i2c: mux: demux-pinctrl: add driver
This driver allows an I2C bus to switch between multiple masters. This is not hot-switching because connected I2C slaves will be re-instantiated. It is meant to select the best I2C core at runtime once the task is known. Example: Prefer i2c-gpio over another I2C core because of HW errata affecting your use case. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
parent
388f7b1d6e
commit
50a5ba8769
23
Documentation/ABI/testing/sysfs-platform-i2c-demux-pinctrl
Normal file
23
Documentation/ABI/testing/sysfs-platform-i2c-demux-pinctrl
Normal file
|
@ -0,0 +1,23 @@
|
|||
What: /sys/devices/platform/<i2c-demux-name>/cur_master
|
||||
Date: January 2016
|
||||
KernelVersion: 4.6
|
||||
Contact: Wolfram Sang <wsa@the-dreams.de>
|
||||
Description:
|
||||
|
||||
This file selects the active I2C master for a demultiplexed bus.
|
||||
|
||||
Write 0 there for the first master, 1 for the second etc. Reading the file will
|
||||
give you a list with the active master marked. Example from a Renesas Lager
|
||||
board:
|
||||
|
||||
root@Lager:~# cat /sys/devices/platform/i2c@8/cur_master
|
||||
* 0 - /i2c@9
|
||||
1 - /i2c@e6520000
|
||||
2 - /i2c@e6530000
|
||||
|
||||
root@Lager:~# echo 2 > /sys/devices/platform/i2c@8/cur_master
|
||||
|
||||
root@Lager:~# cat /sys/devices/platform/i2c@8/cur_master
|
||||
0 - /i2c@9
|
||||
1 - /i2c@e6520000
|
||||
* 2 - /i2c@e6530000
|
135
Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
Normal file
135
Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
Normal file
|
@ -0,0 +1,135 @@
|
|||
Pinctrl-based I2C Bus DeMux
|
||||
|
||||
This binding describes an I2C bus demultiplexer that uses pin multiplexing to
|
||||
route the I2C signals, and represents the pin multiplexing configuration using
|
||||
the pinctrl device tree bindings. This may be used to select one I2C IP core at
|
||||
runtime which may have a better feature set for a given task than another I2C
|
||||
IP core on the SoC. The most simple example is to fall back to GPIO bitbanging
|
||||
if your current runtime configuration hits an errata of the internal IP core.
|
||||
|
||||
+-------------------------------+
|
||||
| SoC |
|
||||
| | +-----+ +-----+
|
||||
| +------------+ | | dev | | dev |
|
||||
| |I2C IP Core1|--\ | +-----+ +-----+
|
||||
| +------------+ \-------+ | | |
|
||||
| |Pinctrl|--|------+--------+
|
||||
| +------------+ +-------+ |
|
||||
| |I2C IP Core2|--/ |
|
||||
| +------------+ |
|
||||
| |
|
||||
+-------------------------------+
|
||||
|
||||
Required properties:
|
||||
- compatible: "i2c-demux-pinctrl"
|
||||
- i2c-parent: List of phandles of I2C masters available for selection. The first
|
||||
one will be used as default.
|
||||
- i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C
|
||||
parents.
|
||||
|
||||
Furthermore, I2C mux properties and child nodes. See mux.txt in this directory.
