT(0), RTC_IO_EXTENT);
 #ifdef RTC_IRQ
         if (rtc_has_irq)
                 free_irq (RTC_IRQ, NULL);
diff --git a/include/asm-mips/mach-dec/mc146818rtc.h b/include/asm-mips/mach-dec/mc146818rtc.h
index 6d37a5675803..6724e99e43e1 100644
--- a/include/asm-mips/mach-dec/mc146818rtc.h
+++ b/include/asm-mips/mach-dec/mc146818rtc.h
@@ -19,6 +19,8 @@
 
 extern volatile u8 *dec_rtc_base;
 
+#define ARCH_RTC_LOCATION
+
 #define RTC_PORT(x)     CPHYSADDR((long)dec_rtc_base)
 #define RTC_IO_EXTENT   dec_kn_slot_size
 #define RTC_IOMAPPED    0
diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h
index bbc93ae217e1..432b2fa24929 100644
--- a/include/linux/mc146818rtc.h
+++ b/include/linux/mc146818rtc.h
@@ -89,4 +89,11 @@ extern spinlock_t rtc_lock;		/* serialize CMOS RAM access */
 # define RTC_VRT 0x80           /* valid RAM and time */
 /**********************************************************************/
 
+#ifndef ARCH_RTC_LOCATION       /* Override by <asm/mc146818rtc.h>? */
+
+#define RTC_IO_EXTENT   0x8
+#define RTC_IOMAPPED    1       /* Default to I/O mapping. */
+
+#endif /* ARCH_RTC_LOCATION */
+
 #endif /* _MC146818RTC_H */