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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id d24-v6sm31199826pfe.40.2018.11.05.17.05.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 05 Nov 2018 17:05:09 -0800 (PST) Date: Mon, 5 Nov 2018 17:05:07 -0800 From: Bjorn Andersson To: Stephen Boyd Cc: Stephen Boyd , Michael Turquette , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, Taniya Das Subject: Re: [PATCH 2/2] clk: qcom: Support 'protected-clocks' property Message-ID: <20181106010507.GY2523@minitux> References: <20181105194011.43770-1-swboyd@chromium.org> <20181105194011.43770-3-swboyd@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181105194011.43770-3-swboyd@chromium.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 05 Nov 11:40 PST 2018, Stephen Boyd wrote: > Certain firmware configurations "protect" clks and cause the entire > system to reboot when a non-secure OS such as Linux tries to read or > write protected clk registers. But other firmware configurations allow > reading or writing the same registers, and they may actually require > that the OS use the otherwise locked down clks. Support the > 'protected-clocks' property by never registering these protected clks > with the common clk framework. This way, when firmware is protecting > these clks we won't have the chance to ever read or write these > registers and take down the entire system. > > Cc: Taniya Das > Cc: Bjorn Andersson > Signed-off-by: Stephen Boyd Reviewed-by: Bjorn Andersson Tested-by: Bjorn Andersson Regards, Bjorn > --- > drivers/clk/qcom/common.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c > index db9b2471ac40..0a48ed56833b 100644 > --- a/drivers/clk/qcom/common.c > +++ b/drivers/clk/qcom/common.c > @@ -191,6 +191,22 @@ int qcom_cc_register_sleep_clk(struct device *dev) > } > EXPORT_SYMBOL_GPL(qcom_cc_register_sleep_clk); > > +/* Drop 'protected-clocks' from the list of clocks to register */ > +static void qcom_cc_drop_protected(struct device *dev, struct qcom_cc *cc) > +{ > + struct device_node *np = dev->of_node; > + struct property *prop; > + const __be32 *p; > + u32 i; > + > + of_property_for_each_u32(np, "protected-clocks", prop, p, i) { > + if (i >= cc->num_rclks) > + continue; > + > + cc->rclks[i] = NULL; > + } > +} > + > static struct clk_hw *qcom_cc_clk_hw_get(struct of_phandle_args *clkspec, > void *data) > { > @@ -251,6 +267,8 @@ int qcom_cc_really_probe(struct platform_device *pdev, > cc->rclks = rclks; > cc->num_rclks = num_clks; > > + qcom_cc_drop_protected(dev, cc); > + > for (i = 0; i < num_clks; i++) { > if (!rclks[i]) > continue; > -- > Sent by a computer through tubes >