From patchwork Thu May 12 07:57:09 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Wu X-Patchwork-Id: 9077261 Return-Path: X-Original-To: patchwork-linux-arm@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 666159F372 for ; Thu, 12 May 2016 07:59:55 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 739E4201D3 for ; Thu, 12 May 2016 07:59:54 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6A97420155 for ; Thu, 12 May 2016 07:59:53 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1b0lV0-0002uw-1A; Thu, 12 May 2016 07:57:34 +0000 Received: from lucky1.263xmail.com ([211.157.147.133]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1b0lUw-0002ic-56; Thu, 12 May 2016 07:57:31 +0000 Received: from david.wu?rock-chips.com (unknown [192.168.167.78]) by lucky1.263xmail.com (Postfix) with SMTP id 38C4853DB6; Thu, 12 May 2016 15:57:06 +0800 (CST) X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.263.net (Postfix) with ESMTP id 7DEFE2D6AB; Thu, 12 May 2016 15:56:58 +0800 (CST) X-RL-SENDER: david.wu@rock-chips.com X-FST-TO: heiko@sntech.de X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: david.wu@rock-chips.com X-UNIQUE-TAG: <27e28797af9923264a850f4be5ea883e> X-ATTACHMENT-NUM: 0 X-SENDER: wdc@rock-chips.com X-DNS-TYPE: 0 Received: from localhost.localdomain (unknown [58.22.7.114]) by smtp.263.net (Postfix) whith ESMTP id 20976WXKA27; Thu, 12 May 2016 15:57:00 +0800 (CST) From: David Wu To: heiko@sntech.de, wsa@the-dreams.de Subject: [PATCH v9 5/8] i2c: rk3x: Move spec timing data to "static const" structs Date: Thu, 12 May 2016 15:57:09 +0800 Message-Id: <1463039829-8267-1-git-send-email-david.wu@rock-chips.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1463039586-8134-1-git-send-email-david.wu@rock-chips.com> References: <1463039586-8134-1-git-send-email-david.wu@rock-chips.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160512_005730_638151_5346986E X-CRM114-Status: GOOD ( 13.28 ) X-Spam-Score: -1.9 (-) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, huangtao@rock-chips.com, xjq@rock-chips.com, hl@rock-chips.com, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, devicetree@vger.kernel.org, linux-rockchip@lists.infradead.org, David Wu , dianders@chromium.org, linux-kernel@vger.kernel.org, cf@rock-chips.com, andy.shevchenko@gmail.com, robh+dt@kernel.org, linux-i2c@vger.kernel.org, galak@codeaurora.org, zyw@rock-chips.com, briannorris@google.com, davidriley@google.com, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable 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 The i2c timing specs are really just constant data. There's no reason to write code to init them, so move them out to structures. This not only is a cleaner solution but it will reduce code duplication when we introduce a new variant of rk3x_i2c_calc_divs() in a future patch. Signed-off-by: David Wu Suggested-by: Douglas Anderson Reviewed-by: Douglas Anderson --- Change in v9: - none Changes in v8: - add commit description. - remove the spec values that were not needed, then introduce the additional values in the rk3399 patch. drivers/i2c/busses/i2c-rk3x.c | 83 ++++++++++++++++++++++++++++--------------- 1 file changed, 55 insertions(+), 28 deletions(-) diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c index d7a871f..9791797 100644 --- a/drivers/i2c/busses/i2c-rk3x.c +++ b/drivers/i2c/busses/i2c-rk3x.c @@ -76,6 +76,34 @@ enum { #define DEFAULT_SCL_RATE (100 * 1000) /* Hz */ /** + * struct i2c_spec_values: + * @min_low_ns: min LOW period of the