diff options
author | Nick Crews <ncrews@chromium.org> | 2019-02-08 17:37:17 -0700 |
---|---|---|
committer | Enric Balletbo i Serra <enric.balletbo@collabora.com> | 2019-02-21 21:35:59 +0100 |
commit | 7b3d4f44abf0e7a1ba762c8a9c99a8b39ee0c8b1 (patch) | |
tree | 59ed497376f624fad1530a06870f43d86cabce33 /drivers | |
parent | 6b7cb2227d4d833aaccb3e98214015f2162d5bb0 (diff) |
platform/chrome: Add new driver for Wilco EC
This EC is an incompatible variant of the typical Chrome OS embedded
controller. It uses the same low-level communication and a similar
protocol with some significant differences. The EC firmware does
not support the same mailbox commands so it is not registered as a
cros_ec device type. This commit exports the wilco_ec_mailbox()
function so that other modules can use it to communicate with the EC.
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
[Fix the sparse warning: symbol 'wilco_ec_transfer' was not declared]
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
[Fix Kconfig dependencies for wilco_ec]
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/platform/chrome/Kconfig | 2 | ||||
-rw-r--r-- | drivers/platform/chrome/Makefile | 2 | ||||
-rw-r--r-- | drivers/platform/chrome/wilco_ec/Kconfig | 10 | ||||
-rw-r--r-- | drivers/platform/chrome/wilco_ec/Makefile | 4 | ||||
-rw-r--r-- | drivers/platform/chrome/wilco_ec/core.c | 104 | ||||
-rw-r--r-- | drivers/platform/chrome/wilco_ec/mailbox.c | 237 |
6 files changed, 359 insertions, 0 deletions
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig index 5e2fde5ff63d..9186d81a51cc 100644 --- a/drivers/platform/chrome/Kconfig +++ b/drivers/platform/chrome/Kconfig @@ -152,4 +152,6 @@ config CROS_EC_SYSFS To compile this driver as a module, choose M here: the module will be called cros_ec_sysfs. +source "drivers/platform/chrome/wilco_ec/Kconfig" + endif # CHROMEOS_PLATFORMS diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile index fdbee501931b..1e2f0029b597 100644 --- a/drivers/platform/chrome/Makefile +++ b/drivers/platform/chrome/Makefile @@ -14,3 +14,5 @@ obj-$(CONFIG_CROS_EC_LIGHTBAR) += cros_ec_lightbar.o obj-$(CONFIG_CROS_EC_VBC) += cros_ec_vbc.o obj-$(CONFIG_CROS_EC_DEBUGFS) += cros_ec_debugfs.o obj-$(CONFIG_CROS_EC_SYSFS) += cros_ec_sysfs.o + +obj-$(CONFIG_WILCO_EC) += wilco_ec/ diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig new file mode 100644 index 000000000000..c6bc4e8f3062 --- /dev/null +++ b/drivers/platform/chrome/wilco_ec/Kconfig @@ -0,0 +1,10 @@ +config WILCO_EC + tristate "ChromeOS Wilco Embedded Controller" + depends on ACPI && X86 && CROS_EC_LPC_MEC + help + If you say Y here, you get support for talking to the ChromeOS + Wilco EC over an eSPI bus. This uses a simple byte-level protocol + with a checksum. + + To compile this driver as a module, choose M here: the + module will be called wilco_ec. diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile new file mode 100644 index 000000000000..03b32301dc61 --- /dev/null +++ b/drivers/platform/chrome/wilco_ec/Makefile @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0 + +wilco_ec-objs := core.o mailbox.o +obj-$(CONFIG_WILCO_EC) += wilco_ec.o diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c new file mode 100644 index 000000000000..20ecc580d108 --- /dev/null +++ b/drivers/platform/chrome/wilco_ec/core.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Core driver for Wilco Embedded Controller + * + * Copyright 2018 Google LLC + * + * This is the entry point for the drivers that control the Wilco EC. + * This driver is responsible for several tasks: + * - Initialize the register interface that is used by wilco_ec_mailbox() + * - Create a platform device which is picked up by the debugfs driver + * - Create a platform device which is picked up by the RTC driver + */ + +#include <linux/acpi.h> +#include <linux/device.h> +#include <linux/ioport.h> +#include <linux/module.h> +#include <linux/platform_data/wilco-ec.h> +#include <linux/platform_device.h> + +#include "../cros_ec_lpc_mec.h" + +#define DRV_NAME "wilco-ec" + +static struct resource *wilco_get_resource(struct platform_device *pdev, + int index) +{ + struct device *dev = &pdev->dev; + struct resource *res; + + res = platform_get_resource(pdev, IORESOURCE_IO, index); + if (!res) { + dev_dbg(dev, "Couldn't find IO resource %d\n", index); + return res; + } + + return devm_request_region(dev, res->start, resource_size(res), + dev_name(dev)); +} + +static int