From f48eaf01b2f7212987166aae970b895c7e215466 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Mon, 3 Aug 2015 08:19:24 -0600 Subject: 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 --- drivers/i2c/Kconfig | 13 ++++++++ drivers/i2c/Makefile | 1 + drivers/i2c/cros_ec_ldo.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 91 insertions(+) create mode 100644 drivers/i2c/cros_ec_ldo.c (limited to 'drivers/i2c') diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index e861b53686..9a62ddd9ca 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -29,6 +29,19 @@ config I2C_CROS_EC_TUNNEL I2C or LPC). Some Chromebooks use this when the hardware design does not allow direct access to the main PMIC from the AP. +config I2C_CROS_EC_LDO + bool "Provide access to LDOs on the Chrome OS EC" + depends on CROS_EC + ---help--- + On many Chromebooks the main PMIC is inaccessible to the AP. This is + often dealt with by using an I2C pass-through interface provided by + the EC. On some unfortunate models (e.g. Spring) the pass-through + is not available, and an LDO message is available instead. This + option enables a driver which provides very basic access to those + regulators, via the EC. We implement this as an I2C bus which + emulates just the TPS65090 messages we know about. This is done to + avoid duplicating the logic in the TPS65090 regulator driver for + enabling/disabling an LDO. config DM_I2C_GPIO bool "Enable Driver Model for software emulated I2C bus driver" diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index 7f01fce2e7..9b45248e2e 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_DM_I2C) += i2c-uclass.o obj-$(CONFIG_DM_I2C_COMPAT) += i2c-uclass-compat.o obj-$(CONFIG_DM_I2C_GPIO) += i2c-gpio.o obj-$(CONFIG_I2C_CROS_EC_TUNNEL) += cros_ec_tunnel.o +obj-$(CONFIG_I2C_CROS_EC_LDO) += cros_ec_ldo.o obj-$(CONFIG_SYS_I2C_ADI) += adi_i2c.o obj-$(CONFIG_I2C_MV) += mv_i2c.o diff --git a/drivers/i2c/cros_ec_ldo.c b/drivers/i2c/cros_ec_ldo.c new file mode 100644 index 0000000000..b817c61f1c --- /dev/null +++ b/drivers/i2c/cros_ec_ldo.c @@ -0,0 +1,77 @@ +/* + * Copyright (c) 2015 Google, Inc + * Written by Simon Glass + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include +#include +#include +#include +#include +#include + +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, +}; -- cgit v1.2.1