Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965163AbbGVNTq (ORCPT ); Wed, 22 Jul 2015 09:19:46 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:35276 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756761AbbGVNEZ (ORCPT ); Wed, 22 Jul 2015 09:04:25 -0400 From: Lee Jones To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: kernel@stlinux.com, mturquette@linaro.org, sboyd@codeaurora.org, devicetree@vger.kernel.org, geert@linux-m68k.org, maxime.ripard@free-electrons.com, s.hauer@pengutronix.de, Lee Jones Subject: [PATCH v7 3/5] clk: Supply the critical clock {init, enable, disable} framework Date: Wed, 22 Jul 2015 14:04:13 +0100 Message-Id: <1437570255-21049-4-git-send-email-lee.jones@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437570255-21049-1-git-send-email-lee.jones@linaro.org> References: <1437570255-21049-1-git-send-email-lee.jones@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5229 Lines: 172 These new API calls will firstly provide a mechanisms to tag a clock as critical and secondly allow any knowledgeable driver to (un)gate clocks, even if they are marked as critical. Suggested-by: Maxime Ripard Signed-off-by: Lee Jones --- drivers/clk/clk.c | 45 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/clk-provider.h | 2 ++ include/linux/clk.h | 30 +++++++++++++++++++++++++++++ 3 files changed, 77 insertions(+) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 61c3fc5..486b1da 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -46,6 +46,21 @@ static struct clk_core *clk_core_lookup(const char *name); /*** private data structures ***/ +/** + * struct critical - Provides 'play' over critical clocks. A clock can be + * marked as critical, meaning that it should not be + * disabled. However, if a driver which is aware of the + * critical behaviour wants to control it, it can do so + * using clk_enable_critical() and clk_disable_critical(). + * + * @enabled Is clock critical? Once set, doesn't change + * @leave_on Self explanatory. Can be disabled by knowledgeable drivers + */ +struct critical { + bool enabled; + bool leave_on; +}; + struct clk_core { const char *name; const struct clk_ops *ops; @@ -75,6 +90,7 @@ struct clk_core { struct dentry *dentry; #endif struct kref ref; + struct critical critical; }; struct clk { @@ -995,6 +1011,10 @@ static void clk_core_disable(struct clk_core *clk) if (WARN_ON(clk->enable_count == 0)) return; + /* Refuse to turn off a critical clock */ + if (clk->enable_count == 1 && clk->critical.leave_on) + return; + if (--clk->enable_count > 0) return; @@ -1037,6 +1057,13 @@ void clk_disable(struct clk *clk) } EXPORT_SYMBOL_GPL(clk_disable); +void clk_disable_critical(struct clk *clk) +{ + clk->core->critical.leave_on = false; + clk_disable(clk); +} +EXPORT_SYMBOL_GPL(clk_disable_critical); + static int clk_core_enable(struct clk_core *clk) { int ret = 0; @@ -1100,6 +1127,15 @@ int clk_enable(struct clk *clk) } EXPORT_SYMBOL_GPL(clk_enable); +int clk_enable_critical(struct clk *clk) +{ + if (clk->core->critical.enabled) + clk->core->critical.leave_on = true; + + return clk_enable(clk); +} +EXPORT_SYMBOL_GPL(clk_enable_critical); + static unsigned long clk_core_round_rate_nolock(struct clk_core *clk, unsigned long rate, unsigned long min_rate, @@ -2482,6 +2518,15 @@ fail_out: } EXPORT_SYMBOL_GPL(clk_register); +void clk_init_critical(struct clk *clk) +{ + struct critical *critical = &clk->core->critical; + + critical->enabled = true; + critical->leave_on = true; +} +EXPORT_SYMBOL_GPL(clk_init_critical); + /* * Free memory allocated for a clock. * Caller must hold prepare_lock. diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 5591ea7..15ef8c9 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -563,6 +563,8 @@ struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw); void clk_unregister(struct clk *clk); void devm_clk_unregister(struct device *dev, struct clk *clk); +void clk_init_critical(struct clk *clk); + /* helper functions */ const char *__clk_get_name(struct clk *clk); struct clk_hw *__clk_get_hw(struct clk *clk); diff --git a/include/linux/clk.h b/include/linux/clk.h index 8381bbf..9807f3b 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -231,6 +231,19 @@ struct clk *devm_clk_get(struct device *dev, const char *id); int clk_enable(struct clk *clk); /** + * clk_enable_critical - inform the system when the clock source should be + * running, even if clock is critical. + * @clk: clock source + * + * If the clock can not be enabled/disabled, this should return success. + * + * May be called from atomic contexts. + * + * Returns success (0) or negative errno. + */ +int clk_enable_critical(struct clk *clk); + +/** * clk_disable - inform the system when the clock source is no longer required. * @clk: clock source * @@ -247,6 +260,23 @@ int clk_enable(struct clk *clk); void clk_disable(struct clk *clk); /** + * clk_disable_critical - inform the system when the clock source is no + * longer required, even if clock is critical. + * @clk: clock source + * + * Inform the system that a clock source is no longer required by + * a driver and may be shut down. + * + * May be called from atomic contexts. + * + * Implementation detail: if the clock source is shared between + * multiple drivers, clk_enable_critical() calls must be balanced + * by the same number of clk_disable_critical() calls for the clock + * source to be disabled. + */ +void clk_disable_critical(struct clk *clk); + +/** * clk_get_rate - obtain the current clock rate (in Hz) for a clock source. * This is only valid once the clock source has been enabled. * @clk: clock source -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/