From patchwork Thu Sep 20 16:14:23 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 972520 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-i2c-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=sang-engineering.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 42GMJ15KhTz9sBq for ; Fri, 21 Sep 2018 02:14:41 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730646AbeITV6t (ORCPT ); Thu, 20 Sep 2018 17:58:49 -0400 Received: from sauhun.de ([88.99.104.3]:60980 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728096AbeITV6t (ORCPT ); Thu, 20 Sep 2018 17:58:49 -0400 Received: from localhost (i577B999D.versanet.de [87.123.153.157]) by pokefinder.org (Postfix) with ESMTPSA id 76A4C2E35A8; Thu, 20 Sep 2018 18:14:34 +0200 (CEST) From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, Stefan Lengfeld , preid@electromag.com.au, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Keerthy , Tero Kristo , Grygorii Strashko , Andy Shevchenko , Wolfram Sang Subject: [RFC PATCH 4/4] i2c: core: introduce master_xfer_irqless callback Date: Thu, 20 Sep 2018 18:14:23 +0200 Message-Id: <20180920161423.13990-5-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180920161423.13990-1-wsa+renesas@sang-engineering.com> References: <20180920161423.13990-1-wsa+renesas@sang-engineering.com> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org We had the request to access devices very late when interrupts are not available anymore multiple times now. Mostly to prepare shutdown or reboot. Allow adapters to specify a specific callback for this case. Note that we fall back to the generic master_xfer callback if this new irqless one is not present. This is intentional to preserve the previous behaviour and avoid regressions. Because there are drivers not using interrupts or because it might have worked "accidently" before. Signed-off-by: Wolfram Sang Acked-by: Peter Rosin --- drivers/i2c/i2c-core-base.c | 6 +++++- include/linux/i2c.h | 10 +++++++--- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 904b4d2ebefa..f827446c3089 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -1887,7 +1887,11 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) /* Retry automatically on arbitration loss */ orig_jiffies = jiffies; for (ret = 0, try = 0; try <= adap->retries; try++) { - ret = adap->algo->master_xfer(adap, msgs, num); + if ((in_atomic() || irqs_disabled()) && adap->algo->master_xfer_irqless) + ret = adap->algo->master_xfer_irqless(adap, msgs, num); + else + ret = adap->algo->master_xfer(adap, msgs, num); + if (ret != -EAGAIN) break; if (time_after(jiffies, orig_jiffies + adap->timeout)) diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 65b4eaed1d96..11e615123bd0 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -498,6 +498,8 @@ i2c_register_board_info(int busnum, struct i2c_board_info const *info, * @master_xfer: Issue a set of i2c transactions to the given I2C adapter * defined by the msgs array, with num messages available to transfer via * the adapter specified by adap. + * @master_xfer_irqless: same as master_xfer. Yet, not using any interrupts + * so e.g. PMICs can be accessed very late before shutdown * @smbus_xfer: Issue smbus transactions to the given I2C adapter. If this * is not present, then the bus layer will try and convert the SMBus calls * into I2C transfers instead. @@ -511,9 +513,9 @@ i2c_register_board_info(int busnum, struct i2c_board_info const *info, * be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584 * to name two of the most common. * - * The return codes from the @master_xfer field should indicate the type of - * error code that occurred during the transfer, as documented in the kernel - * Documentation file Documentation/i2c/fault-codes. + * The return codes from the @master_xfer{_irqless} field should indicate the + * type of error code that occurred during the transfer, as documented in the + * Kernel Documentation file Documentation/i2c/fault-codes. */ struct i2c_algorithm { /* If an adapter algorithm can't do I2C-level access, set master_xfer @@ -524,6 +526,8 @@ struct i2c_algorithm { processed, or a negative value on error */ int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs, int num); + int (*master_xfer_irqless)(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num); int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data);