From ae58d1e406986f31d1e88b32f5ac601506c196d8 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Fri, 18 May 2012 09:29:34 -0600 Subject: [PATCH] i2c: Add generic I2C multiplexer using pinctrl API This is useful for SoCs whose I2C module's signals can be routed to different sets of pins at run-time, using the pinctrl API. +-----+ +-----+ | dev | | dev | +------------------------+ +-----+ +-----+ | SoC | | | | /----|------+--------+ | +---+ +------+ | child bus A, on first set of pins | |I2C|---|Pinmux| | | +---+ +------+ | child bus B, on second set of pins | \----|------+--------+--------+ | | | | | +------------------------+ +-----+ +-----+ +-----+ | dev | | dev | | dev | +-----+ +-----+ +-----+ Signed-off-by: Stephen Warren Acked-by: Linus Walleij Acked-by: Rob Herring Signed-off-by: Wolfram Sang --- .../bindings/i2c/i2c-mux-pinctrl.txt | 93 ++++++ drivers/i2c/muxes/Kconfig | 12 + drivers/i2c/muxes/Makefile | 1 + drivers/i2c/muxes/i2c-mux-pinctrl.c | 279 ++++++++++++++++++ include/linux/i2c-mux-pinctrl.h | 41 +++ 5 files changed, 426 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt create mode 100644 drivers/i2c/muxes/i2c-mux-pinctrl.c create mode 100644 include/linux/i2c-mux-pinctrl.h diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt new file mode 100644 index 00000000000..ae8af1694e9 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt @@ -0,0 +1,93 @@ +Pinctrl-based I2C Bus Mux + +This binding describes an I2C bus multiplexer that uses pin multiplexing to +route the I2C signals, and represents the pin multiplexing configuration +using the pinctrl device tree bindings. + + +-----+ +-----+ + | dev | | dev | + +------------------------+ +-----+ +-----+ + | SoC | | | + | /----|------+--------+ + | +---+ +------+ | child bus A, on first set of pins + | |I2C|---|Pinmux| | + | +---+ +------+ | child bus B, on second set of pins + | \----|------+--------+--------+ + | | | | | + +------------------------+ +-----+ +-----+ +-----+ + | dev | | dev | | dev | + +-----+ +-----+ +-----+ + +Required properties: +- compatible: i2c-mux-pinctrl +- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side + port is connected to. + +Also required are: + +* Standard pinctrl properties that specify the pin mux state for each child + bus. See ../pinctrl/pinctrl-bindings.txt. + +* Standard I2C mux properties. See mux.txt in this directory. + +* I2C child bus nodes. See mux.txt in this directory. + +For each named state defined in the pinctrl-names property, an I2C child bus +will be created. I2C child bus numbers are assigned based on the index into +the pinctrl-names property. + +The only exception is that no bus will be created for a state named "idle". If +such a state is defined, it must be the last entry in pinctrl-names. For +example: + + pinctrl-names = "ddc", "pta", "idle" -> ddc = bus 0, pta = bus 1 + pinctrl-names = "ddc", "idle", "pta" -> Invalid ("idle" not last) + pinctrl-names = "idle", "ddc", "pta" -> Invalid ("idle" not last) + +Whenever an access is made to a device on a child bus, the relevant pinctrl +state will be programmed into hardware. + +If an idle state is defined, whenever an access is not being made to a device +on a child bus, the idle pinctrl state will be programmed into hardware. + +If an idle state is not defined, the most recently used pinctrl state will be +left programmed into hardware whenever no access is being made of a device on +a child bus. + +Example: + + i2cmux { + compatible = "i2c-mux-pinctrl"; + #address-cells = <1>; + #size-cells = <0>; + + i2c-parent = <&i2c1>; + + pinctrl-names = "ddc", "pta", "idle"; + pinctrl-0 = <&state_i2cmux_ddc>; + pinctrl-1 = <&state_i2cmux_pta>; + pinctrl-2 = <&state_i2cmux_idle>; + + i2c@0 { + reg = <0>; + #address-cells = <1>; + #size-cells = <0>; + + eeprom { + compatible = "eeprom"; + reg = <0x50>; + }; + }; + + i2c@1 { + reg = <1>; + #address-cells = <1>; + #size-cells = <0>; + + eeprom { + compatible = "eeprom"; + reg = <0x50>; + }; + }; + }; + diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig index beb2491db27..a0edd985421 100644 --- a/drivers/i2c/muxes/Kconfig +++ b/drivers/i2c/muxes/Kconfig @@ -37,4 +37,16 @@ config I2C_MUX_PCA954x This driver can also be built