|
||||
|
||||
Example:
|
||||
|
||||
Here is a snipplet for a bus to be demuxed. It contains various i2c clients for
|
||||
HDMI, so the bus is named "i2c-hdmi":
|
||||
|
||||
i2chdmi: i2c@8 {
|
||||
|
||||
compatible = "i2c-demux-pinctrl";
|
||||
i2c-parent = <&gpioi2c>, <&iic2>, <&i2c2>;
|
||||
i2c-bus-name = "i2c-hdmi";
|
||||
#address-cells = <1>;
|
||||
#size-cells = <0>;
|
||||
|
||||
ak4643: sound-codec@12 {
|
||||
compatible = "asahi-kasei,ak4643";
|
||||
|
||||
#sound-dai-cells = <0>;
|
||||
reg = <0x12>;
|
||||
};
|
||||
|
||||
composite-in@20 {
|
||||
compatible = "adi,adv7180";
|
||||
reg = <0x20>;
|
||||
remote = <&vin1>;
|
||||
|
||||
port {
|
||||
adv7180: endpoint {
|
||||
bus-width = <8>;
|
||||
remote-endpoint = <&vin1ep0>;
|
||||
};
|
||||
};
|
||||
};
|
||||
|
||||
hdmi@39 {
|
||||
compatible = "adi,adv7511w";
|
||||
reg = <0x39>;
|
||||
interrupt-parent = <&gpio1>;
|
||||
interrupts = <15 IRQ_TYPE_LEVEL_LOW>;
|
||||
|
||||
adi,input-depth = <8>;
|
||||
adi,input-colorspace = "rgb";
|
||||
adi,input-clock = "1x";
|
||||
adi,input-style = <1>;
|
||||
adi,input-justification = "evenly";
|
||||
|
||||
ports {
|
||||
#address-cells = <1>;
|
||||
#size-cells = <0>;
|
||||
|
||||
port@0 {
|
||||
reg = <0>;
|
||||
adv7511_in: endpoint {
|
||||
remote-endpoint = <&du_out_lvds0>;
|
||||
};
|
||||
};
|
||||
|
||||
port@1 {
|
||||
reg = <1>;
|
||||
adv7511_out: endpoint {
|
||||
remote-endpoint = <&hdmi_con>;
|
||||
};
|
||||
};
|
||||
};
|
||||
};
|
||||
};
|
||||
|
||||
And for clarification, here are the snipplets for the i2c-parents:
|
||||
|
||||
gpioi2c: i2c@9 {
|
||||
#address-cells = <1>;
|
||||
#size-cells = <0>;
|
||||
compatible = "i2c-gpio";
|
||||
status = "disabled";
|
||||
gpios = <&gpio5 6 GPIO_ACTIVE_HIGH /* sda */
|
||||
&gpio5 5 GPIO_ACTIVE_HIGH /* scl */
|
||||
>;
|
||||
i2c-gpio,delay-us = <5>;
|
||||
};
|
||||
|
||||
...
|
||||
|
||||
&i2c2 {
|
||||
pinctrl-0 = <&i2c2_pins>;
|
||||
pinctrl-names = "i2c-hdmi";
|
||||
|
||||
clock-frequency = <100000>;
|
||||
};
|
||||
|
||||
...
|
||||
|
||||
&iic2 {
|
||||
pinctrl-0 = <&iic2_pins>;
|
||||
pinctrl-names = "i2c-hdmi";
|
||||
|
||||
clock-frequency = <100000>;
|
||||
};
|
||||
|
||||
Please note:
|
||||
|
||||
- pinctrl properties for the parent I2C controllers need a pinctrl state
|
||||
with the same name as i2c-bus-name, not "default"!
|
||||
|
||||
- the i2c masters must have their status "disabled". This driver will
|
||||
enable them at runtime when needed.
|
|
@ -72,4 +72,13 @@ config I2C_MUX_REG
|
|||
This driver can also be built as a module. If so, the module
|
||||
will be called i2c-mux-reg.
|
||||
|
||||
config I2C_DEMUX_PINCTRL
|
||||
tristate "pinctrl-based I2C demultiplexer"
|
||||
depends on PINCTRL && OF
|
||||
select OF_DYNAMIC
|
||||
help
|
||||
If you say yes to this option, support will be included for an I2C
|
||||
demultiplexer that uses the pinctrl subsystem. This is useful if you
|
||||
want to change the I2C master at run-time depending on features.
|
||||
|
||||
endmenu
|
||||
|
|
|
@ -3,6 +3,8 @@
|
|||
|
||||
obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o
|
||||
|
||||
obj-$(CONFIG_I2C_DEMUX_PINCTRL) += i2c-demux-pinctrl.o
|
||||
|
||||
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
|
||||
|
|
272
drivers/i2c/muxes/i2c-demux-pinctrl.c
Normal file
272
drivers/i2c/muxes/i2c-demux-pinctrl.c
Normal file
|
@ -0,0 +1,272 @@
|
|||
/*
|
||||
* Pinctrl based I2C DeMultiplexer
|
||||
*
|
||||
* Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
|
||||
* Copyright (C) 2015-16 by Renesas Electronics Corporation
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify it
|
||||
* under the terms of the GNU General Public License as published by the
|
||||
* Free Software Foundation; version 2 of the License.
|
||||
*
|
||||
* See the bindings doc for DTS setup and the sysfs doc for usage information.
