From patchwork Thu Dec 3 15:51:32 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 7761411 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 15B3F9F30B for ; Thu, 3 Dec 2015 15:51:57 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BCE912047B for ; Thu, 3 Dec 2015 15:51:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4709220461 for ; Thu, 3 Dec 2015 15:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760645AbbLCPvx (ORCPT ); Thu, 3 Dec 2015 10:51:53 -0500 Received: from sauhun.de ([89.238.76.85]:33419 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752412AbbLCPvv (ORCPT ); Thu, 3 Dec 2015 10:51:51 -0500 Received: from p4fe25b0c.dip0.t-ipconnect.de ([79.226.91.12]:55007 helo=localhost) by pokefinder.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1a4WAf-00028R-QX; Thu, 03 Dec 2015 16:51:50 +0100 From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-sh@vger.kernel.org, Magnus Damm , Simon Horman , Laurent Pinchart , Geert Uytterhoeven , Wolfram Sang , Yoshihiro Shimoda , linux-rockchip@lists.infradead.org, Mika Westerberg , Andy Shevchenko , Jarkko Nikula Subject: [PATCH 2/9] i2c: add generic routine to parse DT for timing information Date: Thu, 3 Dec 2015 16:51:32 +0100 Message-Id: <1449157899-6572-3-git-send-email-wsa@the-dreams.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1449157899-6572-1-git-send-email-wsa@the-dreams.de> References: <1449157899-6572-1-git-send-email-wsa@the-dreams.de> Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Wolfram Sang Inspired from the i2c-rk3x driver (thanks guys!) but refactored and extended. See built-in docs for further information. Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/i2c.h | 22 ++++++++++++++++++++++ 2 files changed, 72 insertions(+) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index ba8eb087f22465..5c269dd51b2de7 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1438,6 +1438,56 @@ static void of_i2c_register_devices(struct i2c_adapter *adap) } } +/** + * of_i2c_parse_timings - get I2C related timing parameters from DT + * @node: The DT node to scan for I2C timing properties + * @t: the i2c_timings struct to be filled with values + * @use_defaults: bool to use sane defaults derived from the I2C specification + * when properties are not found, otherwise use 0 + * + * Scan the node pointer for the generic I2C DT properties describing timing + * parameters for the signal and fill the given struct with the results. If a + * property was not found and use_defaults was true, then maximum timings are + * assumed which are derived from the I2C specification. If use_defaults is not + * used, the result will be 0, so drivers can apply their own defaults later. + * The latter is mainly intended for avoiding regressions of existing drivers + * which want to switch to this function. New drivers almost always should use + * the defaults. + */ +void of_i2c_parse_timings(struct device_node *node, struct i2c_timings *t, bool use_defaults) +{ + memset(t, 0, sizeof(*t)); + + if (of_property_read_u32(node, "clock-frequency", &t->bus_freq_hz) && use_defaults) + t->bus_freq_hz = 100000; + + /* + * Read rise and fall time from device tree. If not available, use + * the default maximum timing from the specification. + */ + if (of_property_read_u32(node, "i2c-scl-rising-time-ns", &t->scl_rise_ns) && use_defaults) { + if (t->bus_freq_hz <= 100000) + t->scl_rise_ns = 1000; + else if (t->bus_freq_hz <= 400000) + t->scl_rise_ns = 300; + else + t->scl_rise_ns = 120; + } + + if (of_property_read_u32(node, "i2c-scl-falling-time-ns", &t->scl_fall_ns) && use_defaults) { + if (t->bus_freq_hz <= 400000) + t->scl_fall_ns = 300; + else + t->scl_fall_ns = 120; + } + + of_property_read_u32(node, "i2c-scl-internal-delay-ns", &t->scl_int_delay_ns); + + if (of_property_read_u32(node, "i2c-sda-falling-time-ns", &t->sda_fall_ns) && use_defaults) + t->sda_fall_ns = t->scl_fall_ns; +} +EXPORT_SYMBOL_GPL(of_i2c_parse_timings); + static int of_dev_node_match(struct device *dev, void *data) { return dev->of_node == data; diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 768063baafbf5e..c3f53666df117e 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -414,6 +414,22 @@ struct i2c_algorithm { }; /** + * struct i2c_timings - I2C timing information + * @bus_freq_hz: the bus frequency in Hz + * @scl_rise_ns: time SCL signal takes to rise in ns; t(r) in the I2C specification + * @scl_fall_ns: time SCL signal takes to fall in ns; t(f) in the I2C specification + * @scl_int_delay_ns: time IP core additionally needs to setup SCL in ns + * @sda_fall_ns: time SDA signal takes to fall in ns; t(f) in the I2C specification + */ +struct i2c_timings { + u32 bus_freq_hz; + u32 scl_rise_ns; + u32 scl_fall_ns; + u32 scl_int_delay_ns; + u32 sda_fall_ns; +}; + +/** * struct i2c_bus_recovery_info - I2C bus recovery information * @recover_bus: Recover routine. Either pass driver's recover_bus() routine, or * i2c_generic_scl_recovery() or i2c_generic_gpio_recovery(). @@ -644,6 +660,8 @@ extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node) /* must call i2c_put_adapter() when done with returned i2c_adapter device */ struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node); + +void of_i2c_parse_timings(struct device_node *node, struct i2c_timings *t, bool use_defaults); #else static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node) @@ -660,6 +678,10 @@ static inline struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node { return NULL; } + +static inline void of_i2c_parse_timings(struct device_node *node, struct i2c_timings *t, bool use_defaults) +{ +} #endif /* CONFIG_OF */ #endif /* _LINUX_I2C_H */