[PATCH v8 2/4] drm/bridge: add lvds controller support for sam9x7

Dharma Balasubiramani
2024-04-21T01:12:00Z

Add a new LVDS controller driver for sam9x7 which does the following:
- Prepares and enables the LVDS Peripheral clock
- Defines its connector type as DRM_MODE_CONNECTOR_LVDS and adds itself
to the global bridge list.
- Identifies its output endpoint as panel and adds it to the encoder
display pipeline
- Enables the LVDS serializer

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
Acked-by: Hari Prasath Gujulan Elango <hari.prasathge@microchip.com>
---
Changelog
v7 -> v8
- Assign ret variable properly before checking it for err.
v6 -> v7
- Remove setting encoder type from bridge driver.
- Drop clk_disable() from pm_runtime_get_sync() error handling.
- Use devm_clk_get() instead of prepared version.
- Hence use clk_prepare_enable() and clk_disable_unprepare().
- Use devm_drm_of_get_bridge() instead of devm_drm_panel_bridge_add().
- Add error check for devm_pm_runtime_enable().
- Use dev_err() instead of DRM_DEV_ERROR() as it is deprecated.
- Add missing Acked-by tag.
v5 -> v6
- No Changes.
v4 -> v5
- Drop the unused variable 'format'.
- Use DRM wrapper for dev_err() to maintain uniformity.
- return -ENODEV instead of -EINVAL to maintain consistency with other DRM
bridge drivers.
v3 -> v4
- No changes.
v2 ->v3
- Correct Typo error "serializer".
- Consolidate get() and prepare() functions and use devm_clk_get_prepared().
- Remove unused variable 'ret' in probe().
- Use devm_pm_runtime_enable() and drop the mchp_lvds_remove().
v1 -> v2
- Drop 'res' variable and combine two lines into one.
- Handle deferred probe properly, use dev_err_probe().
- Don't print anything on deferred probe. Dropped print.
- Remove the MODULE_ALIAS and add MODULE_DEVICE_TABLE().
- symbol 'mchp_lvds_driver' was not declared. It should be static.
---
drivers/gpu/drm/bridge/Kconfig | 7 +
drivers/gpu/drm/bridge/Makefile | 1 +
drivers/gpu/drm/bridge/microchip-lvds.c | 229 ++++++++++++++++++++++++
3 files changed, 237 insertions(+)
create mode 100644 drivers/gpu/drm/bridge/microchip-lvds.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index efd996f6c138..889098e2d65f 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -190,6 +190,13 @@ config DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW
to DP++. This is used with the i.MX6 imx-ldb
driver. You are likely to say N here.

