drivers/video/bridge/ps862x.c

   1 /*
   2  * Copyright (C) 2015 Google, Inc
   3  * Written by Simon Glass <sjg@chromium.org>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9 #include <dm.h>
  10 #include <errno.h>
  11 #include <i2c.h>
  12 #include <video_bridge.h>
  13 #include <power/regulator.h>
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 /*
  18  * Initialisation of the chip is a process of writing certain values into
  19  * certain registers over i2c bus. The chip in fact responds to a range of
  20  * addresses on the i2c bus, so for each written value three parameters are
  21  * required: i2c address, register address and the actual value.
  22  *
  23  * The base address is derived from the device tree, but oddly the chip
  24  * responds on several addresses with different register sets for each.
  25  */
  26
  27 /**
  28  * ps8622_write() Write a PS8622 eDP bridge i2c register
  29  *
  30  * @param dev           I2C device
  31  * @param addr_off      offset from the i2c base address for ps8622
  32  * @param reg_addr      register address to write
  33  * @param value         value to be written
  34  * @return 0 on success, non-0 on failure
  35  */
  36 static int ps8622_write(struct udevice *dev, unsigned addr_off,
  37                         unsigned char reg_addr, unsigned char value)
  38 {
  39         struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
  40         uint8_t buf[2];
  41         struct i2c_msg msg;
  42         int ret;
  43
  44         msg.addr = chip->chip_addr + addr_off;
  45         msg.flags = 0;
  46         buf[0] = reg_addr;
  47         buf[1] = value;
  48         msg.buf = buf;
  49         msg.len = 2;
  50         ret = dm_i2c_xfer(dev, &msg, 1);
  51         if (ret) {
  52                 debug("%s: write failed, reg=%#x, value=%#x, ret=%d\n",
  53                       __func__, reg_addr, value, ret);
  54                 return ret;
  55         }
  56
  57         return 0;
  58 }
  59
  60 static int ps8622_set_backlight(struct udevice *dev, int percent)
  61 {
  62         int level = percent * 255 / 100;
  63
  64         debug("%s: level=%d\n", __func__, level);
  65         return ps8622_write(dev, 0x01, 0xa7, level);
  66 }
  67
  68 static int ps8622_attach(struct udevice *dev)
  69 {
  70         const uint8_t *params;
  71         struct udevice *reg;
  72         int ret, i, len;
  73
  74         debug("%s: %s\n", __func__, dev->name);
  75         /* set the LDO providing the 1.2V rail to the Parade bridge */
  76         ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
  77                                            "power-supply", &reg);
  78         if (!ret) {
  79                 ret = regulator_autoset(reg);
  80         } else if (ret != -ENOENT) {
  81                 debug("%s: Failed to enable power: ret=%d\n", __func__, ret);
  82                 return ret;
  83         }
  84
  85         ret = video_bridge_set_active(dev, true);
  86         if (ret)
  87                 return ret;
  88
  89         params = fdt_getprop(gd->fdt_blob, dev_of_offset(dev), "parade,regs",
  90                              &len);
  91         if (!params || len % 3) {
  92                 debug("%s: missing/invalid params=%p, len=%x\n", __func__,
  93                       params, len);
  94                 return -EINVAL;
  95         }
  96
  97         /* need to wait 20ms after power on before doing I2C writes */
  98         mdelay(20);
  99         for (i = 0; i < len; i += 3) {
 100                 ret = ps8622_write(dev, params[i + 0], params[i + 1],
 101                                    params[i + 2]);
 102                 if (ret)
 103                         return ret;
 104         }
 105
 106         return 0;
 107 }
 108
 109 static int ps8622_probe(struct udevice *dev)
 110 {
 111         debug("%s\n", __func__);
 112         if (device_get_uclass_id(dev->parent) != UCLASS_I2C)
 113                 return -EPROTONOSUPPORT;
 114
 115         return 0;
 116 }
 117
 118 struct video_bridge_ops ps8622_ops = {
 119         .attach = ps8622_attach,
 120         .set_backlight = ps8622_set_backlight,
 121 };
 122
 123 static const struct udevice_id ps8622_ids[] = {
 124         { .compatible = "parade,ps8622", },
 125         { .compatible = "parade,ps8625", },
 126         { }
 127 };
 128
 129 U_BOOT_DRIVER(parade_ps8622) = {
 130         .name   = "parade_ps8622",
 131         .id     = UCLASS_VIDEO_BRIDGE,
 132         .of_match = ps8622_ids,
 133         .probe  = ps8622_probe,
 134         .ops    = &ps8622_ops,
 135 };