From patchwork Thu Sep 15 07:24:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: AngeloGioacchino Del Regno X-Patchwork-Id: 12976953 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 66786ECAAD3 for ; Thu, 15 Sep 2022 07:28:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4TvvTdSW5V8xkABHheUXwmxjnENauPzD879IezHv/VA=; b=rHPdw3yItcU/xt iuAHGBwzaVIMG2nnTWhKlFovb/sXHZeBw5K0NDhi111bwRtzAWCJYQEsGWqWJapnBepeLebMEGLRg FDeFbwnK7sSbj8xvreStIvWO3IDjrWlB2zxFOqTRutXSiGPYZpL2404/yL2RvNfc219T/iHTAsToh SR+n/jLB9/+YiC2HWCW/Z5A6hlCQItY9RVAJZpsPBnClouuKqcmvpeHZn3ikXJIfH8kCPgxRd0RkN r1SDUn2p3Nqi+B8A9poDpbuL773oRh/LiaMt4ogkAoGbi8hbEbYllSHmk6dBcXaUklGHK9xDVF+96 Htn9Er3qOVVVALcw7pcw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oYjH4-002kTv-5Y; Thu, 15 Sep 2022 07:27:02 +0000 Received: from madras.collabora.co.uk ([46.235.227.172]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oYjFH-002j6C-QD; Thu, 15 Sep 2022 07:25:14 +0000 Received: from IcarusMOD.eternityproject.eu (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madras.collabora.co.uk (Postfix) with ESMTPSA id 9C6B66601FC5; Thu, 15 Sep 2022 08:25:08 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1663226709; bh=5taqdJni3v9MTETZZQrSrsVMS+J9z4yESK9uElqm7Ss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X79806TcrrWh+bCR1DrvTXCe2aulBbEchnG7U9SGDD4EcvLgTZbcSF1n8Bi6NOS7b RsiImcsqIfbK/XZrsn1zeUc7dM0XUZFKptSzrF2Rr8OtWUqzsoiUubZzX2VFthS3PP 3X9A8tLSYNwfcdauE3uY4XDlEenr7L+RmQJPgU4vB6RJtyc3xrl99HEbD7/YdrzxbF v4ap9kAw0vPxQ0E4ztQN5nadBY7Kdr9pqZox1pn/zMB8nZFZLuhzU1DOr0sy3vcIpl Lvhov2R+cFaF7GlQseTTBV0v1V6cU0LumRhvNzsqXKKrf3DeI9/MVar7z5LSkWld4K shTxq+1SBm0BQ== From: AngeloGioacchino Del Regno To: matthias.bgg@gmail.com Cc: mturquette@baylibre.com, sboyd@kernel.org, angelogioacchino.delregno@collabora.com, wenst@chromium.org, miles.chen@mediatek.com, rex-bc.chen@mediatek.com, nfraprado@collabora.com, chun-jie.chen@mediatek.com, jose.exposito89@gmail.com, drinkcat@chromium.org, weiyi.lu@mediatek.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org Subject: [PATCH v2 03/10] clk: mediatek: mux: add clk notifier functions Date: Thu, 15 Sep 2022 09:24:51 +0200 Message-Id: <20220915072458.18232-4-angelogioacchino.delregno@collabora.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220915072458.18232-1-angelogioacchino.delregno@collabora.com> References: <20220915072458.18232-1-angelogioacchino.delregno@collabora.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220915_002512_198412_5604E13B X-CRM114-Status: GOOD ( 19.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Chen-Yu Tsai With device frequency scaling, the mux clock that (indirectly) feeds the device selects between a dedicated PLL, and some other stable clocks. When a clk rate change is requested, the (normally) upstream PLL is reconfigured. It's possible for the clock output of the PLL to become unstable during this process. To avoid causing the device to glitch, the mux should temporarily be switched over to another "stable" clock during the PLL rate change. This is done with clk notifiers. This