ARM: EXYNOS: Power domain DT support extension

Initial state of power domains might vary on different boards and with different bootloaders. This patch adds detection of initial state of power domains when being registered from DT.

Signed-off-by Tomasz Figa <[email protected]>

Signed-off-by Kyungmin Park <[email protected]>

---
 Documentation/devicetree/bindings/arm/exynos/power_domain.txt | 4 ----
 arch/arm/mach-exynos/pm_domains.c                             | 8 +++++---
 2 files changed, 5 insertions(+), 7 deletions(-)

Documentation/devicetree/bindings/arm/exynos/power_domain.txt +0 -4

index 6528e21..843b546 100644
@@ -9,10 +9,6 @@ Required Properties:
 - reg: physical base address of the controller and length of memory mapped
     region.
 
-Optional Properties:
-- samsung,exynos4210-pd-off: Specifies that the power domain is in turned-off
-    state during boot and remains to be turned-off until explicitly turned-on.
-
 Example:
 
        lcd0: power-domain-lcd0 {

arch/arm/mach-exynos/pm_domains.c +1 -2

index c0bc83a..d1abc1a 100644
@@ -89,6 +89,7 @@ static __init int exynos_pm_dt_parse_domains(void)
 
        for_each_compatible_node(np, NULL, "samsung,exynos4210-pd") {
                struct exynos_pm_domain *pd;
+               int on;
 
                pd = kzalloc(sizeof(*pd), GFP_KERNEL);
                if (!pd) {

@@ -97,14 +98,15 @@ static __init int exynos_pm_dt_parse_domains(void)
                        return -ENOMEM;
                }
 
-               if (of_get_property(np, "samsung,exynos4210-pd-off", NULL))
-                       pd->is_off = true;
                pd->name = np->name;
                pd->base = of_iomap(np, 0);
                pd->pd.power_off = exynos_pd_power_off;

This patch adds initialization of name field in generic power domain struct.

Signed-off-by Tomasz Figa <[email protected]>

Signed-off-by Kyungmin Park <[email protected]>

---
 arch/arm/mach-exynos/pm_domains.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

arch/arm/mach-exynos/pm_domains.c +0 -0

index d1abc1a..5b7ce7e 100644

arch/arm/mach-exynos/pm_domains.c +0 -1

                pd->base = of_iomap(np, 0);
                pd->pd.power_off = exynos_pd_power_off;
                pd->pd.power_on = exynos_pd_power_on;
--

1.7.12

arch/arm/mach-exynos/pm_domains.c static __init int exynos_pm_dt_parse_domains(void) · line 102

Quoted 3 lines

arch/arm/mach-exynos/pm_domains.c +2 -1

-               pd->name = np->name;
+               pd->pd.name = kstrdup(np->name, GFP_KERNEL);
+               pd->name = pd->pd.name;

Since device tree blob is always resident, why not just use np->name instead of copying it to a new place?

This patch adds a way to specify bindings between devices and power domains using device tree.

A device can be bound to particular power domain by adding a power-domain property containing a phandle to the domain. The device will be bound to the domain before binding a driver to it and unbound after unbinding a driver from it.

Signed-off-by Tomasz Figa <[email protected]>

Signed-off-by Kyungmin Park <[email protected]>

---
 .../bindings/arm/exynos/power_domain.txt           | 13 +++-
 arch/arm/mach-exynos/pm_domains.c                  | 82 ++++++++++++++++++++++
 2 files changed, 94 insertions(+), 1 deletion(-)

Documentation/devicetree/bindings/arm/exynos/power_domain.txt +4 -1

index 843b546..8ed914f 100644
@@ -4,14 +4,25 @@ Exynos processors include support for multiple power domains which are used
 to gate power to one or more peripherals on the processor.
 
 Required Properties:
-- compatiable: should be one of the following.
+- compatible: should be one of the following.
     * samsung,exynos4210-pd - for exynos4210 type power domain.
 - reg: physical base address of the controller and length of memory mapped
     region.
 
+Node of a device using power domains must have a power-domain property defined
+with a phandle to respective power domain.
+
 Example:
 
        lcd0: power-domain-lcd0 {
                compatible = "samsung,exynos4210-pd";

arch/arm/mach-exynos/pm_domains.c +39 -0

index 5b7ce7e..7b3b8a3 100644
@@ -19,6 +19,8 @@
 #include <linux/pm_domain.h>
 #include <linux/delay.h>
 #include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/sched.h>
 
 #include <mach/regs-pmu.h>
 #include <plat/devs.h>

@@ -83,14 +85,89 @@ static struct exynos_pm_domain PD = {                       \
 }
 
