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From: Svyatoslav Ryhel <clamor95@gmail.com>
To: Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <rfoss@kernel.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>,
	Simona Vetter <simona@ffwll.ch>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Svyatoslav Ryhel <clamor95@gmail.com>
Cc: dri-devel@lists.freedesktop.org,
	devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 2/2] drm: bridge: Add support for Solomon SSD2825 RGB/DSI
 bridge
Date: Sun, 23 Feb 2025 17:32:44 +0200
Message-ID: <20250223153244.149102-3-clamor95@gmail.com>
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SSD2825 is a cost-effective MIPI Bridge Chip solution targeting mainly
smartphones. It can convert 24bit RGB interface into 4-lane MIPI-DSI
interface to drive display modules of up to 800 x 1366, while supporting
AMOLED, a-si LCD or LTPS panel technologies for smartphone applications.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 drivers/gpu/drm/bridge/Kconfig   |  13 +
 drivers/gpu/drm/bridge/Makefile  |   1 +
 drivers/gpu/drm/bridge/ssd2825.c | 821 +++++++++++++++++++++++++++++++
 3 files changed, 835 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/ssd2825.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 6b4664d91faa..8e915bab1cfd 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -306,6 +306,19 @@ config DRM_SIMPLE_BRIDGE
 	  Support for non-programmable DRM bridges, such as ADI ADV7123, TI
 	  THS8134 and THS8135 or passive resistor ladder DACs.
=20
+config DRM_SOLOMON_SSD2825
+	tristate "SSD2825 RGB/DSI bridge"
+	depends on SPI_MASTER && OF
+	select DRM_MIPI_DSI
+	select DRM_KMS_HELPER
+	select DRM_PANEL
+	help
+	  Say Y here if you want support for the Solomon SSD2825 RGB/DSI
+	  SPI bridge driver.
+
+	  Say M here if you want to support this hardware as a module.
+	  The module will be named "solomon-ssd2825".
+
 config DRM_THINE_THC63LVD1024
 	tristate "Thine THC63LVD1024 LVDS decoder bridge"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makef=
ile
index 97304b429a53..c621ab3fa3a9 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_DRM_SIL_SII8620) +=3D sil-sii8620.o
 obj-$(CONFIG_DRM_SII902X) +=3D sii902x.o
 obj-$(CONFIG_DRM_SII9234) +=3D sii9234.o
 obj-$(CONFIG_DRM_SIMPLE_BRIDGE) +=3D simple-bridge.o
+obj-$(CONFIG_DRM_SOLOMON_SSD2825) +=3D ssd2825.o
 obj-$(CONFIG_DRM_THINE_THC63LVD1024) +=3D thc63lvd1024.o
 obj-$(CONFIG_DRM_TOSHIBA_TC358762) +=3D tc358762.o
 obj-$(CONFIG_DRM_TOSHIBA_TC358764) +=3D tc358764.o
diff --git a/drivers/gpu/drm/bridge/ssd2825.c b/drivers/gpu/drm/bridge/ssd2=
825.c
new file mode 100644
index 000000000000..102e24a1fb40
--- /dev/null
+++ b/drivers/gpu/drm/bridge/ssd2825.c
@@ -0,0 +1,821 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/units.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+#include <video/mipi_display.h>
+
+#define SSD2825_DEVICE_ID_REG			0xb0
+#define SSD2825_RGB_INTERFACE_CTRL_REG_1	0xb1
+#define SSD2825_RGB_INTERFACE_CTRL_REG_2	0xb2
+#define SSD2825_RGB_INTERFACE_CTRL_REG_3	0xb3
