Commit 9e736cd4 authored by Baihan Li's avatar Baihan Li Committed by Dmitry Baryshkov
Browse files

drm/hisilicon/hibmc: Add dp serdes cfg to adjust serdes rate, voltage and pre-emphasis 



This dp controller need features of digital-to-analog conversion and
high-speed transmission in chip by its extern serdes controller. Our
serdes cfg is relatively simple, just need two register configurations.
Don't need too much functions, like: power on/off, initialize, and some
complex configurations, so I'm not going to use the phy framework.
This serdes is inited and configured in dp initialization, and also
integrating them into link training process.

For rate changing, we can change from 1.62-8.2Gpbs by cfg reg.
For voltage and pre-emphasis levels changing, we can cfg different
serdes ffe value.

Signed-off-by: default avatarBaihan Li <libaihan@huawei.com>
Signed-off-by: default avatarYongbang Shi <shiyongbang@huawei.com>
Reviewed-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20250331074212.3370287-3-shiyongbang@huawei.com


Signed-off-by: default avatarDmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
parent f9698f80

drivers/gpu/drm/hisilicon/hibmc/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only

hibmc-drm-y := hibmc_drm_drv.o hibmc_drm_de.o hibmc_drm_vdac.o hibmc_drm_i2c.o \

	       dp/dp_aux.o dp/dp_link.o dp/dp_hw.o hibmc_drm_dp.o

	       dp/dp_aux.o dp/dp_link.o dp/dp_hw.o dp/dp_serdes.o hibmc_drm_dp.o



obj-$(CONFIG_DRM_HISI_HIBMC) += hibmc-drm.o

drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h

+4 −0
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@@ -38,6 +38,7 @@ struct hibmc_dp_dev { 
	struct mutex lock; /* protects concurrent RW in hibmc_dp_reg_write_field() */

	struct hibmc_dp_link link;

	u8 dpcd[DP_RECEIVER_CAP_SIZE];

	void __iomem *serdes_base;

};



#define dp_field_modify(reg_value, mask, val)				\
@@ -59,5 +60,8 @@ struct hibmc_dp_dev { 


void hibmc_dp_aux_init(struct hibmc_dp_dev *dp);

int hibmc_dp_link_training(struct hibmc_dp_dev *dp);

int hibmc_dp_serdes_init(struct hibmc_dp_dev *dp);

int hibmc_dp_serdes_rate_switch(u8 rate, struct hibmc_dp_dev *dp);

int hibmc_dp_serdes_set_tx_cfg(struct hibmc_dp_dev *dp, u8 train_set[HIBMC_DP_LANE_NUM_MAX]);



#endif

drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c

+5 −0
Original line number Diff line number Diff line
@@ -151,6 +151,7 @@ int hibmc_dp_hw_init(struct hibmc_dp *dp) 
{

	struct drm_device *drm_dev = dp->drm_dev;

	struct hibmc_dp_dev *dp_dev;

	int ret;



	dp_dev = devm_kzalloc(drm_dev->dev, sizeof(struct hibmc_dp_dev), GFP_KERNEL);

	if (!dp_dev)
@@ -165,6 +166,10 @@ int hibmc_dp_hw_init(struct hibmc_dp *dp) 


	hibmc_dp_aux_init(dp_dev);



	ret = hibmc_dp_serdes_init(dp_dev);

	if (ret)

		return ret;



	dp_dev->link.cap.lanes = 0x2;

	dp_dev->link.cap.link_rate = DP_LINK_BW_2_7;

drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h

+23 −0
Original line number Diff line number Diff line
@@ -95,4 +95,27 @@ 


#define HIBMC_DP_TIMING_SYNC_CTRL		0xFF0



/* dp serdes reg */

#define HIBMC_DP_HOST_OFFSET		0x10000

#define HIBMC_DP_LANE0_RATE_OFFSET	0x4

#define HIBMC_DP_LANE1_RATE_OFFSET	0xc

#define HIBMC_DP_LANE_STATUS_OFFSET	0x10

#define HIBMC_DP_PMA_LANE0_OFFSET	0x18

#define HIBMC_DP_PMA_LANE1_OFFSET	0x1c

#define HIBMC_DP_PMA_TXDEEMPH		GENMASK(18, 1)

