mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-16 01:38:22 +00:00
b7c25b11b6
Sandbox i2c works using emulation drivers which are currently children of
the i2c device:
rtc_0: rtc@43 {
reg = <0x43>;
compatible = "sandbox-rtc";
emul {
compatible = "sandbox,i2c-rtc";
};
};
In this case the emulation device is attached to i2c bus on address 0x43
and provides the Real-Time-Clock (RTC) functionality.
However this is not ideal, since every device on an I2C bus has a child
device. This is only really the case for sandbox, but we want to avoid
special-case code for sandbox.
A better approach seems to be to add a separate node on the bus, an
'emulation parent'. This can be given a bogus address (such as 0xff) and
hides all the emulators away. Then we can use a phandle to point from the
device to the correct emualtor, and only on sandbox. The code to find an
emulator does not interfere with normal i2c operation.
Add a new UCLASS_I2C_EMUL_PARENT uclass which allows finding an emulator
given a bus, and finding a bus given an emulator. This will be used in a
follow-on patch.
Signed-off-by: Simon Glass <sjg@chromium.org>
90 lines
2.5 KiB
C
90 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* Copyright (c) 2014 Google, Inc
|
|
*/
|
|
|
|
#include <common.h>
|
|
#include <dm.h>
|
|
#include <i2c.h>
|
|
#include <dm/device-internal.h>
|
|
#include <dm/uclass-internal.h>
|
|
|
|
/*
|
|
* i2c emulation works using an 'emul' node at the bus level. Each device in
|
|
* that node is in the UCLASS_I2C_EMUL uclass, and emulates one i2c device. A
|
|
* pointer to the device it emulates is in the 'dev' property of the emul device
|
|
* uclass platdata (struct i2c_emul_platdata), put there by i2c_emul_find().
|
|
* When sandbox wants an emulator for a device, it calls i2c_emul_find() which
|
|
* searches for the emulator with the correct address. To find the device for an
|
|
* emulator, call i2c_emul_get_device().
|
|
*
|
|
* The 'emul' node is in the UCLASS_I2C_EMUL_PARENT uclass. We use a separate
|
|
* uclass so avoid having strange devices on the I2C bus.
|
|
*/
|
|
|
|
/**
|
|
* struct i2c_emul_uc_platdata - information about the emulator for this device
|
|
*
|
|
* This is used by devices in UCLASS_I2C_EMUL to record information about the
|
|
* device being emulated. It is accessible with dev_get_uclass_platdata()
|
|
*
|
|
* @dev: Device being emulated
|
|
*/
|
|
struct i2c_emul_uc_platdata {
|
|
struct udevice *dev;
|
|
};
|
|
|
|
struct udevice *i2c_emul_get_device(struct udevice *emul)
|
|
{
|
|
struct i2c_emul_uc_platdata *uc_plat = dev_get_uclass_platdata(emul);
|
|
|
|
return uc_plat->dev;
|
|
}
|
|
|
|
int i2c_emul_find(struct udevice *dev, struct udevice **emulp)
|
|
{
|
|
struct i2c_emul_uc_platdata *uc_plat;
|
|
struct udevice *emul;
|
|
int ret;
|
|
|
|
ret = uclass_find_device_by_phandle(UCLASS_I2C_EMUL, dev,
|
|
"sandbox,emul", &emul);
|
|
if (ret) {
|
|
log_err("No emulators for device '%s'\n", dev->name);
|
|
return ret;
|
|
}
|
|
uc_plat = dev_get_uclass_platdata(emul);
|
|
uc_plat->dev = dev;
|
|
*emulp = emul;
|
|
|
|
return device_probe(emul);
|
|
}
|
|
|
|
UCLASS_DRIVER(i2c_emul) = {
|
|
.id = UCLASS_I2C_EMUL,
|
|
.name = "i2c_emul",
|
|
.per_device_platdata_auto_alloc_size =
|
|
sizeof(struct i2c_emul_uc_platdata),
|
|
};
|
|
|
|
/*
|
|
* This uclass is a child of the i2c bus. Its platdata is not defined here so
|
|
* is defined by its parent, UCLASS_I2C, which uses struct dm_i2c_chip. See
|
|
* per_child_platdata_auto_alloc_size in UCLASS_DRIVER(i2c).
|
|
*/
|
|
UCLASS_DRIVER(i2c_emul_parent) = {
|
|
.id = UCLASS_I2C_EMUL_PARENT,
|
|
.name = "i2c_emul_parent",
|
|
.post_bind = dm_scan_fdt_dev,
|
|
};
|
|
|
|
static const struct udevice_id i2c_emul_parent_ids[] = {
|
|
{ .compatible = "sandbox,i2c-emul-parent" },
|
|
{ }
|
|
};
|
|
|
|
U_BOOT_DRIVER(i2c_emul_parent_drv) = {
|
|
.name = "i2c_emul_parent_drv",
|
|
.id = UCLASS_I2C_EMUL_PARENT,
|
|
.of_match = i2c_emul_parent_ids,
|
|
};
|