u-boot/drivers/i2c/cros_ec_ldo.c
Simon Glass f48eaf01b2 cros_ec: Support the LDO access method used by spring
Add a driver to support the special LDO access used by spring. This is a
custom method in the cros_ec protocol - it does not use an I2C
pass-through.

There are two implementation choices:

1. Write a special LDO driver which can talk across the EC. Duplicate all
the logic from TPS65090 for retrying when the LDO fails to come up.

2. Write a special I2C bus driver which pretends to be a TPS65090 and
transfers reads and writes using the LDO message.

Either is distasteful. The latter method is chosen since it results in less
code duplication and a fairly simple (30-line) implementation of the core
logic.

The crosec 'ldo' subcommand could be removed (since i2c md/mw will work
instead) but is retained as a convenience.

Signed-off-by: Simon Glass <sjg@chromium.org>
2015-08-05 21:06:11 -06:00

77 lines
1.7 KiB
C

/*
* Copyright (c) 2015 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <cros_ec.h>
#include <errno.h>
#include <i2c.h>
#include <power/tps65090.h>
static int cros_ec_ldo_set_bus_speed(struct udevice *dev, unsigned int speed)
{
return 0;
}
static int cros_ec_ldo_xfer(struct udevice *dev, struct i2c_msg *msg,
int nmsgs)
{
bool is_read = nmsgs > 1;
int fet_id, ret;
/*
* Look for reads and writes of the LDO registers. In either case the
* first message is a write with the register number as the first byte.
*/
if (!nmsgs || !msg->len || (msg->flags & I2C_M_RD)) {
debug("%s: Invalid message\n", __func__);
goto err;
}
fet_id = msg->buf[0] - REG_FET_BASE;
if (fet_id < 1 || fet_id > MAX_FET_NUM) {
debug("%s: Invalid FET %d\n", __func__, fet_id);
goto err;
}
if (is_read) {
uint8_t state;
ret = cros_ec_get_ldo(dev->parent, fet_id, &state);
if (!ret)
msg[1].buf[0] = state ?
FET_CTRL_ENFET | FET_CTRL_PGFET : 0;
} else {
bool on = msg->buf[1] & FET_CTRL_ENFET;
ret = cros_ec_set_ldo(dev->parent, fet_id, on);
}
return ret;
err:
/* Indicate that the message is unimplemented */
return -ENOSYS;
}
static const struct dm_i2c_ops cros_ec_i2c_ops = {
.xfer = cros_ec_ldo_xfer,
.set_bus_speed = cros_ec_ldo_set_bus_speed,
};
static const struct udevice_id cros_ec_i2c_ids[] = {
{ .compatible = "google,cros-ec-ldo-tunnel" },
{ }
};
U_BOOT_DRIVER(cros_ec_ldo) = {
.name = "cros_ec_ldo_tunnel",
.id = UCLASS_I2C,
.of_match = cros_ec_i2c_ids,
.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
.ops = &cros_ec_i2c_ops,
};