drm/hisilicon/hibmc: add dp aux in hibmc drivers

Add dp aux read/write functions. They are basic functions
and will be used later.

Signed-off-by: Baihan Li <libaihan@huawei.com>
Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Tian Tao <tiantao6@hisilicon.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250103093824.1963816-2-shiyongbang@huawei.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/hisilicon/hibmc/Makefile

@@ -1,4 +1,5 @@
 # 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
+hibmc-drm-y := hibmc_drm_drv.o hibmc_drm_de.o hibmc_drm_vdac.o hibmc_drm_i2c.o \
+	       dp/dp_aux.o
 
 obj-$(CONFIG_DRM_HISI_HIBMC) += hibmc-drm.o

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

@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright (c) 2024 Hisilicon Limited.
+
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/minmax.h>
+#include <drm/drm_device.h>
+#include <drm/drm_print.h>
+#include "dp_comm.h"
+#include "dp_reg.h"
+
+#define HIBMC_AUX_CMD_REQ_LEN		GENMASK(7, 4)
+#define HIBMC_AUX_CMD_ADDR		GENMASK(27, 8)
+#define HIBMC_AUX_CMD_I2C_ADDR_ONLY	BIT(28)
+#define HIBMC_BYTES_IN_U32		4
+#define HIBMC_AUX_I2C_WRITE_SUCCESS	0x1
+#define HIBMC_DP_MIN_PULSE_NUM		0x9
+#define BITS_IN_U8			8
+
+static inline void hibmc_dp_aux_reset(struct hibmc_dp_dev *dp)
+{
+	hibmc_dp_reg_write_field(dp, HIBMC_DP_DPTX_RST_CTRL, HIBMC_DP_CFG_AUX_RST_N, 0x0);
+	usleep_range(10, 15);
+	hibmc_dp_reg_write_field(dp, HIBMC_DP_DPTX_RST_CTRL, HIBMC_DP_CFG_AUX_RST_N, 0x1);
+}
+
+static void hibmc_dp_aux_read_data(struct hibmc_dp_dev *dp, u8 *buf, u8 size)
+{
+	u32 reg_num;
+	u32 value;
+	u32 num;
+	u8 i, j;
+
+	reg_num = DIV_ROUND_UP(size, HIBMC_BYTES_IN_U32);
+	for (i = 0; i < reg_num; i++) {
+		/* number of bytes read from a single register */
+		num = min(size - i * HIBMC_BYTES_IN_U32, HIBMC_BYTES_IN_U32);
+		value = readl(dp->base + HIBMC_DP_AUX_RD_DATA0 + i * HIBMC_BYTES_IN_U32);
+		/* convert the 32-bit value of the register to the buffer. */
+		for (j = 0; j < num; j++)
+			buf[i * HIBMC_BYTES_IN_U32 + j] = value >> (j * BITS_IN_U8);
+	}
+}
+
+static void hibmc_dp_aux_write_data(struct hibmc_dp_dev *dp, u8 *buf, u8 size)
+{
+	u32 reg_num;
+	u32 value;
+	u32 num;
+	u8 i, j;
+
+	reg_num = DIV_ROUND_UP(size, HIBMC_BYTES_IN_U32);
+	for (i = 0; i < reg_num; i++) {
+		/* number of bytes written to a single register */
+		num = min_t(u8, size - i * HIBMC_BYTES_IN_U32, HIBMC_BYTES_IN_U32);
+		value = 0;
+		/* obtain the 32-bit value written to a single register. */
+		for (j = 0; j < num; j++)
+			value |= buf[i * HIBMC_BYTES_IN_U32 + j] << (j * BITS_IN_U8);
+		/* writing data to a single register */
+		writel(value, dp->base + HIBMC_DP_AUX_WR_DATA0 + i * HIBMC_BYTES_IN_U32);
+	}
+}
+
+static u32 hibmc_dp_aux_build_cmd(const struct drm_dp_aux_msg *msg)
+{
+	u32 aux_cmd = msg->request;
