i2c: mux: Add register-based mux i2c-mux-reg
Based on i2c-mux-gpio driver, similarly the register-based mux switch from one bus to another by setting a single register. The register can be on PCIe bus, local bus, or any memory-mapped address. The endianness of such register can be specified in device tree if used, or in platform data. Signed-off-by: York Sun <yorksun@freescale.com> Acked-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
York Sun
Wolfram Sang
parent
7a59b00a09
commit
b3fdd32799
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@ -0,0 +1,74 @@
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Register-based I2C Bus Mux
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This binding describes an I2C bus multiplexer that uses a single register
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to route the I2C signals.
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Required properties:
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- compatible: i2c-mux-reg
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- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
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port is connected to.
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* Standard I2C mux properties. See mux.txt in this directory.
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* I2C child bus nodes. See mux.txt in this directory.
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Optional properties:
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- reg: this pair of <offset size> specifies the register to control the mux.
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The <offset size> depends on its parent node. It can be any memory-mapped
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address. The size must be either 1, 2, or 4 bytes. If reg is omitted, the
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resource of this device will be used.
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- little-endian: The existence indicates the register is in little endian.
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- big-endian: The existence indicates the register is in big endian.
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If both little-endian and big-endian are omitted, the endianness of the
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CPU will be used.
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- write-only: The existence indicates the register is write-only.
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- idle-state: value to set the muxer to when idle. When no value is
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given, it defaults to the last value used.
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Whenever an access is made to a device on a child bus, the value set
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in the revelant node's reg property will be output to the register.
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If an idle state is defined, using the idle-state (optional) property,
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whenever an access is not being made to a device on a child bus, the
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register will be set according to the idle value.
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If an idle state is not defined, the most recently used value will be
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left programmed into the register.
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Example of a mux on PCIe card, the host is a powerpc SoC (big endian):
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i2c-mux {
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/* the <offset size> depends on the address translation
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* of the parent device. If omitted, device resource
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* will be used instead. The size is to determine
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* whether iowrite32, iowrite16, or iowrite8 will be used.
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*/
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reg = <0x6028 0x4>;
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little-endian; /* little endian register on PCIe */
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compatible = "i2c-mux-reg";
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#address-cells = <1>;
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#size-cells = <0>;
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i2c-parent = <&i2c1>;
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i2c@0 {
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reg = <0>;
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#address-cells = <1>;
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#size-cells = <0>;
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si5338: clock-generator@70 {
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compatible = "silabs,si5338";
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reg = <0x70>;
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/* other stuff */
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};
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};
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i2c@1 {
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/* data is written using iowrite32 */
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reg = <1>;
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#address-cells = <1>;
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#size-cells = <0>;
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si5338: clock-generator@70 {
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compatible = "silabs,si5338";
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reg = <0x70>;
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/* other stuff */
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};
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};
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};
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@ -61,4 +61,15 @@ config I2C_MUX_PINCTRL
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This driver can also be built as a module. If so, the module will be
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called pinctrl-i2cmux.
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config I2C_MUX_REG
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tristate "Register-based I2C multiplexer"
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help
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If you say yes to this option, support will be included for a
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register based I2C multiplexer. This driver provides access to
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I2C busses connected through a MUX, which is controlled
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by a single register.
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This driver can also be built as a module. If so, the module
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will be called i2c-mux-reg.
