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Re: [Qemu-devel] [PATCH v2 4/4] ARM: exynos4210_pmu: Add software reset


From: Maksim Kozlov
Subject: Re: [Qemu-devel] [PATCH v2 4/4] ARM: exynos4210_pmu: Add software reset support
Date: Mon, 23 Jul 2012 15:01:42 +0400
User-agent: Mozilla/5.0 (X11; Linux i686; rv:10.0) Gecko/20120129 Thunderbird/10.0

20.07.2012 18:32, Peter Maydell пишет:
On 12 July 2012 17:54, Maksim Kozlov<address@hidden>  wrote:
Signed-off-by: Maksim Kozlov<address@hidden>
---
  hw/exynos4210_pmu.c |   40 +++++++++++++++++++++++++++++++++-------
  1 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/hw/exynos4210_pmu.c b/hw/exynos4210_pmu.c
index 7f09c79..96588d9 100644
--- a/hw/exynos4210_pmu.c
+++ b/hw/exynos4210_pmu.c
@@ -18,13 +18,8 @@
   *  with this program; if not, see<http://www.gnu.org/licenses/>.
   */

-/*
- * This model implements PMU registers just as a bulk of memory. Currently,
- * the only reason this device exists is that secondary CPU boot loader
- * uses PMU INFORM5 register as a holding pen.
- */
-
  #include "sysbus.h"
+#include "sysemu.h"

  #ifndef DEBUG_PMU
  #define DEBUG_PMU           0
@@ -230,6 +225,8 @@

  #define EXYNOS4210_PMU_REGS_MEM_SIZE 0x3d0c

+#define SWRESET_SYSTEM_MASK     0x00000001
+
  typedef struct Exynos4210PmuReg {
      const char  *name; /* for debug only */
      uint32_t     offset;
@@ -458,7 +455,17 @@ static void exynos4210_pmu_write(void *opaque, 
target_phys_addr_t offset,
      PRINT_DEBUG_EXTEND("%s [0x%04x]<- 0x%04x\n",
               exynos4210_pmu_regs[index].name, (uint32_t)offset, 
(uint32_t)val);

-    s->reg[index] = val;
+    switch (offset) {
+    case SWRESET:
+        if (val&  SWRESET_SYSTEM_MASK) {
+            s->reg[index] = val;
+            qemu_system_reset_request();
+        }
+        break;
+    default:
+        s->reg[index] = val;
+        break;
+    }
  }

  static const MemoryRegionOps exynos4210_pmu_ops = {
@@ -477,9 +484,28 @@ static void exynos4210_pmu_reset(DeviceState *dev)
      Exynos4210PmuState *s =
              container_of(dev, Exynos4210PmuState, busdev.qdev);
      unsigned i;
+    uint32_t index = exynos4210_pmu_get_register_index(s, SWRESET);
+    uint32_t swreset = s->reg[index];

      /* Set default values for registers */
      for (i = 0; i<  PMU_NUM_OF_REGISTERS; i++) {
+        if (swreset) {
+            switch (exynos4210_pmu_regs[i].offset) {
+            case INFORM0:
+            case INFORM1:
+            case INFORM2:
+            case INFORM3:
+            case INFORM4:
+            case INFORM5:
+            case INFORM6:
+            case INFORM7:
+            case PS_HOLD_CONTROL:
+                /* keep these registers during SW reset */
+                continue;
+            default:
+                break;
+            }
+        }
          s->reg[i] = exynos4210_pmu_regs[i].reset_value;
      }
  }
This patch seems to be trying to make a distinction that QEMU doesn't
support, ie between system wide "software reset" and system wide
"hard reset". I'm not convinced about the wisdom of trying to paper
over this lack with a single-device workaround.
Peter, if we add callback (*swreset)() into DeviceClass, whether it will be an acceptable solution? And devices which have different behavior during swreset can register different function for that. What do you think about this?

-- PMM



--
Best regards,
Maksim Kozlov
Leading Engineer
Advanced Software Group,
Samsung Moscow Research Center
e-mail: address@hidden
Tel: 7(495) 797-25-00 ext. 3949





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