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Message-ID: <80883dd5-2be0-4f8b-8298-ca076e6ac558@cherry.de>
Date: Tue, 11 Jun 2024 18:52:39 +0200
From: Farouk Bouabid <farouk.bouabid@...rry.de>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>,
Peter Rosin <peda@...ntia.se>, Andi Shyti <andi.shyti@...nel.org>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, Quentin Schulz
<quentin.schulz@...rry.de>, Heiko Stuebner <heiko@...ech.de>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v3 3/7] i2c: muxes: add support for mule i2c multiplexer
Hi all,
On 11.06.24 13:43, Farouk Bouabid wrote:
> Mule is an MCU that emulates a set of I2C devices which are reachable
> 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 logic or device logic):
>
> 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@...rry.de>
> ---
> drivers/i2c/muxes/Kconfig | 18 +++++
> drivers/i2c/muxes/Makefile | 1 +
> drivers/i2c/muxes/i2c-mux-mule.c | 157 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 176 insertions(+)
>
> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
> index db1b9057612a..70876259796d 100644
> --- a/drivers/i2c/muxes/Kconfig
> +++ b/drivers/i2c/muxes/Kconfig
> @@ -119,4 +119,22 @@ 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
> + Mule is an MCU that emulates a set of I2C devices which are reachable
> + 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 logic or device logic).
> +
> + 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.
> +
> + 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..db27fa560995
> --- /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 inline int __mux_select(struct regmap *regmap, u32 dev)
> +{
> + return regmap_write(regmap, MUX_CONFIG_REG, dev);
> +}
> +
> +static int mux_select(struct i2c_mux_core *muxc, u32 dev)
> +{
> + struct mule_i2c_reg_mux *mux = muxc->priv;
> +
> + return __mux_select(mux->regmap, dev);
> +}
> +
> +static int mux_deselect(struct i2c_mux_core *muxc, u32 dev)
> +{
> + return mux_select(muxc, MUX_DEFAULT_DEV);
> +}
> +
> +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;
> + int ndev, ret;
> + bool old_fw;
> +
> + /* 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);
> + 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);
> + 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);
> + 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);
The class parameter was recently removed from this function but I forgot
to remove it. Sorry for the noise, I will send a v4 for this fix.
Cheers,
Farouk
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