[Qemu-devel] [PATCH 08/11] aspeed/smc: add support for DMAs

[Cédric Le Goater]

The FMC controller on the Aspeed SoCs support DMA to access the flash
modules. It can operate in a normal mode, to copy to or from the flash
module mapping window, or in a checksum calculation mode, to evaluate
the best clock settings for reads.

Our primary need is to support the checksum calculation mode and the
model only implements synchronous DMA accesses. Something to improve
in the future.

Signed-off-by: Cédric Le Goater <address@hidden>
---
 hw/ssi/aspeed_smc.c | 159 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 152 insertions(+), 7 deletions(-)

diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
index 500de6d16d09..534faec4c111 100644
--- a/hw/ssi/aspeed_smc.c
+++ b/hw/ssi/aspeed_smc.c
@@ -72,6 +72,10 @@
 #define   CTRL_CMD_MASK            0xff
 #define   CTRL_DUMMY_HIGH_SHIFT    14
 #define   CTRL_AST2400_SPI_4BYTE   (1 << 13)
+#define CE_CTRL_CLOCK_FREQ_SHIFT   8
+#define CE_CTRL_CLOCK_FREQ_MASK    0xf
+#define CE_CTRL_CLOCK_FREQ(div)                                         \
+    (((div) & CE_CTRL_CLOCK_FREQ_MASK) << CE_CTRL_CLOCK_FREQ_SHIFT)
 #define   CTRL_DUMMY_LOW_SHIFT     6 /* 2 bits [7:6] */
 #define   CTRL_CE_STOP_ACTIVE      (1 << 2)
 #define   CTRL_CMD_MODE_MASK       0x3
@@ -107,10 +111,10 @@
 #define   DMA_CTRL_DELAY_SHIFT  8
 #define   DMA_CTRL_FREQ_MASK    0xf
 #define   DMA_CTRL_FREQ_SHIFT   4
-#define   DMA_CTRL_MODE         (1 << 3)
+#define   DMA_CTRL_CALIB        (1 << 3)
 #define   DMA_CTRL_CKSUM        (1 << 2)
-#define   DMA_CTRL_DIR          (1 << 1)
-#define   DMA_CTRL_EN           (1 << 0)
+#define   DMA_CTRL_WRITE        (1 << 1)
+#define   DMA_CTRL_ENABLE       (1 << 0)
 
 /* DMA Flash Side Address */
 #define R_DMA_FLASH_ADDR  (0x84 / 4)
@@ -142,6 +146,21 @@
 #define ASPEED_SOC_SPI_FLASH_BASE   0x30000000
 #define ASPEED_SOC_SPI2_FLASH_BASE  0x38000000
 
+/*
+ * DMA DRAM addresses should be 4 bytes aligned and the valid address
+ * range is the full address space of the SoC
+ *
+ * DMA flash addresses should be 4 bytes aligned and the valid address
+ * range is 0x20000000 - 0x2FFFFFFF.
+ *
+ * DMA length is from 4 bytes to 32MB
+ *   0: 4 bytes
+ *   0x7FFFFF: 32M bytes
+ */
+#define DMA_DRAM_MASK(s)        ((s)->max_ram_size - 4)
+#define DMA_FLASH_MASK          0x0FFFFFFC
+#define DMA_LENGTH_MASK         0x01FFFFFC
+
 /* Flash opcodes. */
 #define SPI_OP_READ       0x03    /* Read data bytes (low frequency) */
 
@@ -625,9 +644,6 @@ static void aspeed_smc_reset(DeviceState *d)
 
     memset(s->regs, 0, sizeof s->regs);
 
