/*
* Copyright © 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <drm/drm_dp_dual_mode_helper.h>
#include <drm/drmP.h>
/**
* DOC: dp dual mode helpers
*
* Helper functions to deal with DP dual mode (aka. DP++) adaptors.
*
* Type 1:
* Adaptor registers (if any) and the sink DDC bus may be accessed via I2C.
*
* Type 2:
* Adaptor registers and sink DDC bus can be accessed either via I2C or
* I2C-over-AUX. Source devices may choose to implement either of these
* access methods.
*/
#define DP_DUAL_MODE_SLAVE_ADDRESS 0x40
/**
* drm_dp_dual_mode_read - Read from the DP dual mode adaptor register(s)
* @adapter: I2C adapter for the DDC bus
* @offset: register offset
* @buffer: buffer for return data
* @size: sizo of the buffer
*
* Reads @size bytes from the DP dual mode adaptor registers
* starting at @offset.
*
* Returns:
* 0 on success, negative error code on failure
*/
ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
u8 offset, void *buffer, size_t size)
{
struct i2c_msg msgs[] = {
{
.addr = DP_DUAL_MODE_SLAVE_ADDRESS,
.flags = 0,
.len = 1,
.buf = &offset,
},
{
.addr = DP_DUAL_MODE_SLAVE_ADDRESS,
.flags = I2C_M_RD,
.len = size,
.buf = buffer,
},
};
int ret;
ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
if (ret < 0)
return ret;
if (ret != ARRAY_SIZE(msgs))
return -EPROTO;
return 0;
}
EXPORT_SYMBOL(drm_dp_dual_mode_read);
/**
* drm_dp_dual_mode_write - Write to the DP dual mode adaptor register(s)
* @adapter: I2C adapter for the DDC bus
* @offset: register offset
* @buffer: buffer for write data
* @size: sizo of the buffer
*
* Writes @size bytes to the DP dual mode adaptor registers
* starting at @offset.
*
* Returns:
* 0 on success, negative error code on failure
*/
ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
u8 offset, const void *buffer, size_t size)
{
struct i2c_msg msg = {
.addr = DP_DUAL_MODE_SLAVE_ADDRESS,
.flags = 0,
.len = 1 + size,
.buf = NULL,
};
void *data;
int ret;
data = kmalloc(msg.len, GFP_TEMPORARY);
if (!data)
return -ENOMEM;
msg.buf = data;
memcpy(data
+ 1, buffer
, size
);
ret = i2c_transfer(adapter, &msg, 1);
kfree(data);
if (ret < 0)
return ret;
if (ret != 1)
return -EPROTO;
return 0;
}
EXPORT_SYMBOL(drm_dp_dual_mode_write);
static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
{
static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
"DP-HDMI ADAPTOR\x04";
return memcmp(hdmi_id
, dp_dual_mode_hdmi_id
, sizeof(dp_dual_mode_hdmi_id)) == 0;
}
static bool is_type2_adaptor(uint8_t adaptor_id)
{
return adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
DP_DUAL_MODE_REV_TYPE2);
}
/**
* drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
* @adapter: I2C adapter for the DDC bus
*
* Attempt to identify the type of the DP dual mode adaptor used.
*
* Note that when the answer is @DRM_DP_DUAL_MODE_UNKNOWN it's not
* certain whether we're dealing with a native HDMI port or
* a type 1 DVI dual mode adaptor. The driver will have to use
* some other hardware/driver specific mechanism to make that
* distinction.
*
* Returns:
* The type of the DP dual mode adaptor used
*/
enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
{
char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] = {};
uint8_t adaptor_id = 0x00;
ssize_t ret;
/*
* Let's see if the adaptor is there the by reading the
* HDMI ID registers.
*
* Note that type 1 DVI adaptors are not required to implemnt
* any registers, and that presents a problem for detection.
* If the i2c transfer is nacked, we may or may not be dealing
* with a type 1 DVI adaptor. Some other mechanism of detecting
* the presence of the adaptor is required. One way would be
* to check the state of the CONFIG1 pin, Another method would
* simply require the driver to know whether the port is a DP++
* port or a native HDMI port. Both of these methods are entirely
* hardware/driver specific so we can't deal with them here.
*/
ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_HDMI_ID,
hdmi_id, sizeof(hdmi_id));
if (ret)
return DRM_DP_DUAL_MODE_UNKNOWN;
/*
* Sigh. Some (maybe all?) type 1 adaptors are broken and ack
* the offset but ignore it, and instead they just always return
* data from the start of the HDMI ID buffer. So for a broken
* type 1 HDMI adaptor a single byte read will always give us
* 0x44, and for a type 1 DVI adaptor it should give 0x00
* (assuming it implements any registers). Fortunately neither
* of those values will match the type 2 signature of the
* DP_DUAL_MODE_ADAPTOR_ID register so we can proceed with
* the type 2 adaptor detection safely even in the presence
* of broken type 1 adaptors.
