From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 491E9C10F06 for ; Wed, 3 Apr 2019 14:39:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10FF42084C for ; Wed, 3 Apr 2019 14:39:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726496AbfDCOjm (ORCPT ); Wed, 3 Apr 2019 10:39:42 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:50858 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726151AbfDCOjl (ORCPT ); Wed, 3 Apr 2019 10:39:41 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 414B62806B8 Subject: Re: [PATCH v3 1/2] platform/chrome: wilco_ec: Standardize mailbox interface To: Nick Crews , bleung@chromium.org, linux-leds@vger.kernel.org, jacek.anaszewski@gmail.com, pavel@ucw.cz Cc: linux-kernel@vger.kernel.org, dlaurie@chromium.org, sjg@google.com, groeck@google.com, dtor@google.com, Alessandro Zummo , Alexandre Belloni , linux-rtc@vger.kernel.org References: <20190403020519.211483-1-ncrews@chromium.org> From: Enric Balletbo i Serra Message-ID: Date: Wed, 3 Apr 2019 16:39:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190403020519.211483-1-ncrews@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nick, On 3/4/19 4:05, Nick Crews wrote: > The current API for the wilco EC mailbox interface is bad. > > It assumes that most messages sent to the EC follow a similar structure, > with a command byte in MBOX[0], followed by a junk byte, followed by > actual data. This doesn't happen in several cases, such as setting the > RTC time, using the raw debugfs interface, and reading or writing > properties such as the Peak Shift policy (this last to be submitted soon). > > Similarly for the response message from the EC, the current interface > assumes that the first byte of data is always 0, and the second byte > is unused. However, in both setting and getting the RTC time, in the > debugfs interface, and for reading and writing properties, this isn't > true. > > The current way to resolve this is to use WILCO_EC_FLAG_RAW* flags to > specify when and when not to skip these initial bytes in the sent and > received message. They are confusing and used so much that they are > normal, and not exceptions. In addition, the first byte of > response in the debugfs interface is still always skipped, which is > weird, since this raw interface should be giving the entire result. > > Additionally, sent messages assume the first byte is a command, and so > struct wilco_ec_message contains the "command" field. In setting or > getting properties however, the first byte is not a command, and so this > field has to be filled with a byte that isn't actually a command. This > is again inconsistent. > > wilco_ec_message contains a result field as well, copied from > wilco_ec_response->result. The message result field should be removed: > if the message fails, the cause is already logged, and the callers are > alerted. They will never care about the actual state of the result flag. > > These flags and different cases make the wilco_ec_transfer() function, > used in wilco_ec_mailbox(), really gross, dealing with a bunch of > different cases. It's difficult to figure out what it is doing. > > Finally, making these assumptions about the structure of a message make > it so that the messages do not correspond well with the specification > for the EC's mailbox interface. For instance, this interface > specification may say that MBOX[9] in the received message contains > some information, but the calling code needs to remember that the first > byte of response is always skipped, and because it didn't set the > RESPONSE_RAW flag, the next byte is also skipped, so this information > is actually contained within wilco_ec_message->response_data[7]. This > makes it difficult to maintain this code in the future. > > To fix these problems this patch standardizes the mailbox interface by: > - Removing the WILCO_EC_FLAG_RAW* flags > - Removing the command and reserved_raw bytes from wilco_ec_request > - Removing the mbox0 byte from wilco_ec_response > - Simplifying wilco_ec_transfer() because of these changes > - Gives the callers of wilco_ec_mailbox() the responsibility of exactly > and consistently defining the structure of the mailbox request and > response > - Removing command and result from wilco_ec_message. > > This results in the reduction of total code, and makes it much more > maintainable and understandable. > > Signed-off-by: