The current implementation does not allow two different devices to use
a common hwspinlock. This patch set proposes to have, as an option, some
hwspinlocks shared between several users.
Below is an example that explain the need for this:
exti: interrupt-controller@5000d000 {
compatible = "st,stm32mp1-exti", "syscon";
interrupt-controller;
#interrupt-cells = <2>;
reg = <0x5000d000 0x400>;
hwlocks = <&hsem 1>;
};
The two drivers (stm32mp1-exti and syscon) refer to the same hwlock.
With the current hwspinlock implementation, only the first driver succeeds
in requesting (hwspin_lock_request_specific) the hwlock. The second request
fails.
The proposed approach does not modify the API, but extends the DT 'hwlocks'
property with a second optional parameter (the first one identifies an
hwlock) that specifies whether an hwlock is requested for exclusive usage
(current behavior) or can be shared between several users.
Examples:
hwlocks = <&hsem 8>; Ref to hwlock #8 for exclusive usage
hwlocks = <&hsem 8 0>; Ref to hwlock #8 for exclusive (0) usage
hwlocks = <&hsem 8 1>; Ref to hwlock #8 for shared (1) usage
As a constraint, the #hwlock-cells value must be 1 or 2.
In the current implementation, this can have theorically any value but:
- all of the exisiting drivers use the same value : 1.
- the framework supports only one value : 1 (see implementation of
of_hwspin_lock_simple_xlate())
Hence, it shall not be a problem to restrict this value to 1 or 2 since
it won't break any driver.
Changes since v1:
* Removed useless 'status = "okay"' from stm32mp157c.dtsi
Fabien Dessenne (6):
dt-bindings: hwlock: add support of shared locks
hwspinlock: allow sharing of hwspinlocks
dt-bindings: hwlock: update STM32 #hwlock-cells value
ARM: dts: stm32: Add hwspinlock node for stm32mp157 SoC
ARM: dts: stm32: Add hwlock for irqchip on stm32mp157
ARM: dts: stm32: hwlocks for GPIO for stm32mp157
.../devicetree/bindings/hwlock/hwlock.txt | 27 +++++--
.../bindings/hwlock/st,stm32-hwspinlock.txt | 6 +-
Documentation/hwspinlock.txt | 10 ++-
arch/arm/boot/dts/stm32mp157-pinctrl.dtsi | 2 +
arch/arm/boot/dts/stm32mp157c.dtsi | 9 +++
drivers/hwspinlock/hwspinlock_core.c | 82 +++++++++++++++++-----
drivers/hwspinlock/hwspinlock_internal.h | 2 +
7 files changed, 107 insertions(+), 31 deletions(-)
--
2.7.4
Declare a shared hwlock to be used by all gpio / pin controllers.
Signed-off-by: Fabien Dessenne <[email protected]>
---
arch/arm/boot/dts/stm32mp157-pinctrl.dtsi | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/boot/dts/stm32mp157-pinctrl.dtsi b/arch/arm/boot/dts/stm32mp157-pinctrl.dtsi
index 6b3a9c6..9fd562a 100644
--- a/arch/arm/boot/dts/stm32mp157-pinctrl.dtsi
+++ b/arch/arm/boot/dts/stm32mp157-pinctrl.dtsi
@@ -14,6 +14,7 @@
ranges = <0 0x50002000 0xa400>;
interrupt-parent = <&exti>;
st,syscfg = <&exti 0x60 0xff>;
+ hwlocks = <&hsem 0 1>;
pins-are-numbered;
gpioa: gpio@50002000 {
@@ -424,6 +425,7 @@
pins-are-numbered;
interrupt-parent = <&exti>;
st,syscfg = <&exti 0x60 0xff>;
+ hwlocks = <&hsem 0 1>;
gpioz: gpio@54004000 {
gpio-controller;
--
2.7.4
Use a value of 2, so users can share hwlocks.
Signed-off-by: Fabien Dessenne <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
---
Documentation/devicetree/bindings/hwlock/st,stm32-hwspinlock.txt | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/hwlock/st,stm32-hwspinlock.txt b/Documentation/devicetree/bindings/hwlock/st,stm32-hwspinlock.txt
index adf4f000..60a3716 100644
--- a/Documentation/devicetree/bindings/hwlock/st,stm32-hwspinlock.txt
+++ b/Documentation/devicetree/bindings/hwlock/st,stm32-hwspinlock.txt
@@ -4,8 +4,8 @@ STM32 Hardware Spinlock Device Binding
Required properties :
- compatible : should be "st,stm32-hwspinlock".