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endmenu
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@ -7,5 +7,6 @@ obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
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obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
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obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
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obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
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obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
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ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
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@ -0,0 +1,294 @@
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/*
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* I2C multiplexer using a single register
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*
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* Copyright 2015 Freescale Semiconductor
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* York Sun <yorksun@freescale.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/i2c.h>
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#include <linux/i2c-mux.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/platform_data/i2c-mux-reg.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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struct regmux {
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struct i2c_adapter *parent;
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struct i2c_adapter **adap; /* child busses */
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struct i2c_mux_reg_platform_data data;
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};
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static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
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{
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if (!mux->data.reg)
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return -EINVAL;
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switch (mux->data.reg_size) {
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case 4:
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if (mux->data.little_endian) {
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iowrite32(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread32(mux->data.reg);
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} else {
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iowrite32be(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread32(mux->data.reg);
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}
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break;
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case 2:
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if (mux->data.little_endian) {
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iowrite16(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread16(mux->data.reg);
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} else {
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iowrite16be(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread16be(mux->data.reg);
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}
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break;
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case 1:
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iowrite8(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread8(mux->data.reg);
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break;
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default:
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pr_err("Invalid register size\n");
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return -EINVAL;
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}
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return 0;
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}
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static int i2c_mux_reg_select(struct i2c_adapter *adap, void *data,
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unsigned int chan)
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{
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struct regmux *mux = data;
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return i2c_mux_reg_set(mux, chan);
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}
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static int i2c_mux_reg_deselect(struct i2c_adapter *adap, void *data,
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unsigned int chan)
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{
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struct regmux *mux = data;
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if (mux->data.idle_in_use)
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return i2c_mux_reg_set(mux, mux->data.idle);
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return 0;
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}
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#ifdef CONFIG_OF
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static int i2c_mux_reg_probe_dt(struct regmux *mux,
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struct platform_device *pdev)
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{
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struct device_node *np = pdev->dev.of_node;
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struct device_node *adapter_np, *child;
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struct i2c_adapter *adapter;
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struct resource res;
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unsigned *values;
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int i = 0;
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if (!np)
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return -ENODEV;
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adapter_np = of_parse_phandle(np, "i2c-parent", 0);
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if (!adapter_np) {
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dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
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return -ENODEV;
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}
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adapter = of_find_i2c_adapter_by_node(adapter_np);
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if (!adapter)
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return -EPROBE_DEFER;
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mux->parent = adapter;
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mux->data.parent = i2c_adapter_id(adapter);
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put_device(&adapter->dev);
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mux->data.n_values = of_get_child_count(np);
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if (of_find_property(np, "little-endian", NULL)) {
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mux->data.little_endian = true;
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} else if (of_find_property(np, "big-endian", NULL)) {
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mux->data.little_endian = false;
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} else {
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#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
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defined(__LITTLE_ENDIAN)
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mux->data.little_endian = true;
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#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
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defined(__BIG_ENDIAN)
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mux->data.little_endian = false;
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#else
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#error Endianness not defined?
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#endif
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}
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if (of_find_property(np, "write-only", NULL))
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mux->data.write_only = true;
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else
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mux->data.write_only = false;
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values = devm_kzalloc(&pdev->dev,
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sizeof(*mux->data.values) * mux->data.n_values,
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GFP_KERNEL);
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if (!values) {
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dev_err(&pdev->dev, "Cannot allocate values array");
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return -ENOMEM;
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}
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for_each_child_of_node(np, child) {
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of_property_read_u32(child, "reg", values + i);
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i++;
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}
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mux->data.values = values;
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if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
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mux->data.idle_in_use = true;
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/* map address from "reg" if exists */
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if (of_address_to_resource(np, 0, &res)) {
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mux->data.reg_size = resource_size(&res);
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if (mux->data.reg_size > 4) {
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dev_err(&pdev->dev, "Invalid address size\n");
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return -EINVAL;
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}
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mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
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if (IS_ERR(mux->data.reg))
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return PTR_ERR(mux->data.reg);
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}
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return 0;
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}
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#else