+#define SSD2825_RGB_INTERFACE_CTRL_REG_4	0xb4
+#define SSD2825_RGB_INTERFACE_CTRL_REG_5	0xb5
+#define SSD2825_RGB_INTERFACE_CTRL_REG_6	0xb6
+#define   SSD2825_NON_BURST_EV			BIT(2)
+#define   SSD2825_BURST				BIT(3)
+#define   SSD2825_PCKL_HIGH			BIT(13)
+#define   SSD2825_HSYNC_HIGH			BIT(14)
+#define   SSD2825_VSYNC_HIGH			BIT(15)
+#define SSD2825_CONFIGURATION_REG		0xb7
+#define   SSD2825_CONF_REG_HS			BIT(0)
+#define   SSD2825_CONF_REG_CKE			BIT(1)
+#define   SSD2825_CONF_REG_SLP			BIT(2)
+#define   SSD2825_CONF_REG_VEN			BIT(3)
+#define   SSD2825_CONF_REG_HCLK			BIT(4)
+#define   SSD2825_CONF_REG_CSS			BIT(5)
+#define   SSD2825_CONF_REG_DCS			BIT(6)
+#define   SSD2825_CONF_REG_REN			BIT(7)
+#define   SSD2825_CONF_REG_ECD			BIT(8)
+#define   SSD2825_CONF_REG_EOT			BIT(9)
+#define   SSD2825_CONF_REG_LPE			BIT(10)
+#define SSD2825_VC_CTRL_REG			0xb8
+#define SSD2825_PLL_CTRL_REG			0xb9
+#define SSD2825_PLL_CONFIGURATION_REG		0xba
+#define SSD2825_CLOCK_CTRL_REG			0xbb
+#define SSD2825_PACKET_SIZE_CTRL_REG_1		0xbc
+#define SSD2825_PACKET_SIZE_CTRL_REG_2		0xbd
+#define SSD2825_PACKET_SIZE_CTRL_REG_3		0xbe
+#define SSD2825_PACKET_DROP_REG			0xbf
+#define SSD2825_OPERATION_CTRL_REG		0xc0
+#define SSD2825_MAX_RETURN_SIZE_REG		0xc1
+#define SSD2825_RETURN_DATA_COUNT_REG		0xc2
+#define SSD2825_ACK_RESPONSE_REG		0xc3
+#define SSD2825_LINE_CTRL_REG			0xc4
+#define SSD2825_INTERRUPT_CTRL_REG		0xc5
+#define SSD2825_INTERRUPT_STATUS_REG		0xc6
+#define SSD2825_ERROR_STATUS_REG		0xc7
+#define SSD2825_DATA_FORMAT_REG			0xc8
+#define SSD2825_DELAY_ADJ_REG_1			0xc9
+#define SSD2825_DELAY_ADJ_REG_2			0xca
+#define SSD2825_DELAY_ADJ_REG_3			0xcb
+#define SSD2825_DELAY_ADJ_REG_4			0xcc
+#define SSD2825_DELAY_ADJ_REG_5			0xcd
+#define SSD2825_DELAY_ADJ_REG_6			0xce
+#define SSD2825_HS_TX_TIMER_REG_1		0xcf
+#define SSD2825_HS_TX_TIMER_REG_2		0xd0
+#define SSD2825_LP_RX_TIMER_REG_1		0xd1
+#define SSD2825_LP_RX_TIMER_REG_2		0xd2
+#define SSD2825_TE_STATUS_REG			0xd3
+#define SSD2825_SPI_READ_REG			0xd4
+#define   SSD2825_SPI_READ_REG_RESET		0xfa
+#define SSD2825_PLL_LOCK_REG			0xd5
+#define SSD2825_TEST_REG			0xd6
+#define SSD2825_TE_COUNT_REG			0xd7
+#define SSD2825_ANALOG_CTRL_REG_1		0xd8
+#define SSD2825_ANALOG_CTRL_REG_2		0xd9
+#define SSD2825_ANALOG_CTRL_REG_3		0xda
+#define SSD2825_ANALOG_CTRL_REG_4		0xdb
+#define SSD2825_INTERRUPT_OUT_CTRL_REG		0xdc
+#define SSD2825_RGB_INTERFACE_CTRL_REG_7	0xdd
+#define SSD2825_LANE_CONFIGURATION_REG		0xde
+#define SSD2825_DELAY_ADJ_REG_7			0xdf
+#define SSD2825_INPUT_PIN_CTRL_REG_1		0xe0
+#define SSD2825_INPUT_PIN_CTRL_REG_2		0xe1
+#define SSD2825_BIDIR_PIN_CTRL_REG_1		0xe2
+#define SSD2825_BIDIR_PIN_CTRL_REG_2		0xe3
+#define SSD2825_BIDIR_PIN_CTRL_REG_3		0xe4
+#define SSD2825_BIDIR_PIN_CTRL_REG_4		0xe5
+#define SSD2825_BIDIR_PIN_CTRL_REG_5		0xe6
+#define SSD2825_BIDIR_PIN_CTRL_REG_6		0xe7
+#define SSD2825_BIDIR_PIN_CTRL_REG_7		0xe8
+#define SSD2825_CABC_BRIGHTNESS_CTRL_REG_1	0xe9
+#define SSD2825_CABC_BRIGHTNESS_CTRL_REG_2	0xea
+#define SSD2825_CABC_BRIGHTNESS_STATUS_REG	0xeb
+#define SSD2825_READ_REG			0xff
+