wilco_ec_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct wilco_ec_device *ec; + + ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL); + if (!ec) + return -ENOMEM; + + platform_set_drvdata(pdev, ec); + ec->dev = dev; + mutex_init(&ec->mailbox_lock); + + /* Largest data buffer size requirement is extended data response */ + ec->data_size = sizeof(struct wilco_ec_response) + + EC_MAILBOX_DATA_SIZE_EXTENDED; + ec->data_buffer = devm_kzalloc(dev, ec->data_size, GFP_KERNEL); + if (!ec->data_buffer) + return -ENOMEM; + + /* Prepare access to IO regions provided by ACPI */ + ec->io_data = wilco_get_resource(pdev, 0); /* Host Data */ + ec->io_command = wilco_get_resource(pdev, 1); /* Host Command */ + ec->io_packet = wilco_get_resource(pdev, 2); /* MEC EMI */ + if (!ec->io_data || !ec->io_command || !ec->io_packet) + return -ENODEV; + + /* Initialize cros_ec register interface for communication */ + cros_ec_lpc_mec_init(ec->io_packet->start, + ec->io_packet->start + EC_MAILBOX_DATA_SIZE); + + return 0; +} + +static int wilco_ec_remove(struct platform_device *pdev) +{ + /* Teardown cros_ec interface */ + cros_ec_lpc_mec_destroy(); + + return 0; +} + +static const struct acpi_device_id wilco_ec_acpi_device_ids[] = { + { "GOOG000C", 0 }, + { } +}; +MODULE_DEVICE_TABLE(acpi, wilco_ec_acpi_device_ids); + +static struct platform_driver wilco_ec_driver = { + .driver = { + .name = DRV_NAME, + .acpi_match_table = wilco_ec_acpi_device_ids, + }, + .probe = wilco_ec_probe, + .remove = wilco_ec_remove, +}; + +module_platform_driver(wilco_ec_driver); + +MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>"); +MODULE_AUTHOR("Duncan Laurie <dlaurie@chromium.org>"); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("ChromeOS Wilco Embedded Controller driver"); +MODULE_ALIAS("platform:" DRV_NAME); diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c new file mode 100644 index 000000000000..f6ff29a11f1a --- /dev/null +++ b/drivers/platform/chrome/wilco_ec/mailbox.c @@ -0,0 +1,237 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Mailbox interface for Wilco Embedded Controller + * + * Copyright 2018 Google LLC + * + * The Wilco EC is similar to a typical ChromeOS embedded controller. + * It uses the same MEC based low-level communication and a similar + * protocol, but with some important differences. The EC firmware does + * not support the same mailbox commands so it is not registered as a + * cros_ec device type. + * + * Most messages follow a standard format, but there are some exceptions + * and an interface is provided to do direct/raw transactions that do not + * make assumptions about byte placement. + */ + +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/io.h> +#include <linux/platform_data/wilco-ec.h> +#include <linux/platform_device.h> + +#include "../cros_ec_lpc_mec.h" + +/* Version of mailbox interface */ +#define EC_MAILBOX_VERSION 0 + +/* Command to start mailbox transaction */ +#define EC_MAILBOX_START_COMMAND 0xda + +/* Version of EC protocol */ +#define EC_MAILBOX_PROTO_VERSION 3 + +/* Number of header bytes to be counted as data bytes */ +#define EC_MAILBOX_DATA_EXTRA 2 + +/* Maximum timeout */ +#define EC_MAILBOX_TIMEOUT HZ + +/* EC response flags */ +#define EC_CMDR_DATA BIT(0) /* Data ready for host to read */ +#define EC_CMDR_PENDING BIT(1) /* Write pending to EC */ +#define EC_CMDR_BUSY BIT(2) /* EC is busy processing a command */ +#define EC_CMDR_CMD BIT(3) /* Last host write was a command */ + +/** + * wilco_ec_response_timed_out() - Wait for EC response. + * @ec: EC device. + * + * Return: true if EC timed out, false if EC did not time out. + */ +static bool wilco_ec_response_timed_out(struct wilco_ec_device *ec) +{ + unsigned long timeout = jiffies + EC_MAILBOX_TIMEOUT; + + do { + if (!(inb(ec->io_command->start) & + (EC_CMDR_PENDING | EC_CMDR_BUSY))) + return false; + usleep_range(100, 200); + } while (time_before(jiffies, timeout)); + + return true; +} + +/** + * wilco_ec_checksum() - Compute 8-bit checksum over data range. + * @data: Data to checksum. + * @size: Number of bytes to checksum. + * + * Return: 8-bit checksum of provided data. + */ +static u8 wilco_ec_checksum(const void *data, size_t size) +{ + u8 *data_bytes = (u8 *)data; + u8 checksum = 0; + size_t i; + + for (i = 0; i < size; i++) + checksum += data_bytes[i]; + + return checksum; +} + +/** + * wilco_ec_prepare() - Prepare the request structure for the EC. + * @msg: EC message with