hw/misc: Add support for ADC controller in Xilinx Zynq 7000

Add support for the Xilinx XADC core used in Zynq 7000.

References:
- Zynq-7000 All Programmable SoC Technical Reference Manual
- 7 Series FPGAs and Zynq-7000 All Programmable SoC XADC
  Dual 12-Bit 1 MSPS Analog-to-Digital Converter

Tested with Linux using QEMU machine xilinx-zynq-a9 with devicetree
files zynq-zc702.dtb and zynq-zc706.dtb, and kernel configuration
multi_v7_defconfig.

Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[ PC changes:
  * Changed macro names to match TRM where possible
  * Made programmers model macro scheme consistent
  * Dropped XADC_ZYNQ_ prefix on local macros
  * Fix ALM field width
  * Update threshold-comparison interrupts in _update_ints()
  * factored out DFIFO pushes into helper. Renamed to "push/pop"
  * Changed xadc_reg to 10 bits and added OOB check.
  * Reduced scope of MCTL reset to just stop channel coms.
  * Added dummy read data to write commands
  * Changed _ to - seperators in string names and filenames
  * Dropped ------------ in header comment
  * Catchall'ed _update_ints() in _write handler.
  * Minor whitespace changes.
  * Use ZYNQ_XADC_FIFO_DEPTH instead of ARRAY_SIZE()
]
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 302 insertions, 0 deletions