#define DP_SERDES_DONE			0x3



/* dp serdes TX-Deempth Configuration */

#define DP_SERDES_VOL0_PRE0		0x280

#define DP_SERDES_VOL0_PRE1		0x2300

#define DP_SERDES_VOL0_PRE2		0x53c0

#define DP_SERDES_VOL0_PRE3		0x8400

#define DP_SERDES_VOL1_PRE0		0x380

#define DP_SERDES_VOL1_PRE1		0x3440

#define DP_SERDES_VOL1_PRE2		0x6480

#define DP_SERDES_VOL2_PRE0		0x4c1

#define DP_SERDES_VOL2_PRE1		0x4500

#define DP_SERDES_VOL3_PRE0		0x600

#define DP_SERDES_BW_8_1		0x3



#endif

drivers/gpu/drm/hisilicon/hibmc/dp/dp_serdes.c

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+71 −0
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// SPDX-License-Identifier: GPL-2.0-or-later

// Copyright (c) 2025 Hisilicon Limited.



#include <linux/delay.h>

#include <drm/drm_device.h>

#include <drm/drm_print.h>

#include "dp_comm.h"

#include "dp_config.h"

#include "dp_reg.h"



int hibmc_dp_serdes_set_tx_cfg(struct hibmc_dp_dev *dp, u8 train_set[HIBMC_DP_LANE_NUM_MAX])

{

	static const u32 serdes_tx_cfg[4][4] = { {DP_SERDES_VOL0_PRE0, DP_SERDES_VOL0_PRE1,

						  DP_SERDES_VOL0_PRE2, DP_SERDES_VOL0_PRE3},

						 {DP_SERDES_VOL1_PRE0, DP_SERDES_VOL1_PRE1,

						  DP_SERDES_VOL1_PRE2}, {DP_SERDES_VOL2_PRE0,

						  DP_SERDES_VOL2_PRE1}, {DP_SERDES_VOL3_PRE0}};

	int cfg[2];

	int i;



	for (i = 0; i < HIBMC_DP_LANE_NUM_MAX; i++) {

		cfg[i] = serdes_tx_cfg[FIELD_GET(DP_TRAIN_VOLTAGE_SWING_MASK, train_set[i])]

				      [FIELD_GET(DP_TRAIN_PRE_EMPHASIS_MASK, train_set[i])];

		if (!cfg[i])

			return -EINVAL;



		/* lane1 offset is 4 */

		writel(FIELD_PREP(HIBMC_DP_PMA_TXDEEMPH, cfg[i]),

		       dp->serdes_base + HIBMC_DP_PMA_LANE0_OFFSET + i * 4);

	}



	usleep_range(300, 500);



	if (readl(dp->serdes_base + HIBMC_DP_LANE_STATUS_OFFSET) != DP_SERDES_DONE) {

		drm_dbg_dp(dp->dev, "dp serdes cfg failed\n");

		return -EAGAIN;

	}



	return 0;

}



int hibmc_dp_serdes_rate_switch(u8 rate, struct hibmc_dp_dev *dp)

{

	writel(rate, dp->serdes_base + HIBMC_DP_LANE0_RATE_OFFSET);

	writel(rate, dp->serdes_base + HIBMC_DP_LANE1_RATE_OFFSET);



	usleep_range(300, 500);



	if (readl(dp->serdes_base + HIBMC_DP_LANE_STATUS_OFFSET) != DP_SERDES_DONE) {

		drm_dbg_dp(dp->dev, "dp serdes rate switching failed\n");

		return -EAGAIN;

	}



	if (rate < DP_SERDES_BW_8_1)

		drm_dbg_dp(dp->dev, "reducing serdes rate to :%d\n",

			   rate ? rate * HIBMC_DP_LINK_RATE_CAL * 10 : 162);



	return 0;

}



int hibmc_dp_serdes_init(struct hibmc_dp_dev *dp)

{

	dp->serdes_base = dp->base + HIBMC_DP_HOST_OFFSET;



	writel(FIELD_PREP(HIBMC_DP_PMA_TXDEEMPH, DP_SERDES_VOL0_PRE0),

	       dp->serdes_base + HIBMC_DP_PMA_LANE0_OFFSET);

	writel(FIELD_PREP(HIBMC_DP_PMA_TXDEEMPH, DP_SERDES_VOL0_PRE0),

	       dp->serdes_base + HIBMC_DP_PMA_LANE1_OFFSET);



	return hibmc_dp_serdes_rate_switch(DP_SERDES_BW_8_1, dp);

}