dm: video: Add support for the Parade PS8622/625 bridge
This chip provides an eDP to LVDS bridge which is useful for SoCs that don't
support LVDS displays (or it would waste scarce pins). The setup is included
in the device tree.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/bridge/ps862x.c b/drivers/video/bridge/ps862x.c
new file mode 100644
index 0000000..80f63e3
--- /dev/null
+++ b/drivers/video/bridge/ps862x.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <i2c.h>
+#include <video_bridge.h>
+#include <power/regulator.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * Initialisation of the chip is a process of writing certain values into
+ * certain registers over i2c bus. The chip in fact responds to a range of
+ * addresses on the i2c bus, so for each written value three parameters are
+ * required: i2c address, register address and the actual value.
+ *
+ * The base address is derived from the device tree, but oddly the chip
+ * responds on several addresses with different register sets for each.
+ */
+
+/**
+ * ps8622_write() Write a PS8622 eDP bridge i2c register
+ *
+ * @param dev I2C device
+ * @param addr_off offset from the i2c base address for ps8622
+ * @param reg_addr register address to write
+ * @param value value to be written
+ * @return 0 on success, non-0 on failure
+ */
+static int ps8622_write(struct udevice *dev, unsigned addr_off,
+ unsigned char reg_addr, unsigned char value)
+{
+ struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
+ uint8_t buf[2];
+ struct i2c_msg msg;
+ int ret;
+
+ msg.addr = chip->chip_addr + addr_off;
+ msg.flags = 0;
+ buf[0] = reg_addr;
+ buf[1] = value;
+ msg.buf = buf;
+ msg.len = 2;
+ ret = dm_i2c_xfer(dev, &msg, 1);
+ if (ret) {
+ debug("%s: write failed, reg=%#x, value=%#x, ret=%d\n",
+ __func__, reg_addr, value, ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int ps8622_set_backlight(struct udevice *dev, int percent)
+{
+ int level = percent * 255 / 100;
+
+ debug("%s: level=%d\n", __func__, level);
+ return ps8622_write(dev, 0x01, 0xa7, level);
+}
+
+static int ps8622_attach(struct udevice *dev)
+{
+ const uint8_t *params;
+ struct udevice *reg;
+ int ret, i, len;
+
+ debug("%s: %s\n", __func__, dev->name);
+ /* set the LDO providing the 1.2V rail to the Parade bridge */
+ ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
+ "power-supply", ®);
+ if (!ret) {
+ ret = regulator_autoset(reg);
+ } else if (ret != -ENOENT) {
+ debug("%s: Failed to enable power: ret=%d\n", __func__, ret);
+ return ret;
+ }
+
+ ret = video_bridge_set_active(dev, true);
+ if (ret)
+ return ret;
+
+ params = fdt_getprop(gd->fdt_blob, dev->of_offset, "parade,regs", &len);
+ if (!params || len % 3) {
+ debug("%s: missing/invalid params=%p, len=%x\n", __func__,
+ params, len);
+ return -EINVAL;
+ }
+
+ /* need to wait 20ms after power on before doing I2C writes */
+ mdelay(20);
+ for (i = 0; i < len; i += 3) {
+ ret = ps8622_write(dev, params[i + 0], params[i + 1],
+ params[i + 2]);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int ps8622_probe(struct udevice *dev)
+{
+ debug("%s\n", __func__);
+ if (device_get_uclass_id(dev->parent) != UCLASS_I2C)
+ return -EPROTONOSUPPORT;
+
+ return 0;
+}
+
+struct video_bridge_ops ps8622_ops = {
+ .attach = ps8622_attach,
+ .set_backlight = ps8622_set_backlight,
+};
+
+static const struct udevice_id ps8622_ids[] = {
+ { .compatible = "parade,ps8622", },
+ { .compatible = "parade,ps8625", },
+ { }
+};
+
+U_BOOT_DRIVER(parade_ps8622) = {
+ .name = "parade_ps8622",
+ .id = UCLASS_VIDEO_BRIDGE,
+ .of_match = ps8622_ids,
+ .probe = ps8622_probe,
+ .ops = &ps8622_ops,
+};