*/
ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
&adaptor_id, sizeof(adaptor_id));
if (ret == 0) {
if (is_type2_adaptor(adaptor_id)) {
if (is_hdmi_adaptor(hdmi_id))
return DRM_DP_DUAL_MODE_TYPE2_HDMI;
else
return DRM_DP_DUAL_MODE_TYPE2_DVI;
}
}
if (is_hdmi_adaptor(hdmi_id))
return DRM_DP_DUAL_MODE_TYPE1_HDMI;
else
return DRM_DP_DUAL_MODE_TYPE1_DVI;
}
EXPORT_SYMBOL(drm_dp_dual_mode_detect);
/**
* drm_dp_dual_mode_max_tmds_clock - Max TMDS clock for DP dual mode adaptor
* @type: DP dual mode adaptor type
* @adapter: I2C adapter for the DDC bus
*
* Determine the max TMDS clock the adaptor supports based on the
* type of the dual mode adaptor and the DP_DUAL_MODE_MAX_TMDS_CLOCK
* register (on type2 adaptors). As some type 1 adaptors have
* problems with registers (see comments in drm_dp_dual_mode_detect())
* we don't read the register on those, instead we simply assume
* a 165 MHz limit based on the specification.
*
* Returns:
* Maximum supported TMDS clock rate for the DP dual mode adaptor in kHz.
*/
int drm_dp_dual_mode_max_tmds_clock(enum drm_dp_dual_mode_type type,
struct i2c_adapter *adapter)
{
uint8_t max_tmds_clock;
ssize_t ret;
/* native HDMI so no limit */
if (type == DRM_DP_DUAL_MODE_NONE)
return 0;
/*
* Type 1 adaptors are limited to 165MHz
* Type 2 adaptors can tells us their limit
*/
if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
return 165000;
ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_MAX_TMDS_CLOCK,
&max_tmds_clock, sizeof(max_tmds_clock));
if (ret || max_tmds_clock == 0x00 || max_tmds_clock == 0xff) {
DRM_DEBUG_KMS("Failed to query max TMDS clock\n");
return 165000;
}
return max_tmds_clock * 5000 / 2;
}
EXPORT_SYMBOL(drm_dp_dual_mode_max_tmds_clock);
/**
* drm_dp_dual_mode_get_tmds_output - Get the state of the TMDS output buffers in the DP dual mode adaptor
* @type: DP dual mode adaptor type
* @adapter: I2C adapter for the DDC bus
* @enabled: current state of the TMDS output buffers
*
* Get the state of the TMDS output buffers in the adaptor. For
* type2 adaptors this is queried from the DP_DUAL_MODE_TMDS_OEN
* register. As some type 1 adaptors have problems with registers
* (see comments in drm_dp_dual_mode_detect()) we don't read the
* register on those, instead we simply assume that the buffers
* are always enabled.
*
* Returns:
* 0 on success, negative error code on failure
*/
int drm_dp_dual_mode_get_tmds_output(enum drm_dp_dual_mode_type type,
struct i2c_adapter *adapter,
bool *enabled)
{
uint8_t tmds_oen;
ssize_t ret;
if (type < DRM_DP_DUAL_MODE_TYPE2_DVI) {
*enabled = true;
return 0;
}
ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
&tmds_oen, sizeof(tmds_oen));
if (ret) {
DRM_DEBUG_KMS("Failed to query state of TMDS output buffers\n");
return ret;
}
*enabled = !(tmds_oen & DP_DUAL_MODE_TMDS_DISABLE);
return 0;
}
EXPORT_SYMBOL(drm_dp_dual_mode_get_tmds_output);
/**
* drm_dp_dual_mode_set_tmds_output - Enable/disable TMDS output buffers in the DP dual mode adaptor
* @type: DP dual mode adaptor type
* @adapter: I2C adapter for the DDC bus
* @enable: enable (as opposed to disable) the TMDS output buffers
*
* Set the state of the TMDS output buffers in the adaptor. For
* type2 this is set via the DP_DUAL_MODE_TMDS_OEN register. As
* some type 1 adaptors have problems with registers (see comments
* in drm_dp_dual_mode_detect()) we avoid touching the register,
* making this function a no-op on type 1 adaptors.
*
* Returns:
* 0 on success, negative error code on failure
*/
int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
struct i2c_adapter *adapter, bool enable)
{
uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
ssize_t ret;
if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
return 0;
ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
&tmds_oen, sizeof(tmds_oen));
if (ret) {
DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n",
enable ? "enable" : "disable");
return ret;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
/**
* drm_dp_get_dual_mode_type_name - Get the name of the DP dual mode adaptor type as a string
* @type: DP dual mode adaptor type
*
* Returns:
* String representation of the DP dual mode adaptor type
*/
const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
{
switch (type) {
case DRM_DP_DUAL_MODE_NONE:
return "none";
case DRM_DP_DUAL_MODE_TYPE1_DVI:
return "type 1 DVI";
case DRM_DP_DUAL_MODE_TYPE1_HDMI:
return "type 1 HDMI";
case DRM_DP_DUAL_MODE_TYPE2_DVI:
return "type 2 DVI";
case DRM_DP_DUAL_MODE_TYPE2_HDMI:
return "type 2 HDMI";
default:
WARN_ON(type != DRM_DP_DUAL_MODE_UNKNOWN);
return "unknown";
}
}
EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);