+#define SSD2825_COM_BYTE			0x00
+#define SSD2825_DAT_BYTE			0x01
+
+#define	SSD2828_LP_CLOCK_DIVIDER(n)		(((n) - 1) & 0x3f)
+#define SSD2825_LP_MIN_CLK			5000 /* KHz */
+#define SSD2825_REF_MIN_CLK			2000 /* KHz */
+
+static const struct regulator_bulk_data ssd2825_supplies[] =3D {
+	{ .supply =3D "dvdd" },
+	{ .supply =3D "avdd" },
+	{ .supply =3D "vddio" },
+};
+
+struct ssd2825_dsi_output {
+	struct mipi_dsi_device *dev;
+	struct drm_panel *panel;
+	struct drm_bridge *bridge;
+};
+
+struct ssd2825_priv {
+	struct spi_device *spi;
+	struct device *dev;
+
+	struct gpio_desc *reset_gpio;
+	struct regulator_bulk_data *supplies;
+
+	struct clk *tx_clk;
+
+	int enabled;
+
+	struct mipi_dsi_host dsi_host;
+	struct drm_bridge bridge;
+	struct ssd2825_dsi_output output;
+
+	struct mutex mlock;	/* for host transfer operations */
+
+	u32 pd_lines;		/* number of Parallel Port Input Data Lines */
+	u32 dsi_lanes;		/* number of DSI Lanes */
+
+	/* Parameters for PLL programming */
+	u32 pll_freq_kbps;	/* PLL in kbps */
+	u32 nibble_freq_khz;	/* PLL div by 4 */
+
+	u32 hzd;		/* HS Zero Delay in ns*/
+	u32 hpd;		/* HS Prepare Delay is ns */
+};
+
+static inline struct ssd2825_priv *dsi_host_to_ssd2825(struct mipi_dsi_host
+							 *host)
+{
+	return container_of(host, struct ssd2825_priv, dsi_host);
+}
+
+static inline struct ssd2825_priv *bridge_to_ssd2825(struct drm_bridge
+						     *bridge)
+{
+	return container_of(bridge, struct ssd2825_priv, bridge);
+}
+
+static int ssd2825_write_raw(struct ssd2825_priv *priv, u8 high_byte, u8 l=
ow_byte)
+{
+	struct spi_device *spi =3D priv->spi;
+	u8 tx_buf[2];
+
+	/*
+	 * Low byte is the value, high byte defines type of
+	 * write cycle, 0 for command and 1 for data.
+	 */
+	tx_buf[0] =3D low_byte;
+	tx_buf[1] =3D high_byte;
+
+	return spi_write(spi, tx_buf, 2);
+}
+
+static int ssd2825_write_reg(struct ssd2825_priv *priv, u8 reg, u16 comman=
d)
+{
+	u8 datal =3D (command & 0x00FF);
+	u8 datah =3D (command & 0xFF00) >> 8;
+	int ret;
+
+	/* Command write cycle */
+	ret =3D ssd2825_write_raw(priv, SSD2825_COM_BYTE, reg);
+	if (ret)
+		return ret;
+
+	/* Data write cycle bits 7-0 */
+	ret =3D ssd2825_write_raw(priv, SSD2825_DAT_BYTE, datal);
+	if (ret)
+		return ret;
+
+	/* Data write cycle bits 15-8 */
+	ret =3D ssd2825_write_raw(priv, SSD2825_DAT_BYTE, datah);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ssd2825_write_dsi(struct ssd2825_priv *priv, const u8 *command,=
 int len)
+{
+	int ret, i;
+
+	ret =3D ssd2825_write_reg(priv, SSD2825_PACKET_SIZE_CTRL_REG_1, len);
+	if (ret)
+		return ret;
+
+	ret =3D ssd2825_write_raw(priv, SSD2825_COM_BYTE, SSD2825_PACKET_DROP_REG=
);
+	if (ret)
+		return ret;
+
+	for (i =3D 0; i < len; i++) {
+		ret =3D ssd2825_write_raw(priv, SSD2825_DAT_BYTE, command[i]);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int ssd2825_read_raw(struct ssd2825_priv *priv, u8 cmd, u16 *data)
+{
+	struct spi_device *spi =3D priv->spi;
+	struct spi_message msg;
+	struct spi_transfer xfer[2];
+	u8 tx_buf[2];
+	u8 rx_buf[2];
+	int ret;
+
+	memset(&xfer, 0, sizeof(xfer));
+
