From patchwork Wed Dec 2 10:25:21 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 57551 Delivered-To: patch@linaro.org Received: by 10.112.155.196 with SMTP id vy4csp2773017lbb; Wed, 2 Dec 2015 02:27:41 -0800 (PST) X-Received: by 10.98.68.80 with SMTP id r77mr3409103pfa.113.1449052061736; Wed, 02 Dec 2015 02:27:41 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 17si3797496pfo.238.2015.12.02.02.27.41; Wed, 02 Dec 2015 02:27:41 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dkim=neutral (body hash did not verify) header.i=@baylibre-com.20150623.gappssmtp.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757827AbbLBK1j (ORCPT + 28 others); Wed, 2 Dec 2015 05:27:39 -0500 Received: from mail-wm0-f41.google.com ([74.125.82.41]:35436 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755339AbbLBKZj (ORCPT ); Wed, 2 Dec 2015 05:25:39 -0500 Received: by wmuu63 with SMTP id u63so208404587wmu.0 for ; Wed, 02 Dec 2015 02:25:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=4r0R775uen0LQV69t0krZLBaQhYU9dUknMye6W9lSm0=; b=Oszgw6hA0ym3/G/1Gl9Zfp03f1od4OJPExeJcBq1gCtVSMfXjmkuLws/hPngWa5keY mKFKSuwjhH4PmejiCfxvXDkq0j1GfsY/vA+MkzQDhMmyUCZiyp9kaNDls0MNJghqX2gi T1j2ezQLveTFAhp8yGp8q1lKjnrEFSqdujeBpwdw13uE3NYznJjKH5Ga9j58ubh5NRdT kCP9rppXfoTeiXt0gAOfdB9y0P31a5Py1mNmNBBMuca0xGSt5K+iUIWO0JsHlmLp4Yjd aWEbS0Ti5LHr7wGtsTTg4FfQTchAxAjPaSFdT34idbNbr5kKoy3OnhJRDzmmjSpM7k3d mDtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=4r0R775uen0LQV69t0krZLBaQhYU9dUknMye6W9lSm0=; b=eSkV2b317so/1NLIehsvf+yYT1taubuAwrNJ3xoEf1XtHVwpHNPJnBQUuBmw+B0G5u a1ebdCNC1ZBOZbc1bEJKRblmYkO5kCASV3nfrE1rIwYF9wytQtv6NKehgEE+8KF3VgKi 0L5/loWIqK2Vj9FwB1c20KXOiaUEERQFthRjRGf+z/rl8teY074ORcSSDZVsBM3N5wLQ UyCSlGB8+velv2UiSKdhkV8LR+WrCK8iLEWn7oc8eAf5sv1zLME9WCTr77+PgYKE7K0A xG+zfZBbIhI/W458JPC39W2p/uSDDYpd5EaDIDOl/atzl8nEEKdpjn/qNIaw4vOADyvN BoYg== X-Gm-Message-State: ALoCoQmHPRKQIgyWpTJ2lr0cIoEe0D1JBU3AiKN+MtEK6hUKEFc3m5UtyTXXGzdLUH7ng9x/Tpwc X-Received: by 10.28.186.67 with SMTP id k64mr44432748wmf.56.1449051938678; Wed, 02 Dec 2015 02:25:38 -0800 (PST) Received: from bgdev-debian.home ([90.63.244.31]) by smtp.gmail.com with ESMTPSA id bg10sm2077707wjb.46.2015.12.02.02.25.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 02 Dec 2015 02:25:38 -0800 (PST) From: Bartosz Golaszewski To: Wolfram Sang Cc: linux-i2c , LKML , Bartosz Golaszewski Subject: [RESEND PATCH v2 4/9] eeprom: at24: support reading of the serial number Date: Wed, 2 Dec 2015 11:25:21 +0100 Message-Id: <1449051926-21918-5-git-send-email-bgolaszewski@baylibre.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1449051926-21918-1-git-send-email-bgolaszewski@baylibre.com> References: <1449051926-21918-1-git-send-email-bgolaszewski@baylibre.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The at24cs series EEPROM chips have an additional read-only memory area containing a factory pre-programmed serial number. In order to access it, one has to perform a dummy write before reading the serial number bytes. Add a function that allows to access the serial number. Signed-off-by: Bartosz Golaszewski --- drivers/misc/eeprom/at24.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index 08cc327..6182f47 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -163,6 +163,77 @@ static struct i2c_client *at24_translate_offset(struct at24_data *at24, return at24->client[i]; } +static int __attribute__((unused)) at24cs_eeprom_serial_read( + struct at24_data *at24, + char *buf, unsigned offset, + size_t count) +{ + unsigned long timeout, read_time; + struct i2c_client *client; + struct i2c_msg msg[2]; + u8 addrbuf[2]; + int status; + + mutex_lock(&at24->lock); + + client = at24->client[1]; + + memset(msg, 0, sizeof(msg)); + msg[0].addr = client->addr; + msg[0].buf = addrbuf; + + /* + * The address pointer of the device is shared between the regular + * EEPROM array and the serial number block. The dummy write (part of + * the sequential read protocol) ensures the address pointer is reset + * to the desired position. + */ + if (at24->chip.flags & AT24_FLAG_ADDR16) { + /* + * For 16 bit address pointers, the word address must contain + * a '10' sequence in bits 11 and 10 regardless of the + * intended position of the address pointer. + */ + addrbuf[0] = 0x08; + addrbuf[1] = offset; + msg[0].len = 2; + } else { + /* + * Otherwise the word address must begin with a '10' sequence, + * regardless of the intended address. + */ + addrbuf[0] = 0x80 + offset; + msg[0].len = 1; + } + + msg[1].addr = client->addr; + msg[1].flags = I2C_M_RD; + msg[1].buf = buf; + msg[1].len = count; + + /* + * Reads fail if the previous write didn't complete yet. We may + * loop a few times until this one succeeds, waiting at least + * long enough for one entire page write to work. + */ + timeout = jiffies + msecs_to_jiffies(write_timeout); + do { + read_time = jiffies; + status = i2c_transfer(client->adapter, msg, 2); + if (status == 2) { + mutex_unlock(&at24->lock); + return count; + } + + /* REVISIT: at HZ=100, this is sloooow */ + msleep(1); + } while (time_before(read_time, timeout)); + + mutex_unlock(&at24->lock); + + return -ETIMEDOUT; +} + static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf, unsigned offset, size_t count) {