diff --git a/hw/misc/zynq-xadc.c b/hw/misc/zynq-xadc.c
new file mode 100644
index 0000000000..1a32595455
--- /dev/null
+++ b/hw/misc/zynq-xadc.c
@@ -0,0 +1,302 @@
+/*
+ * ADC registers for Xilinx Zynq Platform
+ *
+ * Copyright (c) 2015 Guenter Roeck
+ * Based on hw/misc/zynq_slcr.c, written by Michal Simek
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * 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 "hw/hw.h"
+#include "hw/misc/zynq-xadc.h"
+#include "qemu/timer.h"
+#include "sysemu/sysemu.h"
+
+enum {
+    CFG                = 0x000 / 4,
+    INT_STS,
+    INT_MASK,
+    MSTS,
+    CMDFIFO,
+    RDFIFO,
+    MCTL,
+};
+
+#define CFG_ENABLE              BIT(31)
+#define CFG_CFIFOTH_SHIFT       20
+#define CFG_CFIFOTH_LENGTH      4
+#define CFG_DFIFOTH_SHIFT       16
+#define CFG_DFIFOTH_LENGTH      4
+#define CFG_WEDGE               BIT(13)
+#define CFG_REDGE               BIT(12)
+#define CFG_TCKRATE_SHIFT       8
+#define CFG_TCKRATE_LENGTH      2
+
+#define CFG_TCKRATE_DIV(x)      (0x1 << (x - 1))
+
+#define CFG_IGAP_SHIFT          0
+#define CFG_IGAP_LENGTH         5
+
+#define INT_CFIFO_LTH           BIT(9)
+#define INT_DFIFO_GTH           BIT(8)
+#define INT_OT                  BIT(7)
+#define INT_ALM_SHIFT           0
+#define INT_ALM_LENGTH          7
+#define INT_ALM_MASK            (((1 << INT_ALM_LENGTH) - 1) << INT_ALM_SHIFT)
+
+#define INT_ALL (INT_CFIFO_LTH | INT_DFIFO_GTH | INT_OT | INT_ALM_MASK)
+
+#define MSTS_CFIFO_LVL_SHIFT    16
+#define MSTS_CFIFO_LVL_LENGTH   4
+#define MSTS_DFIFO_LVL_SHIFT    12
+#define MSTS_DFIFO_LVL_LENGTH   4
+#define MSTS_CFIFOF             BIT(11)
+#define MSTS_CFIFOE             BIT(10)
+#define MSTS_DFIFOF             BIT(9)
+#define MSTS_DFIFOE             BIT(8)
+#define MSTS_OT                 BIT(7)
+#define MSTS_ALM_SHIFT          0
+#define MSTS_ALM_LENGTH         7
+
+#define MCTL_RESET              BIT(4)
+
+#define CMD_NOP                 0x00
+#define CMD_READ                0x01
+#define CMD_WRITE               0x02
+
+static void zynq_xadc_update_ints(ZynqXADCState *s)
+{
+
+    /* We are fast, commands are actioned instantly so the CFIFO is always
+     * empty (and below threshold).
+     */
+    s->regs[INT_STS] |= INT_CFIFO_LTH;
+
+    if (s->xadc_dfifo_entries >
+        extract32(s->regs[CFG], CFG_DFIFOTH_SHIFT, CFG_DFIFOTH_LENGTH)) {
+        s->regs[INT_STS] |= INT_DFIFO_GTH;
+    }
+
+    qemu_set_irq(s->qemu_irq, !!(s->regs[INT_STS] & ~s->regs[INT_MASK]));
+}
+
+static void zynq_xadc_reset(DeviceState *d)
+{
+    ZynqXADCState *s = ZYNQ_XADC(d);
+
+    s->regs[CFG] = 0x14 << CFG_IGAP_SHIFT |
+                   CFG_TCKRATE_DIV(4) << CFG_TCKRATE_SHIFT | CFG_REDGE;
+    s->regs[INT_STS] = INT_CFIFO_LTH;
+    s->regs[INT_MASK] = 0xffffffff;
+    s->regs[CMDFIFO] = 0;
+    s->regs[RDFIFO] = 0;
+    s->regs[MCTL] = MCTL_RESET;
+
+    memset(s->xadc_regs, 0, sizeof(s->xadc_regs));
+    memset(s->xadc_dfifo, 0, sizeof(s->xadc_dfifo));
+    s->xadc_dfifo_entries = 0;
+
+    zynq_xadc_update_ints(s);
+}
+
+static uint16_t xadc_pop_dfifo(ZynqXADCState *s)
+{
+    uint16_t rv = s->xadc_dfifo[0];
+    int i;
+
+    if (s->xadc_dfifo_entries > 0) {
+        s->xadc_dfifo_entries--;
+    }
+    for (i = 0; i < s->xadc_dfifo_entries; i++) {
+        s->xadc_dfifo[i] = s->xadc_dfifo[i + 1];
+    }
+    s->xadc_dfifo[s->xadc_dfifo_entries] = 0;
+    zynq_xadc_update_ints(s);
+    return rv;
+}
+
+static void xadc_push_dfifo(ZynqXADCState *s, uint16_t regval)
+{
+    if (s->xadc_dfifo_entries < ZYNQ_XADC_FIFO_DEPTH) {
+        s->xadc_dfifo[s->xadc_dfifo_entries++] = s->xadc_read_reg_previous;
+    }
+    s->xadc_read_reg_previous = regval;
+    zynq_xadc_update_ints(s);
+}
+
+static bool zynq_xadc_check_offset(hwaddr offset, bool rnw)
+{
+    switch (offset) {
+    case CFG:
+    case INT_MASK:
+    case INT_STS:
+    case MCTL:
+        return true;
+    case RDFIFO:
+    case MSTS:
+        return rnw;     /* read only */
+    case CMDFIFO:
+        return !rnw;    /* write only */
+    default:
+        return false;
+    }
+}
+
+static uint64_t zynq_xadc_read(void *opaque, hwaddr offset, unsigned size)
+{
+    ZynqXADCState *s = opaque;