patch adds common functions for notifiers to temporarily and transparently reparent mux clocks. This was loosely based on commit 8adfb08605a9 ("clk: sunxi-ng: mux: Add clk notifier functions"). Signed-off-by: Chen-Yu Tsai [Angelo: Changed mtk_mux_nb to hold a pointer to clk_ops instead of mtk_mux] Co-Developed-by: AngeloGioacchino Del Regno Signed-off-by: AngeloGioacchino Del Regno Reviewed-by: Miles Chen --- drivers/clk/mediatek/clk-mux.c | 38 ++++++++++++++++++++++++++++++++++ drivers/clk/mediatek/clk-mux.h | 15 ++++++++++++++ 2 files changed, 53 insertions(+) diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c index cd5f9fd8cb98..4421e4859257 100644 --- a/drivers/clk/mediatek/clk-mux.c +++ b/drivers/clk/mediatek/clk-mux.c @@ -4,6 +4,7 @@ * Author: Owen Chen */ +#include #include #include #include @@ -259,4 +260,41 @@ void mtk_clk_unregister_muxes(const struct mtk_mux *muxes, int num, } EXPORT_SYMBOL_GPL(mtk_clk_unregister_muxes); +/* + * This clock notifier is called when the frequency of the parent + * PLL clock is to be changed. The idea is to switch the parent to a + * stable clock, such as the main oscillator, while the PLL frequency + * stabilizes. + */ +static int mtk_clk_mux_notifier_cb(struct notifier_block *nb, + unsigned long event, void *_data) +{ + struct clk_notifier_data *data = _data; + struct clk_hw *hw = __clk_get_hw(data->clk); + struct mtk_mux_nb *mux_nb = to_mtk_mux_nb(nb); + int ret = 0; + + switch (event) { + case PRE_RATE_CHANGE: + mux_nb->original_index = mux_nb->ops->get_parent(hw); + ret = mux_nb->ops->set_parent(hw, mux_nb->bypass_index); + break; + case POST_RATE_CHANGE: + case ABORT_RATE_CHANGE: + ret = mux_nb->ops->set_parent(hw, mux_nb->original_index); + break; + } + + return notifier_from_errno(ret); +} + +int devm_mtk_clk_mux_notifier_register(struct device *dev, struct clk *clk, + struct mtk_mux_nb *mux_nb) +{ + mux_nb->nb.notifier_call = mtk_clk_mux_notifier_cb; + + return devm_clk_notifier_register(dev, clk, &mux_nb->nb); +} +EXPORT_SYMBOL_GPL(devm_mtk_clk_mux_notifier_register); + MODULE_LICENSE("GPL"); diff --git a/drivers/clk/mediatek/clk-mux.h b/drivers/clk/mediatek/clk-mux.h index 6539c58f5d7d..83ff420f4ebe 100644 --- a/drivers/clk/mediatek/clk-mux.h +++ b/drivers/clk/mediatek/clk-mux.h @@ -7,12 +7,14 @@ #ifndef __DRV_CLK_MTK_MUX_H #define __DRV_CLK_MTK_MUX_H +#include #include #include struct clk; struct clk_hw_onecell_data; struct clk_ops; +struct device; struct device_node; struct mtk_mux { @@ -89,4 +91,17 @@ int mtk_clk_register_muxes(const struct mtk_mux *muxes, void mtk_clk_unregister_muxes(const struct mtk_mux *muxes, int num, struct clk_hw_onecell_data *clk_data); +struct mtk_mux_nb { + struct notifier_block nb; + const struct clk_ops *ops; + + u8 bypass_index; /* Which parent to temporarily use */ + u8 original_index; /* Set by notifier callback */ +}; + +#define to_mtk_mux_nb(_nb) container_of(_nb, struct mtk_mux_nb, nb) + +int devm_mtk_clk_mux_notifier_register(struct device *dev, struct clk *clk, + struct mtk_mux_nb *mux_nb); + #endif /* __DRV_CLK_MTK_MUX_H */