-    /* Pretend DMA is done (u-boot initialization) */
-    s->regs[R_INTR_CTRL] = INTR_CTRL_DMA_STATUS;
-
     /* Unselect all slaves */
     for (i = 0; i < s->num_cs; ++i) {
         s->regs[s->r_ctrl0 + i] |= CTRL_CE_STOP_ACTIVE;
@@ -664,6 +680,11 @@ static uint64_t aspeed_smc_read(void *opaque, hwaddr addr, 
unsigned int size)
         addr == s->r_timings ||
         addr == s->r_ce_ctrl ||
         addr == R_INTR_CTRL ||
+        (s->ctrl->has_dma && addr == R_DMA_CTRL) ||
+        (s->ctrl->has_dma && addr == R_DMA_FLASH_ADDR) ||
+        (s->ctrl->has_dma && addr == R_DMA_DRAM_ADDR) ||
+        (s->ctrl->has_dma && addr == R_DMA_LEN) ||
+        (s->ctrl->has_dma && addr == R_DMA_CHECKSUM) ||
         (addr >= R_SEG_ADDR0 && addr < R_SEG_ADDR0 + s->ctrl->max_slaves) ||
         (addr >= s->r_ctrl0 && addr < s->r_ctrl0 + s->ctrl->max_slaves)) {
         return s->regs[addr];
@@ -674,6 +695,115 @@ static uint64_t aspeed_smc_read(void *opaque, hwaddr 
addr, unsigned int size)
     }
 }
 
