1 files changed, 112 insertions, 3 deletions

diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
index 9f3b6f4b45..f1e66870d7 100644
--- a/hw/ssi/aspeed_smc.c
+++ b/hw/ssi/aspeed_smc.c
@@ -145,6 +145,9 @@
 /* Flash opcodes. */
 #define SPI_OP_READ       0x03    /* Read data bytes (low frequency) */
 
+#define SNOOP_OFF         0xFF
+#define SNOOP_START       0x0
+
 /*
  * Default segments mapping addresses and size for each slave per
  * controller. These can be changed when board is initialized with the
@@ -566,6 +569,101 @@ static uint64_t aspeed_smc_flash_read(void *opaque, hwaddr addr, unsigned size)
     return ret;
 }
 
+/*
+ * TODO (clg@kaod.org): stolen from xilinx_spips.c. Should move to a
+ * common include header.
+ */
+typedef enum {
+    READ = 0x3,         READ_4 = 0x13,
+    FAST_READ = 0xb,    FAST_READ_4 = 0x0c,
+    DOR = 0x3b,         DOR_4 = 0x3c,
+    QOR = 0x6b,         QOR_4 = 0x6c,
+    DIOR = 0xbb,        DIOR_4 = 0xbc,
+    QIOR = 0xeb,        QIOR_4 = 0xec,
+
+    PP = 0x2,           PP_4 = 0x12,
+    DPP = 0xa2,
+    QPP = 0x32,         QPP_4 = 0x34,
+} FlashCMD;
+
+static int aspeed_smc_num_dummies(uint8_t command)
+{
+    switch (command) { /* check for dummies */
+    case READ: /* no dummy bytes/cycles */
+    case PP:
+    case DPP:
+    case QPP:
+    case READ_4:
+    case PP_4:
+    case QPP_4:
+        return 0;
+    case FAST_READ:
+    case DOR:
+    case QOR:
+    case DOR_4:
+    case QOR_4:
+        return 1;
+    case DIOR:
+    case FAST_READ_4:
+    case DIOR_4:
+        return 2;
+    case QIOR:
+    case QIOR_4:
+        return 4;
+    default:
+        return -1;
+    }
+}
+
+static bool aspeed_smc_do_snoop(AspeedSMCFlash *fl,  uint64_t data,
+                                unsigned size)
+{
+    AspeedSMCState *s = fl->controller;
+    uint8_t addr_width = aspeed_smc_flash_is_4byte(fl) ? 4 : 3;
+
+    if (s->snoop_index == SNOOP_OFF) {
+        return false; /* Do nothing */
+
+    } else if (s->snoop_index == SNOOP_START) {
+        uint8_t cmd = data & 0xff;
+        int ndummies = aspeed_smc_num_dummies(cmd);
+
+        /*
+         * No dummy cycles are expected with the current command. Turn
+         * off snooping and let the transfer proceed normally.
+         */
+        if (ndummies <= 0) {
+            s->snoop_index = SNOOP_OFF;
+            return false;
+        }
+
+        s->snoop_dummies = ndummies * 8;
+
+    } else if (s->snoop_index >= addr_width + 1) {
+
+        /* The SPI transfer has reached the dummy cycles sequence */
+        for (; s->snoop_dummies; s->snoop_dummies--) {
+            ssi_transfer(s->spi, s->regs[R_DUMMY_DATA] & 0xff);
+        }
+
+        /* If no more dummy cycles are expected, turn off snooping */
+        if (!s->snoop_dummies) {
+            s->snoop_index = SNOOP_OFF;
+        } else {
+            s->snoop_index += size;
+        }
+
+        /*
+         * Dummy cycles have been faked already. Ignore the current
+         * SPI transfer
+         */
+        return true;
+    }
+
+    s->snoop_index += size;
+    return false;
+}
+
 static void aspeed_smc_flash_write(void *opaque, hwaddr addr, uint64_t data,
                                    unsigned size)
 {
@@ -581,6 +679,10 @@ static void aspeed_smc_flash_write(void *opaque, hwaddr addr, uint64_t data,
 
     switch (aspeed_smc_flash_mode(fl)) {
     case CTRL_USERMODE:
+        if (aspeed_smc_do_snoop(fl, data, size)) {
+            break;
+        }
+
         for (i = 0; i < size; i++) {
             ssi_transfer(s->spi, (data >> (8 * i)) & 0xff);
         }
@@ -613,7 +715,9 @@ static const MemoryRegionOps aspeed_smc_flash_ops = {
 
 static void aspeed_smc_flash_update_cs(AspeedSMCFlash *fl)
 {
-    const AspeedSMCState *s = fl->controller;
+    AspeedSMCState *s = fl->controller;
+
+    s->snoop_index = aspeed_smc_is_ce_stop_active(fl) ? SNOOP_OFF : SNOOP_START;
 
     qemu_set_irq(s->cs_lines[fl->id], aspeed_smc_is_ce_stop_active(fl));
 }
@@ -652,6 +756,9 @@ static void aspeed_smc_reset(DeviceState *d)
     if (s->ctrl->segments == aspeed_segments_fmc) {
         s->regs[s->r_conf] |= (CONF_FLASH_TYPE_SPI << CONF_FLASH_TYPE0);
     }
+
+    s->snoop_index = SNOOP_OFF;
+    s->snoop_dummies = 0;
 }
 
 static uint64_t aspeed_smc_read(void *opaque, hwaddr addr, unsigned int size)
@@ -793,10 +900,12 @@ static void aspeed_smc_realize(DeviceState *dev, Error **errp)
 
 static const VMStateDescription vmstate_aspeed_smc = {
     .name = "aspeed.smc",
-    .version_id = 1,
-    .minimum_version_id = 1,
+    .version_id = 2,
+    .minimum_version_id = 2,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32_ARRAY(regs, AspeedSMCState, ASPEED_SMC_R_MAX),
+        VMSTATE_UINT8(snoop_index, AspeedSMCState),
+        VMSTATE_UINT8(snoop_dummies, AspeedSMCState),
         VMSTATE_END_OF_LIST()
     }
 };