From patchwork Thu Mar 24 16:19:37 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 64407 Delivered-To: patch@linaro.org Received: by 10.112.199.169 with SMTP id jl9csp756947lbc; Thu, 24 Mar 2016 09:21:15 -0700 (PDT) X-Received: by 10.98.72.218 with SMTP id q87mr14159030pfi.117.1458836466763; Thu, 24 Mar 2016 09:21:06 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id s28si13089334pfi.238.2016.03.24.09.21.06; Thu, 24 Mar 2016 09:21:06 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-i2c-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@baylibre-com.20150623.gappssmtp.com; spf=pass (google.com: best guess record for domain of linux-i2c-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-i2c-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757037AbcCXQVD (ORCPT + 1 other); Thu, 24 Mar 2016 12:21:03 -0400 Received: from mail-wm0-f54.google.com ([74.125.82.54]:37020 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756729AbcCXQTy (ORCPT ); Thu, 24 Mar 2016 12:19:54 -0400 Received: by mail-wm0-f54.google.com with SMTP id p65so73383541wmp.0 for ; Thu, 24 Mar 2016 09:19:54 -0700 (PDT) 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=9IXGO0joUV6RbP5gKGnFScswun2cd+dbcnM+z5of2Og=; b=YxYbrrd6uOKJNrWvFKjMBv+pCgGCOczIejsNSpG5xCE2hPZHDDpkJi1mmPX2DdVXlb u495CtBQ4LuC+ZJdOLe0Z9Q5XQv8GfDIaL8mkK6TKFALkLmtbl1udhy37ZDANhqFAjLe RR8o5bZIoEdmN94iLEzrQ34QrqZSDz+WKyMatTy7H9ko0CicyHF9xjqFnKuHIJNo70/d eykvQXxOZjnq+udrIgaeYkUnvhJdUuhtp8m4/aUMpLNnZEvJEK62njm2KKtI2Rw5WrRd 4lnbD0M67JOwGEJBqrYG7zXSFluA8hvLOCZGIfvKwN2q2szzAo0SsAa27h0Yzcic/fju TCCg== 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=9IXGO0joUV6RbP5gKGnFScswun2cd+dbcnM+z5of2Og=; b=amg3HFLKUzF6cCV5SwOYcybtDTkzVFe8vugWq71/59mAFhoOJFaqAMogjy+B2b+Szp 6vaOnR88SawxJCL6d57DQNiPVwM//utniou4k88OhA7+y5kfuVv3r6qMPw/Dvm3u15uL OkRNym7rxJqg+k7SiPKIS3EpzpTzoo6mxjJqvzkZlJZkD8bWFX6vtxcjC3/MzNqb5OlY jKzMMy6tlVQI/II8fJp03HG7UOAACDwgvEmA88TVWKkqYO+APQz2f6mhQDow4LIsy/+O UjGaPmzI5pzc0wOqo8AEtOTh/N76F+iJEUtwePec2949Tp9fP7MK0GcgmwW9xYXMlLsC MkOw== X-Gm-Message-State: AD7BkJLf8Bqheqvs7mH/A//P0mxr50zLyGT7CfmHU9r2po8cThkNfh9UoARkiza5YSURMoLA X-Received: by 10.28.91.83 with SMTP id p80mr35987377wmb.48.1458836393393; Thu, 24 Mar 2016 09:19:53 -0700 (PDT) Received: from localhost.localdomain ([90.63.244.31]) by smtp.gmail.com with ESMTPSA id k124sm8370718wmb.11.2016.03.24.09.19.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 24 Mar 2016 09:19:52 -0700 (PDT) From: Bartosz Golaszewski To: Wolfram Sang , linux-i2c , LKML Cc: Andrew Lunn , Bartosz Golaszewski Subject: [PATCH v2 07/13] eeprom: at24: support reading of the serial number Date: Thu, 24 Mar 2016 17:19:37 +0100 Message-Id: <1458836383-6668-8-git-send-email-bgolaszewski@baylibre.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1458836383-6668-1-git-send-email-bgolaszewski@baylibre.com> References: <1458836383-6668-1-git-send-email-bgolaszewski@baylibre.com> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@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 | 59 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index bc5be1e..fda5c56 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -159,6 +159,65 @@ static struct i2c_client *at24_translate_offset(struct at24_data *at24, return at24->client[i]; } +static ssize_t __attribute__((unused)) +at24cs_serial_read(struct at24_data *at24, + char *buf, loff_t off, size_t count) +{ + unsigned long timeout, read_time; + struct i2c_client *client; + unsigned int offset = off; + struct i2c_msg msg[2]; + u8 addrbuf[2]; + int status; + + client = at24_translate_offset(at24, &offset); + + 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; + + timeout = jiffies + msecs_to_jiffies(write_timeout); + do { + read_time = jiffies; + status = i2c_transfer(client->adapter, msg, 2); + if (status == 2) + return count; + + usleep_range(1000, 1500); + } while (time_before(read_time, timeout)); + + return -ETIMEDOUT; +} + static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf, unsigned offset, size_t count) {