as a module. If so, the module will be called i2c-mux-pca954x. +config I2C_MUX_PINCTRL + tristate "pinctrl-based I2C multiplexer" + depends on PINCTRL + help + If you say yes to this option, support will be included for an I2C + multiplexer that uses the pinctrl subsystem, i.e. pin multiplexing. + This is useful for SoCs whose I2C module's signals can be routed to + different sets of pins at run-time. + + This driver can also be built as a module. If so, the module will be + called pinctrl-i2cmux. + endmenu diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile index 5826249b29c..76da8692aff 100644 --- a/drivers/i2c/muxes/Makefile +++ b/drivers/i2c/muxes/Makefile @@ -4,5 +4,6 @@ obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o obj-$(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 ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c new file mode 100644 index 00000000000..46a66976347 --- /dev/null +++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c @@ -0,0 +1,279 @@ +/* + * I2C multiplexer using pinctrl API + * + * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct i2c_mux_pinctrl { + struct device *dev; + struct i2c_mux_pinctrl_platform_data *pdata; + struct pinctrl *pinctrl; + struct pinctrl_state **states; + struct pinctrl_state *state_idle; + struct i2c_adapter *parent; + struct i2c_adapter **busses; +}; + +static int i2c_mux_pinctrl_select(struct i2c_adapter *adap, void *data, + u32 chan) +{ + struct i2c_mux_pinctrl *mux = data; + + return pinctrl_select_state(mux->pinctrl, mux->states[chan]); +} + +static int i2c_mux_pinctrl_deselect(struct i2c_adapter *adap, void *data, + u32 chan) +{ + struct i2c_mux_pinctrl *mux = data; + + return pinctrl_select_state(mux->pinctrl, mux->state_idle); +} + +#ifdef CONFIG_OF +static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux, + struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + int num_names, i, ret; + struct device_node *adapter_np; + struct i2c_adapter *adapter; + + if (!np) + return 0; + + mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL); + if (!mux->pdata) { + dev_err(mux->dev, + "Cannot allocate i2c_mux_pinctrl_platform_data\n"); + return -ENOMEM; + } + + num_names = of_property_count_strings(np, "pinctrl-names"); + if (num_names < 0) { + dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n", + num_names); + return num_names; + } + + mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev, + sizeof(*mux->pdata->pinctrl_states) * num_names, + GFP_KERNEL); + if (!mux->pdata->pinctrl_states) { + dev_err(mux->dev, "Cannot allocate pinctrl_states\n"); + return -ENOMEM; + } + + for (i = 0; i < num_names; i++) { + ret = of_property_read_string_index(np, "pinctrl-names", i, + &mux->pdata->pinctrl_states[mux->pdata->bus_count]); + if (ret < 0) { + dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n", + ret); + return ret; + } + if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count], + "idle")) { + if (i != num_names - 1) { + dev_err(mux->dev, "idle state must be last\n"); + return -EINVAL; + } + mux->pdata->pinctrl_state_idle = "idle"; + } else { + mux->pdata->bus_count++; + } + } + + adapter_np = of_parse_phandle(np, "i2c-parent", 0); + if (!adapter_np) { + dev_err(mux->dev, "Cannot parse i2c-parent\n"); + return -ENODEV; + } + adapter = of_find_i2c_adapter_by_node(adapter_np); + if (!adapter) { + dev_err(mux->dev, "Cannot find parent bus\n"); + return -ENODEV; + } + mux->pdata->parent_bus_num = i2c_adapter_id(adapter); + put_device(&adapter->dev); + + return 0; +} +#else +static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux, + struct platform_device *pdev) +{ + return 0; +} +#endif + +static int __devinit i2c_mux_pinctrl_probe(struct platform_device *pdev) +{ + struct i2c_mux_pinctrl *mux; + int (*deselect)(struct i2c_adapter *, void *, u32); + int i, ret; + + mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); + if (!mux) { + dev_err(&pdev->dev, "Cannot allocate i2c_mux_pinctrl\n"); + ret = -ENOMEM; + goto err; + } + platform_set_drvdata(pdev, mux); + + mux->dev = &pdev->dev; + + mux->pdata = pdev->dev.platform_data; + if (!mux->pdata) { + ret = i2c_mux_pinctrl_parse_dt(mux, pdev); + if (ret < 0) + goto err; + } + if (!mux->pdata) { + dev_err(&pdev->dev, "Missing platform data\n"); + ret = -ENODEV; + goto err; + } + + mux->states = devm_kzalloc(&pdev->dev, + sizeof(*mux->states) * mux->pdata->bus_count, + GFP_KERNEL); + if (!mux->states) { + dev_err(&pdev->dev, "Cannot allocate states\n"); + ret = -ENOMEM; + goto err; + } + + mux->busses = devm_kzalloc(&pdev->dev, + sizeof(mux->busses) * mux->pdata->bus_count, + GFP_KERNEL); + if (!mux->states) { + dev_err(&pdev->dev, "Cannot allocate busses\n"); + ret = -ENOMEM; + goto err; + } + + mux->pinctrl = devm_pinctrl_get(&pdev->dev); + if (IS_ERR(mux->pinctrl)) { + ret = PTR_ERR(mux->pinctrl); + dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret); + goto err; + } + for (i = 0; i < mux->pdata->bus_count; i++) { + mux->states[i] = pinctrl_lookup_state(mux->pinctrl, + mux->pdata->pinctrl_states[i]); + if (IS_ERR(mux->states[i])) { + ret = PTR_ERR(mux->states[i]); + dev_err(&pdev->dev, + "Cannot look up pinctrl state %s: %d\n", + mux->pdata->pinctrl_states[i], ret); + goto err; + } + } + if (mux->pdata->pinctrl_state_idle) { + mux->state_idle = pinctrl_lookup_state(mux->pinctrl, + mux->pdata->pinctrl_state_idle); + if (IS_ERR(mux->state_idle)) { + ret = PTR_ERR(mux->state_idle); + dev_err(&pdev->dev, + "Cannot look up pinctrl state %s: %d\n", + mux->pdata->pinctrl_state_idle, ret); + goto err; + } + + deselect = i2c_mux_pinctrl_deselect; + } else { + deselect = NULL; + } + + mux->parent = i2c_get_adapter(mux->pdata->parent_bus_num); + if (!mux->parent) { + dev_err(&pdev->dev, "Parent adapter (%d) not found\n", + mux->pdata->parent_bus_num); + ret = -ENODEV; + goto err; + } + + for (i = 0; i < mux->pdata->bus_count; i++) { + u32 bus = mux->pdata->base_bus_num ? + (mux->pdata->base_bus_num + i) : 0; + + mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, + mux, bus, i, + i2c_mux_pinctrl_select, + deselect); + if (!mux->busses[i]) { + ret = -ENODEV; + dev_err(&pdev->dev, "Failed to add adapter %d\n", i); + goto err_del_adapter; + } + } + + return 0; + +err_del_adapter: + for (; i > 0; i--) + i2c_del_mux_adapter(mux->busses[i - 1]); + i2c_put_adapter(mux->parent); +err: + return ret; +} + +static int __devexit i2c_mux_pinctrl_remove(struct platform_device *pdev) +{ + struct i2c_mux_pinctrl *mux = platform_get_drvdata(pdev); + int i; + + for (i = 0; i < mux->pdata->bus_count; i++) + i2c_del_mux_adapter(mux->busses[i]); + + i2c_put_adapter(mux->parent); + + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id i2c_mux_pinctrl_of_match[] __devinitconst = { + { .compatible = "i2c-mux-pinctrl", }, + {}, +}; +MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match); +#endif + +static struct platform_driver i2c_mux_pinctrl_driver = { + .driver = { + .name = "i2c-mux-pinctrl", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match), + }, + .probe = i2c_mux_pinctrl_probe, + .remove = __devexit_p(i2c_mux_pinctrl_remove), +}; +module_platform_driver(i2c_mux_pinctrl_driver); + +MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver"); +MODULE_AUTHOR("Stephen Warren "); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:i2c-mux-pinctrl"); diff --git a/include/linux/i2c-mux-pinctrl.h b/include/linux/i2c-mux-pinctrl.h new file mode 100644 index 00000000000..a65c86429e8 --- /dev/null +++ b/include/linux/i2c-mux-pinctrl.h @@ -0,0 +1,41 @@ +/* + * i2c-mux-pinctrl platform data + * + * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +#ifndef _LINUX_I2C_MUX_PINCTRL_H +#define _LINUX_I2C_MUX_PINCTRL_H + +/** + * struct i2c_mux_pinctrl_platform_data - Platform data for i2c-mux-pinctrl + * @parent_bus_num: Parent I2C bus number + * @base_bus_num: Base I2C bus number for the child busses. 0 for dynamic. + * @bus_count: Number of child busses. Also the number of elements in + * @pinctrl_states + * @pinctrl_states: The names of the pinctrl state to select for each child bus + * @pinctrl_state_idle: The pinctrl state to select when no child bus is being + * accessed. If NULL, the most recently used pinctrl state will be left + * selected. + */ +struct i2c_mux_pinctrl_platform_data { + int parent_bus_num; + int base_bus_num; + int bus_count; + const char **pinctrl_states; + const char *pinctrl_state_idle; +}; + +#endif -- 2.41.0