On 9 June 2016 at 20:09, Andy Gross [off-list ref] wrote:

On Thu, Jun 09, 2016 at 09:39:34AM +0200, Ulf Hansson wrote:

quoted

+ Daniel

On 19 May 2016 at 07:00, Andy Gross [off-list ref] wrote:

quoted

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 <redacted>
---
 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.

quoted

quoted

+               }
+
+               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.

I did a little research.

I think you should be able to use the struct cpuidle_ops->init()
callback. This is being invoked when the arm cpuidle driver is
initialized.

arm_idle_init()
  ->arm_cpuidle_init()
     ->cpuidle_ops->init()

In the QCOM case, it's the spm driver that registers these cpuidle_ops
(drivers/soc/qcom/spm.c). If you fold in the code from $subject patch
in qcom_cpuidle_init(), that should work I think.

Kind regards
Uffe