From patchwork Mon Oct 3 20:06:14 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Noralf_Tr=C3=B8nnes?= X-Patchwork-Id: 9360919 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2590C607D6 for ; Mon, 3 Oct 2016 20:10:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0D90C2890B for ; Mon, 3 Oct 2016 20:10:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F3F4228A7D; Mon, 3 Oct 2016 20:10:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 649E42890B for ; Mon, 3 Oct 2016 20:10:02 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1br9XT-00031T-2d; Mon, 03 Oct 2016 20:08:39 +0000 Received: from smtp.domeneshop.no ([2a01:5b40:0:3005::1]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1br9W0-0001li-4A; Mon, 03 Oct 2016 20:07:13 +0000 Received: from 211.81-166-168.customer.lyse.net ([81.166.168.211]:36309 helo=localhost.localdomain) by smtp.domeneshop.no with esmtpsa (TLS1.1:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1br9Vb-0006Iz-Ma; Mon, 03 Oct 2016 22:06:43 +0200 From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= To: wsa@the-dreams.de, swarren@wwwdotorg.org, eric@anholt.net Subject: [PATCH v4 7/7] i2c: bcm2835: Add support for dynamic clock Date: Mon, 3 Oct 2016 22:06:14 +0200 Message-Id: <1475525174-28604-8-git-send-email-noralf@tronnes.org> X-Mailer: git-send-email 2.8.2 In-Reply-To: <1475525174-28604-1-git-send-email-noralf@tronnes.org> References: <1475525174-28604-1-git-send-email-noralf@tronnes.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161003_130708_474075_29213863 X-CRM114-Status: GOOD ( 13.71 ) 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: linux-rpi-kernel@lists.infradead.org, =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Support a dynamic clock by reading the frequency and setting the divisor in the transfer function instead of during probe. Signed-off-by: Noralf Trønnes Reviewed-by: Martin Sperl --- drivers/i2c/busses/i2c-bcm2835.c | 51 +++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 19 deletions(-) diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index d2085dd..c3436f6 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -58,6 +58,7 @@ struct bcm2835_i2c_dev { void __iomem *regs; struct clk *clk; int irq; + u32 bus_clk_rate; struct i2c_adapter adapter; struct completion completion; struct i2c_msg *curr_msg; @@ -78,6 +79,30 @@ static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) return readl(i2c_dev->regs + reg); } +static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev) +{ + u32 divider; + + divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), + i2c_dev->bus_clk_rate); + /* + * Per the datasheet, the register is always interpreted as an even + * number, by rounding down. In other words, the LSB is ignored. So, + * if the LSB is set, increment the divider to avoid any issue. + */ + if (divider & 1) + divider++; + if ((divider < BCM2835_I2C_CDIV_MIN) || + (divider > BCM2835_I2C_CDIV_MAX)) { + dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n"); + return -EINVAL; + } + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); + + return 0; +} + static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) { u32 val; @@ -224,7 +249,7 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], { struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); unsigned long time_left; - int i; + int i, ret; for (i = 0; i < (num - 1); i++) if (msgs[i].flags & I2C_M_RD) { @@ -233,6 +258,10 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], return -EOPNOTSUPP; } + ret = bcm2835_i2c_set_divider(i2c_dev); + if (ret) + return ret; + i2c_dev->curr_msg = msgs; i2c_dev->num_msgs = num; reinit_completion(&i2c_dev->completion); @@ -282,7 +311,6 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) { struct bcm2835_i2c_dev *i2c_dev; struct resource *mem, *irq; - u32 bus_clk_rate, divider; int ret; struct i2c_adapter *adap; @@ -306,27 +334,12 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) } ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", - &bus_clk_rate); + &i2c_dev->bus_clk_rate); if (ret < 0) { dev_warn(&pdev->dev, "Could not read clock-frequency property\n"); - bus_clk_rate = 100000; - } - - divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate); - /* - * Per the datasheet, the register is always interpreted as an even - * number, by rounding down. In other words, the LSB is ignored. So, - * if the LSB is set, increment the divider to avoid any issue. - */ - if (divider & 1) - divider++; - if ((divider < BCM2835_I2C_CDIV_MIN) || - (divider > BCM2835_I2C_CDIV_MAX)) { - dev_err(&pdev->dev, "Invalid clock-frequency\n"); - return -ENODEV; + i2c_dev->bus_clk_rate = 100000; } - bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); if (!irq) {