- reg : the register address of hwspinlock.
-- #hwlock-cells : hwlock users only use the hwlock id to represent a specific
- hwlock, so the number of cells should be <1> here.
+- #hwlock-cells : should be <2> so the hwlock users use the hwlock id to
+ represent a specific hwlock and define its shared / exclusive attribute.
- clock-names : Must contain "hsem".
- clocks : Must contain a phandle entry for the clock in clock-names, see the
common clock bindings.
@@ -16,7 +16,7 @@ Please look at the generic hwlock binding for usage information for consumers,
Example of hwlock provider:
hwspinlock@4c000000 {
compatible = "st,stm32-hwspinlock";
- #hwlock-cells = <1>;
+ #hwlock-cells = <2>;
reg = <0x4c000000 0x400>;
clocks = <&rcc HSEM>;
clock-names = "hsem";
--
2.7.4
The current implementation does not allow different devices to use a
common hwspinlock. Offer the possibility to use the same hwspinlock by
several users.
If a device registers to the framework with #hwlock-cells = 2, then
the second parameter of the 'hwlocks' DeviceTree property defines
whether an hwlock is requested for an exclusive or a shared usage.
If a device registers with #hwlock-cells = 1, then all the hwlocks are
for an exclusive usage.
Signed-off-by: Fabien Dessenne <[email protected]>
---
Documentation/hwspinlock.txt | 10 ++--
drivers/hwspinlock/hwspinlock_core.c | 82 +++++++++++++++++++++++++-------
drivers/hwspinlock/hwspinlock_internal.h | 2 +
3 files changed, 73 insertions(+), 21 deletions(-)
diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
index ed640a2..e6ce2dd 100644
--- a/Documentation/hwspinlock.txt
+++ b/Documentation/hwspinlock.txt
@@ -54,9 +54,11 @@ Should be called from a process context (might sleep).
struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
Assign a specific hwspinlock id and return its address, or NULL
-if that hwspinlock is already in use. Usually board code will
-be calling this function in order to reserve specific hwspinlock
-ids for predefined purposes.
+if that hwspinlock is already in use and not shared. If that specific
+hwspinlock is declared as shared, it can be requested and used by
+several users.
+Usually board code will be calling this function in order to reserve
+specific hwspinlock ids for predefined purposes.
Should be called from a process context (might sleep).
@@ -368,11 +370,13 @@ of which represents a single hardware lock::
* struct hwspinlock - this struct represents a single hwspinlock instance
* @bank: the hwspinlock_device structure which owns this lock
* @lock: initialized and used by hwspinlock core
+ * @refcount: number of users (when shared)
* @priv: private data, owned by the underlying platform-specific hwspinlock drv
*/
struct hwspinlock {
struct hwspinlock_device *bank;
spinlock_t lock;
+ unsigned int refcount;
void *priv;
};
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 2bad40d..53afdeb 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -25,6 +25,8 @@
/* radix tree tags */
#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */
+#define HWSPINLOCK_EXCLUSIVE (1) /* tags an hwspinlock as exclusive */
+#define HWSPINLOCK_SHARED (2) /* tags an hwspinlock as shared */
/*
* A radix tree is used to maintain the available hwspinlock instances.
@@ -291,7 +293,7 @@ EXPORT_SYMBOL_GPL(__hwspin_unlock);
* @hwlock_spec: hwlock specifier as found in the device tree
*
* This is a simple translation function, suitable for hwspinlock platform
- * drivers that only has a lock specifier length of 1.
+ * drivers that only has a lock specifier length of 1 or 2.
*
* Returns a relative index of the lock within a specified bank on success,
* or -EINVAL on invalid specifier cell count.
