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Subject[PATCH v7 2/2] mfd: syscon: Add hardware spinlock support
Date
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 <baolin.wang@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
---
Changes since v6:
- Treat hwlock id 0 as valid for regmap.

Changes since v5:
- Fix the case that hwspinlock is not enabled.

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 | 19 +++++++++++++++++++
2 files changed, 27 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..7eaa40b 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 +88,24 @@ 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 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) {
+ syscon_config.use_hwlock = true;
+ syscon_config.hwlock_id = ret;
+ syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
+ } else if (ret < 0) {
+ switch (ret) {
+ case -ENOENT:
+ /* Ignore missing hwlock, it's optional. */
+ break;
+ default:
+ pr_err("Failed to retrieve valid hwlock: %d\n", ret);
+ /* fall-through */
+ case -EPROBE_DEFER:
+ goto err_regmap;
+ }
+ }
+
syscon_config.reg_stride = reg_io_width;
syscon_config.val_bits = reg_io_width * 8;
syscon_config.max_register = resource_size(&res) - reg_io_width;
--
1.7.9.5
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