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linux-next/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
Laurent Pinchart a25b988ff8 drm/bridge: Extend bridge API to disable connector creation 
Most bridge drivers create a DRM connector to model the connector at the
output of the bridge. This model is historical and has worked pretty
well so far, but causes several issues:

- It prevents supporting more complex display pipelines where DRM
connector operations are split over multiple components. For instance a
pipeline with a bridge connected to the DDC signals to read EDID data,
and another one connected to the HPD signal to detect connection and
disconnection, will not be possible to support through this model.

- It requires every bridge driver to implement similar connector
handling code, resulting in code duplication.

- It assumes that a bridge will either be wired to a connector or to
another bridge, but doesn't support bridges that can be used in both
positions very well (although there is some ad-hoc support for this in
the analogix_dp bridge driver).

In order to solve these issues, ownership of the connector should be
moved to the display controller driver (where it can be implemented
using helpers provided by the core).

Extend the bridge API to allow disabling connector creation in bridge
drivers as a first step towards the new model. The new flags argument to
the bridge .attach() operation allows instructing the bridge driver to
skip creating a connector. Unconditionally set the new flags argument to
0 for now to keep the existing behaviour, and modify all existing bridge
drivers to return an error when connector creation is not requested as
they don't support this feature yet.

The change is based on the following semantic patch, with manual review
and edits.

@ rule1 @
identifier funcs;
identifier fn;
@@
 struct drm_bridge_funcs funcs = {
 	...,
 	.attach = fn
 };

@ depends on rule1 @
identifier rule1.fn;
identifier bridge;
statement S, S1;
@@
 int fn(
 	struct drm_bridge *bridge
+	, enum drm_bridge_attach_flags flags
 )
 {
 	... when != S
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	S1
 	...
 }

@ depends on rule1 @
identifier rule1.fn;
identifier bridge, flags;
expression E1, E2, E3;
@@
 int fn(
 	struct drm_bridge *bridge,
 	enum drm_bridge_attach_flags flags
 ) {
 <...
 drm_bridge_attach(E1, E2, E3
+	, flags
 )
 ...>
 }

@@
expression E1, E2, E3;
@@
 drm_bridge_attach(E1, E2, E3
+	, 0
 )

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-10-laurent.pinchart@ideasonboard.com
2020-02-26 13:31:23 +02:00

