hw/ssi: Add SiFive SPI controller support

This adds the SiFive SPI controller model for the FU540 SoC.
The direct memory-mapped SPI flash mode is unsupported.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210126060007.12904-4-bmeng.cn@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

3 files changed, 363 insertions, 0 deletions

diff --git a/hw/ssi/Kconfig b/hw/ssi/Kconfig
index 9e54a0c8dd..7d90a02181 100644
--- a/hw/ssi/Kconfig
+++ b/hw/ssi/Kconfig
@@ -2,6 +2,10 @@ config PL022
     bool
     select SSI
 
+config SIFIVE_SPI
+    bool
+    select SSI
+
 config SSI
     bool
 
diff --git a/hw/ssi/meson.build b/hw/ssi/meson.build
index dee00c0da6..3d6bc82ab1 100644
--- a/hw/ssi/meson.build
+++ b/hw/ssi/meson.build
@@ -2,6 +2,7 @@ softmmu_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files('aspeed_smc.c'))
 softmmu_ss.add(when: 'CONFIG_MSF2', if_true: files('mss-spi.c'))
 softmmu_ss.add(when: 'CONFIG_NPCM7XX', if_true: files('npcm7xx_fiu.c'))
 softmmu_ss.add(when: 'CONFIG_PL022', if_true: files('pl022.c'))
+softmmu_ss.add(when: 'CONFIG_SIFIVE_SPI', if_true: files('sifive_spi.c'))
 softmmu_ss.add(when: 'CONFIG_SSI', if_true: files('ssi.c'))
 softmmu_ss.add(when: 'CONFIG_STM32F2XX_SPI', if_true: files('stm32f2xx_spi.c'))
 softmmu_ss.add(when: 'CONFIG_XILINX_SPI', if_true: files('xilinx_spi.c'))
diff --git a/hw/ssi/sifive_spi.c b/hw/ssi/sifive_spi.c
new file mode 100644
index 0000000000..0c9ebca3c8
--- /dev/null
+++ b/hw/ssi/sifive_spi.c
@@ -0,0 +1,358 @@
+/*
+ * QEMU model of the SiFive SPI Controller
+ *
+ * Copyright (c) 2021 Wind River Systems, Inc.
+ *
+ * Author:
+ *   Bin Meng <bin.meng@windriver.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "hw/sysbus.h"
+#include "hw/ssi/ssi.h"
+#include "sysemu/sysemu.h"
+#include "qemu/fifo8.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "hw/ssi/sifive_spi.h"
+
+#define R_SCKDIV        (0x00 / 4)
+#define R_SCKMODE       (0x04 / 4)
+#define R_CSID          (0x10 / 4)
+#define R_CSDEF         (0x14 / 4)
+#define R_CSMODE        (0x18 / 4)
+#define R_DELAY0        (0x28 / 4)
+#define R_DELAY1        (0x2C / 4)
+#define R_FMT           (0x40 / 4)
+#define R_TXDATA        (0x48 / 4)
+#define R_RXDATA        (0x4C / 4)
+#define R_TXMARK        (0x50 / 4)
+#define R_RXMARK        (0x54 / 4)
+#define R_FCTRL         (0x60 / 4)
+#define R_FFMT          (0x64 / 4)
+#define R_IE            (0x70 / 4)
+#define R_IP            (0x74 / 4)
+
+#define FMT_DIR         (1 << 3)
+
+#define TXDATA_FULL     (1 << 31)
+#define RXDATA_EMPTY    (1 << 31)
+
+#define IE_TXWM         (1 << 0)
+#define IE_RXWM         (1 << 1)
+
+#define IP_TXWM         (1 << 0)
+#define IP_RXWM         (1 << 1)
+
+#define FIFO_CAPACITY   8
+
+static void sifive_spi_txfifo_reset(SiFiveSPIState *s)
+{
+    fifo8_reset(&s->tx_fifo);
+
+    s->regs[R_TXDATA] &= ~TXDATA_FULL;
+    s->regs[R_IP] &= ~IP_TXWM;
+}
+
+static void sifive_spi_rxfifo_reset(SiFiveSPIState *s)
+{
+    fifo8_reset(&s->rx_fifo);
+
+    s->regs[R_RXDATA] |= RXDATA_EMPTY;
+    s->regs[R_IP] &= ~IP_RXWM;
+}
+
+static void sifive_spi_update_cs(SiFiveSPIState *s)
+{
+    int i;
+
+    for (i = 0; i < s->num_cs; i++) {
+        if (s->regs[R_CSDEF] & (1 << i)) {
+            qemu_set_irq(s->cs_lines[i], !(s->regs[R_CSMODE]));
+        }
+    }
