On 26/04/2024 18:49, Farouk Bouabid wrote:
> Mule is an mcu that emulates a set of i2c devices which are reacheable
> through an i2c-mux.
>
> The emulated devices share a single i2c address with the mux itself where
> the requested register is what determines which logic is executed (mux or
> device):
>
> 1- The devices on the mux can be selected (mux function) by writing the
> appropriate device number to an i2c config register (0xff) that is not
> used by any device logic.
>
> 2- Any access to a register other than the config register will be
> handled by the previously selected device.
>
> Signed-off-by: Farouk Bouabid <farouk.bouabid@xxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/i2c/muxes/Kconfig | 11 +++
> drivers/i2c/muxes/Makefile | 1 +
> drivers/i2c/muxes/i2c-mux-mule.c | 157 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 169 insertions(+)
>
> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
> index db1b9057612a..593a20a6ac51 100644
> --- a/drivers/i2c/muxes/Kconfig
> +++ b/drivers/i2c/muxes/Kconfig
> @@ -119,4 +119,15 @@ config I2C_MUX_MLXCPLD
> This driver can also be built as a module. If so, the module
> will be called i2c-mux-mlxcpld.
>
> +config I2C_MUX_MULE
> + tristate "Mule I2C device multiplexer"
> + depends on OF
> + help
> + If you say yes to this option, support will be included for a
> + Mule I2C device multiplexer. This driver provides access to
> + I2C devices connected on the Mule I2C mux.
Describe what is Mule. Here and in bindings documentation.
> +
> + This driver can also be built as a module. If so, the module
> + will be called i2c-mux-mule.
> +
> endmenu
> diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
> index 6d9d865e8518..4b24f49515a7 100644
> --- a/drivers/i2c/muxes/Makefile
> +++ b/drivers/i2c/muxes/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
> obj-$(CONFIG_I2C_MUX_GPMUX) += i2c-mux-gpmux.o
> obj-$(CONFIG_I2C_MUX_LTC4306) += i2c-mux-ltc4306.o
> obj-$(CONFIG_I2C_MUX_MLXCPLD) += i2c-mux-mlxcpld.o
> +obj-$(CONFIG_I2C_MUX_MULE) += i2c-mux-mule.o
> obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
> obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
> obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
> diff --git a/drivers/i2c/muxes/i2c-mux-mule.c b/drivers/i2c/muxes/i2c-mux-mule.c
> new file mode 100644
> index 000000000000..da2a9526522e
> --- /dev/null
> +++ b/drivers/i2c/muxes/i2c-mux-mule.c
> @@ -0,0 +1,157 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Mule I2C device multiplexer
> + *
> + * Copyright (C) 2024 Theobroma Systems Design und Consulting GmbH
> + */
> +
> +#include <linux/i2c-mux.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +
> +#define MUX_CONFIG_REG 0xff
> +#define MUX_DEFAULT_DEV 0x0
> +
> +struct mule_i2c_reg_mux {
> + struct regmap *regmap;
> +};
> +
> +static const struct regmap_config mule_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> +};
> +
> +static const struct of_device_id mule_i2c_mux_of_match[] = {
> + {.compatible = "tsd,mule-i2c-mux",},
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, mule_i2c_mux_of_match);
This goes after or before probe. Don't introduce unusual coding style.
> +
...
> +static void mux_remove(void *data)
> +{
> + struct i2c_mux_core *muxc = data;
> +
> + i2c_mux_del_adapters(muxc);
> +
> + mux_deselect(muxc, MUX_DEFAULT_DEV);
> +}
> +
> +static int mule_i2c_mux_probe(struct i2c_client *client)
> +{
> + struct i2c_adapter *adap = client->adapter;
> + struct mule_i2c_reg_mux *priv;
> + struct i2c_mux_core *muxc;
> + struct device_node *dev;
> + unsigned int readback;
> + bool old_fw;
> + int ndev, ret;
> +
> + /* Count devices on the mux */
> + ndev = of_get_child_count(client->dev.of_node);
> + dev_dbg(&client->dev, "%u devices on the mux\n", ndev);
> +
> + muxc = i2c_mux_alloc(adap, &client->dev,
> + ndev, sizeof(*priv),
> + I2C_MUX_LOCKED,
> + mux_select, mux_deselect);
Very odd alignment. This is absolutely unreadable.
Please properly align with opening (.
> + if (!muxc)
> + return -ENOMEM;
> +
> + muxc->share_addr_with_children = 1;
> + priv = i2c_mux_priv(muxc);
> +
> + priv->regmap = devm_regmap_init_i2c(client, &mule_regmap_config);
> + if (IS_ERR(priv->regmap))
> + return dev_err_probe(&client->dev, PTR_ERR(priv->regmap),
> + "Failed to allocate i2c register map\n");
> +
> + i2c_set_clientdata(client, muxc);
> +
> + /*
> + * Mux 0 is guaranteed to exist on all old and new mule fw.
> + * mule fw without mux support will accept write ops to the
> + * config register, but readback returns 0xff (register not updated).
> + */
> + ret = mux_select(muxc, 0);
> + if (ret)
> + return ret;
> +
> + ret = regmap_read(priv->regmap, MUX_CONFIG_REG, &readback);
> + if (ret)
> + return ret;
> +
> + old_fw = (readback == 0);
> +
> + ret = devm_add_action_or_reset(&client->dev, mux_remove, muxc);
This is really odd. Why do you call remove callback as devm action?
I have serious doubts this was really tested.
> + if (ret)
> + return ret;
> +
> + /* Create device adapters */
> + for_each_child_of_node(client->dev.of_node, dev) {
> + u32 reg;
> +
> + ret = of_property_read_u32(dev, "reg", ®);
> + if (ret) {
> + dev_err(&client->dev, "No reg property found for %s: %d\n",
> + of_node_full_name(dev), ret);
Very odd alignment. Please properly align with opening (.
> + return ret;
> + }
> +
> + if (!old_fw && reg != 0) {
> + dev_warn(&client->dev,
> + "Mux %d not supported, please update Mule FW\n", reg);
> + continue;
> + }
> +
> + ret = mux_select(muxc, reg);
> + if (ret) {
> + dev_warn(&client->dev,
> + "Mux %d not supported, please update Mule FW\n", reg);
> + continue;
> + }
> +
> + ret = i2c_mux_add_adapter(muxc, 0, reg, 0);
> + if (ret) {
> + dev_err(&client->dev, "Failed to add i2c mux adapter %d: %d\n", reg, ret);
> + return ret;
> + }
> + }
> +
> + mux_deselect(muxc, MUX_DEFAULT_DEV);
> +
> + return 0;
> +}
> +
> +static struct i2c_driver mule_i2c_mux_driver = {
> + .driver = {
> + .name = "mule-i2c-mux",
> + .of_match_table = mule_i2c_mux_of_match,
> + },
> + .probe = mule_i2c_mux_probe,
> +};
> +
Anyway, all this looks like i2c-mux-reg. Please provide rationale in
commit msg WHY you need one more driver.
Best regards,
Krzysztof
