From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755532Ab2LLWFV (ORCPT ); Wed, 12 Dec 2012 17:05:21 -0500 Received: from mail-vc0-f201.google.com ([209.85.220.201]:59391 "EHLO mail-vc0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755407Ab2LLWFT (ORCPT ); Wed, 12 Dec 2012 17:05:19 -0500 X-Greylist: delayed 1806 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Dec 2012 17:05:18 EST From: Simon Glass To: LKML Cc: Samuel Ortiz , Simon Glass , Che-Liang Chiou Subject: [PATCH 3/5] mfd: Add ChromeOS EC I2C driver Date: Wed, 12 Dec 2012 13:33:46 -0800 Message-Id: <1355348028-19017-4-git-send-email-sjg@chromium.org> X-Mailer: git-send-email 1.7.7.3 In-Reply-To: <1355348028-19017-1-git-send-email-sjg@chromium.org> References: <1355348028-19017-1-git-send-email-sjg@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This uses an I2C bus to talk to the ChromeOS EC. The protocol is defined by the EC and is fairly simple, with a length byte, checksum, command byte and version byte (to permit easy creation of new commands). Signed-off-by: Simon Glass Signed-off-by: Che-Liang Chiou --- drivers/mfd/Kconfig | 10 ++ drivers/mfd/Makefile | 1 + drivers/mfd/cros_ec_i2c.c | 262 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 273 insertions(+), 0 deletions(-) create mode 100644 drivers/mfd/cros_ec_i2c.c diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig index 6983eb4..9351614 100644 --- a/drivers/mfd/Kconfig +++ b/drivers/mfd/Kconfig @@ -29,6 +29,16 @@ config MFD_CROS_EC You also ned to enable the driver for the bus you are using. The protocol for talking to the EC is defined by the bus driver. +config MFD_CROS_EC_I2C + tristate "ChromeOS Embedded Controller (I2C)" + depends on MFD_CROS_EC && I2C + + help + If you say here, you get support for talking to the ChromeOS EC + through an I2C bus. This uses a simple byte-level protocol with + a checksum. Failing accesses will be retried three times to + improve reliability. + config MFD_88PM800 tristate "Support Marvell 88PM800" depends on I2C=y && GENERIC_HARDIRQS diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile index 5a9c9f6..603912e 100644 --- a/drivers/mfd/Makefile +++ b/drivers/mfd/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_MFD_88PM805) += 88pm805.o 88pm80x.o obj-$(CONFIG_MFD_SM501) += sm501.o obj-$(CONFIG_MFD_ASIC3) += asic3.o tmio_core.o obj-$(CONFIG_MFD_CROS_EC) += cros_ec.o +obj-$(CONFIG_MFD_CROS_EC_I2C) += cros_ec_i2c.o rtsx_pci-objs := rtsx_pcr.o rts5209.o rts5229.o rtl8411.o obj-$(CONFIG_MFD_RTSX_PCI) += rtsx_pci.o diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c new file mode 100644 index 0000000..6b112ad --- /dev/null +++ b/drivers/mfd/cros_ec_i2c.c @@ -0,0 +1,262 @@ +/* + * ChromeOS EC multi-function device (I2C) + * + * Copyright (C) 2012 Google, Inc + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + + +/* Since I2C can be unreliable, we retry commands */ +#define COMMAND_MAX_TRIES 3 + +static inline struct cros_ec_device *to_ec_dev(struct device *dev) +{ + struct i2c_client *client = to_i2c_client(dev); + + return i2c_get_clientdata(client); +} + +static int cros_ec_command_xfer_noretry(struct cros_ec_device *ec_dev, + struct cros_ec_msg *msg) +{ + struct i2c_client *client = ec_dev->priv; + int ret = -ENOMEM; + int i; + int packet_len; + u8 *out_buf = NULL; + u8 *in_buf = NULL; + u8 sum; + struct i2c_msg i2c_msg[2]; + + i2c_msg[0].addr = client->addr; + i2c_msg[0].flags = 0; + i2c_msg[1].addr = client->addr; + i2c_msg[1].flags = I2C_M_RD; + + /* + * allocate larger packet (one byte for checksum, one byte for + * length, and one for result code) + */ + packet_len = msg->in_len + 3; + in_buf = kzalloc(packet_len, GFP_KERNEL); + if (!in_buf) + goto done; + i2c_msg[1].len = packet_len; + i2c_msg[1].buf = (char *)in_buf; + + /* + * allocate larger packet (one byte for checksum, one for + * command code, one for length, and one for command version) + */ + packet_len = msg->out_len + 4; + out_buf = kzalloc(packet_len, GFP_KERNEL); + if (!out_buf) + goto done; + i2c_msg[0].len = packet_len; + i2c_msg[0].buf = (char *)out_buf; + + out_buf[0] = EC_CMD_VERSION0 + msg->version; + out_buf[1] = msg->cmd; + out_buf[2] = msg->out_len; + + /* copy message payload and compute checksum */ + sum = out_buf[0] + out_buf[1] + out_buf[2]; + for (i = 0; i < msg->out_len; i++) { + out_buf[3 + i] = msg->out_buf[i]; + sum += out_buf[3 + i]; + } + out_buf[3 + msg->out_len] = sum; + + /* send command to EC and read answer */ + ret = i2c_transfer(client->adapter, i2c_msg, 2); + if (ret < 0) { + dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret); + goto done; + } else if (ret != 2) { + dev_err(ec_dev->dev, "failed to get response: %d\n", ret); + ret = -EIO; + goto done; + } + + /* check response error code */ + if (i2c_msg[1].buf[0]) { + dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n", + msg->cmd, i2c_msg[1].buf[0]); + ret = -EINVAL; + goto done; + } + + /* copy response packet payload and compute checksum */ + sum = in_buf[0] + in_buf[1]; + for (i = 0; i < msg->in_len; i++) { + msg->in_buf[i] = in_buf[2 + i]; + sum += in_buf[2 + i]; + } +#ifdef DEBUG + dev_dbg(ec_dev->dev, "packet: "); + for (i = 0; i < i2c_msg[1].len; i++) + dev_cont(ec_dev->dev, " %02x", in_buf[i]); + dev_cont(ec_dev->dev, ", sum = %02x\n", sum); +#endif + if (sum != in_buf[2 + msg->in_len]) { + dev_err(ec_dev->dev, "bad packet checksum\n"); + ret = -EBADMSG; + goto done; + } + + ret = 0; + done: + kfree(in_buf); + kfree(out_buf); + return ret; +} + +static int cros_ec_command_xfer(struct cros_ec_device *ec_dev, + struct cros_ec_msg *msg) +{ + int tries; + int ret; + /* + * Try the command a few times in case there are transmission errors. + * It is possible that this is overkill, but we don't completely trust + * i2c. + */ + for (tries = 0; tries < COMMAND_MAX_TRIES; tries++) { + ret = cros_ec_command_xfer_noretry(ec_dev, msg); + if (ret >= 0) + return ret; + } + dev_err(ec_dev->dev, "ec_command failed with %d (%d tries)\n", + ret, tries); + return ret; +} + +static const char *cros_ec_get_name(struct cros_ec_device *ec_dev) +{ + struct i2c_client *client = ec_dev->priv; + + return client->name; +} + +static const char *cros_ec_get_phys_name(struct cros_ec_device *ec_dev) +{ + struct i2c_client *client = ec_dev->priv; + + return client->adapter->name; +} + +static struct device *cros_ec_get_parent(struct cros_ec_device *ec_dev) +{ + struct i2c_client *client = ec_dev->priv; + + return &client->dev; +} + +static int __devinit cros_ec_probe_i2c(struct i2c_client *client, + const struct i2c_device_id *dev_id) +{ + struct device *dev = &client->dev; + struct cros_ec_device *ec_dev = NULL; + int err; + + if (dev->of_node && !of_device_is_available(dev->of_node)) { + dev_warn(dev, "Device disabled by device tree\n"); + return -ENODEV; + } + + ec_dev = cros_ec_alloc("I2C"); + if (!ec_dev) { + err = -ENOMEM; + dev_err(dev, "cannot create cros_ec\n"); + goto fail; + } + + i2c_set_clientdata(client, ec_dev); + ec_dev->dev = dev; + ec_dev->priv = client; + ec_dev->irq = client->irq; + ec_dev->command_xfer = cros_ec_command_xfer; + ec_dev->get_name = cros_ec_get_name; + ec_dev->get_phys_name = cros_ec_get_phys_name; + ec_dev->get_parent = cros_ec_get_parent; + + err = cros_ec_register(ec_dev); + if (err) { + dev_err(dev, "cannot register EC\n"); + goto fail_register; + } + + return 0; +fail_register: + cros_ec_free(ec_dev); +fail: + return err; +} + +static int __devexit cros_ec_remove_i2c(struct i2c_client *client) +{ + struct cros_ec_device *ec_dev = i2c_get_clientdata(client); + + cros_ec_remove(ec_dev); + cros_ec_free(ec_dev); + + return 0; +} + +#ifdef CONFIG_PM_SLEEP +static int cros_ec_i2c_suspend(struct device *dev) +{ + struct cros_ec_device *ec_dev = to_ec_dev(dev); + + return cros_ec_suspend(ec_dev); +} + +static int cros_ec_i2c_resume(struct device *dev) +{ + struct cros_ec_device *ec_dev = to_ec_dev(dev); + + return cros_ec_resume(ec_dev); +} +#endif + +static SIMPLE_DEV_PM_OPS(cros_ec_i2c_pm_ops, cros_ec_i2c_suspend, + cros_ec_i2c_resume); + +static const struct i2c_device_id cros_ec_i2c_id[] = { + { "cros-ec-i2c", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id); + +static struct i2c_driver cros_ec_driver = { + .driver = { + .name = "cros-ec-i2c", + .owner = THIS_MODULE, + .pm = &cros_ec_i2c_pm_ops, + }, + .probe = cros_ec_probe_i2c, + .remove = cros_ec_remove_i2c, + .id_table = cros_ec_i2c_id, +}; + +module_i2c_driver(cros_ec_driver); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("ChromeOS EC multi function device"); -- 1.7.7.3