-From 28350bc0ac77e17365ba87d3edb2db0a79c98fdd Mon Sep 17 00:00:00 2001
-From: Marek Behún <kabel@kernel.org>
-Date: Mon, 18 Sep 2023 18:11:01 +0200
-Subject: leds: turris-omnia: Do not use SMBUS calls
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-The leds-turris-omnia driver uses three function for I2C access:
-- i2c_smbus_write_byte_data() and i2c_smbus_read_byte_data(), which
- cause an emulated SMBUS transfer,
-- i2c_master_send(), which causes an ordinary I2C transfer.
-
-The Turris Omnia MCU LED controller is not semantically SMBUS, it
-operates as a simple I2C bus. It does not implement any of the SMBUS
-specific features, like PEC, or procedure calls, or anything. Moreover
-the I2C controller driver also does not implement SMBUS, and so the
-emulated SMBUS procedure from drivers/i2c/i2c-core-smbus.c is used for
-the SMBUS calls, which gives an unnecessary overhead.
-
-When I first wrote the driver, I was unaware of these facts, and I
-simply used the first function that worked.
-
-Drop the I2C SMBUS calls and instead use simple I2C transfers.
-
-Fixes: 089381b27abe ("leds: initial support for Turris Omnia LEDs")
-Signed-off-by: Marek Behún <kabel@kernel.org>
-Link: https://lore.kernel.org/r/20230918161104.20860-2-kabel@kernel.org
-Signed-off-by: Lee Jones <lee@kernel.org>
----
- drivers/leds/leds-turris-omnia.c | 54 +++++++++++++++++++++++++++++++---------
- 1 file changed, 42 insertions(+), 12 deletions(-)
-
---- a/drivers/leds/leds-turris-omnia.c
-+++ b/drivers/leds/leds-turris-omnia.c
-@@ -2,7 +2,7 @@
- /*
- * CZ.NIC's Turris Omnia LEDs driver
- *
-- * 2020 by Marek Behún <kabel@kernel.org>
-+ * 2020, 2023 by Marek Behún <kabel@kernel.org>
- */
-
- #include <linux/i2c.h>
-@@ -41,6 +41,37 @@ struct omnia_leds {
- struct omnia_led leds[];
- };
-
-+static int omnia_cmd_write_u8(const struct i2c_client *client, u8 cmd, u8 val)
-+{
-+ u8 buf[2] = { cmd, val };
-+
-+ return i2c_master_send(client, buf, sizeof(buf));
-+}
-+
-+static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
-+{
-+ struct i2c_msg msgs[2];
-+ u8 reply;
-+ int ret;
-+
-+ msgs[0].addr = client->addr;
-+ msgs[0].flags = 0;
-+ msgs[0].len = 1;
-+ msgs[0].buf = &cmd;
-+ msgs[1].addr = client->addr;
-+ msgs[1].flags = I2C_M_RD;
-+ msgs[1].len = 1;
-+ msgs[1].buf = &reply;
-+
-+ ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
-+ if (likely(ret == ARRAY_SIZE(msgs)))
-+ return reply;
-+ else if (ret < 0)
-+ return ret;
-+ else
-+ return -EIO;
-+}
-+
- static int omnia_led_brightness_set_blocking(struct led_classdev *cdev,
- enum led_brightness brightness)
- {
-@@ -64,7 +95,7 @@ static int omnia_led_brightness_set_bloc
- if (buf[2] || buf[3] || buf[4])
- state |= CMD_LED_STATE_ON;
-
-- ret = i2c_smbus_write_byte_data(leds->client, CMD_LED_STATE, state);
-+ ret = omnia_cmd_write_u8(leds->client, CMD_LED_STATE, state);
- if (ret >= 0 && (state & CMD_LED_STATE_ON))
- ret = i2c_master_send(leds->client, buf, 5);
-
-@@ -114,9 +145,9 @@ static int omnia_led_register(struct i2c
- cdev->brightness_set_blocking = omnia_led_brightness_set_blocking;
-
- /* put the LED into software mode */
-- ret = i2c_smbus_write_byte_data(client, CMD_LED_MODE,
-- CMD_LED_MODE_LED(led->reg) |
-- CMD_LED_MODE_USER);
-+ ret = omnia_cmd_write_u8(client, CMD_LED_MODE,
-+ CMD_LED_MODE_LED(led->reg) |
-+ CMD_LED_MODE_USER);
- if (ret < 0) {
- dev_err(dev, "Cannot set LED %pOF to software mode: %i\n", np,
- ret);
-@@ -124,8 +155,8 @@ static int omnia_led_register(struct i2c
- }
-
- /* disable the LED */
-- ret = i2c_smbus_write_byte_data(client, CMD_LED_STATE,
-- CMD_LED_STATE_LED(led->reg));
-+ ret = omnia_cmd_write_u8(client, CMD_LED_STATE,
-+ CMD_LED_STATE_LED(led->reg));
- if (ret < 0) {
- dev_err(dev, "Cannot set LED %pOF brightness: %i\n", np, ret);
- return ret;
-@@ -158,7 +189,7 @@ static ssize_t brightness_show(struct de
- struct i2c_client *client = to_i2c_client(dev);
- int ret;
-
-- ret = i2c_smbus_read_byte_data(client, CMD_LED_GET_BRIGHTNESS);
-+ ret = omnia_cmd_read_u8(client, CMD_LED_GET_BRIGHTNESS);
-
- if (ret < 0)
- return ret;
-@@ -179,8 +210,7 @@ static ssize_t brightness_store(struct d
- if (brightness > 100)
- return -EINVAL;
-
-- ret = i2c_smbus_write_byte_data(client, CMD_LED_SET_BRIGHTNESS,
-- (u8)brightness);
-+ ret = omnia_cmd_write_u8(client, CMD_LED_SET_BRIGHTNESS, brightness);
-
- return ret < 0 ? ret : count;
- }
-@@ -238,8 +268,8 @@ static int omnia_leds_remove(struct i2c_
- u8 buf[5];
-
- /* put all LEDs into default (HW triggered) mode */
-- i2c_smbus_write_byte_data(client, CMD_LED_MODE,
-- CMD_LED_MODE_LED(OMNIA_BOARD_LEDS));
-+ omnia_cmd_write_u8(client, CMD_LED_MODE,
-+ CMD_LED_MODE_LED(OMNIA_BOARD_LEDS));
-
- /* set all LEDs color to [255, 255, 255] */
- buf[0] = CMD_LED_COLOR;