+
+	if (msg->size)
+		aux_cmd |= FIELD_PREP(HIBMC_AUX_CMD_REQ_LEN, (msg->size - 1));
+	else
+		aux_cmd |= FIELD_PREP(HIBMC_AUX_CMD_I2C_ADDR_ONLY, 1);
+
+	aux_cmd |= FIELD_PREP(HIBMC_AUX_CMD_ADDR, msg->address);
+
+	return aux_cmd;
+}
+
+/* ret >= 0, ret is size; ret < 0, ret is err code */
+static int hibmc_dp_aux_parse_xfer(struct hibmc_dp_dev *dp, struct drm_dp_aux_msg *msg)
+{
+	u32 buf_data_cnt;
+	u32 aux_status;
+
+	aux_status = readl(dp->base + HIBMC_DP_AUX_STATUS);
+	msg->reply = FIELD_GET(HIBMC_DP_CFG_AUX_STATUS, aux_status);
+
+	if (aux_status & HIBMC_DP_CFG_AUX_TIMEOUT)
+		return -ETIMEDOUT;
+
+	/* only address */
+	if (!msg->size)
+		return 0;
+
+	if (msg->reply != DP_AUX_NATIVE_REPLY_ACK)
+		return -EIO;
+
+	buf_data_cnt = FIELD_GET(HIBMC_DP_CFG_AUX_READY_DATA_BYTE, aux_status);
+
+	switch (msg->request) {
+	case DP_AUX_NATIVE_WRITE:
+		return msg->size;
+	case DP_AUX_I2C_WRITE | DP_AUX_I2C_MOT:
+		if (buf_data_cnt == HIBMC_AUX_I2C_WRITE_SUCCESS)
+			return msg->size;
+		else
+			return FIELD_GET(HIBMC_DP_CFG_AUX, aux_status);
+	case DP_AUX_NATIVE_READ:
+	case DP_AUX_I2C_READ | DP_AUX_I2C_MOT:
+		buf_data_cnt--;
+		if (buf_data_cnt != msg->size) {
+			/* only the successful part of data is read */
+			return -EBUSY;
+		}
+
+		/* all data is successfully read */
+		hibmc_dp_aux_read_data(dp, msg->buffer, msg->size);
+		return msg->size;
+	default:
+		return -EINVAL;
+	}
+}
+
+/* ret >= 0 ,ret is size; ret < 0, ret is err code */
+static ssize_t hibmc_dp_aux_xfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	struct hibmc_dp_dev *dp = container_of(aux, struct hibmc_dp_dev, aux);
+	u32 aux_cmd;
+	int ret;
+	u32 val; /* val will be assigned at the beginning of readl_poll_timeout function */
+
+	writel(0, dp->base + HIBMC_DP_AUX_WR_DATA0);
+	writel(0, dp->base + HIBMC_DP_AUX_WR_DATA1);
+	writel(0, dp->base + HIBMC_DP_AUX_WR_DATA2);
+	writel(0, dp->base + HIBMC_DP_AUX_WR_DATA3);
+
+	hibmc_dp_aux_write_data(dp, msg->buffer, msg->size);
+
+	aux_cmd = hibmc_dp_aux_build_cmd(msg);
+	writel(aux_cmd, dp->base + HIBMC_DP_AUX_CMD_ADDR);
+
+	/* enable aux transfer */
+	hibmc_dp_reg_write_field(dp, HIBMC_DP_AUX_REQ, HIBMC_DP_CFG_AUX_REQ, 0x1);
+	ret = readl_poll_timeout(dp->base + HIBMC_DP_AUX_REQ, val,
+				 !(val & HIBMC_DP_CFG_AUX_REQ), 50, 5000);
+	if (ret) {
+		hibmc_dp_aux_reset(dp);
+		return ret;
+	}
+
+	return hibmc_dp_aux_parse_xfer(dp, msg);
+}
+
+void hibmc_dp_aux_init(struct hibmc_dp_dev *dp)
+{
+	hibmc_dp_reg_write_field(dp, HIBMC_DP_AUX_REQ, HIBMC_DP_CFG_AUX_SYNC_LEN_SEL, 0x0);
+	hibmc_dp_reg_write_field(dp, HIBMC_DP_AUX_REQ, HIBMC_DP_CFG_AUX_TIMER_TIMEOUT, 0x1);
+	hibmc_dp_reg_write_field(dp, HIBMC_DP_AUX_REQ, HIBMC_DP_CFG_AUX_MIN_PULSE_NUM,
+				 HIBMC_DP_MIN_PULSE_NUM);
+
+	dp->aux.transfer = hibmc_dp_aux_xfer;
+	dp->aux.is_remote = 0;
+	drm_dp_aux_init(&dp->aux);
+}