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static int i2c_mux_reg_probe_dt(struct gpiomux *mux,
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struct platform_device *pdev)
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{
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return 0;
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}
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#endif
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static int i2c_mux_reg_probe(struct platform_device *pdev)
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{
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struct regmux *mux;
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struct i2c_adapter *parent;
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struct resource *res;
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int (*deselect)(struct i2c_adapter *, void *, u32);
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unsigned int class;
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int i, ret, nr;
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mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
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if (!mux)
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return -ENOMEM;
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platform_set_drvdata(pdev, mux);
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if (dev_get_platdata(&pdev->dev)) {
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memcpy(&mux->data, dev_get_platdata(&pdev->dev),
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sizeof(mux->data));
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parent = i2c_get_adapter(mux->data.parent);
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if (!parent)
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return -EPROBE_DEFER;
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mux->parent = parent;
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} else {
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ret = i2c_mux_reg_probe_dt(mux, pdev);
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if (ret < 0) {
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dev_err(&pdev->dev, "Error parsing device tree");
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return ret;
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}
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}
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if (!mux->data.reg) {
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dev_info(&pdev->dev,
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"Register not set, using platform resource\n");
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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mux->data.reg_size = resource_size(res);
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if (mux->data.reg_size > 4) {
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dev_err(&pdev->dev, "Invalid resource size\n");
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return -EINVAL;
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}
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mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(mux->data.reg))
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return PTR_ERR(mux->data.reg);
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}
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mux->adap = devm_kzalloc(&pdev->dev,
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sizeof(*mux->adap) * mux->data.n_values,
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GFP_KERNEL);
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if (!mux->adap) {
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dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
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return -ENOMEM;
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}
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if (mux->data.idle_in_use)
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deselect = i2c_mux_reg_deselect;
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else
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deselect = NULL;
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for (i = 0; i < mux->data.n_values; i++) {
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nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
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class = mux->data.classes ? mux->data.classes[i] : 0;
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mux->adap[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, mux,
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nr, mux->data.values[i],
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class, i2c_mux_reg_select,
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deselect);
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if (!mux->adap[i]) {
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ret = -ENODEV;
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dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
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goto add_adapter_failed;
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}
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}
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dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
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mux->data.n_values, mux->parent->name);
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return 0;
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add_adapter_failed:
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for (; i > 0; i--)
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i2c_del_mux_adapter(mux->adap[i - 1]);
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return ret;
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}
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static int i2c_mux_reg_remove(struct platform_device *pdev)
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{
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struct regmux *mux = platform_get_drvdata(pdev);
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int i;
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for (i = 0; i < mux->data.n_values; i++)
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i2c_del_mux_adapter(mux->adap[i]);
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i2c_put_adapter(mux->parent);
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return 0;
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}
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static const struct of_device_id i2c_mux_reg_of_match[] = {
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{ .compatible = "i2c-mux-reg", },
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
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static struct platform_driver i2c_mux_reg_driver = {
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.probe = i2c_mux_reg_probe,
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.remove = i2c_mux_reg_remove,
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.driver = {
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.name = "i2c-mux-reg",
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},
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};
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module_platform_driver(i2c_mux_reg_driver);
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MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
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MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:i2c-mux-reg");
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@ -0,0 +1,44 @@
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/*
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* I2C multiplexer using a single register
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*
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* Copyright 2015 Freescale Semiconductor
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* York Sun <yorksun@freescale.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#ifndef __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
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#define __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
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/**
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* struct i2c_mux_reg_platform_data - Platform-dependent data for i2c-mux-reg
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* @parent: Parent I2C bus adapter number
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* @base_nr: Base I2C bus number to number adapters from or zero for dynamic
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* @values: Array of value for each channel
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* @n_values: Number of multiplexer channels
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* @little_endian: Indicating if the register is in little endian
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* @write_only: Reading the register is not allowed by hardware
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* @classes: Optional I2C auto-detection classes
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* @idle: Value to write to mux when idle
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* @idle_in_use: indicate if idle value is in use
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* @reg: Virtual address of the register to switch channel
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* @reg_size: register size in bytes
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*/
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struct i2c_mux_reg_platform_data {
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int parent;
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int base_nr;
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const unsigned int *values;
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int n_values;
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bool little_endian;
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bool write_only;
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const unsigned int *classes;
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u32 idle;
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bool idle_in_use;
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void __iomem *reg;
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resource_size_t reg_size;
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};
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#endif /* __LINUX_PLATFORM_DATA_I2C_MUX_REG_H */
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