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dm: sandbox: i2c: Add a new 'emulation parent' uclass

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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>
This commit is contained in:
Simon Glass 2018-11-18 08:14:33 -07:00
parent 25cbb47090
commit b7c25b11b6
3 changed files with 99 additions and 0 deletions
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77
drivers/i2c/i2c-emul-uclass.c
View file

@ -6,8 +6,85 @@
#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,
};

1
include/dm/uclass-id.h
View file

@ -21,6 +21,7 @@ enum uclass_id {
UCLASS_TEST_DUMMY,
UCLASS_SPI_EMUL, /* sandbox SPI device emulator */
UCLASS_I2C_EMUL, /* sandbox I2C device emulator */
UCLASS_I2C_EMUL_PARENT, /* parent for I2C device emulators */
UCLASS_PCI_EMUL, /* sandbox PCI device emulator */
UCLASS_USB_EMUL, /* sandbox USB bus device emulator */
UCLASS_AXI_EMUL, /* sandbox AXI bus device emulator */

21
include/i2c.h
View file

@ -536,6 +536,27 @@ int i2c_chip_ofdata_to_platdata(struct udevice *dev, struct dm_i2c_chip *chip);
*/
void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs);
/**
* i2c_emul_find() - Find an emulator for an i2c sandbox device
*
* This looks at the device's 'emul' phandle
*
* @dev: Device to find an emulator for
* @emulp: Returns the associated emulator, if found *
* @return 0 if OK, -ENOENT or -ENODEV if not found
*/
int i2c_emul_find(struct udevice *dev, struct udevice **emulp);
/**
* i2c_emul_get_device() - Find the device being emulated
*
* Given an emulator this returns the associated device
*
* @emul: Emulator for the device
* @return device that @emul is emulating
*/
struct udevice *i2c_emul_get_device(struct udevice *emul);
#ifndef CONFIG_DM_I2C
/*