Re: [Qemu-devel] [PATCH 4/8] introduce dpcd module.

[Peter Crosthwaite <peter.crosthwaite@xilinx.com>]

On Wed, May 13, 2015 at 12:12 PM,  <fred.konrad@greensocs.com> wrote:
> From: KONRAD Frederic <fred.konrad@greensocs.com>
>
> This introduces a DPCD modules. It wires on a aux-bus and can be accessed by
> driver to get lane-speed, etc.
>
> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
> ---
>  hw/display/Makefile.objs |   1 +
>  hw/display/dpcd.c        | 139 +++++++++++++++++++++++++++++++++++++++++++++++
>  hw/display/dpcd.h        |  72 ++++++++++++++++++++++++
>  3 files changed, 212 insertions(+)
>  create mode 100644 hw/display/dpcd.c
>  create mode 100644 hw/display/dpcd.h
>
> diff --git a/hw/display/Makefile.objs b/hw/display/Makefile.objs
> index 3ea106d..f746cec 100644
> --- a/hw/display/Makefile.objs
> +++ b/hw/display/Makefile.objs
> @@ -34,3 +34,4 @@ obj-$(CONFIG_CG3) += cg3.o
>  obj-$(CONFIG_VGA) += vga.o
>
>  common-obj-$(CONFIG_QXL) += qxl.o qxl-logger.o qxl-render.o
> +common-obj-y += dpcd.o
> diff --git a/hw/display/dpcd.c b/hw/display/dpcd.c
> new file mode 100644
> index 0000000..757b65e
> --- /dev/null
> +++ b/hw/display/dpcd.c
> @@ -0,0 +1,139 @@
> +/*
> + * dpcd.c
> + *
> + *  Copyright (C)2015 : GreenSocs Ltd
> + *      http://www.greensocs.com/ , email: info@greensocs.com
> + *
> + *  Developed by :
> + *  Frederic Konrad   <fred.konrad@greensocs.com>
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that 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/>.
> + *
> + */
> +
> +/*
> + * This is a simple AUX slave which emulate a screen connected.
> + */

emulates a connected screen.

> +
> +#include "hw/aux.h"
> +#include "dpcd.h"
> +
> +/* #define DEBUG_DPCD */
> +#ifdef DEBUG_DPCD
> +#define DPRINTF(fmt, ...) do { printf("dpcd: "fmt , ## __VA_ARGS__); } while (0)
> +#else
> +#define DPRINTF(fmt, ...) do {} while (0)
> +#endif
> +

Same comment as before about debug stuffs.

> +struct DPCDState {
> +    AUXSlave parent_obj;
> +
> +    size_t current_reg;

What the actual size of the bus? This should be a fixed width type to match.

> +    /*
> +     * The DCPD is 0x7FFFF length but read as 0 after offset 0x600.
> +     */
> +    uint8_t dpcd_info[0x600];
> +
> +    MemoryRegion iomem;
> +};
> +
> +static void dpcd_realize(DeviceState *dev, Error **errp)
> +{
> +
> +}

Blank realize not needed. Just leave the hook unset.

> +
> +static uint64_t aux_read(void *opaque, hwaddr offset, unsigned size)

The fn name should match the name of the bus and not the attached dev.

> +{
> +    uint64_t ret;
> +    DPCDState *e = DPCD(opaque);
> +    assert(size == 1);

Is this a limitation of aux or the device? In the former, I would just
delete assertion. For the later it should be a GUEST_ERROR or UNIMP.

> +
> +    if (offset <= 0x600) {
> +        ret = e->dpcd_info[offset];
> +    } else {
> +        ret = 0;

GUEST_ERROR?

> +    }
> +
> +    DPRINTF("read %u @0x%8.8lX\n", (uint8_t)ret, offset);
> +    return ret;
> +}
> +
> +static void aux_write(void *opaque, hwaddr offset, uint64_t value,
> +                      unsigned size)
> +{
> +    DPCDState *e = DPCD(opaque);
> +    assert(size == 1);
> +
> +    DPRINTF("write %u @0x%8.8lX\n", (uint8_t)value, offset);
> +
> +    if (offset <= 0x600) {
> +        e->dpcd_info[offset] = value;
> +    }
> +}
> +
> +static const MemoryRegionOps aux_ops = {
> +    .read = aux_read,
> +    .write = aux_write

Chould you set your access width restrictions here instead of the assert?