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

@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (c) 2024 Hisilicon Limited. */
+
+#ifndef DP_COMM_H
+#define DP_COMM_H
+
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/kernel.h>
+#include <linux/bitfield.h>
+#include <linux/io.h>
+#include <drm/display/drm_dp_helper.h>
+
+struct hibmc_dp_dev {
+	struct drm_dp_aux aux;
+	struct drm_device *dev;
+	void __iomem *base;
+	struct mutex lock; /* protects concurrent RW in hibmc_dp_reg_write_field() */
+};
+
+#define dp_field_modify(reg_value, mask, val)				\
+	do {								\
+		(reg_value) &= ~(mask);					\
+		(reg_value) |= FIELD_PREP(mask, val);			\
+	} while (0)							\
+
+#define hibmc_dp_reg_write_field(dp, offset, mask, val)			\
+	do {								\
+		typeof(dp) _dp = dp;					\
+		typeof(_dp->base) addr = (_dp->base + (offset));	\
+		mutex_lock(&_dp->lock);					\
+		u32 reg_value = readl(addr);				\
+		dp_field_modify(reg_value, mask, val);			\
+		writel(reg_value, addr);				\
+		mutex_unlock(&_dp->lock);				\
+	} while (0)
+
+void hibmc_dp_aux_init(struct hibmc_dp_dev *dp);
+
+#endif

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

@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (c) 2024 Hisilicon Limited. */
+
+#ifndef DP_REG_H
+#define DP_REG_H
+
+#define HIBMC_DP_AUX_CMD_ADDR			0x50
+#define HIBMC_DP_AUX_WR_DATA0			0x54
+#define HIBMC_DP_AUX_WR_DATA1			0x58
+#define HIBMC_DP_AUX_WR_DATA2			0x5c
+#define HIBMC_DP_AUX_WR_DATA3			0x60
+#define HIBMC_DP_AUX_RD_DATA0			0x64
+#define HIBMC_DP_AUX_REQ			0x74
+#define HIBMC_DP_AUX_STATUS			0x78
+#define HIBMC_DP_DPTX_RST_CTRL			0x700
+
+#define HIBMC_DP_CFG_AUX_SYNC_LEN_SEL		BIT(1)
+#define HIBMC_DP_CFG_AUX_TIMER_TIMEOUT		BIT(2)
+#define HIBMC_DP_CFG_AUX_MIN_PULSE_NUM		GENMASK(13, 9)
+#define HIBMC_DP_CFG_AUX_REQ			BIT(0)
+#define HIBMC_DP_CFG_AUX_RST_N			BIT(4)
+#define HIBMC_DP_CFG_AUX_TIMEOUT		BIT(0)
+#define HIBMC_DP_CFG_AUX_READY_DATA_BYTE	GENMASK(16, 12)
+#define HIBMC_DP_CFG_AUX			GENMASK(24, 17)
+#define HIBMC_DP_CFG_AUX_STATUS			GENMASK(11, 4)
+
+#endif