+}
+
+static void sifive_spi_update_irq(SiFiveSPIState *s)
+{
+    int level;
+
+    if (fifo8_num_used(&s->tx_fifo) < s->regs[R_TXMARK]) {
+        s->regs[R_IP] |= IP_TXWM;
+    } else {
+        s->regs[R_IP] &= ~IP_TXWM;
+    }
+
+    if (fifo8_num_used(&s->rx_fifo) > s->regs[R_RXMARK]) {
+        s->regs[R_IP] |= IP_RXWM;
+    } else {
+        s->regs[R_IP] &= ~IP_RXWM;
+    }
+
+    level = s->regs[R_IP] & s->regs[R_IE] ? 1 : 0;
+    qemu_set_irq(s->irq, level);
+}
+
+static void sifive_spi_reset(DeviceState *d)
+{
+    SiFiveSPIState *s = SIFIVE_SPI(d);
+
+    memset(s->regs, 0, sizeof(s->regs));
+
+    /* The reset value is high for all implemented CS pins */
+    s->regs[R_CSDEF] = (1 << s->num_cs) - 1;
+
+    /* Populate register with their default value */
+    s->regs[R_SCKDIV] = 0x03;
+    s->regs[R_DELAY0] = 0x1001;
+    s->regs[R_DELAY1] = 0x01;
+
+    sifive_spi_txfifo_reset(s);
+    sifive_spi_rxfifo_reset(s);
+
+    sifive_spi_update_cs(s);
+    sifive_spi_update_irq(s);
+}
+
+static void sifive_spi_flush_txfifo(SiFiveSPIState *s)
+{
+    uint8_t tx;
+    uint8_t rx;
+
+    while (!fifo8_is_empty(&s->tx_fifo)) {
+        tx = fifo8_pop(&s->tx_fifo);
+        rx = ssi_transfer(s->spi, tx);
+
+        if (!fifo8_is_full(&s->rx_fifo)) {
+            if (!(s->regs[R_FMT] & FMT_DIR)) {
+                fifo8_push(&s->rx_fifo, rx);
+            }
+        }
+    }
+}
+
+static bool sifive_spi_is_bad_reg(hwaddr addr, bool allow_reserved)
+{
+    bool bad;
+
+    switch (addr) {
+    /* reserved offsets */
+    case 0x08:
+    case 0x0C:
+    case 0x1C:
+    case 0x20:
+    case 0x24:
+    case 0x30:
+    case 0x34:
+    case 0x38:
+    case 0x3C:
+    case 0x44:
+    case 0x58:
+    case 0x5C:
+    case 0x68:
+    case 0x6C:
+        bad = allow_reserved ? false : true;
+        break;
+    default:
+        bad = false;
+    }
+
+    if (addr >= (SIFIVE_SPI_REG_NUM << 2)) {
+        bad = true;
+    }
+
+    return bad;
+}
+
+static uint64_t sifive_spi_read(void *opaque, hwaddr addr, unsigned int size)
+{
+    SiFiveSPIState *s = opaque;
+    uint32_t r;
+
+    if (sifive_spi_is_bad_reg(addr, true)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: bad read at address 0x%"
+                      HWADDR_PRIx "\n", __func__, addr);
+        return 0;
+    }
+
+    addr >>= 2;
+    switch (addr) {
+    case R_TXDATA:
+        if (fifo8_is_full(&s->tx_fifo)) {
+            return TXDATA_FULL;
+        }
+        r = 0;
+        break;
+
+    case R_RXDATA:
+        if (fifo8_is_empty(&s->rx_fifo)) {
+            return RXDATA_EMPTY;
+        }
+        r = fifo8_pop(&s->rx_fifo);
+        break;
+
+    default:
+        r = s->regs[addr];
+        break;
+    }
+
+    sifive_spi_update_irq(s);
+
+    return r;
+}
+
+static void sifive_spi_write(void *opaque, hwaddr addr,
+                             uint64_t val64, unsigned int size)
+{
+    SiFiveSPIState *s = opaque;
+    uint32_t value = val64;
+
+    if (sifive_spi_is_bad_reg(addr, false)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: bad write at addr=0x%"
+                      HWADDR_PRIx " value=0x%x\n", __func__, addr, value);
+        return;
+    }
+
+    addr >>= 2;
+    switch (addr) {
+    case R_CSID:
