mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 09:19:51 +00:00
![York Sun](/assets/img/avatar_default.png)
Reading the register (if allowed) after writing is to ensure writing is completed on a posted bus. The endianness of reading doesn't matter. Signed-off-by: York Sun <yorksun@freescale.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
290 lines
6.9 KiB
C
290 lines
6.9 KiB
C
/*
|
|
* I2C multiplexer using a single register
|
|
*
|
|
* Copyright 2015 Freescale Semiconductor
|
|
* York Sun <yorksun@freescale.com>
|
|
*
|
|
* 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; either version 2 of the License, or (at your
|
|
* option) any later version.
|
|
*/
|
|
|
|
#include <linux/i2c.h>
|
|
#include <linux/i2c-mux.h>
|
|
#include <linux/init.h>
|
|
#include <linux/io.h>
|
|
#include <linux/module.h>
|
|
#include <linux/of_address.h>
|
|
#include <linux/platform_data/i2c-mux-reg.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/slab.h>
|
|
|
|
struct regmux {
|
|
struct i2c_adapter *parent;
|
|
struct i2c_adapter **adap; /* child busses */
|
|
struct i2c_mux_reg_platform_data data;
|
|
};
|
|
|
|
static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
|
|
{
|
|
if (!mux->data.reg)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Write to the register, followed by a read to ensure the write is
|
|
* completed on a "posted" bus, for example PCI or write buffers.
|
|
* The endianness of reading doesn't matter and the return data
|
|
* is not used.
|
|
*/
|
|
switch (mux->data.reg_size) {
|
|
case 4:
|
|
if (mux->data.little_endian)
|
|
iowrite32(chan_id, mux->data.reg);
|
|
else
|
|
iowrite32be(chan_id, mux->data.reg);
|
|
if (!mux->data.write_only)
|
|
ioread32(mux->data.reg);
|
|
break;
|
|
case 2:
|
|
if (mux->data.little_endian)
|
|
iowrite16(chan_id, mux->data.reg);
|
|
else
|
|
iowrite16be(chan_id, mux->data.reg);
|
|
if (!mux->data.write_only)
|
|
ioread16(mux->data.reg);
|
|
break;
|
|
case 1:
|
|
iowrite8(chan_id, mux->data.reg);
|
|
if (!mux->data.write_only)
|
|
ioread8(mux->data.reg);
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int i2c_mux_reg_select(struct i2c_adapter *adap, void *data,
|
|
unsigned int chan)
|
|
{
|
|
struct regmux *mux = data;
|
|
|
|
return i2c_mux_reg_set(mux, chan);
|
|
}
|
|
|
|
static int i2c_mux_reg_deselect(struct i2c_adapter *adap, void *data,
|
|
unsigned int chan)
|
|
{
|
|
struct regmux *mux = data;
|
|
|
|
if (mux->data.idle_in_use)
|
|
return i2c_mux_reg_set(mux, mux->data.idle);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_OF
|
|
static int i2c_mux_reg_probe_dt(struct regmux *mux,
|
|
struct platform_device *pdev)
|
|
{
|
|
struct device_node *np = pdev->dev.of_node;
|
|
struct device_node *adapter_np, *child;
|
|
struct i2c_adapter *adapter;
|
|
struct resource res;
|
|
unsigned *values;
|
|
int i = 0;
|
|
|
|
if (!np)
|
|
return -ENODEV;
|
|
|
|
adapter_np = of_parse_phandle(np, "i2c-parent", 0);
|
|
if (!adapter_np) {
|
|
dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
|
|
return -ENODEV;
|
|
}
|
|
adapter = of_find_i2c_adapter_by_node(adapter_np);
|
|
of_node_put(adapter_np);
|
|
if (!adapter)
|
|
return -EPROBE_DEFER;
|
|
|
|
mux->parent = adapter;
|
|
mux->data.parent = i2c_adapter_id(adapter);
|
|
put_device(&adapter->dev);
|
|
|
|
mux->data.n_values = of_get_child_count(np);
|
|
if (of_find_property(np, "little-endian", NULL)) {
|
|
mux->data.little_endian = true;
|
|
} else if (of_find_property(np, "big-endian", NULL)) {
|
|
mux->data.little_endian = false;
|
|
} else {
|
|
#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
|
|
defined(__LITTLE_ENDIAN)
|
|
mux->data.little_endian = true;
|
|
#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
|
|
defined(__BIG_ENDIAN)
|
|
mux->data.little_endian = false;
|
|
#else
|
|
#error Endianness not defined?
