target/linux/generic/backport-5.15/830-v6.7-1-leds-turris-omnia-Do-not-use-SMBUS-calls.patch

   1 From 28350bc0ac77e17365ba87d3edb2db0a79c98fdd Mon Sep 17 00:00:00 2001
   2 From: Marek Behún <kabel@kernel.org>
   3 Date: Mon, 18 Sep 2023 18:11:01 +0200
   4 Subject: leds: turris-omnia: Do not use SMBUS calls
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 The leds-turris-omnia driver uses three function for I2C access:
  10 - i2c_smbus_write_byte_data() and i2c_smbus_read_byte_data(), which
  11   cause an emulated SMBUS transfer,
  12 - i2c_master_send(), which causes an ordinary I2C transfer.
  13
  14 The Turris Omnia MCU LED controller is not semantically SMBUS, it
  15 operates as a simple I2C bus. It does not implement any of the SMBUS
  16 specific features, like PEC, or procedure calls, or anything. Moreover
  17 the I2C controller driver also does not implement SMBUS, and so the
  18 emulated SMBUS procedure from drivers/i2c/i2c-core-smbus.c is used for
  19 the SMBUS calls, which gives an unnecessary overhead.
  20
  21 When I first wrote the driver, I was unaware of these facts, and I
  22 simply used the first function that worked.
  23
  24 Drop the I2C SMBUS calls and instead use simple I2C transfers.
  25
  26 Fixes: 089381b27abe ("leds: initial support for Turris Omnia LEDs")
  27 Signed-off-by: Marek Behún <kabel@kernel.org>
  28 Link: https://lore.kernel.org/r/20230918161104.20860-2-kabel@kernel.org
  29 Signed-off-by: Lee Jones <lee@kernel.org>
  30 ---
  31  drivers/leds/leds-turris-omnia.c | 54 +++++++++++++++++++++++++++++++---------
  32  1 file changed, 42 insertions(+), 12 deletions(-)
  33
  34 --- a/drivers/leds/leds-turris-omnia.c
  35 +++ b/drivers/leds/leds-turris-omnia.c
  36 @@ -2,7 +2,7 @@
  37  /*
  38   * CZ.NIC's Turris Omnia LEDs driver
  39   *
  40 - * 2020 by Marek Behún <kabel@kernel.org>
  41 + * 2020, 2023 by Marek Behún <kabel@kernel.org>
  42   */
  43
  44  #include <linux/i2c.h>
  45 @@ -41,6 +41,37 @@ struct omnia_leds {
  46         struct omnia_led leds[];
  47  };
  48
  49 +static int omnia_cmd_write_u8(const struct i2c_client *client, u8 cmd, u8 val)
  50 +{
  51 +       u8 buf[2] = { cmd, val };
  52 +
  53 +       return i2c_master_send(client, buf, sizeof(buf));
  54 +}
  55 +
  56 +static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
  57 +{
  58 +       struct i2c_msg msgs[2];
  59 +       u8 reply;
  60 +       int ret;
  61 +
  62 +       msgs[0].addr = client->addr;
  63 +       msgs[0].flags = 0;
  64 +       msgs[0].len = 1;
  65 +       msgs[0].buf = &cmd;
  66 +       msgs[1].addr = client->addr;
  67 +       msgs[1].flags = I2C_M_RD;
  68 +       msgs[1].len = 1;
  69 +       msgs[1].buf = &reply;
  70 +
  71 +       ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  72 +       if (likely(ret == ARRAY_SIZE(msgs)))
  73 +               return reply;
  74 +       else if (ret < 0)
  75 +               return ret;
  76 +       else
  77 +               return -EIO;
  78 +}
  79 +
  80  static int omnia_led_brightness_set_blocking(struct led_classdev *cdev,
  81                                              enum led_brightness brightness)
  82  {
  83 @@ -64,7 +95,7 @@ static int omnia_led_brightness_set_bloc
  84         if (buf[2] || buf[3] || buf[4])
  85                 state |= CMD_LED_STATE_ON;
  86
  87 -       ret = i2c_smbus_write_byte_data(leds->client, CMD_LED_STATE, state);
  88 +       ret = omnia_cmd_write_u8(leds->client, CMD_LED_STATE, state);
  89         if (ret >= 0 && (state & CMD_LED_STATE_ON))
  90                 ret = i2c_master_send(leds->client, buf, 5);
  91
  92 @@ -114,9 +145,9 @@ static int omnia_led_register(struct i2c
  93         cdev->brightness_set_blocking = omnia_led_brightness_set_blocking;
  94
  95         /* put the LED into software mode */
  96 -       ret = i2c_smbus_write_byte_data(client, CMD_LED_MODE,
  97 -                                       CMD_LED_MODE_LED(led->reg) |
  98 -                                       CMD_LED_MODE_USER);
  99 +       ret = omnia_cmd_write_u8(client, CMD_LED_MODE,
 100 +                                CMD_LED_MODE_LED(led->reg) |
 101 +                                CMD_LED_MODE_USER);
 102         if (ret < 0) {
 103                 dev_err(dev, "Cannot set LED %pOF to software mode: %i\n", np,
 104                         ret);
 105 @@ -124,8 +155,8 @@ static int omnia_led_register(struct i2c
 106         }
 107
 108         /* disable the LED */
 109 -       ret = i2c_smbus_write_byte_data(client, CMD_LED_STATE,
 110 -                                       CMD_LED_STATE_LED(led->reg));
 111 +       ret = omnia_cmd_write_u8(client, CMD_LED_STATE,
 112 +                                CMD_LED_STATE_LED(led->reg));
 113         if (ret < 0) {
 114                 dev_err(dev, "Cannot set LED %pOF brightness: %i\n", np, ret);
 115                 return ret;
 116 @@ -158,7 +189,7 @@ static ssize_t brightness_show(struct de
 117         struct i2c_client *client = to_i2c_client(dev);
 118         int ret;
 119
 120 -       ret = i2c_smbus_read_byte_data(client, CMD_LED_GET_BRIGHTNESS);
 121 +       ret = omnia_cmd_read_u8(client, CMD_LED_GET_BRIGHTNESS);
 122
 123         if (ret < 0)
 124                 return ret;
 125 @@ -179,8 +210,7 @@ static ssize_t brightness_store(struct d
 126         if (brightness > 100)
 127                 return -EINVAL;
 128
 129 -       ret = i2c_smbus_write_byte_data(client, CMD_LED_SET_BRIGHTNESS,
 130 -                                       (u8)brightness);
 131 +       ret = omnia_cmd_write_u8(client, CMD_LED_SET_BRIGHTNESS, brightness);
 132
 133         return ret < 0 ? ret : count;
 134  }
 135 @@ -238,8 +268,8 @@ static int omnia_leds_remove(struct i2c_
 136         u8 buf[5];
 137
 138         /* put all LEDs into default (HW triggered) mode */
 139 -       i2c_smbus_write_byte_data(client, CMD_LED_MODE,
 140 -                                 CMD_LED_MODE_LED(OMNIA_BOARD_LEDS));
 141 +       omnia_cmd_write_u8(client, CMD_LED_MODE,
 142 +                          CMD_LED_MODE_LED(OMNIA_BOARD_LEDS));
 143
 144         /* set all LEDs color to [255, 255, 255] */
 145         buf[0] = CMD_LED_COLOR;