From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: [PATCH v7 4/5] clk: Provide critical clock support Date: Wed, 22 Jul 2015 14:04:14 +0100 Message-ID: <1437570255-21049-5-git-send-email-lee.jones@linaro.org> References: <1437570255-21049-1-git-send-email-lee.jones@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1437570255-21049-1-git-send-email-lee.jones@linaro.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: devicetree@vger.kernel.org, mturquette@linaro.org, kernel@stlinux.com, s.hauer@pengutronix.de, sboyd@codeaurora.org, geert@linux-m68k.org, maxime.ripard@free-electrons.com, Lee Jones List-Id: devicetree@vger.kernel.org Lots of platforms contain clocks which if turned off would prove fatal. The only way to recover from these catastrophic failures is to restart the board(s). Now, when a clock provider is registered with the framework it is possible for a list of critical clocks to be supplied which must be kept ungated. Each clock mentioned in the newly introduced 'critical-clock' property will be clk_prepare_enable()d where the normal references will be taken. This will prevent the common clk framework from attempting to gate them during the normal clk_disable_unused() and disable_clock() procedures. Note that it will still be possible for knowledgeable drivers to turn these clocks off using clk_{enable,disable}_critical() calls. Signed-off-by: Lee Jones --- drivers/clk/clk-conf.c | 45 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c index aad4796..f83c1c2 100644 --- a/drivers/clk/clk-conf.c +++ b/drivers/clk/clk-conf.c @@ -116,6 +116,45 @@ static int __set_clk_rates(struct device_node *node, bool clk_supplier) return 0; } +static int __set_critical_clocks(struct device_node *node, bool clk_supplier) +{ + struct of_phandle_args clkspec; + struct clk *clk; + struct property *prop; + const __be32 *cur; + uint32_t index; + int ret; + + if (!clk_supplier) + return 0; + + of_property_for_each_u32(node, "critical-clock", prop, cur, index) { + clkspec.np = node; + clkspec.args_count = 1; + clkspec.args[0] = index; + + clk = of_clk_get_from_provider(&clkspec); + if (IS_ERR(clk)) { + pr_err("clk: couldn't get clock %u for %s\n", + index, node->full_name); + return PTR_ERR(clk); + } + + clk_init_critical(clk); + + ret = clk_prepare_enable(clk); + if (ret) { + pr_err("Failed to enable clock %u for %s: %d\n", + index, node->full_name, ret); + return ret; + } + + pr_debug("Setting clock as critical %pC\n", clk); + } + + return 0; +} + /** * of_clk_set_defaults() - parse and set assigned clocks configuration * @node: device node to apply clock settings for @@ -139,6 +178,10 @@ int of_clk_set_defaults(struct device_node *node, bool clk_supplier) if (rc < 0) return rc; - return __set_clk_rates(node, clk_supplier); + rc = __set_clk_rates(node, clk_supplier); + if (rc < 0) + return rc; + + return __set_critical_clocks(node, clk_supplier); } EXPORT_SYMBOL_GPL(of_clk_set_defaults); -- 1.9.1