Nick Crews > --- > drivers/platform/chrome/wilco_ec/debugfs.c | 43 ++++++++------- > drivers/platform/chrome/wilco_ec/mailbox.c | 53 ++++++++---------- > drivers/rtc/rtc-wilco-ec.c | 63 +++++++++++++--------- I'd like to see an ack from rtc maintainer before merging this. Cc'ing the RTC maintainers and the rtc mailing list. The patch looks good to me. I think that this can go all through the platform/chrome tree if the RTC maintainers are agree. > include/linux/platform_data/wilco-ec.h | 22 +------- > 4 files changed, 83 insertions(+), 98 deletions(-) > > diff --git a/drivers/platform/chrome/wilco_ec/debugfs.c b/drivers/platform/chrome/wilco_ec/debugfs.c > index c090db2cd5be..17c4c9068aaf 100644 > --- a/drivers/platform/chrome/wilco_ec/debugfs.c > +++ b/drivers/platform/chrome/wilco_ec/debugfs.c > @@ -10,25 +10,26 @@ > * by reading from raw. > * > * For writing: > - * Bytes 0-1 indicate the message type: > - * 00 F0 = Execute Legacy Command > - * 00 F2 = Read/Write NVRAM Property > - * Byte 2 provides the command code > - * Bytes 3+ consist of the data passed in the request > + * Bytes 0-1 indicate the message type, one of enum wilco_ec_msg_type > + * Byte 2+ consist of the data passed in the request, starting at MBOX[0] > * > - * When referencing the EC interface spec, byte 2 corresponds to MBOX[0], > - * byte 3 corresponds to MBOX[1], etc. > - * > - * At least three bytes are required, for the msg type and command, > - * with additional bytes optional for additional data. > + * At least three bytes are required for writing, two for the type and at > + * least a single byte of data. Only the first EC_MAILBOX_DATA_SIZE bytes > + * of MBOX will be used. > * > * Example: > * // Request EC info type 3 (EC firmware build date) > - * $ echo 00 f0 38 00 03 00 > raw > + * // Corresponds with sending type 0x00f0 with MBOX = [38, 00, 03, 00] > + * $ echo 00 f0 38 00 03 00 > /sys/kernel/debug/wilco_ec/raw > * // View the result. The decoded ASCII result "12/21/18" is > * // included after the raw hex. > - * $ cat raw > - * 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 .12/21/18.8... > + * // Corresponds with MBOX = [00, 00, 31, 32, 2f, 32, 31, ...] > + * $ cat /sys/kernel/debug/wilco_ec/raw > + * 00 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 ..12/21/18.8... > + * > + * Note that the first 32 bytes of the received MBOX[] will be printed, > + * even if some of the data is junk. It is up to you to know how many of > + * the first bytes of data are the actual response. > */ > > #include > @@ -136,18 +137,15 @@ static ssize_t raw_write(struct file *file, const char __user *user_buf, > ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE); > if (ret < 0) > return ret; > - /* Need at least two bytes for message type and one for command */ > + /* Need at least two bytes for message type and one byte of data */ > if (ret < 3) > return -EINVAL; > > - /* Clear response data buffer */ > - memset(debug_info->raw_data, '\0', EC_MAILBOX_DATA_SIZE_EXTENDED); > - > msg.type = request_data[0] << 8 | request_data[1]; > - msg.flags = WILCO_EC_FLAG_RAW; > - msg.command = request_data[2]; > - msg.request_data = ret > 3 ? request_data + 3 : 0; > - msg.request_size = ret - 3; > + msg.flags = 0; > + msg.request_data = request_data + 2; > + msg.request_size = ret - 2; > + memset(debug_info->raw_data, 0, sizeof(debug_info->raw_data)); > msg.response_data = debug_info->raw_data; > msg.response_size = EC_MAILBOX_DATA_SIZE; > > @@ -174,7 +172,8 @@ static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count, > fmt_len = hex_dump_to_buffer(debug_info->raw_data, > debug_info->response_size, > 16, 1, debug_info->formatted_data, > - FORMATTED_BUFFER_SIZE, true); > + sizeof(debug_info->formatted_data), > + true); > /* Only return response the first time it is read */ > debug_info->response_size = 0; > } > diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c > index 14355668ddfa..7fb58b487963 100644 > --- a/drivers/platform/chrome/wilco_ec/mailbox.c > +++ b/drivers/platform/chrome/wilco_ec/mailbox.c > @@ -92,21 +92,10 @@ 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; > + rq->data_size = msg->request_size; > > /* Checksum header and data */ > rq->checksum = wilco_ec_checksum(rq, sizeof(*rq)); > @@ -159,6 +148,12 @@ static int wilco_ec_transfer(struct wilco_ec_device *ec, > return -EIO; > } > > + /* > + * The