@@ -299,7 +301,8 @@ EXPORT_SYMBOL_GPL(__hwspin_unlock);
static inline int
of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec)
{
- if (WARN_ON(hwlock_spec->args_count != 1))
+ if (WARN_ON(hwlock_spec->args_count != 1 &&
+ hwlock_spec->args_count != 2))
return -EINVAL;
return hwlock_spec->args[0];
@@ -322,11 +325,12 @@ of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec)
int of_hwspin_lock_get_id(struct device_node *np, int index)
{
struct of_phandle_args args;
- struct hwspinlock *hwlock;
+ struct hwspinlock *hwlock, *tmp;
struct radix_tree_iter iter;
void **slot;
int id;
int ret;
+ unsigned int tag;
ret = of_parse_phandle_with_args(np, "hwlocks", "#hwlock-cells", index,
&args);
@@ -361,6 +365,37 @@ int of_hwspin_lock_get_id(struct device_node *np, int index)
}
id += hwlock->bank->base_id;
+ /* Set the EXCLUSIVE / SHARED tag */
+ if (args.args_count == 2 && args.args[1]) {
+ /* Tag SHARED unless already tagged EXCLUSIVE */
+ if (radix_tree_tag_get(&hwspinlock_tree, id,
+ HWSPINLOCK_EXCLUSIVE)) {
+ ret = -EINVAL;
+ goto out;
+ }
+ tag = HWSPINLOCK_SHARED;
+ } else {
+ /* Tag EXCLUSIVE unless already tagged SHARED */
+ if (radix_tree_tag_get(&hwspinlock_tree, id,
+ HWSPINLOCK_SHARED)) {
+ ret = -EINVAL;
+ goto out;
+ }
+ tag = HWSPINLOCK_EXCLUSIVE;
+ }
+
+ /* mark this hwspinlock */
+ hwlock = radix_tree_lookup(&hwspinlock_tree, id);
+ if (!hwlock) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ tmp = radix_tree_tag_set(&hwspinlock_tree, id, tag);
+
+ /* self-sanity check which should never fail */
+ WARN_ON(tmp != hwlock);
+
out:
of_node_put(args.np);
return ret ? ret : id;
@@ -483,6 +518,7 @@ int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
spin_lock_init(&hwlock->lock);
hwlock->bank = bank;
+ hwlock->refcount = 0;
ret = hwspin_lock_register_single(hwlock, base_id + i);
if (ret)
@@ -625,7 +661,7 @@ static int __hwspin_lock_request(struct hwspinlock *hwlock)
{
struct device *dev = hwlock->bank->dev;
struct hwspinlock *tmp;
- int ret;
+ int ret, id;
/* prevent underlying implementation from being removed */
if (!try_module_get(dev->driver->owner)) {
@@ -642,13 +678,18 @@ static int __hwspin_lock_request(struct hwspinlock *hwlock)
return ret;
}
+ /* update shareable refcount */
+ id = hwlock_to_id(hwlock);
+ if (radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_SHARED) &&
+ hwlock->refcount++)
+ goto out;
+
/* mark hwspinlock as used, should not fail */
- tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
- HWSPINLOCK_UNUSED);
+ tmp = radix_tree_tag_clear(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
/* self-sanity check that should never fail */
WARN_ON(tmp != hwlock);
-
+out:
return ret;
}
@@ -742,9 +783,9 @@ struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
/* sanity check (this shouldn't happen) */
WARN_ON(hwlock_to_id(hwlock) != id);
- /* make sure this hwspinlock is unused */
- ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
- if (ret == 0) {
+ /* make sure this hwspinlock is unused or shareable */
+ if (!radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_SHARED) &&
+ !radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED)) {
pr_warn("hwspinlock %u is already in use\n", id);
hwlock = NULL;
goto out;
@@ -777,7 +818,7 @@ int hwspin_lock_free(struct hwspinlock *hwlock)
{
struct device *dev;
struct hwspinlock *tmp;
- int ret;
+ int ret, id;
if (!hwlock) {
pr_err("invalid hwlock\n");
@@ -788,30 +829,35 @@ int hwspin_lock_free(struct hwspinlock *hwlock)
mutex_lock(&hwspinlock_tree_lock);
/* make sure the hwspinlock is used */
- ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock),
- HWSPINLOCK_UNUSED);
+ id = hwlock_to_id(hwlock);
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
if (ret == 1) {
dev_err(dev, "%s: hwlock is already free\n", __func__);
