[MIPS] lib_mips/time.c: Fix CP0 count register usage and timer routines

MIPS port has two problems in timer routines. One is now we assume CFG_HZ
equals to CP0 counter frequency, but this is wrong. CFG_HZ has to be 1000
in the U-Boot system.

The other is we don't have a proper time management counter like timestamp
other ARCHs have. We need the 32-bit millisecond clock counter.

This patch introduces timestamp and CYCLES_PER_JIFFY. timestamp is a
32-bit non-overflowing CFG_HZ counter, and CYCLES_PER_JIFFY is the number
of calculated CP0 counter cycles in a CFG_HZ.

STRATEGY:

* Fix improper CFG_HZ value to have 1000

* Use CFG_MIPS_TIMER_FREQ for timer counter frequency, instead.

* timer_init: initialize timestamp and set up the first timer expiration.
  Note that we don't need to initialize CP0 count/compare registers here
  as they have been already zeroed out on the system reset. Leave them as
  they are.

* get_timer: calculate how many timestamps have been passed, then return
  base-relative timestamp. Make sure we can easily count missed timestamps
  regardless of CP0 count/compare value.

* get_ticks: return the current timestamp, that is get_timer(0).

Most parts are from good old Linux v2.6.16 kernel.

v2:
- Remove FIXME comments as they turned out to be trivial.
- Use CP0 compare register as a global variable for expirelo.
- Kill a global variable 'cycles_per_jiffy'. Use #define CYCLES_PER_JIFFY
  instead.

Signed-off-by: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp>

diff --git a/include/configs/dbau1x00.h b/include/configs/dbau1x00.h
index b2f606f498b794042ce474afd282ac373b9448d6..45ff1e73055eec73b7065f4d3c363926a0ec11c7 100644 (file)
--- a/include/configs/dbau1x00.h
+++ b/include/configs/dbau1x00.h
@@ -148,7 +148,9 @@
 #error "Invalid CPU frequency - must be multiple of 12!"
 #endif
 
-#define CFG_HZ                  (CFG_MHZ * 1000000) /* FIXME causes overflow in net.c */
+#define CFG_MIPS_TIMER_FREQ    (CFG_MHZ * 1000000)
+
+#define CFG_HZ                 1000
 
 #define CFG_SDRAM_BASE         0x80000000     /* Cached addr */
 

diff --git a/include/configs/gth2.h b/include/configs/gth2.h
index c2a50c1f473816307f6d660bdaf7ac12ae664fb8..23618db667d1a788b696a4b7846cae06ba0c6a09 100644 (file)
--- a/include/configs/gth2.h
+++ b/include/configs/gth2.h
@@ -118,7 +118,9 @@
 
 #define CFG_MHZ                        500
 
-#define CFG_HZ                 (CFG_MHZ * 1000000) /* FIXME causes overflow in net.c */
+#define CFG_MIPS_TIMER_FREQ    (CFG_MHZ * 1000000)
+
+#define CFG_HZ                 1000
 
 #define CFG_SDRAM_BASE         0x80000000     /* Cached addr */
 

diff --git a/include/configs/incaip.h b/include/configs/incaip.h
index 5ca00b373407d93c81dbd7e07e70e57490d84640..2e4ee66cf6167e803970a508ea83ec7bb234c6f4 100644 (file)
--- a/include/configs/incaip.h
+++ b/include/configs/incaip.h
@@ -118,7 +118,9 @@
 
 #define CFG_BOOTPARAMS_LEN     128*1024
 
-#define CFG_HZ                 (incaip_get_cpuclk() / 2)
+#define CFG_MIPS_TIMER_FREQ    (incaip_get_cpuclk() / 2)
+
+#define CFG_HZ                 1000
 
 #define CFG_SDRAM_BASE         0x80000000
 

diff --git a/include/configs/pb1x00.h b/include/configs/pb1x00.h
index 810e0f0462875938afb0585b5efcc7f07dba8892..181cd11b86eddc23530d9ef4ad78a3e824451f5f 100644 (file)
--- a/include/configs/pb1x00.h
+++ b/include/configs/pb1x00.h
@@ -81,7 +81,9 @@
 
 #define CFG_BOOTPARAMS_LEN     128*1024
 
-#define CFG_HZ                 396000000      /* FIXME causes overflow in net.c */
+#define CFG_MIPS_TIMER_FREQ    396000000
+
+#define CFG_HZ                 1000
 