 #ifdef CONFIG_OF
+static void exynos_add_device_to_domain(struct exynos_pm_domain *pd,
+                                                       struct device *dev)
+{
+       int ret;
+
+       dev_dbg(dev, "adding to power domain %s\n", pd->pd.name);
+
+       while(1) {
+               ret = pm_genpd_add_device(&pd->pd, dev);
+               if (ret != -EAGAIN)
+                       break;
+               cond_resched();
+       }
+
+       pm_genpd_dev_need_restore(dev, true);
+}
+
+static void exynos_remove_device_from_domain(struct device *dev)
+{
+       struct generic_pm_domain *genpd = dev_to_genpd(dev);
+       int ret;
+
+       dev_dbg(dev, "removing from power domain %s\n", genpd->name);
+
+       while(1) {
+               ret = pm_genpd_remove_device(genpd, dev);
+               if (ret != -EAGAIN)
+                       break;
+               cond_resched();
+       }
+}
+
+static void exynos_read_domain_from_dt(struct device *dev)
+{
+       struct platform_device *pd_pdev;
+       struct exynos_pm_domain *pd;
+       struct device_node *node;

arch/arm/mach-exynos/pm_domains.c +14 -0

+
+static int exynos_pm_notifier_call(struct notifier_block *nb,
+                                   unsigned long event, void *data)
+{
+       struct device *dev = data;
+
+       switch (event) {
+       case BUS_NOTIFY_BIND_DRIVER:
+               if (dev->of_node)
+                       exynos_read_domain_from_dt(dev);
+
+               break;
+
+       case BUS_NOTIFY_UNBOUND_DRIVER:

arch/arm/mach-exynos/pm_domains.c +9 -1

+
 static __init int exynos_pm_dt_parse_domains(void)
 {
+       struct platform_device *pdev;
        struct device_node *np;
 
        for_each_compatible_node(np, NULL, "samsung,exynos4210-pd") {
                struct exynos_pm_domain *pd;
                int on;
 
+               pdev = of_find_device_by_node(np);
+
                pd = kzalloc(sizeof(*pd), GFP_KERNEL);
                if (!pd) {
                        pr_err("%s: failed to allocate memory for domain\n",

@@ -105,10 +182,15 @@ static __init int exynos_pm_dt_parse_domains(void)
                pd->pd.power_on = exynos_pd_power_on;
                pd->pd.of_node = np;
 
+               platform_set_drvdata(pdev, pd);
+
                on = __raw_readl(pd->base + 0x4) & S5P_INT_LOCAL_PWR_EN;
 
                pm_genpd_init(&pd->pd, NULL, !on);
        }
+
+       bus_register_notifier(&platform_bus_type, &platform_nb);
+
        return 0;
 }
 #else
--

1.7.12

Documentation/devicetree/bindings/arm/exynos/power_domain.txt Exynos processors include support for multiple power domains which are used · line 28

Quoted 7 lines

Documentation/devicetree/bindings/arm/exynos/power_domain.txt +7 -0

+Example of the node using power domain:
+
+       node {
+               /* ... */
+               power-domain = <&lcd0>;
+               /* ... */
+       };

Since the value of power-domain property is mostly samsung specific, should this be "samsung,power-domain" ?

Quoted 11 lines

arch/arm/mach-exynos/pm_domains.c +11 -0

+static void exynos_read_domain_from_dt(struct device *dev)
+{
+       struct platform_device *pd_pdev;
+       struct exynos_pm_domain *pd;
+       struct device_node *node;
+
+       node = of_parse_phandle(dev->of_node, "power-domain", 0);
+       if (!node)
+               return;
+       pd_pdev = of_find_device_by_node(node);
+       if (!pd_pdev)

arch/arm/mach-exynos/pm_domains.c static struct exynos_pm_domain PD = { \ · line 134

Quoted 4 lines

arch/arm/mach-exynos/pm_domains.c +4 -0

+               return;
+       pd = platform_get_drvdata(pd_pdev);
+       exynos_add_device_to_domain(pd, dev);
+}

The function "exynos_read_domain_from_dt" does more than reading the domain from dt. It associates a device with a power domain. So should it be renamed accordingly?

Quoted 20 lines

arch/arm/mach-exynos/pm_domains.c +20 -0

+
+static int exynos_pm_notifier_call(struct notifier_block *nb,
+                                   unsigned long event, void *data)
+{
+       struct device *dev = data;
+
+       switch (event) {
+       case BUS_NOTIFY_BIND_DRIVER:
+               if (dev->of_node)
+                       exynos_read_domain_from_dt(dev);
+
+               break;
+
+       case BUS_NOTIFY_UNBOUND_DRIVER:
+               exynos_remove_device_from_domain(dev);
+
+               break;
+       }
+       return NOTIFY_DONE;
+}

arch/arm/mach-exynos/pm_domains.c static struct exynos_pm_domain PD = { \ · line 158

Quoted 4 lines

arch/arm/mach-exynos/pm_domains.c +4 -0

+
+static struct notifier_block platform_nb = {
+       .notifier_call = exynos_pm_notifier_call,
+};

All the functions above are so generic (or can be made generic with minor modifications) that it can be placed outside of mach-exynos. Or better still, reusable for all platforms.

Quoted 3 lines

--
1.7.12

This patch looks so nice. I learned a thing or two from this patch.

Reviewed-by Thomas Abraham <[email protected]>

This patch series fixes two issues with existing DT support for Exynos power domains and extends it with the ability of binding devices to domains, basically making it possible to use power domains when using DT.

Tomasz Figa (3):
ARM: EXYNOS: pm_domain: Detect domain state on registration from DT
ARM: EXYNOS: pm_domain: Fix power domain name initialization
ARM: EXYNOS: pm_domain: Bind devices to power domains using DT

 .../bindings/arm/exynos/power_domain.txt           | 15 +++-
 arch/arm/mach-exynos/pm_domains.c                  | 93

+++++++++++++++++++++- 2 files changed, 100 insertions(+), 8 deletions(-)