SCL clock + * @min_high_ns: min HIGH period of the SCL cloc + * @min_setup_start_ns: min set-up time for a repeated START conditio + * @max_data_hold_ns: max data hold time + */ +struct i2c_spec_values { + unsigned long min_low_ns; + unsigned long min_high_ns; + unsigned long min_setup_start_ns; + unsigned long max_data_hold_ns; +}; + +static const struct i2c_spec_values standard_mode_spec = { + .min_low_ns = 4700, + .min_high_ns = 4000, + .min_setup_start_ns = 4700, + .max_data_hold_ns = 3450, +}; + +static const struct i2c_spec_values fast_mode_spec = { + .min_low_ns = 1300, + .min_high_ns = 600, + .min_setup_start_ns = 600, + .max_data_hold_ns = 900, +}; + +/** * struct rk3x_i2c_calced_timings: * @div_low: Divider output for low * @div_high: Divider output for high @@ -460,6 +488,21 @@ out: } /** + * Get timing values of I2C specification + * + * @speed: Desired SCL frequency + * + * Returns: Matched i2c spec values. + */ +static const struct i2c_spec_values *rk3x_i2c_get_spec(unsigned int speed) +{ + if (speed <= 100000) + return &standard_mode_spec; + else + return &fast_mode_spec; +} + +/** * Calculate divider values for desired SCL frequency * * @clk_rate: I2C input clock rate @@ -474,10 +517,6 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, struct i2c_timings *t, struct rk3x_i2c_calced_timings *t_calc) { - unsigned long spec_min_low_ns, spec_min_high_ns; - unsigned long spec_setup_start, spec_max_data_hold_ns; - unsigned long data_hold_buffer_ns; - unsigned long min_low_ns, min_high_ns; unsigned long max_low_ns, min_total_ns; @@ -489,6 +528,8 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long min_div_for_hold, min_total_div; unsigned long extra_div, extra_low_div, ideal_low_div; + unsigned long data_hold_buffer_ns = 50; + const struct i2c_spec_values *spec; int ret = 0; /* Only support standard-mode and fast-mode */ @@ -511,22 +552,8 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, * This is because the i2c host on Rockchip holds the data line * for half the low time. */ - if (t->bus_freq_hz <= 100000) { - /* Standard-mode */ - spec_min_low_ns = 4700; - spec_setup_start = 4700; - spec_min_high_ns = 4000; - spec_max_data_hold_ns = 3450; - data_hold_buffer_ns = 50; - } else { - /* Fast-mode */ - spec_min_low_ns = 1300; - spec_setup_start = 600; - spec_min_high_ns = 600; - spec_max_data_hold_ns = 900; - data_hold_buffer_ns = 50; - } - min_high_ns = t->scl_rise_ns + spec_min_high_ns; + spec = rk3x_i2c_get_spec(t->bus_freq_hz); + min_high_ns = t->scl_rise_ns + spec->min_high_ns; /* * Timings for repeated start: @@ -536,14 +563,14 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, * We need to account for those rules in picking our "high" time so * we meet tSU;STA and tHD;STA times. */ - min_high_ns = max(min_high_ns, - DIV_ROUND_UP((t->scl_rise_ns + spec_setup_start) * 1000, 875)); - min_high_ns = max(min_high_ns, - DIV_ROUND_UP((t->scl_rise_ns + spec_setup_start + - t->sda_fall_ns + spec_min_high_ns), 2)); - - min_low_ns = t->scl_fall_ns + spec_min_low_ns; - max_low_ns = spec_max_data_hold_ns * 2 - data_hold_buffer_ns; + min_high_ns = max(min_high_ns, DIV_ROUND_UP( + (t->scl_rise_ns + spec->min_setup_start_ns) * 1000, 875)); + min_high_ns = max(min_high_ns, DIV_ROUND_UP( + (t->scl_rise_ns + spec->min_setup_start_ns + t->sda_fall_ns + + spec->min_high_ns), 2)); + + min_low_ns = t->scl_fall_ns + spec->min_low_ns; + max_low_ns = spec->max_data_hold_ns * 2 - data_hold_buffer_ns; min_total_ns = min_low_ns + min_high_ns; /* Adjust to avoid overflow */