dump_stack();
ret = -EINVAL;
- goto out;
+ goto unlock;
}
/* notify the underlying device that power is not needed */
ret = pm_runtime_put(dev);
if (ret < 0)
- goto out;
+ goto unlock;
+
+ /* update shareable refcount */
+ if (radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_SHARED) &&
+ --hwlock->refcount)
+ goto put;
/* mark this hwspinlock as available */
- tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock),
- HWSPINLOCK_UNUSED);
+ tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
/* sanity check (this shouldn't happen) */
WARN_ON(tmp != hwlock);
+put:
module_put(dev->driver->owner);
-out:
+unlock:
mutex_unlock(&hwspinlock_tree_lock);
return ret;
}
diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h
index 9eb6bd0..c808e11 100644
--- a/drivers/hwspinlock/hwspinlock_internal.h
+++ b/drivers/hwspinlock/hwspinlock_internal.h
@@ -35,11 +35,13 @@ struct hwspinlock_ops {
* struct hwspinlock - this struct represents a single hwspinlock instance
* @bank: the hwspinlock_device structure which owns this lock
* @lock: initialized and used by hwspinlock core
+ * @refcount: number of users (when shared)
* @priv: private data, owned by the underlying platform-specific hwspinlock drv
*/
struct hwspinlock {
struct hwspinlock_device *bank;
spinlock_t lock;
+ unsigned int refcount;
void *priv;
};
--
2.7.4
Define a hwspinlock to be used by the irq controller driver and the
syscon driver.
Signed-off-by: Fabien Dessenne <[email protected]>
---
arch/arm/boot/dts/stm32mp157c.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm/boot/dts/stm32mp157c.dtsi b/arch/arm/boot/dts/stm32mp157c.dtsi
index 824d7e1..417bdf7 100644
--- a/arch/arm/boot/dts/stm32mp157c.dtsi
+++ b/arch/arm/boot/dts/stm32mp157c.dtsi
@@ -921,6 +921,7 @@
interrupt-controller;
#interrupt-cells = <2>;
reg = <0x5000d000 0x400>;
+ hwlocks = <&hsem 1 1>;
};
syscfg: syscon@50020000 {
--
2.7.4
Use #hwlock-cells value to define whether the locks can be shared
by several users.
Signed-off-by: Fabien Dessenne <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
---
.../devicetree/bindings/hwlock/hwlock.txt | 27 ++++++++++++++++------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt
index 085d1f5..e98088a 100644
--- a/Documentation/devicetree/bindings/hwlock/hwlock.txt
+++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt
@@ -13,7 +13,7 @@ hwlock providers:
Required properties:
- #hwlock-cells: Specifies the number of cells needed to represent a
- specific lock.
+ specific lock. Shall be 1 or 2 (see hwlocks below).
hwlock users:
=============
@@ -27,6 +27,11 @@ Required properties:
#hwlock-cells. The list can have just a single hwlock
or multiple hwlocks, with each hwlock represented by
a phandle and a corresponding args specifier.
+ If #hwlock-cells is 1, all of the locks are exclusive
+ (cannot be used by several users).
+ If #hwlock-cells is 2, the value of the second cell
+ defines whether the lock is for exclusive usage (0) or
+ shared (1) i.e. can be used by several users.
Optional properties:
- hwlock-names: List of hwlock name strings defined in the same order
@@ -46,14 +51,22 @@ of length 1.
...
};
-2. Example of a node using multiple specific hwlocks:
+2. Example of nodes using multiple and shared specific hwlocks:
-The following example has a node requesting two hwlocks, a hwlock within
-the hwlock device node 'hwlock1' with #hwlock-cells value of 1, and another
-hwlock within the hwlock device node 'hwlock2' with #hwlock-cells value of 2.
+The following example has a nodeA requesting two hwlocks:
+- an exclusive one (#hwlock-cells = 1) within the hwlock device node 'hwlock1'
+- a shared one (#hwlock-cells = 2, second cell = 1) within the hwlock device
+ node 'hwlock2'.
+The shared lock is also be used by nodeB.
- node {
+ nodeA {
...
