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 <[email protected]> > Cc: Bjorn Andersson <[email protected]> > Signed-off-by: Stephen Boyd <[email protected]>
Reviewed-by: Bjorn Andersson <[email protected]> Tested-by: Bjorn Andersson <[email protected]> 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 >
