qemu-e2k/hw/display/i2c-ddc.c

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/* A simple I2C slave for returning monitor EDID data via DDC.
*
* Copyright (c) 2011 Linaro Limited
* Written by Peter Maydell
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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/>.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "hw/i2c/i2c.h"
#include "hw/qdev-properties.h"
#include "migration/vmstate.h"
#include "hw/display/i2c-ddc.h"
#ifndef DEBUG_I2CDDC
#define DEBUG_I2CDDC 0
#endif
#define DPRINTF(fmt, ...) do { \
if (DEBUG_I2CDDC) { \
qemu_log("i2c-ddc: " fmt , ## __VA_ARGS__); \
} \
maint: Fix macros with broken 'do/while(0); ' usage The point of writing a macro embedded in a 'do { ... } while (0)' loop (particularly if the macro has multiple statements or would otherwise end with an 'if' statement) is so that the macro can be used as a drop-in statement with the caller supplying the trailing ';'. Although our coding style frowns on brace-less 'if': if (cond) statement; else something else; that is the classic case where failure to use do/while(0) wrapping would cause the 'else' to pair with any embedded 'if' in the macro rather than the intended outer 'if'. But conversely, if the macro includes an embedded ';', then the same brace-less coding style would now have two statements, making the 'else' a syntax error rather than pairing with the outer 'if'. Thus, even though our coding style with required braces is not impacted, ending a macro with ';' makes our code harder to port to projects that use brace-less styles. The change should have no semantic impact. I was not able to fully compile-test all of the changes (as some of them are examples of the ugly bit-rotting debug print statements that are completely elided by default, and I didn't want to recompile with the necessary -D witnesses - cleaning those up is left as a bite-sized task for another day); I did, however, audit that for all files touched, all callers of the changed macros DID supply a trailing ';' at the callsite, and did not appear to be used as part of a brace-less conditional. Found mechanically via: $ git grep -B1 'while (0);' | grep -A1 \\\\ Signed-off-by: Eric Blake <eblake@redhat.com> Acked-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Message-Id: <20171201232433.25193-7-eblake@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-12-02 00:24:32 +01:00
} while (0)
static void i2c_ddc_reset(DeviceState *ds)
{
I2CDDCState *s = I2CDDC(ds);
s->firstbyte = false;
s->reg = 0;
}
static int i2c_ddc_event(I2CSlave *i2c, enum i2c_event event)
{
I2CDDCState *s = I2CDDC(i2c);
if (event == I2C_START_SEND) {
s->firstbyte = true;
}
return 0;
}
static uint8_t i2c_ddc_rx(I2CSlave *i2c)
{
I2CDDCState *s = I2CDDC(i2c);
int value;
value = s->edid_blob[s->reg % sizeof(s->edid_blob)];
s->reg++;
return value;
}
static int i2c_ddc_tx(I2CSlave *i2c, uint8_t data)
{
I2CDDCState *s = I2CDDC(i2c);
if (s->firstbyte) {
s->reg = data;
s->firstbyte = false;
DPRINTF("[EDID] Written new pointer: %u\n", data);
return 0;
}
/* Ignore all writes */
s->reg++;
return 0;
}
static void i2c_ddc_init(Object *obj)
{
I2CDDCState *s = I2CDDC(obj);
qemu_edid_generate(s->edid_blob, sizeof(s->edid_blob), &s->edid_info);
}
static const VMStateDescription vmstate_i2c_ddc = {
.name = TYPE_I2CDDC,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_BOOL(firstbyte, I2CDDCState),
VMSTATE_UINT8(reg, I2CDDCState),
VMSTATE_END_OF_LIST()
}
};
static Property i2c_ddc_properties[] = {
DEFINE_EDID_PROPERTIES(I2CDDCState, edid_info),
DEFINE_PROP_END_OF_LIST(),
};
static void i2c_ddc_class_init(ObjectClass *oc, void *data)
{
DeviceClass *dc = DEVICE_CLASS(oc);
I2CSlaveClass *isc = I2C_SLAVE_CLASS(oc);
dc->reset = i2c_ddc_reset;
dc->vmsd = &vmstate_i2c_ddc;
device_class_set_props(dc, i2c_ddc_properties);
isc->event = i2c_ddc_event;
isc->recv = i2c_ddc_rx;
isc->send = i2c_ddc_tx;
}
static TypeInfo i2c_ddc_info = {
.name = TYPE_I2CDDC,
.parent = TYPE_I2C_SLAVE,
.instance_size = sizeof(I2CDDCState),
.instance_init = i2c_ddc_init,
.class_init = i2c_ddc_class_init
};
static void ddc_register_devices(void)
{
type_register_static(&i2c_ddc_info);
}
type_init(ddc_register_devices);