 #define CFG_SDRAM_BASE         0x80000000     /* Cached addr */
 

diff --git a/include/configs/purple.h b/include/configs/purple.h
index 1be4e055f99bc1e413bceba34a4f1888aa566ec1..ef92637127ff050c8cd79ab976b2a919430c04f4 100644 (file)
--- a/include/configs/purple.h
+++ b/include/configs/purple.h
@@ -114,7 +114,8 @@
 #define        CFG_PROMPT              "PURPLE # "     /* Monitor Command Prompt    */
 #define        CFG_CBSIZE              256             /* Console I/O Buffer Size   */
 #define        CFG_PBSIZE (CFG_CBSIZE+sizeof(CFG_PROMPT)+16)  /* Print Buffer Size */
-#define CFG_HZ                 (CPU_CLOCK_RATE/2)
+#define CFG_MIPS_TIMER_FREQ    (CPU_CLOCK_RATE/2)
+#define CFG_HZ                 1000
 #define        CFG_MAXARGS             16              /* max number of command args*/
 
 #define        CFG_LOAD_ADDR           0x80500000      /* default load address */

diff --git a/include/configs/qemu-mips.h b/include/configs/qemu-mips.h
index d6bcc8e3b16c8df201796470a33eb7a2919747c1..3dfd2181f4844fef4436442f5ef481359ecb4f5e 100644 (file)
--- a/include/configs/qemu-mips.h
+++ b/include/configs/qemu-mips.h
@@ -120,7 +120,9 @@
 
 #define CFG_MHZ                        132
 
-#define CFG_HZ                 (CFG_MHZ * 1000000)
+#define CFG_MIPS_TIMER_FREQ    (CFG_MHZ * 1000000)
+
+#define CFG_HZ                 1000
 
 #define CFG_SDRAM_BASE         0x80000000      /* Cached addr */
 

diff --git a/include/configs/tb0229.h b/include/configs/tb0229.h
index dadf5d3329f327c7799b2eb7183659925702c40f..fc2357d4064dd719863692df79dcf3ad5e11529e 100644 (file)
--- a/include/configs/tb0229.h
+++ b/include/configs/tb0229.h
@@ -122,7 +122,9 @@
 
 #define CFG_BOOTPARAMS_LEN     128*1024
 
-#define CFG_HZ                 (CPU_TCLOCK_RATE/4)
+#define CFG_MIPS_TIMER_FREQ    (CPU_TCLOCK_RATE/4)
+
+#define CFG_HZ                 1000
 
 #define CFG_SDRAM_BASE         0x80000000
 

diff --git a/lib_mips/time.c b/lib_mips/time.c
index fe365303b4d7380f535aa44bac244debfe5a44b9..1e9278996e54d2f43589106e9a52c48f3349ef24 100644 (file)
--- a/lib_mips/time.c
+++ b/lib_mips/time.c
@@ -24,31 +24,50 @@
 #include <common.h>
 #include <asm/mipsregs.h>
 
+static unsigned long timestamp;
+
+/* how many counter cycles in a jiffy */
+#define CYCLES_PER_JIFFY       (CFG_MIPS_TIMER_FREQ + CFG_HZ / 2) / CFG_HZ
+
 /*
  * timer without interrupts
  */
 
 int timer_init(void)
 {
-       write_c0_compare(0);
-       write_c0_count(0);
+       /* Set up the timer for the first expiration. */
+       timestamp = 0;
+       write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
 
        return 0;
 }
 
 void reset_timer(void)
 {
-       write_c0_count(0);
+       timestamp = 0;
+       write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
 }
 
 ulong get_timer(ulong base)
 {
-       return read_c0_count() - base;
+       unsigned int count;
+       unsigned int expirelo = read_c0_compare();
+
+       /* Check to see if we have missed any timestamps. */
+       count = read_c0_count();
+       while ((count - expirelo) < 0x7fffffff) {
+               expirelo += CYCLES_PER_JIFFY;
+               timestamp++;
+       }
+       write_c0_compare(expirelo);
+
+       return (timestamp - base);
 }
 
 void set_timer(ulong t)
 {
-       write_c0_count(t);
+       timestamp = t;
+       write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
 }
 
 void udelay(unsigned long usec)
@@ -66,7 +85,7 @@ void udelay(unsigned long usec)
  */
 unsigned long long get_ticks(void)
 {
-       return read_c0_count();
+       return get_timer(0);
 }
 
 /*