From patchwork Thu Feb 28 11:01:40 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jean Delvare X-Patchwork-Id: 223884 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id CFCA92C0296 for ; Thu, 28 Feb 2013 22:02:03 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752852Ab3B1LBx (ORCPT ); Thu, 28 Feb 2013 06:01:53 -0500 Received: from zoneX.GCU-Squad.org ([194.213.125.0]:6649 "EHLO services.gcu-squad.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752918Ab3B1LBu (ORCPT ); Thu, 28 Feb 2013 06:01:50 -0500 Received: from jdelvare.pck.nerim.net ([62.212.121.182] helo=endymion.delvare) by services.gcu-squad.org (GCU Mailer Daemon) with esmtpsa id 1UB1FB-0008KW-Th (TLSv1:AES128-SHA:128) (envelope-from ) ; Thu, 28 Feb 2013 12:01:46 +0100 Date: Thu, 28 Feb 2013 12:01:40 +0100 From: Jean Delvare To: Linux I2C Cc: Bo Shen , Karol Lewandowski , Jean-Christophe PLAGNIOL-VILLARD Subject: [PATCH] i2c-gpio: Add support for deferred probing Message-ID: <20130228120140.127ebb91@endymion.delvare> X-Mailer: Claws Mail 3.7.10 (GTK+ 2.24.7; x86_64-suse-linux-gnu) Mime-Version: 1.0 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org GPIOs may not be available immediately when i2c-gpio looks for them. Implement support for deferred probing so that probing can be attempted again later when GPIO pins are finally available. Signed-off-by: Jean Delvare Cc: Haavard Skinnemoen Tested-by: Bo Shen --- A little more changes were needed than I initially thought, because we want to check the pins before we allocate memory. Otherwise we would have a possibly large number of memory allocation and freeing cycles until GPIO pins are finally available. I wrote this quite some time ago already, but I do not have any system to test it. I would appreciate if one or more users of the i2c-gpio driver could give it a try and confirm it works as intended, or at least doesn't introduce any regression. Thanks. drivers/i2c/busses/i2c-gpio.c | 75 ++++++++++++++++++++++++++++-------------- 1 file changed, 50 insertions(+), 25 deletions(-) --- linux-3.8-rc2.orig/drivers/i2c/busses/i2c-gpio.c 2013-01-09 22:26:30.031060312 +0100 +++ linux-3.8-rc2/drivers/i2c/busses/i2c-gpio.c 2013-01-09 22:32:59.950308645 +0100 @@ -85,23 +85,29 @@ static int i2c_gpio_getscl(void *data) return gpio_get_value(pdata->scl_pin); } -static int of_i2c_gpio_probe(struct device_node *np, - struct i2c_gpio_platform_data *pdata) +static int of_i2c_gpio_get_pins(struct device_node *np, + unsigned int *sda_pin, unsigned int *scl_pin) { - u32 reg; - if (of_gpio_count(np) < 2) return -ENODEV; - pdata->sda_pin = of_get_gpio(np, 0); - pdata->scl_pin = of_get_gpio(np, 1); + *sda_pin = of_get_gpio(np, 0); + *scl_pin = of_get_gpio(np, 1); - if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) { + if (!gpio_is_valid(*sda_pin) || !gpio_is_valid(*scl_pin)) { pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n", - np->full_name, pdata->sda_pin, pdata->scl_pin); + np->full_name, *sda_pin, *scl_pin); return -ENODEV; } + return 0; +} + +static void of_i2c_gpio_get_props(struct device_node *np, + struct i2c_gpio_platform_data *pdata) +{ + u32 reg; + of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay); if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®)) @@ -113,8 +119,6 @@ static int of_i2c_gpio_probe(struct devi of_property_read_bool(np, "i2c-gpio,scl-open-drain"); pdata->scl_is_output_only = of_property_read_bool(np, "i2c-gpio,scl-output-only"); - - return 0; } static int i2c_gpio_probe(struct platform_device *pdev) @@ -123,31 +127,52 @@ static int i2c_gpio_probe(struct platfor struct i2c_gpio_platform_data *pdata; struct i2c_algo_bit_data *bit_data; struct i2c_adapter *adap; + unsigned int sda_pin, scl_pin; int ret; - priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); - if (!priv) - return -ENOMEM; - adap = &priv->adap; - bit_data = &priv->bit_data; - pdata = &priv->pdata; - + /* First get the GPIO pins; if it fails, we'll defer the probe. */ if (pdev->dev.of_node) { - ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata); + ret = of_i2c_gpio_get_pins(pdev->dev.of_node, + &sda_pin, &scl_pin); if (ret) return ret; } else { if (!pdev->dev.platform_data) return -ENXIO; - memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata)); + pdata = pdev->dev.platform_data; + sda_pin = pdata->sda_pin; + scl_pin = pdata->scl_pin; } - ret = gpio_request(pdata->sda_pin, "sda"); - if (ret) + ret = gpio_request(sda_pin, "sda"); + if (ret) { + if (ret == -EINVAL) + ret = -EPROBE_DEFER; /* Try again later */ goto err_request_sda; - ret = gpio_request(pdata->scl_pin, "scl"); - if (ret) + } + ret = gpio_request(scl_pin, "scl"); + if (ret) { + if (ret == -EINVAL) + ret = -EPROBE_DEFER; /* Try again later */ goto err_request_scl; + } + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) { + ret = -ENOMEM; + goto err_add_bus; + } + adap = &priv->adap; + bit_data = &priv->bit_data; + pdata = &priv->pdata; + + if (pdev->dev.of_node) { + pdata->sda_pin = sda_pin; + pdata->scl_pin = scl_pin; + of_i2c_gpio_get_props(pdev->dev.of_node, pdata); + } else { + memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata)); + } if (pdata->sda_is_open_drain) { gpio_direction_output(pdata->sda_pin, 1); @@ -211,9 +236,9 @@ static int i2c_gpio_probe(struct platfor return 0; err_add_bus: - gpio_free(pdata->scl_pin); + gpio_free(scl_pin); err_request_scl: - gpio_free(pdata->sda_pin); + gpio_free(sda_pin); err_request_sda: return ret; }