+        if (value >= s->num_cs) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csid %d\n",
+                          __func__, value);
+        } else {
+            s->regs[R_CSID] = value;
+            sifive_spi_update_cs(s);
+        }
+        break;
+
+    case R_CSDEF:
+        if (value >= (1 << s->num_cs)) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csdef %x\n",
+                          __func__, value);
+        } else {
+            s->regs[R_CSDEF] = value;
+        }
+        break;
+
+    case R_CSMODE:
+        if (value > 3) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csmode %x\n",
+                          __func__, value);
+        } else {
+            s->regs[R_CSMODE] = value;
+            sifive_spi_update_cs(s);
+        }
+        break;
+
+    case R_TXDATA:
+        if (!fifo8_is_full(&s->tx_fifo)) {
+            fifo8_push(&s->tx_fifo, (uint8_t)value);
+            sifive_spi_flush_txfifo(s);
+        }
+        break;
+
+    case R_RXDATA:
+    case R_IP:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: invalid write to read-only reigster 0x%"
+                      HWADDR_PRIx " with 0x%x\n", __func__, addr << 2, value);
+        break;
+
+    case R_TXMARK:
+    case R_RXMARK:
+        if (value >= FIFO_CAPACITY) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid watermark %d\n",
+                          __func__, value);
+        } else {
+            s->regs[addr] = value;
+        }
+        break;
+
+    case R_FCTRL:
+    case R_FFMT:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: direct-map flash interface unimplemented\n",
+                      __func__);
+        break;
+
+    default:
+        s->regs[addr] = value;
+        break;
+    }
+
+    sifive_spi_update_irq(s);
+}
+
+static const MemoryRegionOps sifive_spi_ops = {
+    .read = sifive_spi_read,
+    .write = sifive_spi_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4
+    }
+};
+
+static void sifive_spi_realize(DeviceState *dev, Error **errp)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    SiFiveSPIState *s = SIFIVE_SPI(dev);
+    int i;
+
+    s->spi = ssi_create_bus(dev, "spi");
+    sysbus_init_irq(sbd, &s->irq);
+
+    s->cs_lines = g_new0(qemu_irq, s->num_cs);
+    for (i = 0; i < s->num_cs; i++) {
+        sysbus_init_irq(sbd, &s->cs_lines[i]);
+    }
+
+    memory_region_init_io(&s->mmio, OBJECT(s), &sifive_spi_ops, s,
+                          TYPE_SIFIVE_SPI, 0x1000);
+    sysbus_init_mmio(sbd, &s->mmio);
+
+    fifo8_create(&s->tx_fifo, FIFO_CAPACITY);
+    fifo8_create(&s->rx_fifo, FIFO_CAPACITY);
+}
+
+static Property sifive_spi_properties[] = {
+    DEFINE_PROP_UINT32("num-cs", SiFiveSPIState, num_cs, 1),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void sifive_spi_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    device_class_set_props(dc, sifive_spi_properties);
+    dc->reset = sifive_spi_reset;
+    dc->realize = sifive_spi_realize;
+}
+
+static const TypeInfo sifive_spi_info = {
+    .name           = TYPE_SIFIVE_SPI,
+    .parent         = TYPE_SYS_BUS_DEVICE,
+    .instance_size  = sizeof(SiFiveSPIState),
+    .class_init     = sifive_spi_class_init,
+};
+
+static void sifive_spi_register_types(void)
+{
+    type_register_static(&sifive_spi_info);
+}
+
+type_init(sifive_spi_register_types)