425 lines
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
* Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)
* Copyright (c) 2017, Collabora Ltd.
* Copyright (c) 2017, General Electric Company
* This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
* display bridge of the GE B850v3. There are two physical bridges on the video
* signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
* physical bridges are automatically configured by the input video signal, and
* the driver has no access to the video processing pipeline. The driver is
* only needed to read EDID from the STDP2690 and to handle HPD events from the
* STDP4028. The driver communicates with both bridges over i2c. The video
* signal pipeline is as follows:
*
* Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
*/
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_bridge.h>
#include <drm/drm_edid.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>
#define EDID_EXT_BLOCK_CNT 0x7E
#define STDP4028_IRQ_OUT_CONF_REG 0x02
#define STDP4028_DPTX_IRQ_EN_REG 0x3C
#define STDP4028_DPTX_IRQ_STS_REG 0x3D
#define STDP4028_DPTX_STS_REG 0x3E
#define STDP4028_DPTX_DP_IRQ_EN 0x1000
#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
#define STDP4028_DPTX_IRQ_CONFIG \
(STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)
#define STDP4028_DPTX_HOTPLUG_STS 0x0200
#define STDP4028_DPTX_LINK_STS 0x1000
#define STDP4028_CON_STATE_CONNECTED \
(STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)
#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
#define STDP4028_DPTX_LINK_CH_STS 0x2000
#define STDP4028_DPTX_IRQ_CLEAR \
(STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)
static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);
struct ge_b850v3_lvds {
struct drm_connector connector;
struct drm_bridge bridge;
struct i2c_client *stdp4028_i2c;
struct i2c_client *stdp2690_i2c;
struct edid *edid;
};
static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;
static u8 *stdp2690_get_edid(struct i2c_client *client)
{
struct i2c_adapter *adapter = client->adapter;
unsigned char start = 0x00;
unsigned int total_size;
u8 *block = kmalloc(EDID_LENGTH, GFP_KERNEL);
struct i2c_msg msgs[] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = &start,
}, {
.addr = client->addr,
.flags = I2C_M_RD,
.len = EDID_LENGTH,
.buf = block,
}
};
if (!block)
return NULL;
if (i2c_transfer(adapter, msgs, 2) != 2) {
DRM_ERROR("Unable to read EDID.\n");
goto err;
}
if (!drm_edid_block_valid(block, 0, false, NULL)) {
DRM_ERROR("Invalid EDID data\n");
goto err;
}
total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH;
if (total_size > EDID_LENGTH) {
kfree(block);
block = kmalloc(total_size, GFP_KERNEL);
if (!block)
return NULL;
/* Yes, read the entire buffer, and do not skip the first
* EDID_LENGTH bytes.
*/
start = 0x00;
msgs[1].len = total_size;
msgs[1].buf = block;
if (i2c_transfer(adapter, msgs, 2) != 2) {
DRM_ERROR("Unable to read EDID extension blocks.\n");
goto err;
}
if (!drm_edid_block_valid(block, 1, false, NULL)) {
DRM_ERROR("Invalid EDID data\n");
goto err;
}
}
return block;
err:
kfree(block);
return NULL;
}
static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
{
struct i2c_client *client;
int num_modes = 0;
client = ge_b850v3_lvds_ptr->stdp2690_i2c;
kfree(ge_b850v3_lvds_ptr->edid);
ge_b850v3_lvds_ptr->edid = (struct edid *)stdp2690_get_edid(client);
if (ge_b850v3_lvds_ptr->edid) {
drm_connector_update_edid_property(connector,
ge_b850v3_lvds_ptr->edid);
num_modes = drm_add_edid_modes(connector,
ge_b850v3_lvds_ptr->edid);
}
return num_modes;
}
static enum drm_mode_status ge_b850v3_lvds_mode_valid(
struct drm_connector *connector, struct drm_display_mode *mode)
{
return MODE_OK;
}
static const struct
drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
.get_modes = ge_b850v3_lvds_get_modes,
.mode_valid = ge_b850v3_lvds_mode_valid,
};
static enum drm_connector_status ge_b850v3_lvds_detect(
struct drm_connector *connector, bool force)
{
struct i2c_client *stdp4028_i2c =
ge_b850v3_lvds_ptr->stdp4028_i2c;
s32 link_state;
link_state = i2c_smbus_read_word_data(stdp4028_i2c,
STDP4028_DPTX_STS_REG);
if (link_state == STDP4028_CON_STATE_CONNECTED)
return connector_status_connected;
if (link_state == 0)
return connector_status_disconnected;
return connector_status_unknown;
}
static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
.fill_modes = drm_helper_probe_single_connector_modes,
.detect = ge_b850v3_lvds_detect,
.destroy = drm_connector_cleanup,
.reset = drm_atomic_helper_connector_reset,
.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};
static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
{
struct i2c_client *stdp4028_i2c
= ge_b850v3_lvds_ptr->stdp4028_i2c;
i2c_smbus_write_word_data(stdp4028_i2c,
STDP4028_DPTX_IRQ_STS_REG,
STDP4028_DPTX_IRQ_CLEAR);
