On 30 November 2017 at 18:38, Vladimir Zapolskiy
[off-list ref] wrote:

On 11/30/2017 11:10 AM, Baolin Wang wrote:

quoted

Some system control registers need hardware spinlock to synchronize
between the multiple subsystems, so we should add hardware spinlock
support for syscon.

Signed-off-by: Baolin Wang <redacted>
Acked-by: Rob Herring <robh@kernel.org>
---
Changes since v4:
 - Add one exapmle to show how to add hwlock.
 - Fix the coding style issue.

Changes since v3:
 - Add error handling for of_hwspin_lock_get_id()

Changes since v2:
 - Add acked tag from Rob.

Changes since v1:
 - Remove timeout configuration.
 - Modify the binding file to add hwlocks.
---
 Documentation/devicetree/bindings/mfd/syscon.txt |    8 ++++++++
 drivers/mfd/syscon.c                             |   21 +++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
index 8b92d45..25d9e9c 100644
--- a/Documentation/devicetree/bindings/mfd/syscon.txt
+++ b/Documentation/devicetree/bindings/mfd/syscon.txt

@@ -16,9 +16,17 @@ Required properties:
 Optional property:
 - reg-io-width: the size (in bytes) of the IO accesses that should be
   performed on the device.
+- hwlocks: reference to a phandle of a hardware spinlock provider node.

 Examples:
 gpr: iomuxc-gpr@20e0000 {
      compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
      reg = <0x020e0000 0x38>;
+     hwlocks = <&hwlock1 1>;
+};
+
+hwlock1: hwspinlock@40500000 {
+     ...
+     reg = <0x40500000 0x1000>;
+     #hwlock-cells = <1>;
 };

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index b93fe4c..5b67dbc 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c

@@ -13,6 +13,7 @@
  */

 #include <linux/err.h>
+#include <linux/hwspinlock.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/list.h>

@@ -87,6 +88,26 @@ static struct syscon *of_syscon_register(struct device_node *np)
      if (ret)
              reg_io_width = 4;

+     ret = of_hwspin_lock_get_id(np, 0);
+     if (ret > 0) {
+             syscon_config.hwlock_id = ret;
+             syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
+     } else {
+             switch (ret) {
+             case -ENOENT:
+                     /* Ignore missing hwlock, it's optional. */
+                     break;
+             case 0:
+                     ret = -EINVAL;
+                     /* fall-through */

It breaks the execution on all kernels without CONFIG_HWSPINLOCK enabled.

Ah, your are correct. Sorry, I missed this case. I will fix this in
next version. Thanks.

-- 
Baolin.wang
Best Regards