[PATCH 1/5] soc: qcom: Add suspend to idle support

[Andy Gross]

On Thu, Jun 09, 2016 at 09:39:34AM +0200, Ulf Hansson wrote:
> + Daniel
> 
> On 19 May 2016 at 07:00, Andy Gross <andy.gross at linaro.org> wrote:
> > This patch adds suspend to idle support for Qualcomm processors.  While
> > suspend to memory will be a valid state, there won't be any special
> > handling or power savings over the suspend to idle.
> >
> > Signed-off-by: Andy Gross <andy.gross at linaro.org>
> > ---
> >  drivers/soc/qcom/Makefile  |  1 +
> >  drivers/soc/qcom/suspend.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 78 insertions(+)
> >  create mode 100644 drivers/soc/qcom/suspend.c
> >
> > diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> > index fdd664e..7c479d3 100644
> > --- a/drivers/soc/qcom/Makefile
> > +++ b/drivers/soc/qcom/Makefile
> > @@ -7,3 +7,4 @@ obj-$(CONFIG_QCOM_SMEM_STATE) += smem_state.o
> >  obj-$(CONFIG_QCOM_SMP2P)       += smp2p.o
> >  obj-$(CONFIG_QCOM_SMSM)        += smsm.o
> >  obj-$(CONFIG_QCOM_WCNSS_CTRL) += wcnss_ctrl.o
> > +obj-$(CONFIG_SUSPEND)  +=      suspend.o
> > diff --git a/drivers/soc/qcom/suspend.c b/drivers/soc/qcom/suspend.c
> > new file mode 100644
> > index 0000000..7d3f2dd
> > --- /dev/null
> > +++ b/drivers/soc/qcom/suspend.c
> > @@ -0,0 +1,77 @@
> > +/*
> > + * (C) Copyright 2016 Linaro Ltd.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > + * as published by the Free Software Foundation; version 2
> > + * of the License.
> > + */
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/cpuidle.h>
> > +#include <linux/suspend.h>
> > +
> > +
> > +static void qcom_pm_enter_freeze(struct cpuidle_device *dev,
> > +       struct cpuidle_driver *drv,
> > +       int index)
> > +{
> > +       drv->states[index].enter(dev, drv, index);
> > +}
> > +
> > +static const struct of_device_id qcom_idle_state_match[] = {
> > +       { .compatible = "qcom,idle-state-spc", },
> > +       { },
> > +};
> > +
> > +static const struct platform_suspend_ops qcom_suspend_ops = {
> > +       .valid          = suspend_valid_only_mem,
> > +};
> > +
> > +static int __init qcom_pm_init(void)
> > +{
> > +       struct cpuidle_device *cpu_dev;
> > +       struct cpuidle_driver *cpu_drv;
> > +       int state_count;
> > +       struct device_node *state_np, *cpu_np;
> > +       const struct of_device_id *match;
> > +       int i;
> > +
> > +       /* configure CPU enter_freeze if applicable */
> > +       for_each_present_cpu(i) {
> > +               cpu_np = of_get_cpu_node(i, NULL);
> > +               cpu_dev = per_cpu_ptr(cpuidle_devices, i);
> > +               cpu_drv = cpuidle_get_cpu_driver(cpu_dev);
> > +
> > +               if (!cpu_dev || !cpu_drv) {
> > +                       of_node_put(cpu_np);
> > +                       return -EPROBE_DEFER;
> 
> This isn't a driver, so returning -EPROBE_DEFER doesn't make sense.

Right.  It's not like it'll get retried.

> > +               }
> > +
> > +               state_count = 0;
> > +               state_np = of_parse_phandle(cpu_np, "cpu-idle-states",
> > +                                                 state_count);
> > +
> > +               while (state_np) {
> > +                       match = of_match_node(qcom_idle_state_match,
> > +                                             state_np);
> > +
> > +                       state_count++;
> > +                       if (match)
> > +                               cpu_drv->states[state_count].enter_freeze =
> > +                                               &qcom_pm_enter_freeze;
> > +                       of_node_put(state_np);
> > +
> > +                       state_np = of_parse_phandle(cpu_np, "cpu-idle-states",
> > +                                                   state_count);
> > +               }
> > +
> > +               of_node_put(cpu_np);
> > +       }
> > +
> > +       suspend_set_ops(&qcom_suspend_ops);
> 
> I don't think this will work!
> 
> When building a multi defconfig for ARM, you might overwrite the
> suspend_ops (there's only one set) as here you don't know that it's
> actually the QCOM platform that is running, right!?
> 
> Perhaps this code actually belongs closer to the cpuidle driver?

Hmmmm, I might have to get creative.  I originally had a DT entry for the pm,
but that doesn't make sense as this is purely a software construct.  The db410c
uses the arm cpuidle driver so I can't really hook it in there.  I'll have to
come up with something else.


Andy