+/*
+ * Accumulate the result of the reads to provide a checksum that will
+ * be used to validate the read timing settings.
+ */
+static void aspeed_smc_dma_checksum(AspeedSMCState *s)
+{
+    uint32_t data;
+
+    if (s->regs[R_DMA_CTRL] & DMA_CTRL_WRITE) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: invalid direction for DMA checksum\n",  __func__);
+        return;
+    }
+
+    while (s->regs[R_DMA_LEN]) {
+        cpu_physical_memory_read(s->regs[R_DMA_FLASH_ADDR], &data, 4);
+
+        /*
+         * When the DMA is on-going, the DMA registers are updated
+         * with the current working addresses and length.
+         */
+        s->regs[R_DMA_CHECKSUM] += data;
+        s->regs[R_DMA_FLASH_ADDR] += 4;
+        s->regs[R_DMA_LEN] -= 4;
+    }
+}
+
+static void aspeed_smc_dma_rw(AspeedSMCState *s)
+{
+    uint32_t data;
+
+    while (s->regs[R_DMA_LEN]) {
+        if (s->regs[R_DMA_CTRL] & DMA_CTRL_WRITE) {
+            cpu_physical_memory_read(s->regs[R_DMA_DRAM_ADDR], &data, 4);
+            cpu_physical_memory_write(s->regs[R_DMA_FLASH_ADDR], &data, 4);
+        } else {
+            cpu_physical_memory_read(s->regs[R_DMA_FLASH_ADDR], &data, 4);
+            cpu_physical_memory_write(s->regs[R_DMA_DRAM_ADDR], &data, 4);
+        }
+
+        /*
+         * When the DMA is on-going, the DMA registers are updated
+         * with the current working addresses and length.
+         */
+        s->regs[R_DMA_FLASH_ADDR] += 4;
+        s->regs[R_DMA_DRAM_ADDR] += 4;
+        s->regs[R_DMA_LEN] -= 4;
+    }
+}
+
+static void aspeed_smc_dma_stop(AspeedSMCState *s)
+{
+    /*
+     * When the DMA is disabled, INTR_CTRL_DMA_STATUS=0 means the
+     * engine is idle
+     */
+    s->regs[R_INTR_CTRL] &= ~INTR_CTRL_DMA_STATUS;
+    s->regs[R_DMA_CHECKSUM] = 0;
+
+    /*
+     * Lower the DMA irq in any case. The IRQ control register could
+     * have been cleared before disabling the DMA.
+     */
+    qemu_irq_lower(s->irq);
+}
+
+/*
+ * When INTR_CTRL_DMA_STATUS=1, the DMA has completed and a new DMA
+ * can start even if the result of the previous was not collected.
+ */
+static bool aspeed_smc_dma_in_progress(AspeedSMCState *s)
+{
+    return s->regs[R_DMA_CTRL] & DMA_CTRL_ENABLE &&
+        !(s->regs[R_INTR_CTRL] & INTR_CTRL_DMA_STATUS);
+}
+
+static void aspeed_smc_dma_done(AspeedSMCState *s)
+{
+    s->regs[R_INTR_CTRL] |= INTR_CTRL_DMA_STATUS;
+    if (s->regs[R_INTR_CTRL] & INTR_CTRL_DMA_EN) {
+        qemu_irq_raise(s->irq);
+    }
+}
+
+static void aspeed_smc_dma_ctrl(AspeedSMCState *s, uint64_t dma_ctrl)
+{
+    if (!(dma_ctrl & DMA_CTRL_ENABLE)) {
+        s->regs[R_DMA_CTRL] = dma_ctrl;
+
+        aspeed_smc_dma_stop(s);
+        return;
+    }
+
+    if (aspeed_smc_dma_in_progress(s)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA in progress\n",  __func__);
+        return;
+    }
+
+    s->regs[R_DMA_CTRL] = dma_ctrl;
+
+    if (s->regs[R_DMA_CTRL] & DMA_CTRL_CKSUM) {
+        aspeed_smc_dma_checksum(s);
+    } else {
+        aspeed_smc_dma_rw(s);
+    }
+
+    aspeed_smc_dma_done(s);
+}
+
 static void aspeed_smc_write(void *opaque, hwaddr addr, uint64_t data,
                              unsigned int size)
 {
@@ -697,6 +827,19 @@ static void aspeed_smc_write(void *opaque, hwaddr addr, 
uint64_t data,
         if (value != s->regs[R_SEG_ADDR0 + cs]) {
             aspeed_smc_flash_set_segment(s, cs, value);
         }
+    } else if (addr == R_INTR_CTRL) {
+        s->regs[addr] = value;
+    } else if (s->ctrl->has_dma && addr == R_DMA_CTRL) {
+        aspeed_smc_dma_ctrl(s, value);
+    } else if (s->ctrl->has_dma && addr == R_DMA_DRAM_ADDR) {
+        value &= DMA_DRAM_MASK(s);
+        s->regs[addr] = s->sdram_base | value;
+    } else if (s->ctrl->has_dma && addr == R_DMA_FLASH_ADDR) {
+        value &= DMA_FLASH_MASK;
+        s->regs[addr] = ASPEED_SOC_FMC_FLASH_BASE | value;
+    } else if (s->ctrl->has_dma && addr == R_DMA_LEN) {
+        value &= DMA_LENGTH_MASK;
+        s->regs[addr] = value;
     } else {
         qemu_log_mask(LOG_UNIMP, "%s: not implemented: 0x%" HWADDR_PRIx "\n",
                       __func__, addr);
@@ -729,6 +872,9 @@ static void aspeed_smc_realize(DeviceState *dev, Error 
**errp)
     s->r_timings = s->ctrl->r_timings;
     s->conf_enable_w0 = s->ctrl->conf_enable_w0;
 
+    /* DMA irq */
+    sysbus_init_irq(sbd, &s->irq);
+
     /* Enforce some real HW limits */
     if (s->num_cs > s->ctrl->max_slaves) {
         qemu_log_mask(LOG_GUEST_ERROR, "%s: num_cs cannot exceed: %d\n",
@@ -739,7 +885,6 @@ static void aspeed_smc_realize(DeviceState *dev, Error 
**errp)
     s->spi = ssi_create_bus(dev, "spi");
 
     /* Setup cs_lines for slaves */
-    sysbus_init_irq(sbd, &s->irq);
     s->cs_lines = g_new0(qemu_irq, s->num_cs);
     ssi_auto_connect_slaves(dev, s->cs_lines, s->spi);
 
-- 
2.17.1