From patchwork Thu Nov 26 22:59:10 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 549246 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 409DB1402D2 for ; Fri, 27 Nov 2015 09:59:44 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753504AbbKZW7l (ORCPT ); Thu, 26 Nov 2015 17:59:41 -0500 Received: from sauhun.de ([89.238.76.85]:36519 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752947AbbKZW7X (ORCPT ); Thu, 26 Nov 2015 17:59:23 -0500 Received: from p4fe258bf.dip0.t-ipconnect.de ([79.226.88.191]:40124 helo=localhost) by pokefinder.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1a25VY-0001Hl-Nv; Thu, 26 Nov 2015 23:59:21 +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 Subject: [RFC 2/9] i2c: add generic routine to parse DT timing information Date: Thu, 26 Nov 2015 23:59:10 +0100 Message-Id: <1448578757-12613-3-git-send-email-wsa@the-dreams.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1448578757-12613-1-git-send-email-wsa@the-dreams.de> References: <1448578757-12613-1-git-send-email-wsa@the-dreams.de> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org From: Wolfram Sang Inspired from the i2c-rk3x driver, thanks guys! FIXME: add documentation Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core.c | 34 ++++++++++++++++++++++++++++++++++ include/linux/i2c.h | 15 +++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 040af5cc8143f1..7543fec4f65b61 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1438,6 +1438,40 @@ static void of_i2c_register_devices(struct i2c_adapter *adap) } } +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) && use_defaults) + t->bus_freq = 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 <= 100000) + t->scl_rise_ns = 1000; + else if (t->bus_freq <= 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 <= 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..ca28c104ac5fb6 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -413,6 +413,15 @@ struct i2c_algorithm { #endif }; +/* FIXME: Add docs */ +struct i2c_timings { + u32 bus_freq; + 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 @@ -644,6 +653,8 @@ 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 +671,10 @@ 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 */