+	tx_buf[1] =3D (cmd & 0xFF00) >> 8;
+	tx_buf[0] =3D (cmd & 0x00FF);
+
+	xfer[0].tx_buf =3D tx_buf;
+	xfer[0].bits_per_word =3D 9;
+	xfer[0].len =3D 2;
+
+	xfer[1].rx_buf =3D rx_buf;
+	xfer[1].bits_per_word =3D 16;
+	xfer[1].len =3D 2;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer[0], &msg);
+	spi_message_add_tail(&xfer[1], &msg);
+
+	ret =3D spi_sync(spi, &msg);
+	if (ret)
+		dev_err(&spi->dev, "spi_sync_read failed %d\n", ret);
+
+	*data =3D rx_buf[1] | (rx_buf[0] << 8);
+
+	return 0;
+}
+
+static int ssd2825_read_reg(struct ssd2825_priv *priv, u8 reg, u16 *data)
+{
+	int ret;
+
+	/* Reset the read register */
+	ret =3D ssd2825_write_reg(priv, SSD2825_SPI_READ_REG, SSD2825_SPI_READ_RE=
G_RESET);
+	if (ret)
+		return ret;
+
+	/* Push the address to read */
+	ret =3D ssd2825_write_raw(priv, SSD2825_COM_BYTE, reg);
+	if (ret)
+		return ret;
+
+	/* Perform a reading cycle */
+	ret =3D ssd2825_read_raw(priv, SSD2825_SPI_READ_REG_RESET, data);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ssd2825_dsi_host_attach(struct mipi_dsi_host *host,
+				   struct mipi_dsi_device *dev)
+{
+	struct ssd2825_priv *priv =3D dsi_host_to_ssd2825(host);
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	struct device_node *ep;
+	int ret;
+
+	if (dev->lanes > 4) {
+		dev_err(priv->dev, "unsupported number of data lanes(%u)\n",
+			dev->lanes);
+		return -EINVAL;
+	}
+
+	/*
+	 * ssd2825 supports both Video and Pulse mode, but the driver only
+	 * implements Video (event) mode currently
+	 */
+	if (!(dev->mode_flags & MIPI_DSI_MODE_VIDEO)) {
+		dev_err(priv->dev, "Only MIPI_DSI_MODE_VIDEO is supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	ret =3D drm_of_find_panel_or_bridge(host->dev->of_node, 1, 0, &panel,
+					  &bridge);
+	if (ret)
+		return ret;
+
+	if (panel) {
+		bridge =3D drm_panel_bridge_add_typed(panel,
+						    DRM_MODE_CONNECTOR_DSI);
+		if (IS_ERR(bridge))
+			return PTR_ERR(bridge);
+	}
+
+	priv->output.dev =3D dev;
+	priv->output.bridge =3D bridge;
+	priv->output.panel =3D panel;
+
+	priv->dsi_lanes =3D dev->lanes;
+
+	/* get input ep (port0/endpoint0) */
+	ret =3D -EINVAL;
+	ep =3D of_graph_get_endpoint_by_regs(host->dev->of_node, 0, 0);
+	if (ep) {
+		ret =3D of_property_read_u32(ep, "bus-width", &priv->pd_lines);
+
+		of_node_put(ep);
+	}
+
+	if (ret)
+		priv->pd_lines =3D mipi_dsi_pixel_format_to_bpp(dev->format);
+
+	drm_bridge_add(&priv->bridge);
+
+	return 0;
+}
+
+static int ssd2825_dsi_host_detach(struct mipi_dsi_host *host,
+				   struct mipi_dsi_device *dev)
+{
+	struct ssd2825_priv *priv =3D dsi_host_to_ssd2825(host);
+
+	drm_bridge_remove(&priv->bridge);
+	if (priv->output.panel)
+		drm_panel_bridge_remove(priv->output.bridge);
+
+	return 0;
+}
+
+static ssize_t ssd2825_dsi_host_transfer(struct mipi_dsi_host *host,
+					 const struct mipi_dsi_msg *msg)
+{
+	struct ssd2825_priv *priv =3D dsi_host_to_ssd2825(host);
+	struct mipi_dsi_device *dsi_dev =3D priv->output.dev;
+	u8 buf =3D *(u8 *)msg->tx_buf;
+	u16 config;
+	int ret;
+
+	if (!priv->enabled) {
+		dev_err(priv->dev, "Bridge is not enabled\n");
