From patchwork Tue Nov 17 09:52:25 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 56765 Delivered-To: patch@linaro.org Received: by 10.112.155.196 with SMTP id vy4csp1829964lbb; Tue, 17 Nov 2015 01:55:17 -0800 (PST) X-Received: by 10.66.219.228 with SMTP id pr4mr60746747pac.99.1447754116993; Tue, 17 Nov 2015 01:55:16 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id w5si57035062pbt.148.2015.11.17.01.55.16; Tue, 17 Nov 2015 01:55:16 -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 S1753612AbbKQJzM (ORCPT + 28 others); Tue, 17 Nov 2015 04:55:12 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:33284 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753479AbbKQJwk (ORCPT ); Tue, 17 Nov 2015 04:52:40 -0500 Received: by wmec201 with SMTP id c201so218305763wme.0 for ; Tue, 17 Nov 2015 01:52:39 -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=fwOTXV5xPKhTtKN7zViWTVGhZwfd7JnDnvPM1vify/J0JbrNHuwaxXj6U27RmFkgSQ yuwppl74McyLRB1qyheRugNroWW4LlPdfxIcBTokZ4SdlFDHoxm9DEmGFNPyoJX4sW6z GQESi0YOPiMKrAsPOZDHydkZUEw/+hJZsoSzh6ZqPvRTE0wHPT/TejZxQoehufE1rjb+ 0GdepjaKSa/nhKordS/VpbDUZtBIzP8PyD4No8E6xP9HXa7OXQcc2VoYWod0F0rZvxf5 GkN+uk8AA9L8TaxbXwApv2nAEp+TR0MC4qWnDeUrAFD9BPLRO8xVl+hxvjpMI934DNLv 6EVA== 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=kRpWq7ATUgmFpXf5V2e+fyyWHMF7oIlwTANZjfJAF4LSpaJYv7nFuY9WNDQ96c8vll Tv3gMGeiwEgkgMnZEzfa41U16NzvQwbJNDS13jobSGRZyXm744DpPARAxM35o2jyT7t+ oktHOmmjKJAGZsH3M21XRyHmq+YlmXYlX63Q+kscCUltymium9W/JPHnLQ+dN9aW8hzV 6vfKJMyIbOY5MJ/ecdJxWMhosS+L+zjfX6cBR2HTDpUDrt8F+48zfJGswBflu9LyUl6A 6dWwsNiMsYkhv/iaXKn0UufqY8OHlLTUMXD86bdgqi6H7EX4fJayyhSzmHcWyyfkIi/c HX+g== X-Gm-Message-State: ALoCoQm9lBylh/HgKqLmajoTM/5nVMbMhylZm3srMlfsoMa5t8TdjnTHSikCIBDvvpSsH0dTEyFq X-Received: by 10.28.72.136 with SMTP id v130mr1479505wma.60.1447753958978; Tue, 17 Nov 2015 01:52:38 -0800 (PST) Received: from bgdev-debian.home ([90.63.244.31]) by smtp.gmail.com with ESMTPSA id bk7sm38993546wjb.25.2015.11.17.01.52.38 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 17 Nov 2015 01:52:38 -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: Tue, 17 Nov 2015 10:52:25 +0100 Message-Id: <1447753950-17213-5-git-send-email-bgolaszewski@baylibre.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1447753950-17213-1-git-send-email-bgolaszewski@baylibre.com> References: <1447753950-17213-1-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) {