> +};
> +
> +static void aux_edid_init(Object *obj)
> +{
> +    /*
> +     * Create a default DPCD..
> +     */
> +    DPCDState *s = DPCD(obj);
> +
> +    memset(&(s->dpcd_info), 0, sizeof(s->dpcd_info));
> +
> +    s->current_reg = 0;
> +
> +    s->dpcd_info[0x00] = DPCD_REV_1_0;
> +    s->dpcd_info[0x01] = DPCD_5_4GBPS;
> +    s->dpcd_info[0x02] = 0x1;
> +    s->dpcd_info[0x08] = DPCD_EDID_PRESENT;
> +    s->dpcd_info[0x09] = 0xFF;
> +
> +    /* CR DONE, CE DONE, SYMBOL LOCKED.. */
> +    s->dpcd_info[0x202] = 0x07;
> +    /* INTERLANE_ALIGN_DONE.. */
> +    s->dpcd_info[0x204] = 0x01;
> +    s->dpcd_info[0x205] = 0x01;
> +

State setup should be handled by a reset callback.

> +    /*
> +     * Create the address-map.
> +     */
> +    memory_region_init_io(&s->iomem, obj, &aux_ops, s, TYPE_DPCD, 0x7FFFF);
> +    aux_init_mmio(AUX_SLAVE(obj), &s->iomem);
> +}
> +
> +static void aux_edid_class_init(ObjectClass *oc, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +    dc->realize = dpcd_realize;

reset and vmsd hooks needed.

> +}
> +
> +static const TypeInfo aux_edid_info = {
> +    .name          = TYPE_DPCD,
> +    .parent        = TYPE_AUX_SLAVE,
> +    .instance_size = sizeof(DPCDState),
> +    .instance_init = aux_edid_init,
> +    .class_init    = aux_edid_class_init,
> +};
> +
> +static void aux_edid_register_types(void)
> +{
> +    type_register_static(&aux_edid_info);
> +}
> +
> +type_init(aux_edid_register_types)
> diff --git a/hw/display/dpcd.h b/hw/display/dpcd.h
> new file mode 100644
> index 0000000..cd22258
> --- /dev/null
> +++ b/hw/display/dpcd.h
> @@ -0,0 +1,72 @@
> +/*
> + * dpcd.h
> + *
> + *  Copyright (C)2015 : GreenSocs Ltd
> + *      http://www.greensocs.com/ , email: info@greensocs.com
> + *
> + *  Developed by :
> + *  Frederic Konrad   <fred.konrad@greensocs.com>
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that 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/>.
> + *
> + */
> +
> +#ifndef DPCD_H
> +#define DPCD_H
> +
> +typedef struct DPCDState DPCDState;
> +
> +#define TYPE_DPCD "dpcd"
> +#define DPCD(obj) OBJECT_CHECK(DPCDState, (obj), TYPE_DPCD)
> +
> +/* DCPD Revision. */
> +#define DPCD_REV_1_0 0x10
> +#define DPCD_REV_1_1 0x11
> +
> +/* DCPD Max Link Rate. */
> +#define DPCD_1_62GBPS 0x06
> +#define DPCD_2_7GBPS 0x0A
> +#define DPCD_5_4GBPS 0x14
> +
> +/* DCPD Max down spread. */
> +#define DPCD_UP_TO_0_5 0x01
> +#define DPCD_NO_AUX_HANDSHAKE_LINK_TRAINING 0x40
> +
> +/* DCPD Downstream port type. */
> +#define DPCD_DISPLAY_PORT 0x00
> +#define DPCD_ANALOG 0x02
> +#define DPCD_DVI_HDMI 0x04
> +#define DPCD_OTHER 0x06
> +

Tab constants out to consistent tab stop for readability.

Regards,
Peter

> +/* DPCD Format conversion. */
> +#define DPCD_FORMAT_CONVERSION 0x08
> +
> +/* Main link channel coding. */
> +#define DPCD_ANSI_8B_10B 0x01
> +
> +/* Down stream port count. */
> +#define DPCD_OUI_SUPPORTED 0x80
> +
> +/* Receiver port capability. */
> +#define DPCD_EDID_PRESENT 0x02
> +#define DPCD_ASSOCIATED_TO_PRECEDING_PORT 0x04
> +
> +/* Down stream port capability. */
> +#define DPCD_CAP_DISPLAY_PORT 0x000
> +#define DPCD_CAP_ANALOG_VGA 0x001
> +#define DPCD_CAP_DVI 0x002
> +#define DPCD_CAP_HDMI 0x003
> +#define DPCD_CAP_OTHER 0x100
> +
> +#endif /* !DPCD_H */
> --
> 1.9.0
>
>