+		return -ENODEV;
+	}
+
+	if (msg->rx_len) {
+		dev_warn(priv->dev, "MIPI rx is not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	guard(mutex)(&priv->mlock);
+
+	ret =3D ssd2825_read_reg(priv, SSD2825_CONFIGURATION_REG, &config);
+	if (ret)
+		return ret;
+
+	switch (msg->type) {
+	case MIPI_DSI_DCS_SHORT_WRITE:
+	case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
+	case MIPI_DSI_DCS_LONG_WRITE:
+		config |=3D SSD2825_CONF_REG_DCS;
+		break;
+	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
+	case MIPI_DSI_GENERIC_LONG_WRITE:
+		config &=3D ~SSD2825_CONF_REG_DCS;
+		break;
+	case MIPI_DSI_DCS_READ:
+	case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
+	default:
+		return 0;
+	}
+
+	ret =3D ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG, config);
+	if (ret)
+		return ret;
+
+	ret =3D ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0x0000);
+	if (ret)
+		return ret;
+
+	ret =3D ssd2825_write_dsi(priv, msg->tx_buf, msg->tx_len);
+	if (ret)
+		return ret;
+
+	if (buf =3D=3D MIPI_DCS_SET_DISPLAY_ON) {
+		/*
+		 * NOTE! This is here since it cannot be called in bridge enable because
+		 * bridge pre enable and bridge enable have no gap in between.
+		 *
+		 * Existing framework bridge-panel seq is:
+		 *	panel_prepare > bridge_pre_enable > bridge_enable > panel_enable
+		 *
+		 * Using prepare_prev_first was tested, but it switches seq like this:
+		 *	bridge_pre_enable > panel_prepare > bridge_enable > panel_enable
+		 *
+		 * This will not work since panel hw MUST be prepared before bridge is
+		 * configured. Correct seq should be:
+		 *	panel_prepare > bridge_pre_enable > panel_enable > bridge_enable
+		 *
+		 * Last two functions are swapped related to existing framework. I am not
+		 * aware about method which allows that.
+		 *
+		 * Once there will be such method/flag, code below should be moved into
+		 * bridge_enable since it is basically a bridge configuration completing
+		 * after initial panel DSI sequence is completed.
+		 */
+		config =3D SSD2825_CONF_REG_HS | SSD2825_CONF_REG_DCS |
+			 SSD2825_CONF_REG_ECD | SSD2825_CONF_REG_EOT;
+
+		if (dsi_dev->mode_flags & MIPI_DSI_MODE_VIDEO)
+			config |=3D SSD2825_CONF_REG_VEN;
+
+		if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
+			config &=3D ~SSD2825_CONF_REG_EOT;
+
+		/* Complete configuration after DSI commands were sent */
+		ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG, config);
+		ssd2825_write_reg(priv, SSD2825_PLL_CTRL_REG, 0x0001);
+		ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0x0000);
+	}
+
+	return 0;
+}
+
+static const struct mipi_dsi_host_ops ssd2825_dsi_host_ops =3D {
+	.attach =3D ssd2825_dsi_host_attach,
+	.detach =3D ssd2825_dsi_host_detach,
+	.transfer =3D ssd2825_dsi_host_transfer,
+};
+
+static void ssd2825_hw_reset(struct ssd2825_priv *priv)
+{
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(priv->reset_gpio, 0);
+	usleep_range(5000, 6000);
+}
+
+/*
+ * PLL configuration register settings.
+ *
+ * See the "PLL Configuration Register Description" in the SSD2825 datashe=
et.