EC always returns either EC_MAILBOX_DATA_SIZE or > + * EC_MAILBOX_DATA_SIZE_EXTENDED bytes of data, so we need to > + * calculate the checksum on **all** of this data, even if we > + * won't use all of it. > + */ > if (msg->flags & WILCO_EC_FLAG_EXTENDED_DATA) > size = EC_MAILBOX_DATA_SIZE_EXTENDED; > else > @@ -173,33 +168,26 @@ static int wilco_ec_transfer(struct wilco_ec_device *ec, > 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); > + if (rs->result) { > + dev_dbg(ec->dev, "EC reported failure: 0x%02x\n", rs->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); > + if (rs->data_size < msg->response_size) { > + dev_dbg(ec->dev, "EC didn't return enough data (%u < %zu)", > + rs->data_size, msg->response_size); > return -EMSGSIZE; > } > > - /* Ignore response data bytes as requested */ > - memcpy(msg->response_data, rs->data + size, msg->response_size); > + memcpy(msg->response_data, rs->data, msg->response_size); > > - /* Return actual amount of data received */ > - return msg->response_size; > + return rs->data_size; > } > > /** > @@ -207,10 +195,12 @@ static int wilco_ec_transfer(struct wilco_ec_device *ec, > * @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 entry msg->type, msg->request_size, and msg->request_data should all be > + * filled in. If desired, msg->flags can be set. > * > - * On exit msg->result and msg->response_data will be filled. > + * If a response is expected, msg->response_size should be set, and > + * msg->response_data should point to a buffer with enough space. On exit > + * msg->response_data will be filled. > * > * Return: number of bytes received or negative error code on failure. > */ > @@ -219,9 +209,8 @@ 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); > + dev_dbg(ec->dev, "type=%04x flags=%02x rslen=%zu rqlen=%zu\n", > + msg->type, msg->flags, msg->response_size, msg->request_size); > > mutex_lock(&ec->mailbox_lock); > /* Prepare request packet */ > diff --git a/drivers/rtc/rtc-wilco-ec.c b/drivers/rtc/rtc-wilco-ec.c > index e62bda0cb53e..8ad4c4e6d557 100644 > --- a/drivers/rtc/rtc-wilco-ec.c > +++ b/drivers/rtc/rtc-wilco-ec.c > @@ -21,8 +21,20 @@ > #define EC_CMOS_TOD_WRITE 0x02 > #define EC_CMOS_TOD_READ 0x08 > > +/* Message sent to the EC to request the current time. */ > +struct ec_rtc_read_request { > + u8 command; > + u8 reserved; > + u8 param; > +} __packed; Add and empty line, don't need to resend for this, I can fix myself when I merge. > +static struct ec_rtc_read_request read_rq = { > + .command = EC_COMMAND_CMOS, > + .param = EC_CMOS_TOD_READ, > +}; > + > /** > - * struct ec_rtc_read - Format of RTC returned by EC. > + * struct ec_rtc_read_response - Format of RTC returned by EC. > + * @reserved: Unused byte > * @second: Second value (0..59) > * @minute: Minute value (0..59) > * @hour: Hour value (0..23) > @@ -33,7 +45,8 @@ > * > * All values are presented in binary (not BCD). > */ > -struct ec_rtc_read { > +struct ec_rtc_read_response { > + u8 reserved; > u8 second; > u8 minute; > u8 hour; > @@ -44,8 +57,10 @@ struct ec_rtc_read { > } __packed; > > /** > - * struct ec_rtc_write - Format of RTC sent to the EC. > - * @param: EC_CMOS_TOD_WRITE > + * struct ec_rtc_write_request - Format of RTC sent to the EC. > + * @command: Always EC_COMMAND_CMOS > + * @reserved: Unused byte > + * @param: Always EC_CMOS_TOD_WRITE > * @century: Century value (full year / 100) > * @year: Year value (full year % 100) > * @month: Month value (1..12) > @@ -57,7 +72,9 @@ struct ec_rtc_read { > * > * All values are presented in BCD. > */ > -struct ec_rtc_write { > +struct ec_rtc_write_request { > + u8 command; > + u8 reserved; > u8 param; > u8 century; > u8 year; > @@ -72,19 +89,17 @@ struct ec_rtc_write { > static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) > { > struct wilco_ec_device *ec = dev_get_drvdata(dev->parent); > - u8 param = EC_CMOS_TOD_READ; > - struct ec_rtc_read rtc; > - struct wilco_ec_message msg = { > - .type = WILCO_EC_MSG_LEGACY, > - .flags = WILCO_EC_FLAG_RAW_RESPONSE, > - .command = EC_COMMAND_CMOS, > - .request_data = ¶m, > - .request_size = sizeof(param), > - .response_data = &rtc, > - .response_size = sizeof(rtc), > - }; > + struct ec_rtc_read_response rtc; > + struct wilco_ec_message msg; > int ret; > > + memset(&msg, 0, sizeof(msg)); > + msg.type = WILCO_EC_MSG_LEGACY; > + msg.request_data = &read_rq; > + msg.request_size = sizeof(read_rq); > + msg.response_data = &rtc; > + msg.response_size = sizeof(rtc); > + > ret = wilco_ec_mailbox(ec, &msg); > if (ret < 0) > return ret; > @@ -106,14 +121,8 @@ static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) > static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm) > { > struct wilco_ec_device *ec = dev_get_drvdata(dev->parent); > - struct ec_rtc_write rtc; > - struct wilco_ec_message msg = { > - .type = WILCO_EC_MSG_LEGACY, > - .flags = WILCO_EC_FLAG_RAW_RESPONSE, > - .command = EC_COMMAND_CMOS, > - .request_data = &rtc, > - .request_size = sizeof(rtc), > - }; > + struct ec_rtc_write_request rtc; > + struct wilco_ec_message msg; > int year = tm->tm_year + 1900; > /* > * Convert from 0=Sunday to 0=Saturday for the EC > @@ -123,6 +132,7 @@ static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm) > int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1; > int ret; > > + rtc.command = EC_COMMAND_CMOS; > rtc.param = EC_CMOS_TOD_WRITE; > rtc.century = bin2bcd(year / 100); > rtc.year = bin2bcd(year % 100); > @@ -133,6 +143,11 @@ static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm) > rtc.second = bin2bcd(tm->tm_sec); > rtc.weekday = bin2bcd(wday); > > + memset(&msg, 0, sizeof(msg)); > + msg.type = WILCO_EC_MSG_LEGACY; > + msg.request_data = &rtc; > + msg.request_size = sizeof(rtc); > + > ret = wilco_ec_mailbox(ec, &msg); > if (ret < 0) > return ret; > diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h > index 446473a46b88..1ff224793c99 100644 > --- a/include/linux/platform_data/wilco-ec.h > +++ b/include/linux/platform_data/wilco-ec.h > @@ -14,10 +14,6 @@ > /* Message flags for using the mailbox() interface */ > #define WILCO_EC_FLAG_NO_RESPONSE BIT(0) /* EC does not respond */ > #define WILCO_EC_FLAG_EXTENDED_DATA BIT(1) /* EC returns 256 data bytes */ > -#define WILCO_EC_FLAG_RAW_REQUEST BIT(2) /* Do not trim request data */ > -#define WILCO_EC_FLAG_RAW_RESPONSE BIT(3) /* Do not trim response data */ > -#define WILCO_EC_FLAG_RAW (WILCO_EC_FLAG_RAW_REQUEST | \ > - WILCO_EC_FLAG_RAW_RESPONSE) > > /* Normal commands have a maximum 32 bytes of data */ > #define EC_MAILBOX_DATA_SIZE 32 > @@ -56,10 +52,7 @@ struct wilco_ec_device { > * @mailbox_id: Mailbox identifier, specifies the command set. > * @mailbox_version: Mailbox interface version %EC_MAILBOX_VERSION > * @reserved: Set to zero. > - * @data_size: Length of request, data + last 2 bytes of the header. > - * @command: Mailbox command code, unique for each mailbox_id set. > - * @reserved_raw: Set to zero for most commands, but is used by > - * some command types and for raw commands. > + * @data_size: Length of following data. > */ > struct wilco_ec_request { > u8 struct_version; > @@ -68,8 +61,6 @@ struct wilco_ec_request { > u8 mailbox_version; > u8 reserved; > u16 data_size; > - u8 command; > - u8 reserved_raw; > } __packed; > > /** > @@ -79,8 +70,6 @@ struct wilco_ec_request { > * @result: Result code from the EC. Non-zero indicates an error. > * @data_size: Length of the response data buffer. > * @reserved: Set to zero. > - * @mbox0: EC returned data at offset 0 is unused (always 0) so this byte > - * is treated as part of the header instead of the data. > * @data: Response data buffer. Max size is %EC_MAILBOX_DATA_SIZE_EXTENDED. > */ > struct wilco_ec_response { > @@ -89,7 +78,6 @@ struct wilco_ec_response { > u16 result; > u16 data_size; > u8 reserved[2]; > - u8 mbox0; > u8 data[0]; > } __packed; > > @@ -111,21 +99,15 @@ enum wilco_ec_msg_type { > * struct wilco_ec_message - Request and response message. > * @type: Mailbox message type. > * @flags: Message flags, e.g. %WILCO_EC_FLAG_NO_RESPONSE. > - * @command: Mailbox command code. > - * @result: Result code from the EC. Non-zero indicates an error. > * @request_size: Number of bytes to send to the EC. > * @request_data: Buffer containing the request data. > - * @response_size: Number of bytes expected from the EC. > - * This is 32 by default and 256 if the flag > - * is set for %WILCO_EC_FLAG_EXTENDED_DATA > + * @response_size: Number of bytes to read from EC. > * @response_data: Buffer containing the response data, should be > * response_size bytes and allocated by caller. > */ > struct wilco_ec_message { > enum wilco_ec_msg_type type; > u8 flags; > - u8 command; > - u8 result; > size_t request_size; > void *request_data; > size_t response_size; >