request information. + * @rq: EC request structure to fill. + */ +static void wilco_ec_prepare(struct wilco_ec_message *msg, + struct wilco_ec_request *rq) +{ + memset(rq, 0, sizeof(*rq)); + + /* Handle messages without trimming bytes from the request */ + if (msg->request_size && msg->flags & WILCO_EC_FLAG_RAW_REQUEST) { + rq->reserved_raw = *(u8 *)msg->request_data; + msg->request_size--; + memmove(msg->request_data, msg->request_data + 1, + msg->request_size); + } + + /* Fill in request packet */ + rq->struct_version = EC_MAILBOX_PROTO_VERSION; + rq->mailbox_id = msg->type; + rq->mailbox_version = EC_MAILBOX_VERSION; + rq->data_size = msg->request_size + EC_MAILBOX_DATA_EXTRA; + rq->command = msg->command; + + /* Checksum header and data */ + rq->checksum = wilco_ec_checksum(rq, sizeof(*rq)); + rq->checksum += wilco_ec_checksum(msg->request_data, msg->request_size); + rq->checksum = -rq->checksum; +} + +/** + * wilco_ec_transfer() - Perform actual data transfer. + * @ec: EC device. + * @msg: EC message data for request and response. + * @rq: Filled in request structure + * + * Context: ec->mailbox_lock should be held while using this function. + * Return: number of bytes received or negative error code on failure. + */ +static int wilco_ec_transfer(struct wilco_ec_device *ec, + struct wilco_ec_message *msg, + struct wilco_ec_request *rq) +{ + struct wilco_ec_response *rs; + u8 checksum; + u8 flag; + size_t size; + + /* Write request header, then data */ + cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE, 0, sizeof(*rq), (u8 *)rq); + cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE, sizeof(*rq), msg->request_size, + msg->request_data); + + /* Start the command */ + outb(EC_MAILBOX_START_COMMAND, ec->io_command->start); + + /* For some commands (eg shutdown) the EC will not respond, that's OK */ + if (msg->flags & WILCO_EC_FLAG_NO_RESPONSE) { + dev_dbg(ec->dev, "EC does not respond to this command\n"); + return 0; + } + + /* Wait for it to complete */ + if (wilco_ec_response_timed_out(ec)) { + dev_dbg(ec->dev, "response timed out\n"); + return -ETIMEDOUT; + } + + /* Check result */ + flag = inb(ec->io_data->start); + if (flag) { + dev_dbg(ec->dev, "bad response: 0x%02x\n", flag); + return -EIO; + } + + if (msg->flags & WILCO_EC_FLAG_EXTENDED_DATA) + size = EC_MAILBOX_DATA_SIZE_EXTENDED; + else + size = EC_MAILBOX_DATA_SIZE; + + /* Read back response */ + rs = ec->data_buffer; + checksum = cros_ec_lpc_io_bytes_mec(MEC_IO_READ, 0, + sizeof(*rs) + size, (u8 *)rs); + if (checksum) { + dev_dbg(ec->dev, "bad packet checksum 0x%02x\n", rs->checksum); + return -EBADMSG; + } + + /* Check that the EC reported success */ + msg->result = rs->result; + if (msg->result) { + dev_dbg(ec->dev, "bad response: 0x%02x\n", msg->result); + return -EBADMSG; + } + + /* Check the returned data size, skipping the header */ + if (rs->data_size != size) { + dev_dbg(ec->dev, "unexpected packet size (%u != %zu)", + rs->data_size, size); + return -EMSGSIZE; + } + + /* Skip 1 response data byte unless specified */ + size = (msg->flags & WILCO_EC_FLAG_RAW_RESPONSE) ? 0 : 1; + if ((ssize_t) rs->data_size - size < msg->response_size) { + dev_dbg(ec->dev, "response data too short (%zd < %zu)", + (ssize_t) rs->data_size - size, msg->response_size); + return -EMSGSIZE; + } + + /* Ignore response data bytes as requested */ + memcpy(msg->response_data, rs->data + size, msg->response_size); + + /* Return actual amount of data received */ + return msg->response_size; +} + +/** + * wilco_ec_mailbox() - Send EC request and receive EC response. + * @ec: EC device. + * @msg: EC message data for request and response. + * + * On entry msg->type, msg->flags, msg->command, msg->request_size, + * msg->response_size, and msg->request_data should all be filled in. + * + * On exit msg->result and msg->response_data will be filled. + * + * Return: number of bytes received or negative error code on failure. + */ +int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg) +{ + struct wilco_ec_request *rq; + int ret; + + dev_dbg(ec->dev, "cmd=%02x type=%04x flags=%02x rslen=%zu rqlen=%zu\n", + msg->command, msg->type, msg->flags, msg->response_size, + msg->request_size); + + /* Prepare request packet */ + rq = ec->data_buffer; + wilco_ec_prepare(msg, rq); + + mutex_lock(&ec->mailbox_lock); + ret = wilco_ec_transfer(ec, msg, rq); + mutex_unlock(&ec->mailbox_lock); + + return ret; + +} +EXPORT_SYMBOL_GPL(wilco_ec_mailbox); |