+ */
+static u16 construct_pll_config(struct ssd2825_priv *priv,
+				u32 desired_pll_freq_kbps, u32 reference_freq_khz)
+{
+	u32 div_factor =3D 1, mul_factor, fr =3D 0;
+
+	while (reference_freq_khz / (div_factor + 1) >=3D SSD2825_REF_MIN_CLK)
+		div_factor++;
+	if (div_factor > 31)
+		div_factor =3D 31;
+
+	mul_factor =3D DIV_ROUND_UP(desired_pll_freq_kbps * div_factor,
+				  reference_freq_khz);
+
+	priv->pll_freq_kbps =3D reference_freq_khz * mul_factor / div_factor;
+	priv->nibble_freq_khz =3D priv->pll_freq_kbps / 4;
+
+	if (priv->pll_freq_kbps >=3D 501000)
+		fr =3D 3;
+	else if (priv->pll_freq_kbps >=3D 251000)
+		fr =3D 2;
+	else if (priv->pll_freq_kbps >=3D 126000)
+		fr =3D 1;
+
+	return (fr << 14) | (div_factor << 8) | mul_factor;
+}
+
+static int ssd2825_setup_pll(struct ssd2825_priv *priv,
+			     const struct drm_display_mode *mode)
+{
+	u16 pll_config, lp_div;
+	u32 nibble_delay, pclk_mult, tx_freq_khz;
+	u8 hzd, hpd;
+
+	tx_freq_khz =3D clk_get_rate(priv->tx_clk) / KILO;
+	if (!tx_freq_khz)
+		tx_freq_khz =3D SSD2825_REF_MIN_CLK;
+
+	pclk_mult =3D priv->pd_lines / priv->dsi_lanes + 1;
+	pll_config =3D construct_pll_config(priv, pclk_mult * mode->clock,
+					  tx_freq_khz);
+
+	lp_div =3D priv->pll_freq_kbps / (SSD2825_LP_MIN_CLK * 8);
+
+	/* nibble_delay in nanoseconds */
+	nibble_delay =3D MICRO / priv->nibble_freq_khz;
+
+	hzd =3D priv->hzd / nibble_delay;
+	hpd =3D (priv->hpd - 4 * nibble_delay) / nibble_delay;
+
+	/* Disable PLL */
+	ssd2825_write_reg(priv, SSD2825_PLL_CTRL_REG, 0x0000);
+	ssd2825_write_reg(priv, SSD2825_LINE_CTRL_REG, 0x0001);
+
+	/* Set delays */
+	ssd2825_write_reg(priv, SSD2825_DELAY_ADJ_REG_1, (hzd << 8) | hpd);
+
+	/* Set PLL coeficients */
+	ssd2825_write_reg(priv, SSD2825_PLL_CONFIGURATION_REG, pll_config);
+
+	/* Clock Control Register */
+	ssd2825_write_reg(priv, SSD2825_CLOCK_CTRL_REG,
+			  SSD2828_LP_CLOCK_DIVIDER(lp_div));
+
+	/* Enable PLL */
+	ssd2825_write_reg(priv, SSD2825_PLL_CTRL_REG, 0x0001);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0);
+
+	return 0;
+}
+
+static void ssd2825_bridge_atomic_pre_enable(struct drm_bridge *bridge,
+					     struct drm_bridge_state *old_bridge_state)
+{
+	struct ssd2825_priv *priv =3D bridge_to_ssd2825(bridge);
+	struct mipi_dsi_device *dsi_dev =3D priv->output.dev;
+	struct drm_atomic_state *state =3D old_bridge_state->base.state;
+	const struct drm_crtc_state *crtc_state;
+	const struct drm_display_mode *mode;
+	struct drm_connector *connector;
+	struct drm_crtc *crtc;
+	u32 input_bus_flags =3D bridge->timings->input_bus_flags;
+	u16 flags =3D 0, config;
+	u8 pixel_format;
+	int ret;
+
+	if (priv->enabled)
+		return;
+
+	/* Power Sequence */
+	ret =3D clk_prepare_enable(priv->tx_clk);
+	if (ret)
+		dev_err(priv->dev, "error enabling tx_clk (%d)\n", ret);
+
+	ret =3D regulator_bulk_enable(ARRAY_SIZE(ssd2825_supplies), priv->supplie=
s);
+	if (ret)
+		dev_err(priv->dev, "error enabling regulators (%d)\n", ret);
+
+	usleep_range(1000, 2000);
+
+	ssd2825_hw_reset(priv);
+
+	/* Perform SW reset */
+	ssd2825_write_reg(priv, SSD2825_OPERATION_CTRL_REG, 0x0100);
+
+	/* Set pixel format */
+	switch (dsi_dev->format) {
+	case MIPI_DSI_FMT_RGB565:
+		pixel_format =3D 0x00;
+		break;
+	case MIPI_DSI_FMT_RGB666_PACKED:
+		pixel_format =3D 0x01;
+		break;
+	case MIPI_DSI_FMT_RGB666:
+		pixel_format =3D 0x02;
+		break;
+	case MIPI_DSI_FMT_RGB888:
+	default:
+		pixel_format =3D 0x03;
+		break;
+	}
+
+	connector =3D drm_atomic_get_new_connector_for_encoder(state,
+							     bridge->encoder);