if (ge_b850v3_lvds_ptr->connector.dev)
drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->connector.dev);
return IRQ_HANDLED;
}
static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
enum drm_bridge_attach_flags flags)
{
struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
struct i2c_client *stdp4028_i2c
= ge_b850v3_lvds_ptr->stdp4028_i2c;
int ret;
if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
DRM_ERROR("Fix bridge driver to make connector optional!");
return -EINVAL;
}
if (!bridge->encoder) {
DRM_ERROR("Parent encoder object not found");
return -ENODEV;
}
connector->polled = DRM_CONNECTOR_POLL_HPD;
drm_connector_helper_add(connector,
&ge_b850v3_lvds_connector_helper_funcs);
ret = drm_connector_init(bridge->dev, connector,
&ge_b850v3_lvds_connector_funcs,
DRM_MODE_CONNECTOR_DisplayPort);
if (ret) {
DRM_ERROR("Failed to initialize connector with drm\n");
return ret;
}
ret = drm_connector_attach_encoder(connector, bridge->encoder);
if (ret)
return ret;
/* Configures the bridge to re-enable interrupts after each ack. */
i2c_smbus_write_word_data(stdp4028_i2c,
STDP4028_IRQ_OUT_CONF_REG,
STDP4028_DPTX_DP_IRQ_EN);
/* Enable interrupts */
i2c_smbus_write_word_data(stdp4028_i2c,
STDP4028_DPTX_IRQ_EN_REG,
STDP4028_DPTX_IRQ_CONFIG);
return 0;
}
static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
.attach = ge_b850v3_lvds_attach,
};
static int ge_b850v3_lvds_init(struct device *dev)
{
mutex_lock(&ge_b850v3_lvds_dev_mutex);
if (ge_b850v3_lvds_ptr)
goto success;
ge_b850v3_lvds_ptr = devm_kzalloc(dev,
sizeof(*ge_b850v3_lvds_ptr),
GFP_KERNEL);
if (!ge_b850v3_lvds_ptr) {
mutex_unlock(&ge_b850v3_lvds_dev_mutex);
return -ENOMEM;
}
success:
mutex_unlock(&ge_b850v3_lvds_dev_mutex);
return 0;
}
static void ge_b850v3_lvds_remove(void)
{
mutex_lock(&ge_b850v3_lvds_dev_mutex);
/*
* This check is to avoid both the drivers
* removing the bridge in their remove() function
*/
if (!ge_b850v3_lvds_ptr)
goto out;
drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);
kfree(ge_b850v3_lvds_ptr->edid);
ge_b850v3_lvds_ptr = NULL;
out:
mutex_unlock(&ge_b850v3_lvds_dev_mutex);
}
static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c,
const struct i2c_device_id *id)
{
struct device *dev = &stdp4028_i2c->dev;
ge_b850v3_lvds_init(dev);
ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);
/* drm bridge initialization */
ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);
/* Clear pending interrupts since power up. */
i2c_smbus_write_word_data(stdp4028_i2c,
STDP4028_DPTX_IRQ_STS_REG,
STDP4028_DPTX_IRQ_CLEAR);
if (!stdp4028_i2c->irq)
return 0;
return devm_request_threaded_irq(&stdp4028_i2c->dev,
stdp4028_i2c->irq, NULL,
ge_b850v3_lvds_irq_handler,
IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
}
static int stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
{
ge_b850v3_lvds_remove();
return 0;
}
static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
{"stdp4028_ge_fw", 0},
{},
};
MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);
static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
{},
};
MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);
static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
.id_table = stdp4028_ge_b850v3_fw_i2c_table,
.probe = stdp4028_ge_b850v3_fw_probe,
.remove = stdp4028_ge_b850v3_fw_remove,
.driver = {
.name = "stdp4028-ge-b850v3-fw",
.of_match_table = stdp4028_ge_b850v3_fw_match,
},
};
static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c,
const struct i2c_device_id *id)
{
struct device *dev = &stdp2690_i2c->dev;
ge_b850v3_lvds_init(dev);
ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);
return 0;
}
static int stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
{
ge_b850v3_lvds_remove();
return 0;
}
static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
{"stdp2690_ge_fw", 0},
{},
};
MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);
static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
{},
};
MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);
static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
.id_table = stdp2690_ge_b850v3_fw_i2c_table,
.probe = stdp2690_ge_b850v3_fw_probe,
.remove = stdp2690_ge_b850v3_fw_remove,
.driver = {
.name = "stdp2690-ge-b850v3-fw",
.of_match_table = stdp2690_ge_b850v3_fw_match,
},
};
static int __init stdpxxxx_ge_b850v3_init(void)
{
int ret;
ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
if (ret)
return ret;
return i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
}
module_init(stdpxxxx_ge_b850v3_init);
static void __exit stdpxxxx_ge_b850v3_exit(void)
{
i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
}
module_exit(stdpxxxx_ge_b850v3_exit);
MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
MODULE_LICENSE("GPL v2");
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