+    int reg = offset / 4;
+    uint32_t rv = 0;
+
+    if (!zynq_xadc_check_offset(reg, true)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "zynq_xadc: Invalid read access to "
+                      "addr %" HWADDR_PRIx "\n", offset);
+        return 0;
+    }
+
+    switch (reg) {
+    case CFG:
+    case INT_MASK:
+    case INT_STS:
+    case MCTL:
+        rv = s->regs[reg];
+        break;
+    case MSTS:
+        rv = MSTS_CFIFOE;
+        rv |= s->xadc_dfifo_entries << MSTS_DFIFO_LVL_SHIFT;
+        if (!s->xadc_dfifo_entries) {
+            rv |= MSTS_DFIFOE;
+        } else if (s->xadc_dfifo_entries == ZYNQ_XADC_FIFO_DEPTH) {
+            rv |= MSTS_DFIFOF;
+        }
+        break;
+    case RDFIFO:
+        rv = xadc_pop_dfifo(s);
+        break;
+    }
+    return rv;
+}
+
+static void zynq_xadc_write(void *opaque, hwaddr offset, uint64_t val,
+                            unsigned size)
+{
+    ZynqXADCState *s = (ZynqXADCState *)opaque;
+    int reg = offset / 4;
+    int xadc_reg;
+    int xadc_cmd;
+    int xadc_data;
+
+    if (!zynq_xadc_check_offset(reg, false)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "zynq_xadc: Invalid write access "
+                      "to addr %" HWADDR_PRIx "\n", offset);
+        return;
+    }
+
+    switch (reg) {
+    case CFG:
+        s->regs[CFG] = val;
+        break;
+    case INT_STS:
+        s->regs[INT_STS] &= ~val;
+        break;
+    case INT_MASK:
+        s->regs[INT_MASK] = val & INT_ALL;
+        break;
+    case CMDFIFO:
+        xadc_cmd  = extract32(val, 26,  4);
+        xadc_reg  = extract32(val, 16, 10);
+        xadc_data = extract32(val,  0, 16);
+
+        if (s->regs[MCTL] & MCTL_RESET) {
+            qemu_log_mask(LOG_GUEST_ERROR, "zynq_xadc: Sending command "
+                          "while comm channel held in reset: %" PRIx32 "\n",
+                          (uint32_t) val);
+            break;
+        }
+
+        if (xadc_reg > ZYNQ_XADC_NUM_ADC_REGS && xadc_cmd != CMD_NOP) {
+            qemu_log_mask(LOG_GUEST_ERROR, "read/write op to invalid xadc "
+                          "reg 0x%x\n", xadc_reg);
+            break;
+        }
+
+        switch (xadc_cmd) {
+        case CMD_READ:
+            xadc_push_dfifo(s, s->xadc_regs[xadc_reg]);
+            break;
+        case CMD_WRITE:
+            s->xadc_regs[xadc_reg] = xadc_data;
+            /* fallthrough */
+        case CMD_NOP:
+            xadc_push_dfifo(s, 0);
+            break;
+        }
+        break;
+    case MCTL:
+        s->regs[MCTL] = val & 0x00fffeff;
+        break;
+    }
+    zynq_xadc_update_ints(s);
+}
+
+static const MemoryRegionOps xadc_ops = {
+    .read = zynq_xadc_read,
+    .write = zynq_xadc_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static void zynq_xadc_init(Object *obj)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+    ZynqXADCState *s = ZYNQ_XADC(obj);
+
+    memory_region_init_io(&s->iomem, obj, &xadc_ops, s, "zynq-xadc",
+                          ZYNQ_XADC_MMIO_SIZE);
+    sysbus_init_mmio(sbd, &s->iomem);
+    sysbus_init_irq(sbd, &s->qemu_irq);
+}
+
+static const VMStateDescription vmstate_zynq_xadc = {
+    .name = "zynq-xadc",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32_ARRAY(regs, ZynqXADCState, ZYNQ_XADC_NUM_IO_REGS),
+        VMSTATE_UINT16_ARRAY(xadc_regs, ZynqXADCState,
+                             ZYNQ_XADC_NUM_ADC_REGS),
+        VMSTATE_UINT16_ARRAY(xadc_dfifo, ZynqXADCState,
+                             ZYNQ_XADC_FIFO_DEPTH),
+        VMSTATE_UINT16(xadc_read_reg_previous, ZynqXADCState),
+        VMSTATE_UINT16(xadc_dfifo_entries, ZynqXADCState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void zynq_xadc_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->vmsd = &vmstate_zynq_xadc;
+    dc->reset = zynq_xadc_reset;
+}
+
+static const TypeInfo zynq_xadc_info = {
+    .class_init = zynq_xadc_class_init,
+    .name  = TYPE_ZYNQ_XADC,
+    .parent = TYPE_SYS_BUS_DEVICE,
+    .instance_size  = sizeof(ZynqXADCState),
+    .instance_init = zynq_xadc_init,
+};
+
+static void zynq_xadc_register_types(void)
+{
+    type_register_static(&zynq_xadc_info);
+}
+
+type_init(zynq_xadc_register_types)