+config DRM_MICROCHIP_LVDS_SERIALIZER
+ tristate "Microchip LVDS serializer support"
+ depends on OF
+ depends on DRM_ATMEL_HLCDC
+ help
+ Support for Microchip's LVDS serializer.
+
config DRM_NWL_MIPI_DSI
tristate "Northwest Logic MIPI DSI Host controller"
depends on DRM
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 017b5832733b..7df87b582dca 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
+obj-$(CONFIG_DRM_MICROCHIP_LVDS_SERIALIZER) += microchip-lvds.o
obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
obj-$(CONFIG_DRM_PARADE_PS8640) += parade-ps8640.o
diff --git a/drivers/gpu/drm/bridge/microchip-lvds.c b/drivers/gpu/drm/bridge/microchip-lvds.c
new file mode 100644
index 000000000000..b8313dad6072
--- /dev/null
+++ b/drivers/gpu/drm/bridge/microchip-lvds.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Manikandan Muralidharan <manikandan.m@microchip.com>
+ * Author: Dharma Balasubiramani <dharma.b@microchip.com>
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/component.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_graph.h>
+#include <linux/pinctrl/devinfo.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#define LVDS_POLL_TIMEOUT_MS 1000
+
+/* LVDSC register offsets */
+#define LVDSC_CR 0x00
+#define LVDSC_CFGR 0x04
+#define LVDSC_SR 0x0C
+#define LVDSC_WPMR 0xE4
+
+/* Bitfields in LVDSC_CR (Control Register) */
+#define LVDSC_CR_SER_EN BIT(0)
+
+/* Bitfields in LVDSC_CFGR (Configuration Register) */
+#define LVDSC_CFGR_PIXSIZE_24BITS 0
+#define LVDSC_CFGR_DEN_POL_HIGH 0
+#define LVDSC_CFGR_DC_UNBALANCED 0
+#define LVDSC_CFGR_MAPPING_JEIDA BIT(6)
+
+/*Bitfields in LVDSC_SR */
+#define LVDSC_SR_CS BIT(0)
+
+/* Bitfields in LVDSC_WPMR (Write Protection Mode Register) */
+#define LVDSC_WPMR_WPKEY_MASK GENMASK(31, 8)
+#define LVDSC_WPMR_WPKEY_PSSWD 0x4C5644
+
+struct mchp_lvds {
+ struct device *dev;
+ void __iomem *regs;
+ struct clk *pclk;
+ struct drm_panel *panel;
+ struct drm_bridge bridge;
+ struct drm_bridge *panel_bridge;
+};
+
+static inline struct mchp_lvds *bridge_to_lvds(struct drm_bridge *bridge)
+{
+ return container_of(bridge, struct mchp_lvds, bridge);
+}
+
+static inline u32 lvds_readl(struct mchp_lvds *lvds, u32 offset)
+{
+ return readl_relaxed(lvds->regs + offset);
+}
+
+static inline void lvds_writel(struct mchp_lvds *lvds, u32 offset, u32 val)
+{
+ writel_relaxed(val, lvds->regs + offset);
+}
+
+static void lvds_serialiser_on(struct mchp_lvds *lvds)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(LVDS_POLL_TIMEOUT_MS);
+
+ /* The LVDSC registers can only be written if WPEN is cleared */
+ lvds_writel(lvds, LVDSC_WPMR, (LVDSC_WPMR_WPKEY_PSSWD &
+ LVDSC_WPMR_WPKEY_MASK));
+
+ /* Wait for the status of configuration registers to be changed */
+ while (lvds_readl(lvds, LVDSC_SR) & LVDSC_SR_CS) {
+ if (time_after(jiffies, timeout)) {
+ dev_err(lvds->dev, "%s: timeout error\n", __func__);
+ return;
+ }
+ usleep_range(1000, 2000);
+ }
+
+ /* Configure the LVDSC */
+ lvds_writel(lvds, LVDSC_CFGR, (LVDSC_CFGR_MAPPING_JEIDA |
+ LVDSC_CFGR_DC_UNBALANCED |
+ LVDSC_CFGR_DEN_POL_HIGH |
+ LVDSC_CFGR_PIXSIZE_24BITS));
+
+ /* Enable the LVDS serializer */
+ lvds_writel(lvds, LVDSC_CR, LVDSC_CR_SER_EN);
+}
+
+static int mchp_lvds_attach(struct drm_bridge *bridge,
+ enum drm_bridge_attach_flags flags)
+{
+ struct mchp_lvds *lvds = bridge_to_lvds(bridge);
+
+ return drm_bridge_attach(bridge->encoder, lvds->panel_bridge,
+ bridge, flags);
+}
+
+static void mchp_lvds_enable(struct drm_bridge *bridge)
+{
+ struct mchp_lvds *lvds = bridge_to_lvds(bridge);
+ int ret;
+
+ ret = clk_prepare_enable(lvds->pclk);
+ if (ret < 0) {
+ dev_err(lvds->dev, "failed to enable lvds pclk %d\n", ret);
+ return;
+ }
+
+ ret = pm_runtime_get_sync(lvds->dev);
+ if (ret < 0) {
+ dev_err(lvds->dev, "failed to get pm runtime: %d\n", ret);
+ return;
+ }
+
+ lvds_serialiser_on(lvds);
+}
+
+static void mchp_lvds_disable(struct drm_bridge *bridge)
+{
+ struct mchp_lvds *lvds = bridge_to_lvds(bridge);
+
+ pm_runtime_put(lvds->dev);
+ clk_disable_unprepare(lvds->pclk);
+}
+
+static const struct drm_bridge_funcs mchp_lvds_bridge_funcs = {
+ .attach = mchp_lvds_attach,
+ .enable = mchp_lvds_enable,
+ .disable = mchp_lvds_disable,
+};
+
+static int mchp_lvds_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct mchp_lvds *lvds;
+ struct device_node *port;
+ int ret;
+
+ if (!dev->of_node)
+ return -ENODEV;
+
+ lvds = devm_kzalloc(&pdev->dev, sizeof(*lvds), GFP_KERNEL);
+ if (!lvds)
+ return -ENOMEM;
+
+ lvds->dev = dev;
+
+ lvds->regs = devm_ioremap_resource(lvds->dev,
+ platform_get_resource(pdev, IORESOURCE_MEM, 0));
+ if (IS_ERR(lvds->regs))
+ return PTR_ERR(lvds->regs);
+
+ lvds->pclk = devm_clk_get(lvds->dev, "pclk");
+ if (IS_ERR(lvds->pclk))
+ return dev_err_probe(lvds->dev, PTR_ERR(lvds->pclk),
+ "could not get pclk_lvds\n");
+
+ port = of_graph_get_remote_node(dev->of_node, 1, 0);
+ if (!port) {
+ dev_err(dev,
+ "can't find port point, please init lvds panel port!\n");
+ return -ENODEV;
+ }
+
+ lvds->panel = of_drm_find_panel(port);
+ of_node_put(port);
+
+ if (IS_ERR(lvds->panel))
+ return -EPROBE_DEFER;
+
+ lvds->panel_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
+
+ if (IS_ERR(lvds->panel_bridge))
+ return PTR_ERR(lvds->panel_bridge);
+
+ lvds->bridge.of_node = dev->of_node;
+ lvds->bridge.type = DRM_MODE_CONNECTOR_LVDS;
+ lvds->bridge.funcs = &mchp_lvds_bridge_funcs;
+
+ dev_set_drvdata(dev, lvds);
+ ret = devm_pm_runtime_enable(dev);
+ if (ret < 0) {
+ dev_err(lvds->dev, "failed to enable pm runtime: %d\n", ret);
+ return ret;
+ }
+
+ drm_bridge_add(&lvds->bridge);
+
+ return 0;
+}
+
+static const struct of_device_id mchp_lvds_dt_ids[] = {
+ {
+ .compatible = "microchip,sam9x75-lvds",
+ },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mchp_lvds_dt_ids);
+
+static struct platform_driver mchp_lvds_driver = {
+ .probe = mchp_lvds_probe,
+ .driver = {
+ .name = "microchip-lvds",
+ .of_match_table = mchp_lvds_dt_ids,
+ },
+};
+module_platform_driver(mchp_lvds_driver);
+
+MODULE_AUTHOR("Manikandan Muralidharan <manikandan.m@microchip.com>");
+MODULE_AUTHOR("Dharma Balasubiramani <dharma.b@microchip.com>");
+MODULE_DESCRIPTION("Low Voltage Differential Signaling Controller Driver");
+MODULE_LICENSE("GPL");
--
2.25.1