|
|
#endif
|
|
}
|
|
if (of_find_property(np, "write-only", NULL))
|
|
mux->data.write_only = true;
|
|
else
|
|
mux->data.write_only = false;
|
|
|
|
values = devm_kzalloc(&pdev->dev,
|
|
sizeof(*mux->data.values) * mux->data.n_values,
|
|
GFP_KERNEL);
|
|
if (!values) {
|
|
dev_err(&pdev->dev, "Cannot allocate values array");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
for_each_child_of_node(np, child) {
|
|
of_property_read_u32(child, "reg", values + i);
|
|
i++;
|
|
}
|
|
mux->data.values = values;
|
|
|
|
if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
|
|
mux->data.idle_in_use = true;
|
|
|
|
/* map address from "reg" if exists */
|
|
if (of_address_to_resource(np, 0, &res)) {
|
|
mux->data.reg_size = resource_size(&res);
|
|
mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
|
|
if (IS_ERR(mux->data.reg))
|
|
return PTR_ERR(mux->data.reg);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#else
|
|
static int i2c_mux_reg_probe_dt(struct regmux *mux,
|
|
struct platform_device *pdev)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static int i2c_mux_reg_probe(struct platform_device *pdev)
|
|
{
|
|
struct regmux *mux;
|
|
struct i2c_adapter *parent;
|
|
struct resource *res;
|
|
int (*deselect)(struct i2c_adapter *, void *, u32);
|
|
unsigned int class;
|
|
int i, ret, nr;
|
|
|
|
mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
|
|
if (!mux)
|
|
return -ENOMEM;
|
|
|
|
platform_set_drvdata(pdev, mux);
|
|
|
|
if (dev_get_platdata(&pdev->dev)) {
|
|
memcpy(&mux->data, dev_get_platdata(&pdev->dev),
|
|
sizeof(mux->data));
|
|
|
|
parent = i2c_get_adapter(mux->data.parent);
|
|
if (!parent)
|
|
return -EPROBE_DEFER;
|
|
|
|
mux->parent = parent;
|
|
} else {
|
|
ret = i2c_mux_reg_probe_dt(mux, pdev);
|
|
if (ret < 0) {
|
|
dev_err(&pdev->dev, "Error parsing device tree");
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (!mux->data.reg) {
|
|
dev_info(&pdev->dev,
|
|
"Register not set, using platform resource\n");
|
|
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
|
|
mux->data.reg_size = resource_size(res);
|
|
mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
|
|
if (IS_ERR(mux->data.reg))
|
|
return PTR_ERR(mux->data.reg);
|
|
}
|
|
|
|
if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
|
|
mux->data.reg_size != 1) {
|
|
dev_err(&pdev->dev, "Invalid register size\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
mux->adap = devm_kzalloc(&pdev->dev,
|
|
sizeof(*mux->adap) * mux->data.n_values,
|
|
GFP_KERNEL);
|
|
if (!mux->adap) {
|
|
dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (mux->data.idle_in_use)
|
|
deselect = i2c_mux_reg_deselect;
|
|
else
|
|
deselect = NULL;
|
|
|
|
for (i = 0; i < mux->data.n_values; i++) {
|
|
nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
|
|
class = mux->data.classes ? mux->data.classes[i] : 0;
|
|
|
|
mux->adap[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, mux,
|
|
nr, mux->data.values[i],
|
|
class, i2c_mux_reg_select,
|
|
deselect);
|
|
if (!mux->adap[i]) {
|
|
ret = -ENODEV;
|
|
dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
|
|
goto add_adapter_failed;
|
|
}
|
|
}
|
|
|
|
dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
|
|
mux->data.n_values, mux->parent->name);
|
|
|
|
return 0;
|
|
|
|
add_adapter_failed:
|
|
for (; i > 0; i--)
|
|
i2c_del_mux_adapter(mux->adap[i - 1]);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int i2c_mux_reg_remove(struct platform_device *pdev)
|
|
{
|
|
struct regmux *mux = platform_get_drvdata(pdev);
|
|
int i;
|
|
|
|
for (i = 0; i < mux->data.n_values; i++)
|
|
i2c_del_mux_adapter(mux->adap[i]);
|
|
|
|
i2c_put_adapter(mux->parent);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct of_device_id i2c_mux_reg_of_match[] = {
|
|
{ .compatible = "i2c-mux-reg", },
|
|
{},
|
|
};
|
|
MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
|
|
|
|
static struct platform_driver i2c_mux_reg_driver = {
|
|
.probe = i2c_mux_reg_probe,
|
|
.remove = i2c_mux_reg_remove,
|
|
.driver = {
|
|
.name = "i2c-mux-reg",
|
|
},
|
|
};
|
|
|
|
module_platform_driver(i2c_mux_reg_driver);
|
|
|
|
MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
|
|
MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS("platform:i2c-mux-reg");
|