|
||||
* (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
|
||||
*/
|
||||
|
||||
#include <linux/i2c.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/of.h>
|
||||
#include <linux/pinctrl/consumer.h>
|
||||
#include <linux/platform_device.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/sysfs.h>
|
||||
|
||||
struct i2c_demux_pinctrl_chan {
|
||||
struct device_node *parent_np;
|
||||
struct i2c_adapter *parent_adap;
|
||||
struct of_changeset chgset;
|
||||
};
|
||||
|
||||
struct i2c_demux_pinctrl_priv {
|
||||
int cur_chan;
|
||||
int num_chan;
|
||||
struct device *dev;
|
||||
const char *bus_name;
|
||||
struct i2c_adapter cur_adap;
|
||||
struct i2c_algorithm algo;
|
||||
struct i2c_demux_pinctrl_chan chan[];
|
||||
};
|
||||
|
||||
static struct property status_okay = { .name = "status", .length = 3, .value = "ok" };
|
||||
|
||||
static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
|
||||
{
|
||||
struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
|
||||
struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
|
||||
|
||||
return __i2c_transfer(parent, msgs, num);
|
||||
}
|
||||
|
||||
static u32 i2c_demux_functionality(struct i2c_adapter *adap)
|
||||
{
|
||||
struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
|
||||
struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
|
||||
|
||||
return parent->algo->functionality(parent);
|
||||
}
|
||||
|
||||
static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
|
||||
{
|
||||
struct i2c_adapter *adap;
|
||||
struct pinctrl *p;
|
||||
int ret;
|
||||
|
||||
ret = of_changeset_apply(&priv->chan[new_chan].chgset);
|
||||
if (ret)
|
||||
goto err;
|
||||
|
||||
adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
|
||||
if (!adap) {
|
||||
ret = -ENODEV;
|
||||
goto err;
|
||||
}
|
||||
|
||||
p = devm_pinctrl_get_select(adap->dev.parent, priv->bus_name);
|
||||
if (IS_ERR(p)) {
|
||||
ret = PTR_ERR(p);
|
||||
goto err_with_put;
|
||||
}
|
||||
|
||||
priv->chan[new_chan].parent_adap = adap;
|
||||
priv->cur_chan = new_chan;
|
||||
|
||||
/* Now fill out current adapter structure. cur_chan must be up to date */
|
||||
priv->algo.master_xfer = i2c_demux_master_xfer;
|
||||
priv->algo.functionality = i2c_demux_functionality;
|
||||
|
||||
snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
|
||||
"i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
|
||||
priv->cur_adap.owner = THIS_MODULE;
|
||||
priv->cur_adap.algo = &priv->algo;
|
||||
priv->cur_adap.algo_data = priv;
|
||||
priv->cur_adap.dev.parent = priv->dev;
|
||||
priv->cur_adap.class = adap->class;
|
||||
priv->cur_adap.retries = adap->retries;
|
||||
priv->cur_adap.timeout = adap->timeout;
|
||||
priv->cur_adap.quirks = adap->quirks;
|
||||
priv->cur_adap.dev.of_node = priv->dev->of_node;
|
||||
ret = i2c_add_adapter(&priv->cur_adap);
|
||||
if (ret < 0)
|
||||
goto err_with_put;
|
||||
|
||||
return 0;
|
||||
|
||||
err_with_put:
|
||||
i2c_put_adapter(adap);
|
||||
err:
|
||||
dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
|
||||
{
|
||||
int ret, cur = priv->cur_chan;
|
||||
|
||||
if (cur < 0)
|
||||
return 0;
|
||||
|
||||
i2c_del_adapter(&priv->cur_adap);
|
||||
i2c_put_adapter(priv->chan[cur].parent_adap);
|
||||
|
||||
ret = of_changeset_revert(&priv->chan[cur].chgset);
|
||||
|
||||
priv->chan[cur].parent_adap = NULL;
|
||||
priv->cur_chan = -EINVAL;
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
|
||||
{
|
||||
int ret;
|
||||
|
||||
if (new_chan == priv->cur_chan)
|
||||
return 0;
|
||||
|
||||
ret = i2c_demux_deactivate_master(priv);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
||||
return i2c_demux_activate_master(priv, new_chan);
|
||||
}
|
||||
|
||||
