summary refs log tree commit diff stats
path: root/hw/ssi/aspeed_smc.c
diff options
context:
space:
mode:
Diffstat (limited to 'hw/ssi/aspeed_smc.c')
-rw-r--r--hw/ssi/aspeed_smc.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
index 7a0cd7607f..5c3436db5e 100644
--- a/hw/ssi/aspeed_smc.c
+++ b/hw/ssi/aspeed_smc.c
@@ -870,6 +870,36 @@ static void aspeed_smc_dma_calibration(AspeedSMCState *s)
 }
 
 /*
+ * Emulate read errors in the DMA Checksum Register for high
+ * frequencies and optimistic settings of the Read Timing Compensation
+ * Register. This will help in tuning the SPI timing calibration
+ * algorithm.
+ */
+static bool aspeed_smc_inject_read_failure(AspeedSMCState *s)
+{
+    uint8_t delay =
+        (s->regs[R_DMA_CTRL] >> DMA_CTRL_DELAY_SHIFT) & DMA_CTRL_DELAY_MASK;
+    uint8_t hclk_mask =
+        (s->regs[R_DMA_CTRL] >> DMA_CTRL_FREQ_SHIFT) & DMA_CTRL_FREQ_MASK;
+
+    /*
+     * Typical values of a palmetto-bmc machine.
+     */
+    switch (aspeed_smc_hclk_divisor(hclk_mask)) {
+    case 4 ... 16:
+        return false;
+    case 3: /* at least one HCLK cycle delay */
+        return (delay & 0x7) < 1;
+    case 2: /* at least two HCLK cycle delay */
+        return (delay & 0x7) < 2;
+    case 1: /* (> 100MHz) is above the max freq of the controller */
+        return true;
+    default:
+        g_assert_not_reached();
+    }
+}
+
+/*
  * Accumulate the result of the reads to provide a checksum that will
  * be used to validate the read timing settings.
  */
@@ -905,6 +935,11 @@ static void aspeed_smc_dma_checksum(AspeedSMCState *s)
         s->regs[R_DMA_FLASH_ADDR] += 4;
         s->regs[R_DMA_LEN] -= 4;
     }
+
+    if (s->inject_failure && aspeed_smc_inject_read_failure(s)) {
+        s->regs[R_DMA_CHECKSUM] = 0xbadc0de;
+    }
+
 }
 
 static void aspeed_smc_dma_rw(AspeedSMCState *s)
@@ -1185,6 +1220,7 @@ static const VMStateDescription vmstate_aspeed_smc = {
 
 static Property aspeed_smc_properties[] = {
     DEFINE_PROP_UINT32("num-cs", AspeedSMCState, num_cs, 1),
+    DEFINE_PROP_BOOL("inject-failure", AspeedSMCState, inject_failure, false),
     DEFINE_PROP_UINT64("sdram-base", AspeedSMCState, sdram_base, 0),
     DEFINE_PROP_LINK("dram", AspeedSMCState, dram_mr,
                      TYPE_MEMORY_REGION, MemoryRegion *),