+	crtc =3D drm_atomic_get_new_connector_state(state, connector)->crtc;
+	crtc_state =3D drm_atomic_get_new_crtc_state(state, crtc);
+	mode =3D &crtc_state->adjusted_mode;
+
+	/* Set panel timings */
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_1,
+			  ((mode->vtotal - mode->vsync_end) << 8) |
+			  (mode->htotal - mode->hsync_end));
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_2,
+			  ((mode->vtotal - mode->vsync_start) << 8) |
+			  (mode->htotal - mode->hsync_start));
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_3,
+			  ((mode->vsync_start - mode->vdisplay) << 8) |
+			  (mode->hsync_start - mode->hdisplay));
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_4, mode->hdisplay);
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_5, mode->vdisplay);
+
+	if (mode->flags & DRM_MODE_FLAG_PHSYNC)
+		flags |=3D SSD2825_HSYNC_HIGH;
+
+	if (mode->flags & DRM_MODE_FLAG_PVSYNC)
+		flags |=3D SSD2825_VSYNC_HIGH;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_VIDEO)
+		flags |=3D SSD2825_NON_BURST_EV;
+
+	if (input_bus_flags & DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE)
+		flags |=3D SSD2825_PCKL_HIGH;
+
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_6, flags | pixel_f=
ormat);
+	ssd2825_write_reg(priv, SSD2825_LANE_CONFIGURATION_REG, dsi_dev->lanes - =
1);
+	ssd2825_write_reg(priv, SSD2825_TEST_REG, 0x0004);
+
+	/* Call PLL configuration */
+	ssd2825_setup_pll(priv, mode);
+
+	usleep_range(10000, 11000);
+
+	config =3D SSD2825_CONF_REG_HS | SSD2825_CONF_REG_CKE | SSD2825_CONF_REG_=
DCS |
+		 SSD2825_CONF_REG_ECD | SSD2825_CONF_REG_EOT;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_LPM)
+		config &=3D ~SSD2825_CONF_REG_HS;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
+		config &=3D ~SSD2825_CONF_REG_EOT;
+
+	/* Initial DSI configuration register set */
+	ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG, config);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0);
+
+	priv->enabled =3D true;
+}
+
+static void ssd2825_bridge_atomic_enable(struct drm_bridge *bridge,
+					 struct drm_bridge_state *old_bridge_state)
+{
+	/* placeholder */
+}
+
+static void ssd2825_bridge_atomic_disable(struct drm_bridge *bridge,
+					  struct drm_bridge_state *old_bridge_state)
+{
+	struct ssd2825_priv *priv =3D bridge_to_ssd2825(bridge);
+	int ret;
+
+	if (!priv->enabled)
+		return;
+
+	msleep(100);
+
+	/* Exit DSI configuration register set */
+	ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG,
+			  SSD2825_CONF_REG_ECD | SSD2825_CONF_REG_EOT);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0);
+
+	/* HW disable */
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	usleep_range(5000, 6000);
+
+	ret =3D regulator_bulk_disable(ARRAY_SIZE(ssd2825_supplies),
+				     priv->supplies);
+	if (ret < 0)
+		dev_err(priv->dev, "error disabling regulators (%d)\n", ret);
+
+	clk_disable_unprepare(priv->tx_clk);
+
+	priv->enabled =3D false;
+}
+
+static int ssd2825_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
+{
+	struct ssd2825_priv *priv =3D bridge_to_ssd2825(bridge);
+
+	return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge,
+				 flags);
+}
+
+static enum drm_mode_status
+ssd2825_bridge_mode_valid(struct drm_bridge *bridge,
+			  const struct drm_display_info *info,
+			  const struct drm_display_mode *mode)
+{
+	if (mode->hdisplay > 1366)
+		return MODE_H_ILLEGAL;
+
+	if (mode->vdisplay > 1366)
+		return MODE_V_ILLEGAL;
+
+	return MODE_OK;
+}
+
+static bool ssd2825_mode_fixup(struct drm_bridge *bridge,
