From patchwork Sun Nov 8 01:00:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brad Campbell X-Patchwork-Id: 11889359 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 98AC814B4 for ; Sun, 8 Nov 2020 01:00:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 557792151B for ; Sun, 8 Nov 2020 01:00:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fnarfbargle.com header.i=@fnarfbargle.com header.b="VVD0PYnO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726043AbgKHBA3 (ORCPT ); Sat, 7 Nov 2020 20:00:29 -0500 Received: from ns3.fnarfbargle.com ([103.4.19.87]:41478 "EHLO ns3.fnarfbargle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725838AbgKHBA2 (ORCPT ); Sat, 7 Nov 2020 20:00:28 -0500 Received: from srv.home ([10.8.0.1] ident=heh18629) by ns3.fnarfbargle.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1kbZ3p-0001e1-T5; Sun, 08 Nov 2020 09:00:01 +0800 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fnarfbargle.com; s=mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=rnKrYeIxAT41Kb8JnzWq78NR23AV+A5CY1fGvJJT7vk=; b=VVD0PYnOD7uiu95EWfTQphrNsQ0Att6f4K/QcZqx8n1EsL0QL/0sejIdm+k202uW0jj5DGyUez0bpnPGGXsYfI06CZzJDWLP0kVw8ZUFdUsnT1HQeCs+c6watq4LJNX1j8oFgVa9Ld3cGHIxLVyRaJOsc1eKJdVty9SATq6nNbY=; Subject: [PATCH v3] applesmc: Re-work SMC comms To: Henrik Rydberg Cc: Arnd Bergmann , linux-hwmon@vger.kernel.org, "linux-kernel@vger.kernel.org" , hns@goldelico.com, Guenter Roeck , Andreas Kemnade , Jean Delvare References: <20200930105442.3f642f6c@aktux> <20201002002251.28462e64@aktux> <7543ef85-727d-96c3-947e-5b18e9e6c44d@roeck-us.net> <20201006090226.4275c824@kemnade.info> <68467f1b-cea1-47ea-a4d4-8319214b072a@fnarfbargle.com> <20201104142057.62493c12@aktux> <2436afef-99c6-c352-936d-567bf553388c@fnarfbargle.com> <7a085650-2399-08c0-3c4d-6cd1fa28a365@roeck-us.net> <10027199-5d31-93e7-9bd8-7baaebff8b71@roeck-us.net> <70331f82-35a1-50bd-685d-0b06061dd213@fnarfbargle.com> <3c72ccc3-4de1-b5d0-423d-7b8c80991254@fnarfbargle.com> <6d071547-10ee-ca92-ec8b-4b5069d04501@bitmath.org> <8e117844-d62a-bcb1-398d-c59cc0d4b878@fnarfbargle.com> <9109d059-d9cb-7464-edba-3f42aa78ce92@bitmath.org> <5310c0ab-0f80-1f9e-8807-066223edae13@bitmath.org> From: Brad Campbell Message-ID: <57057d07-d3a0-8713-8365-7b12ca222bae@fnarfbargle.com> Date: Sun, 8 Nov 2020 12:00:03 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 In-Reply-To: <5310c0ab-0f80-1f9e-8807-066223edae13@bitmath.org> Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org G'day Henrik, I noticed you'd also loosened up the requirement for SMC_STATUS_BUSY in read_smc(). I assume that causes problems on the early Macbook. This is revised on the one sent earlier. If you could test this on your Air1,1 it'd be appreciated. Commit fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") introduced an issue whereby communication with the SMC became unreliable with write errors like : [ 120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40 [ 120.378621] applesmc: LKSB: write data fail [ 120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40 [ 120.512787] applesmc: LKSB: write data fail The original code appeared to be timing sensitive and was not reliable with the timing changes in the aforementioned commit. This patch re-factors the SMC communication to remove the timing dependencies and restore function with the changes previously committed. Tested on : MacbookAir6,2 MacBookPro11,1 iMac12,2 Fixes: fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") Reported-by: Andreas Kemnade Tested-by: Andreas Kemnade # MacBookAir6,2 Acked-by: Arnd Bergmann Signed-off-by: Brad Campbell Signed-off-by: Henrik Rydberg Reported-by: Andreas Kemnade Tested-by: Andreas Kemnade # MacBookAir6,2 Acked-by: Arnd Bergmann Signed-off-by: Brad Campbell Signed-off-by: Henrik Rydberg --- Changelog : v1 : Inital attempt v2 : Address logic and coding style v3 : Removed some debug hangover. Added tested-by. Modifications for MacBookAir1,1 diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c index a18887990f4a..3e968abb37aa 100644 --- a/drivers/hwmon/applesmc.c +++ b/drivers/hwmon/applesmc.c @@ -32,6 +32,7 @@ #include #include #include +#include /* data port used by Apple SMC */ #define APPLESMC_DATA_PORT 0x300 @@ -42,6 +43,11 @@ #define APPLESMC_MAX_DATA_LENGTH 32 +/* Apple SMC status bits */ +#define SMC_STATUS_AWAITING_DATA BIT(0) /* SMC has data waiting */ +#define SMC_STATUS_IB_CLOSED BIT(1) /* Will ignore any input */ +#define SMC_STATUS_BUSY BIT(2) /* Command in progress */ + /* wait up to 128 ms for a status change. */ #define APPLESMC_MIN_WAIT 0x0010 #define APPLESMC_RETRY_WAIT 0x0100 @@ -151,65 +157,73 @@ static unsigned int key_at_index; static struct workqueue_struct *applesmc_led_wq; /* - * wait_read - Wait for a byte to appear on SMC port. Callers must - * hold applesmc_lock. + * Wait for specific status bits with a mask on the SMC + * Used before and after writes, and before reads */ -static int wait_read(void) + +static int wait_status(u8 val, u8 mask) { unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC; u8 status; int us; + udelay(APPLESMC_MIN_WAIT); for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { - usleep_range(us, us * 16); status = inb(APPLESMC_CMD_PORT); - /* read: wait for smc to settle */ - if (status & 0x01) + if ((status & mask) == val) return 0; /* timeout: give up */ if (time_after(jiffies, end)) break; + usleep_range(us, us * 16); } - - pr_warn("wait_read() fail: 0x%02x\n", status); return -EIO; } /* - * send_byte - Write to SMC port, retrying when necessary. Callers + * send_byte_data - Write to SMC data port. Callers * must hold applesmc_lock. + * Parameter skip must be true on the last write of any + * command or it'll time out. */ -static int send_byte(u8 cmd, u16 port) + +static int send_byte_data(u8 cmd, u16 port, bool skip) { - u8 status; - int us; - unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC; + int ret; + ret = wait_status(SMC_STATUS_BUSY, SMC_STATUS_BUSY | SMC_STATUS_IB_CLOSED); + if (ret) + return ret; outb(cmd, port); - for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { - usleep_range(us, us * 16); - status = inb(APPLESMC_CMD_PORT); - /* write: wait for smc to settle */ - if (status & 0x02) - continue; - /* ready: cmd accepted, return */ - if (status & 0x04) - return 0; - /* timeout: give up */ - if (time_after(jiffies, end)) - break; - /* busy: long wait and resend */ - udelay(APPLESMC_RETRY_WAIT); - outb(cmd, port); - } + return wait_status(skip ? 0 : SMC_STATUS_BUSY, SMC_STATUS_BUSY); +} - pr_warn("send_byte(0x%02x, 0x%04x) fail: 0x%02x\n", cmd, port, status); - return -EIO; +static int send_byte(u8 cmd, u16 port) +{ + return send_byte_data(cmd, port, false); } +/* + * send_command - Write a command to the SMC. Callers must hold applesmc_lock. + * If SMC is in undefined state, any new command write resets the state machine. + */ + static int send_command(u8 cmd) { - return send_byte(cmd, APPLESMC_CMD_PORT); + int ret; + int i; + + for (i = 0; i < 16; i++) { + ret = wait_status(0, SMC_STATUS_IB_CLOSED); + if (ret) + return ret; + + outb(cmd, APPLESMC_CMD_PORT); + ret = wait_status(SMC_STATUS_BUSY, SMC_STATUS_BUSY); + if (!ret) + return ret; + } + return -EIO; } static int send_argument(const char *key) @@ -239,7 +253,8 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) } for (i = 0; i < len; i++) { - if (wait_read()) { + if (wait_status(SMC_STATUS_AWAITING_DATA, + SMC_STATUS_AWAITING_DATA | SMC_STATUS_IB_CLOSED)) { pr_warn("%.4s: read data[%d] fail\n", key, i); return -EIO; } @@ -250,7 +265,7 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) for (i = 0; i < 16; i++) { udelay(APPLESMC_MIN_WAIT); status = inb(APPLESMC_CMD_PORT); - if (!(status & 0x01)) + if (!(status & SMC_STATUS_AWAITING_DATA)) break; data = inb(APPLESMC_DATA_PORT); } @@ -275,7 +290,7 @@ static int write_smc(u8 cmd, const char *key, const u8 *buffer, u8 len) } for (i = 0; i < len; i++) { - if (send_byte(buffer[i], APPLESMC_DATA_PORT)) { + if (send_byte_data(buffer[i], APPLESMC_DATA_PORT, i == len - 1)) { pr_warn("%s: write data fail\n", key); return -EIO; }