static ssize_t cur_master_show(struct device *dev, struct device_attribute *attr,
|
||||
char *buf)
|
||||
{
|
||||
struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
|
||||
int count = 0, i;
|
||||
|
||||
for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
|
||||
count += scnprintf(buf + count, PAGE_SIZE - count, "%c %d - %s\n",
|
||||
i == priv->cur_chan ? '*' : ' ', i,
|
||||
priv->chan[i].parent_np->full_name);
|
||||
|
||||
return count;
|
||||
}
|
||||
|
||||
static ssize_t cur_master_store(struct device *dev, struct device_attribute *attr,
|
||||
const char *buf, size_t count)
|
||||
{
|
||||
struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
|
||||
unsigned int val;
|
||||
int ret;
|
||||
|
||||
ret = kstrtouint(buf, 0, &val);
|
||||
if (ret < 0)
|
||||
return ret;
|
||||
|
||||
if (val >= priv->num_chan)
|
||||
return -EINVAL;
|
||||
|
||||
ret = i2c_demux_change_master(priv, val);
|
||||
|
||||
return ret < 0 ? ret : count;
|
||||
}
|
||||
static DEVICE_ATTR_RW(cur_master);
|
||||
|
||||
static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
|
||||
{
|
||||
struct device_node *np = pdev->dev.of_node;
|
||||
struct i2c_demux_pinctrl_priv *priv;
|
||||
int num_chan, i, j, err;
|
||||
|
||||
num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
|
||||
if (num_chan < 2) {
|
||||
dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
|
||||
+ num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
|
||||
if (!priv)
|
||||
return -ENOMEM;
|
||||
|
||||
err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
for (i = 0; i < num_chan; i++) {
|
||||
struct device_node *adap_np;
|
||||
|
||||
adap_np = of_parse_phandle(np, "i2c-parent", i);
|
||||
if (!adap_np) {
|
||||
dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
|
||||
err = -ENOENT;
|
||||
goto err_rollback;
|
||||
}
|
||||
priv->chan[i].parent_np = adap_np;
|
||||
|
||||
of_changeset_init(&priv->chan[i].chgset);
|
||||
of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay);
|
||||
}
|
||||
|
||||
priv->num_chan = num_chan;
|
||||
priv->dev = &pdev->dev;
|
||||
|
||||
platform_set_drvdata(pdev, priv);
|
||||
|
||||
/* switch to first parent as active master */
|
||||
i2c_demux_activate_master(priv, 0);
|
||||
|
||||
err = device_create_file(&pdev->dev, &dev_attr_cur_master);
|
||||
if (err)
|
||||
goto err_rollback;
|
||||
|
||||
return 0;
|
||||
|
||||
err_rollback:
|
||||
for (j = 0; j < i; j++) {
|
||||
of_node_put(priv->chan[j].parent_np);
|
||||
of_changeset_destroy(&priv->chan[j].chgset);
|
||||
}
|
||||
|
||||
return err;
|
||||
}
|
||||
|
||||
static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
|
||||
{
|
||||
struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
|
||||
int i;
|
||||
|
||||
device_remove_file(&pdev->dev, &dev_attr_cur_master);
|
||||
|
||||
i2c_demux_deactivate_master(priv);
|
||||
|
||||
for (i = 0; i < priv->num_chan; i++) {
|
||||
of_node_put(priv->chan[i].parent_np);
|
||||
of_changeset_destroy(&priv->chan[i].chgset);
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
|
||||
{ .compatible = "i2c-demux-pinctrl", },
|
||||
{},
|
||||
};
|
||||
MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
|
||||
|
||||
static struct platform_driver i2c_demux_pinctrl_driver = {
|
||||
.driver = {
|
||||
.name = "i2c-demux-pinctrl",
|
||||
.of_match_table = i2c_demux_pinctrl_of_match,
|
||||
},
|
||||
.probe = i2c_demux_pinctrl_probe,
|
||||
.remove = i2c_demux_pinctrl_remove,
|
||||
};
|
||||
module_platform_driver(i2c_demux_pinctrl_driver);
|
||||
|
||||
MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
|
||||
MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
|
||||
MODULE_LICENSE("GPL v2");
|
||||
MODULE_ALIAS("platform:i2c-demux-pinctrl");
|
Loading…
Reference in a new issue