- hwlocks = <&hwlock1 2>, <&hwlock2 0 3>;
+ hwlocks = <&hwlock1 2>, <&hwlock2 0 1>;
...
};
+
+ nodeB {
+ ...
+ hwlocks = <&hwlock2 0 1>;
+ ...
+ };
\ No newline at end of file
--
2.7.4
Declare hwspinlock device for stm32mp157 SoC
Signed-off-by: Fabien Dessenne <[email protected]>
---
arch/arm/boot/dts/stm32mp157c.dtsi | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/arm/boot/dts/stm32mp157c.dtsi b/arch/arm/boot/dts/stm32mp157c.dtsi
index 105e21f..824d7e1 100644
--- a/arch/arm/boot/dts/stm32mp157c.dtsi
+++ b/arch/arm/boot/dts/stm32mp157c.dtsi
@@ -886,6 +886,14 @@
status = "disabled";
};
+ hsem: hwspinlock@4c000000 {
+ compatible = "st,stm32-hwspinlock";
+ #hwlock-cells = <2>;
+ reg = <0x4c000000 0x400>;
+ clocks = <&rcc HSEM>;
+ clock-names = "hsem";
+ };
+
ipcc: mailbox@4c001000 {
compatible = "st,stm32mp1-ipcc";
#mbox-cells = <1>;
--
2.7.4
Hi
I Got Rob's Reviewed-by. Any further comments?
Fabien
On 25/04/2019 11:17 AM, Fabien Dessenne wrote:
> The current implementation does not allow two different devices to use
> a common hwspinlock. This patch set proposes to have, as an option, some
> hwspinlocks shared between several users.
>
> Below is an example that explain the need for this:
> exti: interrupt-controller@5000d000 {
> compatible = "st,stm32mp1-exti", "syscon";
> interrupt-controller;
> #interrupt-cells = <2>;
> reg = <0x5000d000 0x400>;
> hwlocks = <&hsem 1>;
> };
> The two drivers (stm32mp1-exti and syscon) refer to the same hwlock.
> With the current hwspinlock implementation, only the first driver succeeds
> in requesting (hwspin_lock_request_specific) the hwlock. The second request
> fails.
>
>
> The proposed approach does not modify the API, but extends the DT 'hwlocks'
> property with a second optional parameter (the first one identifies an
> hwlock) that specifies whether an hwlock is requested for exclusive usage
> (current behavior) or can be shared between several users.
> Examples:
> hwlocks = <&hsem 8>; Ref to hwlock #8 for exclusive usage
> hwlocks = <&hsem 8 0>; Ref to hwlock #8 for exclusive (0) usage
> hwlocks = <&hsem 8 1>; Ref to hwlock #8 for shared (1) usage
>
> As a constraint, the #hwlock-cells value must be 1 or 2.
> In the current implementation, this can have theorically any value but:
> - all of the exisiting drivers use the same value : 1.
> - the framework supports only one value : 1 (see implementation of
> of_hwspin_lock_simple_xlate())
> Hence, it shall not be a problem to restrict this value to 1 or 2 since
> it won't break any driver.
>
> Changes since v1:
> * Removed useless 'status = "okay"' from stm32mp157c.dtsi
>
> Fabien Dessenne (6):
> dt-bindings: hwlock: add support of shared locks
> hwspinlock: allow sharing of hwspinlocks
> dt-bindings: hwlock: update STM32 #hwlock-cells value
> ARM: dts: stm32: Add hwspinlock node for stm32mp157 SoC
> ARM: dts: stm32: Add hwlock for irqchip on stm32mp157
> ARM: dts: stm32: hwlocks for GPIO for stm32mp157
>
> .../devicetree/bindings/hwlock/hwlock.txt | 27 +++++--
> .../bindings/hwlock/st,stm32-hwspinlock.txt | 6 +-
> Documentation/hwspinlock.txt | 10 ++-
> arch/arm/boot/dts/stm32mp157-pinctrl.dtsi | 2 +
> arch/arm/boot/dts/stm32mp157c.dtsi | 9 +++
> drivers/hwspinlock/hwspinlock_core.c | 82 +++++++++++++++++-----
> drivers/hwspinlock/hwspinlock_internal.h | 2 +
> 7 files changed, 107 insertions(+), 31 deletions(-)
>