+			       const struct drm_display_mode *mode,
+			       struct drm_display_mode *adjusted_mode)
+{
+	/* Default to positive sync */
+
+	if (!(adjusted_mode->flags &
+	      (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_NHSYNC)))
+		adjusted_mode->flags |=3D DRM_MODE_FLAG_PHSYNC;
+
+	if (!(adjusted_mode->flags &
+	      (DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_NVSYNC)))
+		adjusted_mode->flags |=3D DRM_MODE_FLAG_PVSYNC;
+
+	return true;
+}
+
+static const struct drm_bridge_funcs ssd2825_bridge_funcs =3D {
+	.attach =3D ssd2825_bridge_attach,
+	.mode_valid =3D ssd2825_bridge_mode_valid,
+	.mode_fixup =3D ssd2825_mode_fixup,
+
+	.atomic_pre_enable =3D ssd2825_bridge_atomic_pre_enable,
+	.atomic_enable =3D ssd2825_bridge_atomic_enable,
+	.atomic_disable =3D ssd2825_bridge_atomic_disable,
+
+	.atomic_reset =3D drm_atomic_helper_bridge_reset,
+	.atomic_duplicate_state =3D drm_atomic_helper_bridge_duplicate_state,
+	.atomic_destroy_state =3D drm_atomic_helper_bridge_destroy_state,
+};
+
+static const struct drm_bridge_timings default_ssd2825_timings =3D {
+	.input_bus_flags =3D DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
+		 | DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE
+		 | DRM_BUS_FLAG_DE_HIGH,
+};
+
+static int ssd2825_probe(struct spi_device *spi)
+{
+	struct ssd2825_priv *priv;
+	struct device *dev =3D &spi->dev;
+	struct device_node *np =3D dev->of_node;
+	int ret;
+
+	/* Driver supports only 8 bit 3 Wire mode */
+	spi->bits_per_word =3D 9;
+
+	ret =3D spi_setup(spi);
+	if (ret)
+		return ret;
+
+	priv =3D devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, priv);
+	priv->spi =3D spi;
+
+	dev_set_drvdata(dev, priv);
+	priv->dev =3D dev;
+
+	mutex_init(&priv->mlock);
+
+	priv->tx_clk =3D devm_clk_get_optional(dev, NULL);
+	if (IS_ERR(priv->tx_clk))
+		return dev_err_probe(dev, PTR_ERR(priv->tx_clk),
+				     "can't retrieve bridge tx_clk\n");
+
+	priv->reset_gpio =3D devm_gpiod_get_optional(dev, "reset",
+						   GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(priv->reset_gpio),
+				     "failed to get reset GPIO\n");
+
+	ret =3D devm_regulator_bulk_get_const(dev, ARRAY_SIZE(ssd2825_supplies),
+					    ssd2825_supplies, &priv->supplies);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get regulators\n");
+
+	priv->hzd =3D 133; /* ns */
+	device_property_read_u32(dev, "solomon,hs-zero-delay-ns", &priv->hzd);
+
+	priv->hpd =3D 40; /* ns */
+	device_property_read_u32(dev, "solomon,hs-prep-delay-ns", &priv->hpd);
+
+	priv->dsi_host.dev =3D dev;
+	priv->dsi_host.ops =3D &ssd2825_dsi_host_ops;
+
+	priv->bridge.funcs =3D &ssd2825_bridge_funcs;
+	priv->bridge.timings =3D &default_ssd2825_timings;
+	priv->bridge.of_node =3D np;
+
+	return mipi_dsi_host_register(&priv->dsi_host);
+}
+
+static void ssd2825_remove(struct spi_device *spi)
+{
+	struct ssd2825_priv *priv =3D spi_get_drvdata(spi);
+
+	mipi_dsi_host_unregister(&priv->dsi_host);
+}
+
+static const struct of_device_id ssd2825_of_match[] =3D {
+	{ .compatible =3D "solomon,ssd2825" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ssd2825_of_match);
+
+static struct spi_driver ssd2825_driver =3D {
+	.driver =3D {
+		.name =3D "ssd2825",
+		.of_match_table =3D ssd2825_of_match,
+	},
+	.probe =3D ssd2825_probe,
+	.remove =3D ssd2825_remove,
+};
+module_spi_driver(ssd2825_driver);
+
+MODULE_AUTHOR("Svyatoslav Ryhel <clamor95@gmail.com>");
+MODULE_DESCRIPTION("Solomon SSD2825 RGB to MIPI-DSI bridge driver SPI");
+MODULE_LICENSE("GPL");
--=20
2.43.0