target/linux/generic/backport-5.10/842-v5.15-leds-pca955x-implement-the-default-state-property.patch

   1 From e46cb6d0c760a5b15e38138845fad99628fafcb8 Mon Sep 17 00:00:00 2001
   2 From: Eddie James <eajames@linux.ibm.com>
   3 Date: Fri, 16 Jul 2021 17:03:29 -0500
   4 Subject: [PATCH] leds: pca955x: Implement the default-state property
   5
   6 In order to retain the LED state after a system reboot, check the
   7 documented default-state device tree property during initialization.
   8 Modify the behavior of the probe according to the property.
   9
  10 Signed-off-by: Eddie James <eajames@linux.ibm.com>
  11 Signed-off-by: Pavel Machek <pavel@ucw.cz>
  12 ---
  13  drivers/leds/leds-pca955x.c | 54 +++++++++++++++++++++++++++++++------
  14  1 file changed, 46 insertions(+), 8 deletions(-)
  15
  16 --- a/drivers/leds/leds-pca955x.c
  17 +++ b/drivers/leds/leds-pca955x.c
  18 @@ -129,6 +129,7 @@ struct pca955x_led {
  19         int                     led_num;        /* 0 .. 15 potentially */
  20         char                    name[32];
  21         u32                     type;
  22 +       int                     default_state;
  23         const char              *default_trigger;
  24  };
  25
  26 @@ -439,6 +440,7 @@ pca955x_get_pdata(struct i2c_client *cli
  27
  28         device_for_each_child_node(&client->dev, child) {
  29                 const char *name;
  30 +               const char *state;
  31                 u32 reg;
  32                 int res;
  33
  34 @@ -457,6 +459,18 @@ pca955x_get_pdata(struct i2c_client *cli
  35                 fwnode_property_read_u32(child, "type", &led->type);
  36                 fwnode_property_read_string(child, "linux,default-trigger",
  37                                             &led->default_trigger);
  38 +
  39 +               if (!fwnode_property_read_string(child, "default-state",
  40 +                                                &state)) {
  41 +                       if (!strcmp(state, "keep"))
  42 +                               led->default_state = LEDS_GPIO_DEFSTATE_KEEP;
  43 +                       else if (!strcmp(state, "on"))
  44 +                               led->default_state = LEDS_GPIO_DEFSTATE_ON;
  45 +                       else
  46 +                               led->default_state = LEDS_GPIO_DEFSTATE_OFF;
  47 +               } else {
  48 +                       led->default_state = LEDS_GPIO_DEFSTATE_OFF;
  49 +               }
  50         }
  51
  52         pdata->num_leds = chip->bits;
  53 @@ -485,6 +499,7 @@ static int pca955x_probe(struct i2c_clie
  54         int i, err;
  55         struct pca955x_platform_data *pdata;
  56         int ngpios = 0;
  57 +       bool keep_pwm = false;
  58
  59         chip = &pca955x_chipdefs[id->driver_data];
  60         adapter = client->adapter;
  61 @@ -565,14 +580,35 @@ static int pca955x_probe(struct i2c_clie
  62                         led->brightness_set_blocking = pca955x_led_set;
  63                         led->brightness_get = pca955x_led_get;
  64
  65 +                       if (pdata->leds[i].default_state ==
  66 +                           LEDS_GPIO_DEFSTATE_OFF) {
  67 +                               err = pca955x_led_set(led, LED_OFF);
  68 +                               if (err)
  69 +                                       return err;
  70 +                       } else if (pdata->leds[i].default_state ==
  71 +                                  LEDS_GPIO_DEFSTATE_ON) {
  72 +                               err = pca955x_led_set(led, LED_FULL);
  73 +                               if (err)
  74 +                                       return err;
  75 +                       }
  76 +
  77                         err = devm_led_classdev_register(&client->dev, led);
  78                         if (err)
  79                                 return err;
  80
  81 -                       /* Turn off LED */
  82 -                       err = pca955x_led_set(led, LED_OFF);
  83 -                       if (err)
  84 -                               return err;
  85 +                       /*
  86 +                        * For default-state == "keep", let the core update the
  87 +                        * brightness from the hardware, then check the
  88 +                        * brightness to see if it's using PWM1. If so, PWM1
  89 +                        * should not be written below.
  90 +                        */
  91 +                       if (pdata->leds[i].default_state ==
  92 +                           LEDS_GPIO_DEFSTATE_KEEP) {
  93 +                               if (led->brightness != LED_FULL &&
  94 +                                   led->brightness != LED_OFF &&
  95 +                                   led->brightness != LED_HALF)
  96 +                                       keep_pwm = true;
  97 +                       }
  98                 }
  99         }
 100
 101 @@ -581,10 +617,12 @@ static int pca955x_probe(struct i2c_clie
 102         if (err)
 103                 return err;
 104
 105 -       /* PWM1 is used for variable brightness, default to OFF */
 106 -       err = pca955x_write_pwm(client, 1, 0);
 107 -       if (err)
 108 -               return err;
 109 +       if (!keep_pwm) {
 110 +               /* PWM1 is used for variable brightness, default to OFF */
 111 +               err = pca955x_write_pwm(client, 1, 0);
 112 +               if (err)
 113 +                       return err;
 114 +       }
 115
 116         /* Set to fast frequency so we do not see flashing */
 117         err = pca955x_write_psc(client, 0, 0);