1 files changed, 366 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
new file mode 100644
index 000000000000..a7b2a751f6fe
--- /dev/null
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -0,0 +1,366 @@
+/*
+ * 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, &offset, 1);
+	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);